wakey wakey

Fix a test race, make dns server reload/restart safer (#1815 )
Bump the golang-x-dependencies group across 1 directory with 5 updates (#1800 )
2026-08-15 17:56:58 +02:00 · 2026-07-22 18:49:19 -05:00 · 2026-07-22 15:05:10 -05:00 · 2026-07-22 15:51:22 -04:00 · 2026-07-22 15:49:45 -04:00 · 2026-07-21 19:32:33 -04:00
29 changed files with 1275 additions and 271 deletions
@@ -25,9 +25,9 @@ inputs:
    required: false
    default: "code-signer"
  key-prefix:
-    description: "S3 key prefix the caller is authorized to write under"
+    description: "S3 key prefix to write under; defaults to code-signing/<owner>/<repo> of the calling repo"
    required: false
-    default: "code-signing/slackhq/nebula"
+    default: ""

 runs:
  using: composite
@@ -57,6 +57,9 @@ runs:
        KEY_PREFIX: ${{ inputs.key-prefix }}
      run: |
        set -eu
+        # Default the prefix to this repo so the S3 key attributes the sign correctly.
+        # nebula-nightly runs this same action but writes under its own repo's prefix.
+        KEY_PREFIX="${KEY_PREFIX:-code-signing/$GITHUB_REPOSITORY}"
        RUN="${GITHUB_RUN_ID}-${GITHUB_RUN_ATTEMPT}"

        find "$SIGN_PATH" -name '*.exe' -print | while read -r path
@@ -12,7 +12,7 @@ jobs:
    steps:
      - uses: actions/checkout@v7

-      - uses: actions/setup-go@v6
+      - uses: actions/setup-go@v7
        with:
          go-version: '1.25'
          check-latest: true
@@ -38,7 +38,7 @@ jobs:
    steps:
      - uses: actions/checkout@v7

-      - uses: actions/setup-go@v6
+      - uses: actions/setup-go@v7
        with:
          go-version: '1.25'
          check-latest: true
@@ -78,7 +78,7 @@ jobs:
    steps:
      - uses: actions/checkout@v7

-      - uses: actions/setup-go@v6
+      - uses: actions/setup-go@v7
        with:
          go-version: '1.25'
          check-latest: true
@@ -32,7 +32,7 @@ jobs:

    - uses: actions/checkout@v7

-    - uses: actions/setup-go@v6
+    - uses: actions/setup-go@v7
      with:
        go-version: '1.25'
        check-latest: true
@@ -64,7 +64,7 @@ jobs:

    - uses: actions/checkout@v7

-    - uses: actions/setup-go@v6
+    - uses: actions/setup-go@v7
      with:
        go-version: '1.25'
        check-latest: true
@@ -90,7 +90,7 @@ jobs:

    - uses: actions/checkout@v7

-    - uses: actions/setup-go@v6
+    - uses: actions/setup-go@v7
      with:
        go-version: '1.25'
        check-latest: true
@@ -20,7 +20,7 @@ jobs:

    - uses: actions/checkout@v7

-    - uses: actions/setup-go@v6
+    - uses: actions/setup-go@v7
      with:
        go-version: '1.25'
        check-latest: true
@@ -20,7 +20,7 @@ jobs:

    - uses: actions/checkout@v7

-    - uses: actions/setup-go@v6
+    - uses: actions/setup-go@v7
      with:
        go-version: '1.25'
        check-latest: true
@@ -80,7 +80,7 @@ jobs:

    - uses: actions/checkout@v7

-    - uses: actions/setup-go@v6
+    - uses: actions/setup-go@v7
      with:
        go-version: '1.25'
        check-latest: true
@@ -125,7 +125,7 @@ jobs:

    - uses: actions/checkout@v7

-    - uses: actions/setup-go@v6
+    - uses: actions/setup-go@v7
      with:
        go-version: '1.25'
        check-latest: true
@@ -0,0 +1,96 @@
+//go:build linux && !android && !e2e_testing
+
+package main
+
+import (
+	"fmt"
+	"net/netip"
+	"os"
+	"path/filepath"
+	"runtime"
+	"testing"
+	"time"
+
+	"github.com/slackhq/nebula"
+	"github.com/slackhq/nebula/cert"
+	cert_test "github.com/slackhq/nebula/cert_test"
+	"github.com/slackhq/nebula/config"
+	"github.com/slackhq/nebula/test"
+	"github.com/stretchr/testify/require"
+)
+
+// TestControlStopClosesOnTimer reproduces the dnclient lifecycle: nebula runs as
+// a library, and on a config update dnclient calls Stop() in-process to tear the
+// old instance down before starting a new one. This boots a real nebula (real
+// blocking UDP sockets, tun disabled), lets it run, then Stop()s it on a timer
+// and asserts it actually closes. If the reader goroutines parked in recvmmsg
+// don't wake on Close(), Wait() blocks forever and this fails with a goroutine
+// dump instead of relying on a process signal to unstick them.
+func TestControlStopClosesOnTimer(t *testing.T) {
+	l := test.NewLogger()
+	dir := t.TempDir()
+
+	before := time.Now().Add(-time.Hour)
+	after := time.Now().Add(time.Hour)
+	ca, _, caKey, caPEM := cert_test.NewTestCaCert(cert.Version2, cert.Curve_CURVE25519, before, after, nil, nil, nil)
+	networks := []netip.Prefix{netip.MustParsePrefix("10.0.0.1/24")}
+	_, _, keyPEM, certPEM := cert_test.NewTestCert(cert.Version2, cert.Curve_CURVE25519, ca, caKey, "close-on-timer", before, after, networks, nil, nil)
+
+	caPath := filepath.Join(dir, "ca.pem")
+	certPath := filepath.Join(dir, "cert.pem")
+	keyPath := filepath.Join(dir, "key.pem")
+	require.NoError(t, os.WriteFile(caPath, caPEM, 0o600))
+	require.NoError(t, os.WriteFile(certPath, certPEM, 0o600))
+	require.NoError(t, os.WriteFile(keyPath, keyPEM, 0o600))
+
+	// tun disabled so no device/root is needed; routines: 2 so we exercise the
+	// multi-socket (SO_REUSEPORT) teardown, which is where dnclient runs.
+	configBody := fmt.Sprintf(`
+pki:
+  ca: %s
+  cert: %s
+  key: %s
+listen:
+  host: 127.0.0.1
+  port: 0
+tun:
+  disabled: true
+firewall:
+  outbound:
+    - port: any
+      proto: any
+      host: any
+  inbound:
+    - port: any
+      proto: any
+      host: any
+routines: 2
+`, caPath, certPath, keyPath)
+	require.NoError(t, os.WriteFile(filepath.Join(dir, "config.yml"), []byte(configBody), 0o600))
+
+	c := config.NewC(l)
+	require.NoError(t, c.Load(dir))
+
+	ctrl, err := nebula.Main(c, false, "close-on-timer", l, nil)
+	require.NoError(t, err)
+	require.NoError(t, ctrl.Start())
+
+	// Run like a live nebula, then close on a timer, exactly as dnclient does.
+	<-time.NewTimer(5 * time.Second).C
+
+	stopped := make(chan struct{})
+	go func() {
+		ctrl.Stop() // closes the udp sockets (shutdown(2)) and the tun
+		ctrl.Wait() // blocks until every reader goroutine has returned
+		close(stopped)
+	}()
+
+	select {
+	case <-stopped:
+		t.Log("nebula closed cleanly on timer")
+	case <-time.After(10 * time.Second):
+		buf := make([]byte, 1<<20)
+		n := runtime.Stack(buf, true)
+		t.Fatalf("nebula did NOT close within 10s of Stop(): a blocking reader never woke\n%s", buf[:n])
+	}
+}
@@ -44,6 +44,11 @@ type connectionManager struct {
 	inactivityTimeout       atomic.Int64
 	dropInactive            atomic.Bool

+	// Wake-from-sleep handling, sampled once per tick in Start
+	wakeDetector       *wakeDetector
+	clearOnWake        atomic.Bool
+	wakeClearThreshold atomic.Int64
+
 	l *slog.Logger
 }

@@ -54,6 +59,7 @@ func newConnectionManagerFromConfig(l *slog.Logger, c *config.C, hm *HostMap, p
 		punchy:        p,
 		relayUsed:     make(map[uint32]struct{}),
 		relayUsedLock: &sync.RWMutex{},
+		wakeDetector:  newWakeDetector(),
 	}

 	cm.reload(c, true)
@@ -98,12 +104,38 @@ func (cm *connectionManager) reload(c *config.C, initial bool) {
 			)
 		}
 	}
+
+	if initial || c.HasChanged("tunnels.clear_on_wake") {
+		old := cm.clearOnWake.Load()
+		cm.clearOnWake.Store(c.GetBool("tunnels.clear_on_wake", true))
+		if !initial {
+			cm.l.Info("Clear on wake setting has changed",
+				"oldBool", old,
+				"newBool", cm.clearOnWake.Load(),
+			)
+		}
+	}
+
+	if initial || c.HasChanged("tunnels.wake_clear_threshold") {
+		old := cm.getWakeClearThreshold()
+		cm.wakeClearThreshold.Store((int64)(c.GetDuration("tunnels.wake_clear_threshold", 30*time.Second)))
+		if !initial {
+			cm.l.Info("Wake clear threshold has changed",
+				"oldDuration", old,
+				"newDuration", cm.getWakeClearThreshold(),
+			)
+		}
+	}
 }

 func (cm *connectionManager) getInactivityTimeout() time.Duration {
 	return (time.Duration)(cm.inactivityTimeout.Load())
 }

+func (cm *connectionManager) getWakeClearThreshold() time.Duration {
+	return (time.Duration)(cm.wakeClearThreshold.Load())
+}
+
 func (cm *connectionManager) In(h *HostInfo) {
 	h.in.Store(true)
 }
@@ -136,6 +168,73 @@ func (cm *connectionManager) getAndResetTrafficCheck(h *HostInfo, now time.Time)
 	return in, out
 }

+// checkWake runs once per tick and clears every tunnel when the machine has just returned from system sleep.
+// Tunnels rarely survive a suspend: our NAT mappings have expired and our address has usually changed, so every
+// established hostinfo is a corpse that will eat 15-20s of traffic checks before the wheel declares it dead.
+// Clearing now means the first packet after wake starts a fresh handshake immediately.
+//
+// The suspend itself costs nothing here: the ticker driving us is frozen with the rest of the process and this
+// fires within one tick of resume.
+func (cm *connectionManager) checkWake() {
+	slept, ok := cm.wakeDetector.Sample()
+	if !ok || slept == 0 {
+		return
+	}
+
+	// The clock pair is read non-atomically, so scheduling jitter shows up as tiny sub-millisecond "sleeps".
+	// Keep the floor well above that so a zero/nonsense threshold can't clear tunnels on every tick.
+	threshold := max(cm.getWakeClearThreshold(), time.Second)
+
+	if slept < threshold {
+		// Short suspends (lid closed and quickly reopened) often come back before NAT state expires; those
+		// tunnels may well be alive, leave them to the normal traffic checks.
+		if slept >= time.Second {
+			cm.l.Debug("Woke from sleep below the clear threshold, leaving tunnels alone",
+				"sleptFor", slept,
+				"threshold", threshold,
+			)
+		}
+		return
+	}
+
+	if !cm.clearOnWake.Load() {
+		cm.l.Info("Woke from sleep, tunnels.clear_on_wake is disabled so tunnels are left to the normal traffic checks", "sleptFor", slept)
+		return
+	}
+
+	closed := cm.clearAllTunnels()
+	cm.l.Info("Woke from sleep, cleared tunnels", "sleptFor", slept, "tunnelsCleared", closed)
+
+	// Our public address almost certainly changed; get it to the lighthouses as soon as possible so peers can
+	// find us again. The update rides over a fresh lighthouse handshake. If the network isn't back up yet these
+	// sends fail harmlessly and the periodic update worker retries within lighthouse.interval.
+	cm.intf.lightHouse.TriggerUpdate()
+}
+
+// clearAllTunnels closes every tunnel in the hostmap locally, without notifying the remotes. It is the wake-from-
+// sleep counterpart to Control.CloseAllTunnels: after a suspend the remotes stopped hearing from us long ago, and
+// close packets fired into a network that may not even be up yet are wasted, so we only tear down our own state
+// and let the next packet to each host start a fresh handshake.
+func (cm *connectionManager) clearAllTunnels() int {
+	cm.hostMap.RLock()
+	hostinfos := make([]*HostInfo, 0, len(cm.hostMap.Indexes))
+	for _, h := range cm.hostMap.Indexes {
+		hostinfos = append(hostinfos, h)
+	}
+	cm.hostMap.RUnlock()
+
+	for _, h := range hostinfos {
+		cm.intf.closeTunnel(h)
+	}
+
+	// With every tunnel gone no relay can be in use, drop the usage tracking wholesale.
+	cm.relayUsedLock.Lock()
+	clear(cm.relayUsed)
+	cm.relayUsedLock.Unlock()
+
+	return len(hostinfos)
+}
+
 func (cm *connectionManager) Start(ctx context.Context) {
 	clockSource := time.NewTicker(cm.trafficTimer.t.tickDuration)
 	defer clockSource.Stop()
@@ -150,6 +249,7 @@ func (cm *connectionManager) Start(ctx context.Context) {
 			return

