Description:

Snort is a libpcap-based packet sniffer/logger which can be used as a
lightweight network intrusion detection system. It features rules based logging
and can perform protocol analysis, content searching/matching and can be used
to detect a variety of attacks and probes, such as buffer overflows, stealth
port scans, CGI attacks, SMB probes, OS fingerprinting attempts, and much more.
Snort has a real-time alerting capabilty, with alerts being sent to syslog, a
separate "alert" file, or as a WinPopup message via Samba's smbclient

Snort compiled with snmp+flexresp support. FlexResp allows snort to actively
close offending connections. The snortSnmpPlugin enables snort to send snmp
alerts to network managemement systems (NMS). The alerts can be traps (the
alert will not be acknowledged by the receiver) or informs (the alert will be
acknowledged by the receiver ). This adds significant power to the NMS by
allowing it to monitor the security of the network. It also allows the snort
sensor to exploit the features that are built into existing network management
systems.