V2 certificate format (#1216)

Co-authored-by: Nate Brown <nbrown.us@gmail.com> Co-authored-by: Jack Doan <jackdoan@rivian.com> Co-authored-by: brad-defined <77982333+brad-defined@users.noreply.github.com> Co-authored-by: Jack Doan <me@jackdoan.com>
2025-11-22 08:24:25 +01:00 · 2025-03-06 11:28:26 -06:00
parent 2b427a7e89
commit d97ed57a19
105 changed files with 8276 additions and 4528 deletions
--- a/handshake_ix.go
+++ b/handshake_ix.go
@@ -2,10 +2,12 @@ package nebula

 import (
 	"net/netip"
+	"slices"
 	"time"

 	"github.com/flynn/noise"
 	"github.com/sirupsen/logrus"
+	"github.com/slackhq/nebula/cert"
 	"github.com/slackhq/nebula/header"
 )

@@ -16,30 +18,60 @@ import (
 func ixHandshakeStage0(f *Interface, hh *HandshakeHostInfo) bool {
 	err := f.handshakeManager.allocateIndex(hh)
 	if err != nil {
-		f.l.WithError(err).WithField("vpnIp", hh.hostinfo.vpnIp).
+		f.l.WithError(err).WithField("vpnAddrs", hh.hostinfo.vpnAddrs).
 			WithField("handshake", m{"stage": 0, "style": "ix_psk0"}).Error("Failed to generate index")
 		return false
 	}

-	certState := f.pki.GetCertState()
-	ci := NewConnectionState(f.l, f.cipher, certState, true, noise.HandshakeIX, []byte{}, 0)
+	// If we're connecting to a v6 address we must use a v2 cert
+	cs := f.pki.getCertState()
+	v := cs.defaultVersion
+	for _, a := range hh.hostinfo.vpnAddrs {
+		if a.Is6() {
+			v = cert.Version2
+			break
+		}
+	}
+
+	crt := cs.getCertificate(v)
+	if crt == nil {
+		f.l.WithField("vpnAddrs", hh.hostinfo.vpnAddrs).
+			WithField("handshake", m{"stage": 0, "style": "ix_psk0"}).
+			WithField("certVersion", v).
+			Error("Unable to handshake with host because no certificate is available")
+		return false
+	}
+
+	crtHs := cs.getHandshakeBytes(v)
+	if crtHs == nil {
+		f.l.WithField("vpnAddrs", hh.hostinfo.vpnAddrs).
+			WithField("handshake", m{"stage": 0, "style": "ix_psk0"}).
+			WithField("certVersion", v).
+			Error("Unable to handshake with host because no certificate handshake bytes is available")
+	}
+
+	ci, err := NewConnectionState(f.l, cs, crt, true, noise.HandshakeIX)
+	if err != nil {
+		f.l.WithError(err).WithField("vpnAddrs", hh.hostinfo.vpnAddrs).
+			WithField("handshake", m{"stage": 0, "style": "ix_psk0"}).
+			WithField("certVersion", v).
+			Error("Failed to create connection state")
+		return false
+	}
 	hh.hostinfo.ConnectionState = ci

-	hsProto := &NebulaHandshakeDetails{
-		InitiatorIndex: hh.hostinfo.localIndexId,
-		Time:           uint64(time.Now().UnixNano()),
-		Cert:           certState.RawCertificateNoKey,
-	}
-
-	hsBytes := []byte{}
-
 	hs := &NebulaHandshake{
-		Details: hsProto,
+		Details: &NebulaHandshakeDetails{
+			InitiatorIndex: hh.hostinfo.localIndexId,
+			Time:           uint64(time.Now().UnixNano()),
+			Cert:           crtHs,
+			CertVersion:    uint32(v),
+		},
 	}
-	hsBytes, err = hs.Marshal()

