Netcat

Netcat has been described as "a buffed up version of telnet that has many options that allow it to do many things" and "the TCP/IP swiss army knife." Some erroneously label it a hacker's tool, while many consider it a network engineer's right hand.

An article describing Netcat usage:

• http://www.datastronghold.com/security-articles/hacking-articles/netcat-usage.html

Netcat is a SourceForge project:

• http://netcat.sourceforge.net/