 		case now := <-clockSource.C:
+			cm.checkWake()
 			cm.trafficTimer.Advance(now)
 			for {
 				localIndex, has := cm.trafficTimer.Purge()
@@ -501,3 +501,85 @@ func (d *dummyCert) MarshalJSON() ([]byte, error) {
 func (d *dummyCert) Copy() cert.Certificate {
 	return d
 }
+
+func TestConnectionManager_WakeClear(t *testing.T) {
+	l := test.NewLogger()
+	localrange := netip.MustParsePrefix("10.1.1.1/24")
+	vpnIp := netip.MustParseAddr("172.1.1.2")
+	preferredRanges := []netip.Prefix{localrange}
+
+	// Very incomplete mock objects
+	hostMap := newHostMap(l)
+	hostMap.preferredRanges.Store(&preferredRanges)
+
+	cs := &CertState{
+		initiatingVersion: cert.Version1,
+		privateKey:        []byte{},
+		v1Cert:            &dummyCert{version: cert.Version1},
+		v1Credential:      nil,
+	}
+
+	lh := newTestLighthouse()
+	ifce := &Interface{
+		hostMap:          hostMap,
+		inside:           &overlaytest.NoopTun{},
+		outside:          &udp.NoopConn{},
+		firewall:         &Firewall{},
+		lightHouse:       lh,
+		pki:              &PKI{},
+		handshakeManager: NewHandshakeManager(l, hostMap, lh, &udp.NoopConn{}, defaultHandshakeConfig),
+		l:                l,
+	}
+	ifce.pki.cs.Store(cs)
+
+	// Create manager
+	conf := config.NewC(test.NewLogger())
+	punchy := NewPunchyFromConfig(test.NewLogger(), conf, nil)
+	nc := newConnectionManagerFromConfig(test.NewLogger(), conf, hostMap, punchy)
+	nc.intf = ifce
+
+	// Drive the wake detector from a fake clock pair
+	suspended := time.Duration(0)
+	nc.wakeDetector = &wakeDetector{read: func() (time.Duration, bool) { return suspended, true }}
+	nc.checkWake() // primes the baseline
+
+	addTunnel := func(localIndex uint32) *HostInfo {
+		hostinfo := &HostInfo{
+			vpnAddrs:      []netip.Addr{vpnIp},
+			localIndexId:  localIndex,
+			remoteIndexId: 9901,
+		}
+		hostinfo.ConnectionState = &ConnectionState{
+			myCert: &dummyCert{version: cert.Version1},
+		}
+		nc.hostMap.unlockedAddHostInfo(hostinfo, ifce)
+		return hostinfo
+	}
+
+	addTunnel(1099)
+	nc.RelayUsed(5000)
+
+	// No suspend, nothing happens
+	nc.checkWake()
+	assert.Contains(t, nc.hostMap.Indexes, uint32(1099))
+
+	// A suspend below the threshold leaves tunnels alone
+	suspended += 5 * time.Second
+	nc.checkWake()
+	assert.Contains(t, nc.hostMap.Indexes, uint32(1099))
+
+	// A suspend past the threshold clears everything, including relay usage tracking
+	suspended += time.Hour
+	nc.checkWake()
+	assert.Empty(t, nc.hostMap.Indexes)
+	assert.Empty(t, nc.hostMap.Hosts)
+	assert.Empty(t, nc.relayUsed)
+
+	// With clear_on_wake disabled the tunnels survive a long suspend
+	addTunnel(1100)
+	nc.clearOnWake.Store(false)
+	suspended += time.Hour
+	nc.checkWake()
+	assert.Contains(t, nc.hostMap.Indexes, uint32(1100))
+	assert.Contains(t, nc.hostMap.Hosts, vpnIp)
+}
@@ -2,11 +2,13 @@ package nebula

 import (
 	"encoding/json"
+	"log/slog"
 	"sync"
 	"sync/atomic"

 	"github.com/slackhq/nebula/cert"
 	"github.com/slackhq/nebula/handshake"
+	"github.com/slackhq/nebula/header"
 	"github.com/slackhq/nebula/noiseutil"
 )

@@ -20,6 +22,7 @@ type ConnectionState struct {
 	initiator      bool
 	messageCounter atomic.Uint64
 	window         *Bits
+	decryptLock    sync.Mutex
 	writeLock      sync.Mutex
 }

@@ -54,3 +57,52 @@ func (cs *ConnectionState) MarshalJSON() ([]byte, error) {
 func (cs *ConnectionState) Curve() cert.Curve {
 	return cs.myCert.Curve()
 }
+
+func (cs *ConnectionState) Decrypt(l *slog.Logger, messageCounter uint64, out []byte, packet []byte, nb []byte) ([]byte, error) {
+	var err error
+	cs.decryptLock.Lock()
+	result := cs.window.Check(l, messageCounter)
+	cs.decryptLock.Unlock()
+	if !result {
+		return nil, ErrAlreadySeen
+	}
+
+	out, err = cs.dKey.DecryptDanger(out, packet[:header.Len], packet[header.Len:], messageCounter, nb)
+	if err != nil {
+		return nil, err
+	}
+
+	cs.decryptLock.Lock()
+	result = cs.window.Update(l, messageCounter)
+	cs.decryptLock.Unlock()
+	if !result {
+		return nil, ErrAlreadySeen
+	}
+	return out, nil
+}
+
+// VerifyRelay verifies AEAD protected (but not encrypted) relay frames. packet must be length-checked by the caller.
+func (cs *ConnectionState) VerifyRelay(l *slog.Logger, messageCounter uint64, packet []byte, nb []byte) error {
+	cs.decryptLock.Lock()
+	result := cs.window.Check(l, messageCounter)
+	cs.decryptLock.Unlock()
+	if !result {
+		return ErrAlreadySeen
+	}
+
+	signedPayload := packet[:len(packet)-cs.dKey.Overhead()]
+	signatureValue := packet[len(packet)-cs.dKey.Overhead():]
+	_, err := cs.dKey.DecryptDanger(nil, signedPayload, signatureValue, messageCounter, nb)
+	if err != nil {
+		return err
+	}
+
+	cs.decryptLock.Lock()
+	result = cs.window.Update(l, messageCounter)
+	cs.decryptLock.Unlock()
+	if !result {
+		return ErrAlreadySeen
+	}
+
+	return nil
+}
@@ -97,8 +97,7 @@ func (d *dnsServer) reload(c *config.C, initial bool) error {
 	newAddr := getDnsServerAddr(c)

 	d.serverMu.Lock()
-	running := d.server
-	runningStarted := d.started
+	running := d.server != nil
 	sameAddr := d.addr == newAddr
 	d.addr = newAddr
 	d.enabled.Store(enabled)
@@ -112,7 +111,7 @@ func (d *dnsServer) reload(c *config.C, initial bool) error {
 	}

 	if !enabled {
-		if running != nil {
+		if running {
 			d.Stop()
 		}
 		// Drop any records that accumulated while enabled; a later re-enable
@@ -121,12 +120,12 @@ func (d *dnsServer) reload(c *config.C, initial bool) error {
 		return nil
 	}

-	if running == nil {
+	if !running {
 		// Was disabled (or never started); bring it up now.
 		go d.Start()
 	} else if !sameAddr {
-		d.shutdownServer(running, runningStarted, "reload")
-		// Old Start goroutine has now exited; bring up a fresh listener on the new address.
+		// Stop clears the slot before shutting down, otherwise the Start below can find the dying server and refuse
+		d.Stop()
 		go d.Start()
 	}

@@ -162,7 +161,9 @@ func (d *dnsServer) Start() {

 	started := make(chan struct{})
 	d.serverMu.Lock()
-	if d.ctx.Err() != nil {
+	// Re-check enabled under the lock, a disable that raced our check above snapshots the slot under it too.
+	// Two reloads in quick succession can both spawn a Start, the loser would orphan the live listener past Stop
+	if d.ctx.Err() != nil || d.server != nil || !d.enabled.Load() {
 		d.serverMu.Unlock()
 		return
 	}
@@ -200,6 +201,14 @@ func (d *dnsServer) Start() {
 		close(started)
 	}

+	// Release our slot, unless a reload already replaced us, so a dead listener can't block a future Start
+	d.serverMu.Lock()
+	if d.server == server {
+		d.server = nil
+		d.started = nil
+	}
+	d.serverMu.Unlock()
+
 	if err != nil {
 		d.l.Warn("Failed to run the DNS responder", "error", err)
 	}
@@ -194,14 +194,51 @@ func TestDnsServer_reload_initial_serveDnsWithoutLighthouse(t *testing.T) {
 }

 func TestDnsServer_reload_sameAddr_noOp(t *testing.T) {
+	port := freeUDPPort(t)
 	ds, c := newTestDnsServer(t)
-	setDnsConfig(c, "127.0.0.1", "0", true, true)
-
+	setDnsConfig(c, "127.0.0.1", port, true, true)
 	require.NoError(t, ds.reload(c, true))
-	// No server running yet, no addr change. Reload should not spawn anything.
+
+	go ds.Start()
+	waitForBind(t, ds)
+
+	ds.serverMu.Lock()
+	before := ds.server
+	ds.serverMu.Unlock()
+	require.NotNil(t, before)
+
+	// Same address, so the running listener must be left alone rather than rebuilt under live queries
 	require.NoError(t, ds.reload(c, false))
 	assert.True(t, ds.enabled.Load())
-	assert.Nil(t, ds.server)
+
+	ds.serverMu.Lock()
+	after := ds.server
+	ds.serverMu.Unlock()
+	assert.Same(t, before, after, "a same-address reload must not restart the listener")
+
+	ds.Stop()
+}
+
+// The branch the old sameAddr test was accidentally hitting: enabled with nothing running means reload starts it.
+func TestDnsServer_reload_whenNotRunning_starts(t *testing.T) {
+	port := freeUDPPort(t)
+	ds, c := newTestDnsServer(t)
+	setDnsConfig(c, "127.0.0.1", port, true, true)
+
+	// initial only records config, it never starts anything
+	require.NoError(t, ds.reload(c, true))
+	ds.serverMu.Lock()
+	assert.Nil(t, ds.server, "the initial reload must not start a listener")
+	ds.serverMu.Unlock()
+
+	require.NoError(t, ds.reload(c, false))
+	waitForBind(t, ds)
+
+	ds.serverMu.Lock()
+	assert.NotNil(t, ds.server, "a reload with nothing running should bring DNS up")
+	ds.serverMu.Unlock()
+
+	ds.Stop()
 }

