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List:       vuln-dev
Subject:    Re: GATEWAY ?
From:       M Schubert <schubert () fsck ! org>
Date:       2000-12-23 10:36:20
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> I'm behind a NOMADIX USG which restrict users from accessing the
> internet w/ out a valid username password.

I'm assuming this is a proxy...

> Once you enter the
> username/pass it will never ask you for it again.  It remembers your
> MAC address and let you through each time after that. If a new mac
> address was to enter the network it would ask for user/pass combo..
> this is my ?, is it possible to fool this device into letting a MAC
> address through w/out a valid user/pass. If a change my MAC address
> to one that was already verify that work, but is there another way.

There software for linux that allows you to spoof your MAC address that
I am aware of.

http://packetstorm.securify.com/spoof/unix-spoof-code/changemac.c

However you do have to take into consideration if you spoofed the MAC
of another machine on the network and both machines tried to go through
the proxy... well that wouldn't work (packets would not be returned to
the right client), the other machine would have to be off, disconnected
or even muted (read: packet flooded), none of which are good ideas if
you value your current employment.

>  by the way all computers inside the LAN share the same IP address
> once it get through this USG device also it is probally the gateway.

So we know that its doing NATing obviously, but does it matter if your
IP changes?

--
-- M. Schubert          - mschuber@uci.edu
-- Security Specialist - michaels@lightspeedsystems.com
-- Sys Admin            - schubert@fsck.org

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