10 Basic Linux Security Tips to Implement
The following is a list of rules and tips you might find useful in dealing with basic security concerns:
1) Avoid doing your regular jobs when you are logged in as root. This reduces the risk of getting a cuckoo egg or a virus and protects you from your own mistakes.
2) If possible, always try to use encrypted connections to work on a remote machine. Using SSH (secure shell) to replace telnet, ftp, rsh, and rlogin should be standard practice.
3) Avoid using authentic method based on ip address alone.
4) Try to keep the most important network-related packages up-to-date and subscribe to the corresponding mailing lists to recieve announcements on new versions of programs such as bind, postfix, and ssh. The same should apply to software relevant to local security.
5) Disable any network services you do not absolutely require for your server to wok properly. This will make your system safer. Open ports, with the socket state LISTEN, can be found using the netstat program.
6) RPM packages from SUSE are digitally signed. You can verify the integrity of any SUSE RPM package by entering this on concole: rpm — chechsig package.rpm . The needed public gpg-key is copied to the home directory of root upon installation.
7) Check your backups of user and system files regularly. Remember that if you do not test whether the backup will work, its as good as useless.
8) Check your log files. Whenever possible, write a small script to search for suspicious entries.
9) Use firewall to enhance the security provided by tcpd (tcp wrapper)
10) Design your security measure to be redundant. A message seen twice is better than no message at all.
Originally from : http://www.linuxhaxor.net/2007/11/21...-to-implement/