+dnsserver inbound
+ntpclient inbound $ntp_servers
+
+## Provide NTP service to untrusted clients.
+iptables -A inbound -p udp -j ACCEPT \
+ --source-port 123 --destination-port 123 \
+ -s 172.29.198.0/23
+ip6tables -A inbound -p udp -j ACCEPT \
+ --source-port 123 --destination-port 123 \
+ -s 2001:ba8:1d9::/48
+ip6tables -A inbound -p udp -j ACCEPT \
+ --source-port 123 --destination-port 123 \
+ -s 2001:8b0:c92::/48