+	hsBytes, err := hs.Marshal()
 	if err != nil {
-		f.l.WithError(err).WithField("vpnIp", hh.hostinfo.vpnIp).
+		f.l.WithError(err).WithField("vpnAddrs", hh.hostinfo.vpnAddrs).WithField("certVersion", v).
 			WithField("handshake", m{"stage": 0, "style": "ix_psk0"}).Error("Failed to marshal handshake message")
 		return false
 	}
@@ -48,7 +80,7 @@ func ixHandshakeStage0(f *Interface, hh *HandshakeHostInfo) bool {

 	msg, _, _, err := ci.H.WriteMessage(h, hsBytes)
 	if err != nil {
-		f.l.WithError(err).WithField("vpnIp", hh.hostinfo.vpnIp).
+		f.l.WithError(err).WithField("vpnAddrs", hh.hostinfo.vpnAddrs).
 			WithField("handshake", m{"stage": 0, "style": "ix_psk0"}).Error("Failed to call noise.WriteMessage")
 		return false
 	}
@@ -63,30 +95,44 @@ func ixHandshakeStage0(f *Interface, hh *HandshakeHostInfo) bool {
 }

 func ixHandshakeStage1(f *Interface, addr netip.AddrPort, via *ViaSender, packet []byte, h *header.H) {
-	certState := f.pki.GetCertState()
-	ci := NewConnectionState(f.l, f.cipher, certState, false, noise.HandshakeIX, []byte{}, 0)
+	cs := f.pki.getCertState()
+	crt := cs.GetDefaultCertificate()
+	if crt == nil {
+		f.l.WithField("udpAddr", addr).
+			WithField("handshake", m{"stage": 0, "style": "ix_psk0"}).
+			WithField("certVersion", cs.defaultVersion).
+			Error("Unable to handshake with host because no certificate is available")
+	}
+
+	ci, err := NewConnectionState(f.l, cs, crt, false, noise.HandshakeIX)
+	if err != nil {
+		f.l.WithError(err).WithField("udpAddr", addr).
+			WithField("handshake", m{"stage": 1, "style": "ix_psk0"}).
+			Error("Failed to create connection state")
+		return
+	}
+
 	// Mark packet 1 as seen so it doesn't show up as missed
 	ci.window.Update(f.l, 1)

 	msg, _, _, err := ci.H.ReadMessage(nil, packet[header.Len:])
 	if err != nil {
 		f.l.WithError(err).WithField("udpAddr", addr).
-			WithField("handshake", m{"stage": 1, "style": "ix_psk0"}).Error("Failed to call noise.ReadMessage")
+			WithField("handshake", m{"stage": 1, "style": "ix_psk0"}).
+			Error("Failed to call noise.ReadMessage")
 		return
 	}

 	hs := &NebulaHandshake{}
 	err = hs.Unmarshal(msg)
-	/*
-		l.Debugln("GOT INDEX: ", hs.Details.InitiatorIndex)
-	*/
 	if err != nil || hs.Details == nil {
 		f.l.WithError(err).WithField("udpAddr", addr).
-			WithField("handshake", m{"stage": 1, "style": "ix_psk0"}).Error("Failed unmarshal handshake message")
+			WithField("handshake", m{"stage": 1, "style": "ix_psk0"}).
+			Error("Failed unmarshal handshake message")
 		return
 	}

-	remoteCert, err := RecombineCertAndValidate(ci.H, hs.Details.Cert, f.pki.GetCAPool())
+	remoteCert, err := cert.RecombineAndValidate(cert.Version(hs.Details.CertVersion), hs.Details.Cert, ci.H.PeerStatic(), ci.Curve(), f.pki.GetCAPool())
 	if err != nil {
 		e := f.l.WithError(err).WithField("udpAddr", addr).
 			WithField("handshake", m{"stage": 1, "style": "ix_psk0"})
@@ -99,6 +145,20 @@ func ixHandshakeStage1(f *Interface, addr netip.AddrPort, via *ViaSender, packet
 		return
 	}

