Add per-connection user-approval prompts for VNC

client/internal/approval/broker.go

@@ -0,0 +1,188 @@
+// Package approval brokers per-attempt user-accept prompts for inbound
+// remote access (VNC today, SSH and others in the future). A caller pushes
+// a Prompt; the broker emits a SystemEvent on the daemon→UI stream and
+// blocks until the UI calls the daemon's RespondApproval RPC, the per-
+// request timeout fires, or no subscriber is connected. The latter case
+// fails closed so a backgrounded UI cannot silently bypass the gate.
+package approval
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"sync"
+	"time"
+
+	"github.com/google/uuid"
+	log "github.com/sirupsen/logrus"
+
+	"github.com/netbirdio/netbird/client/proto"
+)
+
+// Metadata keys the broker reserves on the emitted SystemEvent. Callers
+// should not set these themselves; values in Prompt.Metadata that collide
+// are overwritten by the broker.
+const (
+	MetaRequestID = "request_id"
+	MetaKind      = "kind"
+	MetaExpiresAt = "expires_at"
+)
+
+// Kind values for the well-known prompt subjects. New subsystems should
+// add a constant here so the UI can dispatch on a known string.
+const (
+	KindVNC = "vnc"
+	KindSSH = "ssh"
+)
+
+// DefaultTimeout is the wall-clock window the user has to accept or deny a
+// pending approval before the broker fails closed and returns ErrTimeout.
+// Kept well under typical VNC client and dashboard connection timeouts so
+// the RFB rejection actually reaches the browser instead of racing the
+// browser's own "connection timed out" message.
+const DefaultTimeout = 15 * time.Second
+
+// timeoutValue returns the active timeout. It's a var so tests in this
+// package can shorten the wait without exposing a setter on the public
+// API. Production code always sees DefaultTimeout.
+var timeoutValue = func() time.Duration { return DefaultTimeout }
+
+// ErrNoSubscriber indicates no UI is connected to consume the prompt.
+// The caller must reject the underlying connection (fail-closed).
+var ErrNoSubscriber = errors.New("no UI subscriber connected for approval")
+
+// ErrTimeout indicates the user did not respond within DefaultTimeout.
+var ErrTimeout = errors.New("approval timed out")
+
+// ErrDenied indicates the user explicitly denied the connection.
+var ErrDenied = errors.New("approval denied")
+
+// EventPublisher is the subset of peer.Status used to emit prompts.
+type EventPublisher interface {
+	PublishEvent(
+		severity proto.SystemEvent_Severity,
+		category proto.SystemEvent_Category,
+		msg string,
+		userMsg string,
+		metadata map[string]string,
+	)
+	HasEventSubscribers() bool
+}
+
+// Prompt describes the pending request shown to the user. Kind selects
+// the UI dispatch path (e.g. "vnc", "ssh"). Subject is the human-readable
+// one-liner the UI may show as a title or notification body. Metadata is
+// passed through verbatim and is the subsystem-specific payload (peer
+// name, source IP, mode, etc.).
+type Prompt struct {
+	Kind     string
+	Subject  string
+	Metadata map[string]string
+}
+
+// Decision carries the user's response to an approval prompt. ViewOnly is
+// only meaningful when Accept is true; it lets the host grant the
+// connection but signal the requester that input control is withheld.
+type Decision struct {
+	Accept   bool
+	ViewOnly bool
+}
+
+// Broker holds in-flight approval requests keyed by request ID.
+type Broker struct {
+	pub EventPublisher
+
+	mu      sync.Mutex
+	pending map[string]chan Decision
+}
+
+// New returns a broker that publishes prompts via pub.
+func New(pub EventPublisher) *Broker {
+	return &Broker{
+		pub:     pub,
+		pending: make(map[string]chan Decision),
+	}
+}
+
+// Request emits a SystemEvent for p and blocks until the UI calls Respond,
+// ctx is cancelled, or DefaultTimeout elapses. Returns a Decision when
+// the user replied; ErrDenied / ErrTimeout / ErrNoSubscriber / ctx.Err
+// otherwise. Callers must treat any non-nil error as a deny.
+func (b *Broker) Request(ctx context.Context, p Prompt) (Decision, error) {
+	var zero Decision
+	if b == nil || b.pub == nil {
+		return zero, fmt.Errorf("approval broker not configured")
+	}
+	if !b.pub.HasEventSubscribers() {
+		return zero, ErrNoSubscriber
+	}
+
+	id := uuid.NewString()
+	resp := make(chan Decision, 1)
+
+	b.mu.Lock()
+	b.pending[id] = resp
+	b.mu.Unlock()
+
+	defer b.dropPending(id)
+
+	timeout := timeoutValue()
+	expiresAt := time.Now().Add(timeout)
+	meta := make(map[string]string, len(p.Metadata)+3)
+	for k, v := range p.Metadata {
+		meta[k] = v
+	}
+	meta[MetaRequestID] = id
+	meta[MetaKind] = p.Kind
+	meta[MetaExpiresAt] = expiresAt.UTC().Format(time.RFC3339)
+
+	subject := p.Subject
+	if subject == "" {
+		subject = fmt.Sprintf("%s connection requires approval", p.Kind)
+	}
+	b.pub.PublishEvent(proto.SystemEvent_INFO, proto.SystemEvent_APPROVAL, subject, subject, meta)
+	log.Debugf("approval request %s (%s) emitted: %s", id, p.Kind, subject)
+
+	timer := time.NewTimer(timeout)
+	defer timer.Stop()
+
+	select {
+	case d := <-resp:
+		if !d.Accept {
+			return zero, ErrDenied
+		}
+		return d, nil
+	case <-timer.C:
+		return zero, ErrTimeout
+	case <-ctx.Done():
+		return zero, ctx.Err()
+	}
+}
+
+// Respond delivers the user's decision for id. Returns true when a pending
+// request matched and was woken, false when id was unknown or already done.
+func (b *Broker) Respond(id string, d Decision) bool {
+	if b == nil {
+		return false
+	}
+	b.mu.Lock()
+	ch, ok := b.pending[id]
+	if ok {
+		delete(b.pending, id)
+	}
+	b.mu.Unlock()
+	if !ok {
+		return false
+	}
+	select {
+	case ch <- d:
+	default:
+	}
+	return true
+}
+
+func (b *Broker) dropPending(id string) {
+	b.mu.Lock()
+	delete(b.pending, id)
+	b.mu.Unlock()
+}

