F5 BIG-IP APM with RADIUS and Duo Prompt

The Duo F5 Big-IP configuration with inline enrollment and Duo Prompt supports firmware versions 11.4 and later when using Standard Customization only. The Duo Prompt over RADIUS is not supported in the Modern Customization type available in v15.1 and later. Ensure your BIG-IP has all current updates for your platform version.

Refer to our alternate RADIUS instructions if you want to configure Duo on your BIG-IP with automatic push and phone call authentication.

First Steps

Before moving on to the deployment steps, it's a good idea to familiarize yourself with Duo administration concepts and features like options for applications, available methods for enrolling Duo users, and Duo policy settings and how to apply them. See all Duo Administrator documentation.

You should already have a working primary authentication configuration for your F5 BIG-IP APM users before you begin to deploy Duo.

To integrate Duo with your F5 BIG-IP APM, you will need to install a local Duo proxy service on a machine within your network. This Duo proxy server will receive incoming RADIUS requests from your F5 BIG-IP APM and then contact Duo's cloud service for secondary authentication.

If you are already running a Duo Authentication Proxy server in your environment, you can use that existing host for additional applications, appending the new configuration sections to the current config. You don't have to set up a new Authentication Proxy server for each application you create. However, there are some cases where it might make sense for you to deploy a new proxy server for a new application, like if you want to co-locate the Duo proxy with the application it will protect in the same data center.

We recommend the following 64-bit operating systems for the system hosting the Duo Authentication Proxy:

• Windows Server 2016 or later
• CentOS Stream 9 or later
• Fedora 39 or later
• Red Hat Enterprise Linux 7 or later
• Rocky Linux 9 or later
• Ubuntu 20.04 LTS or later
• Debian 11 or later

The Duo End of Sale, Last Date of Support, and End of Life Policy states that Duo does not offer support for integrations running on operating system versions beyond the vendor’s stated Last Date of Support date.

See detailed Authentication Proxy operating system performance recommendations in the Duo Authentication Proxy Reference.

We do not recommend installing the Duo Authentication Proxy on the same Windows server that acts as your Active Directory domain controller or one with the Network Policy Server (NPS) role. If you must co-locate the Duo Authentication Proxy with these services, be prepared to resolve potential LDAP or RADIUS port conflicts between the Duo service and your pre-existing services.

Then you'll need to:

1. Sign up for a Duo account.
2. Log in to the Duo Admin Panel and navigate to Applications → Protect an Application.
3. Locate the entry for F5 BIG-IP APM with a protection type of "2FA" in the applications list. Click Protect to get your integration key, secret key, and API hostname. You'll need this information to complete your setup. See Protecting Applications for more information about protecting applications in Duo and additional application options.

Install the Duo Authentication Proxy

If you will reuse an existing Duo Authentication Proxy server for this new application, you can skip the install steps and go to Configure the Proxy.

The Duo Authentication Proxy can be installed on a physical or virtual host. We recommend a system with at least 1 CPU, 200 MB disk space, and 4 GB RAM (although 1 GB RAM is usually sufficient). See additional Authentication Proxy performance recommendations in the Duo Authentication Proxy Reference.

We do not recommend installing the Duo Authentication Proxy on the same Windows server that acts as your Active Directory domain controller or one with the Network Policy Server (NPS) role. If you must co-locate the Duo Authentication Proxy with these services, be prepared to resolve potential LDAP or RADIUS port conflicts between the Duo service and your pre-existing services.

duoauthproxy-version.exe /S

duoauthproxy-version.exe /S /exclude-auth-proxy-manager

sudo ./duoauthproxy-build/install --install-dir /opt/duoauthproxy --service-user duo_authproxy_svc --log-group duo_authproxy_grp --create-init-script yes

Configure the Proxy

After the installation completes, you will need to configure the proxy.

The Duo Authentication Proxy configuration file is named authproxy.cfg, and is located in the conf subdirectory of the proxy installation. With default installation paths, the proxy configuration file will be located at:

Note that as of v4.0.0, the default file access on Windows for the conf directory is restricted to the built-in Administrators group during installation.

