host-identifier and option 82

[Michal Vančo]

Hi Glen,

yes I know about stash-agent-options flag. And I also know what its purpose is.
Despite this fact, what happens when you restart DHCP server? What I know is, that no information about
static leases (static host entries) is written into lease file. Hence server will forget all stashed agent options
and the client will not be able to renew its address. This is what I probably see when my
logfile starts to fill with "unknown lease" messages after I restart server.

regards
-michal

On 27.1.2012, at 3:53, Glenn Satchell wrote:

> Hi Michal
> 
> There is a dhcp server configuration option to cover this very case, from
> the dhcpd.conf man page:
> 
>          stash-agent-options flag;
> 
>          If the stash-agent-options  parameter  is  true  for  a
>          given  client,  the  server will record the relay agent
>          information options sent during  the  client's  initial
>          DHCPREQUEST  message when the client was in the SELECT-
>          ING state and behave as if those options  are  included
>          in  all  subsequent  DHCPREQUEST  messages  sent in the
>          RENEWING state.   This  works  around  a  problem  with
>          relay  agent  information  options,  which is that they
>          usually not appear in DHCPREQUEST messages sent by  the
>          client in the RENEWING state, because such messages are
>          unicast directly to the server and not sent  through  a
>          relay agent.
> 
> regards,
> -glenn
> 
>> Hi,
>> 
>> I've just tried to use host-identifier to assign static IPv4 address based
>> on option 82 agent.remote-id like this:
>> 
>> host hostname {
>> host-identifier option agent.remote-id XX:XX:XX:XX:XX:XX;
>> fixed-address aaa.aaa.aaa.aaa;
>> }
>> 
>> this apparently works until client renews its IP address. DHCPREQUEST is
>> going directly from client to server bypassing relay agent which means
>> that there is no option 82 inserted when client is trying to renew
>> address. So server is unable to match DHCPREQUEST against host
>> declaration. Am I right in this? Is there any workaround? Any clue?
>> 
>> thanks
>> michal
>> 
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>> dhcp-users at lists.isc.org
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>> 
> 
> 
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