Product Name : RKHunter
Product Version : 1.3.2
Homepage : http://www.rootkit.nl
Description : 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 Updateing

cd /usr/local/src
wget http://mesh.dl.sourceforge.net/sourceforge/rkhunter/rkhunter-1.3.2.tar.gz
tar -zxvf rkhunter-1.3.2.tar.gz
cd rkhunter-1.3.2
./installer.sh --layout default --install
/usr/local/bin/rkhunter --update
/usr/local/bin/rkhunter --propupd

Step 2: Adding daily cron job

Step 2.1: Create run-file

nano -w /etc/cron.daily/rkhunter.sh

Step 2.2: Add this text to rkhunter.sh

#!/bin/sh
(
/usr/local/bin/rkhunter --versioncheck
/usr/local/bin/rkhunter --update
/usr/local/bin/rkhunter --cronjob --report-warnings-only
) | /bin/mail -s 'rkhunter Daily Run (PutYourServerNameHere)' This e-mail address is being protected from spambots. You need JavaScript enabled to view it

Step 2.3: Chmod rkhunter.sh

chmod 700 /etc/cron.daily/rkhunter.sh

There you go! should be installed, and you will get a mail daily with a status on your system