Version 1

circa 1996 - 1999.
known as 'smt' (system monitoring thing)
collection of perl and shell scripts. Ping and limited SNMP capabilities. Notifications via coded numeric paging.

Version 2

circa 2000 - 2001.
known as 'whassup' (variation on "what's up").
complete rewrite
Extensive TCP, UDP, and program testing capabilities. Notifications via text pages (via qpage). Web front-end.

Version 3

circa 2001 - current
known as 'argus' (from Greek Mythology).
complete rewrite
more efficient engine, more generalized monitoring, notification, and escalation systems.

Version 3.1

circa 21/Oct/2002
added per user views, and access-control

Version 3.1.1

circa 1/Nov/2002
Bug fix release.

Version 3.1.2

circa 8/Nov/2002
Bug fix release.

Version 3.1.3

circa 2/Dec/2002
Bug fix release.

Version 3.2

circa 14/Apr/2003
added many new features: graphing, IPv6, additional tests, extended testing capabilities, user configurable notification methods, etc.

Version 3.2.1

circa 15/Jul/2003
Bug fix release.