1. Makes your system hardened. This package is intended to help the administrator to improve the security of the system, or at least make the host less susceptible. NOTE! This package will not make your system uncrackable, and it is not intended to do so. Making your system secure involves a LOT more than just installing a package. You are recommended to read at least some documents in addition to installing this package. The documents can be found in the harden-doc package. This is of course just a start because there are LOT of information on how to make your system more secure. For more information on how to secure your system see: http://www.debian.org/doc/manuals/securing-debian-howto/ From Debian 3.0r0 APT

2. The word "harden" implies putting a shell around a computer in order to protect it from intruders. In order to harden a system, you should consider the following techniques: Patch the OS with the latest security fixes. For example, when the "ping-of-death" DoS attack came out, many people needed to patch their TCP/IP stacks to defend against it. Patch the exposed services with the latest security fixes. For example, many third-party mail servers have been vulnerable to buffer overflow exploits. These are normally fixed a few weeks after being published in the hacker community. Therefore, you need to regularly check with the software vendor for the latest patch. Remove all defaults. In order to make their software easy-to-use, vendors include default accounts, default passwords, and samples. However, these can generally be exploited by hackers. You MUST read security guidelines for the particular OS or software package (especially web-server) and carefully remove these defaults/samples, or your box WILL be hacked. For example, most Microsoft IIS 4 web-servers can be compromised with either the .htr buffer overflow or RDO exploits, because webmasters forget (or don't know) to turn them off. Remove all unnecessary services. For example, most Sun Solaris based systems can be hacked through the RPC services. Install packet filtering software. From Hacking-Lexicon