WireGuard Server for Windows

WS4W is a desktop application that allows running and managing a WireGuard server endpoint on Windows.

Inspired by Henry Chang's post, How to Setup Wireguard VPN Server On Windows, my goal was to create an application that automated and simplified many of the complex steps. While still not quite a plug-and-play solution, the idea is to be able to perform each of the prerequisite steps, one-by-one, without running any scripts, modifying the Registry, or entering the Control Panel.

What Does It Do?

Below are the tasks that can be performed automatically using this application. Jump to How to Use.

Before

Download and Install WireGuard

This step downloads and runs the latest version of WireGuard for Windows from https://download.wireguard.com/windows-client/wireguard-installer.exe. Once installed, it can be uninstalled directly from WS4W, too.

Server Configuration

Here you can configure the server endpoint. See the WireGuard documentation for the meaning of each of these fields. The Private Key, Public Key, and Preshared Key are generated by calling wg genkey, wg pubkey [private key], and wg genpsk, respectively.

Note: It is important that the server's network range not conflict with the host system's IP address or LAN network range.

In addition to creating/udpating the configuration file for the server endpoint, editing the server configuration will also update the ScopeAddress registry value (under HKLM\SYSTEM\CurrentControlSet\Services\SharedAccess\Parameters). This is the IP address that is used for the WireGuard adapter when using the Internet Sharing feature (explained here). Thus, the Address property of the server configuration serves to determine the allowable addresses for clients, as well as the IP that Windows will assign to the WireGuard adapter when performing Internet Sharing. Note the IP address is grabbed from the ScopeAddress at the time when Internet Sharing is first performed. That means that if the server's IP address is changed in the configuration (and thus the ScopeAddress registry value is updated), the WireGuard interface will no longer accurately reflect the desired server IP. Therefore, WS4W will prompt to re-share internet. If canceled, Internet Sharing will be disabled and will have to be re-enabled manually.

Important: You must configure port forwarding on your router. Forward all UDP traffic that is destined for your server endpoint port (default 51820) to the LAN IP of your server. Every router is different, so it is difficult to give specific guidance here. As an example, here is what the port forwarding rule would look like on a Verizon Quantum Gateway router.

You should set the Endpoint property to your public IPv4, IPv6, or domain address, followed by whatever port you have forwarded. The Detect Public IP Address button will attempt to detect your public address automatically using the ipify.org API. However, if possible, it is recommended that you use a domain name with DDNS. That way, if your public IP address changes, your clients will be able to find your server endpoint without reconfiguration.

Client Configuration

Here you can configure the client(s). The Address can be entered manually or calculated based on the server's network range. For example, if the server's network is 10.253.0.0/24, the client config can determine that 10.253.0.2 is a valid address. Note that the first address in the range (in this case, 10.253.0.1) is reserved for the server. DNS is optional, but recommended. Lastly, the Private Key and Public Keys are again generated using wg genkey and wg pubkey [private key]. However, the Preshared Key must match the server's. If it has already been generated in the server config, it can be automatically copied to the client config.

Once configured, it's easy to import the configuration into your client app of choice via QR code or by exporting the .conf file.

Tunnnel Service

Once the server and client(s) are configured, you may install the tunnel service, which creates a new network interface for WireGuard using the wireguard /installtunnelservice command. After installation, the tunnel may be also removed directly within WS4W. This uses the wireguard /uninstalltunnelservice command.

Installing the tunnel service should be sufficient to perform a WireGuard handshake.

Note: If the server configuration is edited after the tunnel service is installed, the tunnel service will automatically be updated via the wg syncconf command (if the newly saved server configuration is valid). This is also true of the client configurations, updates to which often cause the server configuration to be updated (e.g., if a new client is added, the server configuration must be aware of this new peer).

Private Network

Even after the tunnel service is installed, some protocols may be blocked. It is recommended to change the network profile to Private, which eases Windows restrictions on the network.

Note: On a system where the shared internet connection originates from a domain network, this step is not necessary, as the WireGuard interfaces picks up the profile of the shared domain network.

