Linux dedicated server security does not have to be overly complex. With the right tools, you can accomplish your security goals with efficiency. One such project, Sentry Tools, offers host-level security services for Linux and other Unix-like operating systems.
Sentry Tools includes: PortSentry, Logcheck/LogSentry, and HostSentry. PortySentry protects against portscans. LogSentry automates log file auditing, and HostSentry detects suspicious login activity. All of these tools can run in the background and, as the name “sentry” implies, stand guard over your server day and night.
These tools are designed to be proactive in server security, rather than reactive. That means they are meant to keep trouble out rather than mitigating it once it has found its way in. As some users of the tools have commented, it may help you sleep a little sounder at night and keep you from having to wake up at 2 AM to stop an intrusion attempt.
Best of all, Sentry Tools is free software, released under the GNU General Public License (GPL). That means it is free for you to use, download, share, modify, and redistribute under the same license.