Plumb through localInterfaceId to track local interfaces corresponding with remote addresses.

10 files changed, 89 insertions, 65 deletions

diff --git a/node/IncomingPacket.cpp b/node/IncomingPacket.cpp
index fc79270b..e4861af7 100644
--- a/node/IncomingPacket.cpp
+++ b/node/IncomingPacket.cpp
@@ -69,7 +69,7 @@ bool IncomingPacket::tryDecode(const RuntimeEnvironment *RR)
 			switch(verb()) {
 				//case Packet::VERB_NOP:
 				default: // ignore unknown verbs, but if they pass auth check they are "received"
-					peer->received(RR,_remoteAddress,hops(),packetId(),verb(),0,Packet::VERB_NOP);
+					peer->received(RR,_localInterfaceId,_remoteAddress,hops(),packetId(),verb(),0,Packet::VERB_NOP);
 					return true;
 				case Packet::VERB_HELLO:                          return _doHELLO(RR);
 				case Packet::VERB_ERROR:                          return _doERROR(RR,peer);
@@ -144,7 +144,7 @@ bool IncomingPacket::_doERROR(const RuntimeEnvironment *RR,const SharedPtr<Peer>
 						Packet outp(peer->address(),RR->identity.address(),Packet::VERB_NETWORK_MEMBERSHIP_CERTIFICATE);
 						nconf->com().serialize(outp);
 						outp.armor(peer->key(),true);
-						RR->node->putPacket(_remoteAddress,outp.data(),outp.size());
+						RR->node->putPacket(_localInterfaceId,_remoteAddress,outp.data(),outp.size());
 					}
 				}
 			}	break;
@@ -165,7 +165,7 @@ bool IncomingPacket::_doERROR(const RuntimeEnvironment *RR,const SharedPtr<Peer>
 			default: break;
 		}
 
-		peer->received(RR,_remoteAddress,hops(),packetId(),Packet::VERB_ERROR,inRePacketId,inReVerb);
+		peer->received(RR,_localInterfaceId,_remoteAddress,hops(),packetId(),Packet::VERB_ERROR,inRePacketId,inReVerb);
 	} catch (std::exception &ex) {
 		TRACE("dropped ERROR from %s(%s): unexpected exception: %s",source().toString().c_str(),_remoteAddress.toString().c_str(),ex.what());
 	} catch ( ... ) {
@@ -231,7 +231,7 @@ bool IncomingPacket::_doHELLO(const RuntimeEnvironment *RR)
 						outp.append(packetId());
 						outp.append((unsigned char)Packet::ERROR_IDENTITY_COLLISION);
 						outp.armor(key,true);
-						RR->node->putPacket(_remoteAddress,outp.data(),outp.size());
+						RR->node->putPacket(_localInterfaceId,_remoteAddress,outp.data(),outp.size());
 					} else {
 						RR->node->postEvent(ZT1_EVENT_AUTHENTICATION_FAILURE,(const void *)&_remoteAddress);
 						TRACE("rejected HELLO from %s(%s): packet failed authentication",id.address().toString().c_str(),_remoteAddress.toString().c_str());
@@ -278,7 +278,7 @@ bool IncomingPacket::_doHELLO(const RuntimeEnvironment *RR)
 
 		// VALID -- continues here
 
-		peer->received(RR,_remoteAddress,hops(),packetId(),Packet::VERB_HELLO,0,Packet::VERB_NOP);
+		peer->received(RR,_localInterfaceId,_remoteAddress,hops(),packetId(),Packet::VERB_HELLO,0,Packet::VERB_NOP);
 		peer->setRemoteVersion(protoVersion,vMajor,vMinor,vRevision);
 
 		bool trusted = false;
@@ -316,7 +316,7 @@ bool IncomingPacket::_doHELLO(const RuntimeEnvironment *RR)
 		}
 
 		outp.armor(peer->key(),true);
-		RR->node->putPacket(_remoteAddress,outp.data(),outp.size());
+		RR->node->putPacket(_localInterfaceId,_remoteAddress,outp.data(),outp.size());
 	} catch (std::exception &ex) {
 		TRACE("dropped HELLO from %s(%s): %s",source().toString().c_str(),_remoteAddress.toString().c_str(),ex.what());
 	} catch ( ... ) {
@@ -436,7 +436,7 @@ bool IncomingPacket::_doOK(const RuntimeEnvironment *RR,const SharedPtr<Peer> &p
 			default: break;
 		}
 
