There was recently (July '07) a big discussion on this topic on the BEHAVE mailing list. I posted some of my results here:
http://www1.ietf.org/mail-archive/web/behave/current/msg02496.html Basically, I can get about direct 90% peer connectivity using UDP. Rumor is Alex can get something like 99% (Alex - care to share any detailed numbers?). The IETF is pushing a protocol named ICE, but nobody knows how well it works (Adam - have you come up with any numbers yet?). Overall, it's much harder than it looks, even in the "simple" cases. The basic algorithm is: 1) Figure out the IP address of each node's NAT 2) Share each node's pair of (LAN,NAT) IPs with the other node via some central server 3) Try to connect over both the LAN and NAT addresses. 4) Apply a lot of voodoo tricks 5) Oftentimes it works Everybody seems to use a variation on this algorithm, though Alex recently made some suspicious comments suggesting otherwise. -david _____ From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Carlos Kamienski Sent: Saturday, September 01, 2007 9:43 AM To: [email protected] Subject: [p2p-hackers] Effective TCP and UDP NAT Traversal (no relaying) Dear all, I'd like to know what type of experiences you have about the rate of succesfull direct communications (without relaying) of peers behind NAT, both for TCP and UDP and for different scenarios, like home and corporate users. There are some results reported like the one for STUNT (http://nutss.net/pub/imc05-tcpnat.pdf), which says that "TCP NAT Traversal can work 85%-90% of the time" ( http://www1.ietf.org/mail-archive/web/midcom/current/msg03848.html). However, other reports don't seem to be so encouraging, like http://www.paradial.com/storage/Elements/CallCompletion.pdf. What are the best approaches for TCP and UDP? STUN, STUNT, ICE,....? The thing is that we need peers to establish direct communication (no realying) for both TCP and UDPand I like to know the best approaches to do that and the best existing solutions for that. Thanks Carlos -- "There's no sense in being precise when you don't even know what you're talking about." John von Neumann
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