Add packet capture to debug bundle and CLI

client/Dockerfile

@@ -17,6 +17,7 @@ ENV \
     NETBIRD_BIN="/usr/local/bin/netbird" \
     NB_LOG_FILE="console,/var/log/netbird/client.log" \
     NB_DAEMON_ADDR="unix:///var/run/netbird.sock" \
+    NB_ENABLE_CAPTURE="false" \
     NB_ENTRYPOINT_SERVICE_TIMEOUT="30"
 
 ENTRYPOINT [ "/usr/local/bin/netbird-entrypoint.sh" ]

client/Dockerfile-rootless

@@ -23,6 +23,7 @@ ENV \
     NB_DAEMON_ADDR="unix:///var/lib/netbird/netbird.sock" \
     NB_LOG_FILE="console,/var/lib/netbird/client.log" \
     NB_DISABLE_DNS="true" \
+    NB_ENABLE_CAPTURE="false" \
     NB_ENTRYPOINT_SERVICE_TIMEOUT="30"
 
 ENTRYPOINT [ "/usr/local/bin/netbird-entrypoint.sh" ]

client/cmd/capture.go

@@ -0,0 +1,186 @@
+package cmd
+
+import (
+	"context"
+	"fmt"
+	"io"
+	"os"
+	"os/signal"
+	"path/filepath"
+	"strings"
+	"syscall"
+
+	"github.com/spf13/cobra"
+	"google.golang.org/grpc/status"
+	"google.golang.org/protobuf/types/known/durationpb"
+
+	"github.com/netbirdio/netbird/client/proto"
+	"github.com/netbirdio/netbird/util/capture"
+)
+
+var captureCmd = &cobra.Command{
+	Use:   "capture",
+	Short: "Capture packets on the WireGuard interface",
+	Long: `Captures decrypted packets flowing through the WireGuard interface.
+
+Default output is human-readable text. Use --pcap or --output for pcap binary.
+Requires --enable-capture to be set at service install or reconfigure time.
+
+Examples:
+  netbird debug capture
+  netbird debug capture host 100.64.0.1 and port 443
+  netbird debug capture tcp
+  netbird debug capture icmp
+  netbird debug capture src host 10.0.0.1 and dst port 80
+  netbird debug capture -o capture.pcap
+  netbird debug capture --pcap | tshark -r -
+  netbird debug capture --pcap | tcpdump -r - -n`,
+	Args: cobra.ArbitraryArgs,
+	RunE: runCapture,
+}
+
+func init() {
+	debugCmd.AddCommand(captureCmd)
+
+	captureCmd.Flags().Bool("pcap", false, "Force pcap binary output (default when --output is set)")
+	captureCmd.Flags().BoolP("verbose", "v", false, "Show seq/ack, TTL, window, total length")
+	captureCmd.Flags().Bool("ascii", false, "Print payload as ASCII after each packet (useful for HTTP)")
+	captureCmd.Flags().Uint32("snap-len", 0, "Max bytes per packet (0 = full)")
+	captureCmd.Flags().DurationP("duration", "d", 0, "Capture duration (0 = until interrupted)")
+	captureCmd.Flags().StringP("output", "o", "", "Write pcap to file instead of stdout")
+}
+
+func runCapture(cmd *cobra.Command, args []string) error {
+	conn, err := getClient(cmd)
+	if err != nil {
+		return err
+	}
+	defer func() {
+		if err := conn.Close(); err != nil {
+			cmd.PrintErrf(errCloseConnection, err)
+		}
+	}()
+
+	client := proto.NewDaemonServiceClient(conn)
+
+	req, err := buildCaptureRequest(cmd, args)
+	if err != nil {
+		return err
+	}
+
+	ctx, cancel := signal.NotifyContext(cmd.Context(), syscall.SIGINT, syscall.SIGTERM)
+	defer cancel()
+
+	stream, err := client.StartCapture(ctx, req)
+	if err != nil {
+		return handleCaptureError(err)
+	}
+
+	// First Recv is the empty acceptance message from the server. If the
+	// device is unavailable (kernel WG, not connected, capture disabled),
+	// the server returns an error instead.
+	if _, err := stream.Recv(); err != nil {
+		return handleCaptureError(err)
+	}
+
+	out, cleanup, err := captureOutput(cmd)
+	if err != nil {
+		return err
+	}
+	defer cleanup()
+
+	if req.TextOutput {
+		cmd.PrintErrf("Capturing packets... Press Ctrl+C to stop.\n")
+	} else {
+		cmd.PrintErrf("Capturing packets (pcap)... Press Ctrl+C to stop.\n")
+	}
+
+	return streamCapture(ctx, cmd, stream, out)
+}
+
+func buildCaptureRequest(cmd *cobra.Command, args []string) (*proto.StartCaptureRequest, error) {
+	req := &proto.StartCaptureRequest{}
+
+	if len(args) > 0 {
+		expr := strings.Join(args, " ")
+		if _, err := capture.ParseFilter(expr); err != nil {
+			return nil, fmt.Errorf("invalid filter: %w", err)
+		}
+		req.FilterExpr = expr
+	}
+
+	if snap, _ := cmd.Flags().GetUint32("snap-len"); snap > 0 {
+		req.SnapLen = snap
+	}
+	if d, _ := cmd.Flags().GetDuration("duration"); d != 0 {
+		if d < 0 {
+			return nil, fmt.Errorf("duration must not be negative")
+		}
+		req.Duration = durationpb.New(d)
+	}
+	req.Verbose, _ = cmd.Flags().GetBool("verbose")
+	req.Ascii, _ = cmd.Flags().GetBool("ascii")
+
+	outPath, _ := cmd.Flags().GetString("output")
+	forcePcap, _ := cmd.Flags().GetBool("pcap")
+	req.TextOutput = !forcePcap && outPath == ""
+
+	return req, nil
+}
+
+func streamCapture(ctx context.Context, cmd *cobra.Command, stream proto.DaemonService_StartCaptureClient, out io.Writer) error {
+	for {
+		pkt, err := stream.Recv()
+		if err != nil {
+			if ctx.Err() != nil {
+				cmd.PrintErrf("\nCapture stopped.\n")
+				return nil //nolint:nilerr // user interrupted
+			}
+			if err == io.EOF {
+				cmd.PrintErrf("\nCapture finished.\n")
+				return nil
+			}
+			return handleCaptureError(err)
+		}
+		if _, err := out.Write(pkt.GetData()); err != nil {
+			return fmt.Errorf("write output: %w", err)
+		}
+	}
+}
+
+// captureOutput returns the writer for capture data and a cleanup function.
+func captureOutput(cmd *cobra.Command) (io.Writer, func(), error) {
+	outPath, _ := cmd.Flags().GetString("output")
+	if outPath == "" {
+		return os.Stdout, func() {
+			// no cleanup needed for stdout
+		}, nil
+	}
+
+	f, err := os.CreateTemp(filepath.Dir(outPath), filepath.Base(outPath)+".*.tmp")
+	if err != nil {
+		return nil, nil, fmt.Errorf("create output file: %w", err)
+	}
+	tmpPath := f.Name()
+	return f, func() {
+		if err := f.Close(); err != nil {
+			cmd.PrintErrf("close output file: %v\n", err)
+		}
+		if fi, err := os.Stat(tmpPath); err == nil && fi.Size() > 0 {
+			if err := os.Rename(tmpPath, outPath); err != nil {
+				cmd.PrintErrf("rename output file: %v\n", err)
+			} else {
+				cmd.PrintErrf("Wrote %s\n", outPath)
+			}
+		} else {
+			os.Remove(tmpPath)
+		}
+	}, nil
+}
+
+func handleCaptureError(err error) error {
+	if s, ok := status.FromError(err); ok {
+		return fmt.Errorf("%s", s.Message())
+	}
+	return err
+}

client/cmd/debug.go

@@ -9,6 +9,7 @@ import (
 	log "github.com/sirupsen/logrus"
 	"github.com/spf13/cobra"
 	"google.golang.org/grpc/status"
+	"google.golang.org/protobuf/types/known/durationpb"
 
 	"github.com/netbirdio/netbird/client/internal"
 	"github.com/netbirdio/netbird/client/internal/debug"
@@ -239,11 +240,50 @@ func runForDuration(cmd *cobra.Command, args []string) error {
 		}()
 	}
 
+	captureStarted := false
+	if wantCapture, _ := cmd.Flags().GetBool("capture"); wantCapture {
+		captureTimeout := duration + 30*time.Second
+		const maxBundleCapture = 10 * time.Minute
+		if captureTimeout > maxBundleCapture {
+			captureTimeout = maxBundleCapture
+		}
+		_, err := client.StartBundleCapture(cmd.Context(), &proto.StartBundleCaptureRequest{
+			Timeout: durationpb.New(captureTimeout),
+		})
+		if err != nil {
+			cmd.PrintErrf("Failed to start packet capture: %v\n", status.Convert(err).Message())
+		} else {
+			captureStarted = true
+			cmd.Println("Packet capture started.")
+			// Safety: always stop on exit, even if the normal stop below runs too.
+			defer func() {
+				if captureStarted {
+					stopCtx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
+					defer cancel()
+					if _, err := client.StopBundleCapture(stopCtx, &proto.StopBundleCaptureRequest{}); err != nil {
+						cmd.PrintErrf("Failed to stop packet capture: %v\n", err)
+					}
+				}
+			}()
+		}
+	}
+
 	if waitErr := waitForDurationOrCancel(cmd.Context(), duration, cmd); waitErr != nil {
 		return waitErr
 	}
 	cmd.Println("\nDuration completed")
 
+	if captureStarted {
+		stopCtx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
+		defer cancel()
+		if _, err := client.StopBundleCapture(stopCtx, &proto.StopBundleCaptureRequest{}); err != nil {
+			cmd.PrintErrf("Failed to stop packet capture: %v\n", err)
+		} else {
+			captureStarted = false
+			cmd.Println("Packet capture stopped.")
+		}
+	}
+
 	if cpuProfilingStarted {
 		if _, err := client.StopCPUProfile(cmd.Context(), &proto.StopCPUProfileRequest{}); err != nil {
 			cmd.PrintErrf("Failed to stop CPU profiling: %v\n", err)
@@ -416,4 +456,5 @@ func init() {
 	forCmd.Flags().BoolVarP(&systemInfoFlag, "system-info", "S", true, "Adds system information to the debug bundle")
 	forCmd.Flags().BoolVarP(&uploadBundleFlag, "upload-bundle", "U", false, "Uploads the debug bundle to a server")
 	forCmd.Flags().StringVar(&uploadBundleURLFlag, "upload-bundle-url", types.DefaultBundleURL, "Service URL to get an URL to upload the debug bundle")
+	forCmd.Flags().Bool("capture", false, "Capture packets during the debug duration and include in bundle")
 }

client/cmd/root.go

@@ -75,6 +75,7 @@ var (
 	mtu                     uint16
 	profilesDisabled        bool
 	updateSettingsDisabled  bool
+	captureEnabled          bool
 
 	rootCmd = &cobra.Command{
 		Use:          "netbird",

client/cmd/service.go

@@ -44,6 +44,7 @@ func init() {
 	serviceCmd.AddCommand(runCmd, startCmd, stopCmd, restartCmd, svcStatusCmd, installCmd, uninstallCmd, reconfigureCmd, resetParamsCmd)
 	serviceCmd.PersistentFlags().BoolVar(&profilesDisabled, "disable-profiles", false, "Disables profiles feature. If enabled, the client will not be able to change or edit any profile. To persist this setting, use: netbird service install --disable-profiles")
 	serviceCmd.PersistentFlags().BoolVar(&updateSettingsDisabled, "disable-update-settings", false, "Disables update settings feature. If enabled, the client will not be able to change or edit any settings. To persist this setting, use: netbird service install --disable-update-settings")
+	serviceCmd.PersistentFlags().BoolVar(&captureEnabled, "enable-capture", false, "Enables packet capture via 'netbird debug capture'. To persist, use: netbird service install --enable-capture")
 
 	rootCmd.PersistentFlags().StringVarP(&serviceName, "service", "s", defaultServiceName, "Netbird system service name")
 	serviceEnvDesc := `Sets extra environment variables for the service. ` +

client/cmd/service_controller.go

@@ -61,7 +61,7 @@ func (p *program) Start(svc service.Service) error {
 			}
 		}
 
-		serverInstance := server.New(p.ctx, util.FindFirstLogPath(logFiles), configPath, profilesDisabled, updateSettingsDisabled)
+		serverInstance := server.New(p.ctx, util.FindFirstLogPath(logFiles), configPath, profilesDisabled, updateSettingsDisabled, captureEnabled)
 		if err := serverInstance.Start(); err != nil {
 			log.Fatalf("failed to start daemon: %v", err)
 		}

client/cmd/service_installer.go

@@ -59,6 +59,10 @@ func buildServiceArguments() []string {
 		args = append(args, "--disable-update-settings")
 	}
 
+	if captureEnabled {
+		args = append(args, "--enable-capture")
+	}
+
 	return args
 }
 

client/cmd/service_params.go

@@ -28,6 +28,7 @@ type serviceParams struct {
 	LogFiles              []string          `json:"log_files,omitempty"`
 	DisableProfiles       bool              `json:"disable_profiles,omitempty"`
 	DisableUpdateSettings bool              `json:"disable_update_settings,omitempty"`
+	EnableCapture         bool              `json:"enable_capture,omitempty"`
 	ServiceEnvVars        map[string]string `json:"service_env_vars,omitempty"`
 }
 
@@ -78,6 +79,7 @@ func currentServiceParams() *serviceParams {
 		LogFiles:              logFiles,
 		DisableProfiles:       profilesDisabled,
 		DisableUpdateSettings: updateSettingsDisabled,
+		EnableCapture:         captureEnabled,
 	}
 
 	if len(serviceEnvVars) > 0 {
@@ -142,6 +144,10 @@ func applyServiceParams(cmd *cobra.Command, params *serviceParams) {
 		updateSettingsDisabled = params.DisableUpdateSettings
 	}
 
+	if !serviceCmd.PersistentFlags().Changed("enable-capture") {
+		captureEnabled = params.EnableCapture
+	}
+
 	applyServiceEnvParams(cmd, params)
 }
 

client/cmd/service_params_test.go

@@ -500,6 +500,7 @@ func fieldToGlobalVar(field string) string {
 		"LogFiles":              "logFiles",
 		"DisableProfiles":       "profilesDisabled",
 		"DisableUpdateSettings": "updateSettingsDisabled",
+		"EnableCapture":         "captureEnabled",
 		"ServiceEnvVars":        "serviceEnvVars",
 	}
 	if v, ok := m[field]; ok {

client/cmd/testutil_test.go

@@ -152,7 +152,7 @@ func startClientDaemon(
 	s := grpc.NewServer()
 
 	server := client.New(ctx,
-		"", "", false, false)
+		"", "", false, false, false)
 	if err := server.Start(); err != nil {
 		t.Fatal(err)
 	}

client/embed/embed.go

@@ -24,6 +24,7 @@ import (
 	"github.com/netbirdio/netbird/client/system"
 	"github.com/netbirdio/netbird/shared/management/domain"
 	mgmProto "github.com/netbirdio/netbird/shared/management/proto"
+	"github.com/netbirdio/netbird/util/capture"
 )
 
 var (
@@ -489,6 +490,22 @@ func (c *Client) getEngine() (*internal.Engine, error) {
 	return engine, nil
 }
 
+// SetCapture sets or clears packet capture on this client's WireGuard device.
+// Pass nil to disable capture.
+func (c *Client) SetCapture(sess *capture.Session) error {
+	engine, err := c.getEngine()
+	if err != nil {
+		return err
+	}
+	// Explicit nil check to avoid wrapping a nil *Session in the
+	// device.PacketCapture interface, which would appear non-nil to
+	// FilteredDevice and cause a nil-pointer dereference in Offer.
+	if sess == nil {
+		return engine.SetCapture(nil)
+	}
+	return engine.SetCapture(sess)
+}
+
 func (c *Client) getNet() (*wgnetstack.Net, netip.Addr, error) {
 	engine, err := c.getEngine()
 	if err != nil {

client/firewall/uspfilter/filter.go

@@ -115,12 +115,13 @@ type Manager struct {
 
 	localipmanager *localIPManager
 
-	udpTracker  *conntrack.UDPTracker
+	udpTracker     *conntrack.UDPTracker
-	icmpTracker *conntrack.ICMPTracker
+	icmpTracker    *conntrack.ICMPTracker
-	tcpTracker  *conntrack.TCPTracker
+	tcpTracker     *conntrack.TCPTracker
-	forwarder   atomic.Pointer[forwarder.Forwarder]
+	forwarder      atomic.Pointer[forwarder.Forwarder]
-	logger      *nblog.Logger
+	pendingCapture atomic.Pointer[forwarder.PacketCapture]
-	flowLogger  nftypes.FlowLogger
+	logger         *nblog.Logger
+	flowLogger     nftypes.FlowLogger
 
 	blockRule firewall.Rule
 
@@ -351,6 +352,19 @@ func (m *Manager) determineRouting() error {
 	return nil
 }
 
+// SetPacketCapture sets or clears packet capture on the forwarder endpoint.
+// This captures outbound response packets that bypass the FilteredDevice in netstack mode.
+func (m *Manager) SetPacketCapture(pc forwarder.PacketCapture) {
+	if pc == nil {
+		m.pendingCapture.Store(nil)
+	} else {
+		m.pendingCapture.Store(&pc)
+	}
+	if fwder := m.forwarder.Load(); fwder != nil {
+		fwder.SetCapture(pc)
+	}
+}
+
 // initForwarder initializes the forwarder, it disables routing on errors
 func (m *Manager) initForwarder() error {
 	if m.forwarder.Load() != nil {
@@ -370,6 +384,10 @@ func (m *Manager) initForwarder() error {
 		return fmt.Errorf("create forwarder: %w", err)
 	}
 
+	if pc := m.pendingCapture.Load(); pc != nil {
+		forwarder.SetCapture(*pc)
+	}
+
 	m.forwarder.Store(forwarder)
 
 	log.Debug("forwarder initialized")
@@ -614,6 +632,7 @@ func (m *Manager) resetState() {
 	}
 
 	if fwder := m.forwarder.Load(); fwder != nil {
+		fwder.SetCapture(nil)
 		fwder.Stop()
 	}
 

client/firewall/uspfilter/forwarder/endpoint.go

@@ -12,12 +12,19 @@ import (
 	nblog "github.com/netbirdio/netbird/client/firewall/uspfilter/log"
 )
 
+// PacketCapture captures raw packets for debugging. Implementations must be
+// safe for concurrent use and must not block.
+type PacketCapture interface {
+	Offer(data []byte, outbound bool)
+}
+
 // endpoint implements stack.LinkEndpoint and handles integration with the wireguard device
 type endpoint struct {
 	logger     *nblog.Logger
 	dispatcher stack.NetworkDispatcher
 	device     *wgdevice.Device
 	mtu        atomic.Uint32
+	capture    atomic.Pointer[PacketCapture]
 }
 
 func (e *endpoint) Attach(dispatcher stack.NetworkDispatcher) {
@@ -54,13 +61,17 @@ func (e *endpoint) WritePackets(pkts stack.PacketBufferList) (int, tcpip.Error)
 			continue
 		}
 
-		// Send the packet through WireGuard
+		pktBytes := data.AsSlice()
+
 		address := netHeader.DestinationAddress()
-		err := e.device.CreateOutboundPacket(data.AsSlice(), address.AsSlice())
+		if err := e.device.CreateOutboundPacket(pktBytes, address.AsSlice()); err != nil {
-		if err != nil {
 			e.logger.Error1("CreateOutboundPacket: %v", err)
 			continue
 		}
+
+		if pc := e.capture.Load(); pc != nil {
+			(*pc).Offer(pktBytes, true)
+		}
 		written++
 	}
 

client/firewall/uspfilter/forwarder/forwarder.go

@@ -139,6 +139,16 @@ func New(iface common.IFaceMapper, logger *nblog.Logger, flowLogger nftypes.Flow
 	return f, nil
 }
 
+// SetCapture sets or clears the packet capture on the forwarder endpoint.
+// This captures outbound packets that bypass the FilteredDevice (netstack forwarding).
+func (f *Forwarder) SetCapture(pc PacketCapture) {
+	if pc == nil {
+		f.endpoint.capture.Store(nil)
+		return
+	}
+	f.endpoint.capture.Store(&pc)
+}
+
 func (f *Forwarder) InjectIncomingPacket(payload []byte) error {
 	if len(payload) < header.IPv4MinimumSize {
 		return fmt.Errorf("packet too small: %d bytes", len(payload))

client/firewall/uspfilter/forwarder/icmp.go

@@ -270,5 +270,9 @@ func (f *Forwarder) injectICMPReply(id stack.TransportEndpointID, icmpPayload []
 		return 0
 	}
 
+	if pc := f.endpoint.capture.Load(); pc != nil {
+		(*pc).Offer(fullPacket, true)
+	}
+
 	return len(fullPacket)
 }

client/iface/device/device_filter.go

@@ -3,6 +3,7 @@ package device
 import (
 	"net/netip"
 	"sync"
+	"sync/atomic"
 
 	"golang.zx2c4.com/wireguard/tun"
 )
@@ -28,11 +29,20 @@ type PacketFilter interface {
 	SetTCPPacketHook(ip netip.Addr, dPort uint16, hook func(packet []byte) bool)
 }
 
+// PacketCapture captures raw packets for debugging. Implementations must be
+// safe for concurrent use and must not block.
+type PacketCapture interface {
+	// Offer submits a packet for capture. outbound is true for packets
+	// leaving the host (Read path), false for packets arriving (Write path).
+	Offer(data []byte, outbound bool)
+}
+
 // FilteredDevice to override Read or Write of packets
 type FilteredDevice struct {
 	tun.Device
 
 	filter    PacketFilter
+	capture   atomic.Pointer[PacketCapture]
 	mutex     sync.RWMutex
 	closeOnce sync.Once
 }
@@ -63,20 +73,25 @@ func (d *FilteredDevice) Read(bufs [][]byte, sizes []int, offset int) (n int, er
 	if n, err = d.Device.Read(bufs, sizes, offset); err != nil {
 		return 0, err
 	}
+
 	d.mutex.RLock()
 	filter := d.filter
 	d.mutex.RUnlock()
 
-	if filter == nil {
+	if filter != nil {
-		return
+		for i := 0; i < n; i++ {
+			if filter.FilterOutbound(bufs[i][offset:offset+sizes[i]], sizes[i]) {
+				bufs = append(bufs[:i], bufs[i+1:]...)
+				sizes = append(sizes[:i], sizes[i+1:]...)
+				n--
+				i--
+			}
+		}
 	}
 
-	for i := 0; i < n; i++ {
+	if pc := d.capture.Load(); pc != nil {
-		if filter.FilterOutbound(bufs[i][offset:offset+sizes[i]], sizes[i]) {
+		for i := 0; i < n; i++ {
-			bufs = append(bufs[:i], bufs[i+1:]...)
+			(*pc).Offer(bufs[i][offset:offset+sizes[i]], true)
-			sizes = append(sizes[:i], sizes[i+1:]...)
-			n--
-			i--
 		}
 	}
 
@@ -85,6 +100,13 @@ func (d *FilteredDevice) Read(bufs [][]byte, sizes []int, offset int) (n int, er
 
 // Write wraps write method with filtering feature
 func (d *FilteredDevice) Write(bufs [][]byte, offset int) (int, error) {
+	// Capture before filtering so dropped packets are still visible in captures.
+	if pc := d.capture.Load(); pc != nil {
+		for _, buf := range bufs {
+			(*pc).Offer(buf[offset:], false)
+		}
+	}
+
 	d.mutex.RLock()
 	filter := d.filter
 	d.mutex.RUnlock()
@@ -96,9 +118,10 @@ func (d *FilteredDevice) Write(bufs [][]byte, offset int) (int, error) {
 	filteredBufs := make([][]byte, 0, len(bufs))
 	dropped := 0
 	for _, buf := range bufs {
-		if !filter.FilterInbound(buf[offset:], len(buf)) {
+		if filter.FilterInbound(buf[offset:], len(buf)) {
-			filteredBufs = append(filteredBufs, buf)
 			dropped++
+		} else {
+			filteredBufs = append(filteredBufs, buf)
 		}
 	}
 
@@ -113,3 +136,14 @@ func (d *FilteredDevice) SetFilter(filter PacketFilter) {
 	d.filter = filter
 	d.mutex.Unlock()
 }
+
+// SetCapture sets or clears the packet capture sink. Pass nil to disable.
+// Uses atomic store so the hot path (Read/Write) is a single pointer load
+// with no locking overhead when capture is off.
+func (d *FilteredDevice) SetCapture(pc PacketCapture) {
+	if pc == nil {
+		d.capture.Store(nil)
+		return
+	}
+	d.capture.Store(&pc)
+}

client/iface/device/device_filter_test.go

@@ -158,7 +158,7 @@ func TestDeviceWrapperRead(t *testing.T) {
 			t.Errorf("unexpected error: %v", err)
 			return
 		}
-		if n != 0 {
+		if n != 1 {
 			t.Errorf("expected n=1, got %d", n)
 			return
 		}

client/internal/debug/debug.go

@@ -63,6 +63,7 @@ allocs.prof: Allocations profiling information.
 threadcreate.prof: Thread creation profiling information.
 cpu.prof: CPU profiling information.
 stack_trace.txt: Complete stack traces of all goroutines at the time of bundle creation.
+capture.pcap: Packet capture in pcap format. Only present when capture was running during bundle collection. Omitted from anonymized bundles because it contains raw decrypted packet data.
 
