[management, client, proxy] add expose NetBird-only services over tunnel peers (#6226)

Adds a new "private" service mode for the reverse proxy: services reachable exclusively over the embedded WireGuard tunnel, gated by per-peer group membership instead of operator auth schemes.

Wire contract
- ProxyMapping.private (field 13): the proxy MUST call ValidateTunnelPeer and fail closed; operator schemes are bypassed.
- ProxyCapabilities.private (4) + supports_private_service (5): capability gate. Management never streams private mappings to proxies that don't claim the capability; the broadcast path applies the same filter via filterMappingsForProxy.
- ValidateTunnelPeer RPC: resolves an inbound tunnel IP to a peer, checks the peer's groups against service.AccessGroups, and mints a session JWT on success. checkPeerGroupAccess fails closed when a private service has empty AccessGroups.
- ValidateSession/ValidateTunnelPeer responses now carry peer_group_ids + peer_group_names so the proxy can authorise policy-aware middlewares without an extra management round-trip.
- ProxyInboundListener + SendStatusUpdate.inbound_listener: per-account inbound listener state surfaced to dashboards.
- PathTargetOptions.direct_upstream (11): bypass the embedded NetBird client and dial the target via the proxy host's network stack for upstreams reachable without WireGuard.

Data model
- Service.Private (bool) + Service.AccessGroups ([]string, JSON- serialised). Validate() rejects bearer auth on private services. Copy() deep-copies AccessGroups. pgx getServices loads the columns.
- DomainConfig.Private threaded into the proxy auth middleware. Request handler routes private services through forwardWithTunnelPeer and returns 403 on validation failure.
- Account-level SynthesizePrivateServiceZones (synthetic DNS) and injectPrivateServicePolicies (synthetic ACL) gate on len(svc.AccessGroups) > 0.

Proxy
- /netbird proxy --private (embedded mode) flag; Config.Private in proxy/lifecycle.go.
- Per-account inbound listener (proxy/inbound.go) binding HTTP/HTTPS on the embedded NetBird client's WireGuard tunnel netstack.
- proxy/internal/auth/tunnel_cache: ValidateTunnelPeer response cache with single-flight de-duplication and per-account eviction.
- Local peerstore short-circuit: when the inbound IP isn't in the account roster, deny fast without an RPC.
- proxy/server.go reports SupportsPrivateService=true and redacts the full ProxyMapping JSON from info logs (auth_token + header-auth hashed values now only at debug level).

Identity forwarding
- ValidateSessionJWT returns user_id, email, method, groups, group_names. sessionkey.Claims carries Email + Groups + GroupNames so the proxy can stamp identity onto upstream requests without an extra management round-trip on every cookie-bearing request.
- CapturedData carries userEmail / userGroups / userGroupNames; the proxy stamps X-NetBird-User and X-NetBird-Groups on r.Out from the authenticated identity (strips client-supplied values first to prevent spoofing).
- AccessLog.UserGroups: access-log enrichment captures the user's group memberships at write time so the dashboard can render group context without reverse-resolving stale memberships.

OpenAPI/dashboard surface
- ReverseProxyService gains private + access_groups; ReverseProxyCluster gains private + supports_private. ReverseProxyTarget target_type enum gains "cluster". ServiceTargetOptions gains direct_upstream. ProxyAccessLog gains user_groups.

management/internals/modules/reverseproxy/service/manager/api.go

@@ -204,6 +204,7 @@ func (h *handler) getClusters(w http.ResponseWriter, r *http.Request) {
 			SupportsCustomPorts: c.SupportsCustomPorts,
 			RequireSubdomain:    c.RequireSubdomain,
 			SupportsCrowdsec:    c.SupportsCrowdSec,
+			Private:             c.Private,
 		})
 	}
 

