Re: cross namespace interface notification for tun devices

On Mon, Sep 18, 2017 at 11:47 AM, Jason A. Donenfeld [off-list ref] wrote:

Hey guys,

It's possible to create a tun device in a process in namespace A and
then move that interface to namespace B. The controlling process in A
needs to receive notifications on when the interface is brought up or
down. It can receive these notifications via netlink while the
interface lives in A but not when it moves to B.

By "notification" I assume you mean netlink notification.

Any tricks or APIs to get around this?

The question is why does the process in A still care about
the device sitting in B?

Also, the process should be able to receive a last notification
on IFF_UP|IFF_RUNNING before device is finally moved to B.
After this point, it should not have any relation to netns A
any more, like the device were completely gone.