 
 Anonymization Process
@@ -235,6 +236,7 @@ type BundleGenerator struct {
 	syncResponse   *mgmProto.SyncResponse
 	logPath        string
 	cpuProfile     []byte
+	capturePath    string
 	refreshStatus  func() // Optional callback to refresh status before bundle generation
 	clientMetrics  MetricsExporter
 
@@ -257,7 +259,8 @@ type GeneratorDependencies struct {
 	SyncResponse   *mgmProto.SyncResponse
 	LogPath        string
 	CPUProfile     []byte
-	RefreshStatus  func() // Optional callback to refresh status before bundle generation
+	CapturePath    string
+	RefreshStatus  func()
 	ClientMetrics  MetricsExporter
 }
 
@@ -276,6 +279,7 @@ func NewBundleGenerator(deps GeneratorDependencies, cfg BundleConfig) *BundleGen
 		syncResponse:   deps.SyncResponse,
 		logPath:        deps.LogPath,
 		cpuProfile:     deps.CPUProfile,
+		capturePath:    deps.CapturePath,
 		refreshStatus:  deps.RefreshStatus,
 		clientMetrics:  deps.ClientMetrics,
 
@@ -345,6 +349,10 @@ func (g *BundleGenerator) createArchive() error {
 		log.Errorf("failed to add CPU profile to debug bundle: %v", err)
 	}
 
+	if err := g.addCaptureFile(); err != nil {
+		log.Errorf("failed to add capture file to debug bundle: %v", err)
+	}
+
 	if err := g.addStackTrace(); err != nil {
 		log.Errorf("failed to add stack trace to debug bundle: %v", err)
 	}
@@ -675,6 +683,29 @@ func (g *BundleGenerator) addCPUProfile() error {
 	return nil
 }
 
+func (g *BundleGenerator) addCaptureFile() error {
+	if g.capturePath == "" {
+		return nil
+	}
+
+	if g.anonymize {
+		log.Info("skipping capture file in anonymized bundle (contains raw packet data)")
+		return nil
+	}
+
+	f, err := os.Open(g.capturePath)
+	if err != nil {
+		return fmt.Errorf("open capture file: %w", err)
+	}
+	defer f.Close()
+
+	if err := g.addFileToZip(f, "capture.pcap"); err != nil {
+		return fmt.Errorf("add capture file to zip: %w", err)
+	}
+
+	return nil
+}
+
 func (g *BundleGenerator) addStackTrace() error {
 	buf := make([]byte, 5242880) // 5 MB buffer
 	n := runtime.Stack(buf, true)

client/internal/engine.go

@@ -27,6 +27,7 @@ import (
 	nberrors "github.com/netbirdio/netbird/client/errors"
 	"github.com/netbirdio/netbird/client/firewall"
 	firewallManager "github.com/netbirdio/netbird/client/firewall/manager"
+	"github.com/netbirdio/netbird/client/firewall/uspfilter/forwarder"
 	"github.com/netbirdio/netbird/client/iface"
 	"github.com/netbirdio/netbird/client/iface/device"
 	nbnetstack "github.com/netbirdio/netbird/client/iface/netstack"
@@ -67,6 +68,7 @@ import (
 	signal "github.com/netbirdio/netbird/shared/signal/client"
 	sProto "github.com/netbirdio/netbird/shared/signal/proto"
 	"github.com/netbirdio/netbird/util"
+	"github.com/netbirdio/netbird/util/capture"
 )
 
 // PeerConnectionTimeoutMax is a timeout of an initial connection attempt to a remote peer.
@@ -216,6 +218,8 @@ type Engine struct {
 	portForwardManager *portforward.Manager
 	srWatcher          *guard.SRWatcher
 
+	afpacketCapture *capture.AFPacketCapture
+
 	// Sync response persistence (protected by syncRespMux)
 	syncRespMux         sync.RWMutex
 	persistSyncResponse bool
@@ -1693,6 +1697,11 @@ func (e *Engine) parseNATExternalIPMappings() []string {
 }
 
 func (e *Engine) close() {
+	if e.afpacketCapture != nil {
+		e.afpacketCapture.Stop()
+		e.afpacketCapture = nil
+	}
+
 	log.Debugf("removing Netbird interface %s", e.config.WgIfaceName)
 
 	if e.wgInterface != nil {
@@ -2158,6 +2167,62 @@ func (e *Engine) Address() (netip.Addr, error) {
 	return e.wgInterface.Address().IP, nil
 }
 
+// SetCapture sets or clears packet capture on the WireGuard device.
+// On userspace WireGuard, it taps the FilteredDevice directly.
+// On kernel WireGuard (Linux), it falls back to AF_PACKET raw socket capture.
+// Pass nil to disable capture.
+func (e *Engine) SetCapture(pc device.PacketCapture) error {
+	e.syncMsgMux.Lock()
+	defer e.syncMsgMux.Unlock()
+
+	intf := e.wgInterface
+	if intf == nil {
+		return errors.New("wireguard interface not initialized")
+	}
+
+	if e.afpacketCapture != nil {
+		e.afpacketCapture.Stop()
+		e.afpacketCapture = nil
+	}
+
+	dev := intf.GetDevice()
+	if dev != nil {
+		dev.SetCapture(pc)
+		e.setForwarderCapture(pc)
+		return nil
+	}
+
+	// Kernel mode: no FilteredDevice. Use AF_PACKET on Linux.
+	if pc == nil {
+		return nil
+	}
+	sess, ok := pc.(*capture.Session)
+	if !ok {
+		return errors.New("filtered device not available and AF_PACKET requires *capture.Session")
+	}
+
+	afc := capture.NewAFPacketCapture(intf.Name(), sess)
+	if err := afc.Start(); err != nil {
+		return fmt.Errorf("start AF_PACKET capture on %s: %w", intf.Name(), err)
+	}
+	e.afpacketCapture = afc
+	return nil
+}
+
+// setForwarderCapture propagates capture to the USP filter's forwarder endpoint.
+// This captures outbound response packets that bypass the FilteredDevice in netstack mode.
+func (e *Engine) setForwarderCapture(pc device.PacketCapture) {
+	if e.firewall == nil {
+		return
+	}
+	type forwarderCapturer interface {
+		SetPacketCapture(pc forwarder.PacketCapture)
+	}
+	if fc, ok := e.firewall.(forwarderCapturer); ok {
+		fc.SetPacketCapture(pc)
+	}
+}
+
 func (e *Engine) updateForwardRules(rules []*mgmProto.ForwardingRule) ([]firewallManager.ForwardRule, error) {
 	if e.firewall == nil {
 		log.Warn("firewall is disabled, not updating forwarding rules")

client/proto/daemon.pb.go

@@ -5969,6 +5969,288 @@ func (x *ExposeServiceReady) GetPortAutoAssigned() bool {
 	return false
 }
 
+type StartCaptureRequest struct {
+	state         protoimpl.MessageState `protogen:"open.v1"`
+	TextOutput    bool                   `protobuf:"varint,1,opt,name=text_output,json=textOutput,proto3" json:"text_output,omitempty"`
+	SnapLen       uint32                 `protobuf:"varint,2,opt,name=snap_len,json=snapLen,proto3" json:"snap_len,omitempty"`
+	Duration      *durationpb.Duration   `protobuf:"bytes,3,opt,name=duration,proto3" json:"duration,omitempty"`
+	FilterExpr    string                 `protobuf:"bytes,4,opt,name=filter_expr,json=filterExpr,proto3" json:"filter_expr,omitempty"`
+	Verbose       bool                   `protobuf:"varint,5,opt,name=verbose,proto3" json:"verbose,omitempty"`
+	Ascii         bool                   `protobuf:"varint,6,opt,name=ascii,proto3" json:"ascii,omitempty"`
+	unknownFields protoimpl.UnknownFields
+	sizeCache     protoimpl.SizeCache
+}
+
+func (x *StartCaptureRequest) Reset() {
+	*x = StartCaptureRequest{}
+	mi := &file_daemon_proto_msgTypes[90]
+	ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+	ms.StoreMessageInfo(mi)
+}
+
+func (x *StartCaptureRequest) String() string {
+	return protoimpl.X.MessageStringOf(x)
+}
+
+func (*StartCaptureRequest) ProtoMessage() {}
+
+func (x *StartCaptureRequest) ProtoReflect() protoreflect.Message {
+	mi := &file_daemon_proto_msgTypes[90]
+	if x != nil {
+		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+		if ms.LoadMessageInfo() == nil {
+			ms.StoreMessageInfo(mi)
+		}
+		return ms
+	}
+	return mi.MessageOf(x)
+}
+
+// Deprecated: Use StartCaptureRequest.ProtoReflect.Descriptor instead.
+func (*StartCaptureRequest) Descriptor() ([]byte, []int) {
+	return file_daemon_proto_rawDescGZIP(), []int{90}
+}
+
+func (x *StartCaptureRequest) GetTextOutput() bool {
+	if x != nil {
+		return x.TextOutput
+	}
+	return false
+}
+
+func (x *StartCaptureRequest) GetSnapLen() uint32 {
+	if x != nil {
+		return x.SnapLen
+	}
+	return 0
+}
+
+func (x *StartCaptureRequest) GetDuration() *durationpb.Duration {
+	if x != nil {
+		return x.Duration
+	}
+	return nil
+}
+
+func (x *StartCaptureRequest) GetFilterExpr() string {
+	if x != nil {
+		return x.FilterExpr
+	}
+	return ""
+}
+
+func (x *StartCaptureRequest) GetVerbose() bool {
+	if x != nil {
+		return x.Verbose
+	}
+	return false
+}
+
+func (x *StartCaptureRequest) GetAscii() bool {
+	if x != nil {
+		return x.Ascii
+	}
+	return false
+}
+
+type CapturePacket struct {
+	state         protoimpl.MessageState `protogen:"open.v1"`
+	Data          []byte                 `protobuf:"bytes,1,opt,name=data,proto3" json:"data,omitempty"`
+	unknownFields protoimpl.UnknownFields
+	sizeCache     protoimpl.SizeCache
+}
+
+func (x *CapturePacket) Reset() {
+	*x = CapturePacket{}
+	mi := &file_daemon_proto_msgTypes[91]
+	ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+	ms.StoreMessageInfo(mi)
+}
+
+func (x *CapturePacket) String() string {
+	return protoimpl.X.MessageStringOf(x)
+}
+
+func (*CapturePacket) ProtoMessage() {}
+
+func (x *CapturePacket) ProtoReflect() protoreflect.Message {
+	mi := &file_daemon_proto_msgTypes[91]
+	if x != nil {
+		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+		if ms.LoadMessageInfo() == nil {
+			ms.StoreMessageInfo(mi)
+		}
+		return ms
+	}
+	return mi.MessageOf(x)
+}
+
+// Deprecated: Use CapturePacket.ProtoReflect.Descriptor instead.
+func (*CapturePacket) Descriptor() ([]byte, []int) {
+	return file_daemon_proto_rawDescGZIP(), []int{91}
+}
+
+func (x *CapturePacket) GetData() []byte {
+	if x != nil {
+		return x.Data
+	}
+	return nil
+}
+
+type StartBundleCaptureRequest struct {
+	state protoimpl.MessageState `protogen:"open.v1"`
+	// timeout auto-stops the capture after this duration.
+	// Clamped to a server-side maximum (10 minutes). Zero or unset defaults to the maximum.
+	Timeout       *durationpb.Duration `protobuf:"bytes,1,opt,name=timeout,proto3" json:"timeout,omitempty"`
+	unknownFields protoimpl.UnknownFields
+	sizeCache     protoimpl.SizeCache
+}
+
+func (x *StartBundleCaptureRequest) Reset() {
+	*x = StartBundleCaptureRequest{}
+	mi := &file_daemon_proto_msgTypes[92]
+	ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+	ms.StoreMessageInfo(mi)
+}
+
+func (x *StartBundleCaptureRequest) String() string {
+	return protoimpl.X.MessageStringOf(x)
+}
+
+func (*StartBundleCaptureRequest) ProtoMessage() {}
+
+func (x *StartBundleCaptureRequest) ProtoReflect() protoreflect.Message {
+	mi := &file_daemon_proto_msgTypes[92]
+	if x != nil {
+		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+		if ms.LoadMessageInfo() == nil {
+			ms.StoreMessageInfo(mi)
+		}
+		return ms
+	}
+	return mi.MessageOf(x)
+}
+
+// Deprecated: Use StartBundleCaptureRequest.ProtoReflect.Descriptor instead.
+func (*StartBundleCaptureRequest) Descriptor() ([]byte, []int) {
+	return file_daemon_proto_rawDescGZIP(), []int{92}
+}
+
+func (x *StartBundleCaptureRequest) GetTimeout() *durationpb.Duration {
+	if x != nil {
+		return x.Timeout
+	}
+	return nil
+}
+
+type StartBundleCaptureResponse struct {
+	state         protoimpl.MessageState `protogen:"open.v1"`
+	unknownFields protoimpl.UnknownFields
+	sizeCache     protoimpl.SizeCache
+}
+
+func (x *StartBundleCaptureResponse) Reset() {
+	*x = StartBundleCaptureResponse{}
+	mi := &file_daemon_proto_msgTypes[93]
+	ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+	ms.StoreMessageInfo(mi)
+}
+
+func (x *StartBundleCaptureResponse) String() string {
+	return protoimpl.X.MessageStringOf(x)
+}
+
+func (*StartBundleCaptureResponse) ProtoMessage() {}
+
+func (x *StartBundleCaptureResponse) ProtoReflect() protoreflect.Message {
+	mi := &file_daemon_proto_msgTypes[93]
+	if x != nil {
+		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+		if ms.LoadMessageInfo() == nil {
+			ms.StoreMessageInfo(mi)
+		}
+		return ms
+	}
+	return mi.MessageOf(x)
+}
+
+// Deprecated: Use StartBundleCaptureResponse.ProtoReflect.Descriptor instead.
+func (*StartBundleCaptureResponse) Descriptor() ([]byte, []int) {
+	return file_daemon_proto_rawDescGZIP(), []int{93}
+}
+
+type StopBundleCaptureRequest struct {
+	state         protoimpl.MessageState `protogen:"open.v1"`
+	unknownFields protoimpl.UnknownFields
+	sizeCache     protoimpl.SizeCache
+}
+
+func (x *StopBundleCaptureRequest) Reset() {
+	*x = StopBundleCaptureRequest{}
+	mi := &file_daemon_proto_msgTypes[94]
+	ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+	ms.StoreMessageInfo(mi)
+}
+
+func (x *StopBundleCaptureRequest) String() string {
+	return protoimpl.X.MessageStringOf(x)
+}
+
+func (*StopBundleCaptureRequest) ProtoMessage() {}
+
+func (x *StopBundleCaptureRequest) ProtoReflect() protoreflect.Message {
+	mi := &file_daemon_proto_msgTypes[94]
+	if x != nil {
+		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+		if ms.LoadMessageInfo() == nil {
+			ms.StoreMessageInfo(mi)
+		}
+		return ms
+	}
+	return mi.MessageOf(x)
+}
+
+// Deprecated: Use StopBundleCaptureRequest.ProtoReflect.Descriptor instead.
+func (*StopBundleCaptureRequest) Descriptor() ([]byte, []int) {
+	return file_daemon_proto_rawDescGZIP(), []int{94}
+}
+
+type StopBundleCaptureResponse struct {
+	state         protoimpl.MessageState `protogen:"open.v1"`
+	unknownFields protoimpl.UnknownFields
+	sizeCache     protoimpl.SizeCache
+}
+
+func (x *StopBundleCaptureResponse) Reset() {
+	*x = StopBundleCaptureResponse{}
+	mi := &file_daemon_proto_msgTypes[95]
+	ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+	ms.StoreMessageInfo(mi)
+}
+
+func (x *StopBundleCaptureResponse) String() string {
+	return protoimpl.X.MessageStringOf(x)
+}
+
+func (*StopBundleCaptureResponse) ProtoMessage() {}
+
+func (x *StopBundleCaptureResponse) ProtoReflect() protoreflect.Message {
+	mi := &file_daemon_proto_msgTypes[95]
+	if x != nil {
+		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+		if ms.LoadMessageInfo() == nil {
+			ms.StoreMessageInfo(mi)
+		}
+		return ms
+	}
+	return mi.MessageOf(x)
+}
+
+// Deprecated: Use StopBundleCaptureResponse.ProtoReflect.Descriptor instead.
+func (*StopBundleCaptureResponse) Descriptor() ([]byte, []int) {
+	return file_daemon_proto_rawDescGZIP(), []int{95}
+}
+
 type PortInfo_Range struct {
 	state         protoimpl.MessageState `protogen:"open.v1"`
 	Start         uint32                 `protobuf:"varint,1,opt,name=start,proto3" json:"start,omitempty"`
@@ -5979,7 +6261,7 @@ type PortInfo_Range struct {
 
 func (x *PortInfo_Range) Reset() {
 	*x = PortInfo_Range{}
-	mi := &file_daemon_proto_msgTypes[91]
+	mi := &file_daemon_proto_msgTypes[97]
 	ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 	ms.StoreMessageInfo(mi)
 }
@@ -5991,7 +6273,7 @@ func (x *PortInfo_Range) String() string {
 func (*PortInfo_Range) ProtoMessage() {}
 
 func (x *PortInfo_Range) ProtoReflect() protoreflect.Message {
-	mi := &file_daemon_proto_msgTypes[91]
+	mi := &file_daemon_proto_msgTypes[97]
 	if x != nil {
 		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
 		if ms.LoadMessageInfo() == nil {
@@ -6539,7 +6821,23 @@ const file_daemon_proto_rawDesc = "" +
 	"\vservice_url\x18\x02 \x01(\tR\n" +
 	"serviceUrl\x12\x16\n" +
 	"\x06domain\x18\x03 \x01(\tR\x06domain\x12,\n" +
-	"\x12port_auto_assigned\x18\x04 \x01(\bR\x10portAutoAssigned*b\n" +
+	"\x12port_auto_assigned\x18\x04 \x01(\bR\x10portAutoAssigned\"\xd9\x01\n" +
+	"\x13StartCaptureRequest\x12\x1f\n" +
+	"\vtext_output\x18\x01 \x01(\bR\n" +
+	"textOutput\x12\x19\n" +
+	"\bsnap_len\x18\x02 \x01(\rR\asnapLen\x125\n" +
+	"\bduration\x18\x03 \x01(\v2\x19.google.protobuf.DurationR\bduration\x12\x1f\n" +
+	"\vfilter_expr\x18\x04 \x01(\tR\n" +
+	"filterExpr\x12\x18\n" +
+	"\averbose\x18\x05 \x01(\bR\averbose\x12\x14\n" +
+	"\x05ascii\x18\x06 \x01(\bR\x05ascii\"#\n" +
+	"\rCapturePacket\x12\x12\n" +
+	"\x04data\x18\x01 \x01(\fR\x04data\"P\n" +
+	"\x19StartBundleCaptureRequest\x123\n" +
+	"\atimeout\x18\x01 \x01(\v2\x19.google.protobuf.DurationR\atimeout\"\x1c\n" +
+	"\x1aStartBundleCaptureResponse\"\x1a\n" +
+	"\x18StopBundleCaptureRequest\"\x1b\n" +
+	"\x19StopBundleCaptureResponse*b\n" +
 	"\bLogLevel\x12\v\n" +
 	"\aUNKNOWN\x10\x00\x12\t\n" +
 	"\x05PANIC\x10\x01\x12\t\n" +
@@ -6557,7 +6855,7 @@ const file_daemon_proto_rawDesc = "" +
 	"\n" +
 	"EXPOSE_UDP\x10\x03\x12\x0e\n" +
 	"\n" +
-	"EXPOSE_TLS\x10\x042\xfc\x15\n" +
+	"EXPOSE_TLS\x10\x042\xff\x17\n" +
 	"\rDaemonService\x126\n" +
 	"\x05Login\x12\x14.daemon.LoginRequest\x1a\x15.daemon.LoginResponse\"\x00\x12K\n" +
 	"\fWaitSSOLogin\x12\x1b.daemon.WaitSSOLoginRequest\x1a\x1c.daemon.WaitSSOLoginResponse\"\x00\x12-\n" +
@@ -6578,7 +6876,10 @@ const file_daemon_proto_rawDesc = "" +
 	"CleanState\x12\x19.daemon.CleanStateRequest\x1a\x1a.daemon.CleanStateResponse\"\x00\x12H\n" +
 	"\vDeleteState\x12\x1a.daemon.DeleteStateRequest\x1a\x1b.daemon.DeleteStateResponse\"\x00\x12u\n" +
 	"\x1aSetSyncResponsePersistence\x12).daemon.SetSyncResponsePersistenceRequest\x1a*.daemon.SetSyncResponsePersistenceResponse\"\x00\x12H\n" +
-	"\vTracePacket\x12\x1a.daemon.TracePacketRequest\x1a\x1b.daemon.TracePacketResponse\"\x00\x12D\n" +
+	"\vTracePacket\x12\x1a.daemon.TracePacketRequest\x1a\x1b.daemon.TracePacketResponse\"\x00\x12F\n" +
+	"\fStartCapture\x12\x1b.daemon.StartCaptureRequest\x1a\x15.daemon.CapturePacket\"\x000\x01\x12]\n" +
+	"\x12StartBundleCapture\x12!.daemon.StartBundleCaptureRequest\x1a\".daemon.StartBundleCaptureResponse\"\x00\x12Z\n" +
+	"\x11StopBundleCapture\x12 .daemon.StopBundleCaptureRequest\x1a!.daemon.StopBundleCaptureResponse\"\x00\x12D\n" +
 	"\x0fSubscribeEvents\x12\x18.daemon.SubscribeRequest\x1a\x13.daemon.SystemEvent\"\x000\x01\x12B\n" +
 	"\tGetEvents\x12\x18.daemon.GetEventsRequest\x1a\x19.daemon.GetEventsResponse\"\x00\x12N\n" +
 	"\rSwitchProfile\x12\x1c.daemon.SwitchProfileRequest\x1a\x1d.daemon.SwitchProfileResponse\"\x00\x12B\n" +
@@ -6613,7 +6914,7 @@ func file_daemon_proto_rawDescGZIP() []byte {
 }
 
