Assign 2 MACs the same IP address?

  • I have a few devices that get moved around time to time that have both Wired & Wireless adapters on them.  Sometimes they are on Wireless in one location but Wired in another. In the past, I setup DHCP Static leases for several of them to have the same IP on regardless of their interface.  I have several devices like this that I know won't have both adapters on at the same time (IP Cameras, Xbox One, AppleTV, etc).

    I just tried to configure it today (I haven't tried setting it like that in awhile) and it no longer works (saying correctly that that IP/MAC/Etc is already in use. I still have several in there still setup like that, so I know it did work at one time. Is there a way to bypass this safety check? Obviously you wouldn't want this in most cases, but it's handy in this one. (I have several firewall rules for many of these devices and have found that people would switch to the other adapter to bypass the rules. :)

    Any suggestions appreciated.

  • Banned


  • LAYER 8 Global Moderator

    Put your wireless on its own segment, this allows you to create rules for wired IPs and wireless IPs and not have to worry about a device getting the same IP with different mac's

    You set reservation so wired gets 192.168.1.x/24 and wireless gets 192.168.2.x/24, simple/sane/easy!

    If need to be on the same broadcast domain, then just use 192.168.1.x/24 as wired 192.168.1.x+1/24 for wireless.  If need be change to /23 or /? to allow for the IPs need for 2 different IPs per device and adjust your rules to account for what your doing.. Maybe vs +1 for wireless put your wired 1st half of address space and wireless in 2nd half, etc.

    So if you using, 192.168.0.x = wired and 192.168.1.x = wireless.

    Setting up dhcp reservations that could assign same IP to different macs is just broken and not how you should address the problem.

  • If you can make sure that your devices have only one of their interfaces active at a time you could clone on them directly the mac addess of one of the interfaces.
    –> Both interfaces have the same MAC.
    (A really bad idea if you don't know what you are doing)

  • LAYER 8 Global Moderator

    ^ I would say that is a really bad idea even when you know what your doing ;)

    But sure that is another way to skin the cat..

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