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.
w3af, is a Web Application Attack and Audit Framework. The w3af core and it's plugins are fully written in python. The project has more than 130 plugins, which check for SQL injection, cross site scripting (xss), local and remote file inclusion and much
Skipfish is an active web application security reconnaissance tool. It prepares an interactive sitemap for the targeted site by carrying out a recursive crawl and dictionary-based probes. The resulting map is then annotated with the output from a number of active (but hopefully non-disruptive) security checks. The final report generated by the tool is meant to serve as a foundation for professional web application security assessments.
advchk is a tool for monitoring the security of installed software. Advisory Check gathers security advisories using RSS / RDF / XML feeds, compares them against a list of known software, and alerts you if you`re vulnerable.
