Due to the frequency of people asking here about obsolete JForum versions I though I'd take a moment to write down the current state of that project
Though the home page of JForum looks to be http://jforum.net/, that site is actually obsolete. It had been maintained by the original author of JForum, Rafael Steil. He and his team maintained JForum up to version 2.1.9, the latest one available from that site. That version is now obsolete, as it has not been worked on for many years, and has numerous published security holes. Its source code is also available at https://github.com/rafaelsteil/jforum2. Update: jforum.net now redirects to SourceForge; that should ensure that people no longer download the obsolete version.
At some point Rafael worked on an improved JForum 3, but that effort never resulted in a usable forum software, and has been abandoned as well. What code there is can be found at https://github.com/rafaelsteil/jforum3.