p0f3 v3 RC Released

P0f is a tool that utilizes an array of sophisticated, purely passive traffic fingerprinting mechanisms to identify the players behind any incidental TCP/IP communications (often as little as a single normal SYN) without interfering in any way.

Some of p0f’s capabilities include:

Highly scalable and extremely fast identification of the operating system and software on both endpoints of a vanilla TCP connection – especially in settings where NMap probes are blocked, too slow, unreliable, or would simply set off alarms.
Measurement of system uptime and network hookup, distance (including topology behind NAT or packet filters), user language preferences, and so on.
Automated detection of connection sharing / NAT, load balancing, and application-level proxying setups.
Detection of clients and servers that forge declarative statements such as X-Mailer or User-Agent.

The tool can be operated in the foreground or as a daemon, and offers a simple real-time API for third-party components that wish to obtain additional information about the actors they are talking to.

Common uses for p0f include reconnaissance during penetration tests; routine network monitoring; detection of unauthorized network interconnects in corporate environments; providing signals for abuse-prevention tools; and miscellanous forensics.

Changelog v3 RC

Version 3 is a complete rewrite, bringing you much improved SYN and SYN+ACK fingerprinting capabilities, auto-calibrated uptime measurements, completely redone databases and signatures, new API design, IPv6 support (who knows, maybe it even works?), stateful traffic inspection with thorough cross-correlation of collected data, application-level fingerprinting modules (for HTTP now, more to come), and a lot more.