[Dnsmasq-discuss] DHCP options and SIGHUP
simon at thekelleys.org.uk
Mon Jul 13 11:50:25 BST 2009
Olaf Westrik wrote:
> Hi everyone,
> I have a question and/or problem with using various DHCP options and
> reloading them by using SIGHUP.
> Following use case:
> 'global' DHCP settings (rarely changing) and several static leases, some
> of which using dhcp-boot for PXE boot.
> Now I would like to reread the static leases after changes have been
> made by using SIGHUP. No problem if I put the dhcp-host configuration
> lines in a file referenced by dhcp-hostsfile, but what to do with the
> dhcp-boot lines?
> Any thoughts?
It's (mostly) possible. The trick is to use dhcp-optsfile which, like
dhcp-hostfile get re-read on SIGHUP.
dhcp-optsfile contains dhcp-option lines, not dhcp-boot lines, but the
filename and servername information in dhcp-boot can be represented as
So, if you have
dhcp-host=<mac address>,<IP address>,net:<tag>
then you can put
<mac address>,<IP address>,net:<tag>
in a dhcp-hostfile
and get the same effect, but the configuration is re-read on SIGHUP.
The only thing that this doesn't work for is the server address field in
dhcp-boot, since there's no option defined to represent this. As long as
you're relying on the default that's OK. A "pseudo option" should
probably be defined for this data too, to fix this hole.
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