firewall can distinguish if the host connecting has an overlapping network, is a VPN peer without an overlapping network, or is a unsafe network

e2e/helpers_test.go

@@ -29,8 +29,6 @@ type m = map[string]any
 
 // newSimpleServer creates a nebula instance with many assumptions
 func newSimpleServer(v cert.Version, caCrt cert.Certificate, caKey []byte, name string, sVpnNetworks string, overrides m) (*nebula.Control, []netip.Prefix, netip.AddrPort, *config.C) {
-	l := NewTestLogger()
-
 	var vpnNetworks []netip.Prefix
 	for _, sn := range strings.Split(sVpnNetworks, ",") {
 		vpnIpNet, err := netip.ParsePrefix(strings.TrimSpace(sn))
@@ -56,6 +54,25 @@ func newSimpleServer(v cert.Version, caCrt cert.Certificate, caKey []byte, name
 		budpIp[3] = 239
 		udpAddr = netip.AddrPortFrom(netip.AddrFrom16(budpIp), 4242)
 	}
+	return newSimpleServerWithUdp(v, caCrt, caKey, name, sVpnNetworks, udpAddr, overrides)
+}
+
+func newSimpleServerWithUdp(v cert.Version, caCrt cert.Certificate, caKey []byte, name string, sVpnNetworks string, udpAddr netip.AddrPort, overrides m) (*nebula.Control, []netip.Prefix, netip.AddrPort, *config.C) {
+	l := NewTestLogger()
+
+	var vpnNetworks []netip.Prefix
+	for _, sn := range strings.Split(sVpnNetworks, ",") {
+		vpnIpNet, err := netip.ParsePrefix(strings.TrimSpace(sn))
+		if err != nil {
+			panic(err)
+		}
+		vpnNetworks = append(vpnNetworks, vpnIpNet)
+	}
+
+	if len(vpnNetworks) == 0 {
+		panic("no vpn networks")
+	}
+
 	_, _, myPrivKey, myPEM := cert_test.NewTestCert(v, cert.Curve_CURVE25519, caCrt, caKey, name, time.Now(), time.Now().Add(5*time.Minute), vpnNetworks, nil, []string{})
 
 	caB, err := caCrt.MarshalPEM()

e2e/tunnels_test.go

@@ -4,6 +4,7 @@
 package e2e
 
 import (
+	"net/netip"
 	"testing"
 	"time"
 
@@ -55,3 +56,50 @@ func TestDropInactiveTunnels(t *testing.T) {
 	myControl.Stop()
 	theirControl.Stop()
 }
+
+func TestCrossStackRelaysWork(t *testing.T) {
+	ca, _, caKey, _ := cert_test.NewTestCaCert(cert.Version2, cert.Curve_CURVE25519, time.Now(), time.Now().Add(10*time.Minute), nil, nil, []string{})
+	myControl, myVpnIpNet, _, _ := newSimpleServer(cert.Version2, ca, caKey, "me     ", "10.128.0.1/24,fc00::1/64", m{"relay": m{"use_relays": true}})
+	relayControl, relayVpnIpNet, relayUdpAddr, _ := newSimpleServer(cert.Version2, ca, caKey, "relay  ", "10.128.0.128/24,fc00::128/64", m{"relay": m{"am_relay": true}})
+	theirUdp := netip.MustParseAddrPort("10.0.0.2:4242")
+	theirControl, theirVpnIpNet, theirUdpAddr, _ := newSimpleServerWithUdp(cert.Version2, ca, caKey, "them   ", "fc00::2/64", theirUdp, m{"relay": m{"use_relays": true}})
+
+	//myVpnV4 := myVpnIpNet[0]
+	myVpnV6 := myVpnIpNet[1]
+	relayVpnV4 := relayVpnIpNet[0]
+	relayVpnV6 := relayVpnIpNet[1]
+	theirVpnV6 := theirVpnIpNet[0]
+
+	// Teach my how to get to the relay and that their can be reached via the relay
+	myControl.InjectLightHouseAddr(relayVpnV4.Addr(), relayUdpAddr)
+	myControl.InjectLightHouseAddr(relayVpnV6.Addr(), relayUdpAddr)
+	myControl.InjectRelays(theirVpnV6.Addr(), []netip.Addr{relayVpnV6.Addr()})
+	relayControl.InjectLightHouseAddr(theirVpnV6.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.InjectTunUDPPacket(theirVpnV6.Addr(), 80, myVpnV6.Addr(), 80, []byte("Hi from me"))
+
+	p := r.RouteForAllUntilTxTun(theirControl)
+	r.Log("Assert the tunnel works")
+	assertUdpPacket(t, []byte("Hi from me"), p, myVpnV6.Addr(), theirVpnV6.Addr(), 80, 80)
+
+	t.Log("reply?")
+	theirControl.InjectTunUDPPacket(myVpnV6.Addr(), 80, theirVpnV6.Addr(), 80, []byte("Hi from them"))
+	p = r.RouteForAllUntilTxTun(myControl)
+	assertUdpPacket(t, []byte("Hi from them"), p, theirVpnV6.Addr(), myVpnV6.Addr(), 80, 80)
+
+	r.RenderHostmaps("Final hostmaps", myControl, relayControl, theirControl)
+	//t.Log("finish up")
+	//myControl.Stop()
+	//theirControl.Stop()
+	//relayControl.Stop()
+}

firewall.go

@@ -417,6 +417,8 @@ func AddFirewallRulesFromConfig(l *logrus.Logger, inbound bool, c *config.C, fw
 	return nil
 }
 