-		peer->received(RR,_remoteAddress,hops(),packetId(),Packet::VERB_OK,inRePacketId,inReVerb);
+		peer->received(RR,_localInterfaceId,_remoteAddress,hops(),packetId(),Packet::VERB_OK,inRePacketId,inReVerb);
 	} catch (std::exception &ex) {
 		TRACE("dropped OK from %s(%s): unexpected exception: %s",source().toString().c_str(),_remoteAddress.toString().c_str(),ex.what());
 	} catch ( ... ) {
@@ -456,7 +456,7 @@ bool IncomingPacket::_doWHOIS(const RuntimeEnvironment *RR,const SharedPtr<Peer>
 				outp.append(packetId());
 				queried->identity().serialize(outp,false);
 				outp.armor(peer->key(),true);
-				RR->node->putPacket(_remoteAddress,outp.data(),outp.size());
+				RR->node->putPacket(_localInterfaceId,_remoteAddress,outp.data(),outp.size());
 			} else {
 				Packet outp(peer->address(),RR->identity.address(),Packet::VERB_ERROR);
 				outp.append((unsigned char)Packet::VERB_WHOIS);
@@ -464,12 +464,12 @@ bool IncomingPacket::_doWHOIS(const RuntimeEnvironment *RR,const SharedPtr<Peer>
 				outp.append((unsigned char)Packet::ERROR_OBJ_NOT_FOUND);
 				outp.append(payload(),ZT_ADDRESS_LENGTH);
 				outp.armor(peer->key(),true);
-				RR->node->putPacket(_remoteAddress,outp.data(),outp.size());
+				RR->node->putPacket(_localInterfaceId,_remoteAddress,outp.data(),outp.size());
 			}
 		} else {
 			TRACE("dropped WHOIS from %s(%s): missing or invalid address",source().toString().c_str(),_remoteAddress.toString().c_str());
 		}
-		peer->received(RR,_remoteAddress,hops(),packetId(),Packet::VERB_WHOIS,0,Packet::VERB_NOP);
+		peer->received(RR,_localInterfaceId,_remoteAddress,hops(),packetId(),Packet::VERB_WHOIS,0,Packet::VERB_NOP);
 	} catch ( ... ) {
 		TRACE("dropped WHOIS from %s(%s): unexpected exception",source().toString().c_str(),_remoteAddress.toString().c_str());
 	}
@@ -487,8 +487,8 @@ bool IncomingPacket::_doRENDEZVOUS(const RuntimeEnvironment *RR,const SharedPtr<
 			if ((port > 0)&&((addrlen == 4)||(addrlen == 16))) {
 				InetAddress atAddr(field(ZT_PROTO_VERB_RENDEZVOUS_IDX_ADDRESS,addrlen),addrlen,port);
 				TRACE("RENDEZVOUS from %s says %s might be at %s, starting NAT-t",peer->address().toString().c_str(),with.toString().c_str(),atAddr.toString().c_str());
-				peer->received(RR,_remoteAddress,hops(),packetId(),Packet::VERB_RENDEZVOUS,0,Packet::VERB_NOP);
-				RR->sw->rendezvous(withPeer,atAddr);
+				peer->received(RR,_localInterfaceId,_remoteAddress,hops(),packetId(),Packet::VERB_RENDEZVOUS,0,Packet::VERB_NOP);
+				RR->sw->rendezvous(withPeer,_localInterfaceId,atAddr);
 			} else {
 				TRACE("dropped corrupt RENDEZVOUS from %s(%s) (bad address or port)",peer->address().toString().c_str(),_remoteAddress.toString().c_str());
 			}
@@ -525,7 +525,7 @@ bool IncomingPacket::_doFRAME(const RuntimeEnvironment *RR,const SharedPtr<Peer>
 				RR->node->putFrame(network->id(),MAC(peer->address(),network->id()),network->mac(),etherType,0,field(ZT_PROTO_VERB_FRAME_IDX_PAYLOAD,payloadLen),payloadLen);
 			}
 
-			peer->received(RR,_remoteAddress,hops(),packetId(),Packet::VERB_FRAME,0,Packet::VERB_NOP);
+			peer->received(RR,_localInterfaceId,_remoteAddress,hops(),packetId(),Packet::VERB_FRAME,0,Packet::VERB_NOP);
 		} else {
 			TRACE("dropped FRAME from %s(%s): we are not connected to network %.16llx",source().toString().c_str(),_remoteAddress.toString().c_str(),at<uint64_t>(ZT_PROTO_VERB_FRAME_IDX_NETWORK_ID));
 		}
@@ -602,7 +602,7 @@ bool IncomingPacket::_doEXT_FRAME(const RuntimeEnvironment *RR,const SharedPtr<P
 				RR->node->putFrame(network->id(),from,to,etherType,0,field(comLen + ZT_PROTO_VERB_EXT_FRAME_IDX_PAYLOAD,payloadLen),payloadLen);
 			}
 
-			peer->received(RR,_remoteAddress,hops(),packetId(),Packet::VERB_EXT_FRAME,0,Packet::VERB_NOP);
+			peer->received(RR,_localInterfaceId,_remoteAddress,hops(),packetId(),Packet::VERB_EXT_FRAME,0,Packet::VERB_NOP);
 		} else {
 			TRACE("dropped EXT_FRAME from %s(%s): we are not connected to network %.16llx",source().toString().c_str(),_remoteAddress.toString().c_str(),at<uint64_t>(ZT_PROTO_VERB_FRAME_IDX_NETWORK_ID));
 		}
@@ -623,7 +623,7 @@ bool IncomingPacket::_doMULTICAST_LIKE(const RuntimeEnvironment *RR,const Shared
 		for(unsigned int ptr=ZT_PACKET_IDX_PAYLOAD;ptr<size();ptr+=18)
 			RR->mc->add(now,at<uint64_t>(ptr),MulticastGroup(MAC(field(ptr + 8,6),6),at<uint32_t>(ptr + 14)),peer->address());
 