client/internal/approval/broker_test.go

@@ -0,0 +1,434 @@
+package approval
+
+import (
+	"context"
+	"sync"
+	"sync/atomic"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+
+	"github.com/netbirdio/netbird/client/proto"
+)
+
+// fakePublisher records published events and reports whether subscribers
+// are connected. The subscribers flag is the security-critical signal:
+// when false the broker must refuse to emit and the gate must fail closed.
+type fakePublisher struct {
+	mu          sync.Mutex
+	subscribers bool
+	events      []*proto.SystemEvent
+}
+
+func (p *fakePublisher) PublishEvent(
+	severity proto.SystemEvent_Severity,
+	category proto.SystemEvent_Category,
+	msg string,
+	userMsg string,
+	metadata map[string]string,
+) {
+	p.mu.Lock()
+	p.events = append(p.events, &proto.SystemEvent{
+		Severity:    severity,
+		Category:    category,
+		Message:     msg,
+		UserMessage: userMsg,
+		Metadata:    metadata,
+	})
+	p.mu.Unlock()
+}
+
+func (p *fakePublisher) HasEventSubscribers() bool {
+	p.mu.Lock()
+	defer p.mu.Unlock()
+	return p.subscribers
+}
+
+func (p *fakePublisher) lastEvent(t *testing.T) *proto.SystemEvent {
+	t.Helper()
+	p.mu.Lock()
+	defer p.mu.Unlock()
+	require.NotEmpty(t, p.events, "publisher saw no events")
+	return p.events[len(p.events)-1]
+}
+
+func (p *fakePublisher) eventCount() int {
+	p.mu.Lock()
+	defer p.mu.Unlock()
+	return len(p.events)
+}
+
+// TestRequestNoSubscriberFailsClosed is the core fail-closed invariant:
+// when the UI is not subscribed, the broker must refuse without emitting
+// an event or arming a waiter. A regression here is a silent bypass.
+func TestRequestNoSubscriberFailsClosed(t *testing.T) {
+	pub := &fakePublisher{subscribers: false}
+	b := New(pub)
+
+	_, err := b.Request(context.Background(), Prompt{Kind: KindVNC, Subject: "test"})
+	assert.ErrorIs(t, err, ErrNoSubscriber)
+	assert.Equal(t, 0, pub.eventCount(), "no event must be emitted when fail-closed")
+
+	b.mu.Lock()
+	pending := len(b.pending)
+	b.mu.Unlock()
+	assert.Equal(t, 0, pending, "no waiter must be registered on fail-closed")
+}
+
+// TestRequestTimeoutDenies verifies that a request without a UI response
+// returns ErrTimeout (deny) rather than nil (silent accept). Uses a short
+// per-test broker timeout via Respond after the fact to keep the test fast.
+func TestRequestTimeoutDenies(t *testing.T) {
+	// Replace DefaultTimeout for the lifetime of this test.
+	orig := DefaultTimeout
+	defaultTimeout(t, 60*time.Millisecond)
+	defer defaultTimeout(t, orig)
+
+	pub := &fakePublisher{subscribers: true}
+	b := New(pub)
+
+	start := time.Now()
+	_, err := b.Request(context.Background(), Prompt{Kind: KindVNC, Subject: "test"})
+	assert.ErrorIs(t, err, ErrTimeout, "missing user response must yield ErrTimeout, not nil")
+	assert.GreaterOrEqual(t, time.Since(start), 50*time.Millisecond, "timeout fired prematurely")
+}
+
+// TestRequestDenied returns ErrDenied when the UI responds with false.
+func TestRequestDenied(t *testing.T) {
+	pub := &fakePublisher{subscribers: true}
+	b := New(pub)
+
+	var requestID string
+	done := make(chan error, 1)
+	go func() {
+		done <- requestErr(b, context.Background(), Prompt{Kind: KindVNC, Subject: "test"})
+	}()
+
+	requestID = waitForRequestID(t, pub)
