Prerequisites for the Microsoft Tunnel in Intune

Before you can install the Microsoft Tunnel VPN gateway for Microsoft Intune, review and configure prerequisites. Prerequisites include use of a Linux server that runs containers to host the Tunnel server software. Also plan to configure your network, firewalls, and proxies to support communications for the Microsoft Tunnel.

At a high level, the Microsoft Tunnel requires:

• An Azure subscription.

• A Microsoft Intune Plan 1 subscription.

  Note

  This prerequisite is for Microsoft Tunnel, and does not include Microsoft Tunnel for Mobile Application Management, which is an Intune add-on that requires a Microsoft Intune Plan 2 subscription.

• A Linux server that runs containers. The server can be on-premises or in the cloud, and supports one of the following container types:

  • Podman for Red Hat Enterprise Linux (RHEL). See the Linux server requirements.
  • Docker for all other Linux distributions.

• A Transport Layer Security (TLS) certificate for the Linux server to secure connections from devices to the Tunnel Gateway server.

• Devices that run Android or iOS/iPadOS.

After configuring the prerequisites, we recommend you run the readiness tool to help validate that your environment is well configured for a successful installation.

The following sections detail the prerequisites for the Microsoft Tunnel, and provide guidance on using the readiness tool.

Linux server

Set up a Linux based virtual machine or a physical server on which to install the Microsoft Tunnel Gateway.

• Supported Linux distributions - The following table details which versions of Linux are supported for the Tunnel server, and the container they require:

  Distribution version	Container requirements	Considerations
  CentOS 7.4+	Docker CE	Support ends June 2024. CentOS 8+ isn't supported
  Red Hat (RHEL) 7.4+	Docker CE	Support ends June 2024
  Red Hat (RHEL) 8.6	Support ends June 2024 Podman 4.0 (default) Podman 3.0	This version of RHEL doesn't automatically load the ip_tables module into the Linux kernel. When you use this version, plan to manually load the ip_tables before Tunnel is installed. Containers created by Podman v3 and earlier aren't usable with Podman v4.0. If upgrading and changing containers from v3 to v4.0, plan to create new containers and to uninstall and then reinstall Microsoft Tunnel.
  Red Hat (RHEL) 8.7	Podman 4.2 (default)	This version of RHEL doesn't automatically load the ip_tables module into the Linux kernel. When you use this version, plan to manually load the ip_tables before Tunnel is installed. Containers created by Podman v3 and earlier aren't usable with Podman v4.2 and later. If upgrading and changing containers, plan to create new containers and to uninstall and then reinstall Microsoft Tunnel.
  Red Hat (RHEL) 8.8	Podman 4.4.1	This version of RHEL doesn't automatically load the ip_tables module into the Linux kernel. When you use this version, plan to manually load the ip_tables before Tunnel is installed. Containers created by Podman v3 and earlier aren't usable with Podman v4.2 and later. If upgrading and changing containers, plan to create new containers and to uninstall and then reinstall Microsoft Tunnel.
  Red Hat (RHEL) 8.9	Podman 4.4.1	This version of RHEL doesn't automatically load the ip_tables module into the Linux kernel. When you use this version, plan to manually load the ip_tables before Tunnel is installed. Containers created by Podman v3 and earlier aren't usable with Podman v4.2 and later. If upgrading and changing containers, plan to create new containers and to uninstall and then reinstall Microsoft Tunnel.
  Red Hat (RHEL) 8.10	Podman 4.9.4-rhel (default)	This version of RHEL doesn't automatically load the ip_tables module into the Linux kernel. When you use this version, plan to manually load the ip_tables before Tunnel is installed. Containers created by Podman v3 and earlier aren't usable with Podman v4.2 and later. If upgrading and changing containers, plan to create new containers and to uninstall and then reinstall Microsoft Tunnel.
  Red Hat (RHEL) 9.0	Support ends June 2024 Podman 4.4.1 (default)	This version of RHEL doesn't automatically load the ip_tables module into the Linux kernel. When you use this version, plan to manually load the ip_tables before Tunnel is installed. Containers created by Podman v3 and earlier aren't usable with Podman v4.2 and later. If upgrading and changing containers, plan to create new containers and to uninstall and then reinstall Microsoft Tunnel. Support ends Feb 2024.
  Red Hat (RHEL) 9.1	Podman 4.4.1 (default)	This version of RHEL doesn't automatically load the ip_tables module into the Linux kernel. When you use this version, plan to manually load the ip_tables before Tunnel is installed. Containers created by Podman v3 and earlier aren't usable with Podman v4.2 and later. If upgrading and changing containers, plan to create new containers and to uninstall and then reinstall Microsoft Tunnel.
  Red Hat (RHEL) 9.2	Podman 4.4.1 (default)	This version of RHEL doesn't automatically load the ip_tables module into the Linux kernel. When you use this version, plan to manually load the ip_tables before Tunnel is installed. Containers created by Podman v3 and earlier aren't usable with Podman v4.2 and later. If upgrading and changing containers, plan to create new containers and to uninstall and then reinstall Microsoft Tunnel.
  Red Hat (RHEL) 9.3	Podman 4.6.1. (default)	This version of RHEL doesn't automatically load the ip_tables module into the Linux kernel. When you use this version, plan to manually load the ip_tables before Tunnel is installed. Containers created by Podman v3 and earlier aren't usable with Podman v4.2 and later. If upgrading and changing containers, plan to create new containers and to uninstall and then reinstall Microsoft Tunnel.
  Red Hat (RHEL) 9.4	Podman 4.9.4-rhel (default)	This version of RHEL doesn't automatically load the ip_tables module into the Linux kernel. When you use this version, plan to manually load the ip_tables before Tunnel is installed. Containers created by Podman v3 and earlier aren't usable with Podman v4.2 and later. If upgrading and changing containers, plan to create new containers and to uninstall and then reinstall Microsoft Tunnel.
  Ubuntu 20.04	Docker CE
  Ubuntu 22.04	Docker CE

