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SSL with FTP Voyager and a NAT Proxy Server  -  KB Article #1025

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The problem is that NAT proxy servers "interpret" the FTP commands and responses, and make connections and accept connections for the server and/or client. When SSL enters the fray, the NAT proxy server (or router) doesn't have any way to decrypt the SSL command connection, thereby causing FTP to fail when SSL is used.

One common solution is to use PASV mode, which is found in View | Options | Connection and is labeled Use PASV mode for all sites. Select this option, and it may work.

Enable PASV mode

Your best bet is to install a proxy server like AllegroSurf, assign the server an external IP address, then disable all protocols on that computer except for TCP/IP. Then connect it to your LAN with TCP/IP only, and connect the rest of your computers to the SOCKS5 proxy server. Since the FTP client controls the proxy server through SOCKS (i.e., telling it where to connect and where to listen), SSL through a proxy server works. FTP Voyager works in both PASV and normal modes when using SOCKS and SSL.

The same holds true for proxy servers which interpret FTP commands (such as user@site style proxy servers). The proxy server is unable to "read" the commands since they're encrypted and cannot connect or accept connections. If possible, in this situation disable the interpreting functionality of your proxy to resolve the issue.

If you still experience trouble after following these steps, you may contact the RhinoSoft Technical Support Team for more help.