-		peer->received(RR,_remoteAddress,hops(),packetId(),Packet::VERB_MULTICAST_LIKE,0,Packet::VERB_NOP);
+		peer->received(RR,_localInterfaceId,_remoteAddress,hops(),packetId(),Packet::VERB_MULTICAST_LIKE,0,Packet::VERB_NOP);
 	} catch (std::exception &ex) {
 		TRACE("dropped MULTICAST_LIKE from %s(%s): unexpected exception: %s",source().toString().c_str(),_remoteAddress.toString().c_str(),ex.what());
 	} catch ( ... ) {
@@ -647,7 +647,7 @@ bool IncomingPacket::_doNETWORK_MEMBERSHIP_CERTIFICATE(const RuntimeEnvironment
 			}
 		}
 
-		peer->received(RR,_remoteAddress,hops(),packetId(),Packet::VERB_NETWORK_MEMBERSHIP_CERTIFICATE,0,Packet::VERB_NOP);
+		peer->received(RR,_localInterfaceId,_remoteAddress,hops(),packetId(),Packet::VERB_NETWORK_MEMBERSHIP_CERTIFICATE,0,Packet::VERB_NOP);
 	} catch (std::exception &ex) {
 		TRACE("dropped NETWORK_MEMBERSHIP_CERTIFICATE from %s(%s): unexpected exception: %s",source().toString().c_str(),_remoteAddress.toString().c_str(),ex.what());
 	} catch ( ... ) {
@@ -666,7 +666,7 @@ bool IncomingPacket::_doNETWORK_CONFIG_REQUEST(const RuntimeEnvironment *RR,cons
 
 		const unsigned int h = hops();
 		const uint64_t pid = packetId();
-		peer->received(RR,_remoteAddress,h,pid,Packet::VERB_NETWORK_CONFIG_REQUEST,0,Packet::VERB_NOP);
+		peer->received(RR,_localInterfaceId,_remoteAddress,h,pid,Packet::VERB_NETWORK_CONFIG_REQUEST,0,Packet::VERB_NOP);
 
 		if (RR->localNetworkController) {
 			Dictionary netconf;
@@ -688,7 +688,7 @@ bool IncomingPacket::_doNETWORK_CONFIG_REQUEST(const RuntimeEnvironment *RR,cons
 						if (outp.size() > ZT_PROTO_MAX_PACKET_LENGTH) {
 							TRACE("NETWORK_CONFIG_REQUEST failed: internal error: netconf size %u is too large",(unsigned int)netconfStr.length());
 						} else {
-							RR->node->putPacket(_remoteAddress,outp.data(),outp.size());
+							RR->node->putPacket(_localInterfaceId,_remoteAddress,outp.data(),outp.size());
 						}
 					}
 				}	break;
@@ -700,7 +700,7 @@ bool IncomingPacket::_doNETWORK_CONFIG_REQUEST(const RuntimeEnvironment *RR,cons
 					outp.append((unsigned char)Packet::ERROR_OBJ_NOT_FOUND);
 					outp.append(nwid);
 					outp.armor(peer->key(),true);
-					RR->node->putPacket(_remoteAddress,outp.data(),outp.size());
+					RR->node->putPacket(_localInterfaceId,_remoteAddress,outp.data(),outp.size());
 				}	break;
 
 				case NetworkController::NETCONF_QUERY_ACCESS_DENIED: {
@@ -710,7 +710,7 @@ bool IncomingPacket::_doNETWORK_CONFIG_REQUEST(const RuntimeEnvironment *RR,cons
 					outp.append((unsigned char)Packet::ERROR_NETWORK_ACCESS_DENIED_);
 					outp.append(nwid);
 					outp.armor(peer->key(),true);
-					RR->node->putPacket(_remoteAddress,outp.data(),outp.size());
+					RR->node->putPacket(_localInterfaceId,_remoteAddress,outp.data(),outp.size());
 				} break;
 
 				case NetworkController::NETCONF_QUERY_INTERNAL_SERVER_ERROR:
@@ -732,7 +732,7 @@ bool IncomingPacket::_doNETWORK_CONFIG_REQUEST(const RuntimeEnvironment *RR,cons
 			outp.append((unsigned char)Packet::ERROR_UNSUPPORTED_OPERATION);
 			outp.append(nwid);
 			outp.armor(peer->key(),true);
-			RR->node->putPacket(_remoteAddress,outp.data(),outp.size());
+			RR->node->putPacket(_localInterfaceId,_remoteAddress,outp.data(),outp.size());
 		}
 	} catch (std::exception &exc) {
 		TRACE("dropped NETWORK_CONFIG_REQUEST from %s(%s): unexpected exception: %s",source().toString().c_str(),_remoteAddress.toString().c_str(),exc.what());
@@ -753,7 +753,7 @@ bool IncomingPacket::_doNETWORK_CONFIG_REFRESH(const RuntimeEnvironment *RR,cons
 				nw->requestConfiguration();
 			ptr += 8;
 		}
-		peer->received(RR,_remoteAddress,hops(),packetId(),Packet::VERB_NETWORK_CONFIG_REFRESH,0,Packet::VERB_NOP);
+		peer->received(RR,_localInterfaceId,_remoteAddress,hops(),packetId(),Packet::VERB_NETWORK_CONFIG_REFRESH,0,Packet::VERB_NOP);
 	} catch (std::exception &exc) {
 		TRACE("dropped NETWORK_CONFIG_REFRESH from %s(%s): unexpected exception: %s",source().toString().c_str(),_remoteAddress.toString().c_str(),exc.what());
 	} catch ( ... ) {
@@ -780,11 +780,11 @@ bool IncomingPacket::_doMULTICAST_GATHER(const RuntimeEnvironment *RR,const Shar
 			outp.append((uint32_t)mg.adi());
 			if (RR->mc->gather(peer->address(),nwid,mg,outp,gatherLimit)) {
 				outp.armor(peer->key(),true);
-				RR->node->putPacket(_remoteAddress,outp.data(),outp.size());
+				RR->node->putPacket(_localInterfaceId,_remoteAddress,outp.data(),outp.size());
 			}
 		}
 
