This tutorial is going to show you how to set up your own WireGuard VPN server on Debian. WireGuard is made specifically for the Linux kernel. It runs inside the Linux kernel and allows you to create fast, modern, and secure VPN tunnel.
Features of WireGuard VPN
- Lightweight and super fast speed, blowing OpenVPN out of the water.
- Cross-platform. WireGuard can run on Linux, BSD, macOS, Windows, Android, iOS, and OpenWRT.
- User authentication is done by exchanging public keys, similar to SSH keys.
- It assigns static tunnel IP addresses to VPN clients. Some folks may not like it, but it can be useful in some cases.
- Mobile devices can switch between Wi-Fi and mobile network seamlessly without dropping any connectivity.
- It aims to replace OpenVPN and IPSec in most use cases.
Prerequisites
This tutorial assumes that the VPN server and VPN client are both running Debian operating system.
Step 1: Install WireGuard on Debian Server and Desktop
Log into your Debian server. WireGuard is included in the Debian 11 (Bullseye) repository, so you can run the following commands to install it.
sudo apt update sudo apt install wireguard wireguard-tools linux-headers-$(uname -r)
Debian 10 users need to add the backport repository with the following command.
echo "deb http://deb.debian.org/debian buster-backports main" | sudo tee /etc/apt/sources.list.d/buster-backports.list
Then install WireGuard.
sudo apt update sudo apt -t buster-backports install wireguard wireguard-tools wireguard-dkms linux-headers-$(uname -r)
Use the same commands to install WireGuard on your local Debian computer (the VPN client). Note that you also need to install the openresolv package on the client to configure DNS server.
sudo apt install openresolv
Step 2: Generate Public/Private Keypair
Server
Run the following command on the Debian server to create a public/private key pair, which will be saved under /etc/wireguard/ directory.
wg genkey | sudo tee /etc/wireguard/server_private.key | wg pubkey | sudo tee /etc/wireguard/server_public.key
Client
Run the following command to create a public/private key pair on the local Debian computer (the VPN client).
wg genkey | sudo tee /etc/wireguard/client_private.key | wg pubkey | sudo tee /etc/wireguard/client_public.key
Step 3: Create WireGuard Configuration File
Server
Use a command-line text editor like Nano to create a WireGuard configuration file on the Debian server. wg0 will be the network interface name.
sudo nano /etc/wireguard/wg0.conf
Copy the following text and paste it to your configuration file. You need to use your own server private key and client public key.
[Interface] Address = 10.10.10.1/24 SaveConfig = true PrivateKey = KIWV46zRQIFUu4qrffNBB23yuaST99PLCC3zigPbsGc= ListenPort = 51820 [Peer] PublicKey = 75VNV7HqFh 3QIT5OHZkcjWfbjx8tc6Ck62gZJT/KRA= AllowedIPs = 10.10.10.2/32
Where:
- Address: Specify the private IP address of the VPN server. Here I’m using the 10.10.10.0/24 network range. 10.10.10.1 is the private IP address for the VPN server.
- SaveConfig: the configuration should be saved on shutdown using the current status of the interface.
- PrivateKey: The private key of VPN server, which can be found in the
/etc/wireguard/server_private.keyfile on the server. - ListenPort: WireGuard VPN server will be listening on UDP port 51820, which is the default.
- PublicKey: The public key of VPN client, which can be found in the
/etc/wireguard/client_public.keyfile on the client computer. - AllowedIPs: IP addresses the VPN client is allowed to use. In this example, the client can only use the 10.10.10.2 IP address inside the VPN tunnel.
Save and close the file. (To save a file in Nano text editor, press Ctrl O, then press Enter to confirm. Press Ctrl X to exit.)
Change the file permission mode so that only root user can read the files.
sudo chmod 600 /etc/wireguard/ -R
Client
Use a command-line text editor like Nano to create a WireGuard configuration file on your local Debian computer. wg-client0 will be the network interface name.
sudo nano /etc/wireguard/wg-client0.conf
Copy the following text and paste it to your configuration file. You need to use your own client private key and server public key.
