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NAT DNS Service to LAN address

I want IoT devices to use my internal DNS server.  I setup a NAT rule to translate inbound DMZ interface to destination internal DNS server and I have a matching firewall rule but the traffic is getting dropped.

IoT device calls to 8.8.8.8 on Port 53 and the NAT rule translates correctly but XG fails to match the firewall rule even though it matches the log message details exactly.

Could this be a bug, possibly the order of operations, or am missing something in my setup?

2020-11-15 22:21:31Firewallmessageid="00002" log_type="Firewall" log_component="Firewall Rule" log_subtype="Denied" status="Deny" con_duration="0" fw_rule_id="6" nat_rule_id="1" policy_type="1" user="" user_group="" web_policy_id="2" ips_policy_id="0" appfilter_policy_id="0" app_name="" app_risk="0" app_technology="" app_category="" vlan_id="" ether_type="IPv4 (0x0800)" bridge_name="" bridge_display_name="" in_interface="Port2.8" in_display_interface="Port2.8" out_interface="Port2.11" out_display_interface="Port2.11" src_mac="f8:0f:f9:4d:c3:4d" dst_mac="" src_ip="192.168.8.12" src_country="" dst_ip="192.168.11.225" dst_country="" protocol="UDP" src_port="42410" dst_port="53" packets_sent="0" packets_received="0" bytes_sent="0" bytes_received="0" src_trans_ip="" src_trans_port="0" dst_trans_ip="" dst_trans_port="0" src_zone_type="" src_zone="" dst_zone_type="" dst_zone="" con_direction="" con_id="" virt_con_id="" hb_status="No Heartbeat" message="" appresolvedby="Signature" app_is_cloud="0"

Packet Capture



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  • Thanks, that worked.  I also found I could NAT the DNS to the Sophos interface IP 192.168.8.1 without any Firewall rule and that worked also.

    For DNAT firewall rules, I think the "dst_trans_ip" should be used instead of the "dst_ip".  Otherwise your NAT rules become your firewall.