Linux Rootkit v4.1 is based on Lord Somers LRK4 but several things are fixed. Includes a better find patch, fixed install of pidof / killall, fixed rshd patch, compilation fixes, and more. Released 11-may-2000, tested on Linux kernel 2.2.6, Slackware 4.0.
You can download it from the following link: https://packetstormsecurity.com/files/download/22600/lrk-4.1.tar.gz
Source: https://packetstormsecurity.com/files/22600/lrk-4.1.tar.gz.html