[Interface] Address = 10.10.10.2/24 DNS = 10.10.10.1 PrivateKey = cOFA x5UvHF a3xJ6enLatG DoE3I5PhMgKrMKkUyXI= [Peer] PublicKey = kQvxOJI5Km4S1c7WXu2UZFpB8mHGuf3Gz8mmgTIF2U0= AllowedIPs = 0.0.0.0/0 Endpoint = 12.34.56.78:51820
Where:
- Address: Specify the private IP address of the VPN client.
- DNS: specify 10.10.10.1 (VPN server) as the DNS server. It will be configured via the
resolvconfcommand. - PrivateKey: The client’s private key, which can be found in the
/etc/wireguard/client_private.keyfile on the client computer. - PublicKey: The server’s public key, which can be found in the
/etc/wireguard/server_public.keyfile on the server. - AllowedIPs: 0.0.0.0/0 represents the whole Internet, which means all traffic to the Internet should be routed via the VPN.
- Endpoint: The public IP address and port number of VPN server. Replace 12.34.56.78 with your server’s real public IP address.
Save and close the file.
Change the file mode so that only root user can read the files.
sudo chmod 600 /etc/wireguard/ -R
Step 4: Enable IP Forwarding on the Server
In order for the VPN server to route packets between VPN clients and the Internet, we need to enable IP forwarding. Edit sysctl.conf file.
sudo nano /etc/sysctl.conf
Add the following line at the end of this file.
net.ipv4.ip_forward = 1
Save and close the file. Then apply the changes with the below command. The -p option will load sysctl settings from /etc/sysctl.conf file. This command will preserve our changes across system reboots.
sudo sysctl -p
Step 5: Configure IP Masquerading on the Server
We need to set up IP masquerading in the server firewall, so that the server becomes a virtual router for VPN clients. I will use UFW, which is a front end to the iptables firewall. Install UFW on Debian with:
sudo apt install ufw
First, you need to allow SSH traffic.
sudo ufw allow 22/tcp
Then edit /etc/default/ufw file.
sudo nano /etc/default/ufw
Change the default forward policy from “DROP” to “ACCEPT”.
DEFAULT_FORWARD_POLICY="ACCEPT"
Save and close the file. Next, find the name of your server’s main network interface.
ip addr
As you can see, it’s named ens3 on my Debian server.
To configure IP masquerading, we have to add iptables command in a UFW configuration file.
sudo nano /etc/ufw/before.rules
By default, there are some rules for the filter table. Add the following lines at the end of this file. Replace ens3 with your own network interface name.
# NAT table rules
*nat
:POSTROUTING ACCEPT [0:0]
-A POSTROUTING -o ens3 -j MASQUERADE
# End each table with the 'COMMIT' line or these rules won't be processed
COMMIT
In Nano text editor, you can go to the end of the file by pressing Ctrl W, then pressing Ctrl V.
The above lines will append (-A) a rule to the end of of POSTROUTING chain of nat table. It will link your virtual private network with the Internet. And also hide your network from the outside world. So the Internet can only see your VPN server’s IP, but can’t see your VPN client’s IP, just like your home router hides your private home network.
Save and close the file. Then enable UFW.
sudo ufw enable
If you have enabled UFW before, then you can use systemctl to restart UFW.
sudo systemctl restart ufw
Now if you list the rules in the POSTROUTING chain of the NAT table by using the following command:
sudo iptables -t nat -L POSTROUTING
You can see the Masquerade rule.
Step 6: Install a DNS Resolver on the Server
Since we specified the VPN server as the DNS server for client, we need to run a DNS resolver on the VPN server. We can install the bind9 DNS server.
sudo apt install bind9
Once it’s installed, BIND will automatically start. You can check its status with:
systemctl status bind9
Sample output:
● named.service - BIND Domain Name Server Loaded: loaded (/lib/systemd/system/named.service; enabled; vendor preset: enabled) Active: active (running) since Sun 2020-05-17 08:11:26 UTC; 37s ago Docs: man:named(8) Main PID: 13820 (named) Tasks: 5 (limit: 1074) Memory: 14.3M CGroup: /system.slice/named.service └─13820 /usr/sbin/named -f -u bind
If it’s not running, start it with:
sudo systemctl start bind9
Edit the BIND DNS server’s configuration file.
