Technical Tip: How to return FortiGate firewall to NAT mode from Transparent mode

[Mrinmoy]

Description	This article describes how to configure a FortiGate firewall to NAT mode again from Transparent mode.
Scope	FortiGate v6.4 or above.
Solution	Option 1 (GUI): Under System -> Settings there is an option (System Operation Settings) to to switch from transparent mode to NAT mode: Option 2 (CLI): To configure NAT mode from the CLI, the interface IP with the subset mask and gateway should be updated.  Before changing: config system settings set opmode nat set ip 192.168.100.150 255.255.255.0 set device port1 set gateway 192.168.100.1 end Changing to NAT mode. Before changing: Branch # get system status Version: FortiGate-VM64-KVM v7.4.1,build2463,230830 (GA.F) Security Level: 1 Secure Boot: Disabled Virus-DB: 1.00000(2018-04-09 18:07) Extended DB: 1.00000(2018-04-09 18:07) Extreme DB: 1.00000(2018-04-09 18:07) AV AI/ML Model: 0.00000(2001-01-01 00:00) IPS-DB: 6.00741(2015-12-01 02:30) IPS-ETDB: 6.00741(2015-12-01 02:30) APP-DB: 6.00741(2015-12-01 02:30) FMWP-DB: 24.00020(2024-02-13 17:03) IPS Malicious URL Database: 1.00001(2015-01-01 01:01) IoT-Detect: 0.00000(2022-08-17 17:31) OT-Detect-DB: 0.00000(2001-01-01 00:00) OT-Patch-DB: 0.00000(2001-01-01 00:00) OT-Threat-DB: 6.00741(2015-12-01 02:30) IPS-Engine: 7.00509(2023-08-10 23:14) Serial-Number: FGVM01TM23000591 License Status: Warning VM Resources: 1 CPU/1 allowed, 1992 MB RAM Log hard disk: Available Hostname: Branch Private Encryption: Disable Operation Mode: Transparent Current virtual domain: root Max number of virtual domains: 10 Virtual domains status: 0 in NAT mode, 1 in TP mode Virtual domain configuration: disable FIPS-CC mode: disable Current HA mode: standalone Branch point: 2463 Release Version Information: GA FortiOS x86-64: Yes System time: Wed Feb 28 12:13:03 2024 Last reboot reason: warm reboot Branch # After changing: Branch # get system status Version: FortiGate-VM64-KVM v7.4.1,build2463,230830 (GA.F) Security Level: 1 Secure Boot: Disabled Virus-DB: 1.00000(2018-04-09 18:07) Extended DB: 1.00000(2018-04-09 18:07) Extreme DB: 1.00000(2018-04-09 18:07) AV AI/ML Model: 0.00000(2001-01-01 00:00) IPS-DB: 6.00741(2015-12-01 02:30) IPS-ETDB: 6.00741(2015-12-01 02:30) APP-DB: 6.00741(2015-12-01 02:30) FMWP-DB: 24.00020(2024-02-13 17:03) IPS Malicious URL Database: 1.00001(2015-01-01 01:01) IoT-Detect: 0.00000(2022-08-17 17:31) OT-Detect-DB: 0.00000(2001-01-01 00:00) OT-Patch-DB: 0.00000(2001-01-01 00:00) OT-Threat-DB: 6.00741(2015-12-01 02:30) IPS-Engine: 7.00509(2023-08-10 23:14) Serial-Number: FGVM01TM23000591 License Status: Valid VM Resources: 1 CPU/1 allowed, 1992 MB RAM Log hard disk: Available Hostname: Branch Private Encryption: Disable Operation Mode: NAT Current virtual domain: root Max number of virtual domains: 10 Virtual domains status: 1 in NAT mode, 0 in TP mode Virtual domain configuration: disable FIPS-CC mode: disable Current HA mode: standalone Branch point: 2463 Release Version Information: GA FortiOS x86-64: Yes System time: Wed Feb 28 12:08:49 2024 Last reboot reason: warm reboot Branch #