management/internals/modules/reverseproxy/service/manager/manager.go

@@ -82,6 +82,7 @@ type CapabilityProvider interface {
 	ClusterSupportsCustomPorts(ctx context.Context, clusterAddr string) *bool
 	ClusterRequireSubdomain(ctx context.Context, clusterAddr string) *bool
 	ClusterSupportsCrowdSec(ctx context.Context, clusterAddr string) *bool
+	ClusterSupportsPrivate(ctx context.Context, clusterAddr string) *bool
 }
 
 type Manager struct {
@@ -136,6 +137,7 @@ func (m *Manager) GetClusters(ctx context.Context, accountID, userID string) ([]
 		clusters[i].SupportsCustomPorts = m.capabilities.ClusterSupportsCustomPorts(ctx, clusters[i].Address)
 		clusters[i].RequireSubdomain = m.capabilities.ClusterRequireSubdomain(ctx, clusters[i].Address)
 		clusters[i].SupportsCrowdSec = m.capabilities.ClusterSupportsCrowdSec(ctx, clusters[i].Address)
+		clusters[i].Private = m.capabilities.ClusterSupportsPrivate(ctx, clusters[i].Address)
 	}
 
 	return clusters, nil
@@ -208,6 +210,9 @@ func (m *Manager) replaceHostByLookup(ctx context.Context, accountID string, s *
 			target.Host = resource.Domain
 		case service.TargetTypeSubnet:
 			// For subnets we do not do any lookups on the resource
+		case service.TargetTypeCluster:
+			// Cluster targets carry the upstream address on target_id; the
+			// proxy resolves the destination at request time.
 		default:
 			return fmt.Errorf("unknown target type: %s", target.TargetType)
 		}
@@ -779,6 +784,10 @@ func validateTargetReferences(ctx context.Context, transaction store.Store, acco
 			if err := validateResourceTarget(ctx, transaction, accountID, target); err != nil {
 				return err
 			}
+		case service.TargetTypeCluster:
+			if err := validateClusterTarget(target); err != nil {
+				return err
+			}
 		default:
 			return status.Errorf(status.InvalidArgument, "unknown target type %q for target %q", target.TargetType, target.TargetId)
 		}
@@ -786,6 +795,13 @@ func validateTargetReferences(ctx context.Context, transaction store.Store, acco
 	return nil
 }
 
+func validateClusterTarget(target *service.Target) error {
+	if !target.Options.DirectUpstream {
+		return status.Errorf(status.InvalidArgument, "cluster target %s has direct upstream disabled", target.Host)
+	}
+	return nil
+}
+
 func validatePeerTarget(ctx context.Context, transaction store.Store, accountID string, target *service.Target) error {
 	if _, err := transaction.GetPeerByID(ctx, store.LockingStrengthShare, accountID, target.TargetId); err != nil {
 		if sErr, ok := status.FromError(err); ok && sErr.Type() == status.NotFound {
@@ -962,12 +978,14 @@ func (m *Manager) ReloadAllServicesForAccount(ctx context.Context, accountID str
 		return fmt.Errorf("failed to get services: %w", err)
 	}
 
+	oidcCfg := m.proxyController.GetOIDCValidationConfig()
+
 	for _, s := range services {
 		err = m.replaceHostByLookup(ctx, accountID, s)
 		if err != nil {
 			return fmt.Errorf("failed to replace host by lookup for service %s: %w", s.ID, err)
 		}
-		m.proxyController.SendServiceUpdateToCluster(ctx, accountID, s.ToProtoMapping(service.Update, "", m.proxyController.GetOIDCValidationConfig()), s.ProxyCluster)
+		m.proxyController.SendServiceUpdateToCluster(ctx, accountID, s.ToProtoMapping(service.Update, "", oidcCfg), s.ProxyCluster)
 	}
 