  Important

  In April of 2023, Ubuntu will end support for Ubuntu 18.04. With the end of support by Ubuntu, Intune will also end support for Ubuntu 18.04 for use with Microsoft Tunnel. For more information, see https://wiki.ubuntu.com/Releases.

• Size the Linux server: Use the following guidance to meet your expected use:

  # Devices	# CPUs	Memory GB	# Servers	# Sites	Disk Space GB
  1,000	4	4	1	1	30
  2,000	4	4	1	1	30
  5,000	8	8	2	1	30
  10,000	8	8	3	1	30
  20,000	8	8	4	1	30
  40,000	8	8	8	1	30

  Support scales linearly. While each Microsoft Tunnel supports up to 64,000 concurrent connections, individual devices can open multiple connections.

• CPU: 64-bit AMD/Intel processor.

• Install Docker CE or Podman: Depending on the version of Linux you use for your Tunnel server, install one of the following on the server:

  • Docker version 19.03 CE or later.
  • Podman version 3.0 or 4.0 depending on the version of RHEL.

  Microsoft Tunnel requires Docker or Podman on the Linux server to provide support for containers. Containers provide a consistent execution environment, health monitoring and proactive remediation, and a clean upgrade experience.

  For information about installing and configuring Docker or Podman, see:

  • Install Docker Engine on CentOS or Red Hat Enterprise Linux 7.

    Note

    The preceding link directs you to the CentOS download and installation instructions. Use those same instructions for RHEL 7.4. The version installed on RHEL 7.4 by default is too old to support Microsoft Tunnel Gateway.

  • Install Docker Engine on Ubuntu.

  • Install Podman on Red Hat Enterprise Linux 8.4 and later (scroll down to RHEL8).

    These versions of RHEL don't support Docker. Instead, these versions use Podman, and podman is part of a module called "container-tools". In this context, a module is a set of RPM packages that represent a component and that usually install together. A typical module contains packages with an application, packages with the application-specific dependency libraries, packages with documentation for the application, and packages with helper utilities. For more information, see Introduction to modules in the Red Hat documentation.

    Note

    Rootless Podman: Microsoft Tunnel supports use of a rootless Podman container.

    Use of rootless Podman requires additional prerequisites to those detailed in this article, and the use of a modified command line when you start the Tunnel installation script. For information about the additional prerequisites and installation command line, see Use a rootless Podman container in the Configure Microsoft Tunnel for Intune article.

• Transport Layer Security (TLS) certificate: The Linux server requires a trusted TLS certificate to secure the connection between devices and the Tunnel Gateway server. During installation of the Tunnel Gateway, you add to the server the TLS certificate and full trusted certificate chain.

