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    How many connections will a FTP data port support?


    Hi there,
    We have been restricted a small number of data ports for FTPs usage. I am therefore wondering how many client connections will be each data port support? Given command port (21) must support many, I'm assuming the same applies to each data port?

    Thanks
    Last edited by beene; October 3rd, 2010 at 11:37 PM. Reason: spelling error
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    Each port can support one client. Port 21 doesn't support many connections, it merely seems that way because everyone connects to port 21. However, after connecting they are immediately transferred to a higher port for one-on-one communication with the server. The reason they are transferred to a higher port is to free up the port so other people can initiate connections.

    Note that from a technical perspective you could modify your FTP server software to serve multiple users through the same data port, however this would result in terrible service. FTP by nature involves long burst transfers and you would run into all sorts of conflicts and connection drops if you tried to run multiple clients off a single data port.
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    Thanks for the reply, its been somewhat difficult to obtain this info. So if 1 data port = 1 client, and I was constraint (for security on the firewall) to 10 passive ports, I could only have a max of 10 clients at one time, would this be correct?

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