> On Jan 25, 2016, at 4:43, Lennart Poettering <[email protected]> wrote: > > On Sat, 23.01.16 14:22, Johannes Ernst ([email protected]) wrote: > >> Is there a way to receive a callback when a dhcp client-side IP address >> changes? >> >> Use case: dynamic DNS update. > > On Linux changes regarding IP configuration are reported via rtnl (aka > routing netlink). This works regardless how the IP address was > required, and without any extra API from networkd.
So the way to do this would be to write a little daemon that listens to these events [1] > RTM_NEWLINK (kernel→user) > This message type is used in reply to a RTM_GETLINK request and carries the > configuration and statistics of a link. If multiple links need to be sent, > the messages will be sent in form of a multipart message. > > The message type is also used for notifications sent by the kernel to the > multicast group RTNLGRP_LINK to inform about various link events. It is > therefore recommended to always use a separate link socket for link > notifications in order to separate between the two message types. > and exec’s something in response? I agree it’s strange nobody has done that yet, apparently. Cheers, Johannes. [1] https://www.infradead.org/~tgr/libnl/doc/route.html
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