On Mon, 14 May 2018 19:36:12 -0400
Quartz <[email protected]> wrote:
> > Currently there is no facility in dhclient(8) to issue RELEASE
> > messages. I had no recollection of adding such a thing, and a
> > quick
>
> > confirmed there is no DHCPRELEASE related code.
>
> Ergh. OK thanks, that's super annoying that it's not there.
>
> >Which
> > signal(s) are used elsewhere to trigger RELEASE? Goggle is not
> > coughing up an obvious answer. :-)
>
> It varies, IIRC on at least on other linux or bsd distro sending HUP
> took a more literal approach ("hang up and leave") and sent a DHCP
> release before nuking its lease cache, and I'm pretty sure somewhere
> else you could send "SIGUSR2" or something.
>
On Red Hat/Debian (and derivatives) they use dhclient which has a -r
switch to release the lease. From the man page:
-r Release the current lease and stop the running DHCP client as
previously recorded in the PID file. When shutdown via this method
dhclient-script will be executed with the specific reason for
calling the script set. The client normally doesn't release the
current lease as this is not required by the DHCP protocol but some
cable ISPs require their clients to notify the server if they wish to
release an assigned IP address.
