Vitux published a tutorial about scanning a Debian server for rootkits with Rkhunter.

How to scan a Debian server for rootkits with Rkhunter

Rkhunter stands for “Rootkit Hunter” is a free and open-source vulnerability scanner for Linux operating systems. It scans for rootkits, and other possible vulnerabilities including, hidden files, wrong permissions set on binaries, suspicious strings in kernel etc.

How to scan a Debian server for rootkits with Rkhunter – VITUX