1. A vulnerability scanning tool designed to hunt for many ways into a system. Much hyped at the time; people feared that it would give a powerful tool into the hands of hackers everywhere. In practice, it was a dud: it was much to "noisy", was already outdated by the time it was released, was impossible to setup, and hasn't been really maintained. From Hacking-Lexicon

2. Program designed to assess the security status of a computer or local area network (LAN) connected to the Internet. The program determines whether Internet-related software is misconfigured in a way that could render the system vulnerable to a cracker. The program is controversial because intruders as well as system administrators can use it to find loopholes. The controversy deepened when the program's authors, Dan Farmer and Wietse Venema, made the program publicly available through the Internet. From QUECID