The problem with IP bans is of course their tendency to lock out innocent posters with the same ISP... or in some cases, even innocent posters using the same computer as the guilty. For my purposes, I prefer to have IP bans only block registrations, and not block people from viewing/posting -- if I didn't want someone posting, I'd have banned their username in the normal way already. By having it only block registrations I merely lose a few potential new people who could've otherwise registered, but don't have the more serious problem of locking out valued existing posters and making them think they've done something bad.

This can be done with a couple very minor file edits:

Open includes/functions.php and find

function verify_ip_ban()

Replace with function verify_ip_ban($registering = 'no')

Then find global $vboptions, $session;
and replace with global $vboptions, $session;
if ($registering == 'no') return false;

Open register.php and find if (empty($_REQUEST['do']) AND empty($_REQUEST['a']))

Replace it with verify_ip_ban('yes');
if (empty($_REQUEST['do']) AND empty($_REQUEST['a']))

I've IP banned myself to test this. It let me post, but when I logged out and tried to register a new account it told me my IP was banned. Works in 3.00 RC 3, presumably there wouldn't be any changes to these lines in 3.00 final.