The configuration file is formatted as a simple INI file. Section headings appear as:

[section]

Individual properties beneath a section appear as:

name=value

The Authentication Proxy may include an existing authproxy.cfg with some example content. For the purposes of these instructions, however, you should delete the existing content and start with a blank text file.

Duo Authentication Proxy Manager

The Duo Authentication Proxy Manager is a Windows utility for managing the Authentication Proxy installation on the Windows server where you install the Authentication Proxy. The Proxy Manager comes with Duo Authentication Proxy for Windows version 5.6.0 and later.

The Proxy Manager cannot manage remote Duo Authentication Proxy servers, nor can you install the Proxy Manager as a stand-alone application. There is no Proxy Manager available for Linux. The Proxy Manager only functions as part of a local Duo Authentication Proxy installation on Windows servers.

Learn more about using the Proxy Manager in the Duo Authentication Proxy Reference before you continue.

To launch the Proxy Manager utility:

• Open the Start Menu and go to Duo Security.
• Click the Duo Authentication Proxy Manager icon to launch the application. You must have administrative privileges on the Windows server and accept the prompt for elevation.
• The Proxy Manager launches and automatically opens the %ProgramFiles%\Duo Security Authentication Proxy\conf\authproxy.cfg file for editing.

Use the Proxy Manager editor on the left to make the authproxy.cfg changes in these instructions. As you type into the editor, the Proxy Manager will automatically suggest configuration options. Accepting these suggestions helps make sure you use the correct option syntax.

As you follow the instructions on this page to edit the Authentication Proxy configuration, you can click Validate to verify your changes (output shown on the right).

When you complete the Authentication Proxy configuration steps in this document, you can use the Save button to write your updates to authproxy.cfg, and then use the authproxy.cfg button to start the Authentication Proxy service before continuing on to the next configuration steps.

If you do not use the Proxy Manager to edit your configuration then we recommend using WordPad or another text editor instead of Notepad when editing the config file on Windows.

Configure the Proxy for Duo Only Authentication

At the top of your authproxy.cfg, create a [duo_only_client] section. This section has no additional parameters to configure.

[duo_only_client]

When using the [duo_only_client] configuration, the Authentication Proxy will ignore primary credentials and perform Duo factor authentication only.

Configure the Proxy for Your F5 BIG-IP APM

Next, we'll set up the Authentication Proxy to work with your F5 BIG-IP APM. Create a [radius_server_iframe] section and add the properties listed below. If you've already set up the Duo Authentication Proxy for a different RADIUS iframe application, append a number to the section header to make it unique, like [radius_server_iframe2].

Required

Optional

A completed config file, with the Authentication Proxy only performing secondary authentication, should look something like:

[duo_only_client]
 
[radius_server_iframe]
type=f5_bigip
ikey=DIXXXXXXXXXXXXXXXXXX
skey=XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
api_host=api-XXXXXXXX.duosecurity.com
radius_ip_1=5.6.7.8
radius_secret_1=radiussecret1
client=duo_only_client
port=1812
failmode=safe

Make sure to save your configuration file in your text editor — or validate and save in the Proxy Manager for Windows — when you're finished making changes.

Start the Proxy

net start DuoAuthProxy

authproxyctl start

net stop DuoAuthProxy & net start DuoAuthProxy

authproxyctl restart

# /opt/duoauthproxy/bin/authproxyctl start

# /opt/duoauthproxy/bin/authproxyctl status

# /opt/duoauthproxy/bin/authproxyctl restart

If you modify your authproxy.cfg configuration after initial setup, you'll need to stop and restart the Duo Authentication Proxy service or process for your change to take effect.

You can view information about your Authentication Proxy in the Authentication Proxy Dashboard.

Configure Your F5 BIG-IP APM

1. Log into the BIG-IP management console and navigate to Access Policy → AAA Servers → RADIUS and click the Create button.