 var file_daemon_proto_enumTypes = make([]protoimpl.EnumInfo, 5)
-var file_daemon_proto_msgTypes = make([]protoimpl.MessageInfo, 93)
+var file_daemon_proto_msgTypes = make([]protoimpl.MessageInfo, 99)
 var file_daemon_proto_goTypes = []any{
 	(LogLevel)(0),                              // 0: daemon.LogLevel
 	(ExposeProtocol)(0),                        // 1: daemon.ExposeProtocol
@@ -6710,128 +7011,142 @@ var file_daemon_proto_goTypes = []any{
 	(*ExposeServiceRequest)(nil),               // 92: daemon.ExposeServiceRequest
 	(*ExposeServiceEvent)(nil),                 // 93: daemon.ExposeServiceEvent
 	(*ExposeServiceReady)(nil),                 // 94: daemon.ExposeServiceReady
-	nil,                                        // 95: daemon.Network.ResolvedIPsEntry
+	(*StartCaptureRequest)(nil),                // 95: daemon.StartCaptureRequest
-	(*PortInfo_Range)(nil),                     // 96: daemon.PortInfo.Range
+	(*CapturePacket)(nil),                      // 96: daemon.CapturePacket
-	nil,                                        // 97: daemon.SystemEvent.MetadataEntry
+	(*StartBundleCaptureRequest)(nil),          // 97: daemon.StartBundleCaptureRequest
-	(*durationpb.Duration)(nil),                // 98: google.protobuf.Duration
+	(*StartBundleCaptureResponse)(nil),         // 98: daemon.StartBundleCaptureResponse
-	(*timestamppb.Timestamp)(nil),              // 99: google.protobuf.Timestamp
+	(*StopBundleCaptureRequest)(nil),           // 99: daemon.StopBundleCaptureRequest
+	(*StopBundleCaptureResponse)(nil),          // 100: daemon.StopBundleCaptureResponse
+	nil,                                        // 101: daemon.Network.ResolvedIPsEntry
+	(*PortInfo_Range)(nil),                     // 102: daemon.PortInfo.Range
+	nil,                                        // 103: daemon.SystemEvent.MetadataEntry
+	(*durationpb.Duration)(nil),                // 104: google.protobuf.Duration
+	(*timestamppb.Timestamp)(nil),              // 105: google.protobuf.Timestamp
 }
 var file_daemon_proto_depIdxs = []int32{
-	2,  // 0: daemon.OSLifecycleRequest.type:type_name -> daemon.OSLifecycleRequest.CycleType
+	2,   // 0: daemon.OSLifecycleRequest.type:type_name -> daemon.OSLifecycleRequest.CycleType
-	98, // 1: daemon.LoginRequest.dnsRouteInterval:type_name -> google.protobuf.Duration
+	104, // 1: daemon.LoginRequest.dnsRouteInterval:type_name -> google.protobuf.Duration
-	28, // 2: daemon.StatusResponse.fullStatus:type_name -> daemon.FullStatus
+	28,  // 2: daemon.StatusResponse.fullStatus:type_name -> daemon.FullStatus
-	99, // 3: daemon.PeerState.connStatusUpdate:type_name -> google.protobuf.Timestamp
+	105, // 3: daemon.PeerState.connStatusUpdate:type_name -> google.protobuf.Timestamp
-	99, // 4: daemon.PeerState.lastWireguardHandshake:type_name -> google.protobuf.Timestamp
+	105, // 4: daemon.PeerState.lastWireguardHandshake:type_name -> google.protobuf.Timestamp
-	98, // 5: daemon.PeerState.latency:type_name -> google.protobuf.Duration
+	104, // 5: daemon.PeerState.latency:type_name -> google.protobuf.Duration
-	26, // 6: daemon.SSHServerState.sessions:type_name -> daemon.SSHSessionInfo
+	26,  // 6: daemon.SSHServerState.sessions:type_name -> daemon.SSHSessionInfo
-	23, // 7: daemon.FullStatus.managementState:type_name -> daemon.ManagementState
+	23,  // 7: daemon.FullStatus.managementState:type_name -> daemon.ManagementState
-	22, // 8: daemon.FullStatus.signalState:type_name -> daemon.SignalState
+	22,  // 8: daemon.FullStatus.signalState:type_name -> daemon.SignalState
-	21, // 9: daemon.FullStatus.localPeerState:type_name -> daemon.LocalPeerState
+	21,  // 9: daemon.FullStatus.localPeerState:type_name -> daemon.LocalPeerState
-	20, // 10: daemon.FullStatus.peers:type_name -> daemon.PeerState
+	20,  // 10: daemon.FullStatus.peers:type_name -> daemon.PeerState
-	24, // 11: daemon.FullStatus.relays:type_name -> daemon.RelayState
+	24,  // 11: daemon.FullStatus.relays:type_name -> daemon.RelayState
-	25, // 12: daemon.FullStatus.dns_servers:type_name -> daemon.NSGroupState
+	25,  // 12: daemon.FullStatus.dns_servers:type_name -> daemon.NSGroupState
-	58, // 13: daemon.FullStatus.events:type_name -> daemon.SystemEvent
+	58,  // 13: daemon.FullStatus.events:type_name -> daemon.SystemEvent
-	27, // 14: daemon.FullStatus.sshServerState:type_name -> daemon.SSHServerState
+	27,  // 14: daemon.FullStatus.sshServerState:type_name -> daemon.SSHServerState
-	34, // 15: daemon.ListNetworksResponse.routes:type_name -> daemon.Network
+	34,  // 15: daemon.ListNetworksResponse.routes:type_name -> daemon.Network
-	95, // 16: daemon.Network.resolvedIPs:type_name -> daemon.Network.ResolvedIPsEntry
+	101, // 16: daemon.Network.resolvedIPs:type_name -> daemon.Network.ResolvedIPsEntry
-	96, // 17: daemon.PortInfo.range:type_name -> daemon.PortInfo.Range
+	102, // 17: daemon.PortInfo.range:type_name -> daemon.PortInfo.Range
-	35, // 18: daemon.ForwardingRule.destinationPort:type_name -> daemon.PortInfo
+	35,  // 18: daemon.ForwardingRule.destinationPort:type_name -> daemon.PortInfo
-	35, // 19: daemon.ForwardingRule.translatedPort:type_name -> daemon.PortInfo
+	35,  // 19: daemon.ForwardingRule.translatedPort:type_name -> daemon.PortInfo
-	36, // 20: daemon.ForwardingRulesResponse.rules:type_name -> daemon.ForwardingRule
+	36,  // 20: daemon.ForwardingRulesResponse.rules:type_name -> daemon.ForwardingRule
-	0,  // 21: daemon.GetLogLevelResponse.level:type_name -> daemon.LogLevel
+	0,   // 21: daemon.GetLogLevelResponse.level:type_name -> daemon.LogLevel
-	0,  // 22: daemon.SetLogLevelRequest.level:type_name -> daemon.LogLevel
+	0,   // 22: daemon.SetLogLevelRequest.level:type_name -> daemon.LogLevel
-	44, // 23: daemon.ListStatesResponse.states:type_name -> daemon.State
+	44,  // 23: daemon.ListStatesResponse.states:type_name -> daemon.State
-	53, // 24: daemon.TracePacketRequest.tcp_flags:type_name -> daemon.TCPFlags
+	53,  // 24: daemon.TracePacketRequest.tcp_flags:type_name -> daemon.TCPFlags
-	55, // 25: daemon.TracePacketResponse.stages:type_name -> daemon.TraceStage
+	55,  // 25: daemon.TracePacketResponse.stages:type_name -> daemon.TraceStage
-	3,  // 26: daemon.SystemEvent.severity:type_name -> daemon.SystemEvent.Severity
+	3,   // 26: daemon.SystemEvent.severity:type_name -> daemon.SystemEvent.Severity
-	4,  // 27: daemon.SystemEvent.category:type_name -> daemon.SystemEvent.Category
+	4,   // 27: daemon.SystemEvent.category:type_name -> daemon.SystemEvent.Category
-	99, // 28: daemon.SystemEvent.timestamp:type_name -> google.protobuf.Timestamp
+	105, // 28: daemon.SystemEvent.timestamp:type_name -> google.protobuf.Timestamp
-	97, // 29: daemon.SystemEvent.metadata:type_name -> daemon.SystemEvent.MetadataEntry
+	103, // 29: daemon.SystemEvent.metadata:type_name -> daemon.SystemEvent.MetadataEntry
-	58, // 30: daemon.GetEventsResponse.events:type_name -> daemon.SystemEvent
+	58,  // 30: daemon.GetEventsResponse.events:type_name -> daemon.SystemEvent
-	98, // 31: daemon.SetConfigRequest.dnsRouteInterval:type_name -> google.protobuf.Duration
+	104, // 31: daemon.SetConfigRequest.dnsRouteInterval:type_name -> google.protobuf.Duration
-	71, // 32: daemon.ListProfilesResponse.profiles:type_name -> daemon.Profile
+	71,  // 32: daemon.ListProfilesResponse.profiles:type_name -> daemon.Profile
-	1,  // 33: daemon.ExposeServiceRequest.protocol:type_name -> daemon.ExposeProtocol
+	1,   // 33: daemon.ExposeServiceRequest.protocol:type_name -> daemon.ExposeProtocol
-	94, // 34: daemon.ExposeServiceEvent.ready:type_name -> daemon.ExposeServiceReady
+	94,  // 34: daemon.ExposeServiceEvent.ready:type_name -> daemon.ExposeServiceReady
-	33, // 35: daemon.Network.ResolvedIPsEntry.value:type_name -> daemon.IPList
+	104, // 35: daemon.StartCaptureRequest.duration:type_name -> google.protobuf.Duration
-	8,  // 36: daemon.DaemonService.Login:input_type -> daemon.LoginRequest
+	104, // 36: daemon.StartBundleCaptureRequest.timeout:type_name -> google.protobuf.Duration
-	10, // 37: daemon.DaemonService.WaitSSOLogin:input_type -> daemon.WaitSSOLoginRequest
+	33,  // 37: daemon.Network.ResolvedIPsEntry.value:type_name -> daemon.IPList
-	12, // 38: daemon.DaemonService.Up:input_type -> daemon.UpRequest
+	8,   // 38: daemon.DaemonService.Login:input_type -> daemon.LoginRequest
-	14, // 39: daemon.DaemonService.Status:input_type -> daemon.StatusRequest
+	10,  // 39: daemon.DaemonService.WaitSSOLogin:input_type -> daemon.WaitSSOLoginRequest
-	16, // 40: daemon.DaemonService.Down:input_type -> daemon.DownRequest
+	12,  // 40: daemon.DaemonService.Up:input_type -> daemon.UpRequest
-	18, // 41: daemon.DaemonService.GetConfig:input_type -> daemon.GetConfigRequest
+	14,  // 41: daemon.DaemonService.Status:input_type -> daemon.StatusRequest
-	29, // 42: daemon.DaemonService.ListNetworks:input_type -> daemon.ListNetworksRequest
+	16,  // 42: daemon.DaemonService.Down:input_type -> daemon.DownRequest
-	31, // 43: daemon.DaemonService.SelectNetworks:input_type -> daemon.SelectNetworksRequest
+	18,  // 43: daemon.DaemonService.GetConfig:input_type -> daemon.GetConfigRequest
-	31, // 44: daemon.DaemonService.DeselectNetworks:input_type -> daemon.SelectNetworksRequest
+	29,  // 44: daemon.DaemonService.ListNetworks:input_type -> daemon.ListNetworksRequest
-	5,  // 45: daemon.DaemonService.ForwardingRules:input_type -> daemon.EmptyRequest
+	31,  // 45: daemon.DaemonService.SelectNetworks:input_type -> daemon.SelectNetworksRequest
-	38, // 46: daemon.DaemonService.DebugBundle:input_type -> daemon.DebugBundleRequest
+	31,  // 46: daemon.DaemonService.DeselectNetworks:input_type -> daemon.SelectNetworksRequest
-	40, // 47: daemon.DaemonService.GetLogLevel:input_type -> daemon.GetLogLevelRequest
+	5,   // 47: daemon.DaemonService.ForwardingRules:input_type -> daemon.EmptyRequest
-	42, // 48: daemon.DaemonService.SetLogLevel:input_type -> daemon.SetLogLevelRequest
+	38,  // 48: daemon.DaemonService.DebugBundle:input_type -> daemon.DebugBundleRequest
-	45, // 49: daemon.DaemonService.ListStates:input_type -> daemon.ListStatesRequest
+	40,  // 49: daemon.DaemonService.GetLogLevel:input_type -> daemon.GetLogLevelRequest
-	47, // 50: daemon.DaemonService.CleanState:input_type -> daemon.CleanStateRequest
+	42,  // 50: daemon.DaemonService.SetLogLevel:input_type -> daemon.SetLogLevelRequest
-	49, // 51: daemon.DaemonService.DeleteState:input_type -> daemon.DeleteStateRequest
+	45,  // 51: daemon.DaemonService.ListStates:input_type -> daemon.ListStatesRequest
-	51, // 52: daemon.DaemonService.SetSyncResponsePersistence:input_type -> daemon.SetSyncResponsePersistenceRequest
+	47,  // 52: daemon.DaemonService.CleanState:input_type -> daemon.CleanStateRequest
-	54, // 53: daemon.DaemonService.TracePacket:input_type -> daemon.TracePacketRequest
+	49,  // 53: daemon.DaemonService.DeleteState:input_type -> daemon.DeleteStateRequest
-	57, // 54: daemon.DaemonService.SubscribeEvents:input_type -> daemon.SubscribeRequest
+	51,  // 54: daemon.DaemonService.SetSyncResponsePersistence:input_type -> daemon.SetSyncResponsePersistenceRequest
-	59, // 55: daemon.DaemonService.GetEvents:input_type -> daemon.GetEventsRequest
+	54,  // 55: daemon.DaemonService.TracePacket:input_type -> daemon.TracePacketRequest
-	61, // 56: daemon.DaemonService.SwitchProfile:input_type -> daemon.SwitchProfileRequest
+	95,  // 56: daemon.DaemonService.StartCapture:input_type -> daemon.StartCaptureRequest
-	63, // 57: daemon.DaemonService.SetConfig:input_type -> daemon.SetConfigRequest
+	97,  // 57: daemon.DaemonService.StartBundleCapture:input_type -> daemon.StartBundleCaptureRequest
-	65, // 58: daemon.DaemonService.AddProfile:input_type -> daemon.AddProfileRequest
+	99,  // 58: daemon.DaemonService.StopBundleCapture:input_type -> daemon.StopBundleCaptureRequest
-	67, // 59: daemon.DaemonService.RemoveProfile:input_type -> daemon.RemoveProfileRequest
+	57,  // 59: daemon.DaemonService.SubscribeEvents:input_type -> daemon.SubscribeRequest
-	69, // 60: daemon.DaemonService.ListProfiles:input_type -> daemon.ListProfilesRequest
+	59,  // 60: daemon.DaemonService.GetEvents:input_type -> daemon.GetEventsRequest
-	72, // 61: daemon.DaemonService.GetActiveProfile:input_type -> daemon.GetActiveProfileRequest
+	61,  // 61: daemon.DaemonService.SwitchProfile:input_type -> daemon.SwitchProfileRequest
-	74, // 62: daemon.DaemonService.Logout:input_type -> daemon.LogoutRequest
+	63,  // 62: daemon.DaemonService.SetConfig:input_type -> daemon.SetConfigRequest
-	76, // 63: daemon.DaemonService.GetFeatures:input_type -> daemon.GetFeaturesRequest
+	65,  // 63: daemon.DaemonService.AddProfile:input_type -> daemon.AddProfileRequest
-	78, // 64: daemon.DaemonService.TriggerUpdate:input_type -> daemon.TriggerUpdateRequest
+	67,  // 64: daemon.DaemonService.RemoveProfile:input_type -> daemon.RemoveProfileRequest
-	80, // 65: daemon.DaemonService.GetPeerSSHHostKey:input_type -> daemon.GetPeerSSHHostKeyRequest
+	69,  // 65: daemon.DaemonService.ListProfiles:input_type -> daemon.ListProfilesRequest
-	82, // 66: daemon.DaemonService.RequestJWTAuth:input_type -> daemon.RequestJWTAuthRequest
+	72,  // 66: daemon.DaemonService.GetActiveProfile:input_type -> daemon.GetActiveProfileRequest
-	84, // 67: daemon.DaemonService.WaitJWTToken:input_type -> daemon.WaitJWTTokenRequest
+	74,  // 67: daemon.DaemonService.Logout:input_type -> daemon.LogoutRequest
-	86, // 68: daemon.DaemonService.StartCPUProfile:input_type -> daemon.StartCPUProfileRequest
+	76,  // 68: daemon.DaemonService.GetFeatures:input_type -> daemon.GetFeaturesRequest
-	88, // 69: daemon.DaemonService.StopCPUProfile:input_type -> daemon.StopCPUProfileRequest
+	78,  // 69: daemon.DaemonService.TriggerUpdate:input_type -> daemon.TriggerUpdateRequest
-	6,  // 70: daemon.DaemonService.NotifyOSLifecycle:input_type -> daemon.OSLifecycleRequest
+	80,  // 70: daemon.DaemonService.GetPeerSSHHostKey:input_type -> daemon.GetPeerSSHHostKeyRequest
-	90, // 71: daemon.DaemonService.GetInstallerResult:input_type -> daemon.InstallerResultRequest
+	82,  // 71: daemon.DaemonService.RequestJWTAuth:input_type -> daemon.RequestJWTAuthRequest
-	92, // 72: daemon.DaemonService.ExposeService:input_type -> daemon.ExposeServiceRequest
+	84,  // 72: daemon.DaemonService.WaitJWTToken:input_type -> daemon.WaitJWTTokenRequest
-	9,  // 73: daemon.DaemonService.Login:output_type -> daemon.LoginResponse
+	86,  // 73: daemon.DaemonService.StartCPUProfile:input_type -> daemon.StartCPUProfileRequest
-	11, // 74: daemon.DaemonService.WaitSSOLogin:output_type -> daemon.WaitSSOLoginResponse
+	88,  // 74: daemon.DaemonService.StopCPUProfile:input_type -> daemon.StopCPUProfileRequest
-	13, // 75: daemon.DaemonService.Up:output_type -> daemon.UpResponse
+	6,   // 75: daemon.DaemonService.NotifyOSLifecycle:input_type -> daemon.OSLifecycleRequest
-	15, // 76: daemon.DaemonService.Status:output_type -> daemon.StatusResponse
+	90,  // 76: daemon.DaemonService.GetInstallerResult:input_type -> daemon.InstallerResultRequest
-	17, // 77: daemon.DaemonService.Down:output_type -> daemon.DownResponse
+	92,  // 77: daemon.DaemonService.ExposeService:input_type -> daemon.ExposeServiceRequest
-	19, // 78: daemon.DaemonService.GetConfig:output_type -> daemon.GetConfigResponse
+	9,   // 78: daemon.DaemonService.Login:output_type -> daemon.LoginResponse
-	30, // 79: daemon.DaemonService.ListNetworks:output_type -> daemon.ListNetworksResponse
+	11,  // 79: daemon.DaemonService.WaitSSOLogin:output_type -> daemon.WaitSSOLoginResponse
-	32, // 80: daemon.DaemonService.SelectNetworks:output_type -> daemon.SelectNetworksResponse
+	13,  // 80: daemon.DaemonService.Up:output_type -> daemon.UpResponse
-	32, // 81: daemon.DaemonService.DeselectNetworks:output_type -> daemon.SelectNetworksResponse
+	15,  // 81: daemon.DaemonService.Status:output_type -> daemon.StatusResponse
-	37, // 82: daemon.DaemonService.ForwardingRules:output_type -> daemon.ForwardingRulesResponse
+	17,  // 82: daemon.DaemonService.Down:output_type -> daemon.DownResponse
-	39, // 83: daemon.DaemonService.DebugBundle:output_type -> daemon.DebugBundleResponse
+	19,  // 83: daemon.DaemonService.GetConfig:output_type -> daemon.GetConfigResponse
-	41, // 84: daemon.DaemonService.GetLogLevel:output_type -> daemon.GetLogLevelResponse
+	30,  // 84: daemon.DaemonService.ListNetworks:output_type -> daemon.ListNetworksResponse
-	43, // 85: daemon.DaemonService.SetLogLevel:output_type -> daemon.SetLogLevelResponse
+	32,  // 85: daemon.DaemonService.SelectNetworks:output_type -> daemon.SelectNetworksResponse
-	46, // 86: daemon.DaemonService.ListStates:output_type -> daemon.ListStatesResponse
+	32,  // 86: daemon.DaemonService.DeselectNetworks:output_type -> daemon.SelectNetworksResponse
-	48, // 87: daemon.DaemonService.CleanState:output_type -> daemon.CleanStateResponse
+	37,  // 87: daemon.DaemonService.ForwardingRules:output_type -> daemon.ForwardingRulesResponse
-	50, // 88: daemon.DaemonService.DeleteState:output_type -> daemon.DeleteStateResponse
+	39,  // 88: daemon.DaemonService.DebugBundle:output_type -> daemon.DebugBundleResponse
-	52, // 89: daemon.DaemonService.SetSyncResponsePersistence:output_type -> daemon.SetSyncResponsePersistenceResponse
+	41,  // 89: daemon.DaemonService.GetLogLevel:output_type -> daemon.GetLogLevelResponse
-	56, // 90: daemon.DaemonService.TracePacket:output_type -> daemon.TracePacketResponse
+	43,  // 90: daemon.DaemonService.SetLogLevel:output_type -> daemon.SetLogLevelResponse
-	58, // 91: daemon.DaemonService.SubscribeEvents:output_type -> daemon.SystemEvent
+	46,  // 91: daemon.DaemonService.ListStates:output_type -> daemon.ListStatesResponse
-	60, // 92: daemon.DaemonService.GetEvents:output_type -> daemon.GetEventsResponse
+	48,  // 92: daemon.DaemonService.CleanState:output_type -> daemon.CleanStateResponse
-	62, // 93: daemon.DaemonService.SwitchProfile:output_type -> daemon.SwitchProfileResponse
+	50,  // 93: daemon.DaemonService.DeleteState:output_type -> daemon.DeleteStateResponse
-	64, // 94: daemon.DaemonService.SetConfig:output_type -> daemon.SetConfigResponse
+	52,  // 94: daemon.DaemonService.SetSyncResponsePersistence:output_type -> daemon.SetSyncResponsePersistenceResponse
-	66, // 95: daemon.DaemonService.AddProfile:output_type -> daemon.AddProfileResponse
+	56,  // 95: daemon.DaemonService.TracePacket:output_type -> daemon.TracePacketResponse
-	68, // 96: daemon.DaemonService.RemoveProfile:output_type -> daemon.RemoveProfileResponse
+	96,  // 96: daemon.DaemonService.StartCapture:output_type -> daemon.CapturePacket
-	70, // 97: daemon.DaemonService.ListProfiles:output_type -> daemon.ListProfilesResponse
+	98,  // 97: daemon.DaemonService.StartBundleCapture:output_type -> daemon.StartBundleCaptureResponse
-	73, // 98: daemon.DaemonService.GetActiveProfile:output_type -> daemon.GetActiveProfileResponse
+	100, // 98: daemon.DaemonService.StopBundleCapture:output_type -> daemon.StopBundleCaptureResponse
-	75, // 99: daemon.DaemonService.Logout:output_type -> daemon.LogoutResponse
+	58,  // 99: daemon.DaemonService.SubscribeEvents:output_type -> daemon.SystemEvent
-	77, // 100: daemon.DaemonService.GetFeatures:output_type -> daemon.GetFeaturesResponse
+	60,  // 100: daemon.DaemonService.GetEvents:output_type -> daemon.GetEventsResponse
-	79, // 101: daemon.DaemonService.TriggerUpdate:output_type -> daemon.TriggerUpdateResponse
+	62,  // 101: daemon.DaemonService.SwitchProfile:output_type -> daemon.SwitchProfileResponse
-	81, // 102: daemon.DaemonService.GetPeerSSHHostKey:output_type -> daemon.GetPeerSSHHostKeyResponse
+	64,  // 102: daemon.DaemonService.SetConfig:output_type -> daemon.SetConfigResponse
-	83, // 103: daemon.DaemonService.RequestJWTAuth:output_type -> daemon.RequestJWTAuthResponse
+	66,  // 103: daemon.DaemonService.AddProfile:output_type -> daemon.AddProfileResponse
-	85, // 104: daemon.DaemonService.WaitJWTToken:output_type -> daemon.WaitJWTTokenResponse
+	68,  // 104: daemon.DaemonService.RemoveProfile:output_type -> daemon.RemoveProfileResponse
-	87, // 105: daemon.DaemonService.StartCPUProfile:output_type -> daemon.StartCPUProfileResponse
+	70,  // 105: daemon.DaemonService.ListProfiles:output_type -> daemon.ListProfilesResponse
-	89, // 106: daemon.DaemonService.StopCPUProfile:output_type -> daemon.StopCPUProfileResponse
+	73,  // 106: daemon.DaemonService.GetActiveProfile:output_type -> daemon.GetActiveProfileResponse
-	7,  // 107: daemon.DaemonService.NotifyOSLifecycle:output_type -> daemon.OSLifecycleResponse
+	75,  // 107: daemon.DaemonService.Logout:output_type -> daemon.LogoutResponse
-	91, // 108: daemon.DaemonService.GetInstallerResult:output_type -> daemon.InstallerResultResponse
+	77,  // 108: daemon.DaemonService.GetFeatures:output_type -> daemon.GetFeaturesResponse
-	93, // 109: daemon.DaemonService.ExposeService:output_type -> daemon.ExposeServiceEvent
+	79,  // 109: daemon.DaemonService.TriggerUpdate:output_type -> daemon.TriggerUpdateResponse
-	73, // [73:110] is the sub-list for method output_type
+	81,  // 110: daemon.DaemonService.GetPeerSSHHostKey:output_type -> daemon.GetPeerSSHHostKeyResponse
-	36, // [36:73] is the sub-list for method input_type
+	83,  // 111: daemon.DaemonService.RequestJWTAuth:output_type -> daemon.RequestJWTAuthResponse
-	36, // [36:36] is the sub-list for extension type_name
+	85,  // 112: daemon.DaemonService.WaitJWTToken:output_type -> daemon.WaitJWTTokenResponse
-	36, // [36:36] is the sub-list for extension extendee
+	87,  // 113: daemon.DaemonService.StartCPUProfile:output_type -> daemon.StartCPUProfileResponse
-	0,  // [0:36] is the sub-list for field type_name
+	89,  // 114: daemon.DaemonService.StopCPUProfile:output_type -> daemon.StopCPUProfileResponse
+	7,   // 115: daemon.DaemonService.NotifyOSLifecycle:output_type -> daemon.OSLifecycleResponse
+	91,  // 116: daemon.DaemonService.GetInstallerResult:output_type -> daemon.InstallerResultResponse
+	93,  // 117: daemon.DaemonService.ExposeService:output_type -> daemon.ExposeServiceEvent
+	78,  // [78:118] is the sub-list for method output_type
+	38,  // [38:78] is the sub-list for method input_type
+	38,  // [38:38] is the sub-list for extension type_name
+	38,  // [38:38] is the sub-list for extension extendee
+	0,   // [0:38] is the sub-list for field type_name
 }
 
 func init() { file_daemon_proto_init() }
@@ -6861,7 +7176,7 @@ func file_daemon_proto_init() {
 			GoPackagePath: reflect.TypeOf(x{}).PkgPath(),
 			RawDescriptor: unsafe.Slice(unsafe.StringData(file_daemon_proto_rawDesc), len(file_daemon_proto_rawDesc)),
 			NumEnums:      5,
-			NumMessages:   93,
+			NumMessages:   99,
 			NumExtensions: 0,
 			NumServices:   1,
 		},

client/proto/daemon.proto

@@ -64,6 +64,17 @@ service DaemonService {
 
   rpc TracePacket(TracePacketRequest) returns (TracePacketResponse) {}
 
+  // StartCapture begins streaming packet capture on the WireGuard interface.
+  // Requires --enable-capture set at service install/reconfigure time.
+  rpc StartCapture(StartCaptureRequest) returns (stream CapturePacket) {}
+
+  // StartBundleCapture begins capturing packets to a server-side temp file
+  // for inclusion in the next debug bundle. Auto-stops after the given timeout.
+  rpc StartBundleCapture(StartBundleCaptureRequest) returns (StartBundleCaptureResponse) {}
+
+  // StopBundleCapture stops the running bundle capture. Idempotent.
+  rpc StopBundleCapture(StopBundleCaptureRequest) returns (StopBundleCaptureResponse) {}
+
   rpc SubscribeEvents(SubscribeRequest) returns (stream SystemEvent) {}
 
   rpc GetEvents(GetEventsRequest) returns (GetEventsResponse) {}
@@ -847,3 +858,26 @@ message ExposeServiceReady {
   string domain = 3;
   bool port_auto_assigned = 4;
 }
+
+message StartCaptureRequest {
+  bool text_output = 1;
+  uint32 snap_len = 2;
+  google.protobuf.Duration duration = 3;
+  string filter_expr = 4;
+  bool verbose = 5;
+  bool ascii = 6;
+}
+
+message CapturePacket {
+  bytes data = 1;
+}
+
+message StartBundleCaptureRequest {
+  // timeout auto-stops the capture after this duration.
+  // Clamped to a server-side maximum (10 minutes). Zero or unset defaults to the maximum.
+  google.protobuf.Duration timeout = 1;
+}
+
+message StartBundleCaptureResponse {}
+message StopBundleCaptureRequest {}
+message StopBundleCaptureResponse {}

client/proto/daemon_grpc.pb.go

@@ -53,6 +53,14 @@ type DaemonServiceClient interface {
 	// SetSyncResponsePersistence enables or disables sync response persistence
 	SetSyncResponsePersistence(ctx context.Context, in *SetSyncResponsePersistenceRequest, opts ...grpc.CallOption) (*SetSyncResponsePersistenceResponse, error)
 	TracePacket(ctx context.Context, in *TracePacketRequest, opts ...grpc.CallOption) (*TracePacketResponse, error)
+	// StartCapture begins streaming packet capture on the WireGuard interface.
+	// Requires --enable-capture set at service install/reconfigure time.
+	StartCapture(ctx context.Context, in *StartCaptureRequest, opts ...grpc.CallOption) (DaemonService_StartCaptureClient, error)
+	// StartBundleCapture begins capturing packets to a server-side temp file
+	// for inclusion in the next debug bundle. Auto-stops after the given timeout.
+	StartBundleCapture(ctx context.Context, in *StartBundleCaptureRequest, opts ...grpc.CallOption) (*StartBundleCaptureResponse, error)
+	// StopBundleCapture stops the running bundle capture. Idempotent.
+	StopBundleCapture(ctx context.Context, in *StopBundleCaptureRequest, opts ...grpc.CallOption) (*StopBundleCaptureResponse, error)
 	SubscribeEvents(ctx context.Context, in *SubscribeRequest, opts ...grpc.CallOption) (DaemonService_SubscribeEventsClient, error)
 	GetEvents(ctx context.Context, in *GetEventsRequest, opts ...grpc.CallOption) (*GetEventsResponse, error)
 	SwitchProfile(ctx context.Context, in *SwitchProfileRequest, opts ...grpc.CallOption) (*SwitchProfileResponse, error)
@@ -253,8 +261,58 @@ func (c *daemonServiceClient) TracePacket(ctx context.Context, in *TracePacketRe
 	return out, nil
 }
 
