Tag: WireGuard

Creating a WireGuard profile for Cloudflare Warp

Connecting to Cloudflare Warp directly via wg can have advantages in flexibility or specific scenarios. For example, the Warp client, warp-cli would refuse to establish connection if it can’t override /etc/resolve.conf. By connecting directly using WireGuard, you get control over all that.

The first step is to install warp-cli and register using warp-cli register. This will create the WireGuard private-key used for the connection and register it with Cloudflare. The private key can be found in /var/lib/cloudflare-warp/reg.json. The endpoint data and Cloudflare’s public key should be constant. Alternative endpoints are listed in /var/lib/cloudflare-warp/conf.json.

An easy way to read the json configuration files is using jq:

$ sudo jq . /var/lib/cludflare-warp-/conf.json

Adjust the following template accordingly, and put in int /etc/wireguard/warp.conf:

[Interface]
PrivateKey = XXXXXXXXXXXX  
Address = 172.16.0.2/32
Address = 2606:4700:110:892f:607d:85a6:5e07:70cf/128
[Peer]
PublicKey = bmXOC+F1FxEMF9dyiK2H5/1SUtzH0JuVo51h2wPfgyo=
AllowedIPs = 0.0.0.0/0, ::/0
Endpoint = engage.cloudflareclient.com:2408

You can start the tunnel using

$ sudo wg-quick up warp`

Alternatively, you can import it to NetworkManager and be able to easily start it from the Gnome Quick Settings.

$ sudo nmcli connection import type wireguard file /etc/wireguard/warp.conf

You can easily check that the tunnel works, by visiting https://www.cloudflare.com/cdn-cgi/trace/ and looking for the line that says warp=on.

Sometimes, IPv4 won’t work while IPv6 works. Restarting the VPN several times can resolve the issue.

while ! ping -w1 -c1 1.1.1.1; do wg-quick down wgcf-profile; wg-quick up wgcf-profile; done

or using nmcli:

while ! ping -w1 -c1 1.1.1.1; do nmcli connection down wgcf-profile; nmcli connection up wgcf-profile; done

Disabling the Cloudflare client

The Cloudflare client might interfere with the Wireguard profile. It’s best to didable it:

$ sudo systemctl disable --now  warp-svc.service
$ systemctl --user disable --now warp-taskbar.service

Setting up WireGuard on Debian

WireGuard is a modern VPN solution, which is much easier to configure than OpenVPN and its likes. In this tutorial, we assume a simple setup where we want to route all clients network traffic through the VPN, exiting through the server.

Server configuration

$ sudo apt install wireguard
$ PRIVATE_KEY=$(wg genkey)

Now we create the configuration file for our tunnel (wg0).

$ cat <<EOF | sudo tee /etc/wireguard/wg0.conf
[Interface]
PrivateKey = $PRIVATE_KEY
Address = 10.8.0.1/24, fd0d:d325:45c0::1/64
ListenPort = 51820
SaveConfig = true

PostUp = iptables -t nat -I POSTROUTING -o eth0 -j MASQUERADE
PostUp = ip6tables -t nat -I POSTROUTING -o eth0 -j MASQUERADE
PreDown = iptables -t nat -D POSTROUTING -o eth0 -j MASQUERADE
PreDown = ip6tables -t nat -D POSTROUTING -o eth0 -j MASQUERADE
EOF

If you have a firewall, you’ll need to open up UDP port 51820 (or whatever configured as the ListenPort).

Enable IPv4 and IPv6 forwarding, so we can route all the client traffic through the server (and reload sysctl configuration)

$ echo net.ipv4.ip_forward=1 | sudo tee /etc/sysctl.d/40-wireguard.conf
$ echo net.ipv6.conf.all.forwarding=1 | sudo tee -a /etc/sysctl.d/40-wireguard.conf
$ sudo sysctl --system

Enable and start the WireGuard service:

$ sudo systemctl enable --now wg-quick@wg0.service

Finally, take note of the server public key (it will be a short base64 encoded string):

$ echo $PRIVATE_KEY | wg pubkey

You’ll need it in the next step.

Peer configuration

$ sudo apt install wireguard
$ PRIVATE_KEY=$(wg genkey)
$ PUBLIC_KEY=$(echo $PRIVATE_KEY | wg pubkey)
$ SERVER_PUBLIC_KEY=6TDw+U2WFhkaKUy/xXrCRtuZvB2m2SFN7URZA5AkGis=
$ SERVER_IP=8.8.8.8

Replace the value of SERVER_PUBLIC_KEY with the public key of your server, and SERVER_IP with the correct IP address of your server.

Edit /etc/wireguard/wg0.conf

$ cat <<EOF | sudo tee /etc/wireguard/wg0.conf
[Interface]
PrivateKey = $PRIVATE_KEY
Address = 10.8.0.2/24, fd0d:d325:45c0::2/64

[Peer]
PublicKey = $SERVER_PUBLIC_KEY
AllowedIPs = 0.0.0.0/0, ::/0
Endpoint = $SERVER_IP:51820
EOF

Setting AllowedIPs = 0.0.0.0/0, ::/0 will route all traffic through the VPN connection. If you don’t want to do that, edit the configuration file, and set AllowedIPs = 10.8.0.0/24, fd0d:d325:45c0::0/64.

We need to make the server aware of the peer. The following command should be executed on the server.

$ sudo wg set wg0 peer $PUBLIC_KEY allowed-ips 10.8.0.2,fd0d:d325:45c0::2

where PUBLIC_KEY is the value of the client’s public key (stored in the $PUBLIC_KEY environment variable).

The /etc/wireguard/wg0.conf will be updated according and make the added peer configuration persistent due to the SaveConfig = true. The configuration update will take place the next time the WireGuard interface goes down.

You can also import the profile into NetworkManager and easily enable/disable the new interface via GNOME:

$ sudo nmcli connection import type wireguard file /etc/wireguard/wg0.conf

Android Peer

It is also useful to have WireGuard on the phone. WireGuard supports both iOS and Android, and the setup should be similar in both cases. Start by installing WireGuard from the Play Store. The next step is to generate the required configuration. It can be done directly on the phone, or by creating a configuration file on your computer and transferring it, which I find simpler.

$ PRIVATE_KEY=$(wg genkey)
$ PUBLIC_KEY=$(echo $PRIVATE_KEY | wg pubkey)
$ SERVER_PUBLIC_KEY=6TDw+U2WFhkaKUy/xXrCRtuZvB2m2SFN7URZA5AkGis=
$ SERVER_IP=8.8.8.8
$ cat <<EOF > wg0.conf
[Interface]
PrivateKey = $PRIVATE_KEY
Address = 10.8.0.3/24, fd0d:d325:45c0::3/64

[Peer]
PublicKey = $SERVER_PUBLIC_KEY
AllowedIPs = 0.0.0.0/0, ::/0
Endpoint = $SERVER_IP:51820
EOF

Again, make the server aware of the client by running the following command on the server:

$ sudo wg set wg0 peer $PUBLIC_KEY allowed-ips 10.8.0.3,fd0d:d325:45c0::3

Transfer the configuration file wg0.conf to the phone and load it using the WireGuard app.

Update 2023-11-30: Added IPv6 configuration.