configuration - we have to read all the MAC addresses from netlink,
not bail when we find a suitable one.
Fix thinko in dhcp_update_configs - thanks to Hartmut for spotting
that.
Get a sensible address for the default DNS server even when using a
relay.
TODO
hostname handling.
update DHCP6 configs from dns
parse domain=<domain>,<IPv6 range>
pretty-print counted string options.
DECLINE messages
lease-script fro DHCPv6