From time to time somebody will offer up sacrificial boxes on the internet for people to hack against. The reasons are many and varied. Sometimes companies want to show off their latest firewalls, hackers want to practise really securing a LINUX box, or someone just offers it up for fun, knowing they can log and watch and enjoy as people test their system security. If you take part in one of these wargames, be sure that it is exactly what it purports to be. All the activities are likely to be logged and anyone, including government and state investigators, or private security companies could be running these wargames.
The information gathered from such activities helps to build up traffic analysis databases, showing where attacks come from, and helps log hacker "fingerprints", showing the MODUS OPERANDI in attack patterns and techniques. With this information, security companies stand a better chance of finding hackers once they been attacked, because all they have to do is look at the cracking techniques used in the hack and then match to any records from the wargames they previously hosted. As I said, if you want to crack system security legally by playing one of these wargames, then be careful, because it might not be what it seems.

(http://www.try2hack.nl http://www.victimcylant.com etc....)