+	if remoteCert.Certificate.Version() != ci.myCert.Version() {
+		// We started off using the wrong certificate version, lets see if we can match the version that was sent to us
+		rc := cs.getCertificate(remoteCert.Certificate.Version())
+		if rc == nil {
+			f.l.WithError(err).WithField("udpAddr", addr).
+				WithField("handshake", m{"stage": 1, "style": "ix_psk0"}).WithField("cert", remoteCert).
+				Info("Unable to handshake with host due to missing certificate version")
+			return
+		}
+
+		// Record the certificate we are actually using
+		ci.myCert = rc
+	}
+
 	if len(remoteCert.Certificate.Networks()) == 0 {
 		e := f.l.WithError(err).WithField("udpAddr", addr).
 			WithField("handshake", m{"stage": 1, "style": "ix_psk0"})
@@ -111,30 +171,54 @@ func ixHandshakeStage1(f *Interface, addr netip.AddrPort, via *ViaSender, packet
 		return
 	}

-	vpnIp := remoteCert.Certificate.Networks()[0].Addr().Unmap()
+	var vpnAddrs []netip.Addr
+	var filteredNetworks []netip.Prefix
 	certName := remoteCert.Certificate.Name()
 	fingerprint := remoteCert.Fingerprint
 	issuer := remoteCert.Certificate.Issuer()

-	if vpnIp == f.myVpnNet.Addr() {
-		f.l.WithField("vpnIp", vpnIp).WithField("udpAddr", addr).
+	for _, network := range remoteCert.Certificate.Networks() {
+		vpnAddr := network.Addr()
+		_, found := f.myVpnAddrsTable.Lookup(vpnAddr)
+		if found {
+			f.l.WithField("vpnAddr", vpnAddr).WithField("udpAddr", addr).
+				WithField("certName", certName).
+				WithField("fingerprint", fingerprint).
+				WithField("issuer", issuer).
+				WithField("handshake", m{"stage": 1, "style": "ix_psk0"}).Error("Refusing to handshake with myself")
+			return
+		}
+
+		// vpnAddrs outside our vpn networks are of no use to us, filter them out
+		if _, ok := f.myVpnNetworksTable.Lookup(vpnAddr); !ok {
+			continue
+		}
+
+		filteredNetworks = append(filteredNetworks, network)
+		vpnAddrs = append(vpnAddrs, vpnAddr)
+	}
+
+	if len(vpnAddrs) == 0 {
+		f.l.WithError(err).WithField("udpAddr", addr).
 			WithField("certName", certName).
 			WithField("fingerprint", fingerprint).
 			WithField("issuer", issuer).
-			WithField("handshake", m{"stage": 1, "style": "ix_psk0"}).Error("Refusing to handshake with myself")
+			WithField("handshake", m{"stage": 1, "style": "ix_psk0"}).Error("No usable vpn addresses from host, refusing handshake")
 		return
 	}

 	if addr.IsValid() {
-		if !f.lightHouse.GetRemoteAllowList().Allow(vpnIp, addr.Addr()) {
-			f.l.WithField("vpnIp", vpnIp).WithField("udpAddr", addr).Debug("lighthouse.remote_allow_list denied incoming handshake")
+		// addr can be invalid when the tunnel is being relayed.
+		// We only want to apply the remote allow list for direct tunnels here
+		if !f.lightHouse.GetRemoteAllowList().AllowAll(vpnAddrs, addr.Addr()) {
+			f.l.WithField("vpnAddrs", vpnAddrs).WithField("udpAddr", addr).Debug("lighthouse.remote_allow_list denied incoming handshake")
 			return
 		}
 	}

 	myIndex, err := generateIndex(f.l)
 	if err != nil {
-		f.l.WithError(err).WithField("vpnIp", vpnIp).WithField("udpAddr", addr).
+		f.l.WithError(err).WithField("vpnAddrs", vpnAddrs).WithField("udpAddr", addr).
 			WithField("certName", certName).
 			WithField("fingerprint", fingerprint).
 			WithField("issuer", issuer).
@@ -146,17 +230,17 @@ func ixHandshakeStage1(f *Interface, addr netip.AddrPort, via *ViaSender, packet
 		ConnectionState:   ci,
 		localIndexId:      myIndex,
 		remoteIndexId:     hs.Details.InitiatorIndex,
-		vpnIp:             vpnIp,
+		vpnAddrs:          vpnAddrs,
 		HandshakePacket:   make(map[uint8][]byte, 0),
 		lastHandshakeTime: hs.Details.Time,
 		relayState: RelayState{
-			relays:        map[netip.Addr]struct{}{},
-			relayForByIp:  map[netip.Addr]*Relay{},
-			relayForByIdx: map[uint32]*Relay{},
+			relays:         map[netip.Addr]struct{}{},
+			relayForByAddr: map[netip.Addr]*Relay{},
+			relayForByIdx:  map[uint32]*Relay{},
 		},
 	}

