ftp dir returns java error

I get the following error on an ftp object. help?

>> dir( fo)
Error using ftp/dir (line 64)
Java exception occurred:
java.net.SocketException: Operation timed out
  at java.net.SocketInputStream.socketRead0(Native Method)
  at java.net.SocketInputStream.read(SocketInputStream.java:152)
  at java.net.SocketInputStream.read(SocketInputStream.java:122)
  at sun.nio.cs.StreamDecoder.readBytes(StreamDecoder.java:283)
  at sun.nio.cs.StreamDecoder.implRead(StreamDecoder.java:325)
  at sun.nio.cs.StreamDecoder.read(StreamDecoder.java:177)
  at java.io.InputStreamReader.read(InputStreamReader.java:184)
  at java.io.BufferedReader.fill(BufferedReader.java:154)
  at java.io.BufferedReader.readLine(BufferedReader.java:317)
  at java.io.BufferedReader.readLine(BufferedReader.java:382)
  at org.apache.commons.net.ftp.FTP.__getReply(FTP.java:294)
  at org.apache.commons.net.ftp.FTP.sendCommand(FTP.java:490)
  at org.apache.commons.net.ftp.FTP.sendCommand(FTP.java:534)
  at org.apache.commons.net.ftp.FTPClient._openDataConnection_(FTPClient.java:476)
  at org.apache.commons.net.ftp.FTPClient.listNames(FTPClient.java:1950) 
>> fo

fo = 

    FTP Object
       host: ftp.box.com
       user: [e-mail]
        dir: /philsea10_data
       mode: binary

[Walter Roberson]

Are you using a proxy? ftp does not support proxy.

Answer 1

[Soumya Saxena]

I understand that you are getting a java exception when using the “dir” command on a ftp object.

This may be caused by a firewall which is blocking an "active" ftp connection. Many firewalls are configured to allow only “passive” FTP connections.

In my opinion you can debug this issue by using an external debugger like WireShark. This will allow you to intercept the commands being sent by MATLAB to the FTP server and compare them to the commands being sent by another FTP client to the server that is working fine. In this way, you may check possible incompatibilities.