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Date: Sun, 27 Nov 2005 14:21:02 -0800
From: Julian Elischer <julian@elischer.org>
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To: Brian Candler <B.Candler@pobox.com>
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Cc: net@freebsd.org
Subject: Re: proposal:  TCP rendevous
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Brian Candler wrote:

>On Sat, Nov 26, 2005 at 10:18:49PM -0800, Julian Elischer wrote:
>  
>
>>In this world of P2P apps it would be neat to have a way that two P2P apps
>>could attach to each other even though each is through a firewall. Most 
>>firewalls only allow
>>"outgoing" connections.
>>
>>It would of course be possible via a 3rd party relaying but that is 
>>inneffieient and the throughput
>>would be limited by throughput limits on the 3rd party link.
>>
>>It must be possible, with the connivance of a 3rd party both parties 
>>could be able
>>to make suitable 'OUTGOING' connections.
>>The 3rd party would spoof needed packets using information supplied
>>by the two parties.
>>    
>>
>
>See this: http://samy.pl/chownat/
>
>(Haven't tried it myself, but came across it on Freshmeat a while ago. I
>imagine it must rely on the NAT firewalls not changing the source UDP port
>unless they have to)
>  
>
yes, which means it might unexpectedly fail.