-		peer->received(RR,_remoteAddress,hops(),packetId(),Packet::VERB_MULTICAST_GATHER,0,Packet::VERB_NOP);
+		peer->received(RR,_localInterfaceId,_remoteAddress,hops(),packetId(),Packet::VERB_MULTICAST_GATHER,0,Packet::VERB_NOP);
 	} catch (std::exception &exc) {
 		TRACE("dropped MULTICAST_GATHER from %s(%s): unexpected exception: %s",source().toString().c_str(),_remoteAddress.toString().c_str(),exc.what());
 	} catch ( ... ) {
@@ -871,12 +871,12 @@ bool IncomingPacket::_doMULTICAST_FRAME(const RuntimeEnvironment *RR,const Share
 				outp.append((unsigned char)0x02); // flag 0x02 = contains gather results
 				if (RR->mc->gather(peer->address(),nwid,to,outp,gatherLimit)) {
 					outp.armor(peer->key(),true);
-					RR->node->putPacket(_remoteAddress,outp.data(),outp.size());
+					RR->node->putPacket(_localInterfaceId,_remoteAddress,outp.data(),outp.size());
 				}
 			}
 		} // else ignore -- not a member of this network
 
-		peer->received(RR,_remoteAddress,hops(),packetId(),Packet::VERB_MULTICAST_FRAME,0,Packet::VERB_NOP);
+		peer->received(RR,_localInterfaceId,_remoteAddress,hops(),packetId(),Packet::VERB_MULTICAST_FRAME,0,Packet::VERB_NOP);
 	} catch (std::exception &exc) {
 		TRACE("dropped MULTICAST_FRAME from %s(%s): unexpected exception: %s",source().toString().c_str(),_remoteAddress.toString().c_str(),exc.what());
 	} catch ( ... ) {
@@ -905,14 +905,14 @@ bool IncomingPacket::_doPUSH_DIRECT_PATHS(const RuntimeEnvironment *RR,const Sha
 					InetAddress a(field(ptr,4),4,at<uint16_t>(ptr + 4));
 					if ( ((flags & (0x01 | 0x02)) == 0) && (Path::isAddressValidForPath(a)) ) {
 						TRACE("attempting to contact %s at pushed direct path %s",peer->address().toString().c_str(),a.toString().c_str());
-						peer->attemptToContactAt(RR,a,RR->node->now());
+						peer->attemptToContactAt(RR,_localInterfaceId,a,RR->node->now());
 					}
 				}	break;
 				case 6: {
 					InetAddress a(field(ptr,16),16,at<uint16_t>(ptr + 16));
 					if ( ((flags & (0x01 | 0x02)) == 0) && (Path::isAddressValidForPath(a)) ) {
 						TRACE("attempting to contact %s at pushed direct path %s",peer->address().toString().c_str(),a.toString().c_str());
-						peer->attemptToContactAt(RR,a,RR->node->now());
+						peer->attemptToContactAt(RR,_localInterfaceId,a,RR->node->now());
 					}
 				}	break;
 			}
@@ -934,7 +934,7 @@ void IncomingPacket::_sendErrorNeedCertificate(const RuntimeEnvironment *RR,cons
 	outp.append((unsigned char)Packet::ERROR_NEED_MEMBERSHIP_CERTIFICATE);
 	outp.append(nwid);
 	outp.armor(peer->key(),true);
-	RR->node->putPacket(_remoteAddress,outp.data(),outp.size());
+	RR->node->putPacket(_localInterfaceId,_remoteAddress,outp.data(),outp.size());
 }
 
 } // namespace ZeroTier
diff --git a/node/IncomingPacket.hpp b/node/IncomingPacket.hpp
index 3bf7737d..170ab7f9 100644
--- a/node/IncomingPacket.hpp
+++ b/node/IncomingPacket.hpp
@@ -72,14 +72,16 @@ public:
 	 *
 	 * @param data Packet data
 	 * @param len Packet length
+	 * @param localInterfaceId Local interface ID
 	 * @param remoteAddress Address from which packet came
 	 * @param now Current time
 	 * @throws std::out_of_range Range error processing packet
 	 */
-	IncomingPacket(const void *data,unsigned int len,const InetAddress &remoteAddress,uint64_t now) :
+	IncomingPacket(const void *data,unsigned int len,int localInterfaceId,const InetAddress &remoteAddress,uint64_t now) :
  		Packet(data,len),
  		_receiveTime(now),
  		_remoteAddress(remoteAddress),
+ 		_localInterfaceId(localInterfaceId),
  		__refCount()
 	{
 	}
@@ -128,6 +130,7 @@ private:
 
 	uint64_t _receiveTime;
 	InetAddress _remoteAddress;
+	int _localInterfaceId;
 	AtomicCounter __refCount;
 };
 
diff --git a/node/Node.cpp b/node/Node.cpp
index c8c50d66..f9559ab4 100644
--- a/node/Node.cpp
+++ b/node/Node.cpp
@@ -157,13 +157,14 @@ Node::~Node()
 
