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. Version 3 is a complete rewrite of the original codebase, incorporating a significant number of improvements to network-level fingerprinting, and introducing the ability to reason about application-level payloads (e.g., HTTP). To build and install the optional signature and API tools, specify TOOLS=yes to the SlackBuild, for example TOOLS=yes sh p0f.SlackBuild If you are upgrading from p0f version 2.0.8, please note that the files /etc/p0f/p0f{a,o,r}.fp are no longer used and can be removed.