Run script when acquiring DHCP lease?

[Laurens Vets]

Nick Guenther wrote:
> On 8/7/06, Laurens Vets <laurens at daemon.be> wrote:
> 
>>Hi all,
>>
>>As the subject suggests, I want to run a script when some of my OpenBSD
>>machines have acquired a new DHCP lease, something similar to
>>ppp.linkup.  The best I came up with was to write a script which checks
>>my current ip every x minutes or so and compares that to the one x
>>minutes ago.  If they don't match -> run a script which does something
>>(e.g. send an email...)
>>
>>Can't this be done in a simpler way on OpenBSD?
>>
> 
> 
> hotplugd(8) was my first thought but it only works on attachment of
> devices. You might look into scanning /var/db/dhclient.leases.ifname
> as documented in dhclient(8) instead of ifconfig. And use cron if you
> aren't already, instead of rolling your own timing.
> 
> Polling isn't a useless technique, it's just wasteful sometimes.
> Remember: "when in doubt, use brute force" [1]
> 
> [1] http://www.faqs.org/docs/artu/ch01s06.html

Thanks for your answer.  With "checks my current ip every x minutes or 
so and compares that to the one x minutes ago." I actually meant cron :)

Guess this is the 'best' way then :)

Laurens