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NetMotion Mobility XE

Last Updated: September 11th, 2019


Duo integrates with your NetMotion Mobility VPN software to add two-factor authentication to any VPN login.


Duo two-factor authentication for NetMotion supports using the EAP (PEAP-GTC) mechanism against a RADIUS server using Duo's Authentication Proxy radius_client primary authentication or against an Active Directory domain controller using Duo's ad_client primary authentication. If you are not using Active Directory and do not have a RADIUS server that supports EAP you must deploy one (for example, Microsoft Network Policy Server or FreeRADIUS) before using Duo authentication. If using RADIUS as the primary authenticator with NetMotion EAP, the RADIUS server must permit use of PAP encryption.

You will need a certificate and corresponding key file when configuring the Duo Authentication Proxy. The key file must not be encrypted nor can it require a password for use. The certificate can be issued by a trusted certificate authority (CA) or self-signed. If you'd like to use a self-signed certificate, you can create one using OpenSSL following the example instructions here. If you have enabled the "Validate server certificate" option on your NetMotion Mobility clients, then you must use a certificate issued by a CA that your Mobility client systems trust.

This configuration doesn't support inline self-service enrollment. You'll need to create your users in Duo ahead of time using one of our other enrollment methods, like directory sync or CSV import. Read the enrollment documentation to learn more.

Connectivity Requirements

This application communicates with Duo's service on TCP port 443. Firewall configurations that restrict outbound access to Duo's service with rules using destination IP addresses or IP address ranges aren't recommended, since these may change over time to maintain our service's high availability. If your organization requires IP-based rules, please review this Duo KB article.

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 NetMotion VPN users before you begin to deploy Duo.

Next, locate (or set up) a system on which you will install the Duo Authentication Proxy. The proxy supports these operating systems:

  • Windows Server 2012 or later (Server 2016 or 2019 recommended)
  • CentOS 7 or later
  • Red Hat Enterprise Linux 7 or later
  • Ubuntu 16.04 or later
  • Debian 7 or later.

Then you'll need to:

  1. Sign up for a Duo account.
  2. Log in to the Duo Admin Panel and navigate to Applications.
  3. Click Protect an Application and locate NetMotion Mobility 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.
Treat your secret key like a password

The security of your Duo application is tied to the security of your secret key (skey). Secure it as you would any sensitive credential. Don't share it with unauthorized individuals or email it to anyone under any circumstances!

Install the Duo Authentication 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).

  1. Download the most recent Authentication Proxy for Windows from Note that the actual filename will reflect the version e.g. duoauthproxy-4.0.1.exe. View checksums for Duo downloads here.
  2. Launch the Authentication Proxy installer on the target Windows server as a user with administrator rights and follow the on-screen prompts.
  1. Ensure that Perl and a compiler toolchain are installed. On most recent RPM-based distributions — like Fedora, RedHat Enterprise, and CentOS — you can install these by running (as root):

    $ yum install gcc make libffi-devel perl zlib-devel

    On Debian-derived systems, install these dependencies by running (as root):

    $ apt-get install build-essential libffi-dev perl zlib1g-dev
  2. Download the most recent Authentication Proxy for Unix from Depending on your download method, the actual filename may reflect the version e.g. duoauthproxy-4.0.1-src.tgz. View checksums for Duo downloads here.

  3. Extract the Authentication Proxy files and build it as follows:

    $ tar xzf duoauthproxy-latest-src.tgz
    $ cd duoauthproxy-version-src
    $ make
  4. Install the authentication proxy (as root):

    $ cd duoauthproxy-build
    $ ./install

    Follow the prompts to complete the installation. The installer creates a user to run the proxy service and a group to own the log directory and files. You can accept the default user and group names or enter your own.

If you ever need to uninstall the proxy, run /opt/duoauthproxy/uninstall.

