OpenVPN Server Setup

Complete guide to setting up an OpenVPN server with certificate-based authentication

🚀 Quick Installation

Use our automated script for fastest setup:

Terminal
curl -O https://raw.githubusercontent.com/angristan/openvpn-install/master/openvpn-install.sh
chmod +x openvpn-install.sh
sudo ./openvpn-install.sh

The script will guide you through the configuration process. For manual setup, continue reading below.

1 System Preparation

Update System & Install Dependencies

Terminal
sudo apt update && sudo apt upgrade -y
sudo apt install openvpn easy-rsa iptables-persistent -y

Enable IP Forwarding

Terminal
echo 'net.ipv4.ip_forward = 1' | sudo tee -a /etc/sysctl.conf
sudo sysctl -p

2 Certificate Authority Setup

Initialize PKI

Terminal
make-cadir ~/openvpn-ca
cd ~/openvpn-ca
source vars
./clean-all
./build-ca

Generate Server Certificate

Terminal
./build-key-server server
./build-dh
openvpn --genkey --secret keys/ta.key

3 Server Configuration

Copy Certificates

Terminal
cd ~/openvpn-ca/keys
sudo cp ca.crt ca.key server.crt server.key ta.key dh2048.pem /etc/openvpn/

Create Server Configuration

Create the OpenVPN server configuration file:

/etc/openvpn/server.conf
port 1194
proto udp
dev tun

ca ca.crt
cert server.crt
key server.key
dh dh2048.pem

server 10.8.0.0 255.255.255.0
ifconfig-pool-persist ipp.txt

push "redirect-gateway def1 bypass-dhcp"
push "dhcp-option DNS 8.8.8.8"
push "dhcp-option DNS 8.8.4.4"

keepalive 10 120
tls-auth ta.key 0
cipher AES-256-CBC
user nobody
group nogroup
persist-key
persist-tun

status openvpn-status.log
log-append /var/log/openvpn.log
verb 3
explicit-exit-notify 1

4 Network Configuration

Configure Firewall Rules

Terminal
sudo iptables -t nat -A POSTROUTING -s 10.8.0.0/24 -o eth0 -j MASQUERADE
sudo iptables -A INPUT -i tun+ -j ACCEPT
sudo iptables -A FORWARD -i tun+ -j ACCEPT
sudo iptables -A FORWARD -i tun+ -o eth0 -m state --state RELATED,ESTABLISHED -j ACCEPT
sudo iptables -A FORWARD -i eth0 -o tun+ -m state --state RELATED,ESTABLISHED -j ACCEPT
sudo netfilter-persistent save

Configure UFW (Alternative)

Terminal
sudo ufw allow 22/tcp
sudo ufw allow 1194/udp
sudo ufw --force enable

5 Start OpenVPN Service

Terminal
sudo systemctl enable openvpn@server
sudo systemctl start openvpn@server
sudo systemctl status openvpn@server

6 Client Configuration

Generate Client Certificate

Terminal
cd ~/openvpn-ca
source vars
./build-key client1

Client Configuration File

Create a client configuration file:

client1.ovpn
client
dev tun
proto udp
remote YOUR_SERVER_IP 1194
resolv-retry infinite
nobind
user nobody
group nogroup
persist-key
persist-tun
ca ca.crt
cert client1.crt
key client1.key
tls-auth ta.key 1
cipher AES-256-CBC
verb 3

🔧 Troubleshooting

Connection Issues

  • • Check if OpenVPN service is running: sudo systemctl status openvpn@server
  • • Verify firewall rules allow OpenVPN traffic on port 1194/udp
  • • Check server logs: sudo tail -f /var/log/openvpn.log

Certificate Issues

  • • Ensure all certificate files have correct permissions
  • • Verify certificate dates haven't expired
  • • Check that client and server certificates are signed by the same CA