I know this has probably been discussed to death by the core developers but I came across this discussion at another forum. And to be honest I don't know enough of PHP to say whether this is a possible solution or not. But who am I to say? I rather post the lead here than miss a possible solution.

So for what it is worth I hope the core developers have a read of the last few post by user Zaher in the thread listed below and maybe it could be of use.

http://forums.punbb.org/viewtopic.php?id=4385

Like I said, I don't know if I am barking up the wrong tree but it sound like the guy had an idea.

And just for your info - yeah I had people who couldn't login because of firewalls. And you can see the glazed look on their face when you try explaining to them they need to change their firewall settings. My target audience are not net-savvy users.