I'm looking for a way to grant new (remote, public) users the possibility to sign up for a new account via a web form, which will grant access to a restricted area of our website, an SVN repository, a Trac system, and a MediaWiki (all hosted on a Linux server).
Currently a new Linux system user account is manually created for each new user, though I realise this isn't ideal from a security (or management/administration) point of view, hence this post.
Can anyone suggest any ways in which this might be done (I realise this is a high-level request. I'm looking for overviews of possible solutions that I can look into, rather than detailed solutions).
We have a PHP list and SQL database in place and if that helps...