diff --git a/net/tstun/wrap.go b/net/tstun/wrap.go
index d463948a2..3c1315437 100644
--- a/net/tstun/wrap.go
+++ b/net/tstun/wrap.go
@@ -171,6 +171,9 @@ type Wrapper struct {
 	// PreFilterPacketInboundFromWireGuard is the inbound filter function that runs before the main filter
 	// and therefore sees the packets that may be later dropped by it.
 	PreFilterPacketInboundFromWireGuard FilterFunc
+	// PostFilterPacketInboundFromWireGuardAppConnector runs after the filter, but before PostFilterPacketInboundFromWireGuard.
+	// Non-app connector traffic is passed along. Invalid app connector traffic is dropped.
+	PostFilterPacketInboundFromWireGuardAppConnector FilterFunc
 	// PostFilterPacketInboundFromWireGuard is the inbound filter function that runs after the main filter.
 	PostFilterPacketInboundFromWireGuard GROFilterFunc
 	// PreFilterPacketOutboundToWireGuardNetstackIntercept is a filter function that runs before the main filter
@@ -183,6 +186,10 @@ type Wrapper struct {
 	// packets which it handles internally. If both this and PreFilterFromTunToNetstack
 	// filter functions are non-nil, this filter runs second.
 	PreFilterPacketOutboundToWireGuardEngineIntercept FilterFunc
+	// PreFilterPacketOutboundToWireGuardAppConnectorIntercept runs after PreFilterPacketOutboundToWireGuardEngineIntercept
+	// for app connector specific traffic. Non-app connector traffic is passed along. Invalid app connector traffic is
+	// dropped.
+	PreFilterPacketOutboundToWireGuardAppConnectorIntercept FilterFunc
 	// PostFilterPacketOutboundToWireGuard is the outbound filter function that runs after the main filter.
 	PostFilterPacketOutboundToWireGuard FilterFunc
 
@@ -872,6 +879,12 @@ func (t *Wrapper) filterPacketOutboundToWireGuard(p *packet.Parsed, pc *peerConf
 			return res, gro
 		}
 	}
+	if t.PreFilterPacketOutboundToWireGuardAppConnectorIntercept != nil {
+		if res := t.PreFilterPacketOutboundToWireGuardAppConnectorIntercept(p, t); res.IsDrop() {
+			// Handled by userspaceEngine's configured hook for Connectors 2025 app connectors.
+			return res, gro
+		}
+	}
 
 	// If the outbound packet is to a jailed peer, use our jailed peer
 	// packet filter.
@@ -1234,6 +1247,13 @@ func (t *Wrapper) filterPacketInboundFromWireGuard(p *packet.Parsed, captHook pa
 		return filter.Drop, gro
 	}
 
+	if t.PostFilterPacketInboundFromWireGuardAppConnector != nil {
+		if res := t.PostFilterPacketInboundFromWireGuardAppConnector(p, t); res.IsDrop() {
+			// Handled by userspaceEngine's configured hook for Connectors 2025 app connectors.
+			return res, gro
+		}
+	}
+
 	if t.PostFilterPacketInboundFromWireGuard != nil {
 		var res filter.Response
 		res, gro = t.PostFilterPacketInboundFromWireGuard(p, t, gro)
diff --git a/wgengine/userspace.go b/wgengine/userspace.go
index e69712061..245ce421f 100644
--- a/wgengine/userspace.go
+++ b/wgengine/userspace.go
@@ -143,8 +143,9 @@ type userspaceEngine struct {
 	trimmedNodes        map[key.NodePublic]bool   // set of node keys of peers currently excluded from wireguard config
 	sentActivityAt      map[netip.Addr]*mono.Time // value is accessed atomically
 	destIPActivityFuncs map[netip.Addr]func()
-	lastStatusPollTime  mono.Time    // last time we polled the engine status
-	reconfigureVPN      func() error // or nil
+	lastStatusPollTime  mono.Time         // last time we polled the engine status
+	reconfigureVPN      func() error      // or nil
+	conn25PacketHooks   Conn25PacketHooks // or nil
 
 	mu             sync.Mutex         // guards following; see lock order comment below
 	netMap         *netmap.NetworkMap // or nil
@@ -175,6 +176,19 @@ type BIRDClient interface {
 	Close() error
 }
 
