FortiGate Next Generation Firewall utilizes purpose-built security processors and threat intelligence security services from FortiGuard labs to deliver top-rated protection and high performance, including encrypted traffic.
Each USB wireless modem has a specific dial-out ttyusb port,  usually the Vendor of the modem has this information. You can use the following FortiGate CLI commands to test the validity of the USB ports.

  • Under normal conditions you should see the following output:
FGT#diagnose sys modem com /dev/ttyusb1
Serial port: /dev/ttyusb1
Press Ctrl+W to exit.

  • The ports that do not respond will give this output:


FGT#diagnose sys modem com /dev/ttyusb0
Can not open modem device '/dev/ttyusb0': Broken pipe

Until FortiOS 4.0, each firmware version uses a specific USB port to dial out which cannot be changed. Since FortiOS 4.0MR1 you can select the USB dial-out port by CLI.

The new configuration command is :

config system modem
    set wireless-port <tty>

Where <tty> is the value of the port :

1 = ttyusb0
2 = ttyusb1
3 = ttyusb2

In conclusion, if you are running into this USB port mismatch issue, you can get information from your modem Vender about the USB port being used by the modem and then use the FortiOS modem command to match the port config.

FortiOS 4.0MR1 and above.