+var ErrUnknownNetworkType = errors.New("unknown network type")
+var ErrPeerRejected = errors.New("remote IP is not within a subnet that we handle")
 var ErrInvalidRemoteIP = errors.New("remote IP is not in remote certificate subnets")
 var ErrInvalidLocalIP = errors.New("local IP is not in list of handled local IPs")
 var ErrNoMatchingRule = errors.New("no matching rule in firewall table")
@@ -429,18 +431,31 @@ func (f *Firewall) Drop(fp firewall.Packet, incoming bool, h *HostInfo, caPool *
 		return nil
 	}
 
-	// Make sure remote address matches nebula certificate
+	// Make sure remote address matches nebula certificate, and determine how to treat it
-	if h.networks != nil {
+	if h.networks == nil {
-		if !h.networks.Contains(fp.RemoteAddr) {
-			f.metrics(incoming).droppedRemoteAddr.Inc(1)
-			return ErrInvalidRemoteIP
-		}
-	} else {
 		// Simple case: Certificate has one address and no unsafe networks
 		if h.vpnAddrs[0] != fp.RemoteAddr {
 			f.metrics(incoming).droppedRemoteAddr.Inc(1)
 			return ErrInvalidRemoteIP
 		}
+	} else {
+		nwType, ok := h.networks.Lookup(fp.RemoteAddr)
+		if !ok {
+			f.metrics(incoming).droppedRemoteAddr.Inc(1)
+			return ErrInvalidRemoteIP
+		}
+		switch nwType {
+		case NetworkTypeVPN:
+			break // nothing special
+		case NetworkTypeVPNPeer:
+			f.metrics(incoming).droppedRemoteAddr.Inc(1)
+			return ErrPeerRejected // reject for now, one day this may have different FW rules
+		case NetworkTypeUnsafe:
+			break // nothing special, one day this may have different FW rules
+		default:
+			f.metrics(incoming).droppedRemoteAddr.Inc(1)
+			return ErrUnknownNetworkType //should never happen
+		}
 	}
 
 	// Make sure we are supposed to be handling this local ip address

firewall_test.go

@@ -8,6 +8,7 @@ import (
 	"testing"
 	"time"
 
+	"github.com/gaissmai/bart"
 	"github.com/slackhq/nebula/cert"
 	"github.com/slackhq/nebula/config"
 	"github.com/slackhq/nebula/firewall"
@@ -149,7 +150,8 @@ func TestFirewall_Drop(t *testing.T) {
 	l := test.NewLogger()
 	ob := &bytes.Buffer{}
 	l.SetOutput(ob)
-
+	myVpnNetworksTable := new(bart.Lite)
+	myVpnNetworksTable.Insert(netip.MustParsePrefix("1.1.1.1/8"))
 	p := firewall.Packet{
 		LocalAddr:  netip.MustParseAddr("1.2.3.4"),
 		RemoteAddr: netip.MustParseAddr("1.2.3.4"),
@@ -174,7 +176,7 @@ func TestFirewall_Drop(t *testing.T) {
 		},
 		vpnAddrs: []netip.Addr{netip.MustParseAddr("1.2.3.4")},
 	}
-	h.buildNetworks(c.networks, c.unsafeNetworks)
+	h.buildNetworks(myVpnNetworksTable, c.networks, c.unsafeNetworks)
 
 	fw := NewFirewall(l, time.Second, time.Minute, time.Hour, &c)
 	require.NoError(t, fw.AddRule(true, firewall.ProtoAny, 0, 0, []string{"any"}, "", netip.Prefix{}, netip.Prefix{}, "", ""))
@@ -226,6 +228,9 @@ func TestFirewall_DropV6(t *testing.T) {
 	ob := &bytes.Buffer{}
 	l.SetOutput(ob)
 
+	myVpnNetworksTable := new(bart.Lite)
+	myVpnNetworksTable.Insert(netip.MustParsePrefix("fd00::/7"))
+
 	p := firewall.Packet{
 		LocalAddr:  netip.MustParseAddr("fd12::34"),
 		RemoteAddr: netip.MustParseAddr("fd12::34"),
@@ -250,7 +255,7 @@ func TestFirewall_DropV6(t *testing.T) {
 		},
 		vpnAddrs: []netip.Addr{netip.MustParseAddr("fd12::34")},
 	}
-	h.buildNetworks(c.networks, c.unsafeNetworks)
+	h.buildNetworks(myVpnNetworksTable, c.networks, c.unsafeNetworks)
 
 	fw := NewFirewall(l, time.Second, time.Minute, time.Hour, &c)
 	require.NoError(t, fw.AddRule(true, firewall.ProtoAny, 0, 0, []string{"any"}, "", netip.Prefix{}, netip.Prefix{}, "", ""))
@@ -392,7 +397,7 @@ func BenchmarkFirewallTable_match(b *testing.B) {
 		c := &cert.CachedCertificate{
 			Certificate: &dummyCert{
 				name:     "nope",
-				networks: []netip.Prefix{netip.MustParsePrefix("fd99:99/128")},
+				networks: []netip.Prefix{netip.MustParsePrefix("fd99::99/128")},
 			},
 			InvertedGroups: map[string]struct{}{"nope": {}},
 		}
@@ -453,6 +458,8 @@ func TestFirewall_Drop2(t *testing.T) {
 	l := test.NewLogger()
 	ob := &bytes.Buffer{}
 	l.SetOutput(ob)
+	myVpnNetworksTable := new(bart.Lite)
+	myVpnNetworksTable.Insert(netip.MustParsePrefix("1.1.1.1/8"))
 