Internet Sharing

Perhaps most importantly, internet sharing must be enabled in order to provide a real network connection to the WireGuard interface. In Windows, this is accomplished using Internet Connection Sharing, which serves as NAT router between the system's public network and the devices connected to the WireGuard interface.

When configuring this option, you may select any of your network adapters to share. Note that it will likely only work for adapters whose status is Connected, and it will only be useful for adapters which provide internet or LAN access.

Note: When performing internet sharing, the WireGuard adapter is assigned an IP from the ScopeAddress registry value (under HKLM\SYSTEM\CurrentControlSet\Services\SharedAccess\Parameters). This value is automatically set when updating the Address property of the server configuration. See more here.

Persistent Internet Sharing

There is a known bug in Windows that causes Internet Sharing to become disabled after a reboot. If the WireGuard server is intended to be left unattended, it is recommended to enable Persistent Internet Sharing so that no interaction is required after rebooting.

When enabling this feature, two steps are performed.

The Internet Connection Sharing service startup mode is changed from Manual to Automatic.
The value of the EnableRebootPersistConnection regstry value in HKLM\Software\Microsoft\Windows\CurrentVersion\SharedAccess is set to 1 (it is created if not found).

Warning: This feature is currently unreliable due to Windows bugs, and may not consistently preserve internet sharing through reboots. To ensure that Internet Sharing is enabled after a reboot, see Internet Sharing Workaround.

View Server Status

Once the tunnel is installed, the status of the WireGuard interface may be viewed. This is accomplished via the wg show command. It will be continually updated as long as Update Live is checked.

After

How to Use

The latest release is available here. Download Portable.zip, and extract all.

GUI

After extracing the zip, run WireGuardServerForWindows.exe. Feel free to make a shortcut in %programdata%\Microsoft\Windows\Start Menu\Programs to add the application to your Start Menu.

If you get the following prompt, say Yes.

When the .NET Core download page opens, choose the x64 download for "desktop apps".

An enhancement to create a proper installer, which would handle dependencies like these, is being tracked in #6.

Note: The application will request to run as Administrator. Due to all the finagling of the registry, Windows services, wg.exe calls, etc., it is easier to run the whole application elevated.

CLI

There is also a CLI bundled in the portable download called ws4w.exe which can be invoked from a terminal or included in a script. In addition to messages written to standard out, the CLI will also set the exit code based on the success of executing the given command. In PowerShell, for example, the exit code can be printed with echo $lastexitcode.

Note: The CLI must also be run as an Administrator for the same reasons as above.

Usage

The CLI uses verbs, or top-level commands, each of which has its own set of options. You can run ws4w.exe --help for a list of all verbs or ws4w.exe verb --help to see the list of options for a particular verb.

List of Supported Verbs

ws4w.exe restartinternetsharing [--network <NETWORK_TO_SHARE>]
- This will tell WS4W to attempt to restart the Internet Sharing feature.
- The --network option may be passed to specify which network WS4W should share.
- If Internet Sharing is already enabled, WS4W will attempt to reshare the same network (unless --network is passed).
- If multiple networks are already shared, it is not possible to tell which one is shared with the WireGuard network, so the --network option must be passed to specify.
- If Internet Sharing is not already enabled, the --network option must be passed, otherwise there is no way to know which network to share.
- The exit code will be 0 if the requested or previously shared network was successfully reshared.

Known Issues

Even following the steps in Henry's guide, the Persistent Internet Sharing feature is unreliable. A reboot may still cause the the internet sharing to fail, even though the Internet Connection Sharing service is running, and the network interface indicates that it is sharing in Control Panel. Only unsharing and resharing can fix this.

Internet Sharing Workaround

Fortunately, the CLI makes the process of unsharing and resharing easy to automate. Following is an example using the Windows Task Scheduler.

Create a task which runs whether or not the user is logged in.
Set the task to be triggered by system startup.
Add an action that starts ws4w.exe with the restartinternetsharing verb.

Goals

One of the more lofty goals of this project was to run a VPN behind NAT without port forwarding. I am interested by Jordan Whited's post, WireGuard Endpoint Discovery and NAT Traversal using DNS-SD and hope to investigate the possibility of integrating it into this application at some point.

NULL0B/WireGuardServerForWindows