Article Date:10th January 2002 Author(s): Clinton "SileNceR" Warburton, Jarrod "sKuLLsHoT" Mast Our Rating: 9/10

DHCP & Conclusion

The result of it all from the DHCP servers point of view:

Interesting facts and conclusion...

We tried setting two of our cards (Intel Pro 100 and the RTL8139) to the same MAC address and the results were quite amusing to say the least :)

Both accepted the DHCP IP binding for the same MAC address, no error messages came up even though we had the same IP Address and MAC address, transferring data on the other hand was quite a failure, upon trying to transfer, Windows 2000 quietly died in the proverbial arse (you had better appreciate that word, it took some serious thinking for two peeps to remember!). After hacking our MACs back to normal, we were able to resume normal operations.

We also found that if you used certain MAC addresses with a given NIC, that they would fail the NIC when attempting to start the device again. We also found that some MACs will start alright on the NIC but will have issues on the network.

Also worthy of some note is the fact that in all Windows based operating systems the new MAC addresses created new "physical" hardware devices as far as software was concerned, meaning that for each time the MAC address was changed we moved to (in XP) Local Area Connection (n+1) so for my original MAC I was Local Area Connection 1 and then 2 for the second and so on, however when I had finished my NIC decided to revert to LAC 1, and the other connections REMAINED. This COULD cause conflicts or driver issues so if after modifying your MAC address you recieve crashes and other errors from network based applications check this first. My main complaint is that in the bandwidth monitor on the WinXP task manager the LAC's are listed in decending order, so I see the unused connections - 3 and 2 - and have to scroll down to see the wanted connection - that of LAC 1.

The content of this guide is in no way intended for purposes malicious, it is provided purely with intent to show those out there who doubt that although MAC's are hardware based they CAN be changed on a software level. Any malicious use of the content of this guide is of the fault of the offender, Not in any way the authors - Clinton Warburton and Jarrod Mast, or in any way OCmelbourne.com and the OCmelbourne staff.