 	p := firewall.Packet{
 		LocalAddr:  netip.MustParseAddr("1.2.3.4"),
@@ -478,7 +485,7 @@ func TestFirewall_Drop2(t *testing.T) {
 		},
 		vpnAddrs: []netip.Addr{network.Addr()},
 	}
-	h.buildNetworks(c.Certificate.Networks(), c.Certificate.UnsafeNetworks())
+	h.buildNetworks(myVpnNetworksTable, c.Certificate.Networks(), c.Certificate.UnsafeNetworks())
 
 	c1 := cert.CachedCertificate{
 		Certificate: &dummyCert{
@@ -493,7 +500,7 @@ func TestFirewall_Drop2(t *testing.T) {
 			peerCert: &c1,
 		},
 	}
-	h1.buildNetworks(c1.Certificate.Networks(), c1.Certificate.UnsafeNetworks())
+	h1.buildNetworks(myVpnNetworksTable, c1.Certificate.Networks(), c1.Certificate.UnsafeNetworks())
 
 	fw := NewFirewall(l, time.Second, time.Minute, time.Hour, c.Certificate)
 	require.NoError(t, fw.AddRule(true, firewall.ProtoAny, 0, 0, []string{"default-group", "test-group"}, "", netip.Prefix{}, netip.Prefix{}, "", ""))
@@ -510,6 +517,8 @@ func TestFirewall_Drop3(t *testing.T) {
 	l := test.NewLogger()
 	ob := &bytes.Buffer{}
 	l.SetOutput(ob)
+	myVpnNetworksTable := new(bart.Lite)
+	myVpnNetworksTable.Insert(netip.MustParsePrefix("1.1.1.1/8"))
 
 	p := firewall.Packet{
 		LocalAddr:  netip.MustParseAddr("1.2.3.4"),
@@ -541,7 +550,7 @@ func TestFirewall_Drop3(t *testing.T) {
 		},
 		vpnAddrs: []netip.Addr{network.Addr()},
 	}
-	h1.buildNetworks(c1.Certificate.Networks(), c1.Certificate.UnsafeNetworks())
+	h1.buildNetworks(myVpnNetworksTable, c1.Certificate.Networks(), c1.Certificate.UnsafeNetworks())
 
 	c2 := cert.CachedCertificate{
 		Certificate: &dummyCert{
@@ -556,7 +565,7 @@ func TestFirewall_Drop3(t *testing.T) {
 		},
 		vpnAddrs: []netip.Addr{network.Addr()},
 	}
-	h2.buildNetworks(c2.Certificate.Networks(), c2.Certificate.UnsafeNetworks())
+	h2.buildNetworks(myVpnNetworksTable, c2.Certificate.Networks(), c2.Certificate.UnsafeNetworks())
 
 	c3 := cert.CachedCertificate{
 		Certificate: &dummyCert{
@@ -571,7 +580,7 @@ func TestFirewall_Drop3(t *testing.T) {
 		},
 		vpnAddrs: []netip.Addr{network.Addr()},
 	}
-	h3.buildNetworks(c3.Certificate.Networks(), c3.Certificate.UnsafeNetworks())
+	h3.buildNetworks(myVpnNetworksTable, c3.Certificate.Networks(), c3.Certificate.UnsafeNetworks())
 
 	fw := NewFirewall(l, time.Second, time.Minute, time.Hour, c.Certificate)
 	require.NoError(t, fw.AddRule(true, firewall.ProtoAny, 1, 1, []string{}, "host1", netip.Prefix{}, netip.Prefix{}, "", ""))
@@ -597,6 +606,8 @@ func TestFirewall_Drop3V6(t *testing.T) {
 	l := test.NewLogger()
 	ob := &bytes.Buffer{}
 	l.SetOutput(ob)
+	myVpnNetworksTable := new(bart.Lite)
+	myVpnNetworksTable.Insert(netip.MustParsePrefix("fd00::/7"))
 
 	p := firewall.Packet{
 		LocalAddr:  netip.MustParseAddr("fd12::34"),
@@ -620,7 +631,7 @@ func TestFirewall_Drop3V6(t *testing.T) {
 		},
 		vpnAddrs: []netip.Addr{network.Addr()},
 	}
-	h.buildNetworks(c.Certificate.Networks(), c.Certificate.UnsafeNetworks())
+	h.buildNetworks(myVpnNetworksTable, c.Certificate.Networks(), c.Certificate.UnsafeNetworks())
 
 	// Test a remote address match
 	fw := NewFirewall(l, time.Second, time.Minute, time.Hour, c.Certificate)
@@ -633,6 +644,8 @@ func TestFirewall_DropConntrackReload(t *testing.T) {
 	l := test.NewLogger()
 	ob := &bytes.Buffer{}
 	l.SetOutput(ob)
+	myVpnNetworksTable := new(bart.Lite)
+	myVpnNetworksTable.Insert(netip.MustParsePrefix("1.1.1.1/8"))
 
 	p := firewall.Packet{
 		LocalAddr:  netip.MustParseAddr("1.2.3.4"),
@@ -659,7 +672,7 @@ func TestFirewall_DropConntrackReload(t *testing.T) {
 		},
 		vpnAddrs: []netip.Addr{network.Addr()},
 	}
-	h.buildNetworks(c.Certificate.Networks(), c.Certificate.UnsafeNetworks())
+	h.buildNetworks(myVpnNetworksTable, c.Certificate.Networks(), c.Certificate.UnsafeNetworks())
 