 func TestDnsServer_StartStop_lifecycle(t *testing.T) {
@@ -427,3 +464,168 @@ func waitFor(t *testing.T, cond func() bool) {
 	}
 	t.Fatal("timed out waiting for condition")
 }
+
+// Two reloads in quick succession, or a HUP before Control.Start, can race two Starts at the same listener.
+func TestDnsServer_Start_isIdempotent(t *testing.T) {
+	port := freeUDPPort(t)
+	ds, c := newTestDnsServer(t)
+	setDnsConfig(c, "127.0.0.1", port, true, true)
+	require.NoError(t, ds.reload(c, true))
+
+	go ds.Start()
+	waitForBind(t, ds)
+
+	ds.serverMu.Lock()
+	first := ds.server
+	ds.serverMu.Unlock()
+	require.NotNil(t, first)
+
+	// If the second Start replaces the tracked server, Stop kills the wrong one and the port leaks
+	done := make(chan struct{})
+	go func() {
+		ds.Start()
+		close(done)
+	}()
+	select {
+	case <-done:
+	case <-time.After(time.Second * 5):
+		t.Fatal("second Start never returned")
+	}
+
+	ds.serverMu.Lock()
+	second := ds.server
+	ds.serverMu.Unlock()
+	assert.Same(t, first, second, "a second Start must not replace the running server")
+
+	// The real proof, after Stop the port must actually be free
+	ds.Stop()
+	waitFor(t, func() bool {
+		pc, err := net.ListenPacket("udp", "127.0.0.1:"+port)
+		if err != nil {
+			return false
+		}
+		_ = pc.Close()
+		return true
+	})
+}
+
+// An address change must actually end up listening on the new port. Start's guard refuses when a server is already
+// installed, so reload has to clear the slot before shutting the old one down.
+func TestDnsServer_reload_addrChange_restarts(t *testing.T) {
+	first := freeUDPPort(t)
+	second := freeUDPPort(t)
+
+	ds, c := newTestDnsServer(t)
+	setDnsConfig(c, "127.0.0.1", first, true, true)
+	require.NoError(t, ds.reload(c, true))
+
+	go ds.Start()
+	waitForBind(t, ds)
+
+	// Cycle a few times, the failure this guards against depends on which goroutine wins serverMu
+	for i := range 8 {
+		want := second
+		if i%2 == 1 {
+			want = first
+		}
+		setDnsConfig(c, "127.0.0.1", want, true, true)
+		require.NoError(t, ds.reload(c, false))
+		waitForBind(t, ds)
+
+		ds.serverMu.Lock()
+		srv := ds.server
+		ds.serverMu.Unlock()
+		require.NotNil(t, srv, "reload left DNS down instead of restarting it")
+		require.Equal(t, "127.0.0.1:"+want, srv.Addr, "reload should be serving the new address")
+	}
+
+	// Land back on second so the port assertions below are meaningful
+	setDnsConfig(c, "127.0.0.1", second, true, true)
+	require.NoError(t, ds.reload(c, false))
+	waitForBind(t, ds)
+
+	// The old port must be released and the new one actually held
+	waitFor(t, func() bool {
+		pc, err := net.ListenPacket("udp", "127.0.0.1:"+first)
+		if err != nil {
+			return false
+		}
+		_ = pc.Close()
+		return true
+	})
+	_, err := net.ListenPacket("udp", "127.0.0.1:"+second)
+	require.Error(t, err, "the new address should be bound by the DNS responder")
+
+	ds.Stop()
+}
+
+// A listener that dies on its own must release the slot, or a later same-addr reload sees it as running and no-ops.
+func TestDnsServer_Start_bindFailure_releasesSlot(t *testing.T) {
+	port := freeUDPPort(t)
+	blocker, err := net.ListenPacket("udp", "127.0.0.1:"+port)
+	require.NoError(t, err)
+
+	ds, c := newTestDnsServer(t)
+	setDnsConfig(c, "127.0.0.1", port, true, true)
+	require.NoError(t, ds.reload(c, true))
+
+	ds.Start() // returns once the bind fails
+
+	ds.serverMu.Lock()
+	assert.Nil(t, ds.server, "a listener that failed to bind must not stay parked in the slot")
+	ds.serverMu.Unlock()
+
+	// With the slot released, a reload can retry once the port frees up
+	require.NoError(t, blocker.Close())
+	require.NoError(t, ds.reload(c, false))
+	waitForBind(t, ds)
+
+	ds.serverMu.Lock()
+	assert.NotNil(t, ds.server, "a same-addr reload should retry after a failed bind")
+	ds.serverMu.Unlock()
+
+	ds.Stop()
+}
+
+// A disable that lands while Start is between its unlocked check and the guard must not leave a listener behind.
+func TestDnsServer_Start_refusesWhenDisabledUnderLock(t *testing.T) {
+	port := freeUDPPort(t)
+	ds, c := newTestDnsServer(t)
+	setDnsConfig(c, "127.0.0.1", port, true, true)
+	require.NoError(t, ds.reload(c, true))
+	require.True(t, ds.enabled.Load())
+
+	// Holding serverMu parks Start on the lock, the only way to land the disable in that window on purpose
+	ds.serverMu.Lock()
+
+	done := make(chan struct{})
+	go func() {
+		ds.Start()
+		close(done)
+	}()
+
+	select {
+	case <-done:
+		ds.serverMu.Unlock()
+		t.Fatal("Start returned early, the test never exercised the window")
+	case <-time.After(time.Millisecond * 100):
+	}
+
+	// The disable reload's critical section. It sees nothing running, so it never calls Stop.
+	ds.enabled.Store(false)
+	ds.serverMu.Unlock()
+
+	select {
+	case <-done:
+	case <-time.After(time.Second * 5):
+		t.Fatal("Start never returned")
+	}
+
+	ds.serverMu.Lock()
+	assert.Nil(t, ds.server, "Start must not install a listener a disable already cancelled")
+	ds.serverMu.Unlock()
+
+	pc, err := net.ListenPacket("udp", "127.0.0.1:"+port)
+	require.NoError(t, err, "an orphaned listener is still holding the port")
+	_ = pc.Close()
+}
@@ -725,6 +725,70 @@ func TestReestablishRelays(t *testing.T) {

 }

+func TestRelayHandshakeOverDisestablishedEntry(t *testing.T) {
+	t.Parallel()
+	// If them tears down the tunnel while me keeps Established relay state, me's next
+	// handshake flows through the relay with no fresh CreateRelayRequest and lands on
+	// them's Disestablished terminal relay entry. them must re-establish that entry, or
+	// its first transmit deletes its only relay and the tunnel is born transmit-dead:
+	// them can receive but every send is silently dropped.
+	ca, _, caKey, _ := cert_test.NewTestCaCert(cert.Version1, cert.Curve_CURVE25519, time.Now(), time.Now().Add(10*time.Minute), nil, nil, []string{})
+	myControl, myVpnIpNet, _, _ := newSimpleServer(cert.Version1, ca, caKey, "me     ", "10.128.0.1/24", m{"relay": m{"use_relays": true}})
+	relayControl, relayVpnIpNet, relayUdpAddr, _ := newSimpleServer(cert.Version1, ca, caKey, "relay  ", "10.128.0.128/24", m{"relay": m{"am_relay": true}})
+	theirControl, theirVpnIpNet, theirUdpAddr, _ := newSimpleServer(cert.Version1, ca, caKey, "them   ", "10.128.0.2/24", m{"relay": m{"use_relays": true}})
+
+	// Teach my how to get to the relay and that their can be reached via the relay
+	myControl.InjectLightHouseAddr(relayVpnIpNet[0].Addr(), relayUdpAddr)
+	myControl.InjectRelays(theirVpnIpNet[0].Addr(), []netip.Addr{relayVpnIpNet[0].Addr()})
+	relayControl.InjectLightHouseAddr(theirVpnIpNet[0].Addr(), theirUdpAddr)
+
+	// Build a router so we don't have to reason who gets which packet
+	r := router.NewR(t, myControl, relayControl, theirControl)
+	defer r.RenderFlow()
+
+	// Start the servers
+	myControl.Start()
+	relayControl.Start()
+	theirControl.Start()
+
+	t.Log("Trigger a handshake from me to them via the relay")
+	myControl.InjectTunPacket(BuildTunUDPPacket(theirVpnIpNet[0].Addr(), 80, myVpnIpNet[0].Addr(), 80, []byte("Hi from me")))
+
+	p := r.RouteForAllUntilTxTun(theirControl)
+	assertUdpPacket(t, []byte("Hi from me"), p, myVpnIpNet[0].Addr(), theirVpnIpNet[0].Addr(), 80, 80)
+	oldIdx := myControl.GetHostInfoByVpnAddr(theirVpnIpNet[0].Addr(), false).LocalIndex
+
+	t.Log("Close the tunnel on them only, marking their relay entry Disestablished")
+	theirControl.CloseTunnel(myVpnIpNet[0].Addr(), true)
+
+	t.Log("Re-handshake from me, riding the still-Established relay state")
+	myControl.ReHandshake(theirVpnIpNet[0].Addr())
+	for {
+		h := myControl.GetHostInfoByVpnAddr(theirVpnIpNet[0].Addr(), false)
+		if h != nil && h.LocalIndex != oldIdx && h.RemoteIndex != 0 {
+			break
+		}
+		r.RouteForAllExitFunc(func(*udp.Packet, *nebula.Control) router.ExitType {
+			return router.RouteAndExit
+		})
+	}
+
+	hAtThem := theirControl.GetHostInfoByVpnAddr(myVpnIpNet[0].Addr(), false)
+	require.NotNil(t, hAtThem, "them should have completed the relayed handshake")
+	require.Equal(t, []netip.Addr{relayVpnIpNet[0].Addr()}, hAtThem.CurrentRelaysToMe, "them should know a relay for the new tunnel")
+
+	t.Log("Send from them to me; their only relay entry must survive the transmit")
+	theirControl.InjectTunPacket(BuildTunUDPPacket(myVpnIpNet[0].Addr(), 80, theirVpnIpNet[0].Addr(), 80, []byte("Hi from them")))
+	require.Never(t, func() bool {
+		h := theirControl.GetHostInfoByVpnAddr(myVpnIpNet[0].Addr(), false)
+		return h == nil || len(h.CurrentRelaysToMe) == 0
+	}, time.Second, 10*time.Millisecond, "them deleted its only relay entry; the tunnel is permanently transmit-dead")
+
+	p = r.RouteForAllUntilTxTun(myControl)
+	assertUdpPacket(t, []byte("Hi from them"), p, theirVpnIpNet[0].Addr(), myVpnIpNet[0].Addr(), 80, 80)
+	r.RenderHostmaps("Final hostmaps", myControl, relayControl, theirControl)
+}
+
 func TestStage1RaceRelays(t *testing.T) {
 	t.Parallel()
 	//NOTE: this is a race between me and relay resulting in a full tunnel from me to them via relay
@@ -390,6 +390,20 @@ logging:
  # This setting is reloadable
  #inactivity_timeout: 10m

