Change DHCP-Server Address

[glenn.satchell at uniq.com.au]

On 2021-06-28 16:31, Bernd Nachtigall wrote:
> Hi,
> 
> there is a DHCP-Service which is configured to use a secondary
> IP-Address. This runs fine.
> 
> Main IP: 10.12.251.12
> Sec. IP: 10.12.251.111
> 
> But when check the answers from the service at a client it seems that 
> the
> service use the main IP as sender. Is there a way to configure the 
> dhcpd
> that it uses the sec. IP-Addr. as 'from' when answering to clients?
> 
> Bernd

Hi Bernd

Looks like you need to use the server-identifier statement. This is from 
the dhcpd.conf man page:

The server-identifier statement

server-identifier hostname;

The server-identifier statement can be used to define the value that is 
sent in the DHCP Server Identifier option for a given scope.  The value 
specified must be an IP address  for  the  DHCP server, and must be 
reachable by all clients served by a particular scope.

The  use  of  the  server-identifier  statement is not recommended - the 
only reason to use it is to force a value other than the default value 
to be sent on occasions where the default value would be incorrect.  The 
default value is the first IP address associated with the physical 
network interface on which the request arrived.

The usual case where the server-identifier statement needs to be sent is 
when a physical interface has more than one IP address, and the one 
being sent by default isn't appropriate  for  some or  all  clients  
served  by that interface.  Another common case is when an alias is 
defined for the purpose of having a consistent IP address for the DHCP 
server, and it is desired that the clients use this IP address when 
contacting the server.

Supplying a value for the dhcp-server-identifier option is equivalent to 
using the server-identifier statement.

regards,
Glenn