Ethernet ID Questions

Discussion in 'MacBook Pro' started by Dangerdom, May 31, 2007.

  1. Dangerdom macrumors newbie

    Joined:
    May 31, 2007
    #1
    Is there anyway that I can change the assigned ethernet ID on my Mac?

    17" MacBook Pro OS 10.4 2.16 GHz Intel

    I have tried the following

    sudo ifconfig en0 lladdr 00:01:02:03:04:05

    In the terminal, with different numbers of course. And then when I try the following:

    ifconfig en0

    It tells me that it has changed the ID, However, in System Preferences > Network > Built-In Ethernet > Ethernet it says that it has not changed and still displays the old ID. Any ideas?
     
  2. yellow Moderator emeritus

    yellow

    Joined:
    Oct 21, 2003
    Location:
    Portland, OR
    #2
    My guess is that the Network prefpane pulls it directly from the network interface in question, not from the network stack, which is where I believe you're changing what you're changing.

    You do know that changing your MAC like this won't survive a reboot, right?
     
  3. Dangerdom thread starter macrumors newbie

    Joined:
    May 31, 2007
    #3
    Thanks for the help yellow. Is there anyway I can change where the Network prefpane pulls it from?

    I do know that it won't survive a reboot. I read somewhere that I can add it to my .cshrc file or .profile , but I am not quite sure what that means. I am pretty new to this level of stuff.
     
  4. yellow Moderator emeritus

    yellow

    Joined:
    Oct 21, 2003
    Location:
    Portland, OR
    #4
    It's hardcoded, so you really cannot change it.
    Your best bet is to buy a router (which has a mutable MAC address) and use that as a bridge between you and whatever you're trying to do/hide from.

    Frankly, I'm not even sure changing it via ifconfig actually changes how the (real) router to the outside world sees it.
     
  5. Dangerdom thread starter macrumors newbie

    Joined:
    May 31, 2007
    #5
    thanks for the info.
     
  6. yellow Moderator emeritus

    yellow

    Joined:
    Oct 21, 2003
    Location:
    Portland, OR
    #6
    The way to test if changing it via ifconfig is actually enabled and not just '/dev/null'ing for looks is to use an app like ethereal to sniff the network from another computer. See what the MAC address is from and untouched Mac and then from the touched Mac. See if they are different.
     
  7. diadem macrumors regular

    Joined:
    Nov 13, 2006
    Location:
    Glasgow
    #7
    Changing the Mac in this way will change the Address broadcast to the ARP table, The reason they are hard coded is to stop duplicate MACs. It prevents issues when there are 2 MACs the same in an ARP Table.
    If it were to happen you would end up with 2 computer trying to share an IP address.

    I would not sugest doing this unless on a private LAN. As the example you gave would more than likly create a problem, As the cheaper LAN cards out there dont tend to reg them self with the governing body to get there ID for the MAC address's on there card.

    Prob more than you wanted to know but meh..

    yellow he aint using a network router or switch from the sounds of things :)
     
  8. yellow Moderator emeritus

    yellow

    Joined:
    Oct 21, 2003
    Location:
    Portland, OR
    #8
    Nope.. but I had to ask. :)
     
  9. evvywolfe macrumors newbie

    Joined:
    Oct 1, 2009
    #9
    I cannot connect to the ethernet since a few days ago [nothing happened, it just randomly stopped connecting] but I can connect to airport still so I get internet and can print and stuff.

    When I checked the ethernet connection of the main computer it has a different ethernet id to my computer. Do the ids have to match for me to be able to connect?

    P.s. I have Mac OS X 10.5.7
     

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