 	return nil

management/internals/modules/reverseproxy/service/manager/manager_test.go

@@ -1344,3 +1344,66 @@ func TestValidateSubdomainRequirement(t *testing.T) {
 		})
 	}
 }
+
+func TestValidateTargetReferences_ClusterTargetSkipsLookup(t *testing.T) {
+	ctx := context.Background()
+	ctrl := gomock.NewController(t)
+	mockStore := store.NewMockStore(ctrl)
+	accountID := "test-account"
+
+	// No peer or resource lookups must be issued for cluster targets.
+	targets := []*rpservice.Target{
+		{
+			TargetId:   "eu.proxy.netbird.io",
+			TargetType: rpservice.TargetTypeCluster,
+			Options:    rpservice.TargetOptions{DirectUpstream: true},
+		},
+	}
+	require.NoError(t, validateTargetReferences(ctx, mockStore, accountID, targets), "cluster target must validate without store lookups")
+}
+
+// TestValidateTargetReferences_ClusterTargetRequiresDirectUpstream pins the
+// store-side check that cluster targets must opt into the host-stack dial
+// path. Without DirectUpstream the proxy would route this target through
+// the embedded NetBird client and fail on every request.
+func TestValidateTargetReferences_ClusterTargetRequiresDirectUpstream(t *testing.T) {
+	ctx := context.Background()
+	ctrl := gomock.NewController(t)
+	mockStore := store.NewMockStore(ctrl)
+	accountID := "test-account"
+
+	targets := []*rpservice.Target{
+		{
+			TargetId:   "eu.proxy.netbird.io",
+			TargetType: rpservice.TargetTypeCluster,
+			Host:       "backend.lan",
+		},
+	}
+	err := validateTargetReferences(ctx, mockStore, accountID, targets)
+	require.Error(t, err, "cluster target without direct_upstream must be rejected")
+	assert.ErrorContains(t, err, "direct upstream disabled")
+}
+
+func TestReplaceHostByLookup_SkipsClusterTarget(t *testing.T) {
+	ctx := context.Background()
+	ctrl := gomock.NewController(t)
+	mockStore := store.NewMockStore(ctrl)
+	accountID := "test-account"
+
+	mgr := &Manager{store: mockStore}
+
+	svc := &rpservice.Service{
+		ID:        "svc-1",
+		AccountID: accountID,
+		Targets: []*rpservice.Target{
+			{
+				TargetId:   "eu.proxy.netbird.io",
+				TargetType: rpservice.TargetTypeCluster,
+				Host:       "127.0.0.1",
+			},
+		},
+	}
+
+	require.NoError(t, mgr.replaceHostByLookup(ctx, accountID, svc), "cluster target must not trigger peer/resource lookup")
+	assert.Equal(t, "127.0.0.1", svc.Targets[0].Host, "operator-supplied host must be preserved for cluster target")
+}

management/internals/modules/reverseproxy/service/service.go

@@ -45,10 +45,11 @@ const (
 	StatusCertificateFailed  Status = "certificate_failed"
 	StatusError              Status = "error"
 
-	TargetTypePeer   TargetType = "peer"
-	TargetTypeHost   TargetType = "host"
-	TargetTypeDomain TargetType = "domain"
-	TargetTypeSubnet TargetType = "subnet"
+	TargetTypePeer    TargetType = "peer"
+	TargetTypeHost    TargetType = "host"
+	TargetTypeDomain  TargetType = "domain"
+	TargetTypeSubnet  TargetType = "subnet"
+	TargetTypeCluster TargetType = "cluster"
 
 	SourcePermanent = "permanent"
 	SourceEphemeral = "ephemeral"
@@ -60,6 +61,11 @@ type TargetOptions struct {
 	SessionIdleTimeout time.Duration     `json:"session_idle_timeout,omitempty"`
 	PathRewrite        PathRewriteMode   `json:"path_rewrite,omitempty"`
 	CustomHeaders      map[string]string `gorm:"serializer:json" json:"custom_headers,omitempty"`
+	// DirectUpstream bypasses the proxy's embedded NetBird client and dials
+	// the target via the proxy host's network stack. Useful for upstreams
+	// reachable without WireGuard (public APIs, LAN services, localhost
+	// sidecars). Default false.
+	DirectUpstream bool `json:"direct_upstream,omitempty"`
 }
 
