<filter name='allow-dhcp' chain='ipv4'>

    <!-- accept outgoing DHCP requests -->
    <!-- not, this rule must be evaluated before general MAC broadcast
         traffic is discarded since DHCP requests use MAC broadcast -->
    <rule action='accept' direction='out' priority='100'>
        <ip srcipaddr='0.0.0.0'
            dstipaddr='255.255.255.255'
            protocol='udp'
            srcportstart='68'
            dstportstart='67' />
    </rule>

    <!-- accept incoming DHCP responses from any DHCP server -->
    <rule action='accept' direction='in' priority='100' >
        <ip protocol='udp'
            srcportstart='67'
            dstportstart='68'/>
    </rule>

</filter>