Rkhunter (Rootkit Hunter) is a Unix-based tool that scans for rootkits, backdoors and possible local exploits. It does this by comparing MD5 hashes of important files with known good ones in online database, searching for default directories (of rootkits), wrong permissions, hidden files, suspicious strings in kernel modules, and special tests for Linux and FreeBSD.

Step 1: Downloading, Installing and Updating

Step 2: Adding daily cron job

Create the file /etc/cron.daily/rkhunter.sh with the following contents.

Change YourServerNameHere to your hostname and name@domain.com to your mail address.

Correct the permissions.

Your Server will be scanned regularly and the result will be sent to the mentioned mail address.