How can I monitor the NIC status(up/down) in a C program without polling the kernel?

Question

Now I need to get the status of the NIC(up or down) in the real time. That means I have to catch the kernel interrupt when the NIC up or down in a blocked loop.

The

Answer 1

Yes, open a netlink socket and listen to the RTMGRP_LINK (network interface create/delete/up/down events) multicast groups.

The netlink man page here has a specific example to do this.