MAC ADDRESSES - CAN THERE BE DUPLICATES

 luanncross,

Just thinking. Some newer models have Internet Protocol Version 6 (TCP/IPv6) and Internet Protocol Version 4 (TCP/IPv4)

 I have both of mine set for DHCP

One of these may be set for DHCP and is what you're seeing.

There are tools out there to change your Mac Address. People use them to clone change their computer to a Mac Address of another computer on the network, so they can get online, hacking tools.

It might be possible to get another adapter with the same Mac Address. Considering how many computers are out there, the have to eventually run out of mac addresses and start over.

If your network is wired, then there are no problems with the wired computers. For the laptops, not knowing if you have other wireless devices attached to your netwpork, like printers, cell phones, etc..., tightening up the security would be the direction to take. If people use their Cells, then I would suggest using these Recommended Wireless Router Settings, I use channel 11. The cells might not be able to connect to a hidden network, my daughter cannot. You can then use the Mac Address filtering as well and the network should be secure. If you then see this issue, then it has to be the computer(s) in question.

Rick 

Thanks for that.  No, these PC's don't have the IPV6.  We disable those anyway on the newer ones.  The only hidden devices under the Network Adapters are -

• Direct Parallel
• WAN MINI Ports

We have managed to identify and block unauthorised access on the DHCP as you suggested, through the wireless access points etc.  There are just, now 3  MAC addresses that continue to appear and grab DHCP addresses and the identified MAC addresses match those MAC addresses of the Dell PC's LAN Network Adapter.  Continues to puzzle us.

 luanncross,

Cell phones, USB wireless adapters, iPods, computers and printers all have mac addresses. I'm guessing that you're some type of business and really trying to keep the security tight, correct. Depending on the operating system of these computers, since these are you computers, you could change the mac address to something you can manage. The tools out there that work. I changed the Mac address on one a while back to see if it could be done. I no longer have that computer.

Rick

Just to post this again - We now have 2 Dell PC's that are renewing DHCP addresses.  Dell Optiplex 330 and Dell Optiplex 755.  I have disabled as many hidden Network devices that we don't use from both of these PC's.  But the MAC address that continues to gain a DHCP address is the one on the Intel 825666DM-2 Gigabit Network Card on the 755 and the Broadcom NetXtreme 57xx Gigabit Card on the 330?  Again, both these cards have fixed IP addresses.

It is not necesarily a problem, but I don't like rouge things taking up the few DHCP addresses we currently have.

Just wondered if anyone had any more thoughts?

You have to disable the intel me amt in system setup on boot. Hit F12 and goto the intel option, enter admin as password and change the password to a good strong one with special characters and number ect.. then goto the top option and disable the intel option. this fixed my problem.