What is "pure-ftpd"

Pure-FTPd is a free ( BSD license) FTP Server with a strong focus on software security. It can be compiled and run on a variety of Unix-like computer operating systems including Linux, OpenBSD, NetBSD, FreeBSD, DragonFly BSD, Solaris, Tru64, Darwin, Irix and HP-UX. It has also been ported to Android.