centos - Firewalld blocks IPv6, ignores config

itemprop="text">

I'm trying to setup an IPv6 web-server
on CentOS 7.2 with NGINX. I have tested my IPv6 connectivity outgoing and incoming -
everything works. My IP, AAAA records, etc as fine as well. Essentially everything is OK
until I enable FirewallD.

I have it set up to
default to the drop zone with eth0 interface. I have enabled dhcpv6-client, http, https
and ssh (ssh is on a custom port). When the firewall is enabled no IPv6 traffic can
leave or enter the machine. Traceroute6 to anything (even the gateway) only goes to
localhost. If I disable the firewall, it's all
good.

I have no idea why this is happening. I
couldn't find anything online in order to make FirewallD apply the same IPv4 config to
the IPv6 traffic. I personally thought, it would do that automatically, as all of its
commands are IP protocol agnostic.

Any help is
much appreciated.

itemprop="text">

class="normal">Answer

I ran into the same issue. After following the logic through the rules that
firewalld puts in I found that the drop zone was blocking ipv6 icmp that is needed to
find the ipv6 neighbors. There is a rule to allow all ipv6 icmp but firewalld puts it
after the input zones which is where the drop rules
go.

If you want to see this for yourself just
look at the output from 'ip6tables -L -n -v'

So,
a quick and dirty fix is to do
this:

firewall-cmd --permanent
            --direct --add-rule ipv6 filter INPUT 0 -p icmpv6 -j
            ACCEPT

Firewalld puts
the direct rules before the other input rules so that will happen before the drop rules.
If you want to block things like ping you would also use a direct rule but you would
need it before the rule above.

You
would do something
like:

firewall-cmd --permanent
            --direct --add-rule ipv6 filter INPUT 0 -p icmpv6 --icmpv6-type 128 -j
            DROP
firewall-cmd --permanent --direct --add-rule ipv6 filter INPUT 1 -p
            icmpv6 -j ACCEPT

The
priorities will keep them in order.