Wireshark-dev: Re: [Wireshark-dev] How to avoid dissection based on port defined by a different
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From: Jeff Morriss <jeff.morriss.ws@xxxxxxxxx>
Date: Thu, 16 Dec 2010 14:41:53 -0500
Guy Harris wrote:


On Dec 15, 2010, at 8:26 PM, Chris Maynard wrote:


Guy Harris <guy@...> writes:
SHOULD in some RFC - or even a MUST - but I don't know offhand what RFC that is) 

http://tools.ietf.org/html/rfc2119
Sorry, I didn't make it clear that "what RFC that is" is "what RFC - if any - says that ephemeral ports should be handed out by default", not "what RFC explains what SHOULD and MUST mean". *Is* there an RFC that describes well-known, registered, and ephemeral ports? The first two of them are mentioned in the IANA port number assignment list: 

http://www.iana.org/assignments/port-numbers

but that doesn't mention ephemeral ports.
There's been a lot of discussion about port assignment/registration on the IETF tsvwg mailing list of late. There's a draft floating around which describes the port number ranges in section 6: 

http://tools.ietf.org/html/draft-ietf-tsvwg-iana-ports-09#section-6

and then goes on to say, in section 8.1.1:


   o  Ports in the Dynamic Ports range (49152-65535) have been
      specifically set aside for local and dynamic use and cannot be
      assigned through IANA.  Application software may simply use any
      dynamic port that is available on the local host, without any sort
      of assignment.  On the other hand, application software MUST NOT
      assume that a specific port number in the Dynamic Ports range will
      always be available for communication at all times, and a port
      number in that range hence MUST NOT be used as a service
      identifier.