+func (c *daemonServiceClient) StartCapture(ctx context.Context, in *StartCaptureRequest, opts ...grpc.CallOption) (DaemonService_StartCaptureClient, error) {
+	stream, err := c.cc.NewStream(ctx, &DaemonService_ServiceDesc.Streams[0], "/daemon.DaemonService/StartCapture", opts...)
+	if err != nil {
+		return nil, err
+	}
+	x := &daemonServiceStartCaptureClient{stream}
+	if err := x.ClientStream.SendMsg(in); err != nil {
+		return nil, err
+	}
+	if err := x.ClientStream.CloseSend(); err != nil {
+		return nil, err
+	}
+	return x, nil
+}
+
+type DaemonService_StartCaptureClient interface {
+	Recv() (*CapturePacket, error)
+	grpc.ClientStream
+}
+
+type daemonServiceStartCaptureClient struct {
+	grpc.ClientStream
+}
+
+func (x *daemonServiceStartCaptureClient) Recv() (*CapturePacket, error) {
+	m := new(CapturePacket)
+	if err := x.ClientStream.RecvMsg(m); err != nil {
+		return nil, err
+	}
+	return m, nil
+}
+
+func (c *daemonServiceClient) StartBundleCapture(ctx context.Context, in *StartBundleCaptureRequest, opts ...grpc.CallOption) (*StartBundleCaptureResponse, error) {
+	out := new(StartBundleCaptureResponse)
+	err := c.cc.Invoke(ctx, "/daemon.DaemonService/StartBundleCapture", in, out, opts...)
+	if err != nil {
+		return nil, err
+	}
+	return out, nil
+}
+
+func (c *daemonServiceClient) StopBundleCapture(ctx context.Context, in *StopBundleCaptureRequest, opts ...grpc.CallOption) (*StopBundleCaptureResponse, error) {
+	out := new(StopBundleCaptureResponse)
+	err := c.cc.Invoke(ctx, "/daemon.DaemonService/StopBundleCapture", in, out, opts...)
+	if err != nil {
+		return nil, err
+	}
+	return out, nil
+}
+
 func (c *daemonServiceClient) SubscribeEvents(ctx context.Context, in *SubscribeRequest, opts ...grpc.CallOption) (DaemonService_SubscribeEventsClient, error) {
-	stream, err := c.cc.NewStream(ctx, &DaemonService_ServiceDesc.Streams[0], "/daemon.DaemonService/SubscribeEvents", opts...)
+	stream, err := c.cc.NewStream(ctx, &DaemonService_ServiceDesc.Streams[1], "/daemon.DaemonService/SubscribeEvents", opts...)
 	if err != nil {
 		return nil, err
 	}
@@ -439,7 +497,7 @@ func (c *daemonServiceClient) GetInstallerResult(ctx context.Context, in *Instal
 }
 
 func (c *daemonServiceClient) ExposeService(ctx context.Context, in *ExposeServiceRequest, opts ...grpc.CallOption) (DaemonService_ExposeServiceClient, error) {
-	stream, err := c.cc.NewStream(ctx, &DaemonService_ServiceDesc.Streams[1], "/daemon.DaemonService/ExposeService", opts...)
+	stream, err := c.cc.NewStream(ctx, &DaemonService_ServiceDesc.Streams[2], "/daemon.DaemonService/ExposeService", opts...)
 	if err != nil {
 		return nil, err
 	}
@@ -509,6 +567,14 @@ type DaemonServiceServer interface {
 	// SetSyncResponsePersistence enables or disables sync response persistence
 	SetSyncResponsePersistence(context.Context, *SetSyncResponsePersistenceRequest) (*SetSyncResponsePersistenceResponse, error)
 	TracePacket(context.Context, *TracePacketRequest) (*TracePacketResponse, error)
+	// StartCapture begins streaming packet capture on the WireGuard interface.
+	// Requires --enable-capture set at service install/reconfigure time.
+	StartCapture(*StartCaptureRequest, DaemonService_StartCaptureServer) error
+	// StartBundleCapture begins capturing packets to a server-side temp file
+	// for inclusion in the next debug bundle. Auto-stops after the given timeout.
+	StartBundleCapture(context.Context, *StartBundleCaptureRequest) (*StartBundleCaptureResponse, error)
+	// StopBundleCapture stops the running bundle capture. Idempotent.
+	StopBundleCapture(context.Context, *StopBundleCaptureRequest) (*StopBundleCaptureResponse, error)
 	SubscribeEvents(*SubscribeRequest, DaemonService_SubscribeEventsServer) error
 	GetEvents(context.Context, *GetEventsRequest) (*GetEventsResponse, error)
 	SwitchProfile(context.Context, *SwitchProfileRequest) (*SwitchProfileResponse, error)
@@ -598,6 +664,15 @@ func (UnimplementedDaemonServiceServer) SetSyncResponsePersistence(context.Conte
 func (UnimplementedDaemonServiceServer) TracePacket(context.Context, *TracePacketRequest) (*TracePacketResponse, error) {
 	return nil, status.Errorf(codes.Unimplemented, "method TracePacket not implemented")
 }
+func (UnimplementedDaemonServiceServer) StartCapture(*StartCaptureRequest, DaemonService_StartCaptureServer) error {
+	return status.Errorf(codes.Unimplemented, "method StartCapture not implemented")
+}
+func (UnimplementedDaemonServiceServer) StartBundleCapture(context.Context, *StartBundleCaptureRequest) (*StartBundleCaptureResponse, error) {
+	return nil, status.Errorf(codes.Unimplemented, "method StartBundleCapture not implemented")
+}
+func (UnimplementedDaemonServiceServer) StopBundleCapture(context.Context, *StopBundleCaptureRequest) (*StopBundleCaptureResponse, error) {
+	return nil, status.Errorf(codes.Unimplemented, "method StopBundleCapture not implemented")
+}
 func (UnimplementedDaemonServiceServer) SubscribeEvents(*SubscribeRequest, DaemonService_SubscribeEventsServer) error {
 	return status.Errorf(codes.Unimplemented, "method SubscribeEvents not implemented")
 }
@@ -992,6 +1067,63 @@ func _DaemonService_TracePacket_Handler(srv interface{}, ctx context.Context, de
 	return interceptor(ctx, in, info, handler)
 }
 
+func _DaemonService_StartCapture_Handler(srv interface{}, stream grpc.ServerStream) error {
+	m := new(StartCaptureRequest)
+	if err := stream.RecvMsg(m); err != nil {
+		return err
+	}
+	return srv.(DaemonServiceServer).StartCapture(m, &daemonServiceStartCaptureServer{stream})
+}
+
+type DaemonService_StartCaptureServer interface {
+	Send(*CapturePacket) error
+	grpc.ServerStream
+}
+
+type daemonServiceStartCaptureServer struct {
+	grpc.ServerStream
+}
+
+func (x *daemonServiceStartCaptureServer) Send(m *CapturePacket) error {
+	return x.ServerStream.SendMsg(m)
+}
+
+func _DaemonService_StartBundleCapture_Handler(srv interface{}, ctx context.Context, dec func(interface{}) error, interceptor grpc.UnaryServerInterceptor) (interface{}, error) {
+	in := new(StartBundleCaptureRequest)
+	if err := dec(in); err != nil {
+		return nil, err
+	}
+	if interceptor == nil {
+		return srv.(DaemonServiceServer).StartBundleCapture(ctx, in)
+	}
+	info := &grpc.UnaryServerInfo{
+		Server:     srv,
+		FullMethod: "/daemon.DaemonService/StartBundleCapture",
+	}
+	handler := func(ctx context.Context, req interface{}) (interface{}, error) {
+		return srv.(DaemonServiceServer).StartBundleCapture(ctx, req.(*StartBundleCaptureRequest))
+	}
+	return interceptor(ctx, in, info, handler)
+}
+
+func _DaemonService_StopBundleCapture_Handler(srv interface{}, ctx context.Context, dec func(interface{}) error, interceptor grpc.UnaryServerInterceptor) (interface{}, error) {
+	in := new(StopBundleCaptureRequest)
+	if err := dec(in); err != nil {
+		return nil, err
+	}
+	if interceptor == nil {
+		return srv.(DaemonServiceServer).StopBundleCapture(ctx, in)
+	}
+	info := &grpc.UnaryServerInfo{
+		Server:     srv,
+		FullMethod: "/daemon.DaemonService/StopBundleCapture",
+	}
+	handler := func(ctx context.Context, req interface{}) (interface{}, error) {
+		return srv.(DaemonServiceServer).StopBundleCapture(ctx, req.(*StopBundleCaptureRequest))
+	}
+	return interceptor(ctx, in, info, handler)
+}
+
 func _DaemonService_SubscribeEvents_Handler(srv interface{}, stream grpc.ServerStream) error {
 	m := new(SubscribeRequest)
 	if err := stream.RecvMsg(m); err != nil {
@@ -1419,6 +1551,14 @@ var DaemonService_ServiceDesc = grpc.ServiceDesc{
 			MethodName: "TracePacket",
 			Handler:    _DaemonService_TracePacket_Handler,
 		},
+		{
+			MethodName: "StartBundleCapture",
+			Handler:    _DaemonService_StartBundleCapture_Handler,
+		},
+		{
+			MethodName: "StopBundleCapture",
+			Handler:    _DaemonService_StopBundleCapture_Handler,
+		},
 		{
 			MethodName: "GetEvents",
 			Handler:    _DaemonService_GetEvents_Handler,
@@ -1489,6 +1629,11 @@ var DaemonService_ServiceDesc = grpc.ServiceDesc{
 		},
 	},
 	Streams: []grpc.StreamDesc{
+		{
+			StreamName:    "StartCapture",
+			Handler:       _DaemonService_StartCapture_Handler,
+			ServerStreams: true,
+		},
 		{
 			StreamName:    "SubscribeEvents",
 			Handler:       _DaemonService_SubscribeEvents_Handler,

client/server/capture.go

@@ -0,0 +1,325 @@
+package server
+
+import (
+	"context"
+	"io"
+	"os"
+	"sync"
+	"time"
+
+	log "github.com/sirupsen/logrus"
+	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/status"
+
+	"github.com/netbirdio/netbird/client/internal"
+	"github.com/netbirdio/netbird/client/proto"
+	"github.com/netbirdio/netbird/util/capture"
+)
+
+const maxBundleCaptureDuration = 10 * time.Minute
+
+// bundleCapture holds the state of an in-progress capture destined for the
+// debug bundle. The lifecycle is:
+//
+//	StartBundleCapture → capture running, writing to temp file
+//	StopBundleCapture  → capture stopped, temp file available
+//	DebugBundle        → temp file included in zip, then cleaned up
+type bundleCapture struct {
+	mu      sync.Mutex
+	sess    *capture.Session
+	file    *os.File
+	engine  *internal.Engine
+	cancel  context.CancelFunc
+	stopped bool
+}
+
+// stop halts the capture session and closes the pcap writer. Idempotent.
+func (bc *bundleCapture) stop() {
+	bc.mu.Lock()
+	defer bc.mu.Unlock()
+
+	if bc.stopped {
+		return
+	}
+	bc.stopped = true
+
+	if bc.cancel != nil {
+		bc.cancel()
+	}
+	if bc.engine != nil {
+		if err := bc.engine.SetCapture(nil); err != nil {
+			log.Debugf("clear bundle capture: %v", err)
+		}
+	}
+	if bc.sess != nil {
+		bc.sess.Stop()
+	}
+}
+
+// path returns the temp file path, or "" if no file exists.
+func (bc *bundleCapture) path() string {
+	if bc.file == nil {
+		return ""
+	}
+	return bc.file.Name()
+}
+
+// cleanup removes the temp file.
+func (bc *bundleCapture) cleanup() {
+	if bc.file == nil {
+		return
+	}
+	name := bc.file.Name()
+	if err := bc.file.Close(); err != nil {
+		log.Debugf("close bundle capture file: %v", err)
+	}
+	if err := os.Remove(name); err != nil && !os.IsNotExist(err) {
+		log.Debugf("remove bundle capture file: %v", err)
+	}
+	bc.file = nil
+}
+
+// StartCapture streams a pcap or text packet capture over gRPC.
+// Gated by the --enable-capture service flag.
+func (s *Server) StartCapture(req *proto.StartCaptureRequest, stream proto.DaemonService_StartCaptureServer) error {
+	if !s.captureEnabled {
+		return status.Error(codes.PermissionDenied,
+			"packet capture is disabled; reinstall or reconfigure the service with --enable-capture")
+	}
+
+	engine, err := s.getCaptureEngine()
+	if err != nil {
+		return err
+	}
+
+	matcher, err := parseCaptureFilter(req)
+	if err != nil {
+		return status.Errorf(codes.InvalidArgument, "invalid filter: %v", err)
+	}
+
+	pr, pw := io.Pipe()
+
+	opts := capture.Options{
+		Matcher: matcher,
+		SnapLen: req.GetSnapLen(),
+		Verbose: req.GetVerbose(),
+		ASCII:   req.GetAscii(),
+	}
+	if req.GetTextOutput() {
+		opts.TextOutput = pw
+	} else {
+		opts.Output = pw
+	}
+
+	sess, err := capture.NewSession(opts)
+	if err != nil {
+		pw.Close()
+		return status.Errorf(codes.Internal, "create capture session: %v", err)
+	}
+
+	if err := engine.SetCapture(sess); err != nil {
+		sess.Stop()
+		pw.Close()
+		return status.Errorf(codes.Internal, "set capture: %v", err)
+	}
+
+	// Send an empty initial message to signal that the capture was accepted.
+	// The client waits for this before printing the banner, so it must arrive
+	// before any packet data.
+	if err := stream.Send(&proto.CapturePacket{}); err != nil {
+		if clearErr := engine.SetCapture(nil); clearErr != nil {
+			log.Debugf("clear capture after send failure: %v", clearErr)
+		}
+		sess.Stop()
+		pw.Close()
+		return status.Errorf(codes.Internal, "send initial message: %v", err)
+	}
+
+	ctx := stream.Context()
+	if d := req.GetDuration(); d != nil {
+		dur := d.AsDuration()
+		if dur < 0 {
+			if clearErr := engine.SetCapture(nil); clearErr != nil {
+				log.Debugf("clear capture: %v", clearErr)
+			}
+			sess.Stop()
+			pw.Close()
+			return status.Errorf(codes.InvalidArgument, "duration must not be negative")
+		}
+		if dur > 0 {
+			var cancel context.CancelFunc
+			ctx, cancel = context.WithTimeout(ctx, dur)
+			defer cancel()
+		}
+	}
+
+	go func() {
+		<-ctx.Done()
+		if err := engine.SetCapture(nil); err != nil {
+			log.Debugf("clear capture: %v", err)
+		}
+		sess.Stop()
+		pw.Close()
+	}()
+	defer pr.Close()
+
+	log.Infof("packet capture started (text=%v, expr=%q)", req.GetTextOutput(), req.GetFilterExpr())
+	defer func() {
+		stats := sess.Stats()
+		log.Infof("packet capture stopped: %d packets, %d bytes, %d dropped",
+			stats.Packets, stats.Bytes, stats.Dropped)
+	}()
+
+	return streamToGRPC(pr, stream)
+}
+
+func streamToGRPC(r io.Reader, stream proto.DaemonService_StartCaptureServer) error {
+	buf := make([]byte, 32*1024)
+	for {
+		n, readErr := r.Read(buf)
+		if n > 0 {
+			if err := stream.Send(&proto.CapturePacket{Data: buf[:n]}); err != nil {
+				log.Debugf("capture stream send: %v", err)
+				return nil //nolint:nilerr // client disconnected
+			}
+		}
+		if readErr != nil {
+			return nil //nolint:nilerr // pipe closed, capture stopped normally
+		}
+	}
+}
+
+// StartBundleCapture begins capturing packets to a server-side temp file for
+// inclusion in the next debug bundle. Not gated by --enable-capture since the
+// output stays on the server (same trust level as CPU profiling).
+//
+// A timeout auto-stops the capture as a safety net if StopBundleCapture is
+// never called (e.g. CLI crash).
+func (s *Server) StartBundleCapture(_ context.Context, req *proto.StartBundleCaptureRequest) (*proto.StartBundleCaptureResponse, error) {
+	s.mutex.Lock()
+	defer s.mutex.Unlock()
+
+	s.stopBundleCaptureLocked()
+	s.cleanupBundleCapture()
+
+	engine, err := s.getCaptureEngineLocked()
+	if err != nil {
+		// Not fatal: kernel mode or not connected. Log and return success
+		// so the debug bundle still generates without capture data.
+		log.Warnf("packet capture unavailable, skipping: %v", err)
+		return &proto.StartBundleCaptureResponse{}, nil
+	}
+
+	timeout := req.GetTimeout().AsDuration()
+	if timeout <= 0 || timeout > maxBundleCaptureDuration {
+		timeout = maxBundleCaptureDuration
+	}
+
+	f, err := os.CreateTemp("", "netbird.capture.*.pcap")
+	if err != nil {
+		return nil, status.Errorf(codes.Internal, "create temp file: %v", err)
+	}
+
+	sess, err := capture.NewSession(capture.Options{Output: f})
+	if err != nil {
+		f.Close()
+		os.Remove(f.Name())
+		return nil, status.Errorf(codes.Internal, "create capture session: %v", err)
+	}
+
+	if err := engine.SetCapture(sess); err != nil {
+		sess.Stop()
+		f.Close()
+		os.Remove(f.Name())
+		log.Warnf("packet capture unavailable (no filtered device), skipping: %v", err)
+		return &proto.StartBundleCaptureResponse{}, nil
+	}
+
+	ctx, cancel := context.WithTimeout(context.Background(), timeout)
+	bc := &bundleCapture{
+		sess:   sess,
+		file:   f,
+		engine: engine,
+		cancel: cancel,
+	}
+
+	go func() {
+		<-ctx.Done()
+		bc.stop()
+		log.Infof("bundle capture auto-stopped after timeout")
+	}()
+
+	s.bundleCapture = bc
+	log.Infof("bundle capture started (timeout=%s, file=%s)", timeout, f.Name())
+
+	return &proto.StartBundleCaptureResponse{}, nil
+}
+
+// StopBundleCapture stops the running bundle capture. Idempotent.
+func (s *Server) StopBundleCapture(_ context.Context, _ *proto.StopBundleCaptureRequest) (*proto.StopBundleCaptureResponse, error) {
+	s.mutex.Lock()
+	defer s.mutex.Unlock()
+
+	s.stopBundleCaptureLocked()
+	return &proto.StopBundleCaptureResponse{}, nil
+}
+
+// stopBundleCaptureLocked stops the bundle capture if running. Must hold s.mutex.
+func (s *Server) stopBundleCaptureLocked() {
+	if s.bundleCapture == nil {
+		return
+	}
+	s.bundleCapture.stop()
+
+	stats := s.bundleCapture.sess.Stats()
+	log.Infof("bundle capture stopped: %d packets, %d bytes, %d dropped",
+		stats.Packets, stats.Bytes, stats.Dropped)
+}
+
+// bundleCapturePath returns the temp file path if a capture has been taken,
+// stops any running capture, and returns "". Called from DebugBundle.
+// Must hold s.mutex.
+func (s *Server) bundleCapturePath() string {
+	if s.bundleCapture == nil {
+		return ""
+	}
+
+	s.bundleCapture.stop()
+	return s.bundleCapture.path()
+}
+
+// cleanupBundleCapture removes the temp file and clears state. Must hold s.mutex.
+func (s *Server) cleanupBundleCapture() {
+	if s.bundleCapture == nil {
+		return
+	}
+	s.bundleCapture.cleanup()
+	s.bundleCapture = nil
+}
+
+func (s *Server) getCaptureEngine() (*internal.Engine, error) {
+	s.mutex.Lock()
+	defer s.mutex.Unlock()
+	return s.getCaptureEngineLocked()
+}
+
+func (s *Server) getCaptureEngineLocked() (*internal.Engine, error) {
+	if s.connectClient == nil {
+		return nil, status.Error(codes.FailedPrecondition, "client not connected")
+	}
+	engine := s.connectClient.Engine()
+	if engine == nil {
+		return nil, status.Error(codes.FailedPrecondition, "engine not initialized")
+	}
+	return engine, nil
+}
+
+// parseCaptureFilter returns a Matcher from the request.
+// Returns nil (match all) when no filter expression is set.
+func parseCaptureFilter(req *proto.StartCaptureRequest) (capture.Matcher, error) {
+	expr := req.GetFilterExpr()
+	if expr == "" {
+		return nil, nil //nolint:nilnil // nil Matcher means "match all"
+	}
+	return capture.ParseFilter(expr)
+}

client/server/debug.go

@@ -43,7 +43,9 @@ func (s *Server) DebugBundle(_ context.Context, req *proto.DebugBundleRequest) (
 		}()
 	}
 
-	// Prepare refresh callback for health probes
+	capturePath := s.bundleCapturePath()
+	defer s.cleanupBundleCapture()
+
 	var refreshStatus func()
 	if s.connectClient != nil {
 		engine := s.connectClient.Engine()
@@ -62,6 +64,7 @@ func (s *Server) DebugBundle(_ context.Context, req *proto.DebugBundleRequest) (
 			SyncResponse:   syncResponse,
 			LogPath:        s.logFile,
 			CPUProfile:     cpuProfileData,
+			CapturePath:    capturePath,
 			RefreshStatus:  refreshStatus,
 			ClientMetrics:  clientMetrics,
 		},

client/server/server.go

@@ -88,6 +88,8 @@ type Server struct {
 	profileManager         *profilemanager.ServiceManager
 	profilesDisabled       bool
 	updateSettingsDisabled bool
+	captureEnabled         bool
+	bundleCapture          *bundleCapture
 
 	sleepHandler *sleephandler.SleepHandler
 
@@ -104,7 +106,7 @@ type oauthAuthFlow struct {
 }
 
 // New server instance constructor.
-func New(ctx context.Context, logFile string, configFile string, profilesDisabled bool, updateSettingsDisabled bool) *Server {
+func New(ctx context.Context, logFile string, configFile string, profilesDisabled bool, updateSettingsDisabled bool, captureEnabled bool) *Server {
 	s := &Server{
 		rootCtx:                ctx,
 		logFile:                logFile,
@@ -113,6 +115,7 @@ func New(ctx context.Context, logFile string, configFile string, profilesDisable
 		profileManager:         profilemanager.NewServiceManager(configFile),
 		profilesDisabled:       profilesDisabled,
 		updateSettingsDisabled: updateSettingsDisabled,
+		captureEnabled:         captureEnabled,
 		jwtCache:               newJWTCache(),
 	}
 	agent := &serverAgent{s}

client/server/server_test.go

@@ -103,7 +103,7 @@ func TestConnectWithRetryRuns(t *testing.T) {
 		t.Fatalf("failed to set active profile state: %v", err)
 	}
 
-	s := New(ctx, "debug", "", false, false)
+	s := New(ctx, "debug", "", false, false, false)
 
 	s.config = config
 
@@ -164,7 +164,7 @@ func TestServer_Up(t *testing.T) {
 		t.Fatalf("failed to set active profile state: %v", err)
 	}
 
-	s := New(ctx, "console", "", false, false)
+	s := New(ctx, "console", "", false, false, false)
 	err = s.Start()
 	require.NoError(t, err)
 
@@ -234,7 +234,7 @@ func TestServer_SubcribeEvents(t *testing.T) {
 		t.Fatalf("failed to set active profile state: %v", err)
 	}
 
-	s := New(ctx, "console", "", false, false)
+	s := New(ctx, "console", "", false, false, false)
 
 	err = s.Start()
 	require.NoError(t, err)

client/server/setconfig_test.go

@@ -53,7 +53,7 @@ func TestSetConfig_AllFieldsSaved(t *testing.T) {
 	require.NoError(t, err)
 
 	ctx := context.Background()
-	s := New(ctx, "console", "", false, false)
+	s := New(ctx, "console", "", false, false, false)
 
 	rosenpassEnabled := true
 	rosenpassPermissive := true

client/ui/debug.go

@@ -16,6 +16,7 @@ import (
 	"fyne.io/fyne/v2/widget"
 	log "github.com/sirupsen/logrus"
 	"github.com/skratchdot/open-golang/open"
+	"google.golang.org/protobuf/types/known/durationpb"
 
 	"github.com/netbirdio/netbird/client/internal"
 	"github.com/netbirdio/netbird/client/proto"
@@ -38,6 +39,7 @@ type debugCollectionParams struct {
 	upload            bool
 	uploadURL         string
 	enablePersistence bool
+	capture           bool
 }
 
 // UI components for progress tracking
@@ -51,25 +53,58 @@ type progressUI struct {
 func (s *serviceClient) showDebugUI() {
 	w := s.app.NewWindow("NetBird Debug")
 	w.SetOnClosed(s.cancel)
-
 	w.Resize(fyne.NewSize(600, 500))
 	w.SetFixedSize(true)
 
 	anonymizeCheck := widget.NewCheck("Anonymize sensitive information (public IPs, domains, ...)", nil)
 	systemInfoCheck := widget.NewCheck("Include system information (routes, interfaces, ...)", nil)
 	systemInfoCheck.SetChecked(true)
+	captureCheck := widget.NewCheck("Include packet capture", nil)
 	uploadCheck := widget.NewCheck("Upload bundle automatically after creation", nil)
 	uploadCheck.SetChecked(true)
 
-	uploadURLLabel := widget.NewLabel("Debug upload URL:")
+	uploadURLContainer, uploadURL := s.buildUploadSection(uploadCheck)
+
+	debugModeContainer, runForDurationCheck, durationInput, noteLabel := s.buildDurationSection()
+
+	statusLabel := widget.NewLabel("")
+	statusLabel.Hide()
+	progressBar := widget.NewProgressBar()
+	progressBar.Hide()
+	createButton := widget.NewButton("Create Debug Bundle", nil)
+
+	uiControls := []fyne.Disableable{
+		anonymizeCheck, systemInfoCheck, captureCheck,
+		uploadCheck, uploadURL, runForDurationCheck, durationInput, createButton,
+	}
+
+	createButton.OnTapped = s.getCreateHandler(
+		statusLabel, progressBar, uploadCheck, uploadURL,
+		anonymizeCheck, systemInfoCheck, captureCheck,
+		runForDurationCheck, durationInput, uiControls, w,
+	)
+
+	content := container.NewVBox(
+		widget.NewLabel("Create a debug bundle to help troubleshoot issues with NetBird"),
+		widget.NewLabel(""),
+		anonymizeCheck, systemInfoCheck, captureCheck,
+		uploadCheck, uploadURLContainer,
+		widget.NewLabel(""),
+		debugModeContainer, noteLabel,
+		widget.NewLabel(""),
+		statusLabel, progressBar, createButton,
+	)
+
+	w.SetContent(container.NewPadded(content))
+	w.Show()
+}
+
+func (s *serviceClient) buildUploadSection(uploadCheck *widget.Check) (*fyne.Container, *widget.Entry) {
 	uploadURL := widget.NewEntry()
 	uploadURL.SetText(uptypes.DefaultBundleURL)
 	uploadURL.SetPlaceHolder("Enter upload URL")
 
-	uploadURLContainer := container.NewVBox(
+	uploadURLContainer := container.NewVBox(widget.NewLabel("Debug upload URL:"), uploadURL)
-		uploadURLLabel,
-		uploadURL,
-	)
 
 	uploadCheck.OnChanged = func(checked bool) {
 		if checked {
@@ -78,13 +113,14 @@ func (s *serviceClient) showDebugUI() {
 			uploadURLContainer.Hide()
 		}
 	}
+	return uploadURLContainer, uploadURL
+}
 
-	debugModeContainer := container.NewHBox()
+func (s *serviceClient) buildDurationSection() (*fyne.Container, *widget.Check, *widget.Entry, *widget.Label) {
 	runForDurationCheck := widget.NewCheck("Run with trace logs before creating bundle", nil)
 	runForDurationCheck.SetChecked(true)
 
 	forLabel := widget.NewLabel("for")
-
 	durationInput := widget.NewEntry()
 	durationInput.SetText("1")
 	minutesLabel := widget.NewLabel("minute")
@@ -108,63 +144,8 @@ func (s *serviceClient) showDebugUI() {
 		}
 	}
 
