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 clone.
You can download it from the following link: https://packetstormsecurity.com/files/download/33015/rkhunter-1.0.5.tar.gz
Source: https://packetstormsecurity.com/files/33015/rkhunter-1.0.5.tar.gz.html