How to configure source IP in answer to relayed DHCP requests.

[Morten Laursen]

Thanks, but it does not work. According to the man page it is used to set the IP address used in a DHCP option field.
It does not change the source address used to send the IP packet.

Any other ideas?

Venlig Hilsen / Regards 
Morten

-- 
Morten Laursen, M.Sc.S.E.
RTX Telecom A/S - http://www.rtx.dk/
Direct phone: (+45) 96 32 24 03


> -----Original Message-----
> From: dhcp-users-bounce at isc.org [mailto:dhcp-users-bounce at isc.org]On
> Behalf Of VKR V
> Sent: 14. december 2006 19:23
> To: dhcp-users at isc.org
> Subject: Re: How to configure source IP in answer to relayed DHCP
> requests.
> 
> 
> server-identifier 
> <specify_the_IP_you_want_clients_to_identify_DHCP_server>;
> 
> 
> Morten Laursen <MLA at rtx.dk> wrote:  Hi,
> 
> As the subject indicates, I have a bit of a complex setup:
> 
> network A <-> [router] <-> network B <-> [DHCP server] <-> network C
> 
> My DHCP server has 2 interfaces (one connected to the 
> internet and one private) for which it serves DHCP addresses. 
> I run dhpcd 3.0.4
> 
> From my normal wokring network (not on the sketch) I have 
> access to both the machine's interfaces, so to get that to to 
> work I have configured source based routing, so it answers on 
> network B or C depending on the sender address, i.e. it 
> answer on the network where it got the reply. That works fine.
> 
> My problem is that the devices on network A uses the DHCP 
> server via DHCP relay in the router. When dhcpd receives the 
> requests from the router it replies with the IP address 
> belonging to network C, so the reply is sent to network C and 
> is never received by the client.
> 
> So the question is how can I configure either 
> a) that dhcpd always uses a specified IP address as source IP 
> in replies to relayed DHCP requests or even better
> b) that dhcpd uses the source address where it received the 
> request for the reply.
> 
> (I guess the problem arises because the relayed DHCP requests 
> from the router uses the routers network A address as source, 
> so dhcpd cannot from the packet's IP address determine which 
> interface to use)
> 
> 
> Any ideas would be appreciated.
> 
> 
> Venlig Hilsen / Regards 
> Morten
> 
> -- 
> Morten Laursen, M.Sc.S.E.
> RTX Telecom A/S - http://www.rtx.dk/
> Direct phone: (+45) 96 32 24 03
> 
> 
> 
> 
>  
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