Links for testing website security & weak areas for penetration

https://www.kali.org/ Penetration Testing Redefined with the Kali Linux Distribution
http://www.irongeek.com/i.php?page=videos/web-application-pen-testing-tutorials-with-mutillidae#determine-server-banners-using-netcat-nikto-and-w3af Web Application Pen-testing Tutorials With Mutillidae
http://www.irongeek.com/i.php?page=mutillidae/mutillidae-deliberately-vulnerable-php-owasp-top-10
https://www.joedog.org Siege is an http load testing and benchmarking utility.
http://www.cyberciti.biz/tips/linux-security.html
http://www.openwall.com/john/
http://www.l0phtcrack.com/