Psad Intrusion Detection System

The Port Scan Attack Detector psad is a lightweight system daemon written in is designed to work with Linux iptables/ip6tables/firewalld firewalling code to detect suspicious traffic such as port scans and sweeps, backdoors, botnet command and control communications, and more. It features a set of highly configurable danger thresholds (with sensible defaults provided), verbose alert messages that include the source, destination, scanned port range, begin and end times, TCP flags and corresponding nmap options, reverse DNS info, email and syslog alerting, automatic blocking of offending IP addresses via dynamic configuration of iptables rulesets, passive operating system fingerprinting, and DShield reporting. In addition, psad incorporates many of the TCP, UDP, and ICMP signatures included in the Snort intrusion detection system. to detect highly suspect scans for various backdoor programs (e.g. EvilFTP, GirlFriend, SubSeven), DDoS tools (Mstream, Shaft), and advanced port scans (SYN, FIN, XMAS) which are easily leveraged against a machine via nmap. psad can also alert on Snort signatures that are logged via fwsnort, which makes use of the iptables string match extension to detect traffic that matches application layer signatures. As of the 2.4.4 release, psad can also detect the IoT default credentials scanning phase of the Mirai botnet.