On Sun, 21 Apr 2013 23:59:00 -0700 Rick Thomas <rbtho...@pobox.com> wrote:
> Alberto, > > What you want to do is possible. In particular, skype and bittorrent do it. > > As I understand it, they make use of a server with a public IP address. I'm > not going to get it exactly right, but the general idea is this: > > Two clients, A and B, both behind NAT firewalls. Server, S, with a public > IP, i.e. *not* behind NAT. > > A calls S and says I want to talk to B. (This is possible because the call > is originated inside A's NAT) > At approximately the same time, B calls S and says I'm willing to talk to A. > (Possible because call is originated inside B's NAT) > > Server tells each of A and B (over the connections each of them have open > with S) in exactly 1 second (or whenever) from receiving this packet, try to > open a connection to your opposite number on port 40000 (or whatever). > > With luck, each NAT will receive and act upon the outgoing request to setup > the connection *before* it receives the incoming request. So by the time the > incoming request is received, the channel will be open and ready to receive. > > If it doesn't work the first time, try again with slightly different timing. > > Keep trying until it does work -- or you get tired and quit. > > The result is a direct connection between A and B, which *both* NATs see as > having been started from inside. > > The server, S, is only involved for a brief time at the beginning. > > Other than skype and bittorrent, I'm not aware of any packages that do this. > Neither of them are directly useful for your purposes. > > It's possible that nat-traverse is a general purpose implementation of this > trick, but I haven't read the documentation, so I can't say for sure. Yes: http://m19s28.dyndns.org/iblech/nat-traverse/#technique General discussion: http://www.h-online.com/security/features/How-Skype-Co-get-round-firewalls-747197.html Celejar -- To UNSUBSCRIBE, email to debian-user-requ...@lists.debian.org with a subject of "unsubscribe". Trouble? Contact listmas...@lists.debian.org Archive: http://lists.debian.org/20130422075508.4caa8c8b.cele...@gmail.com
