Duo integrates with your Microsoft Routing and Remote Access Server (RRAS) to add two-factor authentication to VPN Connections.
To integrate Duo with your Microsoft RRAS server, you will need to install a local proxy service on a machine within your network. This Duo proxy server also acts as a RADIUS server — there's usually no need to deploy a separate additional RADIUS server to use Duo.
Once configured, Duo sends your users an automatic authentication request via Duo Push notification to a mobile device or phone call after successful primary login.
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.
This integration communicates with Duo's service on TCP port 443. Also, we do not recommend locking down your firewall to individual IP addresses, since these may change over time to maintain our service's high availability.
You should already have a working primary authentication configuration for your Microsoft RRAS server users before you begin to deploy Duo.
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 7 or later, CentOS 7 or later, or Debian 7 or later).
Then you'll need to:
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!
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).
Ensure that Perl, Python 2.6 or 2.7 (including development headers and libraries), 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 python-devel libffi-devel perl zlib-devel
On Debian-derived systems, install these dependencies by running (as root):
$ apt-get install build-essential python-dev libffi-dev perl zlib1g-dev
Download the most recent Authentication Proxy for Unix from https://dl.duosecurity.com/duoauthproxy-latest-src.tgz. Depending on your download method, the actual filename may reflect the version e.g. duoauthproxy-2.12.0-src.tgz. View checksums for Duo downloads here.
Extract the Authentication Proxy files and build it as follows:
$ tar xzf duoauthproxy-latest-src.tgz $ cd duoauthproxy-version-src $ make
Install the authentication proxy (as root):
$ cd duoauthproxy-build $ ./install
Follow the prompts to complete the installation.
If you ever need to uninstall the proxy, run
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|
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.
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.
To use Active Directory 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 member account that has permission to bind to your Active Directory and perform searches. We recommend creating a service account that has read-only access.|
The password corresponding to
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
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. Other users will not pass primary authentication. For example:
[ad_client] host=22.214.171.124 host_2=126.96.36.199 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.
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
||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. By default, the proxy will attempt to contact your RADIUS server on port 1812. Use
||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"|
[radius_client] host=188.8.131.52 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.
Next, we'll set up the Authentication Proxy to work with your Microsoft RRAS. Create a
[radius_server_auto] section with the following properties:
||Your integration key.|
||Your secret key.|
||Your API hostname (e.g. "api-XXXXXXXX.duosecurity.com").|
||The IP address of your Microsoft RRAS.|
||A secret to be shared between the proxy and your Microsoft RRAS. 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.
This parameter is optional if you only have one "client" section. If you have multiple, each "server" section should specify which "client" to use.
||The port on which to listen for incoming RADIUS Access Requests. Default: 1812.|
Either "safe" or "secure":
The IP address of your second Microsoft RRAS, if you have one. You can specify additional devices as as
The secrets shared with your second Microsoft RRAS, if using one. You can specify secrets for additional devices as
A completed config file that uses Active Directory should look something like:
[ad_client] host=184.108.40.206 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=220.127.116.11 radius_secret_1=radiussecret1 client=ad_client port=1812 failmode=safe
Make sure to save your configuration file when done.
Open an Administrator command prompt and run:
net start DuoAuthProxy
Alternatvely, 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.
On the RRAS server properties Security tab, change the Authentication provider in the drop-down from Windows Authentication to RADIUS Authentication. Then, click the Configure button next to the drop-down to add a new RADIUS server.
In the RADIUS Authentication window, click the Add... button.
Type in the IP or host name of your Duo AuthProxy as the Server name, increase the timeout to 60, and enter 1812 as the port (or the actual port configured for this application on the AuthProxy if not using the 1812 default). Click the Change... button to enter the same shared secret configured on the AuthProxy and click OK.
Ensure the new RADIUS server is listed and click OK again.
Before exiting the RRAS server properties Security tab, click the Authentication Methods... button, and ensure PAP is selected. Click OK.
Click OK on the RRAS server properties Security tab. The RRAS services may require a restart to make the settings effective.
Note: Duo Security supports the use of PAP Authentication with PPTP, SSTP, and L2TP VPN. A Windows PPTP client will not negotiate MPPE (encryption) when PAP is used, meaning the password is sent from the client to the RRAS server as plain text. Duo recommends SSTP or L2TP, which encrypt communication between the client and the RRAS server.
Example for a Windows 7 VPN client, open the VPN connection properties and click the Security tab. Ensure that one of the supported VPN types is selected and that the PAP protocol is selected as well.
Initiate a VPN client connection to verify your configuration.
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 can add a comma (",") to the end of your password, followed by a Duo passcode.
For example, given a username 'bob', with password 'password123' and a Duo passcode '123456', you would enter:
username: bob password: password123,123456
In addition, you may also enter the name of an out-of-band factor in lieu of a passcode. You may choose from the following factor names:
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|
Send a new batch of SMS passcodes
Your authentication attempt will be denied. You can then authenticate with one of the newly-delivered passcodes.
Returning to the previous example, if you wanted to use Duo Push (rather than a passcode) to authenticate, you would enter:
username: bob password: password123,push
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.