+	require.True(t, b.Respond(requestID, Decision{Accept: false}))
+
+	select {
+	case err := <-done:
+		assert.ErrorIs(t, err, ErrDenied)
+	case <-time.After(time.Second):
+		t.Fatal("Request did not return after Respond(false)")
+	}
+}
+
+// TestRequestAccepted is the happy path. Failure here doesn't bypass the
+// gate but breaks the feature.
+func TestRequestAccepted(t *testing.T) {
+	pub := &fakePublisher{subscribers: true}
+	b := New(pub)
+
+	done := make(chan error, 1)
+	go func() {
+		done <- requestErr(b, context.Background(), Prompt{Kind: KindVNC, Subject: "test"})
+	}()
+
+	id := waitForRequestID(t, pub)
+	require.True(t, b.Respond(id, Decision{Accept: true}))
+
+	select {
+	case err := <-done:
+		assert.NoError(t, err)
+	case <-time.After(time.Second):
+		t.Fatal("Request did not return after Respond(true)")
+	}
+}
+
+// TestRequestCtxCancelDenies verifies that an upstream cancel (e.g. the
+// engine shutting down mid-prompt) returns the cancel error rather than
+// nil. A nil here would be a silent bypass on shutdown races.
+func TestRequestCtxCancelDenies(t *testing.T) {
+	pub := &fakePublisher{subscribers: true}
+	b := New(pub)
+
+	ctx, cancel := context.WithCancel(context.Background())
+	done := make(chan error, 1)
+	go func() {
+		done <- requestErr(b, ctx, Prompt{Kind: KindVNC, Subject: "test"})
+	}()
+
+	// Wait until the prompt is in flight so cancel races a live waiter.
+	_ = waitForRequestID(t, pub)
+	cancel()
+
+	select {
+	case err := <-done:
+		assert.ErrorIs(t, err, context.Canceled)
+	case <-time.After(time.Second):
+		t.Fatal("Request did not return after ctx cancel")
+	}
+}
+
+// TestRespondUnknownIsNoop ensures a stray RespondApproval RPC cannot
+// affect or accidentally accept any in-flight request whose id it doesn't
+// match. Also confirms it doesn't panic.
+func TestRespondUnknownIsNoop(t *testing.T) {
+	pub := &fakePublisher{subscribers: true}
+	b := New(pub)
+
+	// No in-flight prompts: Respond returns false.
+	assert.False(t, b.Respond("does-not-exist", Decision{Accept: true}))
+
+	// With an in-flight prompt, a wrong id still returns false and the
+	// prompt remains armed (eventually timing out as a deny).
+	defaultTimeout(t, 60*time.Millisecond)
+	defer defaultTimeout(t, DefaultTimeout)
+
+	done := make(chan error, 1)
+	go func() {
+		done <- requestErr(b, context.Background(), Prompt{Kind: KindVNC})
+	}()
+	realID := waitForRequestID(t, pub)
+	assert.False(t, b.Respond("totally-bogus", Decision{Accept: true}), "unknown id must not match")
+	assert.NotEqual(t, "totally-bogus", realID)
+
+	select {
+	case err := <-done:
+		assert.ErrorIs(t, err, ErrTimeout, "armed prompt must still time out, not accept")
+	case <-time.After(time.Second):
+		t.Fatal("prompt did not resolve")
+	}
+}
+
+// TestRespondAfterTimeoutNoop confirms a late accept response can't
+// retroactively flip a denied (timed-out) request. The dropPending defer
+// in Request must have removed the entry by the time Respond races in.
+func TestRespondAfterTimeoutNoop(t *testing.T) {
+	defaultTimeout(t, 30*time.Millisecond)
+	defer defaultTimeout(t, DefaultTimeout)
+
+	pub := &fakePublisher{subscribers: true}
+	b := New(pub)
+
+	done := make(chan error, 1)
+	go func() {
+		done <- requestErr(b, context.Background(), Prompt{Kind: KindVNC})
+	}()
+	id := waitForRequestID(t, pub)
