A good way to protect your Linux machine, when you don't know too much (yet) about security is by making the following very simple changes in two files: /etc/hosts.deny and /etc/hosts.allow

First, in /etc/hosts.deny add the following line:

ALL : ALL

This is meant to block (1st ALL) services that your computer provides from anybody (2nd ALL) that may try to log in to your machine. Then, if you have more than one computer (a small business or home network) you should add this line in /etc/hosts.allow

ALL : 192.168.0.

This will allow local users to access the computer. There's no reason not to let people locally to log in via the SSH program that we mentioned before. This is OK as long as you trust them. If you are a home user you're probably safe but if you are using this to set up a small business network, I would be a bit more careful. There are all kinds of stories about disgruntled employees taking liberties, revenge, extended vacations with company money, etc.

One last word: This ISN'T a substitute for a firewall or a serious security set up.

Article Source: Linux.org

A note from the Wise Old Blogger:

Windows is currently more vulnerable to viruses, trojans and worms because malwares were written to attack the Windows operating system, but as Linux grows in popularity, expect similar problems. This August 18, 2003 article, "Trojan Horse attacks GNU Project" describes the growing threat of viruses to the Linux operating system.

If you are setting-up Linux up on a small business or home network, seek a professional security consultant's help and try a search engine like google.com to search for "hardening linux" or "linux security" and substitute your type of linux for the word 'linux' in your search. Example: "debian security", "hardening red hat", etc. Here are some of my search results:

http://linuxtoday.com/security/2000050103004SC

Debian/Linux:

Security FAQ's: http://www.debian.org/security/faq

General info: http://www.debian.org/security/

Security Manual: http://www.debian.org/doc/manuals/securing-debian-howto/index.en.html

Have Fun!