The author is introducing seven applications: Nmap, Ethereal, Showtraf, TCPDump, Nemesis, John the Ripper and Netpass. Unfortunately though he is not linking to the tools but only describing them. That means a little googling has to be done on your site to find this applications. Not a big problem though.

Update: The article is no longer available on the website. That’s not a huge problem considering that it dated back to 2006 and that the tools introduced back then may not be available anymore. Here are links and short descriptions of all tools that are still actively in development:

TCPDump: A command line packet analyzer.

Tcpdump prints out a description of the contents of packets on a network interface that match the boolean expression. It can also be run with the -w flag, which causes it to save the packet data to a file for later analysis, and/or with the -r flag, which causes it to read from a saved packet file rather than to read packets from a network interface. In all cases, only packets that match expression will be processed by tcpdump.

John the Ripper: A password cracker.

John the Ripper is a fast password cracker, currently available for many flavors of Unix, Windows, DOS, BeOS, and OpenVMS. Its primary purpose is to detect weak Unix passwords. Besides several crypt(3) password hash types most commonly found on various Unix systems, supported out of the box are Windows LM hashes, plus many more with contributed patches.

Nemesis:

TCP/IP Packet Injection Suite The Nemesis Project is designed to be a commandline-based, portable human IP stack for UNIX/Linux. The suite is broken down by protocol and should allow for useful scripting of injected packet streams from simple shell scripts

Nmap: Free security scanner.

Nmap (“Network Mapper”) is a free and open source (license) utility for network exploration or security auditing

Etheral: A network protocol analyzer.

Ethereal® is used by network professionals around the world for troubleshooting, analysis, software and protocol development, and education. It has all of the standard features you would expect in a protocol analyzer, and several features not seen in any other product.