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From: Stefan Monnier <monnier@iro.umontreal.ca>
Newsgroups: comp.os.linux.networking
Subject: Re: How could I get a connection to an UDP port through two NATs that I don't own?
Date: Wed, 15 Jun 2016 23:11:29 -0400
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> The NAT state will include the IP address of the common server and
> unless it is a very permissive NAT is unlikely to pass traffic with a
> different IP.

Check out STUN.  Indeed, it doesn't always work.  But it apparently
works with several home routers.  Don't know what kind of NAT is used by
the Linux kernel (i.e. by an OpenWRT router), tho.


        Stefan