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Purpose of Port 0.

Danny Niu <dannyniu@hotmail.com> Mon, 20 February 2017 08:31 UTC

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From: Danny Niu <dannyniu@hotmail.com>
To: "ietf@ietf.org" <ietf@ietf.org>
Subject: Purpose of Port 0.
Thread-Topic: Purpose of Port 0.
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Date: Mon, 20 Feb 2017 08:30:45 +0000
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Hi, all. 

Recently on the POSIX mailing list, there's a discussion on the correct way to bind to (or listen on) an ephemeral port. While I referenced the "UNIX Network Programming", we're not quite satisfied because even though it's co-written by someone involved in IETF, it's still JUST a textbook. 

The canonical way to do this, according to some (from stackoverflow.com, and other places), is to bind to port 0, which I assume had been reserved for this purpose, but I haven't find anything to back this up yet. 

On the POSIX list, they suggested that IETF should, (or should have already) state(d) that port 0 be reserved for binding to ephemeral ports. So can we find any reference for this? Or should we draft an RFC? 

Thanks.

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