RE: Rogue IP Address

["Jose Guevarra" <jose () iquest ucsb edu>]

  I think we can narrow down solutions by understanding what type of
equipment is being used here. nobody seems to know anything about Asante
switches. 

 Andy, could you give us some specs on it, capabilities and such. You said
that the port to IP feature wasn't working? well that's a very high level
capability that you paid for when buying the switch, it should work.  Why
isn't it working now?
I would also suggest doing a fast ping scan of you subnets and grabbing MAC
addresses from you arp tables. then start narrowing down who they belong to.
Are you using DHCP reservations?  

hth




-----Original Message-----
From: Alaric Darconville [mailto:alaric () cowboy net] 
Sent: Friday, May 02, 2003 12:08 PM
To: security-basics () securityfocus com
Subject: Re: Rogue IP Address


I have seen a few responses to this stating to block that IP address at the
router, or to reassign that address to another machine, in the hopes that
someone will holler about his network not working.  But someone
intentionally using an IP address different from what they were assigned is
probably not going to turn himself in like that.  It would be akin to
driving a stolen police car to the city garage and having the engine looked
at.  

It might be as simple as someone mis-entering the IP when setting up the
system, but if it's a Linux machine then it's probably not doing the same
things the user's ordinary workstation would be doing, 
therefore, he'd have to leave that machine running.  On the other hand, he
may have a dual-boot configuration on his machine, in which case, the IP
he's usually assigned won't always show up on the network (disappearing when
he reboots to go to his Linux setup).  Perhaps the IP he's using is some
sort of accidental transposition of characters (171 instead of 117, for
example.)  But if no IP's dropped off the face of the earth when the new one
started showing up, it's definitely "IP theft."  He's not going to call tech
support, he'll just switch to another stolen IP.  For the most part, you're
going to ahve to assume that he knows what he is doing is wrong.  Forget
trying to get him to call when that machine can't connect.

Looking for extra machines in the area may help track it down.  Pinging it
to get the MAC address from the Arp cache will identify the machine a bit
further.  Trying to telnet to standard ports (25, 110, 23, etc) may reveal
banners to help identify it.  Maybe you'll be lucky and the sendmail banner
displays "220 masterofpuppets ESMTP Sendmail 8.11.5" etc.... Look for the
huge Metallica fan in the building :)

Alaric Darconville


Andy (dondon () pacbell net) wrote:
> Someone on our network assigned an IP address to their own system 
> without my knowledge.  Using LANguard network scanner, the best I can 
> tell is that it's a Linux box.  The port-to-IP mapping table on our 
> Asante switch doesn't see to work correctly.
>
> Any suggestions on tracing down that system that is associated with the 
> IP is appreciated!

Andy



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FastTrain has your solution for a great CISSP Boot Camp. The industry's most
recognized corporate security certification track, provides a comprehensive
prospectus based upon the core principle concepts of security. This ALL INCLUSIVE curriculum utilizes lectures, case 
studies and true hands-on utilization
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to win one of the latest technological innovations, the SEGWAY HT.
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