Website accessed from multiple ports by the same pc?

Discussion in 'Application Software' started by Stannieman, Sep 20, 2014.

  1. Stannieman

    Stannieman MDL Guru

    Sep 4, 2009
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    Hi,

    The situation is as follows:
    I want to run a database that has some data about the members of our club. Our club is behind a nat that we have no control over, so I can't really see how things are set up.
    I've now chosen 1 particular ethernet socket that I want to connect the server with.
    So it's like this:
    external ip -> nat out of control (might be 2 or 3 routers even) -> chosen ethernet socket.

    Now I wanted to know what port of the external ip my traffic should go to so it gets to my wall socket.
    I set up a web server at my home, connected a pc to the socket of choice and made a quick browse + a few ctrl F5s while my server had wireshark running.

    Weird thing is that not all my http traffic goes through the same port of the external ip.
    With the first browse the http get and text stuff goes from/to externalIp:43158, after waiting a few seconds and refreshing it goes over 43682.

    Is this normal behaviour?
    Now I know there's some "Fortiweb" or "Fortiguard" software running somewhere in the out if control zone to disable torrent and some "illegal sites". Could it perhaps be that it randomly changes ports sometimes to make it impossible to run a server like I want to?
     
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  2. Stannieman

    Stannieman MDL Guru

    Sep 4, 2009
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    #3 Stannieman, Sep 21, 2014
    Last edited: Sep 21, 2014
    (OP)
    I think I confused you with the website story, that was just for testing.
    The thing is that normally I should be able to talk to port x of the external ip and I end up at port y of the pc in the ethernet socket. The port y doesn't matter cause the server will have only 1 thing running so I can set that to listen to y without causing any conflicts.
    Now it seems that when the machine inside the club talks to a server in the outer world (connection is opened from behind the nat) the traffic can go through multiple ports of the external IP. So it looks like some server in the nat just opens a random port for every tcp connection that's made from behind it. Once that connection is closed the port closes and for every new "web action" you do from behind the nat the server inside the nat picks a random port to let that connection go through. This way you can't establish a connection from the outer world to the club pc because there's no port that redirects to that pc, because the connection isn't opened from behind the nat. That would explain that a different source port of the external ip is used when visiting a website twice without changing any config.
    The question is if that makes sense and if it's possible.

    EDIT: I'm going to talk to the IT guy anyway cause I'll probably also install a wamp server on the database pc, so I need 2 ports and that does require some forwarding that isn't already done.

    +++PARTIALLY DRUNK POST+++

    EDIT2: Never mind guys! I'm officially a retard... It's pretty normal that it uses random ports when it is never set otherwise. Thread can be locked.
     
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