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.
Article Id 200042
Description This article describes the maximum radius secret key size supported.
Scope FortiOS.

For all maximum value usually it will be listed under 'print tablesize'.


However the radius maximum secret key length is not being specified on the table.


To further check the maximum length usable for radius secret key.

It is possible to basically test it using the following command:


# config user radius

    edit "test"

        set secret '999999999999999999999999...'


The above command is basically creating a test remote radius server profile on the FortiGate name 'test' and try to set a secret value which test the maximum length.


The following message printed from the Fortigate CLI will appear:


'Password is too long, max length is 128.'


In conclusion, the maximum length of Radius Secret key on the FortiOS is 128 characters.