Wednesday, March 11, 2009

VPN Blocking port 80 (not Flex related)

This post has nothing to do with Flex, but caused me to waste many hours yesterday so I thought I'd post it in case it helps someone else.

I recently uninstalled Cisco VPN (on my Windows XP machine), and after rebooting I could no longer use port 80. At first I thought I couldn't access the internet at all. Then I realized that I had an IP address, and I could ping google. Then I realized I could still FTP (port 21 and 22), and then I tried accessing a website that uses port 8080 and it worked. So I realized my problem was that port 80 was being blocked. After a little searching I came across this blog that helped solve me problem:

The gist of it is that if VPN isn't properly uninstalled then it leaves behind a firewall that blocks port 80. I have no clue why mine wasn't uninstalled properly. Anyways, if for some reason the link to the blog above doesn't work, here are the steps:
  1. Restart the Windows XP PC in Safe Mode (press some combination of Shift, F5, F8 when booting up your computer)
  2. Run Regedit.exe to open the registry editor
  3. Navigate to HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\vsdatant
  4. Select start in the right pane and modify the value to 3 (mine was set to 2)
  5. Restart the PC and port 80 should no longer be blocked and you can use http with any browser

Amazing that so many hours could be wasted and all it took was changing a 2 to a 3 in the registry!

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