How does that tcp traffic work

[Bliss, Aaron]

I know this is a bit of a networking question more than a redhat
question, however I'm sure you guys will be able to explain this to me;
I'm trying to understand exactly how this works, and have not been able
to find any solid authority on the subject; I understand the concept of
ports, well know ports, and part of the initial 3 way handshake of a new
tcp session; My question is, does the initial receiving host of a
session (usually a server) use the port that it's listening for the tcp
session, or does it negotiate a port number that is not in use like the
client does?  For example, host A is a client, host B is a webserver
listening on port 80; host A wants some data from host B's port 80; lets
say host A wants to use port 6785; will the tcp session then use port
6785 for host A and port 80 for host B, or will they also pick an
available port from host B as well; if port 80 is used, how are multiple
sessions possible; i.e. how can the host B serve up more web traffic if
port 80 is busy?  Thanks for your help.

Aaron

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