 ZT1_ResultCode Node::processWirePacket(
 	uint64_t now,
+	int localInterfaceId,
 	const struct sockaddr_storage *remoteAddress,
 	const void *packetData,
 	unsigned int packetLength,
 	volatile uint64_t *nextBackgroundTaskDeadline)
 {
 	_now = now;
-	RR->sw->onRemotePacket(*(reinterpret_cast<const InetAddress *>(remoteAddress)),packetData,packetLength);
+	RR->sw->onRemotePacket(localInterfaceId,*(reinterpret_cast<const InetAddress *>(remoteAddress)),packetData,packetLength);
 	return ZT1_RESULT_OK;
 }
 
@@ -261,7 +262,7 @@ ZT1_ResultCode Node::processBackgroundTasks(uint64_t now,volatile uint64_t *next
 				if (nr->second) {
 					SharedPtr<Peer> rp(RR->topology->getPeer(nr->first));
 					if ((rp)&&(!rp->hasActiveDirectPath(now)))
-						rp->attemptToContactAt(RR,nr->second,now);
+						rp->attemptToContactAt(RR,-1,nr->second,now);
 				}
 			}
 
@@ -569,13 +570,14 @@ void ZT1_Node_delete(ZT1_Node *node)
 enum ZT1_ResultCode ZT1_Node_processWirePacket(
 	ZT1_Node *node,
 	uint64_t now,
+	int localInterfaceId,
 	const struct sockaddr_storage *remoteAddress,
 	const void *packetData,
 	unsigned int packetLength,
 	volatile uint64_t *nextBackgroundTaskDeadline)
 {
 	try {
-		return reinterpret_cast<ZeroTier::Node *>(node)->processWirePacket(now,remoteAddress,packetData,packetLength,nextBackgroundTaskDeadline);
+		return reinterpret_cast<ZeroTier::Node *>(node)->processWirePacket(now,localInterfaceId,remoteAddress,packetData,packetLength,nextBackgroundTaskDeadline);
 	} catch (std::bad_alloc &exc) {
 		return ZT1_RESULT_FATAL_ERROR_OUT_OF_MEMORY;
 	} catch ( ... ) {
diff --git a/node/Node.hpp b/node/Node.hpp
index 2a283eab..0e614e5a 100644
--- a/node/Node.hpp
+++ b/node/Node.hpp
@@ -80,6 +80,7 @@ public:
 
 	ZT1_ResultCode processWirePacket(
 		uint64_t now,
+		int localInterfaceId,
 		const struct sockaddr_storage *remoteAddress,
 		const void *packetData,
 		unsigned int packetLength,
@@ -119,16 +120,18 @@ public:
 	/**
 	 * Enqueue a ZeroTier message to be sent
 	 *
+	 * @param localInterfaceId Local interface ID, -1 for unspecified/random
 	 * @param addr Destination address
 	 * @param data Packet data
 	 * @param len Packet length
 	 * @return True if packet appears to have been sent
 	 */
-	inline bool putPacket(const InetAddress &addr,const void *data,unsigned int len)
+	inline bool putPacket(int localInterfaceId,const InetAddress &addr,const void *data,unsigned int len)
 	{
 		return (_wirePacketSendFunction(
 			reinterpret_cast<ZT1_Node *>(this),
 			_uPtr,
+			localInterfaceId,
 			reinterpret_cast<const struct sockaddr_storage *>(&addr),
 			data,
 			len) == 0);
diff --git a/node/Peer.cpp b/node/Peer.cpp
index 05b14da0..e966a9bf 100644
--- a/node/Peer.cpp
+++ b/node/Peer.cpp
@@ -64,6 +64,7 @@ Peer::Peer(const Identity &myIdentity,const Identity &peerIdentity)
 
 void Peer::received(
 	const RuntimeEnvironment *RR,
+	int localInterfaceId,
 	const InetAddress &remoteAddr,
 	unsigned int hops,
 	uint64_t packetId,
@@ -81,7 +82,7 @@ void Peer::received(
 		{
 			unsigned int np = _numPaths;
 			for(unsigned int p=0;p<np;++p) {
-				if (_paths[p].address() == remoteAddr) {
+				if ((_paths[p].address() == remoteAddr)&&(_paths[p].localInterfaceId() == localInterfaceId)) {
 					_paths[p].received(now);
 					pathIsConfirmed = true;
 					break;
@@ -106,7 +107,7 @@ void Peer::received(
 						}
 					}
 					if (slot) {
-						*slot = RemotePath(remoteAddr,false);
+						*slot = RemotePath(localInterfaceId,remoteAddr,false);
 						slot->received(now);
 						_numPaths = np;
 						pathIsConfirmed = true;
@@ -119,7 +120,7 @@ void Peer::received(
 					if ((now - _lastPathConfirmationSent) >= ZT_MIN_PATH_CONFIRMATION_INTERVAL) {
 						_lastPathConfirmationSent = now;
 						TRACE("got %s via unknown path %s(%s), confirming...",Packet::verbString(verb),_id.address().toString().c_str(),remoteAddr.toString().c_str());
-						attemptToContactAt(RR,remoteAddr,now);
+						attemptToContactAt(RR,localInterfaceId,remoteAddr,now);
 					}
 				}
 			}
@@ -141,7 +142,7 @@ void Peer::received(
 					for(std::vector<MulticastGroup>::const_iterator mg(mgs.begin());mg!=mgs.end();++mg) {
 						if ((outp.size() + 18) > ZT_UDP_DEFAULT_PAYLOAD_MTU) {
 							outp.armor(_key,true);
-							RR->node->putPacket(remoteAddr,outp.data(),outp.size());
+							RR->node->putPacket(localInterfaceId,remoteAddr,outp.data(),outp.size());
 							outp.reset(_id.address(),RR->identity.address(),Packet::VERB_MULTICAST_LIKE);
 						}
 
