Two factor authentication for Remote Desktop Gateway (RD Gateway) with RADIUS

 

The LoginTC RD Gateway with RADIUS Connector protects access to your Microsoft Remote Desktop Gateway (RD Gateway) by adding a second factor LoginTC challenge to existing username and password authentication to your Remote Desktop resources.

This guide instructs you on how to configure your RD Gateway to use the LoginTC RADIUS Connector for two-factor authentication. If you would like to protect your RD Web Access then you may be interested in the: LoginTC RD Web Access Connector.

Video Instructions Architecture

Authentication Flow

1. A user attempts access with their Remote Desktop client with username / password
2. The username / password is verified against an existing first factor directory (i.e. Active Directory)
3. A RADIUS authentication request is sent to the LoginTC RADIUS Connector
4. An authentication request is made to LoginTC Cloud Services
5. Secure push notification request sent to the user’s mobile or desktop device
6. User response (approval or denial of request) sent to LoginTC Cloud Services
7. The LoginTC RADIUS Connector polls until the user responds or a timeout is reached
8. RADIUS Access-Accept sent back to Remote Desktop Gateway
9. User is granted access to Remote Desktop

Prerequisites

Before proceeding, please ensure you have the following:

• LoginTC Admin Panel account
• Microsoft Windows Server 2012 R2 running the RD Gateway role
• Computer virtualization software such as VMware ESXi, VirtualBox, or Hyper-V
• Virtual Machine requirements:
  • 1024 MiB RAM
  • 8 GiB disk size

Create Application

Start by creating a LoginTC Application for your deployment. An Application represents a service (e.g. An application is a service (e.g., VPN or web application) that you want to protect. e) that you want to protect with LoginTC.

Create a LoginTC Application in LoginTC Admin Panel, follow Create Application Steps.

If you have already created a LoginTC Application for your deployment, then you may skip this section and proceed to Installation.

Installation

1. Download the latest LoginTC RADIUS Connector:
   • OVF for ESXi, VirtualBox
   • VHD for Hyper-V
2. Unzip the file
3. Import the virtual appliance your computer virtualization software
   • Instructions for Hyper-V
4. Ensure that the LoginTC RADIUS Connector has a virtual network card
5. Start the virtual appliance
6. You will be presented with a console dashboard:
7. The first thing you must do is set the logintc-user password:
8. By default the appliance network is configured by DHCP. If you wish to manually configure the network, use the Down arrow key to navigate to Network Configuration and DNS Configuration
9. For access to the web interface select Web Server and then Start:It may take 5-10 seconds to start the first time:
10. Once started, access the web interface by navigating to the URL mentioned in the information box:

The LoginTC RADIUS Connector runs CentOS 7.7 with SELinux. A firewall runs with the following open ports:

Port	Protocol	Purpose
22	TCP	SSH access
1812	UDP	RADIUS authentication
1813	UDP	RADIUS accounting
8888	TCP	Web interface
443	TCP	Web interface
80	TCP	Web interface
80	TCP	Package updates (outgoing)
123	UDP	NTP, Clock synchronization (outgoing)

Configuration for Remote Desktop Gateway 2FA

Configuration describes how the appliance will authenticate your RADIUS-speaking device with an optional first factor and LoginTC as a second factor. Each configuration has 4 Sections:

1. LoginTC

This section describes how the appliance itself authenticates against LoginTC Admin Panel with your LoginTC Application. Only users that are part of your organization and added to the domain configured will be able to authenticate.

2. First Factor

This section describes how the appliance will conduct an optional first factor. Either against an existing LDAP, Active Directory or RADIUS server. If no first factor is selected, then only LoginTC will be used for authentication.

3. Passthrough

This section describes whether the appliance will perform a LoginTC challenge for an authenticating user. The default is to challenge all users. However with either a static list or Active Directory / LDAP Group you can control whom gets challenged to facilitate seamless testing and rollout.

4. Client and Encryption

This section describes which RADIUS-speaking device (i.e., your RD Gateway) will be connecting to the appliance and whether to encrypt API Key, password and secret parameters.

