“Until someone designs an operating system that reads minds,
security will depend on diligent configuration and administration,
no matter what OS software you use. Your Linux machine can be
extremely secure, but it’s not going to get there on its own. Here
are a few basic measures.”
“Disable Services Shut down every service not 100 percent
necessary for the specific purpose of a given machine-when in
doubt, turn it off. Any of the myriad services offered through
inetd (Linux’s “superdaemon”) may be turned off by opening the
/etc/inetd.conf file and inserting a “#” at the beginning of the
line listing the service. All of the “r” services (rsh, rlogin and
rcp) should be removed entirely and replaced, if necessary, with
OpenSSH (www.openssh.com). If possible, OpenSSH also should replace
telnet and ftp.”
“Restrict Access Use IP Chains to block unused ports and
suspicious packets (see www.Linuxsecurity.com/docs/
HOWTO/IPCHAINS-HOWTO.html for configuration specifics). Warning: IP
Chains on your hosts is a supplement to-not a replacement
for-stand-alone peri meter network firewalls.”