 	fw := NewFirewall(l, time.Second, time.Minute, time.Hour, c.Certificate)
 	require.NoError(t, fw.AddRule(true, firewall.ProtoAny, 0, 0, []string{"any"}, "", netip.Prefix{}, netip.Prefix{}, "", ""))
@@ -696,6 +709,8 @@ func TestFirewall_DropIPSpoofing(t *testing.T) {
 	l := test.NewLogger()
 	ob := &bytes.Buffer{}
 	l.SetOutput(ob)
+	myVpnNetworksTable := new(bart.Lite)
+	myVpnNetworksTable.Insert(netip.MustParsePrefix("192.0.2.1/24"))
 
 	c := cert.CachedCertificate{
 		Certificate: &dummyCert{
@@ -717,7 +732,7 @@ func TestFirewall_DropIPSpoofing(t *testing.T) {
 		},
 		vpnAddrs: []netip.Addr{c1.Certificate.Networks()[0].Addr()},
 	}
-	h1.buildNetworks(c1.Certificate.Networks(), c1.Certificate.UnsafeNetworks())
+	h1.buildNetworks(myVpnNetworksTable, c1.Certificate.Networks(), c1.Certificate.UnsafeNetworks())
 
 	fw := NewFirewall(l, time.Second, time.Minute, time.Hour, c.Certificate)
 

handshake_ix.go

@@ -183,17 +183,18 @@ func ixHandshakeStage1(f *Interface, addr netip.AddrPort, via *ViaSender, packet
 		return
 	}
 
-	var vpnAddrs []netip.Addr
-	var filteredNetworks []netip.Prefix
 	certName := remoteCert.Certificate.Name()
 	certVersion := remoteCert.Certificate.Version()
 	fingerprint := remoteCert.Fingerprint
 	issuer := remoteCert.Certificate.Issuer()
+	vpnNetworks := remoteCert.Certificate.Networks()
 
-	for _, network := range remoteCert.Certificate.Networks() {
+	anyVpnAddrsInCommon := false
+	vpnAddrs := make([]netip.Addr, len(vpnNetworks))
+	for i, network := range vpnNetworks {
 		vpnAddr := network.Addr()
 		if f.myVpnAddrsTable.Contains(vpnAddr) {
-			f.l.WithField("vpnAddr", vpnAddr).WithField("udpAddr", addr).
+			f.l.WithField("vpnNetworks", vpnNetworks).WithField("udpAddr", addr).
 				WithField("certName", certName).
 				WithField("certVersion", certVersion).
 				WithField("fingerprint", fingerprint).
@@ -201,24 +202,10 @@ func ixHandshakeStage1(f *Interface, addr netip.AddrPort, via *ViaSender, packet
 				WithField("handshake", m{"stage": 1, "style": "ix_psk0"}).Error("Refusing to handshake with myself")
 			return
 		}
-
+		vpnAddrs[i] = network.Addr()
-		// vpnAddrs outside our vpn networks are of no use to us, filter them out
+		if f.myVpnNetworksTable.Contains(vpnAddr) {
-		if !f.myVpnNetworksTable.Contains(vpnAddr) {
+			anyVpnAddrsInCommon = true
-			continue
 		}
-
-		filteredNetworks = append(filteredNetworks, network)
-		vpnAddrs = append(vpnAddrs, vpnAddr)
-	}
-
-	if len(vpnAddrs) == 0 {
-		f.l.WithError(err).WithField("udpAddr", addr).
-			WithField("certName", certName).
-			WithField("certVersion", certVersion).
-			WithField("fingerprint", fingerprint).
-			WithField("issuer", issuer).
-			WithField("handshake", m{"stage": 1, "style": "ix_psk0"}).Error("No usable vpn addresses from host, refusing handshake")
-		return
 	}
 
 	if addr.IsValid() {
@@ -255,26 +242,30 @@ func ixHandshakeStage1(f *Interface, addr netip.AddrPort, via *ViaSender, packet
 		},
 	}
 
-	f.l.WithField("vpnAddrs", vpnAddrs).WithField("udpAddr", addr).
+	msgRxL := f.l.WithFields(m{
-		WithField("certName", certName).
+		"vpnAddrs":       vpnAddrs,
-		WithField("certVersion", certVersion).
+		"udpAddr":        addr,
-		WithField("fingerprint", fingerprint).
+		"certName":       certName,
-		WithField("issuer", issuer).
+		"certVersion":    certVersion,
-		WithField("initiatorIndex", hs.Details.InitiatorIndex).WithField("responderIndex", hs.Details.ResponderIndex).
+		"fingerprint":    fingerprint,
-		WithField("remoteIndex", h.RemoteIndex).WithField("handshake", m{"stage": 1, "style": "ix_psk0"}).
+		"issuer":         issuer,
-		Info("Handshake message received")
+		"initiatorIndex": hs.Details.InitiatorIndex,
+		"responderIndex": hs.Details.ResponderIndex,
+		"remoteIndex":    h.RemoteIndex,
+		"handshake":      m{"stage": 1, "style": "ix_psk0"},
+	})
+
+	if anyVpnAddrsInCommon {
+		msgRxL.Info("Handshake message received")
+	} else {
+		//todo warn if not lighthouse or relay?
+		msgRxL.Info("Handshake message received, but no vpnNetworks in common.")
+	}
 