-	debugModeContainer.Add(runForDurationCheck)
+	modeContainer := container.NewHBox(runForDurationCheck, forLabel, durationInput, minutesLabel)
-	debugModeContainer.Add(forLabel)
+	return modeContainer, runForDurationCheck, durationInput, noteLabel
-	debugModeContainer.Add(durationInput)
-	debugModeContainer.Add(minutesLabel)
-
-	statusLabel := widget.NewLabel("")
-	statusLabel.Hide()
-
-	progressBar := widget.NewProgressBar()
-	progressBar.Hide()
-
-	createButton := widget.NewButton("Create Debug Bundle", nil)
-
-	// UI controls that should be disabled during debug collection
-	uiControls := []fyne.Disableable{
-		anonymizeCheck,
-		systemInfoCheck,
-		uploadCheck,
-		uploadURL,
-		runForDurationCheck,
-		durationInput,
-		createButton,
-	}
-
-	createButton.OnTapped = s.getCreateHandler(
-		statusLabel,
-		progressBar,
-		uploadCheck,
-		uploadURL,
-		anonymizeCheck,
-		systemInfoCheck,
-		runForDurationCheck,
-		durationInput,
-		uiControls,
-		w,
-	)
-
-	content := container.NewVBox(
-		widget.NewLabel("Create a debug bundle to help troubleshoot issues with NetBird"),
-		widget.NewLabel(""),
-		anonymizeCheck,
-		systemInfoCheck,
-		uploadCheck,
-		uploadURLContainer,
-		widget.NewLabel(""),
-		debugModeContainer,
-		noteLabel,
-		widget.NewLabel(""),
-		statusLabel,
-		progressBar,
-		createButton,
-	)
-
-	paddedContent := container.NewPadded(content)
-	w.SetContent(paddedContent)
-
-	w.Show()
 }
 
 func validateMinute(s string, minutesLabel *widget.Label) error {
@@ -200,6 +181,7 @@ func (s *serviceClient) getCreateHandler(
 	uploadURL *widget.Entry,
 	anonymizeCheck *widget.Check,
 	systemInfoCheck *widget.Check,
+	captureCheck *widget.Check,
 	runForDurationCheck *widget.Check,
 	duration *widget.Entry,
 	uiControls []fyne.Disableable,
@@ -222,6 +204,7 @@ func (s *serviceClient) getCreateHandler(
 		params := &debugCollectionParams{
 			anonymize:         anonymizeCheck.Checked,
 			systemInfo:        systemInfoCheck.Checked,
+			capture:           captureCheck.Checked,
 			upload:            uploadCheck.Checked,
 			uploadURL:         url,
 			enablePersistence: true,
@@ -253,10 +236,7 @@ func (s *serviceClient) getCreateHandler(
 
 		statusLabel.SetText("Creating debug bundle...")
 		go s.handleDebugCreation(
-			anonymizeCheck.Checked,
+			params,
-			systemInfoCheck.Checked,
-			uploadCheck.Checked,
-			url,
 			statusLabel,
 			uiControls,
 			w,
@@ -371,7 +351,7 @@ func startProgressTracker(ctx context.Context, wg *sync.WaitGroup, duration time
 func (s *serviceClient) configureServiceForDebug(
 	conn proto.DaemonServiceClient,
 	state *debugInitialState,
-	enablePersistence bool,
+	params *debugCollectionParams,
 ) {
 	if state.wasDown {
 		if _, err := conn.Up(s.ctx, &proto.UpRequest{}); err != nil {
@@ -397,7 +377,7 @@ func (s *serviceClient) configureServiceForDebug(
 		time.Sleep(time.Second)
 	}
 
-	if enablePersistence {
+	if params.enablePersistence {
 		if _, err := conn.SetSyncResponsePersistence(s.ctx, &proto.SetSyncResponsePersistenceRequest{
 			Enabled: true,
 		}); err != nil {
@@ -417,6 +397,26 @@ func (s *serviceClient) configureServiceForDebug(
 	if _, err := conn.StartCPUProfile(s.ctx, &proto.StartCPUProfileRequest{}); err != nil {
 		log.Warnf("failed to start CPU profiling: %v", err)
 	}
+
+	s.startBundleCaptureIfEnabled(conn, params)
+}
+
+func (s *serviceClient) startBundleCaptureIfEnabled(conn proto.DaemonServiceClient, params *debugCollectionParams) {
+	if !params.capture {
+		return
+	}
+
+	const maxCapture = 10 * time.Minute
+	timeout := params.duration + 30*time.Second
+	if timeout > maxCapture {
+		timeout = maxCapture
+		log.Warnf("packet capture clamped to %s (server maximum)", maxCapture)
+	}
+	if _, err := conn.StartBundleCapture(s.ctx, &proto.StartBundleCaptureRequest{
+		Timeout: durationpb.New(timeout),
+	}); err != nil {
+		log.Warnf("failed to start bundle capture: %v", err)
+	}
 }
 
 func (s *serviceClient) collectDebugData(
@@ -430,7 +430,7 @@ func (s *serviceClient) collectDebugData(
 	var wg sync.WaitGroup
 	startProgressTracker(ctx, &wg, params.duration, progress)
 
-	s.configureServiceForDebug(conn, state, params.enablePersistence)
+	s.configureServiceForDebug(conn, state, params)
 
 	wg.Wait()
 	progress.progressBar.Hide()
@@ -440,6 +440,14 @@ func (s *serviceClient) collectDebugData(
 		log.Warnf("failed to stop CPU profiling: %v", err)
 	}
 
+	if params.capture {
+		stopCtx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
+		defer cancel()
+		if _, err := conn.StopBundleCapture(stopCtx, &proto.StopBundleCaptureRequest{}); err != nil {
+			log.Warnf("failed to stop bundle capture: %v", err)
+		}
+	}
+
 	return nil
 }
 
@@ -520,18 +528,37 @@ func handleError(progress *progressUI, errMsg string) {
 }
 
 func (s *serviceClient) handleDebugCreation(
-	anonymize bool,
+	params *debugCollectionParams,
-	systemInfo bool,
-	upload bool,
-	uploadURL string,
 	statusLabel *widget.Label,
 	uiControls []fyne.Disableable,
 	w fyne.Window,
 ) {
-	log.Infof("Creating debug bundle (Anonymized: %v, System Info: %v, Upload Attempt: %v)...",
+	conn, err := s.getSrvClient(failFastTimeout)
-		anonymize, systemInfo, upload)
+	if err != nil {
+		log.Errorf("Failed to get client for debug: %v", err)
+		statusLabel.SetText(fmt.Sprintf("Error: %v", err))
+		enableUIControls(uiControls)
+		return
+	}
 
-	resp, err := s.createDebugBundle(anonymize, systemInfo, uploadURL)
+	if params.capture {
+		if _, err := conn.StartBundleCapture(s.ctx, &proto.StartBundleCaptureRequest{
+			Timeout: durationpb.New(30 * time.Second),
+		}); err != nil {
+			log.Warnf("failed to start bundle capture: %v", err)
+		} else {
+			defer func() {
+				stopCtx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
+				defer cancel()
+				if _, err := conn.StopBundleCapture(stopCtx, &proto.StopBundleCaptureRequest{}); err != nil {
+					log.Warnf("failed to stop bundle capture: %v", err)
+				}
+			}()
+			time.Sleep(2 * time.Second)
+		}
+	}
+
+	resp, err := s.createDebugBundle(params.anonymize, params.systemInfo, params.uploadURL)
 	if err != nil {
 		log.Errorf("Failed to create debug bundle: %v", err)
 		statusLabel.SetText(fmt.Sprintf("Error creating bundle: %v", err))
@@ -543,7 +570,7 @@ func (s *serviceClient) handleDebugCreation(
 	uploadFailureReason := resp.GetUploadFailureReason()
 	uploadedKey := resp.GetUploadedKey()
 
-	if upload {
+	if params.upload {
 		if uploadFailureReason != "" {
 			showUploadFailedDialog(w, localPath, uploadFailureReason)
 		} else {

client/wasm/cmd/main.go

@@ -5,6 +5,7 @@ package main
 import (
 	"context"
 	"fmt"
+	"sync"
 	"syscall/js"
 	"time"
 
@@ -14,6 +15,7 @@ import (
 	netbird "github.com/netbirdio/netbird/client/embed"
 	sshdetection "github.com/netbirdio/netbird/client/ssh/detection"
 	nbstatus "github.com/netbirdio/netbird/client/status"
+	wasmcapture "github.com/netbirdio/netbird/client/wasm/internal/capture"
 	"github.com/netbirdio/netbird/client/wasm/internal/http"
 	"github.com/netbirdio/netbird/client/wasm/internal/rdp"
 	"github.com/netbirdio/netbird/client/wasm/internal/ssh"
@@ -459,6 +461,95 @@ func createSetLogLevelMethod(client *netbird.Client) js.Func {
 	})
 }
 
+// createStartCaptureMethod creates the programmable packet capture method.
+// Returns a JS interface with onpacket callback and stop() method.
+//
+// Usage from JavaScript:
+//
+//	const cap = await client.startCapture({ filter: "tcp port 443", verbose: true })
+//	cap.onpacket = (line) => console.log(line)
+//	const stats = cap.stop()
+func createStartCaptureMethod(client *netbird.Client) js.Func {
+	return js.FuncOf(func(_ js.Value, args []js.Value) any {
+		var opts js.Value
+		if len(args) > 0 {
+			opts = args[0]
+		}
+
+		return createPromise(func(resolve, reject js.Value) {
+			iface, err := wasmcapture.Start(client, opts)
+			if err != nil {
+				reject.Invoke(js.ValueOf(fmt.Sprintf("start capture: %v", err)))
+				return
+			}
+			resolve.Invoke(iface)
+		})
+	})
+}
+
+// captureMethods returns capture() and stopCapture() that share state for
+// the console-log shortcut. capture() logs packets to the browser console
+// and stopCapture() ends it, like Ctrl+C on the CLI.
+//
+// Usage from browser devtools console:
+//
+//	await client.capture()              // capture all packets
+//	await client.capture("tcp")         // capture with filter
+//	await client.capture({filter: "host 10.0.0.1", verbose: true})
+//	client.stopCapture()                // stop and print stats
+func captureMethods(client *netbird.Client) (startFn, stopFn js.Func) {
+	var mu sync.Mutex
+	var active *wasmcapture.Handle
+
+	startFn = js.FuncOf(func(_ js.Value, args []js.Value) any {
+		var opts js.Value
+		if len(args) > 0 {
+			opts = args[0]
+		}
+
+		return createPromise(func(resolve, reject js.Value) {
+			mu.Lock()
+			defer mu.Unlock()
+
+			if active != nil {
+				active.Stop()
+				active = nil
+			}
+
+			h, err := wasmcapture.StartConsole(client, opts)
+			if err != nil {
+				reject.Invoke(js.ValueOf(fmt.Sprintf("start capture: %v", err)))
+				return
+			}
+			active = h
+
+			console := js.Global().Get("console")
+			console.Call("log", "[capture] started, call client.stopCapture() to stop")
+			resolve.Invoke(js.Undefined())
+		})
+	})
+
+	stopFn = js.FuncOf(func(_ js.Value, _ []js.Value) any {
+		mu.Lock()
+		defer mu.Unlock()
+
+		if active == nil {
+			js.Global().Get("console").Call("log", "[capture] no active capture")
+			return js.Undefined()
+		}
+
+		stats := active.Stop()
+		active = nil
+
+		console := js.Global().Get("console")
+		console.Call("log", fmt.Sprintf("[capture] stopped: %d packets, %d bytes, %d dropped",
+			stats.Packets, stats.Bytes, stats.Dropped))
+		return js.Undefined()
+	})
+
+	return startFn, stopFn
+}
+
 // createPromise is a helper to create JavaScript promises
 func createPromise(handler func(resolve, reject js.Value)) js.Value {
 	return js.Global().Get("Promise").New(js.FuncOf(func(_ js.Value, promiseArgs []js.Value) any {
@@ -521,6 +612,11 @@ func createClientObject(client *netbird.Client) js.Value {
 	obj["statusDetail"] = createStatusDetailMethod(client)
 	obj["getSyncResponse"] = createGetSyncResponseMethod(client)
 	obj["setLogLevel"] = createSetLogLevelMethod(client)
+	obj["startCapture"] = createStartCaptureMethod(client)
+
+	capStart, capStop := captureMethods(client)
+	obj["capture"] = capStart
+	obj["stopCapture"] = capStop
 
 	return js.ValueOf(obj)
 }

client/wasm/internal/capture/capture.go

@@ -0,0 +1,211 @@
+//go:build js
+
+// Package capture bridges the util/capture package to JavaScript via syscall/js.
+package capture
+
+import (
+	"strings"
+	"sync"
+	"syscall/js"
+
+	log "github.com/sirupsen/logrus"
+
+	netbird "github.com/netbirdio/netbird/client/embed"
+	"github.com/netbirdio/netbird/util/capture"
+)
+
+// Handle holds a running capture session and the embedded client reference
+// so it can be stopped later.
+type Handle struct {
+	client  *netbird.Client
+	sess    *capture.Session
+	stopFn  js.Func
+	stopped bool
+}
+
+// Stop ends the capture and returns stats.
+func (h *Handle) Stop() capture.Stats {
+	if h.stopped {
+		return h.sess.Stats()
+	}
+	h.stopped = true
+	h.stopFn.Release()
+
+	if err := h.client.SetCapture(nil); err != nil {
+		log.Debugf("clear capture: %v", err)
+	}
+	h.sess.Stop()
+	return h.sess.Stats()
+}
+
+func statsToJS(s capture.Stats) js.Value {
+	obj := js.Global().Get("Object").Call("create", js.Null())
+	obj.Set("packets", js.ValueOf(s.Packets))
+	obj.Set("bytes", js.ValueOf(s.Bytes))
+	obj.Set("dropped", js.ValueOf(s.Dropped))
+	return obj
+}
+
+// parseOpts extracts filter/verbose/ascii from a JS options value.
+func parseOpts(jsOpts js.Value) (filter string, verbose, ascii bool) {
+	if jsOpts.IsNull() || jsOpts.IsUndefined() {
+		return
+	}
+	if jsOpts.Type() == js.TypeString {
+		filter = jsOpts.String()
+		return
+	}
+	if jsOpts.Type() != js.TypeObject {
+		return
+	}
+	if f := jsOpts.Get("filter"); !f.IsUndefined() && !f.IsNull() {
+		filter = f.String()
+	}
+	if v := jsOpts.Get("verbose"); !v.IsUndefined() {
+		verbose = v.Truthy()
+	}
+	if a := jsOpts.Get("ascii"); !a.IsUndefined() {
+		ascii = a.Truthy()
+	}
+	return
+}
+
+func buildMatcher(filter string) (capture.Matcher, error) {
+	if filter == "" {
+		return nil, nil
+	}
+	return capture.ParseFilter(filter)
+}
+
+// Start creates a capture session and returns a JS interface for streaming text
+// output. The returned object exposes:
+//
+//	onpacket(callback)  - set callback(string) for each text line
+//	stop()              - stop capture and return stats { packets, bytes, dropped }
+//
+// Options: { filter: string, verbose: bool, ascii: bool } or just a filter string.
+func Start(client *netbird.Client, jsOpts js.Value) (js.Value, error) {
+	filter, verbose, ascii := parseOpts(jsOpts)
+
+	matcher, err := buildMatcher(filter)
+	if err != nil {
+		return js.Undefined(), err
+	}
+
+	cb := &jsCallbackWriter{}
+
+	sess, err := capture.NewSession(capture.Options{
+		TextOutput: cb,
+		Matcher:    matcher,
+		Verbose:    verbose,
+		ASCII:      ascii,
+	})
+	if err != nil {
+		return js.Undefined(), err
+	}
+
+	if err := client.SetCapture(sess); err != nil {
+		sess.Stop()
+		return js.Undefined(), err
+	}
+
+	handle := &Handle{client: client, sess: sess}
+
+	iface := js.Global().Get("Object").Call("create", js.Null())
+	handle.stopFn = js.FuncOf(func(_ js.Value, _ []js.Value) any {
+		return statsToJS(handle.Stop())
+	})
+	iface.Set("stop", handle.stopFn)
+	iface.Set("onpacket", js.Undefined())
+	cb.setInterface(iface)
+
+	return iface, nil
+}
+
+// StartConsole starts a capture that logs every packet line to console.log.
+// Returns a Handle so the caller can stop it later.
+func StartConsole(client *netbird.Client, jsOpts js.Value) (*Handle, error) {
+	filter, verbose, ascii := parseOpts(jsOpts)
+
+	matcher, err := buildMatcher(filter)
+	if err != nil {
+		return nil, err
+	}
+
+	cb := &jsCallbackWriter{}
+
+	sess, err := capture.NewSession(capture.Options{
+		TextOutput: cb,
+		Matcher:    matcher,
+		Verbose:    verbose,
+		ASCII:      ascii,
+	})
+	if err != nil {
+		return nil, err
+	}
+
+	if err := client.SetCapture(sess); err != nil {
+		sess.Stop()
+		return nil, err
+	}
+
+	handle := &Handle{client: client, sess: sess}
+	handle.stopFn = js.FuncOf(func(_ js.Value, _ []js.Value) any {
+		return statsToJS(handle.Stop())
+	})
+
+	iface := js.Global().Get("Object").Call("create", js.Null())
+	console := js.Global().Get("console")
+	iface.Set("onpacket", console.Get("log").Call("bind", console, js.ValueOf("[capture]")))
+	cb.setInterface(iface)
+
+	return handle, nil
+}
+
+// jsCallbackWriter is an io.Writer that buffers text until a newline, then
+// invokes the JS onpacket callback with each complete line.
+type jsCallbackWriter struct {
+	mu    sync.Mutex
+	iface js.Value
+	buf   strings.Builder
+}
+
+func (w *jsCallbackWriter) setInterface(iface js.Value) {
+	w.mu.Lock()
+	defer w.mu.Unlock()
+	w.iface = iface
+}
+
+func (w *jsCallbackWriter) Write(p []byte) (int, error) {
+	w.mu.Lock()
+	w.buf.Write(p)
+
+	var lines []string
+	for {
+		str := w.buf.String()
+		idx := strings.IndexByte(str, '\n')
+		if idx < 0 {
+			break
+		}
+		lines = append(lines, str[:idx])
+		w.buf.Reset()
+		if idx+1 < len(str) {
+			w.buf.WriteString(str[idx+1:])
+		}
+	}
+
+	iface := w.iface
+	w.mu.Unlock()
+
+	if iface.IsUndefined() {
+		return len(p), nil
+	}
+	cb := iface.Get("onpacket")
+	if cb.IsUndefined() || cb.IsNull() {
+		return len(p), nil
+	}
+	for _, line := range lines {
+		cb.Invoke(js.ValueOf(line))
+	}
+	return len(p), nil
+}

proxy/cmd/proxy/cmd/debug.go

@@ -2,7 +2,12 @@ package cmd
 
 import (
 	"fmt"
+	"os"
+	"os/signal"
+	"path/filepath"
 	"strconv"
+	"strings"
+	"syscall"
 
 	"github.com/spf13/cobra"
 
@@ -99,6 +104,27 @@ var debugStopCmd = &cobra.Command{
 	SilenceUsage: true,
 }
 
+var debugCaptureCmd = &cobra.Command{
+	Use:   "capture <account-id> [filter expression]",
+	Short: "Capture packets on a client's WireGuard interface",
+	Long: `Captures decrypted packets flowing through a client's WireGuard interface.
+
+Default output is human-readable text. Use --pcap or --output for pcap binary.
+Filter arguments after the account ID use BPF-like syntax.
+
+Examples:
+  netbird-proxy debug capture <account-id>
+  netbird-proxy debug capture <account-id> --duration 1m host 10.0.0.1
+  netbird-proxy debug capture <account-id> host 10.0.0.1 and tcp port 443
+  netbird-proxy debug capture <account-id> not port 22
+  netbird-proxy debug capture <account-id> -o capture.pcap
+  netbird-proxy debug capture <account-id> --pcap | tcpdump -r - -n
+  netbird-proxy debug capture <account-id> --pcap | tshark -r -`,
+	Args:         cobra.MinimumNArgs(1),
+	RunE:         runDebugCapture,
+	SilenceUsage: true,
+}
+
 func init() {
 	debugCmd.PersistentFlags().StringVar(&debugAddr, "addr", envStringOrDefault("NB_PROXY_DEBUG_ADDRESS", "localhost:8444"), "Debug endpoint address")
 	debugCmd.PersistentFlags().BoolVar(&jsonOutput, "json", false, "Output JSON instead of pretty format")
@@ -110,6 +136,12 @@ func init() {
 
 	debugPingCmd.Flags().StringVar(&pingTimeout, "timeout", "", "Ping timeout (e.g., 10s)")
 
+	debugCaptureCmd.Flags().DurationP("duration", "d", 0, "Capture duration (0 = server default)")
+	debugCaptureCmd.Flags().Bool("pcap", false, "Force pcap binary output (default when --output is set)")
+	debugCaptureCmd.Flags().BoolP("verbose", "v", false, "Show seq/ack, TTL, window, total length (text mode)")
+	debugCaptureCmd.Flags().Bool("ascii", false, "Print payload as ASCII after each packet (text mode)")
+	debugCaptureCmd.Flags().StringP("output", "o", "", "Write pcap to file instead of stdout")
+
 	debugCmd.AddCommand(debugHealthCmd)
 	debugCmd.AddCommand(debugClientsCmd)
 	debugCmd.AddCommand(debugStatusCmd)
@@ -119,6 +151,7 @@ func init() {
 	debugCmd.AddCommand(debugLogCmd)
 	debugCmd.AddCommand(debugStartCmd)
 	debugCmd.AddCommand(debugStopCmd)
+	debugCmd.AddCommand(debugCaptureCmd)
 
 	rootCmd.AddCommand(debugCmd)
 }
@@ -171,3 +204,84 @@ func runDebugStart(cmd *cobra.Command, args []string) error {
 func runDebugStop(cmd *cobra.Command, args []string) error {
 	return getDebugClient(cmd).StopClient(cmd.Context(), args[0])
 }
+
+func runDebugCapture(cmd *cobra.Command, args []string) error {
+	duration, _ := cmd.Flags().GetDuration("duration")
+	forcePcap, _ := cmd.Flags().GetBool("pcap")
+	verbose, _ := cmd.Flags().GetBool("verbose")
+	ascii, _ := cmd.Flags().GetBool("ascii")
+	outPath, _ := cmd.Flags().GetString("output")
+
+	// Default to text. Use pcap when --pcap is set or --output is given.
+	wantText := !forcePcap && outPath == ""
+
+	var filterExpr string
+	if len(args) > 1 {
+		filterExpr = strings.Join(args[1:], " ")
+	}
+
+	ctx, cancel := signal.NotifyContext(cmd.Context(), syscall.SIGINT, syscall.SIGTERM)
+	defer cancel()
+
+	out, cleanup, err := captureOutputWriter(cmd, outPath)
+	if err != nil {
+		return err
+	}
+	defer cleanup()
+
+	if wantText {
+		cmd.PrintErrln("Capturing packets... Press Ctrl+C to stop.")
+	} else {
+		cmd.PrintErrln("Capturing packets (pcap)... Press Ctrl+C to stop.")
+	}
+
+	var durationStr string
+	if duration > 0 {
+		durationStr = duration.String()
+	}
+
+	err = getDebugClient(cmd).Capture(ctx, debug.CaptureOptions{
+		AccountID:  args[0],
+		Duration:   durationStr,
+		FilterExpr: filterExpr,
+		Text:       wantText,
+		Verbose:    verbose,
+		ASCII:      ascii,
+		Output:     out,
+	})
+	if err != nil {
+		return err
+	}
+
+	cmd.PrintErrln("\nCapture finished.")
+	return nil
+}
+
+// captureOutputWriter returns the writer and cleanup function for capture output.
+func captureOutputWriter(cmd *cobra.Command, outPath string) (out *os.File, cleanup func(), err error) {
+	if outPath != "" {
+		f, err := os.CreateTemp(filepath.Dir(outPath), filepath.Base(outPath)+".*.tmp")
+		if err != nil {
+			return nil, nil, fmt.Errorf("create output file: %w", err)
+		}
+		tmpPath := f.Name()
+		return f, func() {
+			if err := f.Close(); err != nil {
+				cmd.PrintErrf("close output file: %v\n", err)
+			}
+			if fi, err := os.Stat(tmpPath); err == nil && fi.Size() > 0 {
+				if err := os.Rename(tmpPath, outPath); err != nil {
+					cmd.PrintErrf("rename output file: %v\n", err)
+				} else {
+					cmd.PrintErrf("Wrote %s\n", outPath)
+				}
+			} else {
+				os.Remove(tmpPath)
+			}
+		}, nil
+	}
+
+	return os.Stdout, func() {
+		// no cleanup needed for stdout
+	}, nil
+}

proxy/internal/debug/client.go

@@ -310,6 +310,76 @@ func (c *Client) printError(data map[string]any) {
 	}
 }
 
+// CaptureOptions configures a capture request.
+type CaptureOptions struct {
+	AccountID  string
+	Duration   string
+	FilterExpr string
+	Text       bool
+	Verbose    bool
+	ASCII      bool
+	Output     io.Writer
+}
+
+// Capture streams a packet capture from the debug endpoint. The response body
+// (pcap or text) is written directly to opts.Output until the server closes the
+// connection or the context is cancelled.
+func (c *Client) Capture(ctx context.Context, opts CaptureOptions) error {
+	if opts.AccountID == "" {
+		return fmt.Errorf("account ID is required")
+	}
+	if opts.Output == nil {
+		return fmt.Errorf("output writer is required")
+	}
+
+	params := url.Values{}
+	if opts.Duration != "" {
+		params.Set("duration", opts.Duration)
+	}
+	if opts.FilterExpr != "" {
+		params.Set("filter", opts.FilterExpr)
+	}
+	if opts.Text {
+		params.Set("format", "text")
+	}
+	if opts.Verbose {
+		params.Set("verbose", "true")
+	}
+	if opts.ASCII {
+		params.Set("ascii", "true")
+	}
+
+	path := fmt.Sprintf("/debug/clients/%s/capture", url.PathEscape(opts.AccountID))
+	if len(params) > 0 {
+		path += "?" + params.Encode()
+	}
+
+	fullURL := c.baseURL + path
+	req, err := http.NewRequestWithContext(ctx, http.MethodGet, fullURL, nil)
+	if err != nil {
+		return fmt.Errorf("create request: %w", err)
+	}
+
+	// Use a separate client without timeout since captures stream for their full duration.
+	httpClient := &http.Client{}
+	resp, err := httpClient.Do(req)
+	if err != nil {
+		return fmt.Errorf("request failed: %w", err)
+	}
+	defer func() { _ = resp.Body.Close() }()
+
+	if resp.StatusCode >= 400 {
+		body, _ := io.ReadAll(resp.Body)
+		return fmt.Errorf("server error (%d): %s", resp.StatusCode, strings.TrimSpace(string(body)))
+	}
+
+	_, err = io.Copy(opts.Output, resp.Body)
+	if err != nil && ctx.Err() != nil {
+		return nil
+	}
+	return err
+}
+
 func (c *Client) fetchAndPrint(ctx context.Context, path string, printer func(map[string]any)) error {
 	data, raw, err := c.fetch(ctx, path)
 	if err != nil {

proxy/internal/debug/handler.go

@@ -24,6 +24,7 @@ import (
 	"github.com/netbirdio/netbird/proxy/internal/health"
 	"github.com/netbirdio/netbird/proxy/internal/roundtrip"
 	"github.com/netbirdio/netbird/proxy/internal/types"
+	"github.com/netbirdio/netbird/util/capture"
 	"github.com/netbirdio/netbird/version"
 )
 