 type Target struct {
@@ -67,7 +73,7 @@ type Target struct {
 	AccountID     string        `gorm:"index:idx_target_account;not null" json:"-"`
 	ServiceID     string        `gorm:"index:idx_service_targets;not null" json:"-"`
 	Path          *string       `json:"path,omitempty"`
-	Host          string        `json:"host"` // the Host field is only used for subnet targets, otherwise ignored
+	Host          string        `json:"host"`
 	Port          uint16        `gorm:"index:idx_target_port" json:"port"`
 	Protocol      string        `gorm:"index:idx_target_protocol" json:"protocol"`
 	TargetId      string        `gorm:"index:idx_target_id" json:"target_id"`
@@ -200,6 +206,10 @@ type Service struct {
 	Mode             string `gorm:"default:'http'"`
 	ListenPort       uint16
 	PortAutoAssigned bool
+	// Private marks the service as NetBird-only: auth via ValidateTunnelPeer against AccessGroups instead of SSO. HTTP-only.
+	Private bool
+	// AccessGroups is the group ID allowlist for inbound peers on private services. Mutually exclusive with bearer SSO.
+	AccessGroups []string `json:"access_groups,omitempty" gorm:"serializer:json"`
 }
 
 // InitNewRecord generates a new unique ID and resets metadata for a newly created
@@ -299,6 +309,12 @@ func (s *Service) ToAPIResponse() *api.Service {
 		Mode:               &mode,
 		ListenPort:         &listenPort,
 		PortAutoAssigned:   &s.PortAutoAssigned,
+		Private:            &s.Private,
+	}
+
+	if len(s.AccessGroups) > 0 {
+		groups := append([]string(nil), s.AccessGroups...)
+		resp.AccessGroups = &groups
 	}
 
 	if s.ProxyCluster != "" {
@@ -308,6 +324,7 @@ func (s *Service) ToAPIResponse() *api.Service {
 	return resp
 }
 
+// ToProtoMapping converts the service into the wire format the proxy consumes.
 func (s *Service) ToProtoMapping(operation Operation, authToken string, oidcConfig proxy.OIDCValidationConfig) *proto.ProxyMapping {
 	pathMappings := s.buildPathMappings()
 
@@ -349,6 +366,7 @@ func (s *Service) ToProtoMapping(operation Operation, authToken string, oidcConf
 		RewriteRedirects: s.RewriteRedirects,
 		Mode:             s.Mode,
 		ListenPort:       int32(s.ListenPort), //nolint:gosec
+		Private:          s.Private,
 	}
 
 	if r := restrictionsToProto(s.Restrictions); r != nil {
@@ -455,7 +473,8 @@ func pathRewriteToProto(mode PathRewriteMode) proto.PathRewriteMode {
 }
 
 func targetOptionsToAPI(opts TargetOptions) *api.ServiceTargetOptions {
-	if !opts.SkipTLSVerify && opts.RequestTimeout == 0 && opts.SessionIdleTimeout == 0 && opts.PathRewrite == "" && len(opts.CustomHeaders) == 0 {
+	if !opts.SkipTLSVerify && opts.RequestTimeout == 0 && opts.SessionIdleTimeout == 0 &&
+		opts.PathRewrite == "" && len(opts.CustomHeaders) == 0 && !opts.DirectUpstream {
 		return nil
 	}
 	apiOpts := &api.ServiceTargetOptions{}
@@ -477,17 +496,22 @@ func targetOptionsToAPI(opts TargetOptions) *api.ServiceTargetOptions {
 	if len(opts.CustomHeaders) > 0 {
 		apiOpts.CustomHeaders = &opts.CustomHeaders
 	}
+	if opts.DirectUpstream {
+		apiOpts.DirectUpstream = &opts.DirectUpstream
+	}
 	return apiOpts
 }
 
