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Message from richardson@rutgersprep.org

Friends,

Yesterday we started experiencing a very strange phenomina we can't track down.

Our laptops which authenticate to wireless through our AD server are showing a popup message that they can't use ip address 5.111.193.4 as it is already in use on our network.  We have never used any "5" address internally.  We have had this happen (as far as we know) on half a dozen MacBooks and one iPad.  The address appears to belong to a telecom in Syria.

We are really not sure what steps to take next.

If anyone has some thoughts, we would be most grateful.

Thanks.
P
Peter K. Richardson
Director of Information Services
Rutgers Preparatory School
1345 Easton Avenue
Somerset, NJ 08873
732-545-5600
www.rutgersprep.org

********** Participation and subscription information for this EDUCAUSE Constituent Group discussion list can be found at http://www.educause.edu/groups/.

Comments

Message from schmelderm@lancastercountryday.org

Peter,

I would encourage you to look at your external firewall and router setup to see if there are any issues there. Has anything changed? 

I had this same issue pop up (not the strange IP address, but an external one) on my network after establishing a DMZ incorrectly and introducing a backdoor loop into my network.

Mike


I saw something like this when a piece of software used to tunnel through firewalls used the same IP address across installations. Removing the software resolved the issue.

Robert


Message from vieird@d-e.org

Are Kids using proxies or some other software to try to get around firewall and internet filtering software

Dave

Message from richardson@rutgersprep.org

Thanks to all for the thoughts.  We are picking away at it.

I will report back what I learn.

Just over a month til we meet in Hightstown.  Tom, are you ready for us?

P
Peter K. Richardson
Director of Information Services
Rutgers Preparatory School
1345 Easton Avenue
Somerset, NJ 08873
732-545-5600
www.rutgersprep.org


Message from tphelan@peddie.org

We're way ahead of you. We've already made plans to double the amount of beer. The rest is just trivial details that I don't pay much attention to.

Tom

Message from richardson@rutgersprep.org

Now I know why everyone thinks so highly of you.

See you in June.

Peter

On Thursday, May 10, 2012, Thomas Phelan wrote:
We're way ahead of you. We've already made plans to double the amount of beer. The rest is just trivial details that I don't pay much attention to.

Tom

Message from richardson@rutgersprep.org

Friends,

We have found the rogue DHCP server.  This is what we discovered.

A user was running Hamachi, a free VPN solution offered by LogMeIn. 

Hamachi uses a DHCP server service with the 5.x.x.x range when creating a private network. 

The system was identified using a combination of dhcploc.exe (found in the Windows XP SP2 Support Tools pack) to probe for DHCP servers and Wireshark to find the MAC address of the responding server. 

The user was then identified through the RADIUS server authentication logs.


Thanks to everyone for your help.


P

Peter K. Richardson
Director of Information Services
Rutgers Preparatory School
1345 Easton Avenue
Somerset, NJ 08873
732-545-5600
www.rutgersprep.org

********** Participation and subscription information for this EDUCAUSE Constituent Group discussion list can be found at http://www.educause.edu/groups/.

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