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Dynamically change the TCP port of the client and server

  • Is this type of communication possible using QT?

  • Lifetime Qt Champion

    Hi and welcome to devnet,

    Usually ports are not dynamically changed, new connections are created and then used.

    Can you give more context on your use case ?

  • @SGaist This is a protocol from an old machine for which there is no documentation. I only have the Wireshark log. The closest I found was maybe Indy protocol. Specifically IdSimpleServer?

  • Lifetime Qt Champion

    You will have to inspect the content of the messages exchanged. They will likely provide more information about what is done that requires these ports change. Or it might just be several different protocols communicating between the two machines.

  • Lifetime Qt Champion

    as the different Seq/Ack counters indicate, these are two independent TCP connections. More capturing is needed to see the Syn/Ack/Ack Startup sequences.


  • This is complete Wireshark log file.

  • @bygsbunny It may be the complete file but it cannot be the complete transaction summary for the connections in question. I'd suggest that there is some filtering going on so the log is incomplete.

    And by incomplete I mean your OP wireshark dump. I don't do online filesharing sites so I have no idea what is in the log link you posted.

    What I see in your OP is fragments of TWO distinct TCP sessions.

  • Based on the analysis of wireshark capture it seems that there exists multiple TCP/IP connection between the machine having IP's "" and ""
    eg: <--------> <-------->

    As mentioned in the snapshot of the application it looks like machine having IP{server} is having binding port range from [10000 - 10100]

    Is this type of communication possible using QT?

    @bygsbunny Answer to your question is yes, it's possible to do this type of communication in QT.

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