 	hs.Details.ResponderIndex = myIndex
 	hs.Details.Cert = cs.getHandshakeBytes(ci.myCert.Version())
 	if hs.Details.Cert == nil {
-		f.l.WithField("vpnAddrs", vpnAddrs).WithField("udpAddr", addr).
+		msgRxL.WithField("myCertVersion", ci.myCert.Version()).
-			WithField("certName", certName).
-			WithField("certVersion", certVersion).
-			WithField("fingerprint", fingerprint).
-			WithField("issuer", issuer).
-			WithField("initiatorIndex", hs.Details.InitiatorIndex).WithField("responderIndex", hs.Details.ResponderIndex).
-			WithField("remoteIndex", h.RemoteIndex).WithField("handshake", m{"stage": 1, "style": "ix_psk0"}).
-			WithField("certVersion", ci.myCert.Version()).
 			Error("Unable to handshake with host because no certificate handshake bytes is available")
 		return
 	}
@@ -332,7 +323,7 @@ func ixHandshakeStage1(f *Interface, addr netip.AddrPort, via *ViaSender, packet
 
 	hostinfo.remotes = f.lightHouse.QueryCache(vpnAddrs)
 	hostinfo.SetRemote(addr)
-	hostinfo.buildNetworks(filteredNetworks, remoteCert.Certificate.UnsafeNetworks())
+	hostinfo.buildNetworks(f.myVpnNetworksTable, remoteCert.Certificate.Networks(), remoteCert.Certificate.UnsafeNetworks())
 
 	existing, err := f.handshakeManager.CheckAndComplete(hostinfo, 0, f)
 	if err != nil {
@@ -573,30 +564,17 @@ func ixHandshakeStage2(f *Interface, addr netip.AddrPort, via *ViaSender, hh *Ha
 		hostinfo.relayState.InsertRelayTo(via.relayHI.vpnAddrs[0])
 	}
 
-	var vpnAddrs []netip.Addr
+	anyVpnAddrsInCommon := false
-	var filteredNetworks []netip.Prefix
+	vpnAddrs := make([]netip.Addr, len(vpnNetworks))
-	for _, network := range vpnNetworks {
+	for i, network := range vpnNetworks {
-		// vpnAddrs outside our vpn networks are of no use to us, filter them out
+		vpnAddrs[i] = network.Addr()
-		vpnAddr := network.Addr()
+		if f.myVpnNetworksTable.Contains(network.Addr()) {
-		if !f.myVpnNetworksTable.Contains(vpnAddr) {
+			anyVpnAddrsInCommon = true
-			continue
 		}
-
-		filteredNetworks = append(filteredNetworks, network)
-		vpnAddrs = append(vpnAddrs, vpnAddr)
-	}
-
-	if len(vpnAddrs) == 0 {
-		f.l.WithError(err).WithField("udpAddr", addr).
-			WithField("certName", certName).
-			WithField("certVersion", certVersion).
-			WithField("fingerprint", fingerprint).
-			WithField("issuer", issuer).
-			WithField("handshake", m{"stage": 2, "style": "ix_psk0"}).Error("No usable vpn addresses from host, refusing handshake")
-		return true
 	}
 
 	// Ensure the right host responded
+	// todo is it more correct to see if any of hostinfo.vpnAddrs are in the cert? it should have len==1, but one day it might not?
 	if !slices.Contains(vpnAddrs, hostinfo.vpnAddrs[0]) {
 		f.l.WithField("intendedVpnAddrs", hostinfo.vpnAddrs).WithField("haveVpnNetworks", vpnNetworks).
 			WithField("udpAddr", addr).
@@ -609,6 +587,7 @@ func ixHandshakeStage2(f *Interface, addr netip.AddrPort, via *ViaSender, hh *Ha
 		f.handshakeManager.DeleteHostInfo(hostinfo)
 
 		// Create a new hostinfo/handshake for the intended vpn ip
+		//TODO is hostinfo.vpnAddrs[0] always the address to use?
 		f.handshakeManager.StartHandshake(hostinfo.vpnAddrs[0], func(newHH *HandshakeHostInfo) {
 			// Block the current used address
 			newHH.hostinfo.remotes = hostinfo.remotes
@@ -635,7 +614,7 @@ func ixHandshakeStage2(f *Interface, addr netip.AddrPort, via *ViaSender, hh *Ha
 	ci.window.Update(f.l, 2)
 
 	duration := time.Since(hh.startTime).Nanoseconds()
-	f.l.WithField("vpnAddrs", vpnAddrs).WithField("udpAddr", addr).
+	msgRxL := f.l.WithField("vpnAddrs", vpnAddrs).WithField("udpAddr", addr).
 		WithField("certName", certName).
 		WithField("certVersion", certVersion).
 		WithField("fingerprint", fingerprint).
@@ -643,12 +622,17 @@ func ixHandshakeStage2(f *Interface, addr netip.AddrPort, via *ViaSender, hh *Ha
 		WithField("initiatorIndex", hs.Details.InitiatorIndex).WithField("responderIndex", hs.Details.ResponderIndex).
 		WithField("remoteIndex", h.RemoteIndex).WithField("handshake", m{"stage": 2, "style": "ix_psk0"}).
 		WithField("durationNs", duration).
-		WithField("sentCachedPackets", len(hh.packetStore)).
+		WithField("sentCachedPackets", len(hh.packetStore))
-		Info("Handshake message received")
+	if anyVpnAddrsInCommon {
+		msgRxL.Info("Handshake message received")
+	} else {
+		//todo warn if not lighthouse or relay?
+		msgRxL.Info("Handshake message received, but no vpnNetworks in common.")
+	}
 
