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 capability, with alerts being sent to syslog or a separate "alert" file. As of version 1.1 it can also send WinPopup messages via Samba.