“Whether your firm has been running Linux for awhile or is one
of a growing number of companies that have only recently moved to
Linux on their networks, you may be concerned about how to secure
Linux. If you’re not, you should be. ISS (Internet Security
Systems), the security firm founded by Christopher Klaus in 1994,
has announced that it will be the first company to offer a
professional Linux security training course….”
“But he did publish the source code for the ISS port
scanner, which allows you, via the Internet, to look across a
network and see what ports are open on a specific machine or range
of machines. He wrote ISS in 1992. In September of 1993, he
posted the full source code to version 1.00 of ISS to the
comp.sources.misc newsgroup on Usenet.”
“ISS is still available on the Internet at security and hacker
sites alike. I found it at Purdue University’s CERIAS FTP site. In
any event, tool usage is a habit shared by both those interested in
maintaining site security and those interested in violating
it.”