This tutorial is going to show you how to set up your own WireGuard VPN server on CentOS. 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. TL;DR
This tutorial assumes that the VPN server and VPN client are both running CentOS operating system.
Log into your CentOS server, then run the following commands to install WireGuard.
# CentOS 8
sudo dnf install elrepo-release epel-release -y
sudo dnf install kmod-wireguard wireguard-tools -y
# CentOS 7
sudo yum install epel-release https://www.elrepo.org/elrepo-release-7.el7.elrepo.noarch.rpm
sudo yum install yum-plugin-elrepo
sudo yum install kmod-wireguard wireguard-tools -y
Then use the same commands to install WireGuard on your local CentOS computer (the VPN client).
sudo mkdir -p /etc/wireguard/
cd /etc/wireguard
wg genkey | sudo tee /etc/wireguard/server_private.key | wg pubkey | sudo tee /etc/wireguard/server_public.key
sudo mkdir -p /etc/wireguard/
cd /etc/wireguard
wg genkey | sudo tee /etc/wireguard/client_private.key | wg pubkey | sudo tee /etc/wireguard/client_public.key
sudo vim /etc/wireguard/wg0.conf
Paste in this content:
[Interface]
Address = 10.10.10.1/24
SaveConfig = true
PrivateKey = private-key-of-your-server
ListenPort = 51820
[Peer]
PublicKey = public-key-of-your-client
AllowedIPs = 10.10.10.2/32
Secure the file like so:
sudo chmod 600 /etc/wireguard/ -R
sudo vim /etc/wireguard/wg-client0.conf
Paste in this content:
[Interface]
Address = 10.10.10.2/24
DNS = 10.10.10.1
PrivateKey = private-key-of-your-client
[Peer]
PublicKey = public-key-of-your-server
AllowedIPs = 0.0.0.0/0 # to allow untunneled traffic, use `0.0.0.0/1, 128.0.0.0/1` instead
Endpoint = public-ip-of-your-server:51820
PersistentKeepalive = 25
Secure the config like so:
sudo chmod 600 /etc/wireguard/ -R
sudo vim /etc/sysctl.conf
Add the following line at the end of this file.
net.ipv4.ip_forward = 1
sudo sysctl -p # The -p option will load sysctl settings from /etc/sysctl.conf file. This command will preserve our changes across system reboots.
Run the following command to enable IP masquerading in the server firewall.
sudo firewall-cmd --zone=public --permanent --add-masquerade
sudo systemctl reload firewalld
This will hide your VPN 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.
Since we specify 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 dnf install bind
sudo systemctl start named
sudo systemctl enable named
systemctl status named
Edit the BIND main configuration file /etc/named.conf.
sudo vim /etc/named.conf
In the options clause, you can find the following two lines.
listen-on port 53 { 127.0.0.1; };
listen-on-v6 port 53 { ::1; };
This makes named listen on localhost only. If you want to allow clients in the same network to query domain names, then comment out these two lines. (add double slashes at the beginning of each line)
// listen-on port 53 { 127.0.0.1; };
// listen-on-v6 port 53 { ::1; };
Find the following line.
allow-query { localhost; };
Add the 10.10.10.0/24 network range so that VPN clients can send DNS queries. Note that you need to end each network range with a semicolon.
allow-query { localhost; 10.10.10.0/24; };
Save and close the file. Restart BIND9 for the changes to take effect.
sudo systemctl restart named
Then you need to run the following command to allow VPN clients to connect to port 53.
sudo firewall-cmd --zone=public --permanent --add-rich-rule='rule family="ipv4" source address="10.10.10.0/24" accept'
Run the following command to open UDP port 51820 on the server.
sudo firewall-cmd --permanent --add-port=51820/udp
sudo systemctl reload firewalld
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 wg-quick@wg0.service
If the start failed, you should check the log to find out what’s wrong.
sudo journalctl -eu wg-quick@wg-client0.service
Enable auto-start at system boot time with the following command.
sudo systemctl enable wg-quick@wg0.service
Now WireGuard server is ready to accept client connections.
Start WireGuard.
sudo systemctl start wg-quick@wg-client0.service
Enable auto-start at system boot time.
sudo systemctl enable wg-quick@wg-client0.service
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, and we need to stop the VPN connection first.
sudo systemctl stop wg-quick@wg-client0.service
Then 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 start WireGuard client again.
sudo systemctl start wg-quick@wg-client0.service
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. Stop the WireGuard client process.
sudo systemctl stop wg-quick@wg-client0.service
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 = RaoAdsIEIwgV9DHNSubxWVG+nZ1GP/c3OU6A/efBJ0I=
AllowedIPs = 0.0.0.0/0
Endpoint = 12.34.56.78:51820
PersistentKeepalive = 25
Save and close the file. Then start the WireGuard client.
sudo systemctl start wg-quick@wg-client0.service
That's it. Happy networking!
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