How/where is NAT traversal implemented?

[SpliFF]

Been looking through files in rts/System/ and rts/System/Net but not seeing anything related to hole punching or nat traversal. Does that mean it's handled by the lobbies? Also does LuaLobby support NAT traversal?

[abma]

exactly:

http://springrts.com/dl/LobbyProtocol/P ... NED:server

https://github.com/spring/SpringLS/blob ... nching.txt

and maybe: https://github.com/lunixbochs/uberserve ... l.py#L1297

[SpliFF]

Thanks, how about LuaLobby? I added that after you answered.

[abma]

hehe, edited my answer, too..

lualobby will be removed in the next release, superseded by LuaSocket

and no, it didn't support nat transversal (afaik)


to implement hole-punching you've just to regulary send an udp packet to the game host+port... HolePunching.txt should answer all questions i think

[SpliFF]

Thanks, I did mean LuaSocket.

My understanding is that for LuaSocket or other connections not already tunnelled by the lobby server I would need a STUN server or TURN server (symmetric NAT) or UPnP implementation.

I'll be running at least one public server so I have the basic requirements except for the actual code.

Note, your UDP example assumes the server is public, I'm talking about a server hosted behind a NAT. The server would need to discover it's own public IP using a public server and that is basically what STUN does. I'm guessing Spring lobbies do the same thing but using the lobby protocol instead of STUN.

[abma]

What do you want to do?

If i understood hole-punching right it works like this:

- lobby client S (spring server?!) connects with tcp to lobby.springrts.com:8200

- client S creates a battle saying i'm hole punching
- client X join
- lobby server sends ip/ports of X to client S
- client S sends udp packets to the known ip/ports

-> X should be able to connect to S...

what do you mean with tunnelled? afaik there is no tunnel? (tunnel in my understanding is to "tunnel" some connectiong trough a foreign / different protocol, like a tcp connection over a ssh session)

[a1983]

Host has local ip, behind the NAT that has external ip. TASServer should report in command BATTLEOPENED external ip. But when I create nat traversal battle in spring lobby, TASServer report local ip in BATTLEOPENED ( 192.168.x.x ). Thus hole punching failed.
Am I right, or hole punching work in other way?