+  # clear_on_wake controls whether all tunnels are immediately torn down (locally, without notifying the remotes)
+  # when the machine detects it has just woken from system sleep. Tunnels rarely survive a suspend: NAT mappings
+  # expire and the machine's address usually changes, so waiting for the normal liveness checks costs 15-20 seconds
+  # of black-holed traffic per tunnel after wake. Clearing them means the first packet after wake starts a fresh
+  # handshake right away.
+  # This setting is reloadable
+  #clear_on_wake: true
+
+  # wake_clear_threshold is the minimum time the machine must have been suspended for clear_on_wake to act.
+  # Suspends shorter than this often come back before NAT state expires, so those tunnels may still be alive and
+  # are left to the normal liveness checks. Values below 1s are treated as 1s.
+  # This setting is reloadable
+  #wake_clear_threshold: 30s
+
 # Nebula security group configuration
 firewall:
  # Action to take when a packet is not allowed by the firewall rules.
@@ -8,6 +8,15 @@ Before=sshd.service
 Type=notify
 NotifyAccess=main
 SyslogIdentifier=nebula
+
+# Uncomment to run as an unprivileged user with only CAP_NET_ADMIN. Requires a
+# nebula user that owns the config directory. Add CAP_NET_BIND_SERVICE to both
+# lines if any listener (lighthouse DNS, listen.port, stats, sshd) binds <1024.
+#User=nebula
+#Group=nebula
+#CapabilityBoundingSet=CAP_NET_ADMIN
+#AmbientCapabilities=CAP_NET_ADMIN
+
 ExecReload=/bin/kill -HUP $MAINPID
 ExecStart=/usr/local/bin/nebula -config /etc/nebula/config.yml
 Restart=always
@@ -44,8 +44,8 @@ type Firewall struct {
 	InRules  *FirewallTable
 	OutRules *FirewallTable

-	InSendReject  bool
-	OutSendReject bool
+	InboundSendReject  bool
+	OutboundSendReject bool

 	//TODO: we should have many more options for TCP, an option for ICMP, and mimic the kernel a bit better
 	// https://www.kernel.org/doc/Documentation/networking/nf_conntrack-sysctl.txt
@@ -216,23 +216,23 @@ func NewFirewallFromConfig(l *slog.Logger, cs *CertState, c *config.C) (*Firewal
 	inboundAction := c.GetString("firewall.inbound_action", "drop")
 	switch inboundAction {
 	case "reject":
-		fw.InSendReject = true
+		fw.InboundSendReject = true
 	case "drop":
-		fw.InSendReject = false
+		fw.InboundSendReject = false
 	default:
 		l.Warn("invalid firewall.inbound_action, defaulting to `drop`", "action", inboundAction)
-		fw.InSendReject = false
+		fw.InboundSendReject = false
 	}

 	outboundAction := c.GetString("firewall.outbound_action", "drop")
 	switch outboundAction {
 	case "reject":
-		fw.OutSendReject = true
+		fw.OutboundSendReject = true
 	case "drop":
-		fw.OutSendReject = false
+		fw.OutboundSendReject = false
 	default:
 		l.Warn("invalid firewall.outbound_action, defaulting to `drop`", "action", outboundAction)
-		fw.OutSendReject = false
+		fw.OutboundSendReject = false
 	}

 	err := AddFirewallRulesFromConfig(l, false, c, fw)
@@ -24,12 +24,12 @@ require (
 	github.com/vishvananda/netlink v1.3.1
 	go.uber.org/goleak v1.3.0
 	go.yaml.in/yaml/v3 v3.0.4
-	golang.org/x/crypto v0.53.0
+	golang.org/x/crypto v0.54.0
 	golang.org/x/exp v0.0.0-20230725093048-515e97ebf090
-	golang.org/x/net v0.56.0
-	golang.org/x/sync v0.21.0
-	golang.org/x/sys v0.46.0
-	golang.org/x/term v0.44.0
+	golang.org/x/net v0.57.0
+	golang.org/x/sync v0.22.0
+	golang.org/x/sys v0.47.0
+	golang.org/x/term v0.45.0
 	golang.zx2c4.com/wintun v0.0.0-20230126152724-0fa3db229ce2
 	golang.zx2c4.com/wireguard v0.0.0-20230325221338-052af4a8072b
 	golang.zx2c4.com/wireguard/windows v1.0.1
@@ -162,8 +162,8 @@ golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACk
 golang.org/x/crypto v0.0.0-20191011191535-87dc89f01550/go.mod h1:yigFU9vqHzYiE8UmvKecakEJjdnWj3jj499lnFckfCI=
 golang.org/x/crypto v0.0.0-20200622213623-75b288015ac9/go.mod h1:LzIPMQfyMNhhGPhUkYOs5KpL4U8rLKemX1yGLhDgUto=
 golang.org/x/crypto v0.0.0-20210322153248-0c34fe9e7dc2/go.mod h1:T9bdIzuCu7OtxOm1hfPfRQxPLYneinmdGuTeoZ9dtd4=
-golang.org/x/crypto v0.53.0 h1:QZ4Muo8THX6CizN2vPPd5fBGHyogrdK9fG4wLPFUsto=
-golang.org/x/crypto v0.53.0/go.mod h1:DNLU434OwVakk9PzuwV8w62mAJpRJL3vsgcfp4Qnsio=
+golang.org/x/crypto v0.54.0 h1:YLIA59K4fiNzHzjnZt2tUJQjQtUWfWbeHBqKtk3eScw=
+golang.org/x/crypto v0.54.0/go.mod h1:KWL8ny2AZdGR2cWmzeHrp2azQPGogOv+HeQaVEXC2dk=
 golang.org/x/exp v0.0.0-20230725093048-515e97ebf090 h1:Di6/M8l0O2lCLc6VVRWhgCiApHV8MnQurBnFSHsQtNY=
 golang.org/x/exp v0.0.0-20230725093048-515e97ebf090/go.mod h1:FXUEEKJgO7OQYeo8N01OfiKP8RXMtf6e8aTskBGqWdc=
 golang.org/x/lint v0.0.0-20200302205851-738671d3881b/go.mod h1:3xt1FjdF8hUf6vQPIChWIBhFzV8gjjsPE/fR3IyQdNY=
@@ -182,8 +182,8 @@ golang.org/x/net v0.0.0-20200226121028-0de0cce0169b/go.mod h1:z5CRVTTTmAJ677TzLL
 golang.org/x/net v0.0.0-20200625001655-4c5254603344/go.mod h1:/O7V0waA8r7cgGh81Ro3o1hOxt32SMVPicZroKQ2sZA=
 golang.org/x/net v0.0.0-20201021035429-f5854403a974/go.mod h1:sp8m0HH+o8qH0wwXwYZr8TS3Oi6o0r6Gce1SSxlDquU=
 golang.org/x/net v0.0.0-20210226172049-e18ecbb05110/go.mod h1:m0MpNAwzfU5UDzcl9v0D8zg8gWTRqZa9RBIspLL5mdg=
-golang.org/x/net v0.56.0 h1:Rw8j/hFzGvJUZwNBXnAtf5sVDVt+65SK2C7IxCxZt5o=
-golang.org/x/net v0.56.0/go.mod h1:D3Ku6r+V6JROoZK144D2XfMHFcMq/0zSfLelVTCFKec=
+golang.org/x/net v0.57.0 h1:K5+3DljvIuDG9/Jv9rvyMywYNFCQ9RSUY6OOTTkT+tE=
+golang.org/x/net v0.57.0/go.mod h1:KpXc8iv+r3XplLAG/f7Jsf9RPszJzdR0f58q9vGOuEU=
 golang.org/x/oauth2 v0.0.0-20190226205417-e64efc72b421/go.mod h1:gOpvHmFTYa4IltrdGE7lF6nIHvwfUNPOp7c8zoXwtLw=
 golang.org/x/sync v0.0.0-20181108010431-42b317875d0f/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sync v0.0.0-20181221193216-37e7f081c4d4/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
@@ -191,8 +191,8 @@ golang.org/x/sync v0.0.0-20190423024810-112230192c58/go.mod h1:RxMgew5VJxzue5/jJ
 golang.org/x/sync v0.0.0-20190911185100-cd5d95a43a6e/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sync v0.0.0-20201020160332-67f06af15bc9/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sync v0.0.0-20201207232520-09787c993a3a/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
-golang.org/x/sync v0.21.0 h1:HLII4xRRTtCRkxYp4HNFF0Js/Og6q2i++KXbg0gHCwM=
-golang.org/x/sync v0.21.0/go.mod h1:9xrNwdLfx4jkKbNva9FpL6vEN7evnE43NNNJQ2LF3+0=
+golang.org/x/sync v0.22.0 h1:SZjpbeLmrCk4xhRSZFNZW5gFUeCeFgjekvI/+gfScek=
+golang.org/x/sync v0.22.0/go.mod h1:9xrNwdLfx4jkKbNva9FpL6vEN7evnE43NNNJQ2LF3+0=
 golang.org/x/sys v0.0.0-20180905080454-ebe1bf3edb33/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
 golang.org/x/sys v0.0.0-20181116152217-5ac8a444bdc5/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
 golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
@@ -208,11 +208,11 @@ golang.org/x/sys v0.0.0-20210124154548-22da62e12c0c/go.mod h1:h1NjWce9XRLGQEsW7w
 golang.org/x/sys v0.0.0-20210603081109-ebe580a85c40/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.2.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
 golang.org/x/sys v0.10.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
-golang.org/x/sys v0.46.0 h1:noSf2Fq6F8DBgS+LysIkx7rIExoNHJsxOAtPp4rthXw=
-golang.org/x/sys v0.46.0/go.mod h1:4GL1E5IUh+htKOUEOaiffhrAeqysfVGipDYzABqnCmw=
+golang.org/x/sys v0.47.0 h1:o7XGOvZQCADBQQ4Y7VNq2dRWQR7JmOUW8Kxx4ZsNgWs=
+golang.org/x/sys v0.47.0/go.mod h1:4GL1E5IUh+htKOUEOaiffhrAeqysfVGipDYzABqnCmw=
 golang.org/x/term v0.0.0-20201126162022-7de9c90e9dd1/go.mod h1:bj7SfCRtBDWHUb9snDiAeCFNEtKQo2Wmx5Cou7ajbmo=
-golang.org/x/term v0.44.0 h1:0rLvDRCtNj0gZkyIXhCyOb2OAzEhLVqc4B+hrsBhrmc=
-golang.org/x/term v0.44.0/go.mod h1:7ze4MdzUzLXpSAoFP1H0bOI9aXDqveSvatT5vKcFh2Y=
+golang.org/x/term v0.45.0 h1:NwWyBmoJCbfTHpxrWoZ9C6/VxOf7ic219I8xZZFdrf0=
+golang.org/x/term v0.45.0/go.mod h1:9aqxs0blBcrm/n0L9QW0aRVD+ktan8ssZromtqJC43w=
 golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
 golang.org/x/text v0.3.2/go.mod h1:bEr9sfX3Q8Zfm5fL9x+3itogRgK3+ptLWKqgva+5dAk=
 golang.org/x/text v0.3.3/go.mod h1:5Zoc/QRtKVWzQhOtBMvqHzDpF6irO9z98xDceosuGiQ=
@@ -529,7 +529,9 @@ func (hm *HandshakeManager) DeleteHostInfo(hostinfo *HostInfo) {

 func (hm *HandshakeManager) unlockedDeleteHostInfo(hostinfo *HostInfo) {
 	for _, addr := range hostinfo.vpnAddrs {
-		delete(hm.vpnIps, addr)
+		if cur, ok := hm.vpnIps[addr]; ok && cur.hostinfo == hostinfo {
+			delete(hm.vpnIps, addr)
+		}
 	}

 	if len(hm.vpnIps) == 0 {
@@ -1077,7 +1079,7 @@ func (hm *HandshakeManager) sendHandshakeResponse(via ViaSender, msg []byte, hos
 		hostinfo.relayState.InsertRelayTo(via.relayHI.vpnAddrs[0])
 		// We received a valid handshake on this relay, so make sure the relay
 		// state reflects that, in case it had been marked Disestablished.
-		via.relayHI.relayState.UpdateRelayForByIdxState(via.remoteIdx, Established)
+		via.relayHI.relayState.UpdateRelayForByIdxState(via.relay.LocalIndex, Established)
 		f.SendVia(via.relayHI, via.relay, msg, make([]byte, 12), make([]byte, mtu), false)
 		f.l.Info("Handshake message sent", append(logFields, "relay", via.relayHI.vpnAddrs[0])...)
 	}
@@ -287,7 +287,6 @@ type HostInfo struct {
 type ViaSender struct {
 	UdpAddr   netip.AddrPort
 	relayHI   *HostInfo // relayHI is the host info object of the relay
-	remoteIdx uint32    // remoteIdx is the index included in the header of the received packet
 	relay     *Relay    // relay contains the rest of the relay information, including the PeerIP of the host trying to communicate with us.
 	IsRelayed bool      // IsRelayed is true if the packet was sent through a relay
 }
@@ -87,7 +87,7 @@ func (f *Interface) consumeInsidePacket(packet []byte, fwPacket *firewall.Packet
 }

 func (f *Interface) rejectInside(packet []byte, out []byte, q int) {
-	if !f.firewall.InSendReject {
+	if !f.firewall.OutboundSendReject {
 		return
 	}

