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Self-Assigned IP - Tried Everything?

After Googling for hours and trying everything found on these forums and others, I am at a loss of what to try next.

The Self-Assigned IP address error will not go away on my Macbook. I recently upgraded from 10.5.8 (Leopard) to 10.6.2 (Snow Leopard).

What I have tried...

1) Deleting all network related Preference files:
/Library/Preferences/SystemConfiguration/com.apple.airport.preferences.plist
/Library/Preferences/SystemConfiguration/NetworkInterfaces.plist
/Library/Preferences/SystemConfiguration/perferences.plist
/Library/Preferences/SystemConfiguration/com.network.identification.plist

2) Disabling Firewall (it was never on, tried on/off multiple times)

3) In Keychain Access. Locating network in question. Access Control. "Allow all applications..."

4) Deleted All Network Locations. All network connections. All network passwords. Retried 1-3, no luck.

5) I can plug directly into wireless router and receive an IP address on the Ethernet.

6) I cannot manually assign an IP address (IP, Router, DNS, etc.).

Other notes of interest...

1) This occurs on multiple networks, but not all.
2) My iPod Touch connects successfully to all networks where my MacBook self-assigns. Other PC computers connect successfully to the network also.
3) I never had an issue with self-assigned IP addresses before upgrading to Snow Leopard.
4) After upgrading to Snow Leopard, I had other issues (the freeze issue in particular) that I resolved by creating a new user account.

Replacing the router is not an option (it is not mine). Re-installing Snow Leopard is not an option.

Any other ideas floating around I have not listed/tried above? Thanks for the help!

MacBook5,1 - 2.4 GHz - 4GB, Mac OS X (10.6.2)

Posted on Feb 17, 2010 10:31 AM

20 replies

Feb 18, 2010 3:48 PM in response to Brendon McCarthy

My 2 cents...
Do you have any MAC filter (security) on your router which may prevent IP assignment???

MS

coldone

Level 1

30 points

Feb 18, 2010 9:44 PM in response to Mauro Straulino

Morning,

hmmm, really strange... Apart from an forgotten firewall setting, there is nothing that comes to my mind at the moment, that could cause such a behaviour.
Have you had (or still have) installed some kind of firewall (or security suite) that does package filtering, causing a drop of DHCP responses?

C.

Mar 21, 2010 12:20 AM in response to coldone

Here is what worked for me:

I have had this problem several times, the latest after migrating my system to a new computer. I tried all the standard techniques described in this and other threads to no avail. This is the solution that has worked for me each time this comes up:

Go to the terminal window.

Paste in: sudo ipfw -f flush
Enter password

(This flushes all firewall rules)

Then turn Airport off and then back on.

In my case, after turning Airport back on, it made the connection without further problems.

Interestingly, I had to do this even though I had the Firewall turned off completely. I can't say I understand why this worked but it has for me several times, so I hope it will be useful to someone else who has this incredibly frustrating situation.

jbrejcha

Level 1

0 points

Mar 27, 2010 2:05 AM in response to Brendon McCarthy

Try resetting the firmware by hoding cmd-opt-O-F during restart, then type
0 > reset-nvram
Press Return
0 > reset-all
Press Return

This solved the issue on my iBook.

Apr 10, 2010 8:55 PM in response to Brendon McCarthy

I have had similar symptoms with one of my macs (Mac Mini) in the last month or so (it would do a combination of self-assigned ip address, no ip address and occasionally not even connecting to the airport). I had tried all of the methods mentioned on this thread and others too mentioned elsewhere.

I eventually found that the culprit was an HDMI cable (I've got a mini display to HDMI adaptor and HDMI cable going to the TV). I don't know exactly why it interferes, just know that when the HDMI cable is too close it seems to result in these (and if it is a bit further away a really slow connection). Unplugging the HDMI (and using an alternate video out) fixed all.

Have no idea if this is going to help you but thought it was worth putting something else out there - maybe just to double check that there is no interference nearby your laptop.

Self-Assigned IP - Tried Everything?