+
+	select {
+	case err := <-done:
+		require.ErrorIs(t, err, ErrTimeout)
+	case <-time.After(time.Second):
+		t.Fatal("prompt did not time out")
+	}
+
+	assert.False(t, b.Respond(id, Decision{Accept: true}), "late respond must be no-op")
+}
+
+// TestRespondDoubleNoop ensures a duplicate ack from the UI doesn't leak
+// past the matched waiter or panic on a closed/full channel.
+func TestRespondDoubleNoop(t *testing.T) {
+	pub := &fakePublisher{subscribers: true}
+	b := New(pub)
+
+	done := make(chan error, 1)
+	go func() {
+		done <- requestErr(b, context.Background(), Prompt{Kind: KindVNC})
+	}()
+	id := waitForRequestID(t, pub)
+	require.True(t, b.Respond(id, Decision{Accept: true}))
+	assert.False(t, b.Respond(id, Decision{Accept: false}), "second response must be no-op")
+
+	select {
+	case err := <-done:
+		assert.NoError(t, err)
+	case <-time.After(time.Second):
+		t.Fatal("prompt did not resolve")
+	}
+}
+
+// TestNilBrokerRequestErrors guards the engine pre-init path where the
+// broker may not yet exist (or its publisher is nil): Request must
+// error, never silently accept.
+func TestNilBrokerRequestErrors(t *testing.T) {
+	var b *Broker
+	_, err := b.Request(context.Background(), Prompt{Kind: KindVNC})
+	assert.Error(t, err, "nil broker must error, never silently accept")
+
+	b2 := New(nil)
+	_, err = b2.Request(context.Background(), Prompt{Kind: KindVNC})
+	assert.Error(t, err, "broker with nil publisher must error, never silently accept")
+}
+
+// TestPromptMetadataInjected confirms the broker stamps request_id, kind,
+// and expires_at on the emitted event. The UI relies on these keys; if
+// they are dropped, the user cannot route the prompt and the response
+// path breaks (which fails closed via timeout).
+func TestPromptMetadataInjected(t *testing.T) {
+	pub := &fakePublisher{subscribers: true}
+	b := New(pub)
+
+	done := make(chan error, 1)
+	go func() {
+		done <- requestErr(b, context.Background(), Prompt{
+			Kind:     KindVNC,
+			Subject:  "VNC connection from peerA",
+			Metadata: map[string]string{"peer_name": "peerA"},
+		})
+	}()
+
+	id := waitForRequestID(t, pub)
+	ev := pub.lastEvent(t)
+
+	assert.Equal(t, proto.SystemEvent_APPROVAL, ev.Category)
+	assert.Equal(t, KindVNC, ev.Metadata[MetaKind])
+	assert.Equal(t, id, ev.Metadata[MetaRequestID])
+	assert.NotEmpty(t, ev.Metadata[MetaExpiresAt])
+	assert.Equal(t, "peerA", ev.Metadata["peer_name"], "caller metadata must pass through")
+
+	require.True(t, b.Respond(id, Decision{Accept: true}))
+	<-done
+}
+
+// TestConcurrentRequests verifies that two concurrent prompts are tracked
+// independently. A bug that aliases ids would let one Respond unblock
+// the wrong waiter (a silent accept across prompts).
+func TestConcurrentRequests(t *testing.T) {
+	pub := &fakePublisher{subscribers: true}
+	b := New(pub)
+
+	const n = 20
+	results := make(chan error, n)
+	for i := 0; i < n; i++ {
+		go func() {
+			results <- requestErr(b, context.Background(), Prompt{Kind: KindVNC})
+		}()
+	}
+
+	ids := waitForNRequestIDs(t, pub, n)
+	require.Len(t, ids, n)
+
+	// Deny exactly half, accept the rest. Track outcome per id so we can
+	// match each Request's return value against the response we sent.
+	denySet := make(map[string]bool, n)
+	for i, id := range ids {