@@ -103,7 +103,7 @@ func (f *Interface) rejectInside(packet []byte, out []byte, q int) {
 }

 func (f *Interface) rejectOutside(packet []byte, ci *ConnectionState, hostinfo *HostInfo, nb, out []byte, q int) {
-	if !f.firewall.OutSendReject {
+	if !f.firewall.InboundSendReject {
 		return
 	}

@@ -102,27 +102,31 @@ func (f *Interface) readOutsidePackets(via ViaSender, out []byte, packet []byte,
 		return
 	}

+	if len(packet) < header.Len+hostinfo.ConnectionState.dKey.Overhead() {
+		f.messageMetrics.RxInvalid(1)
+		if f.l.Enabled(context.Background(), slog.LevelDebug) {
+			f.l.Debug("packet too small", "from", via, "length", len(packet))
+		}
+		return
+	}
+
 	// All remaining packets are encrypted
-	ci := hostinfo.ConnectionState
-	if !ci.window.Check(f.l, h.MessageCounter) {
-		return
-	}
-
-	// Relay packets are special
 	if isMessageRelay {
+		// Relay packets are special, this branch should always early-return
+		if err = hostinfo.ConnectionState.VerifyRelay(f.l, h.MessageCounter, packet, nb); err != nil {
+			if f.l.Enabled(context.Background(), slog.LevelDebug) {
+				hostinfo.logger(f.l).Debug("Failed to verify relay packet", "error", err, "from", via, "header", h)
+			}
+			return
+		}
 		f.handleOutsideRelayPacket(hostinfo, via, out, packet, h, fwPacket, lhf, nb, q, localCache)
-
 		return
 	}

-	out, err = f.decrypt(hostinfo, h.MessageCounter, out, packet, h, nb)
+	out, err = hostinfo.ConnectionState.Decrypt(f.l, h.MessageCounter, out, packet, nb)
 	if err != nil {
 		if f.l.Enabled(context.Background(), slog.LevelDebug) {
-			hostinfo.logger(f.l).Debug("Failed to decrypt packet",
-				"error", err,
-				"from", via,
-				"header", h,
-			)
+			hostinfo.logger(f.l).Debug("Failed to decrypt packet", "error", err, "from", via, "header", h)
 		}
 		return
 	}
@@ -151,7 +155,7 @@ func (f *Interface) readOutsidePackets(via ViaSender, out []byte, packet []byte,
 			// No-op, useful for the Roaming and connectionManager side-effects above
 		case header.TestRequest:
 			//recycle the input packet ciphertext as our output buffer
-			f.send(header.Test, header.TestReply, ci, hostinfo, out, nb, packet)
+			f.send(header.Test, header.TestReply, hostinfo.ConnectionState, hostinfo, out, nb, packet)
 		default:
 			hostinfo.logger(f.l).Error("IsValidSubType was true, but unexpected test subtype seen", "from", via, "header", h)
 			return
@@ -170,27 +174,8 @@ func (f *Interface) readOutsidePackets(via ViaSender, out []byte, packet []byte,
 }

 func (f *Interface) handleOutsideRelayPacket(hostinfo *HostInfo, via ViaSender, out []byte, packet []byte, h *header.H, fwPacket *firewall.Packet, lhf *LightHouseHandler, nb []byte, q int, localCache firewall.ConntrackCache) {
-	// The entire body is sent as AD, not encrypted.
-	// The packet consists of a 16-byte parsed Nebula header, Associated Data-protected payload, and a trailing 16-byte AEAD signature value.
-	// The packet is guaranteed to be at least 16 bytes at this point, b/c it got past the h.Parse() call above. If it's
-	// otherwise malformed (meaning, there is no trailing 16 byte AEAD value), then this will result in at worst a 0-length slice
-	// which will gracefully fail in the DecryptDanger call.
-	signedPayload := packet[:len(packet)-hostinfo.ConnectionState.dKey.Overhead()]
-	signatureValue := packet[len(packet)-hostinfo.ConnectionState.dKey.Overhead():]
-	var err error
-	out, err = hostinfo.ConnectionState.dKey.DecryptDanger(out, signedPayload, signatureValue, h.MessageCounter, nb)
-	if err != nil {
-		return
-	}
-	// Advance the replay window now that the frame is authenticated
-	if !hostinfo.ConnectionState.window.Update(f.l, h.MessageCounter) {
-		if f.l.Enabled(context.Background(), slog.LevelDebug) {
-			hostinfo.logger(f.l).Debug("dropping out of window relay packet", "header", h)
-		}
-		return
-	}
-	// Successfully validated the thing. Get rid of the Relay header.
-	signedPayload = signedPayload[header.Len:]
+	// Successfully validated the thing. Get rid of the Relay header and the AEAD tag
+	signedPayload := packet[header.Len : len(packet)-hostinfo.ConnectionState.dKey.Overhead()]
 	// Pull the Roaming parts up here, and return in all call paths.
 	f.handleHostRoaming(hostinfo, via)
 	// Track usage of both the HostInfo and the Relay for the received & authenticated packet
@@ -214,7 +199,6 @@ func (f *Interface) handleOutsideRelayPacket(hostinfo *HostInfo, via ViaSender,
 		via = ViaSender{
 			UdpAddr:   via.UdpAddr,
 			relayHI:   hostinfo,
-			remoteIdx: relay.RemoteIndex,
 			relay:     relay,
 			IsRelayed: true,
 		}
@@ -235,9 +219,10 @@ func (f *Interface) handleOutsideRelayPacket(hostinfo *HostInfo, via ViaSender,
 		if targetRelay.State == Established {
 			switch targetRelay.Type {
 			case ForwardingType:
-				// Forward this packet through the relay tunnel
-				// Find the target HostInfo
-				f.SendVia(targetHI, targetRelay, signedPayload, nb, out, false)
+				// Forward this packet through the relay tunnel, rebuilding it in place.
+				// Encode overwrites the old outer header, and the new AEAD tag lands where the old one was
+				fwdBuf := packet[:0:len(packet)] // Cap to len(packet) to protect memory from a larger parent buffer
+				f.SendVia(targetHI, targetRelay, signedPayload, nb, fwdBuf, true)
 			case TerminalType:
 				hostinfo.logger(f.l).Error("Unexpected Relay Type of Terminal")
 				return
@@ -504,20 +489,6 @@ func parseV4(data []byte, incoming bool, fp *firewall.Packet) error {
 	return nil
 }

-func (f *Interface) decrypt(hostinfo *HostInfo, mc uint64, out []byte, packet []byte, h *header.H, nb []byte) ([]byte, error) {
-	var err error
-	out, err = hostinfo.ConnectionState.dKey.DecryptDanger(out, packet[:header.Len], packet[header.Len:], mc, nb)
-	if err != nil {
-		return nil, err
-	}
-
-	if !hostinfo.ConnectionState.window.Update(f.l, mc) {
-		return nil, ErrOutOfWindow
-	}
-
-	return out, nil
-}
-
 func (f *Interface) handleOutsideMessagePacket(hostinfo *HostInfo, out []byte, packet []byte, fwPacket *firewall.Packet, nb []byte, q int, localCache firewall.ConntrackCache) {
 	err := newPacket(out, true, fwPacket)
 	if err != nil {
@@ -4,12 +4,13 @@
 package udp

 import (
-	"context"
 	"encoding/binary"
+	"errors"
 	"fmt"
 	"log/slog"
 	"net"
 	"net/netip"
+	"sync/atomic"
 	"syscall"
 	"unsafe"

@@ -19,58 +20,51 @@ import (
 )

 type StdConn struct {
-	udpConn *net.UDPConn
-	rawConn syscall.RawConn
-	isV4    bool
-	l       *slog.Logger
-	batch   int
-}
-
-func setReusePort(network, address string, c syscall.RawConn) error {
-	var opErr error
-	err := c.Control(func(fd uintptr) {
-		opErr = unix.SetsockoptInt(int(fd), unix.SOL_SOCKET, unix.SO_REUSEPORT, 1)
-		//CloseOnExec already set by the runtime
-	})
-	if err != nil {
-		return err
-	}
-	return opErr
+	sysFd  int
+	closed atomic.Bool
+	isV4   bool
+	l      *slog.Logger
+	batch  int
 }

 func NewListener(l *slog.Logger, ip netip.Addr, port int, multi bool, batch int) (Conn, error) {
-	listen := netip.AddrPortFrom(ip, uint16(port))
-	lc := net.ListenConfig{}
+	af := unix.AF_INET6
+	if ip.Is4() {
+		af = unix.AF_INET
+	}
+	syscall.ForkLock.RLock()
+	fd, err := unix.Socket(af, unix.SOCK_DGRAM, unix.IPPROTO_UDP)
+	if err == nil {
+		unix.CloseOnExec(fd)
+	}
+	syscall.ForkLock.RUnlock()
+	if err != nil {
+		return nil, fmt.Errorf("unable to open socket: %w", err)
+	}
+
 	if multi {
-		lc.Control = setReusePort
-	}
-	//this context is only used during the bind operation, you can't cancel it to kill the socket
-	pc, err := lc.ListenPacket(context.Background(), "udp", listen.String())
-	if err != nil {
-		return nil, fmt.Errorf("unable to open socket: %s", err)
-	}
-	udpConn := pc.(*net.UDPConn)
-	rawConn, err := udpConn.SyscallConn()
-	if err != nil {
-		_ = udpConn.Close()
-		return nil, err
-	}
-	//gotta find out if we got an AF_INET6 socket or not:
-	out := &StdConn{
-		udpConn: udpConn,
-		rawConn: rawConn,
-		l:       l,
-		batch:   batch,
+		if err = unix.SetsockoptInt(fd, unix.SOL_SOCKET, unix.SO_REUSEPORT, 1); err != nil {
+			_ = unix.Close(fd)
+			return nil, fmt.Errorf("unable to set SO_REUSEPORT: %w", err)
+		}
 	}

-	af, err := out.getSockOptInt(unix.SO_DOMAIN)
-	if err != nil {
-		_ = out.Close()
-		return nil, err
+	var sa unix.Sockaddr
+	if ip.Is4() {
+		sa4 := &unix.SockaddrInet4{Port: port}
+		sa4.Addr = ip.As4()
+		sa = sa4
+	} else {
+		sa6 := &unix.SockaddrInet6{Port: port}
+		sa6.Addr = ip.As16()
+		sa = sa6
+	}
+	if err = unix.Bind(fd, sa); err != nil {
+		_ = unix.Close(fd)
+		return nil, fmt.Errorf("unable to bind to socket: %w", err)
 	}
-	out.isV4 = af == unix.AF_INET