-	f.l.WithField("vpnIp", vpnIp).WithField("udpAddr", addr).
+	f.l.WithField("vpnAddrs", vpnAddrs).WithField("udpAddr", addr).
 		WithField("certName", certName).
 		WithField("fingerprint", fingerprint).
 		WithField("issuer", issuer).
@@ -165,13 +249,26 @@ func ixHandshakeStage1(f *Interface, addr netip.AddrPort, via *ViaSender, packet
 		Info("Handshake message received")

 	hs.Details.ResponderIndex = myIndex
-	hs.Details.Cert = certState.RawCertificateNoKey
+	hs.Details.Cert = cs.getHandshakeBytes(ci.myCert.Version())
+	if hs.Details.Cert == nil {
+		f.l.WithField("vpnAddrs", vpnAddrs).WithField("udpAddr", addr).
+			WithField("certName", certName).
+			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
+	}
+
+	hs.Details.CertVersion = uint32(ci.myCert.Version())
 	// Update the time in case their clock is way off from ours
 	hs.Details.Time = uint64(time.Now().UnixNano())

 	hsBytes, err := hs.Marshal()
 	if err != nil {
-		f.l.WithError(err).WithField("vpnIp", hostinfo.vpnIp).WithField("udpAddr", addr).
+		f.l.WithError(err).WithField("vpnAddrs", hostinfo.vpnAddrs).WithField("udpAddr", addr).
 			WithField("certName", certName).
 			WithField("fingerprint", fingerprint).
 			WithField("issuer", issuer).
@@ -182,14 +279,14 @@ func ixHandshakeStage1(f *Interface, addr netip.AddrPort, via *ViaSender, packet
 	nh := header.Encode(make([]byte, header.Len), header.Version, header.Handshake, header.HandshakeIXPSK0, hs.Details.InitiatorIndex, 2)
 	msg, dKey, eKey, err := ci.H.WriteMessage(nh, hsBytes)
 	if err != nil {
-		f.l.WithError(err).WithField("vpnIp", hostinfo.vpnIp).WithField("udpAddr", addr).
+		f.l.WithError(err).WithField("vpnAddrs", hostinfo.vpnAddrs).WithField("udpAddr", addr).
 			WithField("certName", certName).
 			WithField("fingerprint", fingerprint).
 			WithField("issuer", issuer).
 			WithField("handshake", m{"stage": 1, "style": "ix_psk0"}).Error("Failed to call noise.WriteMessage")
 		return
 	} else if dKey == nil || eKey == nil {
-		f.l.WithField("vpnIp", hostinfo.vpnIp).WithField("udpAddr", addr).
+		f.l.WithField("vpnAddrs", hostinfo.vpnAddrs).WithField("udpAddr", addr).
 			WithField("certName", certName).
 			WithField("fingerprint", fingerprint).
 			WithField("issuer", issuer).
@@ -213,9 +310,9 @@ func ixHandshakeStage1(f *Interface, addr netip.AddrPort, via *ViaSender, packet
 	ci.dKey = NewNebulaCipherState(dKey)
 	ci.eKey = NewNebulaCipherState(eKey)

