[NNTP] LIST EXTENSIONS (again)

Kai Henningsen kaih at khms.westfalen.de
Sun Nov 14 06:36:00 PST 2004


rra at stanford.edu (Russ Allbery)  wrote on 08.11.04 in <87lldbncep.fsf at windlord.stanford.edu>:

> What would you think of documenting port 433 for transit connections in
> the standard and saying that transit feeds SHOULD use port 433 instead of
> port 119?  That to me seems like the most viable way of eliminating MODE
> READER.

Something like the following:

* Document that 433 is the standard port for transfer
* Document that for historical reasons, very many servers use 119 just as
  for client access
* Document that some few servers use both client and transfer access on
  port 119, and that this case is SHOULD NOT, and that there's an old
  mechanism of "MODE READER" for coping with this, and that, *if* that is
  needed, that command needs to be the very first thing sent, and if the
  server doesn't like that command in that position, not send it at all.
* And document that standard servers might, to be compatible with
  pre-standard clients, want to support MODE READER on port 119 as a no-op
  compatibility command - they ought to accept it whenever any client
  command is allowed, for maximum compatibility.

* Modify INN to be able to have innd simultaneously listen on 119 and 433
  for migration purposes, with MODE READER not working on 433. Also make
  433 the default transfer port for new installs.

Open question: what should a modern INN in migration configuration do, and  
should that be documented - that is, a server that supports LIST  
EXTENSIONS but does have a combined transit/reader port while it hasn't  
yet mirated all transfer connections off to 433?

Possibly document a MODE_READER extension that asks for MODE READER and is  
documented purely for that case, with SHOULD NOT and so forth? Ok, let's  
spell that out:

# MODE_READER means if you want reader access, your very next move MUST be
  to issue MODE READER and reset everything you know. You really cannot
  have TLS running for that.

# Servers SHOULD NOT use this extension. It SHOULD NOT be used except
  while migrating existing transfer peers to 433.

# Pre-NNTPv2 Servers may need that functionality, or not (see above).

# It only ever affects port 119, never port 433.



Just to make sure to avoid confusion: this is port 433 "nnsp", not port  
563 "nntps" or "snntp" (NNTP over SSL) which ought to die.

>From port-numbers:

nntp            119/tcp    Network News Transfer Protocol
nntp            119/udp    Network News Transfer Protocol
#                          Phil Lapsley <phil at UCBARPA.BERKELEY.EDU>

nnsp            433/tcp    NNSP
nnsp            433/udp    NNSP
#                          Rob Robertson <rob at gangrene.berkeley.edu>

nntps           563/tcp    nntp protocol over TLS/SSL (was snntp)
nntps           563/udp    nntp protocol over TLS/SSL (was snntp)
#                          Kipp E.B. Hickman <kipp at netscape.com>


MfG Kai



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