POssible competitor, but moreover just russian and chinese spambots. They (Vbulletin and others) have block lists that keep all those nasty arse bots clean off the server. I use something called .htaccess lists in my webservers directories.
Not to get totally technical, but it's like a bouncer at the door - If you are on that list (IP address range), you simply get ignored - the webserver simply ignores you. Can't even get to the registration, or anything else for that matter.
Vbulletin has a good banning system and allows banning by IP address ranges, but boys there are
hundreds of ip lists in Asia and Russia that are used for nefarious reasons. I used to spend a lot of time keeping up the lists, and then I went the .htaccess route and it's pretty much ended the threat on my sites.
My Dad's website got 30K signups in a week because some yahoo at Wordpress told him to re-install and one of the defaults was "any one can register". He was operating a Christian website at the time, and they just tore that site apart to the point it started affecting the other sites I had on that dedicated server.
The rack server I lease (from a hosting company) uses Linux as an Operating System, and hence it has an apache webserver (the default for Nix systems). Apache webserver uses .htaccess as a method for allow/deny access.
Here is the site for those blocklists if any one is interested;
http://www.wizcrafts.net/chinese-blocklist.html Another handy-dandy tool is:
http://www.ip-address.org/lookup/ip-locator.php With the site link above you can take the IP address from the whos's online or registrant entry and find where they are originating from - down to the nearest internet router - Generally its not possible to get to an exact address/place (RcRed's posting from Mobile home on Copperhead road), but this will get you to their neighborhood..