 	// Build up the radix for the firewall if we have subnets in the cert
 	hostinfo.vpnAddrs = vpnAddrs
-	hostinfo.buildNetworks(filteredNetworks, remoteCert.Certificate.UnsafeNetworks())
+	hostinfo.buildNetworks(f.myVpnNetworksTable, remoteCert.Certificate.Networks(), remoteCert.Certificate.UnsafeNetworks())
 
 	// Complete our handshake and update metrics, this will replace any existing tunnels for the vpnAddrs here
 	f.handshakeManager.Complete(hostinfo, f)

hostmap.go

@@ -212,6 +212,18 @@ func (rs *RelayState) InsertRelay(ip netip.Addr, idx uint32, r *Relay) {
 	rs.relayForByIdx[idx] = r
 }
 
+type NetworkType uint8
+
+const (
+	NetworkTypeUnknown NetworkType = iota
+	// NetworkTypeVPN is a network that overlaps one or more of the vpnNetworks in our certificate
+	NetworkTypeVPN
+	// NetworkTypeVPNPeer is a network that does not overlap one of our networks
+	NetworkTypeVPNPeer
+	// NetworkTypeUnsafe is a network from Certificate.UnsafeNetworks()
+	NetworkTypeUnsafe
+)
+
 type HostInfo struct {
 	remote          netip.AddrPort
 	remotes         *RemoteList
@@ -220,13 +232,11 @@ type HostInfo struct {
 	remoteIndexId   uint32
 	localIndexId    uint32
 
-	// vpnAddrs is a list of vpn addresses assigned to this host that are within our own vpn networks
+	// vpnAddrs is a list of vpn addresses assigned to this host
-	// The host may have other vpn addresses that are outside our
-	// vpn networks but were removed because they are not usable
 	vpnAddrs []netip.Addr
 
-	// networks are both all vpn and unsafe networks assigned to this host
+	// networks is a combination of specific vpn addresses (not prefixes!) and full unsafe networks assigned to this host.
-	networks   *bart.Lite
+	networks   *bart.Table[NetworkType]
 	relayState RelayState
 
 	// HandshakePacket records the packets used to create this hostinfo
@@ -730,20 +740,27 @@ func (i *HostInfo) SetRemoteIfPreferred(hm *HostMap, newRemote netip.AddrPort) b
 	return false
 }
 
-func (i *HostInfo) buildNetworks(networks, unsafeNetworks []netip.Prefix) {
+func (i *HostInfo) buildNetworks(myVpnNetworksTable *bart.Lite, networks, unsafeNetworks []netip.Prefix) {
 	if len(networks) == 1 && len(unsafeNetworks) == 0 {
-		// Simple case, no CIDRTree needed
+		if myVpnNetworksTable.Contains(networks[0].Addr()) {
-		return
+			return // Simple case, no CIDRTree needed
+		}
 	}
 
-	i.networks = new(bart.Lite)
+	i.networks = new(bart.Table[NetworkType])
 	for _, network := range networks {
+		var nwType NetworkType
+		if myVpnNetworksTable.Contains(network.Addr()) {
+			nwType = NetworkTypeVPN
+		} else {
+			nwType = NetworkTypeVPNPeer
+		}
 		nprefix := netip.PrefixFrom(network.Addr(), network.Addr().BitLen())
-		i.networks.Insert(nprefix)
+		i.networks.Insert(nprefix, nwType)
 	}
 
 	for _, network := range unsafeNetworks {
-		i.networks.Insert(network)
+		i.networks.Insert(network, NetworkTypeUnsafe)
 	}
 }
 

lighthouse.go

@@ -1017,17 +1017,17 @@ func (lhh *LightHouseHandler) resetMeta() *NebulaMeta {
 	return lhh.meta
 }
 
-func (lhh *LightHouseHandler) HandleRequest(rAddr netip.AddrPort, fromVpnAddrs []netip.Addr, p []byte, w EncWriter) {
+func (lhh *LightHouseHandler) HandleRequest(rAddr netip.AddrPort, hostinfo *HostInfo, p []byte, w EncWriter) {
 	n := lhh.resetMeta()
 	err := n.Unmarshal(p)
 	if err != nil {
-		lhh.l.WithError(err).WithField("vpnAddrs", fromVpnAddrs).WithField("udpAddr", rAddr).
+		lhh.l.WithError(err).WithField("vpnAddrs", hostinfo.vpnAddrs).WithField("udpAddr", rAddr).
 			Error("Failed to unmarshal lighthouse packet")
 		return
 	}
 
 	if n.Details == nil {
-		lhh.l.WithField("vpnAddrs", fromVpnAddrs).WithField("udpAddr", rAddr).
+		lhh.l.WithField("vpnAddrs", hostinfo.vpnAddrs).WithField("udpAddr", rAddr).
 			Error("Invalid lighthouse update")
 		return
 	}
@@ -1036,24 +1036,24 @@ func (lhh *LightHouseHandler) HandleRequest(rAddr netip.AddrPort, fromVpnAddrs [
 
 	switch n.Type {
 	case NebulaMeta_HostQuery:
-		lhh.handleHostQuery(n, fromVpnAddrs, rAddr, w)
+		lhh.handleHostQuery(n, hostinfo, rAddr, w)
 
