Very secure FTP Daemon, a secure, fast FTP server for UNIX systems, including Linux.

The best FTP Server alternative to Viper FTP is vsftpd, which is both free and Open Source. If that doesn't work for you, our users have ranked more than 25 alternatives to Viper FTP, but unfortunately only two of them are FTP Servers.
Very secure FTP Daemon, a secure, fast FTP server for UNIX systems, including Linux.

File transfers using:
FTP
FTPS (Implicit and Explicit FTP over SSL).
SFTP (FTP over SSH). Login with password or RSA/DSA OpenSSL (Traditional SSLeay PEM) or ConnectBot (PKCS#8 PEM) private key.
multiple file and directory transfers
resume transfers support
clean and.