@@ -154,7 +155,7 @@ void Peer::received(
 			}
 			if (outp.size() > ZT_PROTO_MIN_PACKET_LENGTH) {
 				outp.armor(_key,true);
-				RR->node->putPacket(remoteAddr,outp.data(),outp.size());
+				RR->node->putPacket(localInterfaceId,remoteAddr,outp.data(),outp.size());
 			}
 		}
 	}
@@ -180,7 +181,7 @@ RemotePath *Peer::getBestPath(uint64_t now)
 	return bestPath;
 }
 
-void Peer::attemptToContactAt(const RuntimeEnvironment *RR,const InetAddress &atAddress,uint64_t now)
+void Peer::attemptToContactAt(const RuntimeEnvironment *RR,int localInterfaceId,const InetAddress &atAddress,uint64_t now)
 {
 	Packet outp(_id.address(),RR->identity.address(),Packet::VERB_HELLO);
 	outp.append((unsigned char)ZT_PROTO_VERSION);
@@ -208,7 +209,7 @@ void Peer::attemptToContactAt(const RuntimeEnvironment *RR,const InetAddress &at
 	}
 
 	outp.armor(_key,false); // HELLO is sent in the clear
-	RR->node->putPacket(atAddress,outp.data(),outp.size());
+	RR->node->putPacket(localInterfaceId,atAddress,outp.data(),outp.size());
 }
 
 void Peer::doPingAndKeepalive(const RuntimeEnvironment *RR,uint64_t now)
@@ -217,12 +218,12 @@ void Peer::doPingAndKeepalive(const RuntimeEnvironment *RR,uint64_t now)
 	if (bestPath) {
 		if ((now - bestPath->lastReceived()) >= ZT_PEER_DIRECT_PING_DELAY) {
 			TRACE("PING %s(%s)",_id.address().toString().c_str(),bestPath->address().toString().c_str());
-			attemptToContactAt(RR,bestPath->address(),now);
+			attemptToContactAt(RR,bestPath->localInterfaceId(),bestPath->address(),now);
 			bestPath->sent(now);
 		} else if (((now - bestPath->lastSend()) >= ZT_NAT_KEEPALIVE_DELAY)&&(!bestPath->reliable())) {
 			_natKeepaliveBuf += (uint32_t)((now * 0x9e3779b1) >> 1); // tumble this around to send constantly varying (meaningless) payloads
 			TRACE("NAT keepalive %s(%s)",_id.address().toString().c_str(),bestPath->address().toString().c_str());
-			RR->node->putPacket(bestPath->address(),&_natKeepaliveBuf,sizeof(_natKeepaliveBuf));
+			RR->node->putPacket(bestPath->localInterfaceId(),bestPath->address(),&_natKeepaliveBuf,sizeof(_natKeepaliveBuf));
 			bestPath->sent(now);
 		}
 	}
@@ -354,7 +355,7 @@ bool Peer::resetWithinScope(const RuntimeEnvironment *RR,InetAddress::IpScope sc
 	while (x < np) {
 		if (_paths[x].address().ipScope() == scope) {
 			if (_paths[x].fixed()) {
-				attemptToContactAt(RR,_paths[x].address(),now);
+				attemptToContactAt(RR,_paths[x].localInterfaceId(),_paths[x].address(),now);
 				_paths[y++] = _paths[x]; // keep fixed paths
 			}
 		} else {
diff --git a/node/Peer.hpp b/node/Peer.hpp
index ef436cd9..b0f2b4e2 100644
--- a/node/Peer.hpp
+++ b/node/Peer.hpp
@@ -105,6 +105,7 @@ public:
 	 * and appears to be valid.
 	 *
 	 * @param RR Runtime environment
+	 * @param localInterfaceId Local interface ID or -1 if unspecified
 	 * @param remoteAddr Internet address of sender
 	 * @param hops ZeroTier (not IP) hops
 	 * @param packetId Packet ID
@@ -114,6 +115,7 @@ public:
 	 */
 	void received(
 		const RuntimeEnvironment *RR,
+		int localInterfaceId,
 		const InetAddress &remoteAddr,
 		unsigned int hops,
 		uint64_t packetId,
@@ -155,10 +157,11 @@ public:
 	 * for NAT traversal and path verification.
 	 *
 	 * @param RR Runtime environment
+	 * @param localInterfaceId Local interface ID or -1 for unspecified
 	 * @param atAddress Destination address
 	 * @param now Current time
 	 */
-	void attemptToContactAt(const RuntimeEnvironment *RR,const InetAddress &atAddress,uint64_t now);
+	void attemptToContactAt(const RuntimeEnvironment *RR,int localInterfaceId,const InetAddress &atAddress,uint64_t now);
 