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:

Platform Default Configuration Path
Windows (64-bit) C:\Program Files (x86)\Duo Security Authentication Proxy\conf\authproxy.cfg
Windows (32-bit) C:\Program Files\Duo Security Authentication Proxy\conf\authproxy.cfg
Linux /opt/duoauthproxy/conf/authproxy.cfg
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:


Individual properties beneath a section appear as:


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. 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. In most cases, this means configuring the Proxy to communicate with Active Directory or RADIUS.

Active Directory

To use Active Directory/LDAP as your primary authenticator, add an [ad_client] section to the top of your config file. Add the following properties to the section:



The hostname or IP address of your domain controller.


The username of a domain account that has permission to bind to your directory and perform searches. We recommend creating a service account that has read-only access.


The password corresponding to service_account_username. If you're on Windows and would like to encrypt this password, see Encrypting Passwords in the full Authentication Proxy documentation.


The LDAP distinguished name (DN) of an Active Directory container or organizational unit (OU) containing all of the users you wish to permit to log in. For example:




The hostname or IP address of a secondary/fallback domain controller. You can add additional domain controllers as host_3, host_4, etc.


To further restrict access, specify the LDAP distinguished name (DN) of a security group that contains the users who should be able to log in as direct group members. Nested groups are not supported. Users who are not direct members of the specified group will not pass primary authentication. Example:


Starting with Authentication Proxy v3.2.0, the security_group_dn may be the DN of an AD user's primarygroup. Prior versions do not support primary groups.

For example:


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


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:



The IP address of your RADIUS server. You can add backup servers with host_2, host_3, etc.


A secret to be shared between the Authentication Proxy and your existing RADIUS server. If you're on Windows and would like to encrypt this secret, see Encrypting Passwords in the full Authentication Proxy documentation.



The authentication port on your RADIUS server. Use port_2, port_3, etc. to specify ports for the backup servers.



If this option is set to true, all RADIUS attributes set by the primary authentication server will be copied into RADIUS responses sent by the proxy.

Default: false

For example:


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 NetMotion Mobility

Next, you need to set up the Authentication Proxy to work with your NetMotion Mobility. Create a [radius_server_eap] section and add the properties listed below. If you've already set up the Duo Authentication Proxy for a different RADIUS EAP application, append a number to the section header to make it unique, like [radius_server_eap2].



Your integration key.


Your secret key.


Your API hostname (e.g. "").


The IP address of your NetMotion Mobility.


A secret to be shared between the proxy and your NetMotion Mobility. If you're on Windows and would like to encrypt this secret, see Encrypting Passwords in the full Authentication Proxy documentation.


The mechanism that the Authentication Proxy should use to perform primary authentication. This should correspond with a "client" section elsewhere in the config file.


Use Active Directory/LDAP for primary authentication. Make sure you have an [ad_client] section configured.


Use RADIUS for primary authentication. Make sure you have a [radius_client] section configured.

This parameter is optional if you only have one "client" section. If you have multiple, each "server" section should specify which "client" to use.


Path to PEM-formatted SSL/TLS server certificate. Both certs and pkey must be specified.


Path to PEM-formatted SSL/TLS private key that corresponds with the cert. The key file must not be protected by a password. Both cert and pkey must be specified.



The port on which to listen for incoming RADIUS Access Requests. If you have multiple RADIUS server sections you should use a unique port for each one.

Default: 1812.


Either "safe" or "secure":


In the event that Duo's service cannot be contacted, users' authentication attempts will be permitted if primary authentication succeeds. This is the default.


In the event that Duo's service cannot be contacted, all users' authentication attempts will be rejected.


If "false", always use auto-factor selection (never check for a delimiter in user passwords). Default: "true" (do check for the delimiter and an appended Duo factor or passcode).


The IP address of your second NetMotion Mobility, if you have one. You can specify additional devices as as radius_ip_3, radius_ip_4, etc.


The secrets shared with your second NetMotion Mobility, if using one. You can specify secrets for additional devices as radius_secret_3, radius_secret_4, etc. If you're on Windows and would like to encrypt this secret, see Encrypting Passwords in the full Authentication Proxy documentation.