-	hostinfo.remotes = f.lightHouse.QueryCache(vpnIp)
+	hostinfo.remotes = f.lightHouse.QueryCache(vpnAddrs)
 	hostinfo.SetRemote(addr)
-	hostinfo.CreateRemoteCIDR(remoteCert.Certificate)
+	hostinfo.buildNetworks(filteredNetworks, remoteCert.Certificate.UnsafeNetworks())

 	existing, err := f.handshakeManager.CheckAndComplete(hostinfo, 0, f)
 	if err != nil {
@@ -225,7 +322,7 @@ func ixHandshakeStage1(f *Interface, addr netip.AddrPort, via *ViaSender, packet
 			if existing.SetRemoteIfPreferred(f.hostMap, addr) {
 				// Send a test packet to ensure the other side has also switched to
 				// the preferred remote
-				f.SendMessageToVpnIp(header.Test, header.TestRequest, vpnIp, []byte(""), make([]byte, 12, 12), make([]byte, mtu))
+				f.SendMessageToVpnAddr(header.Test, header.TestRequest, vpnAddrs[0], []byte(""), make([]byte, 12, 12), make([]byte, mtu))
 			}

 			msg = existing.HandshakePacket[2]
@@ -233,11 +330,11 @@ func ixHandshakeStage1(f *Interface, addr netip.AddrPort, via *ViaSender, packet
 			if addr.IsValid() {
 				err := f.outside.WriteTo(msg, addr)
 				if err != nil {
-					f.l.WithField("vpnIp", existing.vpnIp).WithField("udpAddr", addr).
+					f.l.WithField("vpnAddrs", existing.vpnAddrs).WithField("udpAddr", addr).
 						WithField("handshake", m{"stage": 2, "style": "ix_psk0"}).WithField("cached", true).
 						WithError(err).Error("Failed to send handshake message")
 				} else {
-					f.l.WithField("vpnIp", existing.vpnIp).WithField("udpAddr", addr).
+					f.l.WithField("vpnAddrs", existing.vpnAddrs).WithField("udpAddr", addr).
 						WithField("handshake", m{"stage": 2, "style": "ix_psk0"}).WithField("cached", true).
 						Info("Handshake message sent")
 				}
@@ -247,16 +344,16 @@ func ixHandshakeStage1(f *Interface, addr netip.AddrPort, via *ViaSender, packet
 					f.l.Error("Handshake send failed: both addr and via are nil.")
 					return
 				}
-				hostinfo.relayState.InsertRelayTo(via.relayHI.vpnIp)
+				hostinfo.relayState.InsertRelayTo(via.relayHI.vpnAddrs[0])
 				f.SendVia(via.relayHI, via.relay, msg, make([]byte, 12), make([]byte, mtu), false)
-				f.l.WithField("vpnIp", existing.vpnIp).WithField("relay", via.relayHI.vpnIp).
+				f.l.WithField("vpnAddrs", existing.vpnAddrs).WithField("relay", via.relayHI.vpnAddrs[0]).
 					WithField("handshake", m{"stage": 2, "style": "ix_psk0"}).WithField("cached", true).
 					Info("Handshake message sent")
 				return
 			}
 		case ErrExistingHostInfo:
 			// This means there was an existing tunnel and this handshake was older than the one we are currently based on
-			f.l.WithField("vpnIp", vpnIp).WithField("udpAddr", addr).
+			f.l.WithField("vpnAddrs", vpnAddrs).WithField("udpAddr", addr).
 				WithField("certName", certName).
 				WithField("oldHandshakeTime", existing.lastHandshakeTime).
 				WithField("newHandshakeTime", hostinfo.lastHandshakeTime).
@@ -267,23 +364,23 @@ func ixHandshakeStage1(f *Interface, addr netip.AddrPort, via *ViaSender, packet
 				Info("Handshake too old")

