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Set up Nexus OTP as 2FA for Citrix NetScaler

This article describes how to enable Nexus OTP in Smart ID Digital Access component as two-factor authentication method for Citrix NetScaler, to replace static passwords.

Nexus OTP can be either Nexus TruID Synchronized or Smart ID Mobile App OTP, or any other OATH-based mobile OTP application, such as Google Authenticator or Microsoft Authenticator.

With the setup described in this article, Digital Access functions as a RADIUS server and Citrix NetScaler as a RADIUS client. Nexus TruID is used as an example below and is available for iOS, Android, and Windows.

Network schematic for Nexus OTP authentication

Network schematic with Nexus TruID Synchronized as an example.


  1. The end user starts the TruID client and enters the PIN in TruID to generate an OTP.
  2. Citrix NetScaler requests the end user to enter username, password and OTP.
  3. The end user enters username, domain password and OTP.
  4. The domain credentials are validated by the Active Directory.
  5. The OTP authentication request is relayed to Digital Access Authentication Server via RADIUS.
  6. The authentication server validates the OTP with the associated TruID token and PIN from the user database.
  7. Upon successful validation, the authentication server responds with successful authentication to Citrix NetScaler.

Citrix NetScaler provides access to the end user.

Prerequisites

Make settings in Digital Access

Log in to Digital Access Admin
  1. Log in to Digital Access Admin with an administrator account.
Add Citrix NetScaler as a RADIUS client

In step 3, enter the IP Address of the RADIUS Client (Citrix NetScaler) and the Shared Secret Key.

  1. In Digital Access Admin, go to Manage System.
  2. Click RADIUS Configuration > Add RADIUS Client...
  3. Enter General Settings and Attributes. Click the ?-sign for help.
  4. Click Save.
Enable authentication method

Nexus TruID Synchronized is used as an example. Other Nexus OTP authentication methods are enabled in a similar way.

  • In step 3, select Nexus Synchronized as method.
  • When the default RADIUS replies are shown, click Next. You can also add your custom RADIUS replies or modify the default replies if required.

To add a new authentication method:

  1. In Digital Access Admin, go to Manage System.
  2. Click Authentication Methods.
  3. Click Add authentication method..., select the desired method and click Next.

  4. Enter Display Name, a unique name used in the system to identify the authentication method.
  5. Select if the method shall be enabled and if it shall be visible in authentication menu.
  6. Register Authentication Methods Server when applicable.
  7. Make other configurations as needed for the selected authentication method. For more information , click the ?-sign. Click Next.
  8. If needed, make settings in RADIUS Replies and Extended Properties.
  9. Click Next and Finish.
  10. Click Publish.

Make settings in Citrix NetScaler

Add Digital Access as RADIUS Server
  1. Log in to the Citrix NetScaler administrative interface.
  2. Navigate to Access Gateway > Virtual Servers in the left panel of the administrative interface.

  3. Select your existing Access Gateway Virtual Server, and then click Open.

  4. In the Configure Access Gateway Virtual Server dialog, select the Authentication tab.

  5. Below Authentication Policies, select Primary and then click Insert Policy.

  6. In the Configure Authentication Policy page enter “Nexus RADIUS” as Name.

  7. In the Named Expressions section select General in the first drop down, and True Value in the
    second drop down.

  8. Click Add Expression.

  9. Click New… next to Server drop down.
  10. Enter the following information in the Configure Authentication Server window:

    1. Name: Nexus RADIUS

    2. IP Address: The IP address of Digital Access Authentication Server

    3. Secret Key: The RADIUS shared secret key

    4. Confirm Secret Key: Confirm the RADIUS shared Secret Key

  11. Click OK to add the RADIUS server.
  12. Click OK to save the new authentication policy.
  13. Click OK to save the changes made to the Virtual Server.

Example: Log in to Citrix NetScaler

The following example shows how an end user logs in, using Nexus TruID synchronized. Other Nexus OTP methods can be used in a similar way. 

Example: Use Nexus TruID as 2FA to log in to Citrix NetScaler
  1. Start Nexus TruID that is installed on your laptop or smartphone - Enter your PIN to generate an OTP.

  2. Enter Key-In domain login id and password along with Nexus TruID OTP.

Related information

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