Nikto is an Open Source (GPL) web server scanner which performs comprehensive
tests against web servers for multiple items, including over 3500 potentially
dangerous files/CGIs, versions on over 900 servers, and version specific
problems on over 250 servers. Scan items and plugins are frequently updated and
can be automatically updated (if desired).

Nikto requires libwhisker2 and Net-SSLeay perl modules, both of which are 
available in the SlackBuilds.org repository.