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Re: ip tunnel ... mode gre -- encrypted? or not?



Hi will,

Quoth will trillich, 
> when a linux wonk says <with real IP's, of course>
> 	DEV=mytunnel
> 	OUTSIDE_HERE=321.1.2.3
> 	OUTSIDE_THERE=789.9.8.7
> 	ip tunnel add $DEV \
> 		local $OUTSIDE_HERE \
> 		remote $OUTSIDE_THERE \
> 		mode gre
> is the tunnel encrypted? if so, how can i confirm
> that? if not, is there a way to do so? (maybe some
> argument needs to be supplied to insmod?)

While I know very little about this VPN stuff (except port-forwarding
using ssh, but I've posted everything I know about that here anyway), I
would imagine that the easiest way to see if the traffic is encrypted or
not is to sniff it and see if it's sending cleartext.

Just use `sniffit -F mytunnel -i'. Telnet across your VPN, and select
that socket in the sniffit interactive window. Type something (like
uname -a) in the telnet session and see if you can see anything
recognisable.

This isn't very scientific, and I'd personally have a hard time telling
the difference between ROT-13'd and IDEA-encrypted traffic, but if you
can't see any cleartext, then it's probably working.

HTH,

damon

-- 
Damon Muller              | Did a large procession wave their torches
Criminologist/Linux Geek  | As my head fell in the basket,
http://killfilter.com     | And was everybody dancing on the casket...
PGP (GnuPG): A136E829     |                      - TBMG, "Dead"

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