 			// Send a test packet to trigger an authenticated tunnel test, this should suss out any lingering tunnel issues
-			f.SendMessageToVpnIp(header.Test, header.TestRequest, vpnIp, []byte(""), make([]byte, 12, 12), make([]byte, mtu))
+			f.SendMessageToVpnAddr(header.Test, header.TestRequest, vpnAddrs[0], []byte(""), make([]byte, 12, 12), make([]byte, mtu))
 			return
 		case ErrLocalIndexCollision:
 			// This means we failed to insert because of collision on localIndexId. Just let the next handshake packet retry
-			f.l.WithField("vpnIp", vpnIp).WithField("udpAddr", addr).
+			f.l.WithField("vpnAddrs", vpnAddrs).WithField("udpAddr", addr).
 				WithField("certName", certName).
 				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("localIndex", hostinfo.localIndexId).WithField("collision", existing.vpnIp).
+				WithField("localIndex", hostinfo.localIndexId).WithField("collision", existing.vpnAddrs).
 				Error("Failed to add HostInfo due to localIndex collision")
 			return
 		default:
 			// Shouldn't happen, but just in case someone adds a new error type to CheckAndComplete
 			// And we forget to update it here
-			f.l.WithError(err).WithField("vpnIp", vpnIp).WithField("udpAddr", addr).
+			f.l.WithError(err).WithField("vpnAddrs", vpnAddrs).WithField("udpAddr", addr).
 				WithField("certName", certName).
 				WithField("fingerprint", fingerprint).
 				WithField("issuer", issuer).
@@ -299,7 +396,7 @@ func ixHandshakeStage1(f *Interface, addr netip.AddrPort, via *ViaSender, packet
 	if addr.IsValid() {
 		err = f.outside.WriteTo(msg, addr)
 		if err != nil {
-			f.l.WithField("vpnIp", vpnIp).WithField("udpAddr", addr).
+			f.l.WithField("vpnAddrs", vpnAddrs).WithField("udpAddr", addr).
 				WithField("certName", certName).
 				WithField("fingerprint", fingerprint).
 				WithField("issuer", issuer).
@@ -307,7 +404,7 @@ func ixHandshakeStage1(f *Interface, addr netip.AddrPort, via *ViaSender, packet
 				WithField("remoteIndex", h.RemoteIndex).WithField("handshake", m{"stage": 2, "style": "ix_psk0"}).
 				WithError(err).Error("Failed to send handshake")
 		} else {
-			f.l.WithField("vpnIp", vpnIp).WithField("udpAddr", addr).
+			f.l.WithField("vpnAddrs", vpnAddrs).WithField("udpAddr", addr).
 				WithField("certName", certName).
 				WithField("fingerprint", fingerprint).
 				WithField("issuer", issuer).
@@ -320,9 +417,12 @@ func ixHandshakeStage1(f *Interface, addr netip.AddrPort, via *ViaSender, packet
 			f.l.Error("Handshake send failed: both addr and via are nil.")
 			return
 		}
-		hostinfo.relayState.InsertRelayTo(via.relayHI.vpnIp)
+		hostinfo.relayState.InsertRelayTo(via.relayHI.vpnAddrs[0])
+		// I successfully received a handshake. Just in case I marked this tunnel as 'Disestablished', ensure
+		// it's correctly marked as working.
+		via.relayHI.relayState.UpdateRelayForByIdxState(via.remoteIdx, Established)
 		f.SendVia(via.relayHI, via.relay, msg, make([]byte, 12), make([]byte, mtu), false)
-		f.l.WithField("vpnIp", vpnIp).WithField("relay", via.relayHI.vpnIp).
+		f.l.WithField("vpnAddrs", vpnAddrs).WithField("relay", via.relayHI.vpnAddrs[0]).
 			WithField("certName", certName).
 			WithField("fingerprint", fingerprint).
 			WithField("issuer", issuer).
@@ -349,8 +449,9 @@ func ixHandshakeStage2(f *Interface, addr netip.AddrPort, via *ViaSender, hh *Ha

 	hostinfo := hh.hostinfo
 	if addr.IsValid() {
-		if !f.lightHouse.GetRemoteAllowList().Allow(hostinfo.vpnIp, addr.Addr()) {
-			f.l.WithField("vpnIp", hostinfo.vpnIp).WithField("udpAddr", addr).Debug("lighthouse.remote_allow_list denied incoming handshake")
+		// The vpnAddr we know about is the one we tried to handshake with, use it to apply the remote allow list.
+		if !f.lightHouse.GetRemoteAllowList().AllowAll(hostinfo.vpnAddrs, addr.Addr()) {
+			f.l.WithField("vpnAddrs", hostinfo.vpnAddrs).WithField("udpAddr", addr).Debug("lighthouse.remote_allow_list denied incoming handshake")
 			return false
 		}
 	}
@@ -358,7 +459,7 @@ func ixHandshakeStage2(f *Interface, addr netip.AddrPort, via *ViaSender, hh *Ha
 	ci := hostinfo.ConnectionState
 	msg, eKey, dKey, err := ci.H.ReadMessage(nil, packet[header.Len:])
 	if err != nil {
-		f.l.WithError(err).WithField("vpnIp", hostinfo.vpnIp).WithField("udpAddr", addr).
+		f.l.WithError(err).WithField("vpnAddrs", hostinfo.vpnAddrs).WithField("udpAddr", addr).
 			WithField("handshake", m{"stage": 2, "style": "ix_psk0"}).WithField("header", h).
 			Error("Failed to call noise.ReadMessage")

