Re
This will always happen in our software. It is not optional. It may be the cause of the error, but specifying a different IP for data channels is not supported.
The FTP server is specifying the port number to use for the data channel in its 227 response (see last two parameters here
2/12/2014 8:41:53 PM: 227 Entering Passive Mode (192,168,0,2,193,129)
where port number is in two high/low bit-values, so (193*256) + 129 = 49537). We're obeying that command to use that port, and getting no response. Probably firewall or router issues are blocking that port (or, a range that includes it). Or, the use of the original resolved IP number (instead of the internal IP address specified) is failing.
Note that port 21 is by no means the only port used (port-21 is only the command channel; different ports are used for data channels, usually 'agile'). Multiple data ports are used in either Active or Passive mode. Which ports are used depends on the mode. Passive ports are specified by the server, Active by the client (but both ends must have the appropriate range of ports open)
12/12/2014 8:41:53 PM: Passive ip address returned from server different from server ip.
2/12/2014 8:41:53 PM: Replacing received PASV address 192.168.0.2 by server address yyy.y.yy.yy.
This will always happen in our software. It is not optional. It may be the cause of the error, but specifying a different IP for data channels is not supported.
2/12/2014 8:41:53 PM: Opening data connection to yyy.y.yy.yy Port: 49537 (NOTE: This port number is not always consistent when I rerun the FTP test)
The FTP server is specifying the port number to use for the data channel in its 227 response (see last two parameters here
2/12/2014 8:41:53 PM: 227 Entering Passive Mode (192,168,0,2,193,129)
where port number is in two high/low bit-values, so (193*256) + 129 = 49537). We're obeying that command to use that port, and getting no response. Probably firewall or router issues are blocking that port (or, a range that includes it). Or, the use of the original resolved IP number (instead of the internal IP address specified) is failing.
Note that port 21 is by no means the only port used (port-21 is only the command channel; different ports are used for data channels, usually 'agile'). Multiple data ports are used in either Active or Passive mode. Which ports are used depends on the mode. Passive ports are specified by the server, Active by the client (but both ends must have the appropriate range of ports open)