Re: SMTP Virtual Server: How do I make the source port stop using a random port?

From: Alun Jones (alun@texis.com)
Date: 02/20/03

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    From: alun@texis.com (Alun Jones)
Date: Thu, 20 Feb 2003 21:59:35 GMT

    In article <017101c2d927$1bfa84f0$a501280a@phx.gbl>, "mike beste"
    <mbeste@fulcrum.net> wrote:
    >SMTP Virtual Server: How do I make the source port stop
    >using a random port?

    _If_ you were to make the source port be a fixed port, the result would be
    that you could not connect several times over a short period of time. A
    five-tuple of source address, source port, protocol, destination port and
    destination address may not be re-used within 2*MSL (essentially, four
    minutes) of its last use. So, since (as you've pointed out) the destination
    port is always 25, the destination address is fixed at the IP address of your
    target mail server, the source address is your IP address, and the protocol is
    "TCP", the only thing that prevents one socket from being a reuse of the
    five-tuple from a previous socket is the source port. That is why the source
    port _must_ vary.

    Alun.
    ~~~~

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