c++ - NAT-Traversal implementation for P2P connection -


i need implement simple p2p application behind nats. should send data on reliable , secure connection (encrypted data on tcp). theoretical background know there several nat-traversal techniques (for example session traversal utilities nat) described in several rfcs (5389, 5769, , 5780).

though in practice can't find needed tools/libraries implement such system (preferably in c++ programming language). found googling around blindly: ice, turn, libnice, libjingle , stuntman

below image describes should like. have vps valid ip address, pc behind nat , sensor behind nat. have private ips. want sensor connect server, find monitor , send connection request it. after connection establishment, relay server should not used direct traffic of data. want sensor , monitor use path communicate:

sensor <--> ap0 <--> r3 <--> {the internet} <--> r2 <--> monitor

currently data transmitted through vps:

sensor <--> ap0 <--> r3 <--> {the internet} r1 <-->  vps <--> r1 <--> {the internet} <--> r2 <--> monitor

network

‌

basically, if can port forward, more of infrastructure question programming. need configure routers direct traffic public ip / port private ip / port, e.g.:

r2: port 500 - tcp -> laptop-pt - port 500 r3: ports 16000/16500 - tcp/udp -> pda-pt - port 16000/16500

if want fancy , routers support upnp, resort library implements igd protocol (e.g., miniupnp), in order make application control port mapping. this article provides starting point sample code (although recommend robust library).


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