How can this happen? And if it does, what can someone do? I just heard that one of our university solaris server got hacked and it would stop all of the people access to it. How can someone hacked into a Linux or Solaris server? Is there a port open a whole or something, just a reminder I'm not really into hacking and stuff so I don't know much, I just want to know how a person can hack into one's computer? and what can that person do to your computer or server? Basically I'm just curious.

80% of attacks come from the inside, so I've heard...
I gues most of the reminaing 20% are due to bad passwords and poor security policies.

Failure to applying security patches/updates in a prompt manner is also a killer when it comes to getting cracked. All it take is one unpatched vulnerabiliity and someone with very minimal computer/programming skills can easily take complete control of a server whether it's Windows, Linux, Solaris or OpenBSD for that matter.

ANY system can be attacked/hacked/cracked/comprimised. Windows just is usually easier due to have services being on by default. Windows is based on DOS which was intended for home use. UNIX was designed for multi user use. Therefore it was designed logically and in a secure manner. The best OS for security will probably be your *BSD line with Linux and Solaris following this. To test your system for open services and ports use nmap which can be obtained from www.insecure.org although usually installed by default on Linux systems. All good sysadmins periodically test their systems with this excellent tool.