  • The Subject Alternative Name (SAN) of the TLS certificate you use to secure the Tunnel Gateway endpoint must match the IP address or FQDN of the Tunnel Gateway server.

  • TLS certificate can't have an expiration date longer than two years. If the date is longer than two years, it isn't accepted on iOS devices.

  • Support of wildcards is limited. For example, *.contoso.com is supported, but cont*.com isn't supported.

  • During installation of the Tunnel Gateway server, you must copy the entire trusted certificate chain to your Linux server. The installation script provides the location where you copy the certificate files and prompts you to do so.

  • If you use a TLS certificate that isn't publicly trusted, you must push the entire trust chain to devices using an Intune Trusted certificate profile.

  • The TLS certificate can be in PEM or pfx format.

  • To support the TLS certificate revocation health check, ensure the Online Certificate Status Protocol (OCSP) or certificate revocation list (CRL) address as defined by the TLS certificate is accessible from the server.

  • Configure the Tunnel clients certificate with a key that is 2048-bits or larger. We recommend larger keys to help your deployment stay in support for future and evolving SSL/TLS requirements by various SSL/TLS library solutions.

    Tip

    Periodically review the requirements of your chosen SSL/TLS library to ensure your infrastructure and certificates remain supported and in compliance to recent changes for that library, and reissue Tunnel client certificates when necessary to stay current with your solutions evolving requirements.

• TLS version: By default, connections between Microsoft Tunnel clients and servers use TLS 1.3. When TLS 1.3 isn't available, the connection can fall back to use TLS 1.2.

Default bridge network

Both Podman and Docker containers use a bridge network to forward traffic through the Linux host. When the containers bridge network conflicts with a corporate network, Tunnel Gateway can't successfully route traffic to that corporate network.

The default bridge networks are:

• Docker: 172.17.0.0/16
• Podman: 10.88.0.0/16

To avoid conflicts, you can reconfigure both Podman and Docker to use a bridge network that you specify.

Change the default bridge network used by Docker

Docker uses the file /etc/docker/daemon.json to configure a new default bridge IP address. In the file, the bridge IP address must be specified in CIDR (Classless inter-domain routing) notation, a compact way to represent an IP address along with its associated subnet mask and routing prefix.

1. Use the following command to stop the MS Tunnel Gateway container: sudo mst-cli server stop ; sudo mst-cli agent stop

2. Next, run the following command to remove the existing Docker bridge device: sudo ip link del docker0

3. If the file /etc/docker/daemon.json is present on your server, use a file editor like vi or nano to modify the file. Run the file editor with root or sudo permissions:

   • When the "bip": entry is present with an IP address, modify it by adding a new IP address in CIDR notation.
   • When the "bip": entry isn't present, you must add both the value "bip": and the new IP address in CIDR notation.

   The following example shows the structure of a daemon.json file with an updated "bip": entry that uses a modified IP address of "192.168.128.1/24".

   Example of daemon.json:

   {
   "bip": "192.168.128.1/24"
   }
   

4. If the file /etc/docker/daemon.json isn't present on your server, run a command similar to the following example to create the file and define the bridge IP that you want to use.

   Example: sudo echo '{ "bip":"192.168.128.1/24" }' > /etc/docker/daemon.json

5. Use the following command to start the MS Tunnel Gateway container: sudo mst-cli agent start ; sudo mst-cli server start

For more information, see Use bridge networks in the Docker documentation.

Change the default bridge network used by Podman

Podman uses the file /etc/cni/net.d as 87-podman-bridge.conflist to configure a new default bridge IP address.

1. Use the following command to stop the MS Tunnel Gateway container: sudo mst-cli server stop ; sudo mst-cli agent stop

2. Next, run the following command to remove the existing Podman bridge device: sudo ip link del cni-podman0

3. Using root permissions and a file editor like vi or nano, modify /etc/cni/net.d as 87-podman-bridge.conflist to update the defaults for "subnet:" and "gateway:" by replacing the Podman default values with your desired subnet and gateway addresses. The subnet address must be specified in CIDR notation.

   The Podman defaults are:

   • subnet: 10.88.0.0/16
   • gateway: 10.88.0.1

4. Use the following command to restart the MS Tunnel Gateway containers: sudo mst-cli agent start ; sudo mst-cli server start

For more information, see Configuring container networking with Podman in the Red Hat documentation.