-	return out, nil
+	return &StdConn{sysFd: fd, isV4: ip.Is4(), l: l, batch: batch}, nil
 }

 func (u *StdConn) SupportsMultipleReaders() bool {
@@ -81,134 +75,111 @@ func (u *StdConn) Rebind() error {
 	return nil
 }

-func (u *StdConn) getSockOptInt(opt int) (int, error) {
-	if u.rawConn == nil {
-		return 0, fmt.Errorf("no UDP connection")
-	}
-	var out int
-	var opErr error
-	err := u.rawConn.Control(func(fd uintptr) {
-		out, opErr = unix.GetsockoptInt(int(fd), unix.SOL_SOCKET, opt)
-	})
-	if err != nil {
-		return 0, err
-	}
-	return out, opErr
-}
-
-func (u *StdConn) setSockOptInt(opt int, n int) error {
-	if u.rawConn == nil {
-		return fmt.Errorf("no UDP connection")
-	}
-	var opErr error
-	err := u.rawConn.Control(func(fd uintptr) {
-		opErr = unix.SetsockoptInt(int(fd), unix.SOL_SOCKET, opt, n)
-	})
-	if err != nil {
-		return err
-	}
-	return opErr
-}
-
 func (u *StdConn) SetRecvBuffer(n int) error {
-	return u.setSockOptInt(unix.SO_RCVBUFFORCE, n)
+	return unix.SetsockoptInt(u.sysFd, unix.SOL_SOCKET, unix.SO_RCVBUFFORCE, n)
 }

 func (u *StdConn) SetSendBuffer(n int) error {
-	return u.setSockOptInt(unix.SO_SNDBUFFORCE, n)
+	return unix.SetsockoptInt(u.sysFd, unix.SOL_SOCKET, unix.SO_SNDBUFFORCE, n)
 }

 func (u *StdConn) SetSoMark(mark int) error {
-	return u.setSockOptInt(unix.SO_MARK, mark)
+	return unix.SetsockoptInt(u.sysFd, unix.SOL_SOCKET, unix.SO_MARK, mark)
 }

 func (u *StdConn) GetRecvBuffer() (int, error) {
-	return u.getSockOptInt(unix.SO_RCVBUF)
+	return unix.GetsockoptInt(u.sysFd, unix.SOL_SOCKET, unix.SO_RCVBUF)
 }

 func (u *StdConn) GetSendBuffer() (int, error) {
-	return u.getSockOptInt(unix.SO_SNDBUF)
+	return unix.GetsockoptInt(u.sysFd, unix.SOL_SOCKET, unix.SO_SNDBUF)
 }

 func (u *StdConn) GetSoMark() (int, error) {
-	return u.getSockOptInt(unix.SO_MARK)
+	return unix.GetsockoptInt(u.sysFd, unix.SOL_SOCKET, unix.SO_MARK)
 }

 func (u *StdConn) LocalAddr() (netip.AddrPort, error) {
-	a := u.udpConn.LocalAddr()
-
-	switch v := a.(type) {
-	case *net.UDPAddr:
-		addr, ok := netip.AddrFromSlice(v.IP)
-		if !ok {
-			return netip.AddrPort{}, fmt.Errorf("LocalAddr returned invalid IP address: %s", v.IP)
-		}
-		return netip.AddrPortFrom(addr, uint16(v.Port)), nil
-
+	sa, err := unix.Getsockname(u.sysFd)
+	if err != nil {
+		return netip.AddrPort{}, err
+	}
+	switch sa := sa.(type) {
+	case *unix.SockaddrInet4:
+		return netip.AddrPortFrom(netip.AddrFrom4(sa.Addr), uint16(sa.Port)), nil
+	case *unix.SockaddrInet6:
+		return netip.AddrPortFrom(netip.AddrFrom16(sa.Addr), uint16(sa.Port)), nil
 	default:
-		return netip.AddrPort{}, fmt.Errorf("LocalAddr returned: %#v", a)
+		return netip.AddrPort{}, fmt.Errorf("unsupported sock type: %T", sa)
 	}
 }

-func recvmmsg(fd uintptr, msgs []rawMessage) (int, bool, error) {
-	var errno syscall.Errno
-	n, _, errno := unix.Syscall6(
+// recvmmsg does one blocking recvmmsg (MSG_WAITFORONE), reading up to len(msgs) datagrams
+func (u *StdConn) recvmmsg(msgs []rawMessage) (int, error) {
+	r, _, errno := unix.Syscall6(
 		unix.SYS_RECVMMSG,
-		fd,
+		uintptr(u.sysFd),
 		uintptr(unsafe.Pointer(&msgs[0])),
 		uintptr(len(msgs)),
 		unix.MSG_WAITFORONE,
 		0,
 		0,
 	)
-	if errno == syscall.EAGAIN || errno == syscall.EWOULDBLOCK {
-		// No data available, block for I/O and try again.
-		return int(n), false, nil
-	}
 	if errno != 0 {
-		return int(n), true, &net.OpError{Op: "recvmmsg", Err: errno}
-	}
-	return int(n), true, nil
-}
-
-func (u *StdConn) listenOutSingle(r EncReader) error {
-	var err error
-	var n int
-	var from netip.AddrPort
-	buffer := make([]byte, MTU)
-
-	for {
-		n, from, err = u.udpConn.ReadFromUDPAddrPort(buffer)
-		if err != nil {
-			return err
+		if u.closed.Load() {
+			return 0, net.ErrClosed
 		}
-		from = netip.AddrPortFrom(from.Addr().Unmap(), from.Port())
-		r(from, buffer[:n])
+		return 0, &net.OpError{Op: "recvmmsg", Err: errno}
 	}
+	n := int(r)
+	if (n == 0 || msgs[0].Len == 0) && u.closed.Load() {
+		return 0, net.ErrClosed
+	}
+	return n, nil
 }

-func (u *StdConn) listenOutBatch(r EncReader) error {
+// recvmsg does one blocking recvmsg into msgs[0]
+func (u *StdConn) recvmsg(msgs []rawMessage) (int, error) {
+	r, _, errno := unix.Syscall6(
+		unix.SYS_RECVMSG,
+		uintptr(u.sysFd),
+		uintptr(unsafe.Pointer(&msgs[0].Hdr)),
+		0,
+		0,
+		0,
+		0,
+	)
+	if errno != 0 {
+		if u.closed.Load() {
+			return 0, net.ErrClosed
+		}
+		return 0, &net.OpError{Op: "recvmsg", Err: errno}
+	}
+	if r == 0 && u.closed.Load() {
+		return 0, net.ErrClosed
+	}
+	msgs[0].Len = uint32(r)
+	return 1, nil
+}
+
+func (u *StdConn) ListenOut(r EncReader) error {
 	var ip netip.Addr
-	var n int
-	var operr error
-
 	msgs, buffers, names := u.PrepareRawMessages(u.batch)
-
-	//reader needs to capture variables from this function, since it's used as a lambda with rawConn.Read
-	//defining it outside the loop so it gets re-used
-	reader := func(fd uintptr) (done bool) {
-		n, done, operr = recvmmsg(fd, msgs)
-		return done
+	read := u.recvmmsg
+	if u.batch == 1 {
+		read = u.recvmsg
 	}

 	for {
-		err := u.rawConn.Read(reader)
+		n, err := read(msgs)
 		if err != nil {
+			if errors.Is(err, unix.EINTR) {
+				continue // interrupted by a signal, retry the read
+			}
+			// net.ErrClosed after Close() is teardown, absorbed by the caller's
+			// closed flag like the other platforms; anything else is a real error.
 			return err
 		}
-		if operr != nil {
-			return operr
-		}

 		for i := 0; i < n; i++ {
 			// Its ok to skip the ok check here, the slicing is the only error that can occur and it will panic
@@ -222,26 +193,68 @@ func (u *StdConn) listenOutBatch(r EncReader) error {
 	}
 }

-func (u *StdConn) ListenOut(r EncReader) error {
-	if u.batch == 1 {
-		return u.listenOutSingle(r)
-	} else {
-		return u.listenOutBatch(r)
+func (u *StdConn) WriteTo(b []byte, ip netip.AddrPort) error {
+	if u.isV4 {
+		return u.writeTo4(b, ip)
+	}
+	return u.writeTo6(b, ip)
+}
+
+func (u *StdConn) writeTo6(b []byte, ip netip.AddrPort) error {
+	var rsa unix.RawSockaddrInet6
+	rsa.Family = unix.AF_INET6
+	rsa.Addr = ip.Addr().As16()
+	binary.BigEndian.PutUint16((*[2]byte)(unsafe.Pointer(&rsa.Port))[:], ip.Port())
+
+	for {
+		_, _, err := unix.Syscall6(
+			unix.SYS_SENDTO,
+			uintptr(u.sysFd),
+			uintptr(unsafe.Pointer(&b[0])),
+			uintptr(len(b)),
+			uintptr(0),
+			uintptr(unsafe.Pointer(&rsa)),
+			uintptr(unix.SizeofSockaddrInet6),
+		)
+		if err != 0 {
+			return &net.OpError{Op: "sendto", Err: err}
+		}
+		return nil
 	}
 }

-func (u *StdConn) WriteTo(b []byte, ip netip.AddrPort) error {
-	_, err := u.udpConn.WriteToUDPAddrPort(b, ip)
-	return err
+func (u *StdConn) writeTo4(b []byte, ip netip.AddrPort) error {
+	if !ip.Addr().Is4() {
+		return ErrInvalidIPv6RemoteForSocket
+	}
+
+	var rsa unix.RawSockaddrInet4
+	rsa.Family = unix.AF_INET
+	rsa.Addr = ip.Addr().As4()
+	binary.BigEndian.PutUint16((*[2]byte)(unsafe.Pointer(&rsa.Port))[:], ip.Port())
+
+	for {
+		_, _, err := unix.Syscall6(
+			unix.SYS_SENDTO,
+			uintptr(u.sysFd),
+			uintptr(unsafe.Pointer(&b[0])),
+			uintptr(len(b)),
+			uintptr(0),
+			uintptr(unsafe.Pointer(&rsa)),
+			uintptr(unix.SizeofSockaddrInet4),
+		)
+		if err != 0 {
+			return &net.OpError{Op: "sendto", Err: err}
+		}
+		return nil
+	}
 }

 func (u *StdConn) ReloadConfig(c *config.C) {
 	b := c.GetInt("listen.read_buffer", 0)
 	if b > 0 {
-		err := u.SetRecvBuffer(b)
-		if err == nil {
-			s, err := u.GetRecvBuffer()
-			if err == nil {
+		if err := u.SetRecvBuffer(b); err == nil {
+			if s, err := u.GetRecvBuffer(); err == nil {
 				u.l.Info("listen.read_buffer was set", "size", s)
 			} else {
 				u.l.Warn("Failed to get listen.read_buffer", "error", err)
@@ -253,10 +266,8 @@ func (u *StdConn) ReloadConfig(c *config.C) {

 	b = c.GetInt("listen.write_buffer", 0)
 	if b > 0 {
-		err := u.SetSendBuffer(b)
-		if err == nil {
-			s, err := u.GetSendBuffer()
-			if err == nil {
+		if err := u.SetSendBuffer(b); err == nil {
+			if s, err := u.GetSendBuffer(); err == nil {
 				u.l.Info("listen.write_buffer was set", "size", s)
 			} else {
 				u.l.Warn("Failed to get listen.write_buffer", "error", err)
@@ -269,10 +280,8 @@ func (u *StdConn) ReloadConfig(c *config.C) {
 	b = c.GetInt("listen.so_mark", 0)
 	s, err := u.GetSoMark()
 	if b > 0 || (err == nil && s != 0) {
-		err := u.SetSoMark(b)
-		if err == nil {
-			s, err := u.GetSoMark()
-			if err == nil {
+		if err := u.SetSoMark(b); err == nil {
+			if s, err := u.GetSoMark(); err == nil {
 				u.l.Info("listen.so_mark was set", "mark", s)
 			} else {
 				u.l.Warn("Failed to get listen.so_mark", "error", err)
@@ -285,28 +294,20 @@ func (u *StdConn) ReloadConfig(c *config.C) {

