I have a phpbb forum where everyday one or two fake users are registering with personal pages like: free p**n , mortgages etc. Any idea how to avoid this ?
You could disable the homepage field, you could make it so that admin approval is required, or you can use an addon to make it so users cannot enter a personal homepage until they have x amount of posts.
Look for a phpbb mod called 'toolkit'. It will allow better user control like deleting all members who are not activated.
Actually there is something you can do with phpBB forums to prevent spam submissions (well most of them anyway) I can't remember off hand how it is done, but it was something to do with editing one of the submission form php files, which would prevent auto submissions somehow. Do a search on google for "prevent phpbb registration spam" or something similar, and I'm sure you'll find what I'm on about. After implementing the hack, I virtually stopped spam submissions completely, apart from very few which still manually submitted.
I think what you are referring to is CAPCHA. Thats visual confimation code on registration form, that will prevent automatic scripts to send registration requests.
No it was something more then just visual confirmation. Auto submitters can still get around that. It was something to do with editing a variable name or something, I seriously cant remember right now...
Do a google search on "captcha pure mango".. I installed his a few months ago. Havent had a single Bot registration since... You can check it out here: http://wiiforumet.se/profile.php?mode=register