The web interface makes setting up a configuration simple and straightforward. Each section has a Test feature, which validates each input value and reports all potential errors. Section specific validation simplifies troubleshooting and gets your infrastructure protected correctly faster.

First Configuration

Close the console and navigate to your appliance web interface URL. Use username logintc-user and the password you set upon initial launch of the appliance. You will now configure the LoginTC RADIUS Connector.

Create a new configuration file by clicking + Create your first configuration:

LoginTC Settings

Configure which LoginTC Application to us:

Configuration values:

Property	Explanation
Application ID	The 40-character Application ID, retrieve Application ID
Application API Key	The 64-character Application API Key, retrieve Application API Key
Request Timeout	Number of seconds that the RADIUS connector will wait for

The Application ID and Application API Key are found on the LoginTC Admin Panel.

Click Test to validate the values and then click Next:

First Authentication Factor

The LoginTC RADIUS Connector will not be performing the first factor authentication. Choose the None option and continue.

Passthrough

Configure which users will be challenged with LoginTC. This allows you to control how LoginTC will be phased in for your users. This flexibility allows for seamless testing and roll out.

For example, with smaller or proof of concept deployments select the Static List option. Users on the static list will be challenged with LoginTC, while those not on the list will only be challenged with the configured First Authentication Factor. That means you will be able to test LoginTC without affecting existing users accessing your VPN.

For larger deployments you can elect to use the Active Directory or LDAP Group option. Only users part of a particular LDAP or Active Directory Group will be challenged with LoginTC. As your users are migrating to LoginTC your LDAP and Active Directory group policy will ensure that they will be challenged with LoginTC. Users not part of the group will only be challenged with the configured First Authentication Factor.

No Passthrough (default)

Select this option if you wish every user to be challenged with LoginTC.

Static List

Select this option if you wish to have a static list of users that will be challenged with LoginTC. Good for small number of users.

LoginTC challenge users: a new line separated list of usernames. For example:

            jane.doe
            jane.smith
            john.doe
            john.smith

Active Directory / LDAP Group

Select this option if you wish to have only users part of a particular Active Directory or LDAP group to be challenged with LoginTC. Good for medium and large number of users.

Configuration values:

Property	Explanation	Examples
LoginTC challenge auth groups	Comma separated list of groups for which users will be challenged with LoginTC	SSLVPN-Users or two-factor-users
host	Host or IP address of the LDAP server	ldap.example.com or 192.168.1.42
port (optional)	Port if LDAP server uses non-standard (i.e., 389/636)	4000
bind_dn	DN of a user with read access to the directory	cn=admin,dc=example,dc=com
bind_password	The password for the above bind_dn account	password
base_dn	The top-level DN that you wish to query from	dc=example,dc=com
attr_username	The attribute containing the user’s username	sAMAccountName or uid
attr_name	The attribute containing the user’s real name	displayName or cn
attr_email	The attribute containing the user’s email address	mail or email
encryption (optional)	Encryption mechanism	ssl or startTLS
cacert (optional)	CA certificate file (PEM format)	/opt/logintc/cacert.pem

Click Test to validate the values and then click Next.

Client and Encryption

Configure RADIUS client (e.g. your RD Gateway):

Client configuration values:

Property	Explanation	Examples
name	A unique identifier of your RADIUS client	CorporateGateway
ip	The IP address of your RADIUS client (e.g. your RD Gateway)	192.168.1.44
secret	The secret shared between the LoginTC RADIUS Connector and its client	bigsecret

Under Authentication Mode select Direct

The LoginTC RADIUS Connector will directly and automatically perform the LoginTC second factor.

Click Test to validate the values and then click Save.