Specify the minimum TLS version for SSL connections when the Authentication Proxy acts as a server. One of: "ssl3", "tls1.0", "tls1.1", or "tls1.2".

If not specified, defaults to TLS 1.2 as the minimum as of Authentication Proxy version 3.0.0. Configurable in version 2.12.0 or later.


If configured, this limits the SSL cipher suites used by the Authentication Proxy when acting as a server to the specific ciphers listed. Include an individual cipher name or group of ciphers using the OpenSSL cipher list format. See the Mozilla TLS Recommended configurations for more information.

If not specified, any valid cipher suite is allowed. Requires Authentication Proxy version 2.12.0 or later.

A completed config file, using Active Directory as the primary authenticator, should look something like:


Make sure to save your configuration file when done.


View video guides for proxy deployment at the Authentication Proxy Overview or see the Authentication Proxy Reference Guide for additional configuration options.

Start the Proxy

Open an Administrator command prompt and run:

net start DuoAuthProxy

Alternatively, open the Windows Services console (services.msc), locate "Duo Security Authentication Proxy Service" in the list of services, and click the Start Service button.

If the service starts successfully, Authentication Proxy service output is written to the authproxy.log file, which can be found in the log subdirectory.

If you see an error saying that the "service could not be started", open the Application Event Viewer and look for an Error from the source "DuoAuthProxy". The traceback may include a "ConfigError" that can help you find the source of the issue.

Stop and restart the Authentication Proxy service by either clicking the Restart Service button in the Windows Services console or issuing these commands from an Administrator command prompt:

net stop DuoAuthProxy & net start DuoAuthProxy

Open a root shell and run:

# /opt/duoauthproxy/bin/authproxyctl start

To ensure the proxy started successfully, run:

# /opt/duoauthproxy/bin/authproxyctl status

Authentication Proxy service output is written to the authproxy.log file, which can be found in the log subdirectory.

To stop and restart the Authentication Proxy, open a root shell and run:

# /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.

Configure NetMotion Mobility Server

Set User Authentication Protocol to RADIUS EAP

  1. Log in to the Mobility administrative interface.
  2. Under the Configure tab, navigate to Authentication Settings.
  3. Choose the Authentication - Protocol setting.
  4. Select RADIUS - EAP (PEAP and EAP-TLS).

    Radius Protocol

  5. Click Apply.

Set RADIUS Retransmit Interval

  1. Choose the RADIUS: Device Authentication - Retransmit Interval setting.
  2. Enter an interval long enough for a user's mobile device to receive and respond to Duo authentication requests. Recommended: at least 40000 milliseconds. If Mobility retransmits an authentication request while the Duo Authentication Proxy is waiting for the second factor it will be detected as an attempt to replay a login already in progress and rejected.

    RADIUS Retransmit Interval

  3. Click Apply.

Add RADIUS server

  1. Choose the RADIUS: User Authentication - Servers setting.

    RADIUS Server List

  2. Add the Duo Authentication Proxy. Enter its IP and the port and shared secret from the radius_server_eap section of your authproxy.cfg and click OK.

    RADIUS Server Add

  3. Remove any other RADIUS servers from the list to ensure that Duo authentication is always used.

Test Your Setup

  1. Launch the Mobility client and log in with your username and password as you normally would.

    Mobility Client Primary Credentials

  2. Next, enter your Duo passcode or an out-of-band factor into the following prompt and click OK. You may choose from the following factor names:

    push Perform Duo Push authentication
    You can use Duo Push if you've installed Duo Mobile and added your account to it
    phone Perform phone callback authentication
    sms Send a new batch of SMS passcodes
    You will be prompted again to enter one of the newly-delivered passcodes.

    Mobility Client Duo Challenge

  3. Duo will send you a push, phone call, or SMS and log you in.


Need some help? Take a look at our NetMotion Knowledge Base articles or Community discussions. For further assistance, contact Support.

Network Diagram

  1. Primary authentication initiated to NetMotion Mobility
  2. NetMotion Mobility 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. NetMotion Mobility access granted