 func (u *StdConn) getMemInfo(meminfo *[unix.SK_MEMINFO_VARS]uint32) error {
 	var vallen uint32 = 4 * unix.SK_MEMINFO_VARS
-
-	if u.rawConn == nil {
-		return fmt.Errorf("no UDP connection")
-	}
-	var opErr error
-	err := u.rawConn.Control(func(fd uintptr) {
-		_, _, syserr := unix.Syscall6(unix.SYS_GETSOCKOPT, fd, uintptr(unix.SOL_SOCKET), uintptr(unix.SO_MEMINFO), uintptr(unsafe.Pointer(meminfo)), uintptr(unsafe.Pointer(&vallen)), 0)
-		if syserr != 0 {
-			opErr = syserr
-		}
-	})
-	if err != nil {
+	_, _, err := unix.Syscall6(unix.SYS_GETSOCKOPT, uintptr(u.sysFd), uintptr(unix.SOL_SOCKET), uintptr(unix.SO_MEMINFO), uintptr(unsafe.Pointer(meminfo)), uintptr(unsafe.Pointer(&vallen)), 0)
+	if err != 0 {
 		return err
 	}
-	return opErr
+	return nil
 }

 func (u *StdConn) Close() error {
-	if u.udpConn != nil {
-		return u.udpConn.Close()
-	}
-	return nil
+	u.closed.Store(true)
+	// Wake the reader parked in recvmmsg/recvmsg. shutdown(2) on an unconnected socket
+	// returns ENOTCONN but still wakes it, so ignore the error.
+	// The reader then sees closed and stops touching the fd, making the Close below safe.
+	_ = unix.Shutdown(u.sysFd, unix.SHUT_RDWR)
+	return unix.Close(u.sysFd)
 }

