Peter Eisenman wrote:
> Assume we look an a certain port say, port number 1234.
>
> Are there TWO different ports 1234 - one for the outgoing direction and one for the incoming?
> Or is there only one port which can be used only in one direction at a certain time: either
> as incoming or outgoing?
>
> If the ladder would be true then an already established incoming connection on port 1234 would block
> any outgoing connection on the same port.
>
> Peter

Just the one.

But your last comment may be misleading. Just because something's using
port 1234 at /my/ end doesn't mean I can't connect to someone else's
port 1234. A tcp connection is defined by two ip addresses and two
ports; a port on a server has to be known as it defines which program
you're connecting to. A port on a client is (usually) picked by the
system from a pool of free numbers; you don't generally have to worry
about it.

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