How can I secure a Debian installation?

[Jon Danniken <danniken@q.com>]

Hello list,

I recently came across a posting by an individual who got his
Debian machine compromised due to a number of security problems, one of
which was the default installation and running of sshd with
"PermitRootLogin =
Yes".  in /etc/ssh/sshd_config.

So I checked the Debian installation that I put on my laptop a month ago
(from the Wheezy net install CD), and sure enough I had the same
vulnerability
(I fixed it by changing the "PermitRootLogin" value).

Fortunately I have been running behind my router, and remain unscathed,
but it caused me to wonder what other vulnerabilities are present out of
the box that I need to address, especially if I should take the laptop
out with me and connect to a public network.

Besides the sshd root login, what else do I need to disable/fix on this
machine?

Thanks,

Jon