[dcc2] NAT traversal for direct connections

[Dan Smith]

Hey everyone,

I have been updating the negotiation draft to address our last months 
discussion.  I think we still have more to talk about with the NAT traversal.

The current NAT token should be renamed to PASV or something similar, to 
indicate a passive transfer would be preferred, and be added as an option 
in a "new" NAT token.  The NAT token will then contain a list of supported 
NAT traversal protocols.  Which traversal techniques do you think we should 
adopt/standardize around?

The two that I am leaning toward are STUN+UPNP, and microsofts Teredo 
technique for IPv6 encapsulation over IPv4/UDP.

There are advantages and disadvantages to each.  With teredo, a 
intermediate teredo server (an ipv4 and ipv6 connected computer) is 
needed.  STUN does not allow incoming tcp connections or work with 
symmetric NATs, so connections would have to use a tftp type protocol over udp.

There is "no good way" to solve the problem of NAT traversal beside global 
addressing (which DCC2's ipv6 support addresses), but we can still solve of 
most of the NAT traversal cases.  What are your opinions/comments or other 
protocol suggestions?

Quicklinks:
http://www.microsoft.com/technet/prodtechnol/winxppro/maintain/teredo.mspx

http://www.ietf.org/rfc/rfc3489.txt

Cheers!
Dan


---------------------------
Dan Smith
+1 608-213-2867
Algenta Technologies, LLC