Unable to connect using SFTP/SSH


I am trying to connect using SFTP over SSH, but keep getting the following authentication error:


[21:12:40] SmartFTP v4.0.1133.0
[21:12:40] Resolving host name ""
[21:12:40] Connecting to Port: 2232
[21:12:41] SSH-2.0-OpenSSH_4.3
[21:12:41] Starting SSH session. Remote Id: "SSH-2.0-OpenSSH_4.3"
[21:12:41] SSH protocol version reply. Client Id: "SSH-2.0-SmartFTP FIPS"
[21:12:41] Key Exchange Algorithm: diffie-hellman-group-exchange-sha1
[21:12:44] Key exchange completed.
[21:12:44] Host Key Algorithm: ssh-rsa
[21:12:44] Client to Server Encryption: aes256-ctr
[21:12:44] Server to Client Encryption: aes256-ctr
[21:12:44] Session MAC: hmac-sha1
[21:12:44] Client to Server Compression: zlib@openssh.com
[21:12:44] Server to Client Compression: zlib@openssh.com
[21:12:44] Requesting service "ssh-userauth".
[21:12:44] RTT: 662.978 ms
[21:12:44] User authentication failed.
[21:12:44] Client closed the connection.
[21:12:44] Connect failed. Waiting to retry (30s)..

Following are my settings in SmartFTP for this connection:

General Tab:
1. Protocol: SFTP over SSH
2. Login Type: Username & Password
3. I have given username for which SSH login is configured
4. Password is not given

SSH Tab:
1. Authentication
- Use Favorite Settings
- Private/Public Key in enabled and have disabled all others

In Private Key section:
- Whenever I load a private key, it immediately says: Failed to load key file. The key file is in OpenSSH format
- All other are default settings.

Please help.


Wrong username/password.

Wrong username/password.

I am able to connect using WinSCP with leaving password field blank!. So how come it can be a problem?
Also please let me know what value I should give in Password field, (when I am using key based authentication) or should I choose Username only? in General Tab


Please email the (or any) private key that fails to load to support@smartftp.com
Thank you.

Quick follow up: The customer was using the public key file (.pub) instead of the private key file (.ppk).