Most companies that choose not to run an IDS do so because of the cost. Thankfully there is Snort. Snort is sometimes referred to the poor man's IDS but that is misleading. Snort is an open source yet powerful software used by many corporations and government sector organizations. Snort was developed for use in Linux systems but has been ported for use in numerous platforms including Windows, Solaris/SunOS, BSD Unix, and Mac OS X to name a few.
Snort has three main modes it operates in: NIDS, Packet Sniffer, and Packet logger. It has other modes as well (In-line, Real time, or Schedule checks) but these are the main three. In NIDS, Snort works to detect potential network intrusions using a rule-based intrusion-detection mechanism. Packet Sniffer enables it to display all network traffic to the user and provides flexibility to display entire packets or certain header information; this is great...
