FTP setting for Self-hosted CDN in wordpress W3 Total Cache

I want to use self-hosted CDN for my wordpress blogs, but I don't have ftp server installed on my VPS. I usually use server IP with ssh root login on ftp client(port is not 22). I've tried to use the same info for CDN, but got this error. Do I really need to install ftp server? Thanks.

Error: Incorrect login or password (ftp_login() [function.ftp-login]: Permission denied.).