Linux system auditing

Linux system auditing can help identify security-relevant information or security violations on a Linux server that hosts Microsoft Tunnel. Linux system auditing is recommended for Microsoft Tunnel, but not required. To use system auditing, a Linux server must have the auditd package installed to /etc/audit/auditd.conf.

Details on how to implement auditing depend on the Linux platform you use:

• Red Hat: Versions of Red Had Enterprise Linux 7 and later install the auditd package by default. However, if the package isn't installed, you can use the following command line on the Linux server to install it: sudo dnf install audit audispd-plugins

  Typically, the auditd package is available from the default repository of each REHL version.

  For more information about using system auditing on RHEL, see Configure Linux system auditing with auditd in the Red Hat Blog.

• Ubuntu: To use system auditing with Ubuntu you must manually install the auditd package. To do so, use the following command line on the Linux server: sudo apt install auditd audispd-plugins

  Typically, the auditd package is available from the default repository of each Ubuntu version.

  For more information about using system auditing on Ubuntu, see How to setup and Install Auditd on Ubuntu, an article that is available on the dev.to website that was originally published at kubefront.com.

Network

• Enable packet forwarding for IPv4: Each Linux server that hosts the Tunnel server software must have IP forwarding for IPv4 enabled. To check on the status of IP forwarding, on the server run one of the following generic commands as root or sudo. Both commands return a value of 0 for disabled and a value of 1 for enabled:

  • sysctl net.ipv4.ip_forward
  • cat /proc/sys/net/ipv4/ip_forward

  If not enabled, you can temporarily enable IP forwarding by running one of the following generic commands as root or sudo on the server. These commands can change the IP forwarding configuration until the server restarts. After a restart, the server returns IP forwarding behavior to its previous state. For both commands, use a value of 1 to enable forwarding. A value of 0 disables forwarding. The following command examples use a value of 1 to enable forwarding:

  • sysctl -w net.ipv4.ip_forward=1
  • echo 1 > /proc/sys/net/ipv4/ip_forward

  To make IP forwarding permanent, on each Linux server edit the /etc/sysctl.conf file and remove the leading hashtag (#) from #net.ipv4.ip_forward=1 to enable packet forwarding. After your edit, the entry should appear as follows:

  # Uncomment the next line to enable packet forwarding for IPv4
  net.ipv4.ip_forward=1
  

  For this change to take effect, you must either reboot the server or run sysctl -p.

  If the expected entry isn't present in the sysctl.conf file, consult the documentation for the distribution you use for how to enable IP forwarding. Typically, you can edit sysctl.conf to add the missing line at the end of the file to permanently enable IP forwarding.

• Configure multiple NICs per server (Optional): We recommend using two Network Interface controllers (NICs) per Linux server to improve performance, though use of two is optional.

  • NIC 1 - This NIC handles traffic from your managed devices and should be on a public network with public IP address.  This IP address is the address that you configure in the Site configuration. This address can represent a single server or a load balancer.

  • NIC 2 - This NIC handles traffic to your on-premises resources and should be on your private internal network without network segmentation.

• Ensure cloud-based Linux VMs can access your on-premises network: If you run Linux as a VM in a cloud, ensure the server can access your on-premises network. For example, for a VM in Azure, you can use Azure ExpressRoute or something similar to provide access. Azure ExpressRoute isn't necessary when you run the server in a VM on-premises.

• Load balancers (Optional): If you choose to add a load balancer, consult your vendors documentation for configuration details. Take into consideration network traffic and firewall ports specific to Intune and the Microsoft Tunnel.

  The Tunnel server responds to GET requests with a static page. The response is used as a probe by load balancers as a way to check for the liveness of Tunnel server. The response is static and doesn't contain sensitive information.

• Per-app VPN and Top-level domain support - Per-app-VPN use with internal use of local top-level domains isn't supported by Microsoft Tunnel.

Firewall

By default, the Microsoft Tunnel and server use the following ports:

Inbound ports:

• TCP 443 – Required by Microsoft Tunnel.
• UDP 443 – Required by Microsoft Tunnel.
• TCP 22 – Optional. Used for SSH/SCP to the Linux server.

Outbound ports:

• TCP 443 – Required to access Intune services. Required by Docker or Podman to pull images.

