Cisco ASA L2TP VPN Integration with AuthPoint

Deployment Overview

This document describes how to set up AuthPoint multi-factor authentication (MFA) for Active Directory users that use Cisco® ASA (Adaptive Security Appliance) with an L2TP VPN client.

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

Integration Summary

The hardware and software used in this guide include:

  • Cisco ASA 5506 v9.14(1)
  • AuthPoint Gateway v5.3.1.184 or higher
  • Windows Server 2016 with Microsoft Network Policy Server (NPS) and Active Directory Domain Services

Cisco ASA Configuration for RADIUS Authentication

AuthPoint communicates with various cloud-based services and service providers with the RADIUS protocol. This diagram shows an overview of the configuration required for RADIUS authentication.

Topology diagram

Before You Begin

Before you begin these procedures, make sure that:

  • 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.

  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 Cisco ASA Unit

Follow these steps to configure the Cisco ASA unit.

Add the AuthPoint Gateway to the AAA Server Groups

  1. Start Cisco Adaptive Security Device Manager (ASDM) and log in to Cisco ASA.
  2. Select Configuration.
  3. Select Device Management > Users/AAA > AAA Server Groups.
  4. Screenshot of the RADIUS server

  5. Next to the AAA Server Groups section, click Add.
    The Add AAA Server Group window appears.
  6. In the AAA Server Group text box, type a name for the server group. In our example, we type AuthPointGroup.
  7. Screenshot of the RADIUS server

  8. Click OK to save the AAA server group. Leave the default value for other settings.
  9. From the AAA Server Groups list, select the AAA Server group you created.
  10. Screenshot of the RADIUS server

  11. Next to the Servers in the Selected Group section, click Add to add an AAA Server for the selected AAA Server group.
    The Add AAA Server window appears.
  12. From the Interface Name drop-down list, select opt1. This is the interface for connections to the AuthPoint Gateway.
  13. In the Server Name or IP Address text box, type the IP address of the AuthPoint Gateway.
  14. In the Timeout text box, type 60.
  15. In the Server Authentication Port text box, type 1812.
  16. In the Server Accounting Port text box, type 1813.
  17. In the Server Secret key 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 (Cisco ASA) will use to communicate.

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

  18. Screenshot of the RADIUS server

  19. Click OK to save the AAA Server settings.
  20. Click Apply.

    Screenshot of the configured RADIUS server

Configure the L2TP VPN Address Pool

  1. Select Configuration.
  2. Select Remote Access VPN > Network (Client) Access > Address Assignment > Address Pools.
  3. Click Add > IPv4 Address Pool.
    The Add IPv4 Pool window appears.
  4. In the Name text box, type a name.
  5. In the Starting IP Address text box, type the start IP address.
  6. In the Ending IP Address text box, type the ending IP address.
  7. In the Subnet Mask text box, type the subnet mask.
  8. Screenshot of Add l2tp vpn pool

  9. Click OK.
  10. Click Apply.
  11. Screenshot of Add l2tp vpn pool

Configure L2TP VPN

  1. Select Wizards > VPN Wizards > IPSec (IKEv1) Remote Access VPN Wizard.
  2. Screenshot of L2TP VPN setup

  3. From the VPN Tunnel Interface drop-down list, select outside. This is the external interface of the Cisco ASA unit.
  4. Click Next.

    Screenshot of the Configure L2TP VPN 2.jpg

  1. Click Next.
  2. For VPN Client Type, select Microsoft Windows client using L2TP over IPsec.
  3. Select the MS-CHAP-V2 check box.
  4. Screenshot of the Configure L2TP VPN

  5. Click Next.
  6. Select Pre-Shared Key.
  7. In the Pre-Shared Key text box, type a pre-shared key. You must specify this same key when you configure the VPN client.
  8. Screenshot that shows the VPN Creation Wizard completed

  9. Click Next.
  10. Select Authenticate using an AAA server group.
  11. From the AAA Server Group Name drop-down list, select the group you created in the previous section.
  12. Screenshot that shows the Configure L2TP VPN

  13. Click Next.
  14. From the Pool Name drop-down list, select the pool you created in the previous section.
  15. Screenshot that shows the Configure L2TP VPN

  16. Click Next.
  17. In the Primary DNS Server and Secondary DNS Server text box, type the IP address of the DNS server.
  18. Screenshot that shows the Configure L2TP VPN

  19. Click Next.
  20. From the Interface drop-down list, select opt1.
  21. In the Exempt Networks, add opt1-network/24.
  22. Screenshot that shows the Configure L2TP VPN

  23. Select Enable split tunneling to let remote users have simultaneous encrypted access to resources defined above, and unencrypted access to the internet.
  24. Select Enable Perfect Forwarding Secrecy (PFS).
  25. From the Diffie-Hellman Group drop-down list, select 1.
  26. Screenshot that shows the Configure L2TP VPN

  27. Click Next.
  28. Click Finish.
  29. Click Save.

Configure Firewall ACL

  1. Select Configuration.
  2. Select Firewall > Advanced > ACL Manager.
  3. Click +Add > Add ACL.
    The Add ACL window appears.
  4. Screenshot that shows the Configure ACL

  5. In the ACL Name text box, type a name of the ACL. The ACL name must match the Filter-id you set in the Connection Request Policies Settings in your NPS server.
  6. Screenshot that shows the Configure NPS server

  7. Click OK.
  8. Select the ACL you just created.
  9. Click +Add > Add ACE.
    The Add ACE window appears.
  10. Select Permit.
  11. From the Source and Destination drop-down lists, select any.
  12. From the Service drop-down list, select ip. You can choose to select another service to use if you want.
  13. Screenshot that shows the Configure add ACE

  14. Click OK. Leave the default value for other settings.
  15. Click Apply.
  16. Screenshot that shows the Configure add ACL

Configure AuthPoint

Before AuthPoint can receive authentication requests from your Cisco ASA 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. Click the Enable MS-CHAPv2 toggle.
    Additional fields appear.
  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 60.
  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, 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 Cisco ASA 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