 func targetOptionsToProto(opts TargetOptions) *proto.PathTargetOptions {
-	if !opts.SkipTLSVerify && opts.PathRewrite == "" && opts.RequestTimeout == 0 && len(opts.CustomHeaders) == 0 {
+	if !opts.SkipTLSVerify && opts.PathRewrite == "" && opts.RequestTimeout == 0 &&
+		len(opts.CustomHeaders) == 0 && !opts.DirectUpstream {
 		return nil
 	}
 	popts := &proto.PathTargetOptions{
-		SkipTlsVerify: opts.SkipTLSVerify,
-		PathRewrite:   pathRewriteToProto(opts.PathRewrite),
-		CustomHeaders: opts.CustomHeaders,
+		SkipTlsVerify:  opts.SkipTLSVerify,
+		PathRewrite:    pathRewriteToProto(opts.PathRewrite),
+		CustomHeaders:  opts.CustomHeaders,
+		DirectUpstream: opts.DirectUpstream,
 	}
 	if opts.RequestTimeout != 0 {
 		popts.RequestTimeout = durationpb.New(opts.RequestTimeout)
@@ -537,6 +561,9 @@ func targetOptionsFromAPI(idx int, o *api.ServiceTargetOptions) (TargetOptions,
 	if o.CustomHeaders != nil {
 		opts.CustomHeaders = *o.CustomHeaders
 	}
+	if o.DirectUpstream != nil {
+		opts.DirectUpstream = *o.DirectUpstream
+	}
 	return opts, nil
 }
 
@@ -551,6 +578,14 @@ func (s *Service) FromAPIRequest(req *api.ServiceRequest, accountID string) erro
 	if req.ListenPort != nil {
 		s.ListenPort = uint16(*req.ListenPort) //nolint:gosec
 	}
+	if req.Private != nil {
+		s.Private = *req.Private
+	}
+	if req.AccessGroups != nil {
+		s.AccessGroups = append([]string(nil), *req.AccessGroups...)
+	} else {
+		s.AccessGroups = nil
+	}
 
 	targets, err := targetsFromAPI(accountID, req.Targets)
 	if err != nil {
@@ -740,6 +775,9 @@ func (s *Service) Validate() error {
 	if err := validateAccessRestrictions(&s.Restrictions); err != nil {
 		return err
 	}
+	if err := s.validatePrivateRequirements(); err != nil {
+		return err
+	}
 
 	switch s.Mode {
 	case ModeHTTP:
@@ -753,6 +791,23 @@ func (s *Service) Validate() error {
 	}
 }
 
+// validatePrivateRequirements enforces the private-service contract: HTTP mode, ≥1 access group, no bearer auth.
+func (s *Service) validatePrivateRequirements() error {
+	if !s.Private {
+		return nil
+	}
+	if s.Mode != "" && s.Mode != ModeHTTP {
+		return fmt.Errorf("private services only support HTTP mode, got %q", s.Mode)
+	}
+	if len(s.AccessGroups) == 0 {
+		return errors.New("private services require at least one access group")
+	}
+	if s.Auth.BearerAuth != nil && s.Auth.BearerAuth.Enabled {
+		return errors.New("private services cannot enable bearer auth (SSO): NetBird-only access and SSO are mutually exclusive")
+	}
+	return nil
+}
+
 func (s *Service) validateHTTPMode() error {
 	if s.Domain == "" {
 		return errors.New("service domain is required")
@@ -799,11 +854,21 @@ func (s *Service) validateHTTPTargets() error {
 	for i, target := range s.Targets {
 		switch target.TargetType {
 		case TargetTypePeer, TargetTypeHost, TargetTypeDomain:
-			// host field will be ignored
+			// Host is normally overwritten by replaceHostByLookup with the
+			// resolved peer IP / resource address; operator-supplied values
+			// are honored only when DirectUpstream is set. Validate the
+			// override here so misconfigured hosts fail fast at API time.
+			if err := validateDirectUpstreamHost(i, target); err != nil {
+				return err
+			}
 		case TargetTypeSubnet:
 			if target.Host == "" {
 				return fmt.Errorf("target %d has empty host but target_type is %q", i, target.TargetType)
 			}
+		case TargetTypeCluster:
+			if err := validateClusterTarget(i, target); err != nil {
+				return err
+			}
 		default:
 			return fmt.Errorf("target %d has invalid target_type %q", i, target.TargetType)
 		}
@@ -821,25 +886,67 @@ func (s *Service) validateHTTPTargets() error {
 	return nil
 }
 
