RootPrompt.org: Armoring Linux

[ Thanks to Noel
for this link. ]

“Organizations throughout the world are adopting Linux as their
production platform. By connecting to the Internet to provide
critical services, they also become targets of opportunity. To help
protect these Linux systems, this article covers the basics of
securing a Linux box. The examples provided here are based on Red
Hat 6.0, but should apply to most Linux distributions.”

“The best place to start in armoring your system is at the
beginning, OS installation. Since this is a production system, you
cannot trust any previous installations. You want to start with a
clean installation, where you can guarantee the system integrity.
Place your system in an isolated network. At no time do you want to
connect this box to an active network nor the Internet, exposing
the system to a possible compromise. I personally witnessed a
system hacked by a script kiddie within 15 minutes of connecting to
the Internet. To get critical files and patches later, you will
need a second box that acts as a go between. This second box will
download files from the Internet, then connect to your isolated,
configuration “network” to transfer critical files or burn the
patches to a CDROM.”

“Once you have loaded the installation package, patches, and
rebooted, we are now ready to armor the operating system. Armoring
consists mainly of turning off services, adding logging, tweaking
several files, and configuring TCP Wrappers.”

Complete
Story