+		deny := i%2 == 0
+		denySet[id] = deny
+		require.True(t, b.Respond(id, Decision{Accept: !deny}))
+	}
+
+	// Collect all returns and check no nil errors slipped past a deny.
+	var accepted, denied atomic.Int32
+	for i := 0; i < n; i++ {
+		select {
+		case err := <-results:
+			if err == nil {
+				accepted.Add(1)
+			} else {
+				assert.ErrorIs(t, err, ErrDenied)
+				denied.Add(1)
+			}
+		case <-time.After(2 * time.Second):
+			t.Fatalf("only got %d/%d responses", i, n)
+		}
+	}
+	assert.Equal(t, int32(n/2), denied.Load())
+	assert.Equal(t, int32(n/2), accepted.Load())
+}
+
+// waitForRequestID blocks until the publisher sees its next event and
+// returns the request_id stamped on it.
+func waitForRequestID(t *testing.T, pub *fakePublisher) string {
+	t.Helper()
+	deadline := time.Now().Add(2 * time.Second)
+	for time.Now().Before(deadline) {
+		pub.mu.Lock()
+		count := len(pub.events)
+		var id string
+		if count > 0 {
+			id = pub.events[count-1].Metadata[MetaRequestID]
+		}
+		pub.mu.Unlock()
+		if id != "" {
+			return id
+		}
+		time.Sleep(2 * time.Millisecond)
+	}
+	t.Fatal("timeout waiting for emitted event")
+	return ""
+}
+
+func waitForNRequestIDs(t *testing.T, pub *fakePublisher, n int) []string {
+	t.Helper()
+	deadline := time.Now().Add(2 * time.Second)
+	for time.Now().Before(deadline) {
+		pub.mu.Lock()
+		count := len(pub.events)
+		pub.mu.Unlock()
+		if count >= n {
+			break
+		}
+		time.Sleep(2 * time.Millisecond)
+	}
+	pub.mu.Lock()
+	defer pub.mu.Unlock()
+	out := make([]string, 0, len(pub.events))
+	seen := make(map[string]struct{}, len(pub.events))
+	for _, ev := range pub.events {
+		id := ev.Metadata[MetaRequestID]
+		if id == "" {
+			continue
+		}
+		if _, dup := seen[id]; dup {
+			continue
+		}
+		seen[id] = struct{}{}
+		out = append(out, id)
+	}
+	if len(out) < n {
+		t.Fatalf("only got %d/%d request ids", len(out), n)
+	}
+	return out
+}
+
+// defaultTimeout swaps the broker's per-request wall-clock window so the
+// timeout tests run quickly. Restores the prior value on the next call.
+func defaultTimeout(t *testing.T, d time.Duration) {
+	t.Helper()
+	if d <= 0 {
+		t.Fatal("defaultTimeout must be > 0")
+	}
+	timeoutValue = func() time.Duration { return d }
+}
+
+// requestErr wraps Broker.Request to drop the Decision when tests only
+// care about the error path. Keeps the goroutine bodies tight.
+func requestErr(b *Broker, ctx context.Context, p Prompt) error {
+	_, err := b.Request(ctx, p)
+	return err
+}
+
+// TestRequestViewOnly checks the view-only outcome flows through Request's
+// Decision return without being silently swallowed.
+func TestRequestViewOnly(t *testing.T) {
+	pub := &fakePublisher{subscribers: true}
+	b := New(pub)
+
+	type result struct {
+		d   Decision
+		err error
+	}
+	done := make(chan result, 1)
+	go func() {
+		d, err := b.Request(context.Background(), Prompt{Kind: KindVNC})
+		done <- result{d, err}
+	}()
+
+	id := waitForRequestID(t, pub)
+	require.True(t, b.Respond(id, Decision{Accept: true, ViewOnly: true}))
+
+	select {
+	case r := <-done:
+		assert.NoError(t, r.err)
+		assert.True(t, r.d.Accept)
+		assert.True(t, r.d.ViewOnly, "ViewOnly must survive the round-trip")
+	case <-time.After(time.Second):
+		t.Fatal("view-only request did not resolve")
+	}
+}

