Duo Two-Factor Authentication for Palo Alto GlobalProtect RADIUS

Overview

Duo authentication for Palo Alto GlobalProtect supports push, phone call, or passcode authentication for GlobalProtect desktop and mobile client connections using RADIUS. This configuration does not feature the interactive Duo Prompt for web-based logins. After submitting primary username and password, users automatically receive a login request via Duo Push notification to a mobile device or as a phone call.

If you need inline self-service enrollment and the Duo Prompt for GlobalProtect SSO logins, refer to the Duo Single Sign-On for Palo Alto GlobalProtect instructions.

Learn more about the differences between these two Palo Alto GlobalProtect deployment configurations.

Walkthrough Video

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, and Duo policy settings and how to apply them. You'll need to pre-enroll your users in Duo using one of our available methods before they can log in using this configuration. See all Duo Administrator documentation.

You should already have a working primary authentication configuration for your Palo Alto users before you begin to deploy Duo.

To integrate Duo with your Palo Alto, 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 Palo Alto, contact your existing local LDAP/AD or RADIUS server to perform primary authentication if necessary, 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 Palo Alto SSL VPN 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 Your Primary Authenticator

In this step, you'll set up the Proxy's primary authenticator — the system which will validate users' existing passwords. Determine which type of primary authentication you'll be using, and create either an Active Directory/LDAP [ad_client] client section, or a RADIUS [radius_client] section as follows.

Active Directory

Add an [ad_client] section if you'd like to use an Active Directory domain controller (DC) or LDAP-based directory server to perform primary authentication. This section accepts the following options:

Required

search_dn=DC=example,DC=com

Optional

security_group_dn=CN=DuoVPNUsers,OU=Groups,DC=example,DC=com

For example:

[ad_client]
host=1.2.3.4
host_2=1.2.3.5
service_account_username=duoservice
service_account_password=password1
search_dn=DC=example,DC=com
security_group_dn=CN=DuoVPNUsers,OU=Groups,DC=example,DC=com

For advanced Active Directory configuration, see the full Authentication Proxy documentation.

RADIUS

To use RADIUS as your primary authenticator, add a [radius_client] section to the top of your config file. Then add the following properties to the section:

Required

Optional

For example:

[radius_client]
host=1.2.3.4
host_2=1.2.3.5
secret=radiusclientsecret

In addition, make sure that the RADIUS server is configured to accept authentication requests from the Authentication Proxy.

For advanced RADIUS configuration, see the full Authentication Proxy documentation.

Configure the Proxy for Your Palo Alto GlobalProtect

Next, we'll set up the Authentication Proxy to work with your Palo Alto GlobalProtect. Create a [radius_server_auto] section and add the properties listed below. If you've already set up the Duo Authentication Proxy for a different RADIUS Auto application, append a number to the section header to make it unique, like [radius_server_auto2].

Required

Optional

A completed config file that uses Active Directory should look something like:

[ad_client]
host=1.2.3.4
service_account_username=duoservice
service_account_password=password1
search_dn=cn=Users,dc=example,dc=com
 
[radius_server_auto]
ikey=DIXXXXXXXXXXXXXXXXXX
skey=XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
api_host=api-XXXXXXXX.duosecurity.com
radius_ip_1=5.6.7.8
radius_secret_1=radiussecret1
client=ad_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 Palo Alto GlobalProtect Gateway

Add the Duo RADIUS server

1. Log in to the Palo Alto administrative interface.

2. On the Device tab, navigate to Server Profiles, then RADIUS.

3. Click the Add button to add a new RADIUS server profile.

4. In the "Name" field, enter Duo RADIUS (or another descriptive name).

5. Increase the "Timeout" to at least 30 (60 recommended if using push or phone authentication).

6. Change the "Authentication Protocol" drop-down option to PAP.

   PAN-OS 7.x users must set the protocol in the CLI with this command:

   set authentication radius-auth-type pap

   See the PAN-OS documentation for more information.

7. Under the "Servers" section, click the Add button to add a RADIUS server, and enter the following information:

   Setting	Value
   Server	Type in Duo RADIUS or any name you prefer.
   RADIUS Server	The hostname or IP address of your Duo Authentication Proxy.
   Secret	The RADIUS shared secret used in the Authentication Proxy configuration.
   Port	1812 (or whichever port you configured on your Duo Authentication Proxy).

8. Click OK to save the new RADIUS server profile.

   

Add an Authentication Profile

1. On the Device tab, navigate to Authentication Profile.

2. Click the New... button to add a new authentication profile, and enter the following information:

   Setting	Value
   Name	Enter Duo or any name you prefer.
   Type	Select RADIUS from the drop-down list.
   Server Profile	Select Duo RADIUS from the drop-down list (or whatever name used to create the RADIUS Server Profile in the Add the Duo RADIUS Server section.
   User Domain	(Optional) Depending how your users log on to GlobalProtect you may need to enter your authentication domain name here. Used in conjunction with Username Modifier. Learn more about this setting in the GlobalProtect documentation.
   Username Modifier	(Optional) If this is blank (or set to %USERINPUT%) then the user's input is unmodified. You can prepend or append the value of User Domain (as %USERDOMAIN%) to pre-configure the username input. Learn more about this setting in the GlobalProtect documentation.

3. Click the Advanced tab. In the "Allow List" section click the drop-down and select the all group (or, if you want to restrict which users may authenticate with the Duo profile, select the group of your choice).

