Nmap also offers flexible target and port specification, decoy scanning, determination of TCP sequence predictability characteristics, sunRPC scanning, reverse-identd scanning, and more. PortSentry PortSentry is part of the Abacus Project suite of security tools. It is a program designed to detect and respond to port scans against a target host in real-time. It runs on TCP and UDP sockets and works on most UNIX systems. Advanced stealth detection modes are available under Linux only and detect SYN, FIN, NULL, XMAS, and Oddball packet scans.
All modes support real-time blocking and reporting of violations.
The current config file lists over 80 OS's and versions. It can detect Linux Kernel versions and TCP responses from devices such as routers, terminal servers, printers, etc. Snort Snort is a lightweight network intrusion detection system, capable of performing real-time traffic analysis and packet logging on IP networks. Snort uses a flexible rule based language to describe traffic that it should collect or pass, and a modular detection engine. Snort has a real-time alerting capability, with alert mechanisms for syslog, a user specified file, a UNIX socket, or WinPopup messages to Windows clients using Samba's smbclient.