 	/**
 	 * Send pings or keepalives depending on configured timeouts
diff --git a/node/RemotePath.hpp b/node/RemotePath.hpp
index 291943c9..a7ef141b 100644
--- a/node/RemotePath.hpp
+++ b/node/RemotePath.hpp
@@ -53,14 +53,18 @@ public:
 		Path(),
 		_lastSend(0),
 		_lastReceived(0),
+		_localInterfaceId(-1),
 		_fixed(false) {}
 
-	RemotePath(const InetAddress &addr,bool fixed) :
+	RemotePath(int localInterfaceId,const InetAddress &addr,bool fixed) :
 		Path(addr,0,TRUST_NORMAL),
 		_lastSend(0),
 		_lastReceived(0),
+		_localInterfaceId(localInterfaceId),
 		_fixed(fixed) {}
 
+	inline int localInterfaceId() const throw() { return _localInterfaceId; }
+
 	inline uint64_t lastSend() const throw() { return _lastSend; }
 	inline uint64_t lastReceived() const throw() { return _lastReceived; }
 
@@ -123,7 +127,7 @@ public:
 	 */
 	inline bool send(const RuntimeEnvironment *RR,const void *data,unsigned int len,uint64_t now)
 	{
-		if (RR->node->putPacket(address(),data,len)) {
+		if (RR->node->putPacket(_localInterfaceId,address(),data,len)) {
 			sent(now);
 			RR->antiRec->logOutgoingZT(data,len);
 			return true;
@@ -134,6 +138,7 @@ public:
 private:
 	uint64_t _lastSend;
 	uint64_t _lastReceived;
+	int _localInterfaceId;
 	bool _fixed;
 };
 
diff --git a/node/Switch.cpp b/node/Switch.cpp
index 995abef4..0de94400 100644
--- a/node/Switch.cpp
+++ b/node/Switch.cpp
@@ -78,8 +78,11 @@ Switch::~Switch()
 {
 }
 
-void Switch::onRemotePacket(const InetAddress &fromAddr,const void *data,unsigned int len)
+void Switch::onRemotePacket(int localInterfaceId,const InetAddress &fromAddr,const void *data,unsigned int len)
 {
+	if (localInterfaceId < 0)
+		localInterfaceId = 0;
+
 	try {
 		if (len == 13) {
 			/* LEGACY: before VERB_PUSH_DIRECT_PATHS, peers used broadcast
@@ -96,14 +99,14 @@ void Switch::onRemotePacket(const InetAddress &fromAddr,const void *data,unsigne
 					_lastBeaconResponse = now;
 					Packet outp(peer->address(),RR->identity.address(),Packet::VERB_NOP);
 					outp.armor(peer->key(),false);
-					RR->node->putPacket(fromAddr,outp.data(),outp.size());
+					RR->node->putPacket(localInterfaceId,fromAddr,outp.data(),outp.size());
 				}
 			}
 		} else if (len > ZT_PROTO_MIN_FRAGMENT_LENGTH) {
 			if (((const unsigned char *)data)[ZT_PACKET_FRAGMENT_IDX_FRAGMENT_INDICATOR] == ZT_PACKET_FRAGMENT_INDICATOR) {
-				_handleRemotePacketFragment(fromAddr,data,len);
+				_handleRemotePacketFragment(localInterfaceId,fromAddr,data,len);
 			} else if (len >= ZT_PROTO_MIN_PACKET_LENGTH) {
-				_handleRemotePacketHead(fromAddr,data,len);
+				_handleRemotePacketHead(localInterfaceId,fromAddr,data,len);
 			}
 		}
 	} catch (std::exception &ex) {
@@ -376,14 +379,14 @@ bool Switch::unite(const Address &p1,const Address &p2,bool force)
 	return true;
 }
 
-void Switch::rendezvous(const SharedPtr<Peer> &peer,const InetAddress &atAddr)
+void Switch::rendezvous(const SharedPtr<Peer> &peer,int localInterfaceId,const InetAddress &atAddr)
 {
 	TRACE("sending NAT-t message to %s(%s)",peer->address().toString().c_str(),atAddr.toString().c_str());
 	const uint64_t now = RR->node->now();
-	peer->attemptToContactAt(RR,atAddr,now);
+	peer->attemptToContactAt(RR,localInterfaceId,atAddr,now);
 	{
 		Mutex::Lock _l(_contactQueue_m);
-		_contactQueue.push_back(ContactQueueEntry(peer,now + ZT_NAT_T_TACTICAL_ESCALATION_DELAY,atAddr));
+		_contactQueue.push_back(ContactQueueEntry(peer,now + ZT_NAT_T_TACTICAL_ESCALATION_DELAY,localInterfaceId,atAddr));
 	}
 }
 
