full-disclosure - ICMP Covert channels question

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Message-ID: <1ede00f705013006247ad82427@mail.gmail.com>
From: cyberpixl at gmail.com (cyberpixl)
Subject: ICMP Covert channels question

> 
> No, because non-routeable addresses are...well....non-routeable.  The only
> exception to this is *if* the target machine already had a session going
> with 33.33.33.33 (and it would obviously be nat'd/pat'd) there is a snort
> time frame within with your icmp packet would be delivered because the
> firewall is still translating the address/port for that session.
> 
> Of course you have to know in advance all those variables, so, since you're
> sitting right there, just pound the dern thing with a hammer and be done
> with it.  :-)
> 
> Paul Schmehl (pauls@...allas.edu)
> Adjunct Information Security Officer
> The University of Texas at Dallas
> AVIEN Founding Member
> http://www.utdallas.edu
> 

Well, what i meant was what if i use the networks router as a bounce
host in order to get the packets into the network? If an icmp packet
arrives at routers wan port with a source ip of an internal host will
it send the echoreply to its lan port? I currently haven't got the
chance to test this, but i will as soon as i can. Then, in order to
receive replyes from the host behind the firewall all I'd have to do
is make it send packets to a bounce server outsede the network, like
google.com with source set to my ip (assuming then that the router
freely allows icmp traffic out of the network).