nmap package obsoleted?

[rex <lists@pgrworld.com>]

Hello, I'm trying to install nmap, and so I did "apt-get install nmap",
but I get this:

	Reading package lists... Done
	Building dependency tree... Done
	Package nmap is not available, but is referred to by another package.
	This may mean that the package is missing, has been obsoleted, or
	is only available from another source
	E: Package nmap has no installation candidate

when I do "apt-cache pkgnames | grep nmap", I get nmap.

googling shows me that nmap is at
http://packages.debian.org/stable/net/nmap.html, but I get "No such package"

my sources.list file show:

	#
	# deb cdrom:[Debian GNU/Linux 4.0 r3 _Etch_ - Official i386 DVD
Binary-1 20080217-11:31]/ etch contrib main

	deb cdrom:[Debian GNU/Linux 4.0 r3 _Etch_ - Official i386 DVD Binary-1
20080217-11:31]/ etch contrib main

	deb http://security.debian.org/ etch/updates main contrib
	deb-src http://security.debian.org/ etch/updates main contrib

I did an "apt-get update" but that didn't work.

Please help.  Thanks!