14 Replies Latest reply: Mar 18, 2009 1:58 PM by mgill77
stew04 Level 1 Level 1 (0 points)
Twice in the past few days a message appears on my IMAC G5 running Mac OS X (10.5.4)
"This computer's local hostname Macintosh.local is already in use on this network. The name has been changed to Macintosh-2.local"

My local network consists on one PC and printer and my Mac and printer on either a wireless or cable connected setup. My wife does not print to my printer, nor do I use her's. I use the network to reach our broadband access.

Any idea why this message is appearing? Does this imply that someone else accessing our network? Could a virus on the Mac cause this?



IMAC g5, Mac OS X (10.5.4)
  • Mulder Level 6 Level 6 (8,980 points)
    Does this imply that someone else accessing our network? Could a virus on the Mac cause this?

    No, and No. There are no viruses for Mac OS X, so that could not be the cause.

    More likely is that you've named your computers identically and the first user on the network gets Macintosh (.local), so the next person (you) can't use that, so Mac OS X changes it temporarily to Macintosh-2.local. You can check this and change the names of each machine to something unique such as Borg Cube, Darth Vader, or whatever you like to avoid this problem in the future. To do that, go to System Preferences > Sharing and look at the Computer Name and change it if necessary.

  • William Boyd, Jr. Level 6 Level 6 (10,515 points)
    ** you've named your computers identically **

    That's not the case on my network, but I still see the "local hostname" message regularly.
  • William Boyd, Jr. Level 6 Level 6 (10,515 points)
    I still have this problem after the 10.5.5 update. I have three Macs, all named distinctly. Of the two that are used frequently, one, an Intel iMac, never has this message, The other, a G4 PowerBook, has the message frequently, but not every time it awakens from sleep.
  • William Boyd, Jr. Level 6 Level 6 (10,515 points)
    A correction to a claim in my last post: I saw the "local hostname" message on my iMac today. However, I rarely see it, while I see the message several times a day on my PowerBook.
  • Mulder Level 6 Level 6 (8,980 points)
    If this only happens when you're not physically connected via Ethernet to your cable Internet service, then I would have to surmise that your wireless connection is not secure from outsiders. I can't be sure of that because I never use wireless connections for anything, but you may find the information for securing your wireless network here helpful in determining if an outsider is connecting to your system without your knowledge.

  • William Boyd, Jr. Level 6 Level 6 (10,515 points)
    The two computers that I use most frequently and that encounter this problem are both wired via Ethernet to a Time Capsule, which is connected to my cable modem. The Time Capsule is enabled to service wireless nodes, but since it uses WPA2 security, I doubt that anyone else is penetrating my network.
  • treaty Level 1 Level 1 (0 points)
    I just saw this today for the first time... mac mini server running on my network had it's name changed automatically from "Sumeria.local" to "Sumeria-2.local". I never saw the duplicate name warning mentioned earlier in this thread and I'm positive that this is not due to a security breach on my local network...

    Clearly the mini decided it needed to change it's name on it's own for some reason and did it... but it breaks all the network shares and mapped drives I have set up on the PC's on my network. Why does Apple not have this documented anywhere?

    I have a hunch that it has something to do with Time Machine but I haven't figured it out yet... I never saw this happen until I set up Time Machine backups to this device over the network...
  • baltwo Level 9 Level 9 (62,010 points)
    The only time I've ever seen this is when two machines have the same name entered into System Preferences->Sharing->Computer name. Check all of your machines.
  • ALLizonANikon Level 1 Level 1 (0 points)
    I have one mac computer and I got that message this morning
  • ALLizonANikon Level 1 Level 1 (0 points)
    are you sure there isn't a virus or someone try to hack my machine?
  • ALLizonANikon Level 1 Level 1 (0 points)
    could someone have gotten my IP address from a website I've gone to and is now accessing my computer?
  • Michael Byczkowski Level 1 Level 1 (120 points)
    I had issues with my local hostname when I misconfigured my local server (see http://discussions.apple.com/message.jspa?messageID=8377749#8377749); maybe you've an overlap between either WiFi and Ethernet/DHCP and Fixed IP?

    Best regards,
  • Ian Parkinson Level 6 Level 6 (10,475 points)
    We have the problem on my mothers G5 iMac. Her machine is connected to an ADSL modem via Ethernet. There is no wireless network and no other computers in the house. It cannot in her case be caused by 2 computers having the same name. The message came up right after wake up from sleep.
  • mgill77 Level 1 Level 1 (0 points)
    This, for me, is entirely due to wireless networking. I have a wired Ethernet connection and, when I turn airport on, the local hostname is changed ( presumably due to the new network connection ).

    Turn off the wireless connection if you are able to.