[Dnsmasq-discuss] Ideas for handing out "per blade" information

Paul Smith psmith at gnu.org
Thu Oct 22 23:18:02 BST 2009

On Thu, 2009-10-22 at 13:13 +0100, Simon Kelley wrote:
> network-ids are sadly misnamed: they have grown into much more general
> tags now. You can certainly set a net-id tag in a dhcp-host line, and 
> then use that to select the options to be sent to a particular host.

I see it clearly now; I don't know how I missed it.  My only excuse is
that the summary for dhcp-options talks about <network-id> while the
summary for dhcp-hosts talks about <netid>... but that's pretty
weak! :-)

So, suppose I wanted to provide some location information in the DHCP
response packet: something like rack number + chassis number + slot
number etc.  Say a sequence of N integers.  I checked the DHCP RFCs and
didn't find a DHCP option that seemed appropriate.  I'd prefer to do
this in the most standards-compliant way possible: anyone have a
suggestion for a good option to use?

> There's no way to change this information completely dynamically. You 
> can however put all the dhcp-host information into a file and point at
> that file with --dhcp-hostsfile, similarly with options and 
> dhcp-optsfile. Unlike a general configuration, these files _are_
> re-read when dnsmasq gets SIGHUP.

I guess I need to set up a cronjob or something to do this.  I can
imagine, though, that the latency between when you put a new board in,
and when the information is available to dnsmasq to respond properly to
DHCP requests from that board, could become a source of frustration.
I'll just have to code the board to continue to do DHCP requests until
it gets back a response containing the location information I need, or

Thanks for your help!

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