Snort is a free open source network intrusion detection system (IDS) and intrusion prevention system (IPS) created in 1998 by Martin Roesch, founder and former CTO of Sourcefire. Snort is now developed by Cisco, which purchased Sourcefire in 2013.

In 2009, Snort entered InfoWorld‘s Open Source Hall of Fame as one of the “greatest [pieces of] open source software of all time”.

https://en.m.wikipedia.org/wiki/Snort_(software)