IDS stands for Intrusion Detection System, and is a piece of software used to monitor a network for attempted security breaches. Basically, an IDS is a network sniffer with pattern matching and database of suspicious network activity patterns. These patterns, called fingerprints by some over-zealous marketing departments, can be as simple as an HTTP request for a know vulnerable CGI, or as complex as detecting a 'stealth' port scan.

Some IDS systems can also be used to monitor a network for employee 'misuse' (like visiting Everything at work).

IDS Packages:

Dragon IDS