Prerequisites

To protect Amazon WorkSpaces logins with Duo you must be using an AD Connector type directory. The AWS Simple AD directory type does not support multifactor authentication.

View your directory in the WorkSpaces Management Console to obtain the Directory IP addresses. You will need them to configure the Duo Authentication Proxy.

You'll also need to enroll your WorkSpaces users in Duo before they can use multifactor authentication.

First Steps

To integrate Duo with Amazon WorkSpaces, you will need to install a Duo RADIUS authentication proxy service on one or more EC2 instances in an AWS VPC, or on one or more machines in an on-premise environment. Before proceeding, you should locate (or set up) a system on which you will install the Duo Authentication Proxy. The proxy supports Windows and Linux systems (in particular, we recommend Windows Server 2012 R2 or later, Red Hat Enterprise Linux 6, CentOS 6, Debian 6, or Amazon Linux 2015.03 or later).

It is highly recommended that you assign a fixed private IP to your Authentication Proxy machine, as the WorkSpaces MFA configuration contacts the RADIUS server by IP address.

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 RADIUS in the applications list. Click Protect this Application to get your integration key, secret key, and API hostname. (See Getting Started for help.)

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).

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 located in the conf subdirectory of the proxy installation. With default installation paths, the proxy configuration file will be located at:

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. 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 AWS Directory

Next, you need to set up the Authentication Proxy to work with your AWS WorkSpaces Directory. To do so, create a radius_server_duo_only section with the following properties:

Required

Optional

A completed config file for AWS WorkSpaces using radius_server_duo_only with no primary authenticator should look something like:

[duo_only_client]
 
[radius_server_duo_only]
ikey=DIXXXXXXXXXXXXXXXXXX
skey=XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
api_host=api-XXXXXXXX.duosecurity.com
failmode=safe
radius_ip_1=10.20.10.10
radius_secret_1=theradiussecret
radius_ip_2=10.20.11.10
radius_secret_2=theradiussecret
port=1812

Make sure to save your configuration file when done.

Start the Proxy

net start DuoAuthProxy

net stop DuoAuthProxy & net start DuoAuthProxy

# /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.

Configure Amazon WorkSpaces MFA to use Duo

Add the Duo RADIUS server

Ensure that your WorkSpaces directory controllers are able to access your Authentication Proxy server on UDP port 1812 (or whichever port used in the Authentication Proxy configuration). You may need to add custom incoming and outgoing UDP/1812 rules to your VPC Security Groups to allow access. You can either use the security groups from the directory controllers as the source (as shown here), or use the IP addresses defined for the directory in the WorkSpaces console.

1. Log in to the AWS Console and navigate to WorkSpaces > Directories.
2. Select the directory where you want to enable multifactor authentication and click Actions > Update Details
3. On the "Update Directory Details page expand Multi-Factor Authentication.

4. Check the Enable Multi-Factor Authentication option and enter the following information:

   Property	Value
   RADIUS server IP address(es)	Enter the IP address(es) of each Duo Authentication Proxy server (comma-separated).
   Port	Enter 1812 (or whichever port configured on your Duo Authentication Proxy).
   Shared secret code	Enter the RADIUS secret shared with your Duo Authentication Proxy.
   Protocol	Choose PAP.
   Server timeout (in seconds)	Increase the timeout to 20 seconds.
   Max retries	Leave at the default setting.

   

5. Click Update and Exit to save the RADIUS server profile. The RADIUS status for the directory will change to Completed.

High Availability Scenario

You can deploy two or more Duo Authentication Proxy servers for use with WorkSpaces MFA to provide a highly-available MFA solution. For example, you can install the Duo proxy service on two instances in different Availability Zones (AZ) and then configure WorkSpaces MFA RADIUS settings to use both of those proxy machines. That way if the first server does not respond WorkSpaces MFA will send the authentication request to the next listed RADIUS IP address.

Repeat the Authentication Proxy installation steps on a second Linux or Windows machine instance. The proxy configuration should be identical to the first one (including the RADIUS secret). Start the Duo Authentication Proxy on the second machine.

In the WorkSpaces Directory MFA configuration, enter the RADIUS server information as shown in the previous section but enter the IP addresses of all your Authentication Proxy machines as a comma-separated list in the "RADIUS server IP address(es)" field.

Test Your Setup

Launch the WorkSpaces client and enter your primary authentication credentials.

You'll be prompted for additional credentials.

Enter a passcode generated by the Duo Mobile app or a hardware token, or type in the name of an out-of-band factor. You may choose from the following factor names:

You can also specify a number after the factor name if you have more than one device enrolled. So you can enter phone2 or push2 if you have two phones enrolled.

Troubleshooting

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

Network Diagram

1. Client connection initiated to Amazon WorkSpaces
2. Primary authentication using AWS directory
3. AWS directory sends secondary authentication request to Duo Security’s Authentication Proxy
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. Duo Authentication Proxy sends access granted response to AWS directory
8. AWS directory authentication completed
9. Amazon WorkSpaces access granted

Known Issues

• The WorkSpaces client requires input of the secondary factor. Automatic push authentication is not possible at this time.