FTP component timing out after 40 minutes

Question

We use Rebex FTP component to download files from FTP server. In our code we didn’t set the timeout property for connection.

I just wanted to know, what is the default timeout for a FTP connection. As I can see from the logs this connection is getting timed out after around 40 minutes. But I searched and the default timeout should be 60 seconds.

Could you please help me to increase this timeout period up to 1 hour?

Here is an excerpt from the log:

2013-03-18 15:37:17.670 INFO Ftp(1) Command: TYPE I
2013-03-18 15:37:17.763 INFO Ftp(1) Response: 200 Type set to I.
2013-03-18 15:37:17.779 INFO Ftp(1) Command: SIZE .
2013-03-18 15:37:17.888 INFO Ftp(1) Response: 550 .: not a plain file.
2013-03-18 15:37:17.888 INFO Ftp(1) Command: SIZE 'FILE NAME'
2013-03-18 15:37:18.013 INFO Ftp(1) Response: 213 1925070955
2013-03-18 15:37:18.028 DEBUG Ftp(1) Info: Starting data transfer.
2013-03-18 15:37:18.028 DEBUG Ftp(1) Info: Accepting data connection.
2013-03-18 15:37:18.044 INFO Ftp(1) Command: PORT 'PORT'
2013-03-18 15:37:18.340 INFO Ftp(1) Response: 200 PORT command successful.
2013-03-18 15:37:18.340 INFO Ftp(1) Command: RETR 'FILE NAME'
2013-03-18 15:37:18.558 INFO Ftp(1) Response: 150 Opening BINARY mode data connection for 'FILE NAME'
2013-03-18 15:37:18.589 DEBUG Ftp(1) Info: Data connection accepted from 'IP ADDRESS'
2013-03-18 16:17:01.225 INFO Ftp(1) Info: Timing out.
2013-03-18 16:17:01.225 ERROR Ftp(1) Info: Error while reading data: Rebex.Net.FtpException: Timeout exceeded.
   at Rebex.Net.Ftp.QztfFZ()
   at wWGvS.bEcmRk.BMJzdYZ(Byte[] , Int32 , Int32 )
   at wWGvS.bEcmRk.Read(Byte[] buffer, Int32 offset, Int32 count)
2013-03-18 16:17:01.225 DEBUG Ftp(1) Info: Data connection failed.
2013-03-18 16:17:01.225 ERROR Ftp(1) Info: Rebex.Net.FtpException: Timeout exceeded.
   at Rebex.Net.Ftp.QztfFZ()
   at wWGvS.bEcmRk.BMJzdYZ(Byte[] , Int32 , Int32 )
   at wWGvS.bEcmRk.Read(Byte[] buffer, Int32 offset, Int32 count)
   at wWGvS.bsWOwAZ.Read(Byte[] buffer, Int32 offset, Int32 count)
   at Rebex.Net.Ftp.bjMtzmZ(String , Boolean , Stream , Int64 , String )

Answer 1

It looks like some firewall might have blocked the connection after 40 minutes.

Here is a short explanation why increasing the timeout would not help in your case:

The default timeout in Rebex Ftp component is indeed 60 seconds. However, the counter is reset when a packet is received. So in your case a long-running transfer was running for 40 minutes (split into many packets, each time a packet was received the counter was reset, so no timeout occcured, which is correct). But then at 16:17:01.225 a packet was not received after 60 seconds (for the first time) and so the timeout correctly triggered. The packet was blocked by a buggy router along the way.

Please try the KeepAliveDuringTransfer option. This will send a NOOP command in a specified interval which will prevent the firewall from blocking packets. The option can be enabled like this:

Ftp ftp = new Ftp();

// enable the keep-alive option, sending NOOP every 600 seconds

ftp.Settings.KeepAliveDuringTransfer = true;

ftp.Settings.KeepAliveDuringTransferInterval = 600;

ftp.Connect("server", port);

ftp.Login("user", "password");

// do work

ftp.PutFile(...)

ftp.Disconnect();

If you still get the timeout with this option enabled, try lowering the ftp.KeepAliveDuringTransferInterval value.