TurboFTP client has problem showing remote listings when connecting to an FTPS server.

Article Details
URL: http://www.tbsoftinc.com/support/index.php?_m=knowledgebase&_a=viewarticle&kbarticleid=149
Article ID: 149
Created On: 24 Jul 2012 03:53 AM

Answer The remote listings can't be retrieved (LIST/MLSD command failed) because the data connection can't be established.

When this happens, using the PASV mode (enabling Site Settings | Connection | PASV mode or globally in Options | Firewall | Use PASV mode) often does the trick. However, it won't work if the remote FTPS server is sitting behind a NAT-enabled firewall. Possible solutions to the problem are:

1. If you are using explicit FTPS, enable the 'Clear Command Channel (CCC)' option under Site Settings | Advanced tab of TurboFTP client. This way the command channel is not encrypted and the router/firewall can see it in clear text, so that the router/firewall can rewrite the FTPS server's response to PASV command, and route the client's upcoming connection request to the port opened by the server. However be aware that with clear command channel the login credentials are sent in plain text as in normal FTP.

2. If you are using implicit FTPS, it is more difficult to establish a data channel for the server and the client in this scenario. The reason is that in implicit FTPS both command and data channels are encrypted, as such there is virtually no way for the router/firewall to see the server and the client's negotiation of IP/port to establish the data channel.

3. Switching to SFTP will eliminate this problem.