Penetration Testing: Re: attack on a computer behind a nat.

[David Howe <DaveHowe.Pentest () googlemail com>]

Mark Owen wrote:
> Only problem with that is the firewall/router/nat won't be expecting a
> result from your IP address and will drop it as it would have no idea
> what computer behind the nat to forward it to.  If there is no
> underlying session, there is no communication. 
Most nats, particularly for udp, aren't that smart. they will accept a
packet "to" the natted outside IP+port and forward it to the internal
host. There are nat2nat session proxy servers that take advantage of
that - they accept two connections (from a:aport and b:bport) and tell
"a" to connect to b:bport and "b" to connect to a:aport. Mostly, this works.

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