@@ -367,7 +468,7 @@ func ixHandshakeStage2(f *Interface, addr netip.AddrPort, via *ViaSender, hh *Ha
 		// near future
 		return false
 	} else if dKey == nil || eKey == nil {
-		f.l.WithField("vpnIp", hostinfo.vpnIp).WithField("udpAddr", addr).
+		f.l.WithField("vpnAddrs", hostinfo.vpnAddrs).WithField("udpAddr", addr).
 			WithField("handshake", m{"stage": 2, "style": "ix_psk0"}).
 			Error("Noise did not arrive at a key")

@@ -379,16 +480,16 @@ func ixHandshakeStage2(f *Interface, addr netip.AddrPort, via *ViaSender, hh *Ha
 	hs := &NebulaHandshake{}
 	err = hs.Unmarshal(msg)
 	if err != nil || hs.Details == nil {
-		f.l.WithError(err).WithField("vpnIp", hostinfo.vpnIp).WithField("udpAddr", addr).
+		f.l.WithError(err).WithField("vpnAddrs", hostinfo.vpnAddrs).WithField("udpAddr", addr).
 			WithField("handshake", m{"stage": 2, "style": "ix_psk0"}).Error("Failed unmarshal handshake message")

 		// The handshake state machine is complete, if things break now there is no chance to recover. Tear down and start again
 		return true
 	}

-	remoteCert, err := RecombineCertAndValidate(ci.H, hs.Details.Cert, f.pki.GetCAPool())
+	remoteCert, err := cert.RecombineAndValidate(cert.Version(hs.Details.CertVersion), hs.Details.Cert, ci.H.PeerStatic(), ci.Curve(), f.pki.GetCAPool())
 	if err != nil {
-		e := f.l.WithError(err).WithField("vpnIp", hostinfo.vpnIp).WithField("udpAddr", addr).
+		e := f.l.WithError(err).WithField("vpnAddrs", hostinfo.vpnAddrs).WithField("udpAddr", addr).
 			WithField("handshake", m{"stage": 2, "style": "ix_psk0"})

 		if f.l.Level > logrus.DebugLevel {
@@ -409,11 +510,11 @@ func ixHandshakeStage2(f *Interface, addr netip.AddrPort, via *ViaSender, hh *Ha
 			e = e.WithField("cert", remoteCert)
 		}

-		e.Info("Invalid vpn ip from host")
+		e.Info("Empty networks from host")
 		return true
 	}

