DHCP Relay

[Glenn Satchell]

>Date: Tue, 28 Apr 2009 13:17:36 +0300
>From: William Jobs <wllmjbs at gmail.com>
>
> I'd also appreciate it if someone could let me know, if I'm attempting
> something that is just not possible. That way I could stop banging my head
> against the wall :)
> 
> 
> On Tue, Apr 28, 2009 at 12:49 PM, William Jobs <wllmjbs at gmail.com> wrote:
> 
> > Hi all,
> >
> > I've been trying out ISC's dhcp software as a relay server and everything
> > is working fine except for the remote-id sub-option of Option 82. For some
> > reason dhcrelay will not include this sub-option in the packets it forwards
> > to the DHCP server. I get the circuit-id sub-option, just fine.
> >
> > Is there a specific way to enable this feature? I'm currently running
> > dhcrelay as follows for debugging purposes:
> >
> >         dhcrelay -d -a 10.0.0.1
> >
> > Any help would be appreciated.
> >
> > Thanks.


Which version of dhcrelay and dhcpd are you using? What platform? (linux, *bsd, 
solaris, hp and so on...)

This is from the 4.1.1b1 dhcrelay man page, note the last sentence.

     -a   Append an agent option field  to  each  request  before
          forwarding  it  to the server.   Agent option fields in
          responses sent from servers to clients will be stripped
          before  forwarding  such  responses back to the client.
          The agent option field will contain two agent  options:
          the  Circuit  ID suboption and the Remote ID suboption.
          Currently, the Circuit ID will be the printable name of
          the interface on which the client request was received.
          The client supports inclusion of a Remote ID  suboption
          as well, but this is not used by default.

This is the equivalent section from the 3.1.1 dhcrelay man page.

     If the -a flag is set the relay agent will append  an  agent
     option  field  to  each  request before forwarding it to the
     server.   Agent option fields in responses sent from servers
     to clients will be stripped before forwarding such responses
     back to the client.

     The agent option field will contain two agent  options:  the
     Circuit   ID   suboption   and   the  Remote  ID  suboption.
     Currently, the Circuit ID will be the printable name of  the
     interface  on  which  the  client request was received.  The
     client supports inclusion of a Remote ID suboption as  well,
     but this is not used by default.

So it seems the remote-id is not added by default. The remote-id is
mentioned in the source, but there is no way to set it. Looks like if
the packet arrives with a remote-id then the remote-id will not be
removed.

Sorry it's not much use to you...

regards,
-glenn