OpenSSH is not the only one capable of doing file transfers over a secure line called SFTP (ShellFTP/SecureFTP/SSHFTP). ProFTPd can also do it using mod_sftp and the support has been added on version 1.3.3. Why choose SFTP over FTPS? Simple, SFTP transfers all data over 1 single port!!! This means you do not have to fiddle around with needed passive ports on your firewall setup.

Now here’s to install and run a separate SFTP server:

1. Download and install the EPEL repo (EPEL)

2. Install proftpd with:

yum install proftpd

3. Then edit your proftpd config file and add following content somewhere in the config file (somewhere at the end i suppose should be best):

LoadModule mod_sftp.c
<IfModule mod_sftp.c>
        SFTPEngine On
        SFTPHostKey /etc/ssh/ssh_host_rsa_key
        SFTPLog /var/log/proftpd/sftp.log
        SFTPOptions     IgnoreSFTPUploadPerms
        SFTPClientMatch ".*" channelWindowSize 256MB
        SFTPCompression delayed
</IfModule>

3b. (Optional) Should you want to allow login for users with invalid shells (e.g. /bin/false or /sbin/nologin), do the following:

RequireValidShell   off
# AuthOrder         mod_auth_pam.c* mod_auth_unix.c

4. start the proftpd server

service proftpd start

For more infos about the sftp module visit the manual page