-	vpnIp := remoteCert.Certificate.Networks()[0].Addr().Unmap()
+	vpnNetworks := remoteCert.Certificate.Networks()
 	certName := remoteCert.Certificate.Name()
 	fingerprint := remoteCert.Fingerprint
 	issuer := remoteCert.Certificate.Issuer()
@@ -430,12 +531,34 @@ func ixHandshakeStage2(f *Interface, addr netip.AddrPort, via *ViaSender, hh *Ha
 	if addr.IsValid() {
 		hostinfo.SetRemote(addr)
 	} else {
-		hostinfo.relayState.InsertRelayTo(via.relayHI.vpnIp)
+		hostinfo.relayState.InsertRelayTo(via.relayHI.vpnAddrs[0])
+	}
+
+	var vpnAddrs []netip.Addr
+	var filteredNetworks []netip.Prefix
+	for _, network := range vpnNetworks {
+		// vpnAddrs outside our vpn networks are of no use to us, filter them out
+		vpnAddr := network.Addr()
+		if _, ok := f.myVpnNetworksTable.Lookup(vpnAddr); !ok {
+			continue
+		}
+
+		filteredNetworks = append(filteredNetworks, network)
+		vpnAddrs = append(vpnAddrs, vpnAddr)
+	}
+
+	if len(vpnAddrs) == 0 {
+		f.l.WithError(err).WithField("udpAddr", addr).
+			WithField("certName", certName).
+			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
-	if vpnIp != hostinfo.vpnIp {
-		f.l.WithField("intendedVpnIp", hostinfo.vpnIp).WithField("haveVpnIp", vpnIp).
+	if !slices.Contains(vpnAddrs, hostinfo.vpnAddrs[0]) {
+		f.l.WithField("intendedVpnAddrs", hostinfo.vpnAddrs).WithField("haveVpnNetworks", vpnNetworks).
 			WithField("udpAddr", addr).WithField("certName", certName).
 			WithField("handshake", m{"stage": 2, "style": "ix_psk0"}).
 			Info("Incorrect host responded to handshake")
@@ -444,14 +567,13 @@ 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
-		f.handshakeManager.StartHandshake(hostinfo.vpnIp, func(newHH *HandshakeHostInfo) {
-			//TODO: this doesnt know if its being added or is being used for caching a packet
+		f.handshakeManager.StartHandshake(hostinfo.vpnAddrs[0], func(newHH *HandshakeHostInfo) {
 			// Block the current used address
 			newHH.hostinfo.remotes = hostinfo.remotes
 			newHH.hostinfo.remotes.BlockRemote(addr)

 			f.l.WithField("blockedUdpAddrs", newHH.hostinfo.remotes.CopyBlockedRemotes()).
-				WithField("vpnIp", newHH.hostinfo.vpnIp).
+				WithField("vpnNetworks", vpnNetworks).
 				WithField("remotes", newHH.hostinfo.remotes.CopyAddrs(f.hostMap.GetPreferredRanges())).
 				Info("Blocked addresses for handshakes")

@@ -459,11 +581,8 @@ func ixHandshakeStage2(f *Interface, addr netip.AddrPort, via *ViaSender, hh *Ha
 			newHH.packetStore = hh.packetStore
 			hh.packetStore = []*cachedPacket{}

-			// Get the correct remote list for the host we did handshake with
-			hostinfo.SetRemote(addr)
-			hostinfo.remotes = f.lightHouse.QueryCache(vpnIp)
-			// Finally, put the correct vpn ip in the host info, tell them to close the tunnel, and return true to tear down
-			hostinfo.vpnIp = vpnIp
+			// Finally, put the correct vpn addrs in the host info, tell them to close the tunnel, and return true to tear down
+			hostinfo.vpnAddrs = vpnAddrs
 			f.sendCloseTunnel(hostinfo)
 		})

@@ -474,7 +593,7 @@ 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("vpnIp", vpnIp).WithField("udpAddr", addr).
+	f.l.WithField("vpnAddrs", vpnAddrs).WithField("udpAddr", addr).
 		WithField("certName", certName).
 		WithField("fingerprint", fingerprint).
 		WithField("issuer", issuer).
@@ -485,9 +604,10 @@ func ixHandshakeStage2(f *Interface, addr netip.AddrPort, via *ViaSender, hh *Ha
 		Info("Handshake message received")

 	// Build up the radix for the firewall if we have subnets in the cert
-	hostinfo.CreateRemoteCIDR(remoteCert.Certificate)
+	hostinfo.vpnAddrs = vpnAddrs
+	hostinfo.buildNetworks(filteredNetworks, remoteCert.Certificate.UnsafeNetworks())

-	// Complete our handshake and update metrics, this will replace any existing tunnels for this vpnIp
+	// Complete our handshake and update metrics, this will replace any existing tunnels for the vpnAddrs here
 	f.handshakeManager.Complete(hostinfo, f)
 	f.connectionManager.AddTrafficWatch(hostinfo.localIndexId)