[e2e] [Fwd: Re: [Fwd: Re: What if there were no well known numbers?]]

Dave Crocker dhc2 at dcrocker.net
Sat Aug 5 08:29:05 PDT 2006

I decided to check with my next-door neighbor from that period...


-------- Original Message --------
Subject: Re: [Fwd: Re: [e2e] What if there were no well known numbers?]
Date: Sat, 5 Aug 2006 11:06:58 -0400
From: Steve Crocker <steve at shinkuro.com>
To: Dave Crocker <dhc2 at dcrocker.net>

The concept of well known ports appeared early in the network
evolution.  The original thought -- at least it was my thinking --
was there would be known port numbers for specific services, just as
there is today, and that the server side would then deal off the
connection to another port, thereby freeing the port for another
connection.  Thus, if we're talking about Telnet, there would be a
standard Telnet port and each client who wanted to connect to that
host would initiate a connection to the Telnet port.  The server host
would accept one of those connections and then move it to another
port on either the same or a different host.  The reconnection part
of this design was forcibly killed on August 5, 1970 -- exactly 36
years ago today! -- in an extraordinary phone call from Barry Wessler
to me because of push back from the community that bubbled up to him
at ARPA.  That left a hole in the design which was eventually filled
by ICP.

Ignoring the politics and specific design, the concept of a well
known port was, I believe, a simple and obvious idea that was
generally accepted as part of the initial framework.  I don't think
there was any great discussion or controversy, so there probably
wasn't much written about it.

Even when you bring DNS into the picture, although one could argue
that each host could establish its own choice of ports for various
services, e.g. host foo.xx could choose port 897 for http service
instead of port 80 and use a resource record in DNS to advertise this
fact, the DNS service itself would still need a standard port
number.  (Well, I suppose you could include the port number along
with the address in the A records corresponding to NS records or have
a service record accompany the A record, but there would still need
to be a well known port for DNS service at the root servers or,
perhaps, the distribution of their port numbers as part of the hints
file and priming response.)

Does this help?  Does this matter?


Steve Crocker
steve at shinkuro.com

Try Shinkuro's collaboration technology.  Visit www.shinkuro.com.  I
am steve!shinkuro.com.

On Aug 5, 2006, at 10:50 AM, Dave Crocker wrote:

> This is from a long thread on the End to End discussion list.  As I  
> recall, NCP
> didn't have "well known ports" but rather had an Initial Connection  
> Protocol
> that chose connection 'ports' dynamically.  So the only 'well known  
> port' was
> for ICP.
> d/
> -------- Original Message --------
> Subject: Re: [e2e] What if there were no well known numbers?
> Date: Fri,  4 Aug 2006 16:08:56 -0400 (EDT)
> From: jnc at mercury.lcs.mit.edu (Noel Chiappa)
> To: end2end-interest at postel.org
> CC: jnc at mercury.lcs.mit.edu
>> From: Bob Braden <braden at ISI.EDU>
>> At 10:39 PM 8/2/2006 -0400, David P. Reed wrote:
>>> The concept of "well-known ports" was built for a world in which  
>>> there
>>> was no lookup function, no DNS - in fact for a world where people
>>> typed addresses in octal, long before there was a naming service  
>>> (even
>>> before the hosts file).
>> Well, not exactly. It was (deliberately) built for a world in  
>> which we
>> did not want increased communication fragility resulting from DNS
>> lookup failures.
> Does it have to be one (no infrastructure) or the other  
> (fragility)? I always
> thought it was some of both.
> In any event, I got the impression that TCP pretty much just  
> followed NCP's
> lead on this. Is there anyone here who was around for the NCP  
> design who can
> comment on what NCP's reasons were for well-known ports? My guess  
> would be
> lack of infrastructure (as DPR points out, that was before there  
> was even
> 	Noel
> -- 
>   Dave Crocker
>   Brandenburg InternetWorking
>   bbiw.net


  Dave Crocker
  Brandenburg InternetWorking

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