 func NewUDPStatsEmitter(udpConns []Conn) func() {
@@ -0,0 +1,179 @@
+//go:build linux && !android && !e2e_testing
+
+package udp
+
+import (
+	"errors"
+	"fmt"
+	"log/slog"
+	"net"
+	"net/netip"
+	"os"
+	"runtime"
+	"sync/atomic"
+	"testing"
+	"time"
+
+	"golang.org/x/sys/unix"
+)
+
+func testLogger() *slog.Logger {
+	return slog.New(slog.NewTextHandler(os.Stderr, &slog.HandlerOptions{Level: slog.LevelError}))
+}
+
+// TestShutdownWakesAfterRx_Mechanism exercises the kernel quirk our teardown
+// relies on: once a socket has received a packet, shutdown(2) wakes a blocked
+// recvmmsg with n>=1/Len==0 (not n==0). recvmmsg must turn that into net.ErrClosed
+// once Close set closed, so a parked reader exits instead of spinning.
+func TestShutdownWakesAfterRx_Mechanism(t *testing.T) {
+	c, err := NewListener(testLogger(), netip.MustParseAddr("127.0.0.1"), 0, true, 64)
+	if err != nil {
+		t.Fatalf("NewListener: %v", err)
+	}
+	sc := c.(*StdConn)
+	addr, err := sc.LocalAddr()
+	if err != nil {
+		t.Fatalf("LocalAddr: %v", err)
+	}
+	msgs, _, _ := sc.PrepareRawMessages(sc.batch)
+
+	// Receive a real packet so the socket has carried data.
+	send, err := net.Dial("udp", addr.String())
+	if err != nil {
+		t.Fatalf("dial: %v", err)
+	}
+	if _, err := send.Write([]byte("hello")); err != nil {
+		t.Fatalf("write: %v", err)
+	}
+	time.Sleep(50 * time.Millisecond)
+	n, err := sc.recvmmsg(msgs)
+	t.Logf("drain of real packet: n=%d err=%v msgs[0].Len=%d", n, err, msgs[0].Len)
+	_ = send.Close()
+
+	// Block a reader on the now-empty queue, then tear down as Close() does.
+	// recvmmsg must return net.ErrClosed (not hang, not spin) even post-rx.
+	done := make(chan error, 1)
+	go func() {
+		_, err := sc.recvmmsg(msgs)
+		done <- err
+	}()
+	time.Sleep(150 * time.Millisecond) // let it park in recvmmsg
+
+	sc.closed.Store(true)
+	if serr := unix.Shutdown(sc.sysFd, unix.SHUT_RDWR); serr != nil {
+		t.Logf("shutdown returned %v (expected ENOTCONN on unconnected UDP)", serr)
+	}
+
+	select {
+	case err := <-done:
+		if !errors.Is(err, net.ErrClosed) {
+			t.Errorf("recvmmsg after post-rx shutdown returned %v, want net.ErrClosed", err)
+		}
+	case <-time.After(2 * time.Second):
+		t.Fatalf("HANG: recvmmsg did not return after shutdown following a received packet")
+	}
+	_ = unix.Close(sc.sysFd)
+}
+
+// TestListenOutTeardown_TrafficPatterns reproduces the field report: a blocking
+// reader must tear down cleanly on Close() regardless of what the socket has
+// carried. The three cases the report called out:
+//
+//	no traffic ever      -> works (shutdown wakes recvmmsg with n==0)
+//	ping once, then idle -> historically HUNG: once the socket has received a
+//	                        packet, shutdown(2) wakes recvmmsg with n>=1/Len==0,
+//	                        which an n==0-only teardown check misses
+//	continuous traffic   -> works (a real packet is always arriving)
+//
+// All three must return within the deadline; a hang dumps goroutines so the
+// stuck reader is visible.
+func TestListenOutTeardown_TrafficPatterns(t *testing.T) {
+	cases := []struct {
+		name    string
+		traffic func(send net.Conn, stop <-chan struct{})
+	}{
+		{"no_traffic_ever", func(net.Conn, <-chan struct{}) {}},
+		{"ping_once_then_idle", func(send net.Conn, _ <-chan struct{}) {
+			_, _ = send.Write([]byte("hello"))
+		}},
+		{"continuous", func(send net.Conn, stop <-chan struct{}) {
+			for {
+				select {
+				case <-stop:
+					return
+				default:
+					_, _ = send.Write([]byte("hello"))
+					time.Sleep(2 * time.Millisecond)
+				}
+			}
+		}},
+	}
+
+	// batch 1 exercises the recvmsg path, batch 64 the recvmmsg path; both must
+	// tear down cleanly.
+	for _, batch := range []int{1, 64} {
+		for _, tc := range cases {
+			t.Run(fmt.Sprintf("batch%d/%s", batch, tc.name), func(t *testing.T) {
+				runTeardownCase(t, batch, tc.name, tc.traffic)
+			})
+		}
+	}
+}
+
+func runTeardownCase(t *testing.T, batch int, name string, traffic func(send net.Conn, stop <-chan struct{})) {
+	c, err := NewListener(testLogger(), netip.MustParseAddr("127.0.0.1"), 0, true, batch)
+	if err != nil {
+		t.Fatalf("NewListener: %v", err)
+	}
+	sc := c.(*StdConn)
+	addr, err := sc.LocalAddr()
+	if err != nil {
+		t.Fatalf("LocalAddr: %v", err)
+	}
+
+	var received atomic.Int64
+	loopDone := make(chan error, 1)
+	go func() {
+		loopDone <- sc.ListenOut(func(netip.AddrPort, []byte) {
+			received.Add(1)
+		})
+	}()
+
+	send, err := net.Dial("udp", addr.String())
+	if err != nil {
+		t.Fatalf("dial: %v", err)
+	}
+	defer send.Close()
+
+	stop := make(chan struct{})
+	trafficDone := make(chan struct{})
+	go func() {
+		traffic(send, stop)
+		close(trafficDone)
+	}()
+
+	// Let the pattern run and, for the idle case, the reader park again on an
+	// empty queue with the socket already having received a packet.
+	time.Sleep(500 * time.Millisecond)
+
+	start := time.Now()
+	if err := sc.Close(); err != nil {
+		t.Fatalf("Close: %v", err)
+	}
+	close(stop)
+
+	select {
+	case err := <-loopDone:
+		// Clean teardown surfaces as net.ErrClosed (propagated like the other
+		// platforms); the caller absorbs it via its closed flag.
+		if err != nil && !errors.Is(err, net.ErrClosed) {
+			t.Fatalf("%s: ListenOut returned unexpected error on teardown: %v", name, err)
+		}
+		t.Logf("%s: closed in %v (received %d packets)", name, time.Since(start), received.Load())
+	case <-time.After(3 * time.Second):
+		buf := make([]byte, 1<<20)
+		n := runtime.Stack(buf, true)
+		t.Fatalf("%s: HANG, ListenOut did not return within 3s of Close\n%s", name, buf[:n])
+	}
+	<-trafficDone
+}
@@ -0,0 +1,29 @@
+//go:build darwin
+
+package nebula
+
+import (
+	"time"
+
+	"golang.org/x/sys/unix"
+)
+
+// suspendClockDelta returns CLOCK_MONOTONIC - CLOCK_UPTIME_RAW. On macOS CLOCK_MONOTONIC keeps counting across
+// system sleep while CLOCK_UPTIME_RAW (mach_absolute_time) pauses, so the difference grows by time spent asleep.
+//
+// The pausing clock is read first so scheduling jitter between the two reads biases the delta positive; the
+// wakeDetector clamps out the noise.
+//
+// Caveat: on Apple Silicon the hardware timebase keeps ticking through sleep, which can make both clocks advance
+// and the spread stay flat, leaving this detector blind. That fails safe (no clears, behavior as before); IOKit
+// power notifications are the follow-up for full coverage on those machines.
+func suspendClockDelta() (time.Duration, bool) {
+	var uptime, mono unix.Timespec
+	if err := unix.ClockGettime(unix.CLOCK_UPTIME_RAW, &uptime); err != nil {
+		return 0, false
+	}
+	if err := unix.ClockGettime(unix.CLOCK_MONOTONIC, &mono); err != nil {
+		return 0, false
+	}
+	return time.Duration(mono.Nano() - uptime.Nano()), true
+}
@@ -0,0 +1,11 @@
+//go:build !linux && !darwin && !windows
+
+package nebula
+
+import "time"
+
+// suspendClockDelta reports that this platform has no usable clock pair for detecting system sleep; the wake
+// detector stays dormant and dead tunnels are left to the normal traffic checks.
+func suspendClockDelta() (time.Duration, bool) {
+	return 0, false
+}
@@ -0,0 +1,26 @@
+//go:build linux
+
+package nebula
+
+import (
+	"time"
+
+	"golang.org/x/sys/unix"
+)
+
+// suspendClockDelta returns CLOCK_BOOTTIME - CLOCK_MONOTONIC. CLOCK_MONOTONIC pauses while the system is suspended
+// and CLOCK_BOOTTIME does not, so the difference only ever grows, and only by time spent suspended. Both reads are
+// vDSO calls, cheap enough for a hot ticker.
+//
+// The pausing clock is read first so scheduling jitter between the two reads biases the delta positive; the
+// wakeDetector clamps out the noise.
+func suspendClockDelta() (time.Duration, bool) {
+	var mono, boot unix.Timespec
+	if err := unix.ClockGettime(unix.CLOCK_MONOTONIC, &mono); err != nil {
+		return 0, false
+	}
+	if err := unix.ClockGettime(unix.CLOCK_BOOTTIME, &boot); err != nil {
+		return 0, false
+	}
+	return time.Duration(boot.Nano() - mono.Nano()), true
+}
@@ -0,0 +1,41 @@
+//go:build windows
+
+package nebula
+
+import (
+	"sync"
+	"time"
+	"unsafe"
+
+	"golang.org/x/sys/windows"
+)
+
+var (
+	procQueryInterruptTime         = windows.NewLazySystemDLL("kernelbase.dll").NewProc("QueryInterruptTime")
+	procQueryUnbiasedInterruptTime = windows.NewLazySystemDLL("kernel32.dll").NewProc("QueryUnbiasedInterruptTime")
+
+	// QueryInterruptTime needs Windows 10; probe once and stay dormant on anything older.
+	wakeClockAvailable = sync.OnceValue(func() bool {
+		return procQueryInterruptTime.Find() == nil && procQueryUnbiasedInterruptTime.Find() == nil
+	})
+)
+
+// suspendClockDelta returns interrupt time minus unbiased interrupt time, both in 100ns units. The unbiased count
+// excludes time the system spends suspended while the biased one includes it, so the difference grows by exactly
+// the time spent asleep.
+//
+// The pausing (unbiased) clock is read first so scheduling jitter between the two reads biases the delta positive;
+// the wakeDetector clamps out the noise.
+func suspendClockDelta() (time.Duration, bool) {
+	if !wakeClockAvailable() {
+		return 0, false
+	}
+
+	var unbiased, biased uint64
+	if r1, _, _ := procQueryUnbiasedInterruptTime.Call(uintptr(unsafe.Pointer(&unbiased))); r1 == 0 {
+		return 0, false
+	}
+	// Returns void, cannot fail once resolved.
+	_, _, _ = procQueryInterruptTime.Call(uintptr(unsafe.Pointer(&biased)))
+	return time.Duration(int64(biased-unbiased)) * 100, true
+}
@@ -0,0 +1,47 @@
+package nebula
+
+import "time"
+
+// wakeDetector notices when the machine has returned from system sleep and measures how long it was suspended.
+//
+// It samples the spread between two kernel clocks: one that pauses across a suspend and one that keeps counting
+// (suspendClockDelta, per platform). While the machine is awake the spread is constant no matter how starved,
+// stopped, or stepped this process is — SIGSTOP, debugger pauses, scheduler starvation, and NTP adjustments move
+// both clocks together or neither, so none of them can fake a wake. A true suspend is the only thing that grows
+// the spread, and it grows by exactly the time spent suspended.
+//
+// Sample is intended to piggyback on a ticker the caller already runs; it costs two clock reads. It is not safe
+// for concurrent use.
+type wakeDetector struct {
+	// read returns the current spread between the two clocks, false if this platform can't provide one.
+	read   func() (time.Duration, bool)
+	last   time.Duration
+	primed bool
+}
+
+func newWakeDetector() *wakeDetector {
+	return &wakeDetector{read: suspendClockDelta}
+}
+
+// Sample returns how long the machine was suspended since the previous call, 0 if it wasn't, and false if the
+// platform has no way to tell. The first call primes the baseline and always reports 0.
+func (w *wakeDetector) Sample() (time.Duration, bool) {
+	delta, ok := w.read()
+	if !ok {
+		return 0, false
+	}
+
+	if !w.primed {
+		w.primed = true
+		w.last = delta
+		return 0, true
+	}
+
+	slept := delta - w.last
+	w.last = delta
+	if slept < 0 {
+		// The clock pair is read non-atomically so tiny negative jitter is possible; it is never a wake.
+		slept = 0
+	}
+	return slept, true
+}
@@ -0,0 +1,67 @@
+package nebula
+
+import (
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestWakeDetector(t *testing.T) {
+	delta := time.Duration(0)
+	ok := true
+	w := &wakeDetector{read: func() (time.Duration, bool) { return delta, ok }}
+
+	// The first sample primes the baseline and never reports a wake, even with a pre-existing spread
+	delta = 3 * time.Hour
+	slept, sok := w.Sample()
+	assert.True(t, sok)
+	assert.Equal(t, time.Duration(0), slept)
+
+	// A stable spread means the machine never slept
+	slept, sok = w.Sample()
+	assert.True(t, sok)
+	assert.Equal(t, time.Duration(0), slept)
+
+	// The spread grows by exactly the time spent suspended
+	delta += 42 * time.Second
+	slept, sok = w.Sample()
+	assert.True(t, sok)
+	assert.Equal(t, 42*time.Second, slept)
+
+	// A wake is reported once, then the baseline moves with it
+	slept, sok = w.Sample()
+	assert.True(t, sok)
+	assert.Equal(t, time.Duration(0), slept)
+
+	// Negative jitter from the non-atomic clock pair reads clamps to zero
+	delta -= time.Microsecond
+	slept, sok = w.Sample()
+	assert.True(t, sok)
+	assert.Equal(t, time.Duration(0), slept)
+
+	// Consecutive suspends both report; the clamped jitter moved the baseline so it is not double-counted
+	delta += time.Minute
+	slept, _ = w.Sample()
+	assert.Equal(t, time.Minute, slept)
+	delta += time.Hour
+	slept, _ = w.Sample()
+	assert.Equal(t, time.Hour, slept)
+
+	// An unsupported platform read reports not-ok
+	ok = false
+	_, sok = w.Sample()
+	assert.False(t, sok)
+}
+
+// TestWakeDetectorPlatformClock smoke tests the real clock pair: two samples close together must not report a
+// wake on a machine that isn't suspending mid-test.
+func TestWakeDetectorPlatformClock(t *testing.T) {
+	w := newWakeDetector()
+	if _, ok := w.Sample(); !ok {
+		t.Skip("platform has no suspend clock pair")
+	}
+	slept, ok := w.Sample()
+	assert.True(t, ok)
+	assert.Less(t, slept, time.Second)
+}
Author	SHA1	Message	Date
JackDoan	c8a3994cde	wakey wakey	2026-07-22 18:49:19 -05:00
Nate Brown	c2fbe215e6	Fix a test race, make dns server reload/restart safer (#1815 ) smoke-extra / freebsd-amd64 (push) Failing after 54s Details smoke-extra / linux-amd64-ipv6disable (push) Failing after 11s Details smoke-extra / netbsd-amd64 (push) Failing after 11s Details smoke-extra / openbsd-amd64 (push) Failing after 22s Details smoke-extra / linux-386 (push) Failing after 23s Details smoke / Run multi node smoke test (push) Failing after 1m26s Details Build and test / Static checks (push) Successful in 2m11s Details Build and test / Test linux (push) Failing after 1m7s Details Build and test / Test linux-boringcrypto (push) Failing after 2m41s Details Build and test / Test linux-pkcs11 (push) Failing after 2m2s Details Build and test / Cross-build linux-arm (push) Successful in 3m5s Details Build and test / Cross-build linux-mips (push) Successful in 3m48s Details Build and test / Cross-build linux-other (push) Successful in 3m8s Details Build and test / Cross-build windows (push) Successful in 1m4s Details Build and test / Cross-build freebsd (push) Successful in 1m36s Details Build and test / Cross-build netbsd (push) Successful in 1m33s Details Build and test / Cross-build openbsd (push) Successful in 1m32s Details Build and test / Cross-build mobile (push) Successful in 3m16s Details smoke-extra / Run windows smoke test (push) Has been cancelled Details Build and test / Test macos (push) Has been cancelled Details Build and test / Test windows (push) Has been cancelled Details Build and test / CI status (push) Has been cancelled Details	2026-07-22 15:05:10 -05:00
dependabot[bot]	94ac6db4ca	Bump the golang-x-dependencies group across 1 directory with 5 updates (#1800 ) Bumps the golang-x-dependencies group with 3 updates in the / directory: [golang.org/x/crypto](https://github.com/golang/crypto), [golang.org/x/net](https://github.com/golang/net) and [golang.org/x/sync](https://github.com/golang/sync). Updates `golang.org/x/crypto` from 0.53.0 to 0.54.0 - [Commits](https://github.com/golang/crypto/compare/v0.53.0...v0.54.0) Updates `golang.org/x/net` from 0.56.0 to 0.57.0 - [Commits](https://github.com/golang/net/compare/v0.56.0...v0.57.0) Updates `golang.org/x/sync` from 0.21.0 to 0.22.0 - [Commits](https://github.com/golang/sync/compare/v0.21.0...v0.22.0) Updates `golang.org/x/sys` from 0.46.0 to 0.47.0 - [Commits](https://github.com/golang/sys/compare/v0.46.0...v0.47.0) Updates `golang.org/x/term` from 0.44.0 to 0.45.0 - [Commits](https://github.com/golang/term/compare/v0.44.0...v0.45.0) --- updated-dependencies: - dependency-name: golang.org/x/crypto dependency-version: 0.54.0 dependency-type: direct:production update-type: version-update:semver-minor dependency-group: golang-x-dependencies - dependency-name: golang.org/x/net dependency-version: 0.57.0 dependency-type: direct:production update-type: version-update:semver-minor dependency-group: golang-x-dependencies - dependency-name: golang.org/x/sync dependency-version: 0.22.0 dependency-type: direct:production update-type: version-update:semver-minor dependency-group: golang-x-dependencies - dependency-name: golang.org/x/sys dependency-version: 0.47.0 dependency-type: direct:production update-type: version-update:semver-minor dependency-group: golang-x-dependencies - dependency-name: golang.org/x/term dependency-version: 0.45.0 dependency-type: direct:production update-type: version-update:semver-minor dependency-group: golang-x-dependencies ... Signed-off-by: dependabot[bot] <support@github.com> Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>	2026-07-22 15:51:22 -04:00
dependabot[bot]	a60350e34e	Bump actions/setup-go from 6 to 7 (#1807 ) Bumps [actions/setup-go](https://github.com/actions/setup-go) from 6 to 7. - [Release notes](https://github.com/actions/setup-go/releases) - [Commits](https://github.com/actions/setup-go/compare/v6...v7) --- updated-dependencies: - dependency-name: actions/setup-go dependency-version: '7' dependency-type: direct:production update-type: version-update:semver-major ... Signed-off-by: dependabot[bot] <support@github.com> Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>	2026-07-22 15:49:45 -04:00
John Maguire	58f3b6fda7	Document rootless Nebula in example service script (#1814 )	2026-07-21 19:32:33 -04:00
Jack Doan	a99699e370	before removing a pending hostinfo in handshake_manager, make sure it's the one we wanted to delete (#1811 )	2026-07-21 10:31:00 -05:00
Jack Doan	3615a79b8b	add locks around replay window updates (#1802 )	2026-07-20 10:28:53 -05:00
Nate Brown	147c202c27	Swap back to a blocking udp socket, test `shutdown(2)` (#1806 ) Co-authored-by: Jack Doan <me@jackdoan.com>	2026-07-17 15:16:45 -05:00
John Maguire	e290a6892f	Fix relay re-establishment for handshake on Disestablised entry (#1805 ) handleOutsideRelayPacket filled ViaSender.remoteIdx with relay.RemoteIndex, an index from the relay peer's index space, but the rescue in sendHandshakeResponse looks that value up in relayForByIdx, which is keyed by local index. The lookup could never hit, so a terminal relay entry left Disestablished by a one-sided teardown stayed Disestablished even after a valid handshake arrived over it. The responder's first transmit then failed to find an Established relay, deleted its only relay entry, and every subsequent send was silently dropped until dead-tunnel detection forced a re-handshake.	2026-07-17 11:57:47 -04:00
Nate Brown	6c3972f464	code-sign: default the S3 key-prefix to the calling repo (#1799 )	2026-07-13 11:49:59 -05:00
Jack Doan	861d3aabd7	correct directionality of firewall.inbound_action and firewall.outbound_action (#1798 )	2026-07-13 08:40:42 -05:00