SFTP – How to Change SFTP Default Directory

Maybe a firewall is blocking your connection? Run iptables -nvL on server and look if 21 port is closed. Othewise try to connect to your server locally by ftp program.

If you're experiencing the same issue as I am you will find in your server's auth log that proftpd first tries pam_unix before falling back to the configured authentication method. For me I am using authuserfile and not Unix authentication. As with you my first attempts always fail and the second attempts always succeed.

The proftpd documentation would have you believe that AuthPAM off disables pam authentication entirely. I find this to be inaccurate as proftpd continues to try pam even with AuthPAM off and PersistendPassed off.

I recompiled proftpd without pam and now I can login the first time. The problem is that most distributions ship binary packages and may not even give you this ability. If that is the case then you could always modify pam to use the authentication method you require.