 	case NebulaMeta_HostQueryReply:
-		lhh.handleHostQueryReply(n, fromVpnAddrs)
+		lhh.handleHostQueryReply(n, hostinfo.vpnAddrs)
 
 	case NebulaMeta_HostUpdateNotification:
-		lhh.handleHostUpdateNotification(n, fromVpnAddrs, w)
+		lhh.handleHostUpdateNotification(n, hostinfo, w)
 
 	case NebulaMeta_HostMovedNotification:
 	case NebulaMeta_HostPunchNotification:
-		lhh.handleHostPunchNotification(n, fromVpnAddrs, w)
+		lhh.handleHostPunchNotification(n, hostinfo.vpnAddrs, w)
 
 	case NebulaMeta_HostUpdateNotificationAck:
 		// noop
 	}
 }
 
-func (lhh *LightHouseHandler) handleHostQuery(n *NebulaMeta, fromVpnAddrs []netip.Addr, addr netip.AddrPort, w EncWriter) {
+func (lhh *LightHouseHandler) handleHostQuery(n *NebulaMeta, hostinfo *HostInfo, addr netip.AddrPort, w EncWriter) {
 	// Exit if we don't answer queries
 	if !lhh.lh.amLighthouse {
 		if lhh.l.Level >= logrus.DebugLevel {
@@ -1065,7 +1065,7 @@ func (lhh *LightHouseHandler) handleHostQuery(n *NebulaMeta, fromVpnAddrs []neti
 	queryVpnAddr, useVersion, err := n.Details.GetVpnAddrAndVersion()
 	if err != nil {
 		if lhh.l.Level >= logrus.DebugLevel {
-			lhh.l.WithField("from", fromVpnAddrs).WithField("details", n.Details).
+			lhh.l.WithField("from", hostinfo.vpnAddrs).WithField("details", n.Details).
 				Debugln("Dropping malformed HostQuery")
 		}
 		return
@@ -1073,7 +1073,7 @@ func (lhh *LightHouseHandler) handleHostQuery(n *NebulaMeta, fromVpnAddrs []neti
 	if useVersion == cert.Version1 && queryVpnAddr.Is6() {
 		// this case really shouldn't be possible to represent, but reject it anyway.
 		if lhh.l.Level >= logrus.DebugLevel {
-			lhh.l.WithField("vpnAddrs", fromVpnAddrs).WithField("queryVpnAddr", queryVpnAddr).
+			lhh.l.WithField("vpnAddrs", hostinfo.vpnAddrs).WithField("queryVpnAddr", queryVpnAddr).
 				Debugln("invalid vpn addr for v1 handleHostQuery")
 		}
 		return
@@ -1099,14 +1099,14 @@ func (lhh *LightHouseHandler) handleHostQuery(n *NebulaMeta, fromVpnAddrs []neti
 	}
 
 	if err != nil {
-		lhh.l.WithError(err).WithField("vpnAddrs", fromVpnAddrs).Error("Failed to marshal lighthouse host query reply")
+		lhh.l.WithError(err).WithField("vpnAddrs", hostinfo.vpnAddrs).Error("Failed to marshal lighthouse host query reply")
 		return
 	}
 
 	lhh.lh.metricTx(NebulaMeta_HostQueryReply, 1)
-	w.SendMessageToVpnAddr(header.LightHouse, 0, fromVpnAddrs[0], lhh.pb[:ln], lhh.nb, lhh.out[:0])
+	w.SendMessageToHostInfo(header.LightHouse, 0, hostinfo, lhh.pb[:ln], lhh.nb, lhh.out[:0])
 
-	lhh.sendHostPunchNotification(n, fromVpnAddrs, queryVpnAddr, w)
+	lhh.sendHostPunchNotification(n, hostinfo.vpnAddrs, queryVpnAddr, w)
 }
 
 // sendHostPunchNotification signals the other side to punch some zero byte udp packets
@@ -1115,20 +1115,34 @@ func (lhh *LightHouseHandler) sendHostPunchNotification(n *NebulaMeta, fromVpnAd
 	found, ln, err := lhh.lh.queryAndPrepMessage(whereToPunch, func(c *cache) (int, error) {
 		n = lhh.resetMeta()
 		n.Type = NebulaMeta_HostPunchNotification
-		targetHI := lhh.lh.ifce.GetHostInfo(punchNotifDest)
+		punchNotifDestHI := lhh.lh.ifce.GetHostInfo(punchNotifDest)
 		var useVersion cert.Version
-		if targetHI == nil {
+		if punchNotifDestHI == nil {
 			useVersion = lhh.lh.ifce.GetCertState().initiatingVersion
 		} else {
-			crt := targetHI.GetCert().Certificate
-			useVersion = crt.Version()
 			// we can only retarget if we have a hostinfo
-			newDest, ok := findNetworkUnion(crt.Networks(), fromVpnAddrs)
+			punchNotifDestCrt := punchNotifDestHI.GetCert().Certificate
+			useVersion = punchNotifDestCrt.Version()
+			punchNotifDestNetworks := punchNotifDestCrt.Networks()
+
+			//if we (the lighthouse) don't have a network in common with punchNotifDest, try to find one
+			if !lhh.lh.myVpnNetworksTable.Contains(punchNotifDest) {
+				newPunchNotifDest, ok := findNetworkUnion(lhh.lh.myVpnNetworks, punchNotifDestHI.vpnAddrs)
+				if ok {
+					punchNotifDest = newPunchNotifDest
+				} else {
+					if lhh.l.Level >= logrus.DebugLevel {
+						lhh.l.WithField("to", punchNotifDestNetworks).Debugln("unable to notify host to host, no addresses in common")
+					}
+				}
+			}
+
+			newWhereToPunch, ok := findNetworkUnion(punchNotifDestNetworks, fromVpnAddrs)
 			if ok {
-				whereToPunch = newDest
+				whereToPunch = newWhereToPunch
 			} else {
 				if lhh.l.Level >= logrus.DebugLevel {
-					lhh.l.WithField("to", crt.Networks()).Debugln("unable to punch to host, no addresses in common")
+					lhh.l.WithFields(m{"from": fromVpnAddrs, "to": punchNotifDestNetworks}).Debugln("unable to punch to host, no addresses in common with requestor")
 				}
 			}
 		}
@@ -1234,7 +1248,8 @@ func (lhh *LightHouseHandler) handleHostQueryReply(n *NebulaMeta, fromVpnAddrs [
 	}
 }
 
