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Re: [OCLUG-Tech] Re TCP Ports -- and the little guy listening

  • Subject: Re: [OCLUG-Tech] Re TCP Ports -- and the little guy listening
  • From: Adrian Irving-Beer <wisq-oclug [ at ] wisq [ dot ] net>
  • Date: Wed, 27 Jul 2005 17:16:35 -0400
On Wed, Jul 27, 2005 at 04:19:20PM -0400, William Case wrote:

> Somehow I had got it fixed in my head that a TCP port was something
> physical as are a serial or parallel port.
> All the "listening" metaphors now make sense.

Right.  In terms of listening, ports are simply a means of determining
what service you're asking for.  Said service listens on that port.

Once connections are established, they're tracked independently.  It's
the combination of source address, source port, target address, and
target port that defines a TCP connection.

That's why an HTTP server can have hundreds of requests coming in at
once, all with a destination port of 80, and yet still keep track of
them all.  If each port had a single buffer, things would get messed
up pretty fast. :)

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