Everybody thinks that running a virus scanner on a Windows box is a good thing, right?
Well, it seems that it can be bad if you want to have working IPv6.
I spent several hours at a customers site yesterday working on IPv6 enabling their Windows XP workstations, but was having issues. I did the usual trick of turning off any and all Windows firewalls and the virus scanner, but we still had issues.
The behaviour was that IPv6 addresses were being allocated, we could ping and tracert6 to IPv6 hosts, we could telnet to port 80 on them, but neither Internet Explorer or Firefox wanted to work. Going to an IPv6 website would cause the browser to just hang. Looking in a network dump I could see an initial connection being made to the server, but then no actual requests.
I decided to blame the virus scanner, on the basis that they quite often interfere with the normal flow of events. Even though it was turned off, it might still be interfering. After actually uninstalling it (and rebooting, uninstalling it caused Internet Explorer to crash), everything worked!
Moral of the story, if you're using a virus scanner (in this case
NOD32 from ESET) and you're having issues using IPv6, uninstall the virus scanner!
