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Wireless LAN routing

wlan-routing

Overview

Experimental ยท Insiders only

RaspAP is often used to share internet from an Ethernet connection or other network device through a wireless access point (AP), or act as a wireless repeater. However, in certain scenarios, it can be extremely useful to share internet from a wireless LAN (WLAN) with clients connected via an Ethernet or USB-Ethernet connection. Many RaspAP users have requested this functionality, so an easy-to-use solution was developed to fulfill this need.

Solution

To create this setup, the target interface must be configured with a static IP address and have DHCP enabled. This is similar to how RaspAP's default wireless access point is configured. To simplify this process, RaspAP uses predefined subnets for the eth0 and predictable enx interfaces. The relevant portions of this configuration are shown below:

"dhcp": {
    ...
    "eth0": {
      "static ip_address": [ "192.168.55.1/24" ],
      "static routers": [ "192.168.55.1" ],
      "static domain_name_server": [ "1.1.1.1 8.8.8.8" ],
      "subnetmask": [ "255.255.255.0" ]
    },
    "enx": {
      "static ip_address": [ "192.168.60.1/24" ],
      "static routers": [ "192.168.60.1" ],
      "static domain_name_server": [ "1.1.1.1 8.8.8.8" ],
      "subnetmask": [ "255.255.255.0" ]
    }

"dnsmasq": {
    ...
    "eth0": {
      "dhcp-range": [ "192.168.55.50,192.168.55.150,12h" ]
    },
    "enx": {
      "dhcp-range": [ "192.168.60.50,192.168.60.150,12h" ]
    }
  }

These default settings are applied automatically, however you may modify them as you wish from the DHCP Server administration page.

In addition to these settings, Network Address Translation (NAT) rules must be applied to enable packet routing between the desired interfaces. These iptables rules also need to be added when the connection is active, and removed when the connection is deactivated. This is roughly analogous to how WireGuard's PostUp and PostDown rules function.

Steps to enable WLAN routing

wlan-routing-diagram

Configure wireless client

To create this configuration, begin by configuring your device as a wireless client, or station, with RaspAP's WiFi client page or by preconfiguring your OS for wireless LAN operation. Optionally, connect an external wireless adapter to an available USB port.

Check wireless connectivity

Ensure that you have a stable wireless connection to your router. The Wireless Client widget on RaspAP's dashboard will indicate its status and link quality. wifi-client

Attach Ethernet or USB-Ethernet adapter

Next, attach an Ethernet cable or a USB-Ethernet adapter to an available port, and connect a device you wish to provide internet connectivity to. This could be a laptop, hub or other Ethernet-capable network device. This device will typically be assigned a network interface name by the operating system, such as eth0 or eth1. If your system is configured to use predictable interface names, it may incorporate the interfaces's MAC address (for example, enx78e7d1ea46da).

Verify your attached device by checking the output on RaspAP's Networking > Summary tab.

Tip

adapter Many USB-Ethernet adapters are available at low cost. If you choose this option, buy one from a reputable brand. When in doubt, verify your adapter by testing it with a laptop or other device. Note that a regular USB cable, rather than a USB-Ethernet adapter, is not designed for direct Ethernet communication.

Configure RaspAP's settings

Now, from RaspAP's Networking > WLAN Routing tab, choose your wireless client interface and output interface (typically, eth0 or enx). Select the "Configure a static IP address and DHCP for output interface" option toggle, choose Save settings and lastly Start WLAN routing.

wlan-routing

A system configured with predictable interface names is shown, above.

Note

If a wireless client connection is not detected on your system, it will be indicated as "not configured" in the interface. The Start WLAN routing button will also be disabled until an active wireless client connection is present.

Check ethernet connectivity

Finally, confirm internet connectivity on your Ethernet-equipped client device. Optionally, you may wish to perform a speed test. If you want to stop wireless LAN routing, simply choose Stop WLAN routing. The iptables NAT rules added by RaspAP will be removed from your system. The associated DHCP and dnsmasq configurations will be removed as well.

Tip

RaspAP's default subnets are added for convenience. If you wish to create a custom configuration for your clients, you may do so from the DHCP Server page. Be sure to Save settings and restart dsnmasq to apply your changes. If your interface is named something other than eth0 or enx you must create your own DHCP configuration.

Troubleshooting

If clients do not have internet connectivity, ensure that the attached Ethernet device appears on the Networking > Summary tab. Faulty Ethernet cables and USB-Ethernet adapters are common culprits.

Be sure that you've selected the option to configure a static IP address and DHCP for the output interface on the Networking > WLAN Routing tab. If you've configured your own subnet for this purpose, ensure that the settings are correct on the DHCP server page and that the dnsmasq service was restarted after saving them.

Finally, while wireless LAN routing is active, you may confirm that the iptables NAT rules are active by executing the following:

sudo iptables -t nat -L -v

This should output the POSTROUTING, MASQUERADE and FORWARD rules for the interfaces you've selected. If not, confirm that this option is active on the Networking > WLAN Routing tab, then choose Restart WLAN routing.

Discussions

Questions or comments about using wireless LAN routing? Join the discussion here.