4. Click OK to save the authentication profile.

   

Configure GlobalProtect Gateway

1. On the Network tab, navigate to GlobalProtect then Gateways.

2. Click on your configured GlobalProtect Gateway to bring up the properties window.

3. On the Authentication tab of the GlobalProtect Gateway properties, select the Duo authentication profile created in Add an Authentication Profile from the available "Authentication Profile" selections for client authentication.

   

4. (Optional) If you aren't using authentication override cookies on your GlobalProtect Gateway already you may want to enable it to minimize Duo authentication requests at client reconnection during one gateway session. Refer to the GlobalProtect cookie authentication documentation to fully understand this feature before enabling it.

   Click the Agent tab on the left and then click the Client Settings tab. Click on the name of your config to open it.

5. (Optional) On the "Authentication Override" tab check the options to both generate and accept cookies for authentication override. Set a cookie lifetime and select a certificate to use with the cookie. Note that users will not need to repeat 2FA after their initial success when reconnecting during the cookie lifetime duration.

   

6. Click OK (twice if you also enabled authentication override cookies) to save the GlobalProtect Gateway settings.

Learn more about GlobalProtect gateway configuration in the PaloAlto GlobalProtect Admin Guide.

Configure GlobalProtect Portal

If the GlobalProtect Portal is configured for Duo two-factor authentication, users may have to authenticate twice when connecting the GlobalProtect Gateway Agent. For the best user experience, Duo recommends leaving your GlobalProtect Portal set to use LDAP or Kerberos authentication, or if you do add Duo to your GlobalProtect Portal that you also enable cookies for authentication override on your GlobalProtect portal to avoid multiple Duo prompts for authentication when connecting.

Note that if Duo is applied only at the GlobalProtect Gateway then users may not append a factor or passcode to their password when logging in.

If your organization would like to protect the GlobalProtect Portal with Duo follow these instructions.

1. On the Network tab, navigate to GlobalProtect then Portal.

2. Click on your configured GlobalProtect Portal to bring up the properties window.

3. On the Authentication tab of the GlobalProtect Portal Configuration, select the Duo authentication profile created in Add an Authentication Profile from the available "Authentication Profile" selections for client authentication.

   

4. (Optional) If you aren't using authentication override cookies on your GlobalProtect Portal already you may want to enable it to minimize Duo authentication requests at client reconnection during one session.

   Click the Agent tab on the left and then click on the name of your config to open it.

5. (Optional) On the "Authentication" tab check the options to both generate and accept cookies for authentication override. Set a cookie lifetime and select a certificate to use with the cookie.

   

6. Click OK (twice if you also enabled authentication override cookies) to save the GlobalProtect Portal settings.

Learn more about GlobalProtect gateway configuration in the PaloAlto GlobalProtect documentation.

Commit and Save Your Settings

To make your changes take effect, click the Commit button in the upper-right corner of the Palo Alto administrative interface. Once you've tested your setup, you can click Save to save the settings.

Client IP Reporting

When using Duo's radius_server_auto integration with the Palo Alto GlobalProtect Gateway clients or Portal access, Duo's authentication logs may show the endpoint IP as 0.0.0.0. Palo Alto does not send the client IP address using the standard RADIUS attribute Calling-Station-Id.

A new RADIUS attribute containing the client IP address (PaloAlto-Client-Source-IP) was introduced in PAN-OS v7. Duo's Authentication Proxy supports the PaloAlto-Client-Source-IP attribute as of version 2.4.12.

To send the PaloAlto-Client-Source-IP attribute information to Duo:

1. Connect to the PA device administration shell and enable sending the PaloAlto-Client-Source-IP client IP attribute:

   set authentication radius-vsa-on client-source-ip

2. When configuring the Authentication Proxy's [radius_server_auto] authproxy.cfg settings for your Palo Alto device include the following setting:

   client_ip_attr=paloalto

The client IP address is sent to the Authentication Proxy as AVP 19 and is captured in Duo's authentication log.

Test Your Setup

Navigate your browser to the GlobalProtect Portal page, or attempt to connect your GlobalProtect Gateway agent.

If you applied Duo to the GlobalProtect Gateway only:

To test your setup, attempt to log in to your newly-configured system as a user enrolled in Duo with an associated Duo Push or phone authentication device.

When you enter your username and password, you will receive an automatic push or phone callback.

If you applied Duo to both the GlobalProtect Gateway and Portal:

To test your setup, attempt to log in to your newly-configured system as a user enrolled in Duo with an authentication device.

When you enter your username and password, you will receive an automatic push or phone callback.

Alternatively you may add a comma (",") to the end of your password and append a Duo factor option:

For example, if you wanted to use a passcode to authenticate instead of Duo Push or a phone call, you would enter:

username: bob
password: hunter2,123456

If you wanted to use specify use of phone callback to authenticate instead of an automatic Duo Push request, you would enter:

username: bob
password: hunter2,phone

You can also specify a number after the factor name if you have more than one device enrolled (as the automatic push or phone call goes to the first capable device attached to a user). So you can enter phone2 or push2 if you have two phones enrolled and you want the authentication request to go to the second phone.

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 our Palo Alto Knowledge Base articles or Community discussions. For further assistance, contact Support.

Network Diagram

1. Primary authentication initiated to Palo Alto Global Protect
2. Palo Alto Global Protect sends authentication request to Duo Security’s authentication proxy
3. Primary authentication using Active Directory or RADIUS
4. Duo authentication proxy connection established to Duo Security over TCP port 443
5. Secondary authentication via Duo Security’s service
6. Duo Authentication Proxy receives authentication response
7. Palo Alto Global Protect access granted