client/internal/connect.go

@@ -563,6 +563,7 @@ func createEngineConfig(key wgtypes.Key, config *profilemanager.Config, peerConf
 		RosenpassPermissive:           config.RosenpassPermissive,
 		ServerSSHAllowed:              util.ReturnBoolWithDefaultTrue(config.ServerSSHAllowed),
 		ServerVNCAllowed:              config.ServerVNCAllowed != nil && *config.ServerVNCAllowed,
+		DisableVNCApproval:            config.DisableVNCApproval,
 		EnableSSHRoot:                 config.EnableSSHRoot,
 		EnableSSHSFTP:                 config.EnableSSHSFTP,
 		EnableSSHLocalPortForwarding:  config.EnableSSHLocalPortForwarding,

client/internal/debug/debug.go

@@ -639,6 +639,9 @@ func (g *BundleGenerator) addCommonConfigFields(configContent *strings.Builder)
 	if g.internalConfig.ServerVNCAllowed != nil {
 		configContent.WriteString(fmt.Sprintf("ServerVNCAllowed: %v\n", *g.internalConfig.ServerVNCAllowed))
 	}
+	if g.internalConfig.DisableVNCApproval != nil {
+		configContent.WriteString(fmt.Sprintf("DisableVNCApproval: %v\n", *g.internalConfig.DisableVNCApproval))
+	}
 
 	configContent.WriteString(fmt.Sprintf("DisableClientRoutes: %v\n", g.internalConfig.DisableClientRoutes))
 	configContent.WriteString(fmt.Sprintf("DisableServerRoutes: %v\n", g.internalConfig.DisableServerRoutes))

client/internal/engine.go

@@ -35,6 +35,7 @@ import (
 	"github.com/netbirdio/netbird/client/iface/udpmux"
 	"github.com/netbirdio/netbird/client/iface/wgaddr"
 	"github.com/netbirdio/netbird/client/internal/acl"
+	"github.com/netbirdio/netbird/client/internal/approval"
 	"github.com/netbirdio/netbird/client/internal/debug"
 	"github.com/netbirdio/netbird/client/internal/dns"
 	dnsconfig "github.com/netbirdio/netbird/client/internal/dns/config"
@@ -124,6 +125,7 @@ type EngineConfig struct {
 
 	ServerSSHAllowed              bool
 	ServerVNCAllowed              bool
+	DisableVNCApproval            *bool
 	EnableSSHRoot                 *bool
 	EnableSSHSFTP                 *bool
 	EnableSSHLocalPortForwarding  *bool
@@ -205,8 +207,9 @@ type Engine struct {
 
 	networkMonitor *networkmonitor.NetworkMonitor
 
-	sshServer sshServer
-	vncSrv    vncServer
+	sshServer      sshServer
+	vncSrv         vncServer
+	approvalBroker *approval.Broker
 
