August 28th, 2009, 09:40 AM #1
DHCP Server interrupted and spoofed
I have been setting up Mac OS X Server as the DHCP server at our school, and at first it was working very well. But an issue we had been having prior to setting up the static maps and when we used an older server resurfaced.
We have assigned every computer on campus a specific IP address based on their MAC ID's, but sometimes, the computers are sent a fake address. Every router we are using is an Airport router, and we have set all the static IP's to be 10.0.25.xxx. We also have a visitor setup with a different set of generic ID's which are handed out. The fake addresses that are sent are of the variety 192.168.xxx.xxx, which I recognize as the standard addresses handed out by Linksys/D-Link/etc. routers which I have had at home.
When I look at the DHCP server log, every normal computer/iPhone/etc. that shows up on the network makes a DHCP Request and is sent an ACK. For the computers and printers which are being spoofed, I see the server Discovering them, an Offer is sent, and then the actual address doesn't get assigned.
On my MacBook Pro, when this happens, I can just renew the lease and the correct one shows up. But on printers which are getting spoofed, I cannot get them to make a valid DHCP request, i keep getting these fake addresses.
Is this problem one which you have encountered, and would you have any possible solutions? I have scoured the network for someone who has brought in another router or is using a switch we didn't know about, to no avail.
I appreciate the help.