@@ -174,6 +175,8 @@ func (h *Handler) handleClientRoutes(w http.ResponseWriter, r *http.Request, pat
 		h.handleClientStart(w, r, accountID)
 	case "stop":
 		h.handleClientStop(w, r, accountID)
+	case "capture":
+		h.handleCapture(w, r, accountID)
 	default:
 		return false
 	}
@@ -632,6 +635,99 @@ func (h *Handler) handleClientStop(w http.ResponseWriter, r *http.Request, accou
 	})
 }
 
+const maxCaptureDuration = 30 * time.Minute
+
+// handleCapture streams a pcap or text packet capture for the given client.
+//
+// Query params:
+//
+//	duration: capture duration (0 or absent = max, capped at 30m)
+//	format:   "text" for human-readable output (default: pcap)
+//	filter:   BPF-like filter expression (e.g. "host 10.0.0.1 and tcp port 443")
+func (h *Handler) handleCapture(w http.ResponseWriter, r *http.Request, accountID types.AccountID) {
+	client, ok := h.provider.GetClient(accountID)
+	if !ok {
+		http.Error(w, "client not found", http.StatusNotFound)
+		return
+	}
+
+	duration := maxCaptureDuration
+	if durationStr := r.URL.Query().Get("duration"); durationStr != "" {
+		d, err := time.ParseDuration(durationStr)
+		if err != nil {
+			http.Error(w, "invalid duration: "+err.Error(), http.StatusBadRequest)
+			return
+		}
+		if d < 0 {
+			http.Error(w, "duration must not be negative", http.StatusBadRequest)
+			return
+		}
+		if d > 0 {
+			duration = min(d, maxCaptureDuration)
+		}
+	}
+
+	var matcher capture.Matcher
+	if expr := r.URL.Query().Get("filter"); expr != "" {
+		var err error
+		matcher, err = capture.ParseFilter(expr)
+		if err != nil {
+			http.Error(w, "invalid filter: "+err.Error(), http.StatusBadRequest)
+			return
+		}
+	}
+
+	wantText := r.URL.Query().Get("format") == "text"
+	verbose := r.URL.Query().Get("verbose") == "true"
+	ascii := r.URL.Query().Get("ascii") == "true"
+
+	opts := capture.Options{Matcher: matcher, Verbose: verbose, ASCII: ascii}
+	if wantText {
+		w.Header().Set("Content-Type", "text/plain; charset=utf-8")
+		opts.TextOutput = w
+	} else {
+		w.Header().Set("Content-Type", "application/vnd.tcpdump.pcap")
+		w.Header().Set("Content-Disposition",
+			fmt.Sprintf("attachment; filename=capture-%s.pcap", accountID))
+		opts.Output = w
+	}
+
+	sess, err := capture.NewSession(opts)
+	if err != nil {
+		http.Error(w, "create capture session: "+err.Error(), http.StatusInternalServerError)
+		return
+	}
+	defer sess.Stop()
+
+	if err := client.SetCapture(sess); err != nil {
+		http.Error(w, "set capture: "+err.Error(), http.StatusServiceUnavailable)
+		return
+	}
+	defer client.SetCapture(nil) //nolint:errcheck
+
+	// Flush headers after setup succeeds so errors above can still set status codes.
+	if f, ok := w.(http.Flusher); ok {
+		f.Flush()
+	}
+
+	timer := time.NewTimer(duration)
+	defer timer.Stop()
+
+	select {
+	case <-r.Context().Done():
+	case <-timer.C:
+	}
+
+	if err := client.SetCapture(nil); err != nil {
+		h.logger.Debugf("clear capture: %v", err)
+	}
+	sess.Stop()
+
+	stats := sess.Stats()
+	h.logger.Infof("capture for %s finished: %d packets, %d bytes, %d dropped",
+		accountID, stats.Packets, stats.Bytes, stats.Dropped)
+}
+
 func (h *Handler) handleHealth(w http.ResponseWriter, r *http.Request, wantJSON bool) {
 	if !wantJSON {
 		http.Redirect(w, r, "/debug", http.StatusSeeOther)

util/capture/afpacket_linux.go

@@ -0,0 +1,193 @@
+package capture
+
+import (
+	"encoding/binary"
+	"errors"
+	"fmt"
+	"net"
+	"sync"
+	"sync/atomic"
+
+	log "github.com/sirupsen/logrus"
+	"golang.org/x/sys/unix"
+)
+
+// htons converts a uint16 from host to network (big-endian) byte order.
+func htons(v uint16) uint16 {
+	var buf [2]byte
+	binary.BigEndian.PutUint16(buf[:], v)
+	return binary.NativeEndian.Uint16(buf[:])
+}
+
+// AFPacketCapture reads raw packets from a network interface using an
+// AF_PACKET socket. This is the kernel-mode fallback when FilteredDevice is
+// not available (kernel WireGuard). Linux only.
+//
+// It implements device.PacketCapture so it can be set on a Session, but it
+// drives its own read loop rather than being called from FilteredDevice.
+// Call Start to begin and Stop to end.
+type AFPacketCapture struct {
+	ifaceName string
+	sess      *Session
+	fd        int
+	mu        sync.Mutex
+	stopped   chan struct{}
+	started   atomic.Bool
+	closed    atomic.Bool
+}
+
+// NewAFPacketCapture creates a capture bound to the given interface.
+// The session receives packets via Offer.
+func NewAFPacketCapture(ifaceName string, sess *Session) *AFPacketCapture {
+	return &AFPacketCapture{
+		ifaceName: ifaceName,
+		sess:      sess,
+		fd:        -1,
+		stopped:   make(chan struct{}),
+	}
+}
+
+// Start opens the AF_PACKET socket and begins reading packets.
+// Packets are fed to the session via Offer. Returns immediately;
+// the read loop runs in a goroutine.
+func (c *AFPacketCapture) Start() error {
+	if c.sess == nil {
+		return errors.New("nil capture session")
+	}
+	if c.started.Load() {
+		return errors.New("capture already started")
+	}
+
+	iface, err := net.InterfaceByName(c.ifaceName)
+	if err != nil {
+		return fmt.Errorf("interface %s: %w", c.ifaceName, err)
+	}
+
+	fd, err := unix.Socket(unix.AF_PACKET, unix.SOCK_DGRAM|unix.SOCK_NONBLOCK|unix.SOCK_CLOEXEC, int(htons(unix.ETH_P_ALL)))
+	if err != nil {
+		return fmt.Errorf("create AF_PACKET socket: %w", err)
+	}
+
+	addr := &unix.SockaddrLinklayer{
+		Protocol: htons(unix.ETH_P_ALL),
+		Ifindex:  iface.Index,
+	}
+	if err := unix.Bind(fd, addr); err != nil {
+		unix.Close(fd)
+		return fmt.Errorf("bind to %s: %w", c.ifaceName, err)
+	}
+
+	c.mu.Lock()
+	c.fd = fd
+	c.mu.Unlock()
+
+	c.started.Store(true)
+	go c.readLoop(fd)
+	return nil
+}
+
+// Stop closes the socket and waits for the read loop to exit. Idempotent.
+func (c *AFPacketCapture) Stop() {
+	if !c.closed.CompareAndSwap(false, true) {
+		if c.started.Load() {
+			<-c.stopped
+		}
+		return
+	}
+
+	c.mu.Lock()
+	fd := c.fd
+	c.fd = -1
+	c.mu.Unlock()
+
+	if fd >= 0 {
+		unix.Close(fd)
+	}
+
+	if c.started.Load() {
+		<-c.stopped
+	}
+}
+
+func (c *AFPacketCapture) readLoop(fd int) {
+	defer close(c.stopped)
+
+	buf := make([]byte, 65536)
+	pollFds := []unix.PollFd{{Fd: int32(fd), Events: unix.POLLIN}}
+
+	for {
+		if c.closed.Load() {
+			return
+		}
+
+		ok, err := c.pollOnce(pollFds)
+		if err != nil {
+			return
+		}
+		if !ok {
+			continue
+		}
+
+		c.recvAndOffer(fd, buf)
+	}
+}
+
+// pollOnce waits for data on the fd. Returns true if data is ready, false for timeout/retry.
+// Returns an error to signal the loop should exit.
+func (c *AFPacketCapture) pollOnce(pollFds []unix.PollFd) (bool, error) {
+	n, err := unix.Poll(pollFds, 200)
+	if err != nil {
+		if errors.Is(err, unix.EINTR) {
+			return false, nil
+		}
+		if c.closed.Load() {
+			return false, errors.New("closed")
+		}
+		log.Debugf("af_packet poll: %v", err)
+		return false, err
+	}
+	if n == 0 {
+		return false, nil
+	}
+	if pollFds[0].Revents&(unix.POLLERR|unix.POLLHUP|unix.POLLNVAL) != 0 {
+		return false, errors.New("fd error")
+	}
+	return true, nil
+}
+
+func (c *AFPacketCapture) recvAndOffer(fd int, buf []byte) {
+	nr, from, err := unix.Recvfrom(fd, buf, 0)
+	if err != nil {
+		if errors.Is(err, unix.EAGAIN) || errors.Is(err, unix.EINTR) {
+			return
+		}
+		if !c.closed.Load() {
+			log.Debugf("af_packet recvfrom: %v", err)
+		}
+		return
+	}
+	if nr < 1 {
+		return
+	}
+
+	ver := buf[0] >> 4
+	if ver != 4 && ver != 6 {
+		return
+	}
+
+	// The kernel sets Pkttype on AF_PACKET sockets:
+	//   PACKET_HOST(0)     = addressed to us (inbound)
+	//   PACKET_OUTGOING(4) = sent by us (outbound)
+	outbound := false
+	if sa, ok := from.(*unix.SockaddrLinklayer); ok {
+		outbound = sa.Pkttype == unix.PACKET_OUTGOING
+	}
+	c.sess.Offer(buf[:nr], outbound)
+}
+
+// Offer satisfies device.PacketCapture but is unused: the AFPacketCapture
+// drives its own read loop. This exists only so the type signature is
+// compatible if someone tries to set it as a PacketCapture.
+func (c *AFPacketCapture) Offer([]byte, bool) {
+	// unused: AFPacketCapture drives its own read loop
+}

util/capture/afpacket_stub.go

@@ -0,0 +1,26 @@
+//go:build !linux
+
+package capture
+
+import "errors"
+
+// AFPacketCapture is not available on this platform.
+type AFPacketCapture struct{}
+
+// NewAFPacketCapture returns nil on non-Linux platforms.
+func NewAFPacketCapture(string, *Session) *AFPacketCapture { return nil }
+
+// Start returns an error on non-Linux platforms.
+func (c *AFPacketCapture) Start() error {
+	return errors.New("AF_PACKET capture is only supported on Linux")
+}
+
+// Stop is a no-op on non-Linux platforms.
+func (c *AFPacketCapture) Stop() {
+	// no-op on non-Linux platforms
+}
+
+// Offer is a no-op on non-Linux platforms.
+func (c *AFPacketCapture) Offer([]byte, bool) {
+	// no-op on non-Linux platforms
+}

util/capture/capture.go

@@ -0,0 +1,59 @@
+// Package capture provides userspace packet capture in pcap format.
+//
+// It taps decrypted WireGuard packets flowing through the FilteredDevice and
+// writes them as pcap (readable by tcpdump, tshark, Wireshark) or as
+// human-readable one-line-per-packet text.
+package capture
+
+import "io"
+
+// Direction indicates whether a packet is entering or leaving the host.
+type Direction uint8
+
+const (
+	// Inbound is a packet arriving from the network (FilteredDevice.Write path).
+	Inbound Direction = iota
+	// Outbound is a packet leaving the host (FilteredDevice.Read path).
+	Outbound
+)
+
+// String returns "IN" or "OUT".
+func (d Direction) String() string {
+	if d == Outbound {
+		return "OUT"
+	}
+	return "IN"
+}
+
+const (
+	protoICMP   = 1
+	protoTCP    = 6
+	protoUDP    = 17
+	protoICMPv6 = 58
+)
+
+// Options configures a capture session.
+type Options struct {
+	// Output receives pcap-formatted data. Nil disables pcap output.
+	Output io.Writer
+	// TextOutput receives human-readable packet summaries. Nil disables text output.
+	TextOutput io.Writer
+	// Matcher selects which packets to capture. Nil captures all.
+	// Use ParseFilter("host 10.0.0.1 and tcp") or &Filter{...}.
+	Matcher Matcher
+	// Verbose adds seq/ack, TTL, window, total length to text output.
+	Verbose bool
+	// ASCII dumps transport payload as printable ASCII after each packet line.
+	ASCII bool
+	// SnapLen is the maximum bytes captured per packet. 0 means 65535.
+	SnapLen uint32
+	// BufSize is the internal channel buffer size. 0 means 256.
+	BufSize int
+}
+
+// Stats reports capture session counters.
+type Stats struct {
+	Packets int64
+	Bytes   int64
+	Dropped int64
+}

util/capture/filter.go

@@ -0,0 +1,528 @@
+package capture
+
+import (
+	"encoding/binary"
+	"fmt"
+	"net/netip"
+	"strconv"
+	"strings"
+)
+
+// Matcher tests whether a raw packet should be captured.
+type Matcher interface {
+	Match(data []byte) bool
+}
+
+// Filter selects packets by flat AND'd criteria. Useful for structured APIs
+// (query params, proto fields). Implements Matcher.
+type Filter struct {
+	SrcIP   netip.Addr
+	DstIP   netip.Addr
+	Host    netip.Addr
+	SrcPort uint16
+	DstPort uint16
+	Port    uint16
+	Proto   uint8
+}
+
+// IsEmpty returns true if the filter has no criteria set.
+func (f *Filter) IsEmpty() bool {
+	return !f.SrcIP.IsValid() && !f.DstIP.IsValid() && !f.Host.IsValid() &&
+		f.SrcPort == 0 && f.DstPort == 0 && f.Port == 0 && f.Proto == 0
+}
+
+// Match implements Matcher. All non-zero fields must match (AND).
+func (f *Filter) Match(data []byte) bool {
+	if f.IsEmpty() {
+		return true
+	}
+	info, ok := parsePacketInfo(data)
+	if !ok {
+		return false
+	}
+	if f.Host.IsValid() && info.srcIP != f.Host && info.dstIP != f.Host {
+		return false
+	}
+	if f.SrcIP.IsValid() && info.srcIP != f.SrcIP {
+		return false
+	}
+	if f.DstIP.IsValid() && info.dstIP != f.DstIP {
+		return false
+	}
+	if f.Proto != 0 && info.proto != f.Proto {
+		return false
+	}
+	if f.Port != 0 && info.srcPort != f.Port && info.dstPort != f.Port {
+		return false
+	}
+	if f.SrcPort != 0 && info.srcPort != f.SrcPort {
+		return false
+	}
+	if f.DstPort != 0 && info.dstPort != f.DstPort {
+		return false
+	}
+	return true
+}
+
+// exprNode evaluates a filter condition against pre-parsed packet info.
+type exprNode func(info *packetInfo) bool
+
+// exprMatcher wraps an expression tree. Parses the packet once, then walks the tree.
+type exprMatcher struct {
+	root exprNode
+}
+
+func (m *exprMatcher) Match(data []byte) bool {
+	info, ok := parsePacketInfo(data)
+	if !ok {
+		return false
+	}
+	return m.root(&info)
+}
+
+func nodeAnd(a, b exprNode) exprNode {
+	return func(info *packetInfo) bool { return a(info) && b(info) }
+}
+
+func nodeOr(a, b exprNode) exprNode {
+	return func(info *packetInfo) bool { return a(info) || b(info) }
+}
+
+func nodeNot(n exprNode) exprNode {
+	return func(info *packetInfo) bool { return !n(info) }
+}
+
+func nodeHost(addr netip.Addr) exprNode {
+	return func(info *packetInfo) bool { return info.srcIP == addr || info.dstIP == addr }
+}
+
+func nodeSrcHost(addr netip.Addr) exprNode {
+	return func(info *packetInfo) bool { return info.srcIP == addr }
+}
+
+func nodeDstHost(addr netip.Addr) exprNode {
+	return func(info *packetInfo) bool { return info.dstIP == addr }
+}
+
+func nodePort(port uint16) exprNode {
+	return func(info *packetInfo) bool { return info.srcPort == port || info.dstPort == port }
+}
+
+func nodeSrcPort(port uint16) exprNode {
+	return func(info *packetInfo) bool { return info.srcPort == port }
+}
+
+func nodeDstPort(port uint16) exprNode {
+	return func(info *packetInfo) bool { return info.dstPort == port }
+}
+
+func nodeProto(proto uint8) exprNode {
+	return func(info *packetInfo) bool { return info.proto == proto }
+}
+
+func nodeFamily(family uint8) exprNode {
+	return func(info *packetInfo) bool { return info.family == family }
+}
+
+func nodeNet(prefix netip.Prefix) exprNode {
+	return func(info *packetInfo) bool { return prefix.Contains(info.srcIP) || prefix.Contains(info.dstIP) }
+}
+
+func nodeSrcNet(prefix netip.Prefix) exprNode {
+	return func(info *packetInfo) bool { return prefix.Contains(info.srcIP) }
+}
+
+func nodeDstNet(prefix netip.Prefix) exprNode {
+	return func(info *packetInfo) bool { return prefix.Contains(info.dstIP) }
+}
+
+// packetInfo holds parsed header fields for filtering and display.
+type packetInfo struct {
+	family  uint8
+	srcIP   netip.Addr
+	dstIP   netip.Addr
+	proto   uint8
+	srcPort uint16
+	dstPort uint16
+	hdrLen  int
+}
+
+func parsePacketInfo(data []byte) (packetInfo, bool) {
+	if len(data) < 1 {
+		return packetInfo{}, false
+	}
+	switch data[0] >> 4 {
+	case 4:
+		return parseIPv4Info(data)
+	case 6:
+		return parseIPv6Info(data)
+	default:
+		return packetInfo{}, false
+	}
+}
+
+func parseIPv4Info(data []byte) (packetInfo, bool) {
+	if len(data) < 20 {
+		return packetInfo{}, false
+	}
+	ihl := int(data[0]&0x0f) * 4
+	if ihl < 20 || len(data) < ihl {
+		return packetInfo{}, false
+	}
+	info := packetInfo{
+		family: 4,
+		srcIP:  netip.AddrFrom4([4]byte{data[12], data[13], data[14], data[15]}),
+		dstIP:  netip.AddrFrom4([4]byte{data[16], data[17], data[18], data[19]}),
+		proto:  data[9],
+		hdrLen: ihl,
+	}
+	if (info.proto == protoTCP || info.proto == protoUDP) && len(data) >= ihl+4 {
+		info.srcPort = binary.BigEndian.Uint16(data[ihl:])
+		info.dstPort = binary.BigEndian.Uint16(data[ihl+2:])
+	}
+	return info, true
+}
+
+// parseIPv6Info parses the fixed IPv6 header. It reads the Next Header field
+// directly, so packets with extension headers (hop-by-hop, routing, fragment,
+// etc.) will report the extension type as the protocol rather than the final
+// transport protocol. This is acceptable for a debug capture tool.
+func parseIPv6Info(data []byte) (packetInfo, bool) {
+	if len(data) < 40 {
+		return packetInfo{}, false
+	}
+	var src, dst [16]byte
+	copy(src[:], data[8:24])
+	copy(dst[:], data[24:40])
+	info := packetInfo{
+		family: 6,
+		srcIP:  netip.AddrFrom16(src),
+		dstIP:  netip.AddrFrom16(dst),
+		proto:  data[6],
+		hdrLen: 40,
+	}
+	if (info.proto == protoTCP || info.proto == protoUDP) && len(data) >= 44 {
+		info.srcPort = binary.BigEndian.Uint16(data[40:])
+		info.dstPort = binary.BigEndian.Uint16(data[42:])
+	}
+	return info, true
+}
+
+// ParseFilter parses a BPF-like filter expression and returns a Matcher.
+// Returns nil Matcher for an empty expression (match all).
+//
+// Grammar (mirrors common tcpdump BPF syntax):
+//
+//	orExpr   = andExpr ("or" andExpr)*
+//	andExpr  = unary ("and" unary)*
+//	unary    = "not" unary | "(" orExpr ")" | term
+//
+//	term     = "host" IP | "src" target | "dst" target
+//	         | "port" NUM | "net" PREFIX
+//	         | "tcp" | "udp" | "icmp" | "icmp6"
+//	         | "ip" | "ip6" | "proto" NUM
+//	target   = "host" IP | "port" NUM | "net" PREFIX | IP
+//
+// Examples:
+//
+//	host 10.0.0.1 and tcp port 443
+//	not port 22
+//	(host 10.0.0.1 or host 10.0.0.2) and tcp
+//	ip6 and icmp6
+//	net 10.0.0.0/24
+//	src host 10.0.0.1 or dst port 80
+func ParseFilter(expr string) (Matcher, error) {
+	tokens := tokenize(expr)
+	if len(tokens) == 0 {
+		return nil, nil //nolint:nilnil // nil Matcher means "match all"
+	}
+
+	p := &parser{tokens: tokens}
+	node, err := p.parseOr()
+	if err != nil {
+		return nil, err
+	}
+	if p.pos < len(p.tokens) {
+		return nil, fmt.Errorf("unexpected token %q at position %d", p.tokens[p.pos], p.pos)
+	}
+	return &exprMatcher{root: node}, nil
+}
+
+func tokenize(expr string) []string {
+	expr = strings.TrimSpace(expr)
+	if expr == "" {
+		return nil
+	}
+	// Split on whitespace but keep parens as separate tokens.
+	var tokens []string
+	for _, field := range strings.Fields(expr) {
+		tokens = append(tokens, splitParens(field)...)
+	}
+	return tokens
+}
+
+// splitParens splits "(foo)" into "(", "foo", ")".
+func splitParens(s string) []string {
+	var out []string
+	for strings.HasPrefix(s, "(") {
+		out = append(out, "(")
+		s = s[1:]
+	}
+	var trail []string
+	for strings.HasSuffix(s, ")") {
+		trail = append(trail, ")")
+		s = s[:len(s)-1]
+	}
+	if s != "" {
+		out = append(out, s)
+	}
+	out = append(out, trail...)
+	return out
+}
+
+type parser struct {
+	tokens []string
+	pos    int
+}
+
+func (p *parser) peek() string {
+	if p.pos >= len(p.tokens) {
+		return ""
+	}
+	return strings.ToLower(p.tokens[p.pos])
+}
+
+func (p *parser) next() string {
+	tok := p.peek()
+	if tok != "" {
+		p.pos++
+	}
+	return tok
+}
+
+func (p *parser) expect(tok string) error {
+	got := p.next()
+	if got != tok {
+		return fmt.Errorf("expected %q, got %q", tok, got)
+	}
+	return nil
+}
+
+func (p *parser) parseOr() (exprNode, error) {
+	left, err := p.parseAnd()
+	if err != nil {
+		return nil, err
+	}
+	for p.peek() == "or" {
+		p.next()
+		right, err := p.parseAnd()
+		if err != nil {
+			return nil, err
+		}
+		left = nodeOr(left, right)
+	}
+	return left, nil
+}
+
+func (p *parser) parseAnd() (exprNode, error) {
+	left, err := p.parseUnary()
+	if err != nil {
+		return nil, err
+	}
+	for {
+		tok := p.peek()
+		if tok == "and" {
+			p.next()
+			right, err := p.parseUnary()
+			if err != nil {
+				return nil, err
+			}
+			left = nodeAnd(left, right)
+			continue
+		}
+		// Implicit AND: two atoms without "and" between them.
+		// Only if the next token starts an atom (not "or", ")", or EOF).
+		if tok != "" && tok != "or" && tok != ")" {
+			right, err := p.parseUnary()
+			if err != nil {
+				return nil, err
+			}
+			left = nodeAnd(left, right)
+			continue
+		}
+		break
+	}
+	return left, nil
+}
+
+func (p *parser) parseUnary() (exprNode, error) {
+	switch p.peek() {
+	case "not":
+		p.next()
+		inner, err := p.parseUnary()
+		if err != nil {
+			return nil, err
+		}
+		return nodeNot(inner), nil
+	case "(":
+		p.next()
+		inner, err := p.parseOr()
+		if err != nil {
+			return nil, err
+		}
+		if err := p.expect(")"); err != nil {
+			return nil, fmt.Errorf("unclosed parenthesis")
+		}
+		return inner, nil
+	default:
+		return p.parseAtom()
+	}
+}
+
+func (p *parser) parseAtom() (exprNode, error) {
+	tok := p.next()
+	if tok == "" {
+		return nil, fmt.Errorf("unexpected end of expression")
+	}
+
+	switch tok {
+	case "host":
+		addr, err := p.parseAddr()
+		if err != nil {
+			return nil, fmt.Errorf("host: %w", err)
+		}
+		return nodeHost(addr), nil
+
+	case "port":
+		port, err := p.parsePort()
+		if err != nil {
+			return nil, fmt.Errorf("port: %w", err)
+		}
+		return nodePort(port), nil
+
+	case "net":
+		prefix, err := p.parsePrefix()
+		if err != nil {
+			return nil, fmt.Errorf("net: %w", err)
+		}
+		return nodeNet(prefix), nil
+
+	case "src":
+		return p.parseDirTarget(true)
+
+	case "dst":
+		return p.parseDirTarget(false)
+
+	case "tcp":
+		return nodeProto(protoTCP), nil
+	case "udp":
+		return nodeProto(protoUDP), nil
+	case "icmp":
+		return nodeProto(protoICMP), nil
+	case "icmp6":
+		return nodeProto(protoICMPv6), nil
+	case "ip":
+		return nodeFamily(4), nil
+	case "ip6":
+		return nodeFamily(6), nil
+
+	case "proto":
+		raw := p.next()
+		if raw == "" {
+			return nil, fmt.Errorf("proto: missing number")
+		}
+		n, err := strconv.Atoi(raw)
+		if err != nil || n < 0 || n > 255 {
+			return nil, fmt.Errorf("proto: invalid number %q", raw)
+		}
+		return nodeProto(uint8(n)), nil
+
+	default:
+		return nil, fmt.Errorf("unknown filter keyword %q", tok)
+	}
+}
+
+func (p *parser) parseDirTarget(isSrc bool) (exprNode, error) {
+	tok := p.peek()
+	switch tok {
+	case "host":
+		p.next()
+		addr, err := p.parseAddr()
+		if err != nil {
+			return nil, err
+		}
+		if isSrc {
+			return nodeSrcHost(addr), nil
+		}
+		return nodeDstHost(addr), nil
+
+	case "port":
+		p.next()
+		port, err := p.parsePort()
+		if err != nil {
+			return nil, err
+		}
+		if isSrc {
+			return nodeSrcPort(port), nil
+		}
+		return nodeDstPort(port), nil
+
+	case "net":
+		p.next()
+		prefix, err := p.parsePrefix()
+		if err != nil {
+			return nil, err
+		}
+		if isSrc {
+			return nodeSrcNet(prefix), nil
+		}
+		return nodeDstNet(prefix), nil
+
+	default:
+		// Try as bare IP: "src 10.0.0.1"
+		addr, err := p.parseAddr()
+		if err != nil {
+			return nil, fmt.Errorf("expected host, port, net, or IP after src/dst, got %q", tok)
+		}
+		if isSrc {
+			return nodeSrcHost(addr), nil
+		}
+		return nodeDstHost(addr), nil
+	}
+}
+
+func (p *parser) parseAddr() (netip.Addr, error) {
+	raw := p.next()
+	if raw == "" {
+		return netip.Addr{}, fmt.Errorf("missing IP address")
+	}
+	addr, err := netip.ParseAddr(raw)
+	if err != nil {
+		return netip.Addr{}, fmt.Errorf("invalid IP %q", raw)
+	}
+	return addr.Unmap(), nil
+}
+
+func (p *parser) parsePort() (uint16, error) {
+	raw := p.next()
+	if raw == "" {
+		return 0, fmt.Errorf("missing port number")
+	}
+	n, err := strconv.Atoi(raw)
+	if err != nil || n < 1 || n > 65535 {
+		return 0, fmt.Errorf("invalid port %q", raw)
+	}
+	return uint16(n), nil
+}
+
+func (p *parser) parsePrefix() (netip.Prefix, error) {
+	raw := p.next()
+	if raw == "" {
+		return netip.Prefix{}, fmt.Errorf("missing network prefix")
+	}
+	prefix, err := netip.ParsePrefix(raw)
+	if err != nil {
+		return netip.Prefix{}, fmt.Errorf("invalid prefix %q", raw)
+	}
+	return prefix, nil
+}