@@ -453,14 +456,14 @@ unsigned long Switch::doTimerTasks(uint64_t now)
 				} else {
 					if (qi->strategyIteration == 0) {
 						// First strategy: send packet directly to destination
-						qi->peer->attemptToContactAt(RR,qi->inaddr,now);
+						qi->peer->attemptToContactAt(RR,qi->localInterfaceId,qi->inaddr,now);
 					} else if (qi->strategyIteration <= 4) {
 						// Strategies 1-4: try escalating ports for symmetric NATs that remap sequentially
 						InetAddress tmpaddr(qi->inaddr);
 						int p = (int)qi->inaddr.port() + qi->strategyIteration;
 						if (p < 0xffff) {
 							tmpaddr.setPort((unsigned int)p);
-							qi->peer->attemptToContactAt(RR,tmpaddr,now);
+							qi->peer->attemptToContactAt(RR,qi->localInterfaceId,tmpaddr,now);
 						} else qi->strategyIteration = 5;
 					} else {
 						// All strategies tried, expire entry
@@ -551,7 +554,7 @@ unsigned long Switch::doTimerTasks(uint64_t now)
 	return nextDelay;
 }
 
-void Switch::_handleRemotePacketFragment(const InetAddress &fromAddr,const void *data,unsigned int len)
+void Switch::_handleRemotePacketFragment(int localInterfaceId,const InetAddress &fromAddr,const void *data,unsigned int len)
 {
 	Packet::Fragment fragment(data,len);
 	Address destination(fragment.destination());
@@ -622,9 +625,9 @@ void Switch::_handleRemotePacketFragment(const InetAddress &fromAddr,const void
 	}
 }
 
-void Switch::_handleRemotePacketHead(const InetAddress &fromAddr,const void *data,unsigned int len)
+void Switch::_handleRemotePacketHead(int localInterfaceId,const InetAddress &fromAddr,const void *data,unsigned int len)
 {
-	SharedPtr<IncomingPacket> packet(new IncomingPacket(data,len,fromAddr,RR->node->now()));
+	SharedPtr<IncomingPacket> packet(new IncomingPacket(data,len,localInterfaceId,fromAddr,RR->node->now()));
 
 	Address source(packet->source());
 	Address destination(packet->destination());
diff --git a/node/Switch.hpp b/node/Switch.hpp
index 55e2c362..a8d89f41 100644
--- a/node/Switch.hpp
+++ b/node/Switch.hpp
@@ -79,11 +79,12 @@ public:
 	/**
 	 * Called when a packet is received from the real network
 	 *
+	 * @param localInterfaceId Local interface ID or -1 for unspecified
 	 * @param fromAddr Internet IP address of origin
 	 * @param data Packet data
 	 * @param len Packet length
 	 */
-	void onRemotePacket(const InetAddress &fromAddr,const void *data,unsigned int len);
+	void onRemotePacket(int localInterfaceId,const InetAddress &fromAddr,const void *data,unsigned int len);
 
 	/**
 	 * Called when a packet comes from a local Ethernet tap
@@ -140,9 +141,10 @@ public:
 	 * Attempt NAT traversal to peer at a given physical address
 	 *
 	 * @param peer Peer to contact
+	 * @param localInterfaceId Local interface ID or -1 if unspecified
 	 * @param atAddr Address of peer
 	 */
-	void rendezvous(const SharedPtr<Peer> &peer,const InetAddress &atAddr);
+	void rendezvous(const SharedPtr<Peer> &peer,int localInterfaceId,const InetAddress &atAddr);
 
 	/**
 	 * Request WHOIS on a given address
@@ -179,8 +181,8 @@ public:
 	unsigned long doTimerTasks(uint64_t now);
 
 private:
-	void _handleRemotePacketFragment(const InetAddress &fromAddr,const void *data,unsigned int len);
-	void _handleRemotePacketHead(const InetAddress &fromAddr,const void *data,unsigned int len);
+	void _handleRemotePacketFragment(int localInterfaceId,const InetAddress &fromAddr,const void *data,unsigned int len);
+	void _handleRemotePacketHead(int localInterfaceId,const InetAddress &fromAddr,const void *data,unsigned int len);
 	Address _sendWhoisRequest(const Address &addr,const Address *peersAlreadyConsulted,unsigned int numPeersAlreadyConsulted);
 	bool _trySend(const Packet &packet,bool encrypt,uint64_t nwid);
 
@@ -260,15 +262,17 @@ private:
 	struct ContactQueueEntry
 	{
 		ContactQueueEntry() {}
-		ContactQueueEntry(const SharedPtr<Peer> &p,uint64_t ft,const InetAddress &a) :
+		ContactQueueEntry(const SharedPtr<Peer> &p,uint64_t ft,int liid,const InetAddress &a) :
 			peer(p),
 			fireAtTime(ft),
 			inaddr(a),
+			localInterfaceId(liid),
 			strategyIteration(0) {}
 
 		SharedPtr<Peer> peer;
 		uint64_t fireAtTime;
 		InetAddress inaddr;
+		int localInterfaceId;
 		unsigned int strategyIteration;
 	};
 	std::list<ContactQueueEntry> _contactQueue;
diff --git a/node/Topology.cpp b/node/Topology.cpp
index 25a92acd..c63ed9f4 100644
--- a/node/Topology.cpp
+++ b/node/Topology.cpp
@@ -62,7 +62,7 @@ void Topology::setRootServers(const std::map< Identity,std::vector<InetAddress>
 			if (!p)
 				p = SharedPtr<Peer>(new Peer(RR->identity,i->first));
 			for(std::vector<InetAddress>::const_iterator j(i->second.begin());j!=i->second.end();++j)
-				p->addPath(RemotePath(*j,true));
+				p->addPath(RemotePath(0,*j,true));
 			p->use(now);
 			_rootPeers.push_back(p);
 		}