Looking at https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/7/..., it sounds like the preferred approach is to use something like: <filter name='no-ipv6-spoofing' chain='ipv6-ip' priority='-710'> <rule action='return' direction='out' priority='500'> <ipv6 srcipaddr='$IPV6[@1]' srcipmask='$IPV6_MASK[@1]'/> </rule> <rule action='drop' direction='out' priority='1000'/> </filter> The documentation reads: Assign concrete values to SRCIPADDRESSES and DSTPORTS as shown: SRCIPADDRESSES = [ 10.0.0.1, 11.1.2.3 ] DSTPORTS = [ 80, 8080 ] But I'm not sure how to pass through an array of <parameter>s in the filterref. Is this possible? On Wed, Jan 1, 2020 at 12:39 PM Brooks Swinnerton <bswinnerton(a)gmail.com&gt; wrote: > Hello, > > I have a nwfilter that I'm using to ensure that libvirt domains can't > spoof IPv6 traffic. It looks like this: > > <filter name='no-ipv6-spoofing' chain='ipv6-ip' priority='-710'> > <rule action='return' direction='out' priority='500'> > <ipv6 srcipaddr='$IPV6' srcipmask='$IPV6MASK'/> > </rule> > <rule action='drop' direction='out' priority='1000'/> > </filter> > > The goal is to allow any traffic coming from the entire prefix (e.g. > 2001:db8::/32). This theoretically would work fine when passing in the > variables from the domain definition like so: > > <filterref filter='no-ipv6-spoofing'> > <parameter name='IPV6' value='2001:db8:1:6:dc:d2ff:fef2:2181'/> > <parameter name='IPV6_MASK' value='32'/> > </filterref> > > But the problem comes when wanting to allow multiple prefixes (and thus > multiple $IPV6 and $IPV6_MASK variables). If there is more than one > definition of $IPV6, how could I associate it with a corresponding > $IPV6_MASK? > > Ideally I would be able to pass an address in CIDR notation directly to > srcipaddr, but I don't believe that's an option. > > Any guidance would be appreciated. The ultimate goal is to automate this > process, so having something like $IPV6_1 and $IPV6_1 would be less than > ideal. >