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OpenVPN Setup Guide with Split Tunneling on Ubuntu

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Prerequisites

• Ubuntu 20.04 or later
• Root or sudo access
• OpenVPN server configuration files

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Step 1: Install OpenVPN

sudo apt update
sudo apt install openvpn -y

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Step 2: Place Configuration Files

sudo cp your-config.ovpn /etc/openvpn/client/

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Step 3: Configure Split Tunneling

sudo nano /etc/openvpn/client/your-config.ovpn

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Modify the following settings:

1. Prevent default gateway override:
   route-nopull
   
2. Route only specific traffic through VPN (e.g., a corporate network 10.0.0.0/24):
   route 10.0.0.0 255.255.255.0
   
3. Ensure correct DNS resolution (Optional):
   dhcp-option DNS 8.8.8.8
   dhcp-option DNS 8.8.4.4
   

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Step 4: Start OpenVPN Client

sudo openvpn --config /etc/openvpn/client/your-config.ovpn --daemon

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Step 5: Verify VPN Connection

curl ifconfig.me

ip route

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Step 6: Enable OpenVPN on Boot (Optional)

sudo nano /etc/systemd/system/openvpn-client.service

[Unit]
Description=OpenVPN client
After=network.target

[Service]
ExecStart=/usr/sbin/openvpn --config /etc/openvpn/client/your-config.ovpn --daemon
Restart=always

[Install]
WantedBy=multi-user.target

sudo systemctl enable openvpn-client
sudo systemctl start openvpn-client

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Step 7: Disconnect OpenVPN

sudo systemctl stop openvpn-client

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Troubleshooting

• Check OpenVPN logs for errors:
  journalctl -u openvpn-client --no-pager
  
• Restart OpenVPN service:
  sudo systemctl restart openvpn-client
  
• Verify routing rules:
  ip route show
  

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Conclusion