Rootkit Hunter is a Unix-primarily based scanning tool that scans for rootkits, backdoors and possible local exploits. It does this by comparing SHA-1 hashes of vital files with known good ones in online database, looking for default directories (of rootkits), improper permissions, hidden records data, suspicious strings in kernel modules and particular tests for Linux or FreeBSD. Most instances rootkits are self-hiding toolkits utilized by blackhats, crackers and script kiddies, to keep away from the attention of the system admin. If you’re unsure  as to whether your system is compromised, you will get a second opinion from sources such as Linux-oriented forum. If your system is contaminated with a rootkit, cleaning it up will not be an option. Restoring can be not an option unless you might be expert, and have autonomous and an impartial means of verifying that the backup is clear, and does not include misconfigured or stale software. Never trust a potentially compromised machine! Basically a clean install of the OS is always advisable after backing up the system.