[Swan] Libreswan and DHCP

Paul Wouters paul at nohats.ca
Fri Dec 11 19:37:06 UTC 2015

On Fri, 11 Dec 2015, Nick Howitt wrote:

>       Note that pluto "orients" connections to determine if it is "left" or
>       "right" when the connection loads. So a network change might require
>       re-orienting connections. That's fine for connections loaded and not
>       up. What to do with active tunnels is more tricky.
> But aren't the active tunnels de facto dead as the far end at that point is still trying to communicate to the old IP address and
> may even have to wait for DNS propagation to be able to reconnect?

Not neccessarilly. For instance of an IP address is only added to the
system, and the default route is changed from one interface to another

> Have a look at /etc/dhcp/dhclient-exit-hooks. The only thing is, when I tried using it in a very basic way, it triggered every time
> the lease was renewed. There may be options only to trigger on IP change. I stopped looking at that point as my "dynamic IP" is
> virtually static and has not changed in over a year now.

I had similar issues with dhclient hooks for my Philips Hue lights :)

When I'm coming home, and my phone joins the wifi, and it is dark and
the lights are off, turn on the lights. However, that also resulted in
the lights turning on in the middle of night on a DHCP lease renewal.


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