Discus from http://www.discusware.com is a message board written in Perl.
One of the advantage of the script is it store threads in HTML page, no MySQL or other type of database is required. Having each thread available in HTML page will allow Search Engines to index the page, also reduce server load as there is no processing is required to view the pages.
Installation of Discus can be done with FTP or through command prompt (SSH). Discuss will generate packages that is specially build for your site, with paths set in the perl script, so installing is easy, just follow the instructions, your forum will be up and running.
You can see discuss professional installation at