When creating the Server configuration for the tunnel, you can specify a different port than the default of 443. If you specify a different port, configure firewalls to support your configuration.

More requirements:

To access the security token service and Azure storage for logs, provide access to the following FQDNs:

• Security Token Service: *.sts.windows.net
• Azure storage for tunnel logs: *.blob.core.windows.net
• Other storage endpoint urls: *.blob.storage.azure.net
• Microsoft Intune: *.manage.microsoft.com
• Microsoft authentication: login.microsoftonline.com
• Microsoft Graph: graph.microsoft.com
• Configure firewall rules to support the configurations detailed in Microsoft Artifact Registry (MAR) Client Firewall Rules Configuration.

Proxy

You can use a proxy server with Microsoft Tunnel.

The following considerations can help you configure the Linux server and your environment for success:

Configure an outbound proxy for Docker

• If you use an internal proxy, you might need to configure the Linux host to use your proxy server by using environment variables. To use the variables, edit the /etc/environment file on the Linux server, and add the following lines:

  http_proxy=[address]
https_proxy=[address]

• Authenticated proxies aren't supported.

• The proxy can't perform break and inspect because the Linux server uses TLS mutual authentication when connecting to Intune.

• Configure Docker to use the proxy to pull images. To do so, edit the /etc/systemd/system/docker.service.d/http-proxy.conf file on the Linux server and add the following lines:

  [Service]
  Environment="HTTP_PROXY=http://your.proxy:8080/"
  Environment="HTTPS_PROXY=https://your.proxy:8080/"
  Environment="NO_PROXY=127.0.0.1,localhost"
  

  Note

  Microsoft Tunnel doesn't support Microsoft Entra application proxy, or similar proxy solutions.

Configure an outbound proxy for Podman

The following details can help you configure an internal proxy when using Podman:

• Authenticated proxies aren't supported.

• The proxy can't perform break and inspect because the Linux server uses TLS mutual authentication when connecting to Intune.

• Podman reads HTTP Proxy information stored in /etc/profile.d/http_proxy.sh. If this file doesn't exist on your server, create it. Edit http_proxy.sh to add the following two lines. In the following lines, 10.10.10.1:3128 is an example address:port entry. When you add these lines, replace 10.10.10.1:3128 with the values for your proxy IP address:port:

  export HTTP_PROXY=http://10.10.10.1:3128
export HTTPS_PROXY=http://10.10.10.1:3128

  If you have access to Red Hat Customer Portal, you can view the knowledge base article associated with this solution. See Setting up HTTP Proxy variables for Podman - Red Hat Customer Portal.

• When you add those two lines to http_proxy.sh before you install Microsoft Tunnel Gateway by running the mstunnel-setup, the script automatically configures the Tunnel Gateway proxy environment variables in /etc/mstunnel/env.sh.

  To configure a proxy after the Microsoft Tunnel Gateway setup is complete, do the following actions:

  1. Modify or create the file /etc/profile.d/http_proxy.sh and add the two lines from the previous bullet point.

  2. Edit /etc/mstunnel/env.sh and add the following two lines to end of the file. Like the previous lines, replace the example address:port value of 10.10.10.1:3128 with the values for your proxy IP address:port:

     HTTP_PROXY=http://10.10.10.1:3128
HTTPS_PROXY=http://10.10.10.1:3128

  3. Restart the Tunnel Gateway server: Run mst-cli server restart

  Be aware that RHEL uses SELinux. Because a proxy that doesn't run on a SELinux port for http_port_t can require extra configuration, check on the use of SELinux managed ports for http. To view the configurations, run the following command: sudo semanage port -l | grep "http_port_t"

  Example of the results of the port check command. In this example, the proxy uses 3128 and isn't listed:

  

  • If your proxy runs on one of the SELinux ports for http_port_t, then you can continue with the Tunnel Gateway install process.

  • If your proxy does't run on a SELinux port for http_port_t as in the preceding example, you must make extra configurations.

