wireguard-allowed-ips-csharp

A small CLI tool or library written in C# to calculate the AllowedIPs field of a wireguard config if you want to exclude certain IP-Ranges.

Inspired by (and used for test reference): https://krasovs.ky/2021/07/04/wireguard-allowed-ips.html

Table of contents

1. Dependencies
2. Releases
3. Usage
4. Usage within another C# application
5. Motivation
6. License

Dependencies

This program requires .NET 8. Other than that it was designed to require no other dependencies.

Releases

Executable files are provided for all major platforms. (Because why not :>)
All files ending in -selfcontained do not require the .NET 8 Runtime to be installed on the system. Though they are massively greater in filesize than the runtime dependent ones.

Usage

(Note: if you want to use dotnet run, make sure the terminal's working directory is WireguardAllowedIPs: cd WireguardAllowedIPs inside the reposity directory)

Upon running the program without arguments via dotnet run or via the precompiled executable, a help is displayed:

Usage: wireguard-allowed-ips [-h] [-a "all"|allowed-ranges] [-d disallowed-ranges]

Calculate the allowed ranges from an underlying allowed range
and disallowed ranges within that range.

Options:
 -h, --help             Displays this help.

 -a, --allowed          Set the allowed ip ranges in CIDR notation, separated by commas.
                        Default Value if omitted: All IPs are allowed (both IPv4 and IPv6).

 -d, --disallowed       Set the disallowed ip ranges in CIDR notation, separated by commas.

Make sure not to place spaces between multiple networks:
Incorrect: --disallowed 10.0.0.0/8, 192.168.0.0/16
Correct: --disallowed 10.0.0.0/8,192.168.0.0/16
The former only works if quoted:
--disallowed "10.0.0.0/8, 192.168.0.0/16"

By default, if no allowed IP-Ranges are supplied, all networks are included in the calculation (0.0.0.0/0, ::0/0).

Examples:
(Note: If you're using the precompiled executable, replace dotnet run with the name of the executable)

dotnet run --disallowed 10.0.0.0/8,192.168.0.0/16,72.8.99.100/32

0.0.0.0/5, 8.0.0.0/7, 11.0.0.0/8, 12.0.0.0/6, 16.0.0.0/4, 32.0.0.0/3, 64.0.0.0/5, 72.0.0.0/13, 72.8.0.0/18, 72.8.64.0/19, 72.8.96.0/23, 72.8.98.0/24, 72.8.99.0/26, 72.8.99.64/27, 72.8.99.96/30, 72.8.99.101/32, 72.8.99.102/31, 72.8.99.104/29, 72.8.99.112/28, 72.8.99.128/25, 72.8.100.0/22, 72.8.104.0/21, 72.8.112.0/20, 72.8.128.0/17, 72.9.0.0/16, 72.10.0.0/15, 72.12.0.0/14, 72.16.0.0/12, 72.32.0.0/11, 72.64.0.0/10, 72.128.0.0/9, 73.0.0.0/8, 74.0.0.0/7, 76.0.0.0/6, 80.0.0.0/4, 96.0.0.0/3, 128.0.0.0/2, 192.0.0.0/9, 192.128.0.0/11, 192.160.0.0/13, 192.169.0.0/16, 192.170.0.0/15, 192.172.0.0/14, 192.176.0.0/12, 192.192.0.0/10, 193.0.0.0/8, 194.0.0.0/7, 196.0.0.0/6, 200.0.0.0/5, 208.0.0.0/4, 224.0.0.0/3, ::/0

---

dotnet run --allowed 198.18.0.0/15 --disallowed 198.18.15.0/24

198.18.0.0/21, 198.18.8.0/22, 198.18.12.0/23, 198.18.14.0/24, 198.18.16.0/20, 198.18.32.0/19, 198.18.64.0/18, 198.18.128.0/17, 198.19.0.0/16

---

You can mix IPv4 and IPv6 to your liking, the application will group them accordingly.

dotnet run --allowed 198.0.0.0/8,f000::/4 --disallowed fe80:abcd::/32,198.18.15.0/24

198.0.0.0/12, 198.16.0.0/15, 198.18.0.0/21, 198.18.8.0/22, 198.18.12.0/23, 198.18.14.0/24, 198.18.16.0/20, 198.18.32.0/19, 198.18.64.0/18, 198.18.128.0/17, 198.19.0.0/16, 198.20.0.0/14, 198.24.0.0/13, 198.32.0.0/11, 198.64.0.0/10, 198.128.0.0/9, f000::/5, f800::/6, fc00::/7, fe00::/9, fe80::/17, fe80:8000::/19, fe80:a000::/21, fe80:a800::/23, fe80:aa00::/24, fe80:ab00::/25, fe80:ab80::/26, fe80:abc0::/29, fe80:abc8::/30, fe80:abcc::/32, fe80:abce::/31, fe80:abd0::/28, fe80:abe0::/27, fe80:ac00::/22, fe80:b000::/20, fe80:c000::/18, fe81::/16, fe82::/15, fe84::/14, fe88::/13, fe90::/12, fea0::/11, fec0::/10, ff00::/8

Usage within another C# application

The namespace WireguardAllowedIPs.Core (Directory) contains all necessary tools to calculate AllowedIPs.

Example Code: (Demo.cs)

string[] allowedIPs = new[] {
    "0.0.0.0/0",
    "::/0"
};
string[] disallowedIPs = new[] {
    "10.0.0.0/8",
    "192.168.0.0/16",
    "172.16.0.0/12",
    "72.8.99.100/32"
};

// Calculate AllowedIPs based on the values above
IPNetwork[] result = Calculator.CalculateAllowedIPs(allowedIPs, disallowedIPs);

// The IP-Types have implementations for ToString
Console.WriteLine($"AllowedIPs = {string.Join<IPNetwork>(",", result)}");

Motivation

I was not able to find straightforward code which shows how to replicate the results found on https://krasovs.ky/2021/07/04/wireguard-allowed-ips.html
(The code is written in Go and uses the go4.org/netipx package internally)

I needed a way to compute AllowedIPs dynamically myself. And also within a C# application. So I decided to do some research and write a small library for exactly that purpose!

License

This project is licensed under the MIT license.