Slirp is a TCP/IP emulator which turns an ordinary shell account into a (C)SLIP/PPP account. This allows shell users to run ftp, netscape, CUSeeMe, etc.
You can download it from the following link: https://packetstormsecurity.com/files/download/13346/slirp-1.0e.tar.gz
Source: https://packetstormsecurity.com/files/13346/slirp-1.0e.tar.gz.html