AAFID (Autonomous Agents for Intrusion Detection) is a distributed monitoring architecture with an orientation towards Intrusion Detection developed at the CERIAS at Purdue University. AAFID2 is a prototype implementation of the architecture that includes several ready-to-work agents, plus development facilities for writing your own.
ACL2 is a mathematical logic, programming language, and mechanical theorem prover based on the applicative subset of Common Lisp. It is an "industrial-strength" version of the NQTHM or Boyer/Moore theorem prover, and has been used for the formal verification of commercial microprocessors, the Java Virtual Machine, interesting algorithms, and so forth.
ADMLogger is a log analyzing engine. Using this core, users could easily build upon it with plugins. With very little Perl programming knowledge, it may become a powerful tool in a System Administrator's toolbox. ADMLogger creates email reports that can be formatted plain text or full HTML, which is up to the plugin designers to support. The main system has an HTML preference, so if your plugin ignores it, so be it. ADMLogger will also remove all filtered entries from the main syslog file into a second file so your other entries are more noticable.
AIDE (Advanced Intrusion Detection Environment) is a file and directory integrity checker. It creates a database from the regular expression rules that it finds from the config file. Once this database is initialized it can be used to verify the integrity of the files. Several message digest algorithms are used. All of the usual file attributes can also be checked for inconsistencies.
AMaViS (A Mail Virus Scanner) scans e-mail attachments for viruses using third-party virus scanners available for UNIX environments. It resides on a UNIX (Linux) machine and looks through the attached files arriving via e-mail, generates reports when a virus is found and sets the delivery on hold.