RE: VALN hopping

["Steve McLaughlin" <Steve.McLaughlin () aggreko co uk>]

According to Cisco they are a good security measure.
I don't know of any exploits which enable you to VLAN hop.

Does anyone know of any?

On a layer 2 switch the ports are physically assigned to a VLAN, and
therefore require a Layer 3 device to route traffic between them.

On a layer 3 switch this might be different because of it's layer 3
capabilities built into the appliance. Though, I still don't know of any
way of 'VLAN Hopping', although I could be wrong.

And if this is possible on a layer 2 switch then please explain?

Steve McLaughlin - Security Analyst
(CCNP, MCSE:Security, Security+)

-----Original Message-----
From: David Barroso [mailto:dbarroso () s21sec com] 
Sent: 30 September 2005 18:54
To: Hayes, Ian
Cc: security-basics () securityfocus com
Subject: Re: VALN hopping

> WWe are having a heated discussion about using VLAN's as a type of
> DMZ, so
> > I am asking the experts.  I prsonally like to see physical
isolation;
> > however, our network person doesn't feel there is a threat of VLAN
> > hopping.  Please let me know your opinions.

If they are new devices with up-to-date OS versions it is not very
likely
that attacks similar to double encapsulated 802.1q packets will succeed.
On
the other hand, if they are not properly configured and/or hardened,
other
attacks can be accomplished, like for instance, with Cisco devices,
setting
up a trunking if DTP settings are poorly configured (see
http://yersinia.sourceforge.net for performing that attack).

--
David Barroso Berrueta 
Not one day goes by that I don't ride, 'til the infinite, the horse of
my imagination

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