dhcpd and dhcrelay

[Elena Timoshkina]

Thanks.

Tuesday, September 30, 2008, 9:02:24 PM, you wrote:

> On Tue, Sep 30, 2008 at 03:56:38PM +0400, Elena Timoshkina wrote:
>> Hi,
>> I have a problem to solve.  I have a dhcpd server and now I need a
>> dhcprelay on the same server.

> Why?  Where will you be relaying packets from/to if the packets are 
> arriving at the dhcpd server already?
Dhcrelay will work with other dhcpd server (
dhcrelay_servers="10.97.5.2" ).

>> Dhcpd in vlan39 interface. I binded Dhcpd in vlan39 to
>> add to dhcpd.conf file:
>>        local-address 10.1.1.254;

> Did you start dhcpd daemon with the "vlan39" parameter so it only 
> listens on that one interface?  This is a separate requirement from 
> using local-address.
Yes.
# ps -auxww|grep dhcpd
 /usr/local/sbin/dhcpd -q -cf /usr/local/etc/dhcpd/dhcpd.conf -lf /var/db/dhcpd/dhcpd.leases -pf /var/run/dhcpd/dhcpd.pid -user dhcpd -group dhcpd -chroot /var/db/dhcpd vlan39


>> Dhcrelay in vlan667 interface.
>> grep dhcrelay /etc/rc.conf  :
>>  dhcrelay_enable="YES"
>>  dhcrelay_servers="10.97.5.2"         # dhcrelay server(s)
>>  dhcrelay_ifaces="vlan667"  

> It makes no sense to run dhcrelay with a single interface.  You need 
> two interfaces that dhcrelay will relay the packets between.
How can I determine two interfaces for dhcrelay? It will work in
vlan667 (requests) and vlan667 (relay to server  10.97.5.2).
It is possible?

>>  Dhcpd works fine.
>>  
>> When I try to run dhcrelay :
>> /usr/local/etc/rc.d/isc-dhcrelay start
>> Starting dhcrelay.
>> Internet Systems Consortium DHCP Relay Agent V3.0.5
>> Copyright 2004-2006 Internet Systems Consortium.
>> All rights reserved.
>> For info, please visit http://www.isc.org/sw/dhcp/
>> Listening on BPF/vlan667/00:08:02:f0:25:81
>> Sending on   BPF/vlan667/00:08:02:f0:25:81
>> Sending on   Socket/fallback
>> 
>> Dhcrelay starts. But  sockstat tells me:
>> 
>> root     dhcrelay   69409 4  udp4   *:67                  *:*
>> dhcpd    dhcpd      68725 5  udp4   10.1.1.254:67     *:*
>> 
>> Dhcpd binded in address 10.1.1.254
>> But dhcrelay not binded in interface vlan667. How can I do it - to
>> bind dhcrelay in address 10.97.7.18 only?

> dhcrelay doesn't bind to IP addresses, but rather physical interfaces.
ok. how to bind it in vlan667 and not bind in vlan39 ?
> This is because the DHCP protocol needs to handle broadcasts from 
> unaddressed hosts (0.0.0.0 source address) and send to all-ones 
> broadcast 255.255.255.255.
yes, can dhcrelay listen only broadcasts in vlan667 (not vlan39 and
others)?

Thanks.


-- 
Best regards, 
Elena Timoshkina