+// validateClusterTarget cluster targets should not have empty hosts and should have direct upstream enabled.
+func validateClusterTarget(idx int, target *Target) error {
+	host := strings.TrimSpace(target.Host)
+	if host == "" {
+		return fmt.Errorf("target %d: has empty host", idx)
+	}
+	if !target.Options.DirectUpstream {
+		return fmt.Errorf("target %d: %s has direct upstream disabled", idx, target.Host)
+	}
+	return validateDirectUpstreamHost(idx, target)
+}
+
+// validateDirectUpstreamHost validates the operator-supplied Host on a
+// peer/host/domain target when DirectUpstream is set. Empty Host is
+// allowed — the lookup fills in the default peer IP / resource address.
+// Without DirectUpstream the Host value is silently overwritten by
+// replaceHostByLookup, so we don't validate it (preserves the historical
+// behaviour where APIs accepted any value and dropped it). Non-empty
+// Host with DirectUpstream must look like a hostname or IP and must
+// not carry a port (port lives on Target.Port).
+func validateDirectUpstreamHost(idx int, target *Target) error {
+	if !target.Options.DirectUpstream {
+		return nil
+	}
+	host := strings.TrimSpace(target.Host)
+	if host == "" {
+		return nil
+	}
+	if strings.ContainsAny(host, " \t/") {
+		return fmt.Errorf("target %d: host %q contains invalid characters", idx, host)
+	}
+	if _, _, err := net.SplitHostPort(host); err == nil {
+		return fmt.Errorf("target %d: host %q must not include a port (set target.port instead)", idx, host)
+	}
+	return nil
+}
+
 func (s *Service) validateL4Target(target *Target) error {
 	// L4 services have a single target; per-target disable is meaningless
 	// (use the service-level Enabled flag instead). Force it on so that
 	// buildPathMappings always includes the target in the proto.
 	target.Enabled = true
 
-	if target.Port == 0 {
-		return errors.New("target port is required for L4 services")
-	}
 	if target.TargetId == "" {
 		return errors.New("target_id is required for L4 services")
 	}
+	if target.TargetType != TargetTypeCluster && target.Port == 0 {
+		return errors.New("target port is required for L4 services")
+	}
 	switch target.TargetType {
 	case TargetTypePeer, TargetTypeHost, TargetTypeDomain:
-		// OK
+		if err := validateDirectUpstreamHost(0, target); err != nil {
+			return err
+		}
 	case TargetTypeSubnet:
 		if target.Host == "" {
 			return errors.New("target host is required for subnet targets")
 		}
+	case TargetTypeCluster:
+		// target_id carries the cluster address; the proxy resolves
+		// the upstream at request time.
 	default:
 		return fmt.Errorf("invalid target_type %q for L4 service", target.TargetType)
 	}
@@ -1174,6 +1281,11 @@ func (s *Service) Copy() *Service {
 		}
 	}
 
+	var accessGroups []string
+	if len(s.AccessGroups) > 0 {
+		accessGroups = append([]string(nil), s.AccessGroups...)
+	}
+
 	return &Service{
 		ID:                s.ID,
 		AccountID:         s.AccountID,
@@ -1195,6 +1307,8 @@ func (s *Service) Copy() *Service {
 		Mode:              s.Mode,
 		ListenPort:        s.ListenPort,
 		PortAutoAssigned:  s.PortAutoAssigned,
+		Private:           s.Private,
+		AccessGroups:      accessGroups,
 	}
 }
 

management/internals/modules/reverseproxy/service/service_test.go

@@ -12,6 +12,7 @@ import (
 
 	"github.com/netbirdio/netbird/management/internals/modules/reverseproxy/proxy"
 	"github.com/netbirdio/netbird/shared/hash/argon2id"
+	"github.com/netbirdio/netbird/shared/management/http/api"
 	"github.com/netbirdio/netbird/shared/management/proto"
 )
 
