How can I make a lan based forum?

if you make all the html files, on a shared drive, then it would only be lan based. IE place the files in a folder called "fourm" and set the machine to share it. then when they want to access the fourm, in the address bar for IE they would put something like \\machinename\fourm\imdex.html This way it's only LAN based, and not on the web.

Pretty much any groupware app will have this functionality built in. Take your pick - Exchange, Domino, Groupwise, etc. I don't understand how you think a web service is going to help you when one of the requirements is that it be based on your LAN.

You can run a web server in your local area network without problems, the only difference is that it runs on a local computer and can't be accessed from outside the LAN (from beyond the firewall) unless you want it. Running a local web server is easy, you just need a computer that runs all the time. You can download a pre configured web server framework (LAMP for Linux/Mac, MAMP for Mac, or WAMP for Windows) and run any free forum software (they are mostly PHP and MySQL-based). Users can access the server via web browser and the local IP-address. They can sign up in the forum, just like on any other Internet forum. The forum software contains admin and user management modules. See for example PHPBB: http://en.wikipedia.org/wiki/PhpBB These web server frameworks contain the Apache web server with PHP (including additional modules) and MySQL. Although they are not meant to work as live web servers (more as personal web development systems) they can be set up secure enough for use within a trusted LAN. http://en.wikipedia.org/wiki/List_of_AMP_packages Of course configuring your own server and forum software is a completely different game than using a free web service. Despite the free availability of the software, it will probably require some effort and time to really get on top of it.