-func (lhh *LightHouseHandler) handleHostUpdateNotification(n *NebulaMeta, fromVpnAddrs []netip.Addr, w EncWriter) {
+func (lhh *LightHouseHandler) handleHostUpdateNotification(n *NebulaMeta, hostinfo *HostInfo, w EncWriter) {
+	fromVpnAddrs := hostinfo.vpnAddrs
 	if !lhh.lh.amLighthouse {
 		if lhh.l.Level >= logrus.DebugLevel {
 			lhh.l.Debugln("I am not a lighthouse, do not take host updates: ", fromVpnAddrs)
@@ -1302,7 +1317,7 @@ func (lhh *LightHouseHandler) handleHostUpdateNotification(n *NebulaMeta, fromVp
 	}
 
 	lhh.lh.metricTx(NebulaMeta_HostUpdateNotificationAck, 1)
-	w.SendMessageToVpnAddr(header.LightHouse, 0, fromVpnAddrs[0], lhh.pb[:ln], lhh.nb, lhh.out[:0])
+	w.SendMessageToHostInfo(header.LightHouse, 0, hostinfo, lhh.pb[:ln], lhh.nb, lhh.out[:0])
 }
 
 func (lhh *LightHouseHandler) handleHostPunchNotification(n *NebulaMeta, fromVpnAddrs []netip.Addr, w EncWriter) {

lighthouse_test.go

@@ -132,8 +132,13 @@ func BenchmarkLighthouseHandleRequest(b *testing.B) {
 	)
 
 	mw := &mockEncWriter{}
-
+	hostinfo := &HostInfo{
-	hi := []netip.Addr{vpnIp2}
+		ConnectionState: &ConnectionState{
+			eKey: nil,
+			dKey: nil,
+		},
+		vpnAddrs: []netip.Addr{vpnIp2},
+	}
 	b.Run("notfound", func(b *testing.B) {
 		lhh := lh.NewRequestHandler()
 		req := &NebulaMeta{
@@ -146,7 +151,7 @@ func BenchmarkLighthouseHandleRequest(b *testing.B) {
 		p, err := req.Marshal()
 		require.NoError(b, err)
 		for n := 0; n < b.N; n++ {
-			lhh.HandleRequest(rAddr, hi, p, mw)
+			lhh.HandleRequest(rAddr, hostinfo, p, mw)
 		}
 	})
 	b.Run("found", func(b *testing.B) {
@@ -162,7 +167,7 @@ func BenchmarkLighthouseHandleRequest(b *testing.B) {
 		require.NoError(b, err)
 
 		for n := 0; n < b.N; n++ {
-			lhh.HandleRequest(rAddr, hi, p, mw)
+			lhh.HandleRequest(rAddr, hostinfo, p, mw)
 		}
 	})
 }
@@ -326,7 +331,14 @@ func newLHHostRequest(fromAddr netip.AddrPort, myVpnIp, queryVpnIp netip.Addr, l
 	w := &testEncWriter{
 		metaFilter: &filter,
 	}
-	lhh.HandleRequest(fromAddr, []netip.Addr{myVpnIp}, b, w)
+	hostinfo := &HostInfo{
+		ConnectionState: &ConnectionState{
+			eKey: nil,
+			dKey: nil,
+		},
+		vpnAddrs: []netip.Addr{myVpnIp},
+	}
+	lhh.HandleRequest(fromAddr, hostinfo, b, w)
 	return w.lastReply
 }
 
@@ -355,9 +367,15 @@ func newLHHostUpdate(fromAddr netip.AddrPort, vpnIp netip.Addr, addrs []netip.Ad
 	if err != nil {
 		panic(err)
 	}
-
+	hostinfo := &HostInfo{
+		ConnectionState: &ConnectionState{
+			eKey: nil,
+			dKey: nil,
+		},
+		vpnAddrs: []netip.Addr{vpnIp},
+	}
 	w := &testEncWriter{}
-	lhh.HandleRequest(fromAddr, []netip.Addr{vpnIp}, b, w)
+	lhh.HandleRequest(fromAddr, hostinfo, b, w)
 }
 
 type testLhReply struct {

outside.go

@@ -138,7 +138,7 @@ func (f *Interface) readOutsidePackets(ip netip.AddrPort, via *ViaSender, out []
 			return
 		}
 
-		lhf.HandleRequest(ip, hostinfo.vpnAddrs, d, f)
+		lhf.HandleRequest(ip, hostinfo, d, f)
 
 		// Fallthrough to the bottom to record incoming traffic