Connection problem from other countries

Jul 29, 2013 at 12:26 AM
Thank you for this project! I set up an FTP server and hosted on west US server, and everything works great from my workstation located in California. However, I have some friends from south Asia, like Indonesia, or China, are having some problem to connect to the server in passive mode.

From the connection log on the client, it does go through the user name and password validation process, but once the PASV command is sent, the response from server becomes:
500 The server returned invalid response for PASV command.

I checked the code, there is no way the FTP server will return 500 at this point. The problem seems only affecting users with slow network and long network delays. My friends also tried a regular FTP server hosted in godaddy server, everything works. That makes me think this project might need some fix in flaky network environment?

Has anyone seen similar issues? Thanks a lot!