sudo nano /etc/bind/named.conf.options
Add the following line to allow VPN clients to send recursive DNS queries.
allow-recursion { 127.0.0.1; 10.10.10.0/24; };
Save and close the file. Restart BIND9 for the changes to take effect.
sudo systemctl restart bind9
Then you need to run the following command to allow VPN clients to connect to port 53.
sudo ufw insert 1 allow in from 10.10.10.0/24
Step 7: Open WireGuard Port in Firewall
Run the following command to open UDP port 51820 on the server.
sudo ufw allow 51820/udp
Step 8: Start WireGuard
server
Run the following command on the server to start WireGuard.
sudo wg-quick up /etc/wireguard/wg0.conf
To stop it, run
sudo wg-quick down /etc/wireguard/wg0.conf
You can also use systemd service to start WireGuard.
sudo systemctl start [email protected]
Enable auto-start at system boot time.
sudo systemctl enable [email protected]
Check its status with the following command. Its status should be active (exited).
systemctl status [email protected]
Now WireGuard server is ready to accept client connections.
Client
Start WireGuard.
sudo systemctl start [email protected]
Enable auto-start at system boot time.
sudo systemctl enable [email protected]
Check its status:
systemctl status [email protected]
Now go to this website: http://icanhazip.com/ to check your public IP address. If everything went well, it should display your VPN server’s public IP address instead of your client computer’s public IP address.
Policy Routing
By default, all traffic on the VPN client will be routed through the VPN server. Sometimes you may want to route only a specific type of traffic, based on the transport layer protocol and the destination port. This is known as policy routing.
Policy routing is configured on the client computer, so edit the client configuration file.
sudo nano /etc/wireguard/wg-client0.conf
For example, if you add the following 3 lines in the [interface] section, then WireGuard will create a routing table named “1234” and add the ip rule into the routing table. In this example, traffic will be routed through VPN server only when TCP is used as the transport layer protocol and the destination port is 25, i.e, when the client computer sends emails.
Table = 1234 PostUp = ip rule add ipproto tcp dport 25 table 1234 PreDown = ip rule delete ipproto tcp dport 25 table 1234
Save and close the file. Then restart the WireGuard client.
sudo systemctl restart [email protected]
If WireGuard client fails to restart, then you need to stop it with the following command.
sudo wg-quick down /etc/wireguard/wg-client0.conf
Then start it again.
sudo systemctl start [email protected]
VPN Kill Switch
By default, your computer can access the Internet via the normal gateway when the VPN connection is disrupted. You may want to enable the kill switch feature, which prevents the flow of unencrypted packets through non-WireGuard interfaces.
Edit the client configuration file.
sudo nano /etc/wireguard/wg-client0.conf
Add the following two lines in the [interface] section.
PostUp = iptables -I OUTPUT ! -o %i -m mark ! --mark $(wg show %i fwmark) -m addrtype ! --dst-type LOCAL -j REJECT PreDown = iptables -D OUTPUT ! -o %i -m mark ! --mark $(wg show %i fwmark) -m addrtype ! --dst-type LOCAL -j REJECT
Like this:
[Interface] Address = 10.10.10.2/24 DNS = 10.10.10.1 PrivateKey = cOFA x5UvHF a3xJ6enLatG DoE3I5PhMgKrMKkUyXI= PostUp = iptables -I OUTPUT ! -o %i -m mark ! --mark $(wg show %i fwmark) -m addrtype ! --dst-type LOCAL -j REJECT PreDown = iptables -D OUTPUT ! -o %i -m mark ! --mark $(wg show %i fwmark) -m addrtype ! --dst-type LOCAL -j REJECT [Peer] PublicKey = kQvxOJI5Km4S1c7WXu2UZFpB8mHGuf3Gz8mmgTIF2U0= AllowedIPs = 0.0.0.0/0 Endpoint = 12.34.56.78:51820
Save and close the file. Then restart the WireGuard client.
sudo systemctl restart [email protected]
Wrapping Up
That’s it! I hope this tutorial helped you install and configure WireGuard on Debian. As always, if you found this post useful, then subscribe to our free newsletter to get more tips and tricks 🙂
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