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I Hate Computers

My duty to the tech community must be filled, as often I find answers through our lovely friend “Google,” I figure if someone else runs into this kind of a problem they might want to search for a solution, too.


  • Computer connects to wireless network, gets a DHCP lease, cannot access the internet.
  • Cannot even ping local devices, with the exception of the router.
  • Cannot telnet into router.
  • Is able to see other computers on the network in the Finder’s sidebar through Bonjour. Cannot connect to devices.
  • Other computers on local network can see, control, send messages, etc. through Apple Remote Desktop 3.


  • MacBook Pro 15″ Mid 2009 model, 2.53 GHz
  • Connecting to network through Airport.
  • Mac OS X 10.5.7


  • The last time this computer was in the office, it was before we changed the subnet mask from to Also, the DHCP range was changed from 10.0.0.x to 10.0.1.x & 10.0.2.x.
  • The last time this computer was in the office, it was before we swapped a wireless access point from one campus to the other, and having some setup issues with that.
  • When connecting through DHCP, it wasn’t communicating properly, but saw the subnet correctly (252).
  • When setting up through DHCP with manual IP, it saw the old subnet (255), but worked, if given a 10.0.0.x IP address.


  • Connecting through ethernet showed the same results.
  • Removed Airpot from list of network connections.
  • Resetup the DHCP server.
  • Rebooted DHCP server.
  • Tweaked configuration of wireless access points.
  • Removed the following files from /Library/Preferences/SystemConfiguration/
    • NetworkInterfaces.plist
  • Tried booting off of an install DVD, and checking if the problem persisted. It didn’t.
  • Upgraded machine to Mac OS X 10.6.0 (Snow Leopard).
  • Deleting the /etc folder and reinstalling 10.6.

I wanted to avoid reimaging the machine. The profile is a roaming user profile, so all the data is synchronized to the server, but from experience, this user has such a large profile that it takes hours upon hours to synchronize the data on first login to a machine. I figured that upgrading to 10.6 would resolve this. Fortunately, I’ve been running 10.6 on my own laptop for a while now, and haven’t had any problems1. After a lot of suggestions and brainstorming from two wonderful people, Vince and Graham, Vince came up with the idea of trashing the /Library/Preferences/SystemConfiguration/preferences.plist which has a LOT of network data in it, and has since required some reconfiguring the machine. But it worked!

Thanks Vince!

Or so I thought. Then this issue appeared once again, magically, but this time on another computer. I deleted the preferences.plist and it didn’t fix a thing. I then went through everything I had done with the above machine. Still didn’t work. WTF? I wiped the machine, it worked. Then I used Migration Assistant to move the users and applications over. It stopped working. So I wiped the machine again. Moved across the /Users, still worked. Moved across the /Applications, and it stopped working. It stopped working when Parallels tried to create a virtual network port! I deleted the virtual port and it worked!

I’m going to test out VirtualBox and see if that works. Someone in China who uses the same Student Information System as us says it works.

  1. On the work computer []

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