    If your proxy port is not listed for http_port_t, check if the proxy port is used by another service. Use the semanage command to first check the port that your proxy uses and then later if needed, to change it. To check the port your proxy uses, run: sudo semanage port -l | grep "your proxy port"

    Example of the results of checking for a service that might use the port:

    

    • In the example, the port we expect (3128) is used by squid, which happens to be an OSS proxy service. Squid proxy SELinux policies are part of many common distributions. Because squid uses port 3128 (our example port), we must modify the http_port_t ports and add port 3128 to be allowed via SELinux for the proxy used by Tunnel. To modify the port use, run the following command: sudo semanage port -m -t http_port_t -p tcp "your proxy port"

      Example of the command to modify the port:

      

      After running the command to change the port, run the following command to check if the port is used by another service: sudo semanage port -l | grep "your proxy port"

      Example of the command to check the port after modifying the port:

      

      In this example, port 3128 is now associated with both http_port-t and squid_port_t. That result is expected. If your proxy port isn't listed when running the sudo semanage port -l | grep "your_proxy_port" command, then run the command to modify the port again, but the -m in the semanage command with -a: sudo semanage port -a -t http_port_t -p tcp "your proxy port"

Configure Podman to use the proxy to download image updates

You can configure Podman to use the proxy to download (pull) updated images for Podman:

1. On the tunnel server, use a command prompt to run the following command to open an editor for the override file for the Microsoft Tunnel service:

   systemctl edit --force mstunnel_monitor

2. Add the following three lines to the file. Replace each instance of [address] with your proxy DN or address, and then save the file:

   [Service]
   Environment="http_proxy=[address]"
   Environment="https_proxy=[address]"
   

3. Next, run the following at the command prompt:

   systemctl restart mstunnel_monitor

4. Finally, run the following at the command prompt to confirm the configuration is successful:

   systemctl show mstunnel_monitor | grep http_proxy

   If configuration is successful, the results resemble the following information:

   Environment="http_proxy=address:port"
   Environment="https_proxy=address:port"
   

Update the proxy server in use by the tunnel server

To change the proxy server configuration that is in use by the Linux host of the tunnel server, use the following procedure:

1. On the tunnel server, edit /etc/mstunnel/env.sh and specify the new proxy server.

2. Run mst-cli install.

   This command rebuilds the containers with the new proxy server details. During this process, you're asked to verify the contents of /etc/mstunnel/env.sh and to make sure that the certificate is installed. The certificate should already be present from the previous proxy server configuration.

   To confirm both and complete the configuration, enter yes.

Platforms

Devices must be enrolled to Intune to be supported with Microsoft Tunnel. Only the following device platforms are supported:

• iOS/iPadOS

• Android Enterprise:

  • Fully Managed
  • Corporate-Owned Work Profile
  • Personally-Owned Work profile

  Note

  Android Enterprise dedicated devices aren't supported by the Microsoft Tunnel.

All platforms support the following functionality:

• Microsoft Entra authentication to the Tunnel using username and password.
• Active Directory Federation Services (AD FS) authentication to the Tunnel using username and password.
• Per-app support.
• Manual full-device tunnel through a Tunnel app, where the user launches VPN and selects Connect.
• Split tunneling. However, on iOS split tunneling rules are ignored when your VPN profile uses per app VPN.

Support for a Proxy is limited to the following platforms:

• Android 10 and later
• iOS/iPadOS

Permissions

To manage the Microsoft Tunnel, users must have permissions that are included in the Microsoft Tunnel Gateway permissions group in Intune. By default, Intune Administrators and Microsoft Entra administrators have these permissions. You can also add them to custom roles you create for your Intune tenant.

While configuring a role, on the Permissions page, expand Microsoft Tunnel Gateway and then select the permissions you want to grant.

The Microsoft Tunnel Gateway permissions group grants the following permissions:

• Create - Configure Microsoft Tunnel Gateway Servers and Sites. Server configurations include settings for IP address ranges, DNS servers, ports, and split tunneling rules. Sites are logical groupings of multiple servers that support Microsoft Tunnel.

• Update (modify) - Update Microsoft Tunnel Gateway server configurations and sites. Server configurations include settings for IP address ranges, DNS servers, ports, and split tunneling rules. Sites are logical groupings of multiple servers that support Microsoft Tunnel.

• Delete - Delete Microsoft Tunnel Gateway server configurations and sites. Server configurations include settings for IP address ranges, DNS servers, ports, and split tunneling rules. Sites are logical groupings of multiple servers that support Microsoft Tunnel.