util/capture/filter_test.go

@@ -0,0 +1,263 @@
+package capture
+
+import (
+	"net/netip"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+// buildIPv4Packet creates a minimal IPv4+TCP/UDP packet for filter testing.
+func buildIPv4Packet(t *testing.T, srcIP, dstIP netip.Addr, proto uint8, srcPort, dstPort uint16) []byte {
+	t.Helper()
+
+	hdrLen := 20
+	pkt := make([]byte, hdrLen+20)
+	pkt[0] = 0x45
+	pkt[9] = proto
+
+	src := srcIP.As4()
+	dst := dstIP.As4()
+	copy(pkt[12:16], src[:])
+	copy(pkt[16:20], dst[:])
+
+	pkt[20] = byte(srcPort >> 8)
+	pkt[21] = byte(srcPort)
+	pkt[22] = byte(dstPort >> 8)
+	pkt[23] = byte(dstPort)
+
+	return pkt
+}
+
+// buildIPv6Packet creates a minimal IPv6+TCP/UDP packet for filter testing.
+func buildIPv6Packet(t *testing.T, srcIP, dstIP netip.Addr, proto uint8, srcPort, dstPort uint16) []byte {
+	t.Helper()
+
+	pkt := make([]byte, 44) // 40 header + 4 ports
+	pkt[0] = 0x60           // version 6
+	pkt[6] = proto          // next header
+
+	src := srcIP.As16()
+	dst := dstIP.As16()
+	copy(pkt[8:24], src[:])
+	copy(pkt[24:40], dst[:])
+
+	pkt[40] = byte(srcPort >> 8)
+	pkt[41] = byte(srcPort)
+	pkt[42] = byte(dstPort >> 8)
+	pkt[43] = byte(dstPort)
+
+	return pkt
+}
+
+// ---- Filter struct tests ----
+
+func TestFilter_Empty(t *testing.T) {
+	f := Filter{}
+	assert.True(t, f.IsEmpty())
+	assert.True(t, f.Match(buildIPv4Packet(t,
+		netip.MustParseAddr("10.0.0.1"),
+		netip.MustParseAddr("10.0.0.2"),
+		protoTCP, 12345, 443)))
+}
+
+func TestFilter_Host(t *testing.T) {
+	f := Filter{Host: netip.MustParseAddr("10.0.0.1")}
+	assert.True(t, f.Match(buildIPv4Packet(t, netip.MustParseAddr("10.0.0.1"), netip.MustParseAddr("10.0.0.2"), protoTCP, 1234, 80)))
+	assert.True(t, f.Match(buildIPv4Packet(t, netip.MustParseAddr("10.0.0.2"), netip.MustParseAddr("10.0.0.1"), protoTCP, 1234, 80)))
+	assert.False(t, f.Match(buildIPv4Packet(t, netip.MustParseAddr("10.0.0.2"), netip.MustParseAddr("10.0.0.3"), protoTCP, 1234, 80)))
+}
+
+func TestFilter_InvalidPacket(t *testing.T) {
+	f := Filter{Host: netip.MustParseAddr("10.0.0.1")}
+	assert.False(t, f.Match(nil))
+	assert.False(t, f.Match([]byte{}))
+	assert.False(t, f.Match([]byte{0x00}))
+}
+
+func TestParsePacketInfo_IPv4(t *testing.T) {
+	pkt := buildIPv4Packet(t, netip.MustParseAddr("192.168.1.1"), netip.MustParseAddr("10.0.0.1"), protoTCP, 54321, 80)
+	info, ok := parsePacketInfo(pkt)
+	require.True(t, ok)
+	assert.Equal(t, uint8(4), info.family)
+	assert.Equal(t, netip.MustParseAddr("192.168.1.1"), info.srcIP)
+	assert.Equal(t, netip.MustParseAddr("10.0.0.1"), info.dstIP)
+	assert.Equal(t, uint8(protoTCP), info.proto)
+	assert.Equal(t, uint16(54321), info.srcPort)
+	assert.Equal(t, uint16(80), info.dstPort)
+}
+
+func TestParsePacketInfo_IPv6(t *testing.T) {
+	pkt := buildIPv6Packet(t, netip.MustParseAddr("fd00::1"), netip.MustParseAddr("fd00::2"), protoUDP, 1234, 53)
+	info, ok := parsePacketInfo(pkt)
+	require.True(t, ok)
+	assert.Equal(t, uint8(6), info.family)
+	assert.Equal(t, netip.MustParseAddr("fd00::1"), info.srcIP)
+	assert.Equal(t, netip.MustParseAddr("fd00::2"), info.dstIP)
+	assert.Equal(t, uint8(protoUDP), info.proto)
+	assert.Equal(t, uint16(1234), info.srcPort)
+	assert.Equal(t, uint16(53), info.dstPort)
+}
+
+// ---- ParseFilter expression tests ----
+
+func matchV4(t *testing.T, m Matcher, srcIP, dstIP string, proto uint8, srcPort, dstPort uint16) bool {
+	t.Helper()
+	return m.Match(buildIPv4Packet(t, netip.MustParseAddr(srcIP), netip.MustParseAddr(dstIP), proto, srcPort, dstPort))
+}
+
+func matchV6(t *testing.T, m Matcher, srcIP, dstIP string, proto uint8, srcPort, dstPort uint16) bool {
+	t.Helper()
+	return m.Match(buildIPv6Packet(t, netip.MustParseAddr(srcIP), netip.MustParseAddr(dstIP), proto, srcPort, dstPort))
+}
+
+func TestParseFilter_Empty(t *testing.T) {
+	m, err := ParseFilter("")
+	require.NoError(t, err)
+	assert.Nil(t, m, "empty expression should return nil matcher")
+}
+
+func TestParseFilter_Atoms(t *testing.T) {
+	tests := []struct {
+		expr  string
+		match bool
+	}{
+		{"tcp", true},
+		{"udp", false},
+		{"host 10.0.0.1", true},
+		{"host 10.0.0.99", false},
+		{"port 443", true},
+		{"port 80", false},
+		{"src host 10.0.0.1", true},
+		{"dst host 10.0.0.2", true},
+		{"dst host 10.0.0.1", false},
+		{"src port 12345", true},
+		{"dst port 443", true},
+		{"dst port 80", false},
+		{"proto 6", true},
+		{"proto 17", false},
+	}
+
+	pkt := buildIPv4Packet(t, netip.MustParseAddr("10.0.0.1"), netip.MustParseAddr("10.0.0.2"), protoTCP, 12345, 443)
+
+	for _, tt := range tests {
+		t.Run(tt.expr, func(t *testing.T) {
+			m, err := ParseFilter(tt.expr)
+			require.NoError(t, err)
+			assert.Equal(t, tt.match, m.Match(pkt))
+		})
+	}
+}
+
+func TestParseFilter_And(t *testing.T) {
+	m, err := ParseFilter("host 10.0.0.1 and tcp port 443")
+	require.NoError(t, err)
+	assert.True(t, matchV4(t, m, "10.0.0.1", "10.0.0.2", protoTCP, 55555, 443))
+	assert.False(t, matchV4(t, m, "10.0.0.1", "10.0.0.2", protoUDP, 55555, 443), "wrong proto")
+	assert.False(t, matchV4(t, m, "10.0.0.3", "10.0.0.2", protoTCP, 55555, 443), "wrong host")
+	assert.False(t, matchV4(t, m, "10.0.0.1", "10.0.0.2", protoTCP, 55555, 80), "wrong port")
+}
+
+func TestParseFilter_ImplicitAnd(t *testing.T) {
+	// "tcp port 443" = implicit AND between tcp and port 443
+	m, err := ParseFilter("tcp port 443")
+	require.NoError(t, err)
+	assert.True(t, matchV4(t, m, "10.0.0.1", "10.0.0.2", protoTCP, 1, 443))
+	assert.False(t, matchV4(t, m, "10.0.0.1", "10.0.0.2", protoUDP, 1, 443))
+}
+
+func TestParseFilter_Or(t *testing.T) {
+	m, err := ParseFilter("port 80 or port 443")
+	require.NoError(t, err)
+	assert.True(t, matchV4(t, m, "1.2.3.4", "5.6.7.8", protoTCP, 1, 80))
+	assert.True(t, matchV4(t, m, "1.2.3.4", "5.6.7.8", protoTCP, 1, 443))
+	assert.False(t, matchV4(t, m, "1.2.3.4", "5.6.7.8", protoTCP, 1, 8080))
+}
+
+func TestParseFilter_Not(t *testing.T) {
+	m, err := ParseFilter("not port 22")
+	require.NoError(t, err)
+	assert.True(t, matchV4(t, m, "10.0.0.1", "10.0.0.2", protoTCP, 1, 443))
+	assert.False(t, matchV4(t, m, "10.0.0.1", "10.0.0.2", protoTCP, 1, 22))
+	assert.False(t, matchV4(t, m, "10.0.0.1", "10.0.0.2", protoTCP, 22, 80))
+}
+
+func TestParseFilter_Parens(t *testing.T) {
+	m, err := ParseFilter("(port 80 or port 443) and tcp")
+	require.NoError(t, err)
+	assert.True(t, matchV4(t, m, "1.2.3.4", "5.6.7.8", protoTCP, 1, 443))
+	assert.False(t, matchV4(t, m, "1.2.3.4", "5.6.7.8", protoUDP, 1, 443), "wrong proto")
+	assert.False(t, matchV4(t, m, "1.2.3.4", "5.6.7.8", protoTCP, 1, 8080), "wrong port")
+}
+
+func TestParseFilter_Family(t *testing.T) {
+	mV4, err := ParseFilter("ip")
+	require.NoError(t, err)
+	assert.True(t, matchV4(t, mV4, "10.0.0.1", "10.0.0.2", protoTCP, 1, 80))
+	assert.False(t, matchV6(t, mV4, "fd00::1", "fd00::2", protoTCP, 1, 80))
+
+	mV6, err := ParseFilter("ip6")
+	require.NoError(t, err)
+	assert.False(t, matchV4(t, mV6, "10.0.0.1", "10.0.0.2", protoTCP, 1, 80))
+	assert.True(t, matchV6(t, mV6, "fd00::1", "fd00::2", protoTCP, 1, 80))
+}
+
+func TestParseFilter_Net(t *testing.T) {
+	m, err := ParseFilter("net 10.0.0.0/24")
+	require.NoError(t, err)
+	assert.True(t, matchV4(t, m, "10.0.0.1", "192.168.1.1", protoTCP, 1, 80), "src in net")
+	assert.True(t, matchV4(t, m, "192.168.1.1", "10.0.0.200", protoTCP, 1, 80), "dst in net")
+	assert.False(t, matchV4(t, m, "10.0.1.1", "192.168.1.1", protoTCP, 1, 80), "neither in net")
+}
+
+func TestParseFilter_SrcDstNet(t *testing.T) {
+	m, err := ParseFilter("src net 10.0.0.0/8 and dst net 192.168.0.0/16")
+	require.NoError(t, err)
+	assert.True(t, matchV4(t, m, "10.1.2.3", "192.168.1.1", protoTCP, 1, 80))
+	assert.False(t, matchV4(t, m, "192.168.1.1", "10.1.2.3", protoTCP, 1, 80), "reversed")
+}
+
+func TestParseFilter_Complex(t *testing.T) {
+	// Real-world: capture HTTP(S) traffic to/from specific host, excluding SSH
+	m, err := ParseFilter("host 10.0.0.1 and (port 80 or port 443) and not port 22")
+	require.NoError(t, err)
+	assert.True(t, matchV4(t, m, "10.0.0.1", "10.0.0.2", protoTCP, 55555, 443))
+	assert.True(t, matchV4(t, m, "10.0.0.2", "10.0.0.1", protoTCP, 55555, 80))
+	assert.False(t, matchV4(t, m, "10.0.0.1", "10.0.0.2", protoTCP, 22, 443), "port 22 excluded")
+	assert.False(t, matchV4(t, m, "10.0.0.3", "10.0.0.2", protoTCP, 55555, 443), "wrong host")
+}
+
+func TestParseFilter_IPv6Combined(t *testing.T) {
+	m, err := ParseFilter("ip6 and icmp6")
+	require.NoError(t, err)
+	assert.True(t, matchV6(t, m, "fd00::1", "fd00::2", protoICMPv6, 0, 0))
+	assert.False(t, matchV4(t, m, "10.0.0.1", "10.0.0.2", protoICMP, 0, 0), "wrong family")
+	assert.False(t, matchV6(t, m, "fd00::1", "fd00::2", protoTCP, 1, 80), "wrong proto")
+}
+
+func TestParseFilter_CaseInsensitive(t *testing.T) {
+	m, err := ParseFilter("HOST 10.0.0.1 AND TCP PORT 443")
+	require.NoError(t, err)
+	assert.True(t, matchV4(t, m, "10.0.0.1", "10.0.0.2", protoTCP, 1, 443))
+}
+
+func TestParseFilter_Errors(t *testing.T) {
+	bad := []string{
+		"badkeyword",
+		"host",
+		"port abc",
+		"port 99999",
+		"net invalid",
+		"(",
+		"(port 80",
+		"not",
+		"src",
+	}
+	for _, expr := range bad {
+		t.Run(expr, func(t *testing.T) {
+			_, err := ParseFilter(expr)
+			assert.Error(t, err, "should fail for %q", expr)
+		})
+	}
+}

util/capture/pcap.go

@@ -0,0 +1,85 @@
+package capture
+
+import (
+	"encoding/binary"
+	"io"
+	"time"
+)
+
+const (
+	pcapMagic      = 0xa1b2c3d4
+	pcapVersionMaj = 2
+	pcapVersionMin = 4
+	// linkTypeRaw is LINKTYPE_RAW: raw IPv4/IPv6 packets without link-layer header.
+	linkTypeRaw    = 101
+	defaultSnapLen = 65535
+)
+
+// PcapWriter writes packets in pcap format to an underlying writer.
+// The global header is written lazily on the first WritePacket call so that
+// the writer can be used with unbuffered io.Pipes without deadlocking.
+// It is not safe for concurrent use; callers must serialize access.
+type PcapWriter struct {
+	w             io.Writer
+	snapLen       uint32
+	headerWritten bool
+}
+
+// NewPcapWriter creates a pcap writer. The global header is deferred until the
+// first WritePacket call.
+func NewPcapWriter(w io.Writer, snapLen uint32) *PcapWriter {
+	if snapLen == 0 {
+		snapLen = defaultSnapLen
+	}
+	return &PcapWriter{w: w, snapLen: snapLen}
+}
+
+// writeGlobalHeader writes the 24-byte pcap file header.
+func (pw *PcapWriter) writeGlobalHeader() error {
+	var hdr [24]byte
+	binary.LittleEndian.PutUint32(hdr[0:4], pcapMagic)
+	binary.LittleEndian.PutUint16(hdr[4:6], pcapVersionMaj)
+	binary.LittleEndian.PutUint16(hdr[6:8], pcapVersionMin)
+	binary.LittleEndian.PutUint32(hdr[16:20], pw.snapLen)
+	binary.LittleEndian.PutUint32(hdr[20:24], linkTypeRaw)
+
+	_, err := pw.w.Write(hdr[:])
+	return err
+}
+
+// WriteHeader writes the pcap global header. Safe to call multiple times.
+func (pw *PcapWriter) WriteHeader() error {
+	if pw.headerWritten {
+		return nil
+	}
+	if err := pw.writeGlobalHeader(); err != nil {
+		return err
+	}
+	pw.headerWritten = true
+	return nil
+}
+
+// WritePacket writes a single packet record, preceded by the global header
+// on the first call.
+func (pw *PcapWriter) WritePacket(ts time.Time, data []byte) error {
+	if err := pw.WriteHeader(); err != nil {
+		return err
+	}
+
+	origLen := uint32(len(data))
+	if origLen > pw.snapLen {
+		data = data[:pw.snapLen]
+	}
+
+	var hdr [16]byte
+	binary.LittleEndian.PutUint32(hdr[0:4], uint32(ts.Unix()))
+	binary.LittleEndian.PutUint32(hdr[4:8], uint32(ts.Nanosecond()/1000))
+	binary.LittleEndian.PutUint32(hdr[8:12], uint32(len(data)))
+	binary.LittleEndian.PutUint32(hdr[12:16], origLen)
+
+	if _, err := pw.w.Write(hdr[:]); err != nil {
+		return err
+	}
+	_, err := pw.w.Write(data)
+	return err
+}

util/capture/pcap_test.go

@@ -0,0 +1,68 @@
+package capture
+
+import (
+	"bytes"
+	"encoding/binary"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestPcapWriter_GlobalHeader(t *testing.T) {
+	var buf bytes.Buffer
+	pw := NewPcapWriter(&buf, 0)
+
+	// Header is lazy, so write a dummy packet to trigger it.
+	err := pw.WritePacket(time.Now(), []byte{0x45, 0, 0, 20, 0, 0, 0, 0, 64, 1, 0, 0, 10, 0, 0, 1, 10, 0, 0, 2})
+	require.NoError(t, err)
+
+	data := buf.Bytes()
+	require.GreaterOrEqual(t, len(data), 24, "should contain global header")
+
+	assert.Equal(t, uint32(pcapMagic), binary.LittleEndian.Uint32(data[0:4]), "magic number")
+	assert.Equal(t, uint16(pcapVersionMaj), binary.LittleEndian.Uint16(data[4:6]), "version major")
+	assert.Equal(t, uint16(pcapVersionMin), binary.LittleEndian.Uint16(data[6:8]), "version minor")
+	assert.Equal(t, uint32(defaultSnapLen), binary.LittleEndian.Uint32(data[16:20]), "snap length")
+	assert.Equal(t, uint32(linkTypeRaw), binary.LittleEndian.Uint32(data[20:24]), "link type")
+}
+
+func TestPcapWriter_WritePacket(t *testing.T) {
+	var buf bytes.Buffer
+	pw := NewPcapWriter(&buf, 100)
+
+	ts := time.Date(2025, 6, 15, 12, 30, 45, 123456000, time.UTC)
+	payload := make([]byte, 50)
+	for i := range payload {
+		payload[i] = byte(i)
+	}
+
+	err := pw.WritePacket(ts, payload)
+	require.NoError(t, err)
+
+	data := buf.Bytes()[24:] // skip global header
+	require.Len(t, data, 16+50, "packet header + payload")
+
+	assert.Equal(t, uint32(ts.Unix()), binary.LittleEndian.Uint32(data[0:4]), "timestamp seconds")
+	assert.Equal(t, uint32(123456), binary.LittleEndian.Uint32(data[4:8]), "timestamp microseconds")
+	assert.Equal(t, uint32(50), binary.LittleEndian.Uint32(data[8:12]), "included length")
+	assert.Equal(t, uint32(50), binary.LittleEndian.Uint32(data[12:16]), "original length")
+	assert.Equal(t, payload, data[16:], "packet data")
+}
+
+func TestPcapWriter_SnapLen(t *testing.T) {
+	var buf bytes.Buffer
+	pw := NewPcapWriter(&buf, 10)
+
+	ts := time.Now()
+	payload := make([]byte, 50)
+
+	err := pw.WritePacket(ts, payload)
+	require.NoError(t, err)
+
+	data := buf.Bytes()[24:]
+	assert.Equal(t, uint32(10), binary.LittleEndian.Uint32(data[8:12]), "included length should be truncated")
+	assert.Equal(t, uint32(50), binary.LittleEndian.Uint32(data[12:16]), "original length preserved")
+	assert.Len(t, data[16:], 10, "only snap_len bytes written")
+}

util/capture/session.go

@@ -0,0 +1,213 @@
+package capture
+
+import (
+	"fmt"
+	"sync"
+	"sync/atomic"
+	"time"
+)
+
+const defaultBufSize = 256
+
+type packetEntry struct {
+	ts   time.Time
+	data []byte
+	dir  Direction
+}
+
+// Session manages an active packet capture. Packets are offered via Offer,
+// buffered in a channel, and written to configured sinks by a background
+// goroutine. This keeps the hot path (FilteredDevice.Read/Write) non-blocking.
+//
+// The caller must call Stop when done to flush remaining packets and release
+// resources.
+type Session struct {
+	pcapW   *PcapWriter
+	textW   *TextWriter
+	matcher Matcher
+	snapLen uint32
+	flushFn func()
+
+	ch      chan packetEntry
+	done    chan struct{}
+	stopped chan struct{}
+
+	closeOnce sync.Once
+	closed    atomic.Bool
+	packets   atomic.Int64
+	bytes     atomic.Int64
+	dropped   atomic.Int64
+	started   time.Time
+}
+
+// NewSession creates and starts a capture session. At least one of
+// Options.Output or Options.TextOutput must be non-nil.
+func NewSession(opts Options) (*Session, error) {
+	if opts.Output == nil && opts.TextOutput == nil {
+		return nil, fmt.Errorf("at least one output sink required")
+	}
+
+	snapLen := opts.SnapLen
+	if snapLen == 0 {
+		snapLen = defaultSnapLen
+	}
+
+	bufSize := opts.BufSize
+	if bufSize <= 0 {
+		bufSize = defaultBufSize
+	}
+
+	s := &Session{
+		matcher: opts.Matcher,
+		snapLen: snapLen,
+		ch:      make(chan packetEntry, bufSize),
+		done:    make(chan struct{}),
+		stopped: make(chan struct{}),
+		started: time.Now(),
+	}
+
+	if opts.Output != nil {
+		s.pcapW = NewPcapWriter(opts.Output, snapLen)
+	}
+	if opts.TextOutput != nil {
+		s.textW = NewTextWriter(opts.TextOutput, opts.Verbose, opts.ASCII)
+	}
+
+	s.flushFn = buildFlushFn(opts.Output, opts.TextOutput)
+
+	go s.run()
+	return s, nil
+}
+
+// Offer submits a packet for capture. It returns immediately and never blocks
+// the caller. If the internal buffer is full the packet is dropped silently.
+//
+// outbound should be true for packets leaving the host (FilteredDevice.Read
+// path) and false for packets arriving (FilteredDevice.Write path).
+//
+// Offer satisfies the device.PacketCapture interface.
+func (s *Session) Offer(data []byte, outbound bool) {
+	if s.closed.Load() {
+		return
+	}
+
+	if s.matcher != nil && !s.matcher.Match(data) {
+		return
+	}
+
+	captureLen := len(data)
+	if s.snapLen > 0 && uint32(captureLen) > s.snapLen {
+		captureLen = int(s.snapLen)
+	}
+
+	copied := make([]byte, captureLen)
+	copy(copied, data)
+
+	dir := Inbound
+	if outbound {
+		dir = Outbound
+	}
+
+	select {
+	case s.ch <- packetEntry{ts: time.Now(), data: copied, dir: dir}:
+		s.packets.Add(1)
+		s.bytes.Add(int64(len(data)))
+	default:
+		s.dropped.Add(1)
+	}
+}
+
+// Stop signals the session to stop accepting packets, drains any buffered
+// packets to the sinks, and waits for the writer goroutine to exit.
+// It is safe to call multiple times.
+func (s *Session) Stop() {
+	s.closeOnce.Do(func() {
+		s.closed.Store(true)
+		close(s.done)
+	})
+	<-s.stopped
+}
+
+// Done returns a channel that is closed when the session's writer goroutine
+// has fully exited and all buffered packets have been flushed.
+func (s *Session) Done() <-chan struct{} {
+	return s.stopped
+}
+
+// Stats returns current capture counters.
+func (s *Session) Stats() Stats {
+	return Stats{
+		Packets: s.packets.Load(),
+		Bytes:   s.bytes.Load(),
+		Dropped: s.dropped.Load(),
+	}
+}
+
+func (s *Session) run() {
+	defer close(s.stopped)
+
+	for {
+		select {
+		case pkt := <-s.ch:
+			s.write(pkt)
+		case <-s.done:
+			s.drain()
+			return
+		}
+	}
+}
+
+func (s *Session) drain() {
+	for {
+		select {
+		case pkt := <-s.ch:
+			s.write(pkt)
+		default:
+			return
+		}
+	}
+}
+
+func (s *Session) write(pkt packetEntry) {
+	if s.pcapW != nil {
+		// Best-effort: if the writer fails (broken pipe etc.), discard silently.
+		_ = s.pcapW.WritePacket(pkt.ts, pkt.data)
+	}
+	if s.textW != nil {
+		_ = s.textW.WritePacket(pkt.ts, pkt.data, pkt.dir)
+	}
+	s.flushFn()
+}
+
+// buildFlushFn returns a function that flushes all writers that support it.
+// This covers http.Flusher and similar streaming writers.
+func buildFlushFn(writers ...any) func() {
+	type flusher interface {
+		Flush()
+	}
+
+	var fns []func()
+	for _, w := range writers {
+		if w == nil {
+			continue
+		}
+		if f, ok := w.(flusher); ok {
+			fns = append(fns, f.Flush)
+		}
+	}
+
+	switch len(fns) {
+	case 0:
+		return func() {
+			// no writers to flush
+		}
+	case 1:
+		return fns[0]
+	default:
+		return func() {
+			for _, fn := range fns {
+				fn()
+			}
+		}
+	}
+}

