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Subnet routers and traffic relay nodes

Subnet routers are available for all plans.

Tailscale works best when you install the Tailscale client on every client, server, and virtual machine (VM) in your organization. This enforces end-to-end traffic encryption without additional configuration to move machines between physical locations.

In some situations, you can't or don't want to install Tailscale on each device:

  • With embedded devices, like printers, which don't run external software.
  • When connecting large quantities of devices, like an entire AWS VPC.
  • When incrementally deploying Tailscale (for example, on legacy networks).

In these cases, you can set up a "subnet router" (previously called a relay node) to access these devices from Tailscale. Subnet routers act as a gateway, relaying traffic from your Tailscale network to your physical subnet. Subnet routers respect features like access control policies, which make it easy to migrate a large network to Tailscale without installing the Tailscale client on every device.

Devices behind a subnet router do not count toward your pricing plan's device limit. However, installing Tailscale directly on devices wherever possible offers better performance, security, and a zero-configuration setup.

Set up a subnet router

To activate a subnet router on a Linux, macOS, tvOS, or Windows machine:

  1. Install the Tailscale client.
  2. Connect to Tailscale as a subnet router.
  3. Enable subnet routes from the admin console.
  4. Add access rules for advertised subnet routes.
  5. Verify your connection.
  6. Use your subnet routes from other devices.

Install the Tailscale client

Connect to Tailscale as a subnet router

After the installation completes, you can start (or restart) Tailscale as a subnet router:

This feature requires IP forwarding to be enabled.

Enable IP forwarding

If your Linux system has a /etc/sysctl.d directory, use:

echo 'net.ipv4.ip_forward = 1' | sudo tee -a /etc/sysctl.d/99-tailscale.conf
echo 'net.ipv6.conf.all.forwarding = 1' | sudo tee -a /etc/sysctl.d/99-tailscale.conf
sudo sysctl -p /etc/sysctl.d/99-tailscale.conf

Otherwise, use:

echo 'net.ipv4.ip_forward = 1' | sudo tee -a /etc/sysctl.conf
echo 'net.ipv6.conf.all.forwarding = 1' | sudo tee -a /etc/sysctl.conf
sudo sysctl -p /etc/sysctl.conf

If your Linux node uses firewalld, you might need to allow masquerading due to a known issue. As a workaround, you can allow masquerading with this command:

firewall-cmd --permanent --add-masquerade

Other Linux distributions might require different steps.

When enabling IP forwarding, ensure your firewall is set up to deny traffic forwarding by default. This is a default setting for common firewalls like ufw and firewalld. Denying traffic forwarding by default ensures your device doesn't route traffic unintentionally.

sudo tailscale up --advertise-routes=192.168.0.0/24,192.168.1.0/24

Replace the subnets in the example above with the right ones for your network. Both IPv4 and IPv6 subnets are supported.

If the device is authenticated by a user who can advertise the specified route in autoApprovers, then the subnet router's routes will automatically be approved. You can also advertise any subset of the routes allowed by autoApprovers in the tailnet policy file.

If you'd like to expose default routes (0.0.0.0/0 and ::/0), consider using exit nodes instead.

Enable subnet routes from the admin console

This step is not required if you use autoApprovers.

  1. Open the Machines page of the admin console.
  2. Locate the Subnets badge in the machines list or use the property:subnet filter to list all devices advertising subnet routes.
  3. Select a machine with the subnet property, then navigate to the Routing Settings section.
  4. Select Edit. This opens the Edit route settings panel.
  5. Under Subnet routes, select the routes to approve, then select Save.

You might prefer to disable key expiry on your server to avoid having to periodically reauthenticate. Refer to key expiry for more information about machine keys and how to disable their expiry. If you are using ACL tags, key expiry is disabled by default.

Add access rules for the advertised subnet routes

This step is not required if you already have rules that allow access to your advertised subnet routes.

  1. Open the Access Controls page of the admin console to update your tailnet policy file.
  2. Create an access rule that allows access to the advertised subnet.

What this access rule does:

  • Members of the development team group:dev can access devices in the subnets 192.168.0.0/24 and 192.168.1.0/24.
  • The subnet 192.168.0.0/24 can access the subnet 192.168.1.0/24 and vice versa, if subnet route masquerading is disabled.
{
  "groups": {
    "group:dev": ["alice@example.com", "bob@example.com"]
  },
  "acls": [
    // Users in group:dev and devices in subnets 192.168.0.0/24 and
    // 192.168.1.0/24 can access devices in subnets 192.168.0.0/24 and
    // 192.168.1.0/24
    { "action": "accept",
      "src": ["group:dev","192.168.0.0/24", "192.168.1.0/24"],
      "dst": ["192.168.0.0/24:*", "192.168.1.0/24:*"]
    }
  ]
}

Select Save on your tailnet policy file so the Tailscale coordination server distributes the updated policy to the nodes in your tailnet.

Verify your connection

Check that you can ping the Tailscale IP address of your new subnet routers from your personal Tailscale device (such as a Linux, macOS, or Windows device). You can find the Tailscale IP in the admin console or by running the following command on the subnet router.

tailscale ip -4

Use your subnet routes from other machines

Clients on Android, iOS, macOS, tvOS, and Windows automatically pick up your new subnet routes.

Only Linux clients using the --accept-routes flag discover the new routes automatically because the default is to use only the Tailscale IP addresses. You can enable automatic route discovery on Linux by running the following command:

sudo tailscale up --accept-routes

Update subnet routes

To update subnet routes:

  1. Connect to Tailscale as a subnet router.
  2. Enable subnet routes from the admin console.
  3. Add access rules for advertised subnet routes.
  4. Verify your connection.
  5. Use your subnet routes from other devices.

Previously enabled routes that you exclude when enabling subnet routes will no longer appear as advertised. You can remove unused routes or keep them enabled if you plan to re-advertise them.

Route DNS lookups to an internal DNS server

You can add Tailscale IPs to public DNS records because Tailscale IPs are only accessible to authenticated users of your network. You can use an internal DNS server on your subnet by configuring split DNS in the DNS page of the admin console.

Set up high availability

You can set up high availability to ensure your network is connectable even if one subnet router goes offline. For more information, refer to our article on high availability failover.