ip6tables: allow dhcp6d from aws

While we actually use SLAAC in aws, there's a dhcp6d sending out the
router advertisements, so without that the instance doesn't get an ipv6
ip and just doesn't work. With this it does.

Signed-off-by: Kevin Fenzi <kevin@scrye.com>

roles/base/templates/iptables/ip6tables

@@ -14,9 +14,11 @@
 -A INPUT -m state --state ESTABLISHED,RELATED -j ACCEPT
 
 # Established connections allowed
--A INPUT -m state --state RELATED,ESTABLISHED -j ACCEPT
 -A OUTPUT -m state --state RELATED,ESTABLISHED -j ACCEPT
 
+# allow dhcp6d from aws
+-A INPUT -d fe80::/64 -p udp -m udp --dport 546 --sport 547 -j ACCEPT
+
 # if the blocked_ips is defined - drop them
 {% if blocked_ip_v6 is defined %}
 {% for ip in blocked_ip_v6 %}