A point to Site topology connects a machine (let's call it foo) to a network using VPN.

To achieve this, in most cases you can make this connection between foo and a local machine bar on the desired network directly (with the help of port forwarding) but in some cases this network can be behind a Carrier-Grade NAT CG-NAT, this repo is here to help you in this situation.

We will use a VPS to run a VPN Server that is publicly accessible, then we can connect to that server from foo and bar and with some tweaks we can make foo not only communicate with bar but also with bar's local area network.

• first, install WireGuard from the package manager.

  Ubuntu / Debian :

  sudo apt install wireguard
  

  Arch :

  sudo pacman -S wireguard-tools
  

  if you've chosen a different distro you can always seek guidence from WireGuard's website.

• then, generate public and private keys using this command:

  wg genkey | tee privatekey | wg pubkey > publickey
  

  you will have those keys generated in the current folder (directory).

• Use middle_server/wg1.conf file as a template and copy it to /etc/wireguard (may require root privileges).

• Allow port 51820 udp on the firewall to accept connections from anywhere.

• Install WireGuard on your machine.
• Generate public and private keys using the same command (if you are using windows don't use cmd , use powershell instead to generate the keys).
• Use foo/wg1.conf file as a template and copy it to /etc/wireguard (if you are using windows import the config file into the WireGuard application).

• Do exactly the same as before (on foo configuration).
• If bar is not the default gateway of its network then add a static route to the gateway (R1 in the figure) to forward 10.8.0.0/24 packets to bar.

After configuring the machines you can now establish a connection using this command:

sudo wg-quick up wg1

(if you are using windows press the Activate button on the WireGuard application).

If everything is configured properly you can now access any service running on bar's network from foo.

If you're having any issues connecting to the VPN server even though you're sure everything is configured properly then one of the reasons is that your country is probably applying Deep Packet Inspection DPI which gives them the power to distinguish WireGuard traffic and drop it.

• DPI: https://en.wikipedia.org/wiki/Deep_packet_inspection
• CG-NAT: https://www.sidn.nl/en/news-and-blogs/cgnat-frustrates-all-ip-address-based-technologies
• WireGuard: https://www.wireguard.com/
• Point to Site topolgy (Routing): https://www.procustodibus.com/blog/2021/04/wireguard-point-to-site-routing/
• Point to Site topology (Masquerading): https://www.procustodibus.com/blog/2020/11/wireguard-point-to-site-config/
• Point to Site topology (Port Forwarding): https://www.procustodibus.com/blog/2021/04/wireguard-point-to-site-port-forwarding/
• Point to Site topology (Site Gateway): https://www.procustodibus.com/blog/2021/04/wireguard-point-to-site-gateway/