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

William Case wrote:

I need some help understanding how network or TCP ports work.

I am particularly confused by the concept that something is "listening"
on certain ports.  I hope there isn't a little guy in my computer with
big ears, because he is probably dead by now.  I haven't been feeding

Here is what I think I understand from various manuals.

If someone wants to send me an email, their 'sendmail' calls on various
functions?? from a library?? that adds an IP and a TCP header that

It helps when you realize that TCP is really a "transportation" and mail is at another layer.

Rough Idea.

You Send an email.

Send mail goes out on the net. and finds out what system has the MX duties for your domain (Rogers.com in this case)

It then starts a TCP connection, and goes thru the SMTP "ritual" to say that it wants to send an e-mail. The SMTP server records the mail as it is received, and perhaps forwards it to the mail spool where it will wait for you to also make an TCP connection and retrieve it to your local storage.

Charles MacDonald      cmacd [ at ] TelecomOttawa [ dot ] net     Stittsville Ontario
1800+ Canadians oppose Bill C-60 which protects antiquated Recording,
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