// newNetlinkHandler initializes a netlink socket in the current network namespace and returns
// an instance of netlinkHandler with the initialized socket.
func newNetlinkHandler() (handler, error) {
	socket, err := nl.GetNetlinkSocketAt(netns.None(), netns.None(), unix.NETLINK_NETFILTER)
	if err != nil {
		return nil, err
	}
	return &netlinkHandler{socket: socket}, nil
}