[Dnsmasq-discuss] Different bootp options to different MACs on same net

Simon Kelley simon at thekelleys.org.uk
Sat Jul 29 14:28:00 BST 2006


Andreas Bach Aaen wrote:
> Hi,
> 
> I would like to user dnsmasq as the one part of a PXE server on a 
> network. I would like to pass different options and filenames to 
> clients identified by different MAC addresses. How do I do this?
> 
> Regards,

First, set a tag based on the client's MAC address.

dhcp-host=net:blue,11:22:33:44:55:66

Then, tag the dhcp-boot lines you want sent, like this:

dhcp-boot=net:blue,blue-kernel,bootserver,192.68.1.1

and the options you want to be sent

dhcp-option=blue,3,192.168.1.2

A few things to note:

1) The syntax for tagging dhcp-boot and dhcp-option is different: the 
-boot needs "net:" to distinguish the tag from the filename, -option 
doesn't. Recent versions of dnsmasq will ignore net: if you add it to an 
-option line, but not earlier ones.

2) The semantics of untagged -option is different from -boot. Untagged 
options are always sent, untagged -boot is sent only when no tagged one 
matches.

3) Only one dhcp-host line is ever matched for a given client, so if 
you're already using dhcp-host to specify fixed addresses or hostnames, 
you need to add the tag to the existing dhcp-host line. Alternatively, 
you can match against a wildcarded MAC address using dhcp-mac:

dhcp-mac=blue,11:22:33:*:*:*

This is useful for matching a large class of hosts, when dhcp-host 
matcing might already be in use for more specific stuff. dhcp-mac is 
only available in more recent releases.

HTH

Simon.



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