Disabling "option 82" processing in ISC DHCP server.

Glenn Satchell Glenn.Satchell at uniq.com.au
Wed Oct 14 14:40:57 UTC 2009

>From: "Sivaraman, Radhakrishnan" <radhakrishnan.s at hp.com>
> Hello all,
> I have 2 queries.
> 1)     How to disable the processing of "option 82 (Relay Agent
> Information option)" in ISC DHCP server? I need this to ensure that
> DHCP server will not echo the relay agent information in its reply.

The relay agent strips the option 82 information before transmitting
the packet back to the client. This behaviour is part of the RFC. What
are you trying to achieve by doing this?

Probably the simplest way is to assign a null value, eg

	option agent.remote-id "";

Note that I haven't tested this, and it may break the way the relay

> 2)     How to configure default gateway? Is it via "option routers
> <addr>" ?

Yes, that is correct. Usually you will have an option routers
statement in every subnet as the default router is different.
There is an example configuration in the dhcpd.conf man page.

Al options are described in the dhcp-options man page

     option routers ip-address [, ip-address... ];

       The routers option specifies a list of  IP  addresses  for
       routers  on the client's subnet.  Routers should be listed
       in order of preference.

Glenn Satchell   mailto:glenn.satchell at uniq.com.au | Miss 9: What do you
Uniq Advances Pty Ltd       http://www.uniq.com.au | do at work Dad?
PO Box 70 Paddington NSW Australia 2021            | Miss 6: He just
tel:0409-458-580     fax:02-9380-6416              | types random stuff.

> Thanks in advance,
> Radhakrishnan S

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