support for User Class options

Jeffrey Hutzelman jhutz at
Fri Jan 11 01:52:42 UTC 2008

--On Thursday, January 10, 2008 03:54:41 PM -0500 Reid Vail 
<rsv869 at> wrote:

> Hi Brian -
> I just saw a few minutes ago.  And that's good news.  So far so good.
> We use User Class this way:  User Classes can have Options associated
> with them.  Assuming I were a user and I get a User Class assignment
> called Allow, then the Allow options would include a correct subnet
> mask, the right default gateway, the right DNS settings, etc.  If the
> User Class is Deny, then give a 32-bit mask, remove the default gateway,
> change the DNS,etc.  It's these User Class options, and how they are
> set, that I wonder about.

That sounds like some vendor's marketing name for the ability to send 
different options to different clients based on the client's MAC address or 
information in the request.  This is fairly basic functionality, and the 
ISC server supports it in several ways, including allowing specific options 
for each host, placing host declarations into groups with options that 
apply to an entire group, and through the use of classes matching requests 
which meet particular conditions.

None of this is really related to option 77, which is about a client being 
able to say something like "I am in marketing" and getting a different 
printer than a client who says "I am in tech support".  For more on this 
option, see RFC3004.

-- Jeffrey T. Hutzelman (N3NHS) <jhutz+ at>
   Carnegie Mellon University - Pittsburgh, PA

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