Description | This article describes why radius user bypasses 2FA while connecting to SSL VPN. |
Scope | FortiGate. |
Solution |
Note: username-case-sensitive is enabled under the Radius server configuration (i.e. config user radius).
config user radius edit "FNF6" set server "172.16.3.2 " set secret ENC 4jC7L+ +2xWFoF4N+23984ysdfebnjkQ1tORYOmgoTnnuE set timeout 5 set all-usergroup disable set use-management-vdom disable set nas-ip 0.0.0.0 set acct-interim-interval 0 set radius-coa disable set radius-port 0 set h3c-compatibility disable set auth-type auto set source-ip '' set username-case-sensitive enable unset group-override-attr-type set password-renewal enable set password-encoding auto set acct-all-servers disable set switch-controller-acct-fast-framedip-detect 2 set interface-select-method auto unset switch-controller-service-type set rsso disable next end
The remote user on FortiGate is under the user definition 'jimmy1124' (radius user):
config user local edit "jimmy1124" set type radius set radius-server " FNF6" next end
Scenario 1: The remote radius user was added under the user group on FortiGate and further, this user group was being used under SSL VPN, which is incorrect. #1 success, mfa prompted , connectivity ok <- If the exact name is used. The reason user bypasses the #2 test is that username-sensitivity is not enabled under remote user(config user local), used under SSL VPN setting as mentioned previously, case sensitivity is enabled under radius server configuration (config user radius). As a fact, the user gets authenticated by FortiGate itself(proof: no MFA is prompted however the user is still allowed to log in).
Scenario2: The Radius server(FNF6) was added as a member under the user group on FortiGate and further this user group was being used under SSL VPN. #1 success, mfa prompted , connectivity ok <- If the exact name is used.
The user was prompted with 2FA, even if it did not match the exact username. The user auth request was forwarded to the radius server (if it had matched FortiGate, 2FA would not have been prompted as 2FA is not configured on FortiGate). However, some Radius servers need to be additionally configured with case sensitivity to make this config work. |
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