Fortinet L2TP VPN Integration with AuthPoint

Deployment Overview

This document describes how to set up a FortiGate unit and AuthPoint multi-factor authentication (MFA) for Active Directory users that use an L2TP VPN client.

Your FortiGate unit must already be configured and deployed before you set up MFA with AuthPoint.

If the L2TP VPN client is only used by local AuthPoint users, you do not have to configure Microsoft NPS or enable MS–CHAPv2. NPS is only required for users synced from Active Directory or an LDAP database.

Users synced from Azure AD cannot authenticate to RADIUS client resources that use MS-CHAPv2.

Integration Summary

The hardware and software used in this guide include:

  • WatchGuard Cloud
  • Fortinet FortiGate 60E
    • FortiOS v6.2.0 or higher
  • WatchGuard AuthPoint Gateway
    • v5.3.1.184 or higher
  • Windows Server 2016 with Microsoft Network Policy Server (NPS) and Active Directory Domain Services

Test Topology

This diagram shows the test topology

Topology diagram

Before You Begin

Before you begin these procedures, make sure that:

  • You have installed and configured v5.3.1 or higher of the AuthPoint Gateway (see About Gateways)
  • You have installed and configured Active Directory Domain Services
  • You have installed Network Policy and Access Services, which includes Network Policy Server (NPS)

Configure Microsoft NPS Server

To enable users synced from Active Directory to successfully authenticate with MS-CHAPv2, you must configure Microsoft Network Policy Server (NPS). NPS is required to validate the user credentials from MS-CHAPv2 RADIUS requests against Active Directory.

In our example, Active Directory and NPS are installed on the same server. If NPS is installed on a different server than Active Directory, you must register NPS in the Active Directory domain and log in as a domain administrator.

For instructions to configure Active Directory Domain Services, see the Microsoft documentation for Active Directory.

If the L2TP VPN client is only used by local AuthPoint users, you do not have to configure Microsoft NPS. Continue to the Configure the FortiGate Unit section.

  1. On the Windows server, run Server Manager.
  2. Select Tools > Network Policy Server.
    The Network Policy Server console appears.
  3. Select RADIUS Clients and Servers > RADIUS Clients.
  4. Right-click RADIUS Clients and select New.
    The New RADIUS Client window appears.
  5. In the Friendly name text box, type a name.
  6. In the Address (IP or DNS) text box, type the IP address of the AuthPoint Gateway. In our example, the IP address of the AuthPoint Gateway is 192.168.100.20.
  7. In the Shared secret and Confirm shared secret text boxes, type a shared secret key. This key is used to communicate with the RADIUS server (AuthPoint Gateway).

    You must use the same shared secret key when you configure your RADIUS client and your RADIUS client resource.

  8. Click OK.
  9. Screenshot of nps, picture 2

  10. Select Polices > Connection Request Policies. Make sure the default policy is enabled.
  11. Screenshot of nps, picture 3

  12. Right-click Network Policies and select New.
    The New Network Policy window appears.
  13. In the Policy Name text box, type a name for this policy. In our example, we type ecotest.
  14. Click Next.
  15. In the Specify Conditions section, click Add.
  16. Select User Groups. Click Add > Add Groups.
  17. In the Enter the object name to select text box, type the group name. The name of this group must match the name of the Active Directory group your users belong to.
  18. Click OK.
  19. Click OK.
  20. Click Next.
  21. Screenshot of nps, picture 4

  22. Click Next.
  23. In the Configure Authentication Methods section, clear the User can change password after it has expired check box.
  24. Click Next.
  25. Screenshot of nps, picture 5

  26. Click Next.
  27. In the Configure Settings section, click Add. In our example we use group authentication. If you want to use user authentication, skip Steps 23-29.
  28. From the Attributes list, select Filter-Id. Click Add.
  29. Click Add.
  30. In the Attribute Information window, in the text box type a group name. The name of this group must match the name of the Active Directory group your users belong to.
  31. Screenshot of nps, picture 6

  32. Click OK.
  33. Click OK.
  34. Click Close.
  35. Click Next.
  36. Screenshot of nps, picuture 7

  37. Click Finish.
  38. Screenshot of nps, picture 8

  39. Right-click NPS (Local) and select Register server in Active Directory.
  40. Click OK.
  41. Click OK.

Configure the FortiGate Unit

Follow these steps to configure the FortiGate unit.

