I ran into the most annoying thing I have experienced on a Mac. This past Saturday night my iMac would not connect to the router. I had been connected an hour earlier, but for some reason it would not connect. I was getting a “connection timeout” message.
So began my troubleshooting of the problem. First I assumed there may be something wrong with the router. I unplugged both the power and phone line, but still the connection timed out. To double check I fired up the MacBook, which connected without issue.
Perplexed, I went to the utilities folder and opened up Keychain and deleted all the networks. This proved to make things worse as now my airport could not find a single network. This then turned me to search the Internet to find a solution. In doing so I found this post on the Apple discussions board. There were many ideas, but this one made progress.
Has anyone tried this fix. I don’t have access to my MBP right now to try myself.
1. Go to Finder > Macintosh HD > Library > Preferences
2. Pull SystemConfiguration folder onto the desktop
4. Go System Preferences > Network
5. Select “New Location” under the Location drop down menu and give it a name
6. Select “Airport” under the show drop down menu
7. Go to By default, join: and you can leave it on automatic or with preferred networks and select or add your network
8. Click “Apply Now” and all should hopefully be golden
9. If all is good, trash the folder on your desktop
After following the instructions and opening my connection I was able to connect on the iMac. So I thought success. However, I could not leave the Internet connection open due to security issues. I switched back to WPA, but it resulted in a lost connection. After an hour of frustration, I found this article. Moreover, I found the root of my problem.
I finally decided to take a look at the Mac firewall logs. You’d think that would be the first place I’d look, being a security guy. They’re kind of hidden in plain sight, a few layers deep in the Mac’s preferences dialogs. You go to the System Preferences panel, in the Security section, then the Firewall tab, then click the Advanced button, and finally click the Open Log button. If logging isn’t already turned on, you can enable it there, as well.
Sure enough, I looked in the log and found several examples of this (emphasis mine):
Feb 8 23:02:04 greg-hughess-macbook-air Firewall: Deny configd data in from 192.168.0.1:67 uid = 0 proto=17
Feb 8 23:02:26: — last message repeated 2 times —
Ah hah… Apparently the firewall was refusing inbound connections initiated by the router as it tried to set up the DHCP address being requested by the laptop.
In followed the instructions, but still no success. Then it came to me, if it is the firewall and some how the com.apple.alf.plist file had become messed up, why not use Time Machine and revert back to when the file was working. SUCCESS!!!!!!!
After restoring a previous version of the com.apple.alf.plist file I was able to connect. I have no clue what I did to cause the firewall problem, but it appears the issue was a result of the Leopard firewall blocking some kind of handshake between my Airport and the Router verifying the WPA key. Thank goodness for Time Machine.