Technical Tip: USB Tethering using Mobile Phone on FortiGate

[adimailig]

Description	This article describes how to enable USB Tethering using a mobile phone on FortiGate.
Scope	FortiGate.
Solution	USB Tethering is the process of sharing the internet connection of a mobile device to another device, like using a USB cable. In this deployment, the mobile device is connected directly to FortiGate using a USB cable.  Enable USB Tethering on the mobile phone. Different models of mobile phones have different ways to enable USB Tethering. Check the mobile phone manual to know how to enable this service.   Check if the mobile device is connected and make sure that the mobile phone is detected with 'Driver=rndis_host'. FortiWiFi-60E # fnsysctl cat /proc/bus/usb/devices T:  Bus=01 Lev=01 Prnt=01 Port=00 Cnt=01 Dev#=  4 Spd=480  MxCh= 0 D:  Ver= 2.00 Cls=00(>ifc ) Sub=00 Prot=00 MxPS=64 #Cfgs=  1 P:  Vendor=0e8d ProdID=2004 Rev= 2.23 S:  Manufacturer=INFINIX MOBILITY LIMITED S:  Product=Infinix X6815B S:  SerialNumber=081XXXXXXXXXXXXXX C:* #Ifs= 2 Cfg#= 1 Atr=80 MxPwr=500mA A:  FirstIf#= 0 IfCount= 2 Cls=e0(wlcon) Sub=01 Prot=03 I:* If#= 0 Alt= 0 #EPs= 1 Cls=e0(wlcon) Sub=01 Prot=03 Driver=rndis_host E:  Ad=82(I) Atr=03(Int.) MxPS=   8 Ivl=32ms I:* If#= 1 Alt= 0 #EPs= 2 Cls=0a(data ) Sub=00 Prot=00 Driver=rndis_host E:  Ad=81(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms E:  Ad=01(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms Enable LTE modem on FortiGate using the below command. This will enable the interface 'wwan'. There are instances where 'wimax-4g-usb' should be enabled as well. config system lte-modem     set status enable end config system global     set wimax-4g-usb enable end Interface 'wwan' will get an IP address and default gateway via DHCP from the mobile phone USB tethering.    FortiWiFi-60E # get router info routing-table all Codes: K - kernel, C - connected, S - static, R - RIP, B - BGP        O - OSPF, IA - OSPF inter area        N1 - OSPF NSSA external type 1, N2 - OSPF NSSA external type 2        E1 - OSPF external type 1, E2 - OSPF external type 2        i - IS-IS, L1 - IS-IS level-1, L2 - IS-IS level-2, ia - IS-IS inter area        V - BGP VPNv4        * - candidate default Routing table for VRF=0 S*      0.0.0.0/0 [1/0] via 10.153.176.187, wwan, [1/0] S       10.81.3.170/32 [254/0] is a summary, Null, [1/0] C       10.153.176.0/24 is directly connected, wwan Note that there is a known issue (1181444) related to USB-Tethering failing to work on FortiGate 91G when configuring it as a WWAN connection. This issue has been resolved in: v7.4.9 (already available). v7.6.5 (scheduled to be released in November 2025). v8.0.0 (scheduled to be released in March 2026). The timelines for firmware releases are estimated and may be subject to change.