   Enter a name for your new Duo RADIUS server. Set the Mode to "Authentication" and fill in the host/port/secret information that corresponds to your Duo Authentication Proxy configuration. Be sure to increase the timeout to 60 seconds and set the character set to utf-8.

   

2. You'll need to modify an existing Access Policy to use the newly defined Duo RADIUS server for authentication (or create a new one). Navigate to Access Policy → Access Profiles → Access Profiles List and click the Edit... link in the Access Policy column of the profile you want to update to use Duo.

   Use the Access Policy editor to insert the Duo RADIUS authentication method after success with your current authentication method (like AD/LDAP). Click the plus symbol in the "Successful" arrow coming off your primary authenticator and type "RADIUS" in the search field on the subsequent page. Select RADIUS Auth and click Add Item.

   On the RADIUS Auth properties tab select your Duo RADIUS system in the AAA Server drop-down and click Save.

   

   Your policy now shows two authenticators (your original method followed by RADIUS).

   In this example, Duo RADIUS authentication has been added to an existing Access Policy after successful primary AD authentication.

   

   Click Close to exit the Access Policy editor and return to the Access Profile List page. The profile you just modified may have a yellow status flag. Click the checkbox next to that policy to select it and then click Apply Access Policy. The status flag will turn green.

   Consult the BIG-IP Access Policy Manager Configuration Guide for more information about creating and modifying Access Policies or contact F5 support.

3. Navigate to Access Policy → Customization → Advanced and change the "Edit Mode" to Advanced. Navigate through the Access Profiles tree to the Common folder beneath your Access Policy.

4. Add the Duo script, using the instructions for your BIG-IP firmware version:

   • v11.5 and greater
   • v11.4

   Click on the header.inc item and then insert the following JS snippet at the end of the Advanced Customization Editor Footer text input box and click Save:

   <script src="https://api-XXXXXXXX.duosecurity.com/frame/hosted/Duo-F5-BIG-IP-v2.js"></script>

   

   Click on the footer.inc item and then insert the following JS snippet at the end of the Advanced Customization Editor Footer text input box and click Save:

   <script src="https://api-XXXXXXXX.duosecurity.com/frame/hosted/Duo-F5-BIG-IP-v2.js"></script>

   

5. While still in Access Policy Advanced Customization Editor, navigate through the Access Profiles tree to Access Policy > Logon Pages > Logon Page folder beneath your Access Policy.

   Click the logon.inc item and locate the <head> section of the page in the Advanced Customization Editor (around line 90):

   Add this line to the <head> section after the first meta http-equiv line and click Save:

   <meta http-equiv="X-UA-Compatible" content="IE=Edge" />

   

Save the customization changes and return to the Access Profile List page. The profile you just modified may have a yellow status flag. Click the checkbox next to that policy to select it and then click Apply Access Policy. The status flag will turn green.

Test Your Setup

To test your setup, go to the URL you normally use to log in to your F5 BIG-IP APM in a browser window. After you complete primary authentication, the Duo Prompt or enrollment page appears.

The BIG-IP Edge Client also supports authentication with the Duo Prompt.

Troubleshooting

Need some help? Review troubleshooting tips for the Authentication Proxy and try the connectivity tool included with Duo Authentication Proxy 2.9.0 and later to discover and troubleshoot general connectivity issues.

Also take a look at the F5 BIG-IP Frequently Asked Questions (FAQ) page or try searching our F5 BIG-IP Knowledge Base articles or Community discussions. For further assistance, contact Support.

Network Diagram

1. Primary authentication initiated to F5 BIG-IP APM
2. F5 BIG-IP APM verifies primary logon credentials with external directory using Active Directory or RADIUS
3. F5 BIG-IP APN sends authentication request to Duo Security’s authentication proxy
4. Duo authentication proxy connection established to Duo Security over TCP port 443
5. User completes Duo two-factor authentication via the interactive web prompt served from Duo's service and their selected authentication factor.
6. Duo Authentication Proxy receives authentication response
7. F5 BIG-IP APM access granted