You're walking along a thin line in my opinion, don't cross it! There's a small difference between what you refer to as hacking (search the internet for the correct term, or here on LQ there's also a thread discussing difference between hacking and cracking I believe) and penetration testing. The one you are referring to is against the LQ rules when it comes to posting whilst penetration testing is not AFAIK. If you want to learn anything on the subject, search Google, read documentation, download something like BackTrack
and learn how to use the tools in it for penetration testing.