Technical Tip: Supplementary explanation for 'SSL VPN with LDAP-integrated certificate authentication' on FortiOS Administration Guide

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Description

This article describes a supplementary explanation to prevent an unnecessary problem for configuring SSL VPN that requires users to authenticate using a certificate with LDAP UserPrincipalName checking.

Scope

FortiOS v6.4, v7.0, v7.2.

Solution

1) Do not configure 'client-certificate' and 'user-peer'.

As illustrated in FortiOS Administration Guide (VPN -> SSL VPN -> SSL VPN with LDAP-integrated certificate authentication -> Sample configuration -> To configure SSL VPN using the CLI: > 6. Configure SSL VPN settings), it is not necessary to configure the following (a) and (b).
If configuring it, this SSL VPN scenario does not work as expected.

# config vpn ssl settings
config authentication-rule
    edit 1
        set groups “xxx"
        set portal “xxx"
        set client-cert enable <- (a).
        set user-peer “xxx" <- (b).

    next
end
end

2) Disable 'Authentication' on FortiClient.

This is not stated in the FortiOS Administration Guide (VPN -> SSL VPN -> SSL VPN with LDAP-integrated certificate authentication -> Sample configuration -> To see the results of tunnel connection: > 3. Add a new connection), but as stated in FortiClient Administration Guide (Remote Access -> Configuring VPN connections -> Configuring an SSL VPN connection), it is necessary to disable 'Authentication' since account/password is not needed in this scenario.

Related documents:
https://docs.fortinet.com/document/fortigate/7.2.3/administration-guide/751987/ssl-vpn-with-ldap-int...

https://docs.fortinet.com/document/forticlient/7.0.7/administration-guide/205286/configuring-an-ssl-...