 	statusRecorder *peer.Status
 
@@ -287,6 +290,7 @@ func NewEngine(
 		TURNs:              []*stun.URI{},
 		networkSerial:      0,
 		statusRecorder:     services.StatusRecorder,
+		approvalBroker:     approval.New(services.StatusRecorder),
 		stateManager:       services.StateManager,
 		portForwardManager: portforward.NewManager(),
 		checks:             services.Checks,
@@ -2608,3 +2612,16 @@ func decodeRelayIP(b []byte) netip.Addr {
 	}
 	return ip.Unmap()
 }
+
+// RespondApproval relays the user's decision for a pending approval to
+// the broker. viewOnly is honoured only when accept is true. Returns
+// true when the request_id matched a live prompt.
+func (e *Engine) RespondApproval(requestID string, accept, viewOnly bool) bool {
+	if e == nil || e.approvalBroker == nil {
+		return false
+	}
+	return e.approvalBroker.Respond(requestID, approval.Decision{
+		Accept:   accept,
+		ViewOnly: accept && viewOnly,
+	})
+}

client/internal/engine_ssh.go

@@ -12,7 +12,7 @@ import (
 	firewallManager "github.com/netbirdio/netbird/client/firewall/manager"
 	"github.com/netbirdio/netbird/client/iface/netstack"
 	nftypes "github.com/netbirdio/netbird/client/internal/netflow/types"
-	sshauth "github.com/netbirdio/netbird/client/ssh/auth"
+	sshauth "github.com/netbirdio/netbird/shared/sessionauth"
 	sshconfig "github.com/netbirdio/netbird/client/ssh/config"
 	sshserver "github.com/netbirdio/netbird/client/ssh/server"
 	mgmProto "github.com/netbirdio/netbird/shared/management/proto"

client/internal/engine_vnc.go

@@ -11,9 +11,11 @@ import (
 	log "github.com/sirupsen/logrus"
 
 	firewallManager "github.com/netbirdio/netbird/client/firewall/manager"
+	"github.com/netbirdio/netbird/client/internal/approval"
 	"github.com/netbirdio/netbird/client/internal/metrics"
 	nftypes "github.com/netbirdio/netbird/client/internal/netflow/types"
-	sshauth "github.com/netbirdio/netbird/client/ssh/auth"
+	"github.com/netbirdio/netbird/client/internal/peer"
+	sshauth "github.com/netbirdio/netbird/shared/sessionauth"
 	vncserver "github.com/netbirdio/netbird/client/vnc/server"
 	mgmProto "github.com/netbirdio/netbird/shared/management/proto"
 	sshuserhash "github.com/netbirdio/netbird/shared/sshauth"
@@ -118,6 +120,7 @@ func (e *Engine) startVNCServer() error {
 	if serviceMode {
 		log.Info("VNC: running as system service, enabling service mode (per-session agent proxy)")
 	}
+	requireApproval := e.config.DisableVNCApproval == nil || !*e.config.DisableVNCApproval
 	srv := vncserver.New(vncserver.Config{
 		Capturer:        capturer,
 		Injector:        injector,
@@ -125,6 +128,8 @@ func (e *Engine) startVNCServer() error {
 		ServiceMode:     serviceMode,
 		SessionRecorder: sessionRecorder,
 		NetstackNet:     e.wgInterface.GetNet(),
+		RequireApproval: requireApproval,
+		Approver:        &vncApprover{broker: e.approvalBroker, statusRecorder: e.statusRecorder},
 	})
 
 	listenAddr := netip.AddrPortFrom(netbirdIP, vncInternalPort)
@@ -152,7 +157,6 @@ func (e *Engine) startVNCServer() error {
 	return nil
 }
 
-
 // updateVNCServerAuth updates VNC fine-grained access control from management.
 func (e *Engine) updateVNCServerAuth(vncAuth *mgmProto.VNCAuth) {
 	if vncAuth == nil || e.vncSrv == nil {
@@ -192,8 +196,9 @@ func (e *Engine) updateVNCServerAuth(vncAuth *mgmProto.VNCAuth) {
 			continue
 		}
 		sessionPubKeys = append(sessionPubKeys, sshauth.SessionPubKey{
-			PubKey:     pub,
-			UserIDHash: sshuserhash.UserIDHash(hash),
+			PubKey:      pub,
+			UserIDHash:  sshuserhash.UserIDHash(hash),
+			DisplayName: e.GetDisplayName(),
 		})
 	}
 
