Preventing Static IP's
Posted on 2009-02-18
I need to find a way to prevent laptops that are using our wireless network from assigning themselves a static IP.
Let me give you a little background on our network:
- We are a high school
- We are using multiple 3Com 4500G Switches
- Our wireless network is a 3Com Managed WX2200 w/ around 45 AP's
- School owned computers have Static IP's - Student laptops have reserved DHCP
- We have a NAC that sits infront of our DHCP server to enforce policies before a laptop or outside computer can gain access to the network.
- We are using a 10.x.x.x Class A IP scheme. No VLANs or routers.
What we are finding is that students are becoming wise enough to figure out how to get around the NAC enforced policies by putting a static IP on their computer prior to making a wireless connection. Because the NAC sits in line with the DHCP server, if the NIC never requests a DHCP, it never gets challenged by the NAC.
I need to know if there is a way to keep users from being able to put a static IP on their computer and gain access to the network. Is there a way that I could use the switches, by where I provide it a list of MAC addresses that should be requesting DHCP and if they dont, block them???
Any and all solutions are welcomed :) Thanks in advance!