Configure a RADIUS Server

  1. Log in to the FortiGate 60E Web UI at https://<IP address of FortiGate 60E>. The default IP address is 192.168.1.99.
  2. Select User & Device > RADIUS Servers.
  3. Click Create New.
  4. In the Name text box, type a name for the RADIUS server. In our example, we type AuthPointGateway.
  5. In the IP/Name text box, type the IP address of the RADIUS server (AuthPoint Gateway).
  6. In the Secret text box, type the shared secret key that you specified in the Configure Microsoft NPS Server section. This is the password that the RADIUS server (AuthPoint Gateway) and the RADIUS client (Firebox) will use to communicate.

    You must use the same shared secret key when you configure your RADIUS client resource in AuthPoint.

  7. Screenshot of the RADIUS server

  8. Click OK.
  9. Click Save.
  10. Screenshot of the configured RADIUS server

Configure Users and Groups

  1. Select User & Device > User Groups.
  2. Click Create New.
  3. In the Name text box, type a name for the group. The name of this group must match the name of the Active Directory group your users belong to. In our example, we type EcoTest.
  4. From the Type drop-down list, select Firewall.
  5. Screenshot that shows a user being added

  6. Click OK.
  7. Screenshot of the added user

  8. Select User & Device > User Definition.
  9. Click Create New.
  10. Select Remote RADIUS User.
  11. Screenshot that shows the User Type selection

  12. Click Next.
  13. In the Username text box, type the user name for your user. This user name must match the user name in Active Directory. In our example, we type mytest.
  14. From the RADIUS Server drop-down list, select AuthPointGateway.
  15. Screenshot of the name and RADIUS server for the RADIUS user

  16. Click Next.
  17. In the Email Address text box, type the email address for this user.
  18. Screenshot of the email address for the RADIUS user

  19. Click Next.
  20. Enable User Group.
  21. Add the user group that you created. In our example, we add the EcoTest user group.
  22. Screenshot of the group for the RADIUS user

  23. Click Submit.
  24. Screenshot of the added RADIUS user

Configure L2TP VPN

  1. Select VPN > IPsec Wizard.
  2. In the Name text box, type the VPN name. In our example, we type L2TP.
  3. For Template Type, select Remote Access.
  4. For Remote Device Type, select Native and Windows Native.
  5. Screenshot of VPN setup

  6. Click Next.
  7. From the Incoming Interface drop-down list, select wan1.
  8. For Authentication Method, select Pre-shared Key.
  9. In the Pre-shared Key text box, type a pre-shared key.

    You must use the same pre-shared key when you configure the L2TP VPN client.

  10. From the User Group drop-down list, select the user group that you created in the previous section. In our example, we select the EcoTest user group.

    Screenshot of the Authentication settings for the VPN

  1. Click Next.
  2. From the Local Interface drop-down list, select the internal interface that connect to the AuthPoint Gateway.
  3. For Local Address, add an address object that is in this LAN. In our example, the IP address is 192.168.18.0/24.
  4. In the Client Address Range text box, type an IP address range. In our example, we type 192.168.100.1-192.168.100.100.
  5. In the Subnet Mask text box, type 255.255.255.0.
  6. Screenshot of the VPN policy and routing settings

  7. Click Create.
  8. Screenshot that shows the VPN Creation Wizard completed

Configure AuthPoint

Before AuthPoint can receive authentication requests from your FortiGate unit, you must add a RADIUS client resource in AuthPoint. You must also assign an resource for the RADIUS client resource to the AuthPoint user group(s) that will authenticate.

Add a RADIUS Client Resource in AuthPoint

From the AuthPoint management UI:

  1. From the navigation menu, select Resources.
  2. From the Choose a Resource Type drop-down list, select RADIUS Client. Click Add Resource.

  1. In the Name text box, type a descriptive name for the resource.
  2. In the RADIUS client trusted IP or FQDN text box, type the IP address that your RADIUS client uses to send RADIUS packets to the AuthPoint Gateway. This must be a private IP address.
  3. From the Value sent for RADIUS attribute 11 (Filter-Id) drop-down list, specify what is sent for the attribute 11 (Filter-ID) value in RADIUS responses. You can choose to send the user's AuthPoint group or the user's Active Directory groups.
  4. In the Shared Secret text box, type the shared secret key that you specified in the Configure Microsoft NPS Server section. This is the password that the RADIUS server (AuthPoint Gateway) and the RADIUS client will use to communicate.
  5. To configure the RADIUS client resource to accept MS-CHAPv2 authentication requests, click the Enable MS-CHAPv2 toggle.
    Additional fields appear.

