how to configure DHCP relay with ISC.

Simon Hobson dhcp1 at
Thu Apr 15 11:45:31 UTC 2010

Guo, Fei wrote:

>   can you give me an example about how to configure on the 
>client/relay/server side, I have installed 4.1.1 version, a 
>simple topology is the following:
>   client ------------------------------------------  relay 
>------------------------------------------ server
>        eth1                     
>   I want get a IP address on client "eth1", it should be in net 
>"192.168.1.x/24". thank you very much.

Client: you don't need to do anything, the default install should work.
Server: You don't have to do anything special, just define the subnet 
and an appropriate range and options.

Relay agent: Not sure about that (I haven't used it myself) - you'll 
have to read the man pages unless someone else pops up to answer.

A bit more abut the server config. For technical reasons, you must 
define the subnet that the server is in (even if it's empty), so 
you'll have something like :

<global options>
subnet ... {
   <subnet options>
   range 192.168.1.x 192.168.1.y ;
subnet ... {

The assignment of clients to subnet is automagic - the relay agent 
adds information to the packets that the server can use to identify 
the client subnet, the rest "just happens".

Simon Hobson

Visit for books by acclaimed
author Gladys Hobson. Novels - poetry - short stories - ideal as
Christmas stocking fillers. Some available as e-books.

More information about the dhcp-users mailing list