• Read - View Microsoft Tunnel Gateway server configurations and sites. Server configurations include settings for IP address ranges, DNS servers, ports, and split tunneling rules. Sites are logical groupings of multiple servers that support Microsoft Tunnel.

Run the readiness tool

Before you start a server install, we recommend you download and run the most recent version of the mst-readiness tool. The tool is a script that runs on your Linux server and does the following actions:

• Validates that the Microsoft Entra account you use to install Microsoft Tunnel has the required roles to complete enrollment.

• Confirms that your network configuration allows Microsoft Tunnel to access the required Microsoft endpoints.

• Checks for the presence of the ip_tables module on the Linux server. This check was added to the script on February 11 2022, when support for RHEL 8.5 was added. RHEL 8.5 later don't load the ip_tables module by default. If they're missing after the Linux server installs, you must manually load the ip_tables module.

The mst-readiness tool has a dependency on jq, a command-line JSON processor. Before you run the readiness tool, ensure jq is installed. For information about how to get and install jq, see the documentation for the version of Linux that you use.

To use the readiness tool:

1. Get the most recent version of the readiness tool by using one of the following methods:

   • Download the tool directly by using a web browser. Go to https://aka.ms/microsofttunnelready to download a file named mst-readiness.

   • Sign in to Microsoft Intune admin center > Tenant administration > Microsoft Tunnel Gateway, select the Servers tab, select Create to open the Create a server pane, and then select Download readiness tool.

   • Use a Linux command to get the readiness tool directly. For example, you can use wget or curl to open the link https://aka.ms/microsofttunnelready.

     For example, to use wget and log details to mst-readiness during the download, run wget --output-document=mst-readiness https://aka.ms/microsofttunnelready

   The script can be run from any Linux server that's on the same network as the server you that you plan to install, which enables network admins to use the script to troubleshoot network issues independently.

2. To validate your network and Linux configuration, run the script with the following commands. These commands set the run permissions for the script, validate the Tunnel can connect to the correct endpoints, and then check for the presence of utilities that Tunnel uses:

   • sudo ./mst-readiness

   • sudo ./mst-readiness network - This command runs the following actions and then reports success or error for both:

     • Tries to connect to each Microsoft endpoint the tunnel will use.
     • Checks that the required ports are open in your firewall.

   • sudo ./mst-readiness utils - This command validates that utilities that are used by Tunnel like Docker or Podman and ip_tables are available.

3. To validate that the account you'll use to install Microsoft Tunnel has the required roles and permissions to complete enrollment, run the script with the following command line: ./mst-readiness account

   The script prompts you to use a different machine with a web browser, which you use to authenticate to Microsoft Entra ID and to Intune. The tool reports success or an error.

For more information about this tool, see Reference for mst-cli in the reference article for Microsoft Tunnel article.

Manually load ip_tables

While most Linux distributions automatically load the ip_tables module, some distributions might not. For example, RHEL 8.5 doesn't load the ip_tables by default.

To check for the presence of this module, run the most recent version of mst-readiness tool on the Linux server. The check for ip_tables was added to the readiness tools script on February 11 2022.

If the module isn't present, the tool stops on the ip_tables module check. In this scenario, you can run the following commands to manually load the module.

Manually load the ip_tables module

In the context of sudo, run the following commands on your Linux server:

1. Validate the presence of ip_tables on the server: lsmod |grep ip_tables

2. If ip_tables isn't present, run the following to load the module into the kernel immediately, without a restart: /sbin/modprobe ip_tables

3. Rerun the validation to confirm the tables are now loaded: lsmod |grep ip_tables

Configure Linux to load ip_tables at boot

In the context of sudo, run the following command on your Linux server to create a config file that loads the ip_tables into kernel during boot time: echo ip_tables > /etc/modules-load.d/mstunnel_iptables.conf

Manually load the tun module

Microsoft Tunnel requires the tun module, however some Linux distributions don't load the tun module by default.

To validate the present of the tun module on the server, run: lsmod |grep tun

1. If tun isn't present, run the following to load the module into the kernel immediately, without a restart: /sbin/modprobe tun

2. Rerun the validation to confirm the tun module is now loaded: lsmod |grep tun

Configure Linux to load tun at boot

In the context of sudo, run the following command on your Linux server to create a config file that loads tun into kernel during boot time: echo tun > /etc/modules-load.d/mstunnel_tun.conf

Next steps

Configure Microsoft Tunnel