@@ -1116,3 +1117,191 @@ func TestValidate_HeaderAuths(t *testing.T) {
 		assert.Contains(t, err.Error(), "exceeds maximum length")
 	})
 }
+
+func TestValidate_HTTPClusterTarget(t *testing.T) {
+	rp := validProxy()
+	rp.Targets = []*Target{{
+		TargetId:   "eu.proxy.netbird.io",
+		TargetType: TargetTypeCluster,
+		Protocol:   "http",
+		Host:       "backend.lan",
+		Options:    TargetOptions{DirectUpstream: true},
+		Enabled:    true,
+	}}
+	require.NoError(t, rp.Validate(), "HTTP cluster target with target_id, host, and direct_upstream must validate")
+}
+
+func TestValidate_HTTPClusterTarget_RequiresTargetId(t *testing.T) {
+	rp := validProxy()
+	rp.Targets = []*Target{{
+		TargetType: TargetTypeCluster,
+		Protocol:   "http",
+		Host:       "backend.lan",
+		Options:    TargetOptions{DirectUpstream: true},
+		Enabled:    true,
+	}}
+	assert.ErrorContains(t, rp.Validate(), "empty target_id", "cluster target must reject empty target_id")
+}
+
+// TestValidate_HTTPClusterTarget_RequiresHost pins the new cluster-target
+// rule that operator-supplied Host is mandatory: cluster targets dial the
+// upstream via the host network stack (direct_upstream is implied), so an
+// empty Host leaves the proxy with nothing to dial.
+func TestValidate_HTTPClusterTarget_RequiresHost(t *testing.T) {
+	rp := validProxy()
+	rp.Targets = []*Target{{
+		TargetId:   "eu.proxy.netbird.io",
+		TargetType: TargetTypeCluster,
+		Protocol:   "http",
+		Options:    TargetOptions{DirectUpstream: true},
+		Enabled:    true,
+	}}
+	assert.ErrorContains(t, rp.Validate(), "empty host", "cluster target must reject empty host")
+}
+
+// TestValidate_HTTPClusterTarget_RequiresDirectUpstream pins the second
+// half of the cluster-target rule: DirectUpstream must be true so the
+// stdlib transport branch in MultiTransport is taken. Without it the
+// embedded NetBird client would try to dial the cluster address through
+// the WG tunnel, which is the wrong network for a cluster upstream.
+func TestValidate_HTTPClusterTarget_RequiresDirectUpstream(t *testing.T) {
+	rp := validProxy()
+	rp.Targets = []*Target{{
+		TargetId:   "eu.proxy.netbird.io",
+		TargetType: TargetTypeCluster,
+		Protocol:   "http",
+		Host:       "backend.lan",
+		Enabled:    true,
+	}}
+	assert.ErrorContains(t, rp.Validate(), "direct upstream disabled", "cluster target must reject direct_upstream=false")
+}
+
+func TestValidate_L4ClusterTarget(t *testing.T) {
+	rp := validProxy()
+	rp.Mode = ModeTCP
+	rp.ListenPort = 9000
+	rp.Targets = []*Target{{
+		TargetId:   "eu.proxy.netbird.io",
+		TargetType: TargetTypeCluster,
+		Protocol:   "tcp",
+		Enabled:    true,
+	}}
+	require.NoError(t, rp.Validate(), "L4 cluster target must validate without an explicit port")
+}
+
+func TestService_Copy_RoundtripsPrivate(t *testing.T) {
+	svc := validProxy()
+	svc.Private = true
+	svc.AccessGroups = []string{"grp-admins", "grp-ops"}
+	cp := svc.Copy()
+	require.NotNil(t, cp)
+	assert.True(t, cp.Private)
+	assert.Equal(t, []string{"grp-admins", "grp-ops"}, cp.AccessGroups)
