Troubleshooting Tip: Unable to access the FortiGate due to a DDNS issue on FortiGate

[anoushiravan]

Description	This article describes how to fix an issue that may prevent users from using DDNS to access the FortiGate GUI instead of using the IP address.
Scope	FortiGate.
Solution	In the example used in this article, the IP address of the wan1 interface is used for DDNS on FortiGate. FortiGate is unable to update the DDNS due to a connection error. The solution will explain how to update the DDNS in FortiGate. Below is the IP address of the interface. config system interface edit "wan1" set ip 10.109.17.53 255.255.240.0 set allowaccess ping https ssh http next edit "dmz" set ip 10.10.5.3 255.255.240.0 set allowaccess ping https ssh http next end Below is the DDNS setting for fortiservice.fortiddns.com. config system ddns edit 1 set ddns-server FortiGuardDDNS set ddns-domain "fortiservice.fortiddns.com" set use-public-ip enable set monitor-interface "wan1" next end To learn the IP address of the FortiGuard DDNS server and which port number is used by FortiGate to connect to the DDNS server, run the following command. Example output is attached. diagnose test application ddnscd 3 FortiDDNS status: ddns_ip=173.243.138.225, ddns_ip6=::, ddns_port=443 svr_num=1 domain_num=3 <<<----- svr[0]= 173.243.138.225 domain[0]= fortiddns.com domain[1]= fortidyndns.com domain[2]= float-zone.com Since the DDNS server IP address is set to 0.0.0.0 and the connection port is 443 by default under the FortiGuard settings, FortiGate will connect to the resolved IP of the domain globalddns.fortinet.net with destination port 443, unless a DDNS server IP address is configured specifically as follows. config system fortiguard set ddns-server-ip 173.243.138.225 set ddns-server-port 443 end Run the following debug commands in the CLI to find the root cause of the DDNS issue in FortiGate: diagnose debug dis diagnose debug reset diagnose debug cons time en diagnose debug en diagnose debug app ddnscd -1 Debug messages will be enabled for 30 minutes. .... 136003188-Connected # 2023-04-27 22:30:18 1659713418: next wait timeout 9 seconds 2023-04-27 22:30:28 1659713428: Start to update FortiGuardDDNS (fortiservice.fortiddns.com) 2023-04-27 22:30:28 1659713428: next wait timeout 10 seconds 2023-04-27 22:30:38 1659713438: next wait timeout 10 seconds 2023-04-27 22:30:48 1659713448: next wait timeout 10 seconds 2023-04-27 22:30:58 fgt_ddns_socket()-892: cannot connect to 173.243.138.225:443 2023-04-27 22:30:58 1659713458: Failed on update FortiGuardDDNS (fortiservice.fortiddns.com), due to internal/config/connect/io err 2023-04-27 22:30:58 1659713458: Failed on update FortiGuardDDNS (fortiservice.fortiddns.com), next try in 60 seconds 2023-04-27 22:30:58 1659713458: next wait timeout 4 seconds 2023-04-27 22:31:03 name=globalddns.fortinet.net, id=5504, cb=0x82b8b8 2023-04-27 22:31:03 name=globalddns.fortinet.net, id=5505, cb=0x82b8b8 It is therefore necessary to ensure there is a route through the correct interface in FortiGate to the DDNS server. Check which interface there is an internet connection from: get router info routing-table details 173.243.138.225 Routing table for VRF=0 Routing entry for 0.0.0.0/0 Known via "static", distance 10, metric 0, best * vrf 0 10.109.31.254, via wan1 In the above output, the FortiGate has a default route 0.0.0.0 through the wan1 interface. However, an incorrect interface and source IP have been configured in FortiGuard settings. As a result, FortiGate will not be able to connect to the FortiGuard server: config system fortiguard set source-ip 10.10.5.3 set interface-select-method specify set interface dmz end Note: If the FortiGate is configured under VDOM's, on both DNS and FortiGuard Setting, to avoid specify any interface, keep  default as 'Auto'. To resolve the issue, a correct source IP and interface must be configured under FortiGuard settings. Since the internet is accessible through a wan1 interface, the FortiGuard settings have been changed as follows: config system fortiguard set source-ip 10.109.17.53 set interface-select-method specify set interface wan1 end Check the new details of the updated DDNS on FortiGate: config sys ddns edit 1 get ddnsid : 1 ddns-server : FortiGuardDDNS server-type : ipv4 ddns-domain : fortiservice.fortiddns.com use-public-ip : enable addr-type : ipv4 update-interval : 0 monitor-interface : "wan1" bound-ip : 10.109.17.53 Note: if the use-public-ip setting in DDNS is disabled on FortiGate, the bound-ip will not be visible in the above output. To ensure the DDNS is updated (when a correct IP address is set for the DDNS in FortiGate): exe ping fortiservice.fortiddns.com PING fortiservice.fortiddns.com (10.109.17.53): 56 data bytes 64 bytes from 193.86.26.196: icmp_seq=0 ttl=255 time=0.2 ms 64 bytes from 193.86.26.196: icmp_seq=1 ttl=255 time=0.1 ms 64 bytes from 193.86.26.196: icmp_seq=2 ttl=255 time=0.3 ms 64 bytes from 193.86.26.196: icmp_seq=3 ttl=255 time=0.3 ms 64 bytes from 193.86.26.196: icmp_seq=4 ttl=255 time=0.3 ms --- fortiservice.fortiddns.com ping statistics --- 5 packets transmitted, 5 packets received, 0% packet loss round-trip min/avg/max = 0.1/0.2/0.3 ms di test application ddnscd 5 2023-04-27 23:26:21 0, id=1, ddns entry (intf:wan1 domain:fortiservice.fortiddns.com, address:10.109.17.53, use interface ip), server:FortiGuardDDNS globalddns.fortinet.net, status:updated Screenshot from successful GUI access through DDNS: Related articles: config system ddns - FortiOS CLI reference Technical Tip: How to transfer the DDNS record to new FortiGate.