Simple steps for securing your Linux system
Safety First

A good reputation does not protect your Linux systems from attack. We'll show you some tips for detecting and warding off intruders.
Security is a problem for any computer that faces the Internet, and the solution can be as big and comprehensive as you want to make it. Firewalls, penetration testing, and Intrusion Prevention Systems (IPS) are all important, but you can do a lot for securing your system before you even start adding these critical security layers. This article highlights some basic security steps that are so easy they are often overlooked.
If you are administering a Linux system that you can install from scratch, keep in mind that fewer services on the system means fewer avenues for attack, so one worthy approach is to leave out everything you don't really need. Many distributors offer specially designed minimal versions for reducing the attack footprint. You can then set up a miniature Linux and import only the packages you genuinely need.
Once the system is running, keep it up to date. Security updates, in particular, need to be checked daily and installed immediately. Many distributions have automated processes for installing security updates. On Debian and Ubuntu, for instance, the buzzword is "unattended upgrades " [1].
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