'The standard allow-dhcp-server filter is an <ip> one, so it uses
ebtables to allow traffic through. Without a corresponding rule in
iptables, it\'ll get blocked anyway.'

def nova_dhcp_filter(self):

    uuid = self._get_filter_uuid('nova-allow-dhcp-server')
    return ("<filter    name='nova-allow-dhcp-server'    chain='ipv4'>\n                                                                                <uuid>%s</uuid>\n                                                                                <rule    action='accept'    direction='out'\n                                                                                                        priority='100'>\n                                                                                        <udp    srcipaddr='0.0.0.0'\n                                                                                                            dstipaddr='255.255.255.255'\n                                                                                                            srcportstart='68'\n                                                                                                            dstportstart='67'/>\n                                                                                </rule>\n                                                                                <rule    action='accept'    direction='in'\n                                                                                                        priority='100'>\n                                                                                        <udp    srcipaddr='$DHCPSERVER'\n                                                                                                            srcportstart='67'\n                                                                                                            dstportstart='68'/>\n                                                                                </rule>\n                                                                        </filter>" % uuid)
