Xtradius is a radius server that permits you to handle user authentication and accounting request via external scripts. You can handle script requests for user accounting, user authentication, NAS start and NAS stop packets. You can also write additional information into the NAS detail logfile. Parameters to scripts are passed via command line options or environment variables, making it very simple to implement SQL-based user accounting, authentication and account expiration. It is also compatible with "standard" cistron radius server.
MailScanner is an email virus scanner, vulnerability protector, and spam tagger. It supports the Postfix, Sendmail, Exim, Qmail, and ZMailer MTAs, and the Sophos, McAfee, F-Prot, F-Secure, CommandAV, InoculateIT, Inoculan, eTrust, Kaspersky, Nod32, AntiVir, BitDefender, RAV, Panda, DrWeb, ClamAV, and other anti-virus scanners. It uses SpamAssassin for highly successful spam identification, and is designed to handle denial of service attacks. It will detect password-protected zip files and apply filename checking to their contents. It is very easy to install, requires no changes at all to your sendmail.cf file, is designed to be lightweight, and won't grind your mail system to a halt with its load. It can be integrated into any email system, regardless of the software in use.
bdmn is client/server-oriented backup system. The daemon runs on the machine being backed up, and the client runs on the machine that stores the backup. It is very simple, but very fast. It only uses tar, gzip, uuencode, and Perl, so it is portable to many operating systems. It includes a very simple access control system for itself.