+// Conn25PacketHooks are hooks for Connectors 2025 app connectors.
+// They are meant to be wired into to corresponding hooks in the
+// [tstun.Wrapper]. They may modify the packet (e.g., NAT), or drop
+// invalid app connector traffic.
+type Conn25PacketHooks interface {
+	// HandlePacketsFromTunDevice sends packets originating from the tun device
+	// for further Connectors 2025 app connectors processing.
+	HandlePacketsFromTunDevice(*packet.Parsed) filter.Response
+	// HandlePacketsFromWireguard sends packets originating from WireGuard
+	// for further Connectors 2025 app connectors processing.
+	HandlePacketsFromWireGuard(*packet.Parsed) filter.Response
+}
+
 // Config is the engine configuration.
 type Config struct {
 	// Tun is the device used by the Engine to exchange packets with
@@ -247,6 +261,10 @@ type Config struct {
 	// TODO(creachadair): As of 2025-03-19 this is optional, but is intended to
 	// become required non-nil.
 	EventBus *eventbus.Bus
+
+	// Conn25PacketHooks, if non-nil, is used to hook packets for Connectors 2025
+	// app connector handling logic.
+	Conn25PacketHooks Conn25PacketHooks
 }
 
 // NewFakeUserspaceEngine returns a new userspace engine for testing.
@@ -348,19 +366,20 @@ func NewUserspaceEngine(logf logger.Logf, conf Config) (_ Engine, reterr error)
 	}
 
 	e := &userspaceEngine{
-		eventBus:       conf.EventBus,
-		timeNow:        mono.Now,
-		logf:           logf,
-		reqCh:          make(chan struct{}, 1),
-		waitCh:         make(chan struct{}),
-		tundev:         tsTUNDev,
-		router:         rtr,
-		dialer:         conf.Dialer,
-		confListenPort: conf.ListenPort,
-		birdClient:     conf.BIRDClient,
-		controlKnobs:   conf.ControlKnobs,
-		reconfigureVPN: conf.ReconfigureVPN,
-		health:         conf.HealthTracker,
+		eventBus:          conf.EventBus,
+		timeNow:           mono.Now,
+		logf:              logf,
+		reqCh:             make(chan struct{}, 1),
+		waitCh:            make(chan struct{}),
+		tundev:            tsTUNDev,
+		router:            rtr,
+		dialer:            conf.Dialer,
+		confListenPort:    conf.ListenPort,
+		birdClient:        conf.BIRDClient,
+		controlKnobs:      conf.ControlKnobs,
+		reconfigureVPN:    conf.ReconfigureVPN,
+		health:            conf.HealthTracker,
+		conn25PacketHooks: conf.Conn25PacketHooks,
 	}
 
 	if e.birdClient != nil {
@@ -434,6 +453,16 @@ func NewUserspaceEngine(logf logger.Logf, conf Config) (_ Engine, reterr error)
 	}
 	e.tundev.PreFilterPacketOutboundToWireGuardEngineIntercept = e.handleLocalPackets
 
+	if e.conn25PacketHooks != nil {
+		e.tundev.PreFilterPacketOutboundToWireGuardAppConnectorIntercept = func(p *packet.Parsed, _ *tstun.Wrapper) filter.Response {
+			return e.conn25PacketHooks.HandlePacketsFromTunDevice(p)
+		}
+
+		e.tundev.PostFilterPacketInboundFromWireGuardAppConnector = func(p *packet.Parsed, _ *tstun.Wrapper) filter.Response {
+			return e.conn25PacketHooks.HandlePacketsFromWireGuard(p)
+		}
+	}
+
 	if buildfeatures.HasDebug && envknob.BoolDefaultTrue("TS_DEBUG_CONNECT_FAILURES") {
 		if e.tundev.PreFilterPacketInboundFromWireGuard != nil {
 			return nil, errors.New("unexpected PreFilterIn already set")