@@ -238,3 +243,52 @@ func (e *Engine) stopVNCServer() error {
 	}
 	return nil
 }
+
+// vncApprover adapts the generic approval.Broker for the VNC server.
+type vncApprover struct {
+	broker         *approval.Broker
+	statusRecorder *peer.Status
+}
+
+func (a *vncApprover) Request(ctx context.Context, info vncserver.ApprovalInfo) (vncserver.ApprovalDecision, error) {
+	// Resolve the source overlay IP to a peer FQDN for the prompt label.
+	if info.PeerName == "" && info.SourceIP != "" && a.statusRecorder != nil {
+		if fqdn, ok := a.statusRecorder.PeerByIP(info.SourceIP); ok {
+			info.PeerName = fqdn
+		}
+	}
+	subject := fmt.Sprintf("VNC connection from %s", displayPeer(info))
+	meta := map[string]string{
+		"peer_name":   info.PeerName,
+		"peer_pubkey": info.PeerPubKey,
+		"source_ip":   info.SourceIP,
+		"mode":        info.Mode,
+		"username":    info.Username,
+		"initiator":   info.Initiator,
+	}
+	d, err := a.broker.Request(ctx, approval.Prompt{
+		Kind:     approval.KindVNC,
+		Subject:  subject,
+		Metadata: meta,
+	})
+	if err != nil {
+		return vncserver.ApprovalDecision{}, err
+	}
+	return vncserver.ApprovalDecision{ViewOnly: d.ViewOnly}, nil
+}
+
+func displayPeer(info vncserver.ApprovalInfo) string {
+	if info.Initiator != "" {
+		return info.Initiator
+	}
+	if info.PeerName != "" {
+		return info.PeerName
+	}
+	if info.SourceIP != "" {
+		return info.SourceIP
+	}
+	if info.PeerPubKey != "" {
+		return info.PeerPubKey
+	}
+	return "unknown peer"
+}

client/internal/peer/status.go

@@ -1191,6 +1191,15 @@ func (d *Status) SubscribeToEvents() *EventSubscription {
 	}
 }
 
+// HasEventSubscribers reports whether any client is currently subscribed
+// to the daemon's SystemEvent stream. Used by the VNC approval broker to
+// fail closed when no UI is connected to prompt the user.
+func (d *Status) HasEventSubscribers() bool {
+	d.eventMux.Lock()
+	defer d.eventMux.Unlock()
+	return len(d.eventStreams) > 0
+}
+
 // UnsubscribeFromEvents removes an event subscription
 func (d *Status) UnsubscribeFromEvents(sub *EventSubscription) {
 	if sub == nil {

client/internal/profilemanager/config.go

@@ -66,6 +66,7 @@ type ConfigInput struct {
 	PreSharedKey                  *string
 	ServerSSHAllowed              *bool
 	ServerVNCAllowed              *bool
+	DisableVNCApproval            *bool
 	EnableSSHRoot                 *bool
 	EnableSSHSFTP                 *bool
 	EnableSSHLocalPortForwarding  *bool
@@ -118,6 +119,7 @@ type Config struct {
 	RosenpassPermissive           bool
 	ServerSSHAllowed              *bool
 	ServerVNCAllowed              *bool
+	DisableVNCApproval            *bool
 	EnableSSHRoot                 *bool
 	EnableSSHSFTP                 *bool
 	EnableSSHLocalPortForwarding  *bool
@@ -435,6 +437,18 @@ func (config *Config) apply(input ConfigInput) (updated bool, err error) {
 		updated = true
 	}
 
+	if input.DisableVNCApproval != nil {
+		if config.DisableVNCApproval == nil || *input.DisableVNCApproval != *config.DisableVNCApproval {
+			if *input.DisableVNCApproval {
+				log.Infof("disabling VNC connection approval prompt")
+			} else {
+				log.Infof("enabling VNC connection approval prompt")
+			}
+			config.DisableVNCApproval = input.DisableVNCApproval
+			updated = true
+		}
+	}
+
 	if input.EnableSSHRoot != nil && input.EnableSSHRoot != config.EnableSSHRoot {
 		if *input.EnableSSHRoot {
 			log.Infof("enabling SSH root login")