Testing

When you are ready to test your configuration, create a LoginTC user (if you haven’t already done so). The username should match your existing user. Provision a token by following the steps:

1. In a new tab / window log into the LoginTC Admin Panel
2. Click Domains
3. Click on your domain
4. Click on Members
5. Click Issue Token button beside your user:
6. A 10-character alphanumeric activation code will appear beside the user:
7. Open the LoginTC mobile app.
8. Enter the 10-character alphanumeric activation code:
9. Load the token to complete the process

When you have loaded a token for your new user and domain, navigate to your appliance web interface URL:

Click Test Configuration:

Enter a valid username and password; if there is no password leave it blank. A simulated authentication request will be sent to the mobile or desktop device with the user token loaded. Approve the request to continue:

Congratulations! Your appliance can successfully broker first and second factor authentication. The only remaining step is to configure your RADIUS device!

If there was an error during testing, the following will appear:

In this case, click See logs and then click the /var/log/logintc/authenticate.log tab to view the log file and troubleshoot:

RD Gateway Configuration

Once you have configured the LoginTC RADIUS Connector you will be able to configure your RD Gateway to use the LoginTC RADIUS Connector for second-factor authentication.

1. Open the RD Gateway Manager from your Start Menu
2. Right click on your RD server in the left sidebar and click on Properties
3. Select the RD CAP Store tab
4. Select Central server running NPS radio button
5. Enter the IP address of your LoginTC RADIUS Connector and press Add button
6. Enter the shared secret that you configured on the LoginTC RADIUS Connector and press OK
7. Press the Apply button
8. Press the OK button
9. Open the Network Policy Server manager
10. Expand RADIUS Clients and Servers in the left sidebar
11. Select Remote RADIUS Server
12. Right click on TS GATEWAY SERVER GROUP and click on Properties
13. Select your RADIUS server and press Edit…
14. Select the Load Balancing tab
15. Set the timeout settings to 120 seconds
16. Press the Apply button
17. Press the OK button to close the dialog
18. Expand Policies in the left sidebar
19. Click on Connection Request Policies
20. Right click on TS GATEWAY AUTHORIZATION POLICY and click on Properties
21. Click on Settings tab
22. Select Authentication and ensure that it’s set to Forward requests to the remote RADIUS server
23. Click on Policies –> Network Policies
24. Double click on your RDG CAP policy
25. Click on the Conditions tab
26. Select the Called Station ID attribute and press the Edit… button
27. Set the value to UserAuthType:(PW|CA)
28. Press the OK button
29. Press the Apply button

You may now test your RD Gateway.

User Management

Create users in LoginTC corresponding to your AD/LDAP users and provision them tokens. There are several options for managing your users within LoginTC:

• Individual users can be added manually in LoginTC Admin Panel
• Bulk operations using CSV Import
• Programmatically manage user lifecycle with the REST API
• One way user synchronization to LoginTC Admin is performed using User Sync Tool.

For more details about user management and provisioning, visit the User Management guide.

Logging

Logs can be found on the Logs tab:

Troubleshooting

Not Authenticating

If you are unable to authenticate, navigate to your LoginTC RADIUS Connector appliance web interface URL and click Status:

Ensure that all the status checks pass. For additional troubleshooting, click Logs:

You may also find valuable information in the Microsoft Event Viewer under Custom Views → ServerRoles → Network Policy and Access Services

Upgrading

From 3.X

Follow these instructions to upgrade your LoginTC RADIUS virtual appliance to the latest version (3.0.7):

1. SSH into the virtual appliance or open the console (use same username / password as web GUI)
2. cd /tmp
3. curl -O https://www.logintc.com/downloads/logintc-radius-connector-3.0.7-upgrade.sh
4. sudo sh logintc-radius-connector-3.0.7-upgrade.sh

The upgrade script will restart your appliance after upgrading.

From 2.X

Complete 2.X to 3.X upgrade guide: LoginTC RADIUS Connector Upgrade Guide

Related Connectors

You may also be interested in our:

• Remote Desktop (RDP) and Local Logon 2FA Connector
• Remote Desktop Web Access (RD Web) 2FA Connector
• Office 365 2FA Connector
• Outlook Web App (OWA) 2FA Connector
• Windows Server 2012 2FA Connector
• Windows Server 2016 and 2019 2FA Connector