FTP is an old protocol and there has been many variations of it’s implementations over the years. These servers listed below vary in many details and far from a complete list of Linux FTP servers out there. But these are few of the most popular Linux FTP servers out there:

1. ProFTPd This server, http://proftpd.org, is one of the more popular of the very complex FTP servers. It ships with most major Linux distributions. Its configuration file is modeled after that of Apache, and the server supports many advanced features.
2. vsftpd This server aims to excel at security, stability, and speed. In doing so, its developers have chosen to ignore some of the more advanced features of servers such as ProFTPd and WU-FTPD. If you don’t need those features, this tradeoff may be more than acceptable. You can learn more from its website, http://vsftpd.beasts.org.
3. WU-FTPD The Washington University FTP Daemon (WU-FTPD) is an old standard in the Linux world. Unfortunately, it’s collected more than its fair share of security problems and isn’t the speediest FTP server available. For these reasons, it ships with fewer Linux distributions today than in years past. Its main website is http://www.wu-ftpd.org.
4. PureFTPd This server, headquartered at http://www.pureftpd.org, is another FTP server that emphasizes security. SuSE ships with a version of this server.
5. oftpd This server is unusual because it’s designed to function only as an anonymous FTP server; it doesn’t support logins using ordinary user accounts. This feature can be appealing if you only want to run an anonymous server, but it makes this server unsuitable for many other purposes. It’s available from http://www.time-travellers.org/oftpd/.