UDP Hole punching functional details

[madmax77]

Hello all,

I'm trying to setup NAT and I would like to enable full cone nat only on specific ports because of security reasons.

In order to make sure uTP/UDP Hole punching work, I would like to know if uTorrent use specific ports to implement this feature for nat traversal.

In particular I would like to know (if it's possible):

a) If you can confirm me a Public Peer is used as "STUN-like" server or in other words as RV server for the hole punching

if a well known source/destination port is used to communicate with this server (or the port specified in TCP incoming connection is used, or any other well known port)

c) if you could share details on how it works and if it's compatible with other hole punching implementations on other TorrentApps (such as Bittorrent, Vuze etc.).

Thanks a lot for your help.

[waseihou]

UDP multihole punching

Maybe this link could be useful for someone:

http://www.goto.info.waseda.ac.jp/~wei/file/wei-apan-v10.pdf

it describes an idea of "multihole punching" which should be able to connect two peers who are both behind symmetric NAT, it needs two servers with public IP address to work though.

I believe that this could be beneficial to developers and it fits into this thread. If this is already used, then please let us know.