util/capture/session_test.go

@@ -0,0 +1,144 @@
+package capture
+
+import (
+	"bytes"
+	"encoding/binary"
+	"net/netip"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestSession_PcapOutput(t *testing.T) {
+	var buf bytes.Buffer
+	sess, err := NewSession(Options{
+		Output:  &buf,
+		BufSize: 16,
+	})
+	require.NoError(t, err)
+
+	pkt := buildIPv4Packet(t,
+		netip.MustParseAddr("10.0.0.1"),
+		netip.MustParseAddr("10.0.0.2"),
+		protoTCP, 12345, 443)
+
+	sess.Offer(pkt, true)
+	sess.Stop()
+
+	data := buf.Bytes()
+	require.Greater(t, len(data), 24, "should have global header + at least one packet")
+
+	// Verify global header
+	assert.Equal(t, uint32(pcapMagic), binary.LittleEndian.Uint32(data[0:4]))
+	assert.Equal(t, uint32(linkTypeRaw), binary.LittleEndian.Uint32(data[20:24]))
+
+	// Verify packet record
+	pktData := data[24:]
+	inclLen := binary.LittleEndian.Uint32(pktData[8:12])
+	assert.Equal(t, uint32(len(pkt)), inclLen)
+
+	stats := sess.Stats()
+	assert.Equal(t, int64(1), stats.Packets)
+	assert.Equal(t, int64(len(pkt)), stats.Bytes)
+	assert.Equal(t, int64(0), stats.Dropped)
+}
+
+func TestSession_TextOutput(t *testing.T) {
+	var buf bytes.Buffer
+	sess, err := NewSession(Options{
+		TextOutput: &buf,
+		BufSize:    16,
+	})
+	require.NoError(t, err)
+
+	pkt := buildIPv4Packet(t,
+		netip.MustParseAddr("10.0.0.1"),
+		netip.MustParseAddr("10.0.0.2"),
+		protoTCP, 12345, 443)
+
+	sess.Offer(pkt, false)
+	sess.Stop()
+
+	output := buf.String()
+	assert.Contains(t, output, "TCP")
+	assert.Contains(t, output, "10.0.0.1")
+	assert.Contains(t, output, "10.0.0.2")
+	assert.Contains(t, output, "443")
+	assert.Contains(t, output, "[IN   TCP]")
+}
+
+func TestSession_Filter(t *testing.T) {
+	var buf bytes.Buffer
+	sess, err := NewSession(Options{
+		Output:  &buf,
+		Matcher: &Filter{Port: 443},
+	})
+	require.NoError(t, err)
+
+	pktMatch := buildIPv4Packet(t,
+		netip.MustParseAddr("10.0.0.1"),
+		netip.MustParseAddr("10.0.0.2"),
+		protoTCP, 12345, 443)
+	pktNoMatch := buildIPv4Packet(t,
+		netip.MustParseAddr("10.0.0.1"),
+		netip.MustParseAddr("10.0.0.2"),
+		protoTCP, 12345, 80)
+
+	sess.Offer(pktMatch, true)
+	sess.Offer(pktNoMatch, true)
+	sess.Stop()
+
+	stats := sess.Stats()
+	assert.Equal(t, int64(1), stats.Packets, "only matching packet should be captured")
+}
+
+func TestSession_StopIdempotent(t *testing.T) {
+	var buf bytes.Buffer
+	sess, err := NewSession(Options{Output: &buf})
+	require.NoError(t, err)
+
+	sess.Stop()
+	sess.Stop() // should not panic or deadlock
+}
+
+func TestSession_OfferAfterStop(t *testing.T) {
+	var buf bytes.Buffer
+	sess, err := NewSession(Options{Output: &buf})
+	require.NoError(t, err)
+	sess.Stop()
+
+	pkt := buildIPv4Packet(t,
+		netip.MustParseAddr("10.0.0.1"),
+		netip.MustParseAddr("10.0.0.2"),
+		protoTCP, 12345, 443)
+	sess.Offer(pkt, true) // should not panic
+
+	assert.Equal(t, int64(0), sess.Stats().Packets)
+}
+
+func TestSession_Done(t *testing.T) {
+	var buf bytes.Buffer
+	sess, err := NewSession(Options{Output: &buf})
+	require.NoError(t, err)
+
+	select {
+	case <-sess.Done():
+		t.Fatal("Done should not be closed before Stop")
+	default:
+	}
+
+	sess.Stop()
+
+	select {
+	case <-sess.Done():
+	case <-time.After(time.Second):
+		t.Fatal("Done should be closed after Stop")
+	}
+}
+
+func TestSession_RequiresOutput(t *testing.T) {
+	_, err := NewSession(Options{})
+	assert.Error(t, err)
+}

util/capture/text.go

@@ -0,0 +1,638 @@
+package capture
+
+import (
+	"encoding/binary"
+	"fmt"
+	"io"
+	"net/netip"
+	"strings"
+	"time"
+
+	"github.com/google/gopacket"
+	"github.com/google/gopacket/layers"
+)
+
+// TextWriter writes human-readable one-line-per-packet summaries.
+// It is not safe for concurrent use; callers must serialize access.
+type TextWriter struct {
+	w       io.Writer
+	verbose bool
+	ascii   bool
+	flows   map[dirKey]uint32
+}
+
+type dirKey struct {
+	src netip.AddrPort
+	dst netip.AddrPort
+}
+
+// NewTextWriter creates a text formatter that writes to w.
+func NewTextWriter(w io.Writer, verbose, ascii bool) *TextWriter {
+	return &TextWriter{
+		w:       w,
+		verbose: verbose,
+		ascii:   ascii,
+		flows:   make(map[dirKey]uint32),
+	}
+}
+
+// tag formats the fixed-width "[DIR PROTO]" prefix with right-aligned protocol.
+func tag(dir Direction, proto string) string {
+	return fmt.Sprintf("[%-3s %4s]", dir, proto)
+}
+
+// WritePacket formats and writes a single packet line.
+func (tw *TextWriter) WritePacket(ts time.Time, data []byte, dir Direction) error {
+	ts = ts.Local()
+	info, ok := parsePacketInfo(data)
+	if !ok {
+		_, err := fmt.Fprintf(tw.w, "%s [%-3s    ?] ??? len=%d\n",
+			ts.Format("15:04:05.000000"), dir, len(data))
+		return err
+	}
+
+	timeStr := ts.Format("15:04:05.000000")
+
+	var err error
+	switch info.proto {
+	case protoTCP:
+		err = tw.writeTCP(timeStr, dir, &info, data)
+	case protoUDP:
+		err = tw.writeUDP(timeStr, dir, &info, data)
+	case protoICMP:
+		err = tw.writeICMPv4(timeStr, dir, &info, data)
+	case protoICMPv6:
+		err = tw.writeICMPv6(timeStr, dir, &info, data)
+	default:
+		var verbose string
+		if tw.verbose {
+			verbose = tw.verboseIP(data, info.family)
+		}
+		_, err = fmt.Fprintf(tw.w, "%s %s %s > %s length %d%s\n",
+			timeStr, tag(dir, fmt.Sprintf("P%d", info.proto)),
+			info.srcIP, info.dstIP, len(data)-info.hdrLen, verbose)
+	}
+	return err
+}
+
+func (tw *TextWriter) writeTCP(timeStr string, dir Direction, info *packetInfo, data []byte) error {
+	tcp := &layers.TCP{}
+	if err := tcp.DecodeFromBytes(data[info.hdrLen:], gopacket.NilDecodeFeedback); err != nil {
+		return tw.writeFallback(timeStr, dir, "TCP", info, data)
+	}
+
+	flags := tcpFlagsStr(tcp)
+	plen := len(tcp.Payload)
+
+	// Protocol annotation
+	var annotation string
+	if plen > 0 {
+		annotation = annotatePayload(tcp.Payload)
+	}
+
+	if !tw.verbose {
+		_, err := fmt.Fprintf(tw.w, "%s %s %s:%d > %s:%d [%s] length %d%s\n",
+			timeStr, tag(dir, "TCP"),
+			info.srcIP, info.srcPort, info.dstIP, info.dstPort,
+			flags, plen, annotation)
+		if err != nil {
+			return err
+		}
+		if tw.ascii && plen > 0 {
+			return tw.writeASCII(tcp.Payload)
+		}
+		return nil
+	}
+
+	relSeq, relAck := tw.relativeSeqAck(info, tcp.Seq, tcp.Ack)
+
+	var seqStr string
+	if plen > 0 {
+		seqStr = fmt.Sprintf(", seq %d:%d", relSeq, relSeq+uint32(plen))
+	} else {
+		seqStr = fmt.Sprintf(", seq %d", relSeq)
+	}
+
+	var ackStr string
+	if tcp.ACK {
+		ackStr = fmt.Sprintf(", ack %d", relAck)
+	}
+
+	var opts string
+	if s := formatTCPOptions(tcp.Options); s != "" {
+		opts = ", options [" + s + "]"
+	}
+
+	verbose := tw.verboseIP(data, info.family)
+
+	_, err := fmt.Fprintf(tw.w, "%s %s %s:%d > %s:%d [%s]%s%s, win %d%s, length %d%s%s\n",
+		timeStr, tag(dir, "TCP"),
+		info.srcIP, info.srcPort, info.dstIP, info.dstPort,
+		flags, seqStr, ackStr, tcp.Window, opts, plen, annotation, verbose)
+	if err != nil {
+		return err
+	}
+	if tw.ascii && plen > 0 {
+		return tw.writeASCII(tcp.Payload)
+	}
+	return nil
+}
+
+func (tw *TextWriter) writeUDP(timeStr string, dir Direction, info *packetInfo, data []byte) error {
+	udp := &layers.UDP{}
+	if err := udp.DecodeFromBytes(data[info.hdrLen:], gopacket.NilDecodeFeedback); err != nil {
+		return tw.writeFallback(timeStr, dir, "UDP", info, data)
+	}
+
+	plen := len(udp.Payload)
+
+	// DNS replaces the entire line format
+	if plen > 0 && isDNSPort(info.srcPort, info.dstPort) {
+		if s := formatDNSPayload(udp.Payload); s != "" {
+			var verbose string
+			if tw.verbose {
+				verbose = tw.verboseIP(data, info.family)
+			}
+			_, err := fmt.Fprintf(tw.w, "%s %s %s:%d > %s:%d %s%s\n",
+				timeStr, tag(dir, "UDP"),
+				info.srcIP, info.srcPort, info.dstIP, info.dstPort,
+				s, verbose)
+			return err
+		}
+	}
+
+	var verbose string
+	if tw.verbose {
+		verbose = tw.verboseIP(data, info.family)
+	}
+	_, err := fmt.Fprintf(tw.w, "%s %s %s:%d > %s:%d length %d%s\n",
+		timeStr, tag(dir, "UDP"),
+		info.srcIP, info.srcPort, info.dstIP, info.dstPort,
+		plen, verbose)
+	if err != nil {
+		return err
+	}
+	if tw.ascii && plen > 0 {
+		return tw.writeASCII(udp.Payload)
+	}
+	return nil
+}
+
+func (tw *TextWriter) writeICMPv4(timeStr string, dir Direction, info *packetInfo, data []byte) error {
+	icmp := &layers.ICMPv4{}
+	if err := icmp.DecodeFromBytes(data[info.hdrLen:], gopacket.NilDecodeFeedback); err != nil {
+		return tw.writeFallback(timeStr, dir, "ICMP", info, data)
+	}
+
+	var detail string
+	if icmp.TypeCode.Type() == layers.ICMPv4TypeEchoRequest || icmp.TypeCode.Type() == layers.ICMPv4TypeEchoReply {
+		detail = fmt.Sprintf("%s, id %d, seq %d", icmp.TypeCode.String(), icmp.Id, icmp.Seq)
+	} else {
+		detail = icmp.TypeCode.String()
+	}
+
+	var verbose string
+	if tw.verbose {
+		verbose = tw.verboseIP(data, info.family)
+	}
+	_, err := fmt.Fprintf(tw.w, "%s %s %s > %s %s, length %d%s\n",
+		timeStr, tag(dir, "ICMP"), info.srcIP, info.dstIP, detail, len(data)-info.hdrLen, verbose)
+	return err
+}
+
+func (tw *TextWriter) writeICMPv6(timeStr string, dir Direction, info *packetInfo, data []byte) error {
+	icmp := &layers.ICMPv6{}
+	if err := icmp.DecodeFromBytes(data[info.hdrLen:], gopacket.NilDecodeFeedback); err != nil {
+		return tw.writeFallback(timeStr, dir, "ICMP", info, data)
+	}
+
+	var verbose string
+	if tw.verbose {
+		verbose = tw.verboseIP(data, info.family)
+	}
+	_, err := fmt.Fprintf(tw.w, "%s %s %s > %s %s, length %d%s\n",
+		timeStr, tag(dir, "ICMP"), info.srcIP, info.dstIP, icmp.TypeCode.String(), len(data)-info.hdrLen, verbose)
+	return err
+}
+
+func (tw *TextWriter) writeFallback(timeStr string, dir Direction, proto string, info *packetInfo, data []byte) error {
+	_, err := fmt.Fprintf(tw.w, "%s %s %s:%d > %s:%d length %d\n",
+		timeStr, tag(dir, proto),
+		info.srcIP, info.srcPort, info.dstIP, info.dstPort,
+		len(data)-info.hdrLen)
+	return err
+}
+
+func (tw *TextWriter) verboseIP(data []byte, family uint8) string {
+	return fmt.Sprintf(", ttl %d, id %d, iplen %d",
+		ipTTL(data, family), ipID(data, family), len(data))
+}
+
+// relativeSeqAck returns seq/ack relative to the first seen value per direction.
+func (tw *TextWriter) relativeSeqAck(info *packetInfo, seq, ack uint32) (relSeq, relAck uint32) {
+	fwd := dirKey{
+		src: netip.AddrPortFrom(info.srcIP, info.srcPort),
+		dst: netip.AddrPortFrom(info.dstIP, info.dstPort),
+	}
+	rev := dirKey{
+		src: netip.AddrPortFrom(info.dstIP, info.dstPort),
+		dst: netip.AddrPortFrom(info.srcIP, info.srcPort),
+	}
+
+	if isn, ok := tw.flows[fwd]; ok {
+		relSeq = seq - isn
+	} else {
+		tw.flows[fwd] = seq
+	}
+
+	if isn, ok := tw.flows[rev]; ok {
+		relAck = ack - isn
+	} else {
+		relAck = ack
+	}
+
+	return relSeq, relAck
+}
+
+// writeASCII prints payload bytes as printable ASCII.
+func (tw *TextWriter) writeASCII(payload []byte) error {
+	if len(payload) == 0 {
+		return nil
+	}
+	buf := make([]byte, len(payload))
+	for i, b := range payload {
+		switch {
+		case b >= 0x20 && b < 0x7f:
+			buf[i] = b
+		case b == '\n' || b == '\r' || b == '\t':
+			buf[i] = b
+		default:
+			buf[i] = '.'
+		}
+	}
+	_, err := fmt.Fprintf(tw.w, "%s\n", buf)
+	return err
+}
+
+// --- TCP helpers ---
+
+func ipTTL(data []byte, family uint8) uint8 {
+	if family == 4 && len(data) > 8 {
+		return data[8]
+	}
+	if family == 6 && len(data) > 7 {
+		return data[7]
+	}
+	return 0
+}
+
+func ipID(data []byte, family uint8) uint16 {
+	if family == 4 && len(data) >= 6 {
+		return binary.BigEndian.Uint16(data[4:6])
+	}
+	return 0
+}
+
+func tcpFlagsStr(tcp *layers.TCP) string {
+	var buf [6]byte
+	n := 0
+	if tcp.SYN {
+		buf[n] = 'S'
+		n++
+	}
+	if tcp.FIN {
+		buf[n] = 'F'
+		n++
+	}
+	if tcp.RST {
+		buf[n] = 'R'
+		n++
+	}
+	if tcp.PSH {
+		buf[n] = 'P'
+		n++
+	}
+	if tcp.ACK {
+		buf[n] = '.'
+		n++
+	}
+	if tcp.URG {
+		buf[n] = 'U'
+		n++
+	}
+	if n == 0 {
+		return "none"
+	}
+	return string(buf[:n])
+}
+
+func formatTCPOptions(opts []layers.TCPOption) string {
+	var parts []string
+	for _, opt := range opts {
+		switch opt.OptionType {
+		case layers.TCPOptionKindEndList:
+			return strings.Join(parts, ",")
+		case layers.TCPOptionKindNop:
+			parts = append(parts, "nop")
+		case layers.TCPOptionKindMSS:
+			if len(opt.OptionData) == 2 {
+				parts = append(parts, fmt.Sprintf("mss %d", binary.BigEndian.Uint16(opt.OptionData)))
+			}
+		case layers.TCPOptionKindWindowScale:
+			if len(opt.OptionData) == 1 {
+				parts = append(parts, fmt.Sprintf("wscale %d", opt.OptionData[0]))
+			}
+		case layers.TCPOptionKindSACKPermitted:
+			parts = append(parts, "sackOK")
+		case layers.TCPOptionKindSACK:
+			blocks := len(opt.OptionData) / 8
+			parts = append(parts, fmt.Sprintf("sack %d", blocks))
+		case layers.TCPOptionKindTimestamps:
+			if len(opt.OptionData) == 8 {
+				tsval := binary.BigEndian.Uint32(opt.OptionData[0:4])
+				tsecr := binary.BigEndian.Uint32(opt.OptionData[4:8])
+				parts = append(parts, fmt.Sprintf("TS val %d ecr %d", tsval, tsecr))
+			}
+		}
+	}
+	return strings.Join(parts, ",")
+}
+
+// --- Protocol annotation ---
+
+// annotatePayload returns a protocol annotation string for known application protocols.
+func annotatePayload(payload []byte) string {
+	if len(payload) < 4 {
+		return ""
+	}
+
+	s := string(payload)
+
+	// SSH banner: "SSH-2.0-OpenSSH_9.6\r\n"
+	if strings.HasPrefix(s, "SSH-") {
+		if end := strings.IndexByte(s, '\r'); end > 0 && end < 256 {
+			return ": " + s[:end]
+		}
+	}
+
+	// TLS records
+	if ann := annotateTLS(payload); ann != "" {
+		return ": " + ann
+	}
+
+	// HTTP request or response
+	for _, method := range [...]string{"GET ", "POST ", "PUT ", "DELETE ", "HEAD ", "PATCH ", "OPTIONS ", "CONNECT "} {
+		if strings.HasPrefix(s, method) {
+			if end := strings.IndexByte(s, '\r'); end > 0 && end < 200 {
+				return ": " + s[:end]
+			}
+		}
+	}
+	if strings.HasPrefix(s, "HTTP/") {
+		if end := strings.IndexByte(s, '\r'); end > 0 && end < 200 {
+			return ": " + s[:end]
+		}
+	}
+
+	return ""
+}
+
+// annotateTLS returns a description for TLS handshake and alert records.
+func annotateTLS(data []byte) string {
+	if len(data) < 6 {
+		return ""
+	}
+
+	switch data[0] {
+	case 0x16:
+		return annotateTLSHandshake(data)
+	case 0x15:
+		return annotateTLSAlert(data)
+	}
+	return ""
+}
+
+func annotateTLSHandshake(data []byte) string {
+	if len(data) < 10 {
+		return ""
+	}
+	switch data[5] {
+	case 0x01:
+		if sni := extractSNI(data); sni != "" {
+			return "TLS ClientHello SNI=" + sni
+		}
+		return "TLS ClientHello"
+	case 0x02:
+		return "TLS ServerHello"
+	}
+	return ""
+}
+
+func annotateTLSAlert(data []byte) string {
+	if len(data) < 7 {
+		return ""
+	}
+	severity := "warning"
+	if data[5] == 2 {
+		severity = "fatal"
+	}
+	return fmt.Sprintf("TLS Alert %s %s", severity, tlsAlertDesc(data[6]))
+}
+
+func tlsAlertDesc(code byte) string {
+	switch code {
+	case 0:
+		return "close_notify"
+	case 10:
+		return "unexpected_message"
+	case 40:
+		return "handshake_failure"
+	case 42:
+		return "bad_certificate"
+	case 43:
+		return "unsupported_certificate"
+	case 44:
+		return "certificate_revoked"
+	case 45:
+		return "certificate_expired"
+	case 48:
+		return "unknown_ca"
+	case 49:
+		return "access_denied"
+	case 50:
+		return "decode_error"
+	case 70:
+		return "protocol_version"
+	case 80:
+		return "internal_error"
+	case 86:
+		return "inappropriate_fallback"
+	case 90:
+		return "user_canceled"
+	case 112:
+		return "unrecognized_name"
+	default:
+		return fmt.Sprintf("alert(%d)", code)
+	}
+}
+
+// extractSNI parses a TLS ClientHello and returns the SNI server name.
+func extractSNI(data []byte) string {
+	if len(data) < 6 || data[0] != 0x16 {
+		return ""
+	}
+	recordLen := int(binary.BigEndian.Uint16(data[3:5]))
+	handshake := data[5:]
+	if len(handshake) > recordLen {
+		handshake = handshake[:recordLen]
+	}
+
+	if len(handshake) < 4 || handshake[0] != 0x01 {
+		return ""
+	}
+	hsLen := int(handshake[1])<<16 | int(handshake[2])<<8 | int(handshake[3])
+	body := handshake[4:]
+	if len(body) > hsLen {
+		body = body[:hsLen]
+	}
+
+	extPos := clientHelloExtensionsOffset(body)
+	if extPos < 0 {
+		return ""
+	}
+	return findSNIExtension(body, extPos)
+}
+
+// clientHelloExtensionsOffset returns the byte offset where extensions begin
+// within the ClientHello body, or -1 if the body is too short.
+func clientHelloExtensionsOffset(body []byte) int {
+	if len(body) < 38 {
+		return -1
+	}
+	pos := 34
+
+	if pos >= len(body) {
+		return -1
+	}
+	pos += 1 + int(body[pos]) // session ID
+
+	if pos+2 > len(body) {
+		return -1
+	}
+	pos += 2 + int(binary.BigEndian.Uint16(body[pos:pos+2])) // cipher suites
+
+	if pos >= len(body) {
+		return -1
+	}
+	pos += 1 + int(body[pos]) // compression methods
+
+	if pos+2 > len(body) {
+		return -1
+	}
+	return pos
+}
+
+func findSNIExtension(body []byte, pos int) string {
+	extLen := int(binary.BigEndian.Uint16(body[pos : pos+2]))
+	pos += 2
+	extEnd := pos + extLen
+	if extEnd > len(body) {
+		extEnd = len(body)
+	}
+
+	for pos+4 <= extEnd {
+		extType := binary.BigEndian.Uint16(body[pos : pos+2])
+		eLen := int(binary.BigEndian.Uint16(body[pos+2 : pos+4]))
+		pos += 4
+		if pos+eLen > extEnd {
+			break
+		}
+		if extType == 0 && eLen >= 5 {
+			nameLen := int(binary.BigEndian.Uint16(body[pos+3 : pos+5]))
+			if pos+5+nameLen <= extEnd {
+				return string(body[pos+5 : pos+5+nameLen])
+			}
+		}
+		pos += eLen
+	}
+	return ""
+}
+
+func isDNSPort(src, dst uint16) bool {
+	return src == 53 || dst == 53 || src == 5353 || dst == 5353
+}
+
+// formatDNSPayload parses DNS and returns a tcpdump-style summary.
+func formatDNSPayload(payload []byte) string {
+	d := &layers.DNS{}
+	if err := d.DecodeFromBytes(payload, gopacket.NilDecodeFeedback); err != nil {
+		return ""
+	}
+
+	rd := ""
+	if d.RD {
+		rd = "+"
+	}
+
+	if !d.QR {
+		return formatDNSQuery(d, rd, len(payload))
+	}
+	return formatDNSResponse(d, rd, len(payload))
+}
+
+func formatDNSQuery(d *layers.DNS, rd string, plen int) string {
+	if len(d.Questions) == 0 {
+		return fmt.Sprintf("%04x%s (%d)", d.ID, rd, plen)
+	}
+	q := d.Questions[0]
+	return fmt.Sprintf("%04x%s %s? %s. (%d)", d.ID, rd, q.Type, q.Name, plen)
+}
+
+func formatDNSResponse(d *layers.DNS, rd string, plen int) string {
+	anCount := d.ANCount
+	nsCount := d.NSCount
+	arCount := d.ARCount
+
+	if d.ResponseCode != layers.DNSResponseCodeNoErr {
+		return fmt.Sprintf("%04x %d/%d/%d %s (%d)", d.ID, anCount, nsCount, arCount, d.ResponseCode, plen)
+	}
+
+	if anCount > 0 && len(d.Answers) > 0 {
+		rr := d.Answers[0]
+		if rdata := shortRData(&rr); rdata != "" {
+			return fmt.Sprintf("%04x %d/%d/%d %s %s (%d)", d.ID, anCount, nsCount, arCount, rr.Type, rdata, plen)
+		}
+	}
+
+	return fmt.Sprintf("%04x %d/%d/%d (%d)", d.ID, anCount, nsCount, arCount, plen)
+}
+
+func shortRData(rr *layers.DNSResourceRecord) string {
+	switch rr.Type {
+	case layers.DNSTypeA, layers.DNSTypeAAAA:
+		if rr.IP != nil {
+			return rr.IP.String()
+		}
+	case layers.DNSTypeCNAME:
+		if len(rr.CNAME) > 0 {
+			return string(rr.CNAME) + "."
+		}
+	case layers.DNSTypePTR:
+		if len(rr.PTR) > 0 {
+			return string(rr.PTR) + "."
+		}
+	case layers.DNSTypeNS:
+		if len(rr.NS) > 0 {
+			return string(rr.NS) + "."
+		}
+	case layers.DNSTypeMX:
+		return fmt.Sprintf("%d %s.", rr.MX.Preference, rr.MX.Name)
+	case layers.DNSTypeTXT:
+		if len(rr.TXTs) > 0 {
+			return fmt.Sprintf("%q", string(rr.TXTs[0]))
+		}
+	case layers.DNSTypeSRV:
+		return fmt.Sprintf("%d %d %d %s.", rr.SRV.Priority, rr.SRV.Weight, rr.SRV.Port, rr.SRV.Name)
+	}
+	return ""
+}