Can FTP have multiple TCP connection for multiple parallel file transfer

Question

While reading the FTP protocol specification from : (http://www.pcvr.nl/tcpip/ftp_file.htm). I came across this "FTP differs from the other applications that we've described because it uses two TCP connections to transfer a file". My question is, can FTP have multiple TCP connection for multiple parallel file transfer, for example can I transfer two files in parallel over two TCP connections, is this a matter of customization or standardization?

Chagall

Answer 1

While it would be theoretically possible to make an FTP server support multiple, concurrent transfers, it's not supported by the RFC or any known implementation.

The block is a simple one in that the control connection, after receiving a transfer request, does not return a final status or accept new commands until the data transfer is completed. Thus, though you could queue up another transfer request it wouldn't actually be processed by the server until the current one completes.

If you want multiple file transfers, just log into the FTP server multiple times using different programs or command-line windows and have each initiate a transfer.

Ansermet

Answer 2

No it can't. FTP uses a control connection for sending commands and a data connection that exists for the duration of the file transfer or directory listing retrieval, that's it.

For more information you can consult RFC 959, which defines the specs of the FTP protocol.

Mcgriff

You can however log in with the same user several times simultaneously (limited by server settings). – Foskett

Answer 3

File Centipede download manager actually creates multiple connections to download the file from the FTP server. It helps to increase the download speed significantly, sometimes tenfold, if you are downloading large files (hundreds of MB or even 20+ GB).

There is also CuteFTP from Globalscape, which supports up to 4 concurrent dowload streams for 1 file:

and my favourite so far aria2 lightweight command-line tool for Linux (can be also run from Ubuntu for Windows) which you can use like this:

aria2c --max-concurrent-downloads 4 --split 4 --max-connection-per-server 16 -i urls.txt

Courtenay