+
+	cp.Private = false
+	assert.True(t, svc.Private)
+
+	cp.AccessGroups[0] = "grp-other"
+	assert.Equal(t, []string{"grp-admins", "grp-ops"}, svc.AccessGroups)
+}
+
+func TestService_APIRoundtrip_Private(t *testing.T) {
+	enabled := true
+	private := true
+	accessGroups := []string{"grp-admins"}
+	targets := []api.ServiceTarget{{
+		TargetId:   "eu.proxy.netbird.io",
+		TargetType: api.ServiceTargetTargetType("cluster"),
+		Protocol:   "http",
+		Port:       80,
+		Enabled:    true,
+	}}
+	req := &api.ServiceRequest{
+		Name:         "svc-private",
+		Domain:       "myapp.eu.proxy.netbird.io",
+		Enabled:      enabled,
+		Private:      &private,
+		AccessGroups: &accessGroups,
+		Targets:      &targets,
+	}
+
+	svc := &Service{}
+	require.NoError(t, svc.FromAPIRequest(req, "acc-1"))
+	assert.True(t, svc.Private)
+	assert.Equal(t, []string{"grp-admins"}, svc.AccessGroups)
+
+	resp := svc.ToAPIResponse()
+	require.NotNil(t, resp.Private)
+	assert.True(t, *resp.Private)
+	require.NotNil(t, resp.AccessGroups)
+	assert.Equal(t, []string{"grp-admins"}, *resp.AccessGroups)
+}
+
+func TestValidate_Private_RequiresAccessGroups(t *testing.T) {
+	rp := validProxy()
+	rp.Private = true
+	rp.Targets = []*Target{{
+		TargetId:   "eu.proxy.netbird.io",
+		TargetType: TargetTypeCluster,
+		Protocol:   "http",
+		Host:       "backend.lan",
+		Options:    TargetOptions{DirectUpstream: true},
+		Enabled:    true,
+	}}
+	assert.ErrorContains(t, rp.Validate(), "access group")
+}
+
+func TestValidate_Private_RejectsBearerAuth(t *testing.T) {
+	rp := validProxy()
+	rp.Private = true
+	rp.AccessGroups = []string{"grp-admins"}
+	rp.Auth.BearerAuth = &BearerAuthConfig{
+		Enabled:            true,
+		DistributionGroups: []string{"grp-sso"},
+	}
+	rp.Targets = []*Target{{
+		TargetId:   "eu.proxy.netbird.io",
+		TargetType: TargetTypeCluster,
+		Protocol:   "http",
+		Host:       "backend.lan",
+		Options:    TargetOptions{DirectUpstream: true},
+		Enabled:    true,
+	}}
+	assert.ErrorContains(t, rp.Validate(), "mutually exclusive")
+}
+
+func TestValidate_Private_AcceptsNonClusterTargets(t *testing.T) {
+	rp := validProxy()
+	rp.Private = true
+	rp.AccessGroups = []string{"grp-admins"}
+	require.NoError(t, rp.Validate())
+}
+
+func TestValidate_Private_AcceptsClusterTargetWithAccessGroups(t *testing.T) {
+	rp := validProxy()
+	rp.Private = true
+	rp.AccessGroups = []string{"grp-admins"}
+	rp.Targets = []*Target{{
+		TargetId:   "eu.proxy.netbird.io",
+		TargetType: TargetTypeCluster,
+		Protocol:   "http",
+		Host:       "backend.lan",
+		Options:    TargetOptions{DirectUpstream: true},
+		Enabled:    true,
+	}}
+	require.NoError(t, rp.Validate())
+}
+
+func TestValidate_Private_RejectsNonHTTPMode(t *testing.T) {
+	rp := validProxy()
+	rp.Private = true
+	rp.AccessGroups = []string{"grp-admins"}
+	rp.Mode = ModeTCP
+	rp.Targets = []*Target{{
+		TargetId:   "eu.proxy.netbird.io",
+		TargetType: TargetTypeCluster,
+		Protocol:   "tcp",
+		Enabled:    true,
+	}}
+	assert.ErrorContains(t, rp.Validate(), "HTTP")
+}