Hacking Linux Server is a complex matter, specially because the meaning of hacking is sometimes non-specific. Is it to use computer programs made by other programmers to compromise security on a vulnerable server or platform and not get caught? Well, people generally consider this script kiddioting (kidding + idiotic) and for a very long time I did too, but nowadays if you can go from base line (ground zero, or whatever you want to call it) to actually having full access (UID 0) on a machine and keep it so that a system administrator cannot detect you, then you must at least have some credit and if you were able to create simple scripts to achieve this, you DID hack something, so it’s hacking!

For no particular reason, I've collected a lot of tools and trick for tunneling one network through another.  In addition to OpenVPN, IPSec, and other dedicated  tools designed to provide Virtual Private Network functionality, I've played around a lot with running IP traffic through SSH, SSL, and even plain HTTP tunnels.

This is typically done when you want to get around someone's firewall, but also can be convenient for bridging local area protocols (such as old school LAN games like DOOM) across the Internet.  Yeah, OK, but mostly its for piercing firewalls.

Security researcher Dan Rosenberg presents a small demo program which combines several security holes to obtain root privileges on Linux systems on Full Disclosure Security mailing list.

He combined some existing vulnerabilities with the vulnerability discovered by Nelson Elhage in connection with the kernel’s thread management and troubleshooting routines (CVE-2010-4258).With this exploit, an attacker can potentially exploit an OOPS to write a null byte into the kernel’s memory area.