Rootkit Hunter scans files and systems for known and unknown rootkits, backdoors, and sniffers. The package contains one shell script, a few text-based databases, and optional Perl modules. It should run on almost every Unix variety except Solaris and NetBSD.
You can download it from the following link: https://packetstormsecurity.com/files/download/36312/rkhunter-1.2.1.tar.gz
Source: https://packetstormsecurity.com/files/36312/rkhunter-1.2.1.tar.gz.html