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DHCP Bad Addresses

Posted on 2006-05-22
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Last Modified: 2013-11-13
I have a Windows 2003 DHCP server on my network. It is coming up with “bad addresses” that are using up my entire scope. The unique IDs tied to the bad addresses, which are usually a MAC address, is in the range of 3301a5c0 ~ 8501a5c0.

Can anyone help me figure out why this is happening? This is my only DHCP server.
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Question by:tmtroutman
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gfrair earned 180 total points
ID: 16735114
Is there any possibility that another DHCP server is running on the network.  Possibly a new router, Linux box, etc.

Just a thought.
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by:2266180
2266180 earned 320 total points
ID: 16735188
maybe there was a mac spoofing tentative on your network? don't you have some logs from the period this started to happen? maybe you could trace the problem from there.
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by:2266180
2266180 earned 320 total points
ID: 16735204
was thinking of something else: replace "mac spoofing" with "network poisoning" or somethinglike that. it involves sending some large amounts of fake info mostly bad MAC's and invalid routes.
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Author Comment

by:tmtroutman
ID: 16735355
I have narrowed it down to my new dell PowerConnect 5324 switch. However, I'm not sure what settings to change to prevent this from happening. The switch is not acting like a DHCP server.
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Author Comment

by:tmtroutman
ID: 16735986
My switch had a vlan setup on it. I disable the dhcp interface to this and all is well. Thanks to everyone for your help!
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