OpenACS can ban users, but not IP-addresses. The only way to stop vandals is to require user approval before they can join which is a bit against the Wiki idea.
Good point. By looking the the increasing number of spam content on openacs.org, it looks like a good idea to ban sites (i.e. not allowing a login from banned IP-addresses or subnets) as well. The same mechanism could be used for all user-contributed content, i.e. wiki-pages, forum posts, comments on pages, oacs company listings, etc...
