If you are using the Barracuda VPN Client then see the Alternate VPN Client Instructions to configure the Barracuda device to use Duo Security's automatic push authentication.
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 Barracuda SSL VPN users before you begin to deploy Duo.
To integrate Duo with your Barracuda SSL VPN, 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 RADIUS server to use Duo.
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 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 OpenSSL, 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 openssl-devel python-devel libffi-devel
On Debian-derived systems, install these dependencies by running (as root):
$ apt-get install build-essential libssl-dev python-dev libffi-dev
To ensure that your Python version will work with the Authentication Proxy, run:
$ python --version
If the output does not say "Python 2.6.x" or "Python 2.7.x", first take note that many distributions can support multiple versions of python simultaneously. If your python installation does not appear to be a supported version, try replacing "python" in the above command with "python2.6" or "python2.7". If neither of these work, then you will need to install a different version of Python. You may need to search additional repositories for your distribution (e.g. for Centos or Red Hat Enterprise Linux, Extra Packages for Enterprise Linux), or build Python from source.
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-2.9.0-src.tgz.
Extract the Authentication Proxy files and build it as follows:
Where python_command is the command to run a Python 2.6 or Python 2.7 interpreter (e.g. "python", "python2.6", "python2.7").
$ tar xzf duoauthproxy-latest-src.tgz $ cd duoauthproxy-version-src $ export PYTHON=python_command $ 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=188.8.131.52 host_2=184.108.40.206 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=220.127.116.11 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 Barracuda SSL VPN. Create a
[radius_server_iframe] 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 Barracuda SSL VPN.|
||A secret to be shared between the proxy and your Barracuda SSL VPN. 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 Barracuda SSL VPN, if you have one. You can specify additional devices as as
The secrets shared with your second Barracuda SSL VPN, if using one. You can specify secrets for additional devices as
A completed config file, using Active Directory as the primary authenticator, should look something like:
[ad_client] host=18.104.22.168 service_account_username=duoservice service_account_password=password1 search_dn=cn=Users,dc=example,dc=com [radius_server_iframe] type=barracuda ikey=DIXXXXXXXXXXXXXXXXXX skey=XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX api_host=api-XXXXXXXX.duosecurity.com radius_ip_1=22.214.171.124 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.
Add a new authentication scheme with the following information:
|Selected modules||Add the "RADIUS" module from the "Available modules" box|
|Selected policies||Add the desired policies from the "Available policies" box|
In the RADIUS section, modify the following settings:
|RADIUS server||The IP address of your Duo Authentication Proxy|
|Shared secret||The RADIUS secret shared with your Duo Authentication Proxy|
|Password prompt text||Password|
To test your setup, go to the URL you normally use to log in to your Barracuda SSL VPN. After you complete the primary authentication, Duo enrollment/login should appear.