SELECT SECURITY LEVELS USING MSEC

Mandrake Linux comes with a wonderful utility called msec (which stands for Mandrake Security) that allows you to select different security levels for your system. It offers six security levels ranging from level 0 (Welcome to Crackers) to level 5 (Paranoid). Most Linux distributions typically use the options found in level 3 (Medium).

Based on the security level you have chosen, msec changes the operation of your system. The security level is selected during the install, but can be modified at any time by the root user simply by executing the following, where [level] is the security level from 0 to 5:

# msec [level]

Some of the options with which msec deals are the root and user umask (default file permissions), the shell timeout, whether or not to deny network services by default, and whether or not to print a user list in kdm or gdm (the GUI login display managers). It also checks for other network options such as whether to ignore ICMP echo requests (pings), whether or not to ignore bogus network error responses, and also whether or not to check to see if the network card is in.

You use promiscuous mode to allow the computer to sniff packets not specifically destined for it. A few other options include whether or not it will log everything to the console (usually tty12), whether users can reboot the system as nonroot, and whether or not users can use the cron andat scheduling daemons.

While msec isn't the perfect catchall security implementation, it does do a fair amount of system hardening, provided you give it the proper security level. While a level 3 system is moderately secure, a level 4 system is more appropriate for systems connected to the internet, and a level 5 system is ideal for network.