Re: Guidance needed on well known ports

Re: Guidance needed on well known portsTwo points here.

First, I totally agree with Phillip that closing the registry is the right 
direction to head. It would be lovely if this became a consideration in new 
protocol work at the IETF. I'm not sure how quickly we can actually close it, 
but having a chosen and stated direction that points somewhere else seems very 
appropriate for new protocol work. Please note how long it is taking to kill 
the classful addressing terminology. If you want to change directions on port 
number interpretation, please start soon..

Second, as long as the current mechanism is "widely used" (and, with the rise 
of HTTP-as-transport and port-agile protocols, it's less widely used every day 
anyway), people try to use the current mechanism to understand and characterize 
traffic on their networks (you may laugh, and it is getting funnier every day, 
but they do exactly this with firewall rules, protocol analyzers - and the good 
ones DON'T use port numbers much any more - and traffic monitors).

The definition of an application port is what the two ends of the application 
think it is. If I think that port 25 is a good port, you do, too, and we never 
use it for anything else, why is this wrong? It seems to me that saying, "if 
you want to understand what the traffic on this network looks like, our 
direction is that you'll need to check SRV records most of the time in the 
future" seems to give people who do firewalls, traffic monitors, etc. the right 
signal as well.

Thanks,

Spencer
  ----- Original Message ----- 
  From: Hallam-Baker, Phillip 
  To: Stephane Bortzmeyer 
  Cc: ietf(_at_)ietf(_dot_)org 
  Sent: Monday, March 20, 2006 6:13 AM
  Subject: Re: Guidance needed on well known ports


  Refusing new registrations is what I meant by closing the registry.

  Of course it is not possible to change the way deployed systems work 
retrospectively.

  The question was about a new protocol.

  We are about to see several thousand new web services protocols being 
developed per year. A port each would be idiotic. Expecting UDDI deployment is 
at this point futile.

  The solution that people are going to turn to is to use the existing dns as 
deployed. Fortunately windows 2k uses srv extensively.

  We should also promote the use of srv for existing protocols for 
configuration. _pop3._tcp.example.com can only advertise the location of the 
pop server. Why not use it and save me debugging mail config for friends and 
familly?


   -----Original Message-----
  From:   Stephane Bortzmeyer [mailto:bortzmeyer(_at_)nic(_dot_)fr]
  Sent:   Mon Mar 20 03:06:23 2006
  To:     Hallam-Baker, Phillip
  Cc:     ietf(_at_)ietf(_dot_)org
  Subject:        Re: Guidance needed on well known ports

  On Sat, Mar 18, 2006 at 02:09:47PM -0800,
   Hallam-Baker, Phillip <pbaker(_at_)verisign(_dot_)com> wrote
   a message of 163 lines which said:

  > The Internet has a signalling layer, the DNS. Applications should
  > use it.  The SRV record provides an infinitely extensible mechanism
  > for advertising ports.

  I agree here but this means we should keep at least one well-known
  port, 53.

  > IANA should be told to close the well known ports
  > registry. Applications should use DNS SRV records for service
  > location.

  I agree with that rule for the *future* protocols. But it does not
  help with current (and widely deployed) protocols. So, asking IANA to
  refuse new registrations in the well-known ports registry is one
  thing, shutting down the registry is another.





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