    If the L2TP VPN client is only used by local AuthPoint users, you do not have to enable MS–CHAPv2. Continue to Step 11.

  6. In the NPS RADIUS Server trusted IP or FQDN text box, type the IP address or fully qualified domain name (FQDN) of the NPS RADIUS server.
  7. In the Port text box, type 1812.

    If NPS and the Gateway are installed on the same server, the port that the Gateway uses to communicate with NPS must be different than the port that the Gateway uses to communicate with the RADIUS client.

  8. In the Timeout In Seconds text box, type 30.
  9. The screenshot of authpoint, picture 1

  10. Click Save.

Add an Access Policy to AuthPoint

You must have at least one user group in AuthPoint for authentication with the third-party IKEv2 or L2TP VPN client, and you must assign an access policy for the RADIUS client resource to that group. If you already have a group, you do not have to add another group.

In the AuthPoint management UI:

  1. From the navigation menu, select Groups.
  2. To add a new group, click Add Group. If you already have a group that you want to use, click the Name of your group to edit it.

  1. In the Name text box, type a descriptive name for the group.
  2. (Optional) In the Description text box, type a description of the group.

  1. In the Access Policy section, click Add Policy.

  1. In the Add Policy dialog box, from the Resource drop-down list, select the resource you want to add an access policy for.
  2. (Optional) To require that users type their password before they authenticate for this resource, select the Require Password Authentication toggle.
  3. Select the authentication options users in this group can choose from when they authenticate.

    For RADIUS resources, you can only choose OTP or Push. RADIUS resources cannot use the QR code authentication option.

  1. Click Add.
    The access policy for your resource is added to the list.

  1. Click Save.

Bind the RADIUS Resource to a Gateway

To use RADIUS authentication with AuthPoint, you must have the AuthPoint Gateway installed on your corporate network and you must assign your RADIUS resources to the Gateway in the AuthPoint management UI. The Gateway functions as a RADIUS server.

If you have not already configured and installed the AuthPoint Gateway, see About Gateways.

To assign your RADIUS resources to the Gateway:

  1. From the navigation menu, select Gateway.
  2. Select the Name of the Gateway.
  3. In the RADIUS section, in the Port text box, type the port number used to communicate with the Gateway. The default ports are 1812 and 1645.
  4. In the Select a RADIUS resource drop-down list, select your RADIUS client resource.
  5. Click Save.

Sync Users to AuthPoint from Active Directory

You must create AuthPoint user accounts for your users. To sync users from Active Directory, you must add an LDAP external identity and create one or more queries.

In AuthPoint, LDAP external identities represent external user databases. They connect to user databases to get user account information and validate passwords. The queries you add to an external identity specify which users to sync from your Active Directory or LDAP database. They pull user information and create AuthPoint user accounts for the users that are found.

For detailed instructions to sync users from Active Directory, see Sync Users from Active Directory or LDAP.

Test the Integration

To test AuthPoint MFA, you can authenticate with a mobile token on your mobile device. For RADIUS resources with MS-CHAPv2 enabled, you authenticate with a push notification (you receive a push notification in the mobile app that you must approve to authenticate).

  1. From a Windows 10 computer, select Settings.
  2. Select Network & Internet.
  3. Select VPN.
  4. Click Add a VPN connection.
    The Add a VPN connection window opens.
  5. From the VPN provider drop-down list, select Windows (built-in).
  6. In the Connection name text box, type a name. In our example, we type l2tp.
  7. In the Server name or address text box, type the FortiGate WAN port IP address.
  8. From the VPN type drop-down list, select L2TP/IPsec with pre-shared key.
  9. In the Pre-shared key text box, type the pre-shared key. This must be the same pre-shared key that you configured in the Configure L2TP VPN section.
  10. From the Type of sign-in info drop-down list, select User name and password.
  11. Click Save.
    The Add a VPN connection window closes.
  12. Select the VPN you created. Click Connect.
  13. Type your user name and password.
  14. Approve the authentication request that is sent to your mobile device.
    The VPN connects successfully.
  15. Screenshot of Win10