Firewall Wizards mailing list archives

Re: Firewalls and 802.1q trunking


From: Luca Berra <bluca () comedia it>
Date: Wed, 04 Dec 2002 20:14:47 +0100

Eric Vyncke wrote:
First, have a look at my IP address to remove possible bias ;-)

Second, @stakes made some extended research on VLAN hopping against a Catalyst switch. They were unable to actually hop 
between VLAN on a well configured switch. See their paper on:
http://www.cisco.com/warp/public/cc/pd/si/casi/ca6000/tech/stake_wp.pdf

Having said this, I've seen two different points of view:

- misconfiguration happens: an Infosec or network operator can make a mistake in the VLAN configuration

- probabilty of faulty switch configuration by an educated network/infosec operator is less than the probability of a 
wrong cable patching in the datacom room by a uneducated engineer.

I guess that the decision really belongs to _your_ security policy and requirements.

I have another one to add to the list:
it happened twice here that after a power f**k-up a catalyst rebooted with default configuration (which means all port in default vlan)

since the default for a catalyst in this case is to switch traffic this situation (even if rare) is another point of concern.

btw wrong cable patching can in part be prevented by mac-address checks on the switch.

Regards,
Luca

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