ietf-nntp MODE READER

[Russell Vincent]

On Wed, Jul 26, 2000 at 05:55:05PM +0100, Clive D.W. Feather wrote:

> Again, what's the effect - for the client - of those flags being set or
> clear ? What changes ?

Without trying to be condescending (everyone on this list probably
knows the first part of this), but trying to be thorough ...

In most news server software I know of, there are 2 main states:

 - feeding: client has access to transfer news to us in a format
   that almost no modification/checking is done (ignoring spam
   filtering for now). This is usually limited to specific trusted
   machines, usually accomplished with some kind of mutual agreement.

 - reading: client has access to retrieve news and 'post' news. News
   received from the client is usually checked more thoroughly and
   often specific headers added - usually identifying the client
   to this specific server. This is usually the injection point into
   the Usenet network.

The client usually only has access to one of the above states. There
are cases where the client may need access to both states and this
is where the 'MODE READER' command probably originated and is used
to switch from a feed state (which would be default) to a reading state.

For Diablo, executing 'MODE READER' (assuming the client currently
has authenticated and has feed access) does the following:

 - Disables access to IHAVE and the streaming extensions not mentioned
   in this draft (CHECK/TAKETHIS), which are used for feeding.

 - Enables access to POST, GROUP, LAST, NEXT, LIST, LISTGROUP, NEWSGROUPS,
   STAT and the 'x' commands (XOVER, etc) which apply to a reading client
   only.

If the client already has access to the reading client commands, then
MODE READER is a nop and the 200/201 greeting banner is sent.

At no time does the client have access to the entire command set. It
will either start with only the reading commands or the feeding
commands. The client also cannot switch from a reading state to
a feeding state.

I believe INN is quite similar to the above.

For Diablo, the authenticated client (feeding or reading) always has
access to some of the commands like ARTICLE, HEAD, BODY. This probably
isn't the case in other news server software.

 -Russell