Introduction OpenVPN is extremely popular and a full-featured SSL VPN (Virtual Private Network) software. It implements OSI layer 2 or 3 secure network extension using the SSL/TLS protocol. Like much other popular software, it is open-source, free software and distributed under the GNU GPL. A VPN allows you to connect securely to an insecure public network such as wifi network at the airport or hotel. In many enterprises and government offices, VPN is needed to access your corporate server resources. Another widespread usage to bypass the geo-blocked sites/apps and increase your privacy or safety online. This tutorial provides step-by-step instructions for configuring an OpenVPN server on Ubuntu Linux 20.04 LTS server.
Procedure: Ubuntu 20.04 LTS Set Up OpenVPN Server In 5 Minutes
The steps are as follows:
Step 1 – Update your system
First, run the apt command to apply security updates:
sudo apt update
sudo apt upgrade
Step 2 – Find and note down your IP address
Use the ip command as follows:
ip a
ip a show eth0
Alternatively we can run the following dig command/host command to find out our public IP address from Linux command line itself:
dig +short myip.opendns.com @resolver1.opendns.com
## OR ##
dig TXT +short o-o.myaddr.l.google.com @ns1.google.com | awk -F'”‘ ‘{ print $2}’
A note about IP address assigned to your server
Most cloud and bare-metal servers have two types of IP address provided by the ISP:
- Public static IP address directly assigned to your box and routed from the Internet. For example, Linode, Digital Ocean, and others give you direct public IP address.
- Private static IP address directly attached to your server and your server is behind NAT with public IP address. For example, AWS EC2/Lightsail give you this kind of NAT public IP address./li>
The script will automatically detect your networking setup. All you have to do is provide a correct IP address when asked for it.
Step 3 – Download and run openvpn-install.sh script
I am going to use the wget command as follows:
wget https://git.io/vpn -O openvpn-ubuntu-install.sh
Now we downloaded the script and it is time to make it executable. Hence, set up permissions using the chmod command:
chmod -v +x openvpn-ubuntu-install.sh
mode of ‘openvpn-ubuntu-install.sh’ changed from 0644 (rw-r–r–) to 0755 (rwxr-xr-x)
One can view the script using a text editor such as nano/vim:
nano openvpn-ubuntu-install.sh
Run openvpn-ubuntu-install.sh script to install OpenVPN server
Now all you have to do is:
sudo ./openvpn-ubuntu-install.sh
Sample session from AWS/Lightsail where my cloud server is behind NAT:
Sample session from Linode/DO server where cloud server has direct public IPv4 address:
I strongly suggest that you always choose the DNS server option as 1.1.1.1 or Google DNS. Those are fast Geo-distributed DNS servers and reached from anywhere on the Internet. At the end we should see information as follows:
Your client configuration is available at: /root/linuxdesktop.ovpn
If you want to add more clients, just run this script again!
How do I start/stop/restart OpenVPN server on Ubuntu 20.04 LTS?
We need to use the systemctl command as follows:
Stop the OpenVPN server
sudo systemctl stop openvpn@server
Start the OpenVPN server
sudo systemctl start openvpn@server
Restart the OpenVPN server after changing configuration options
sudo systemctl restart openvpn@server
Show status of the OpenVPN server
sudo systemctl status openvpn@server
Step 4 – Connect an OpenVPN server using iOS/Android/Linux/Windows desktop client
On server your will find a client configuration file called /root/linuxdesktop.ovpn. All you have to do is copy this file to your local desktop using the scp command:
scp [email protected]:/root/linuxdesktop.ovpn .
If root is not allowed to log in into the server, try the following scp command:
ssh [email protected] “sudo -S cat /root/linuxdesktop.ovpn” > linuxdesktop.ovpn
Next, provide this file to your OpenVPN client to connect:
Linux Desktop: OpenVPN client configuration
First, install the openvpn client for your desktop using the yum command/dnf command/apt command:
sudo dnf install openvpn
OR
sudo apt install openvpn
Next, copy desktop.ovpn as follows:
sudo cp linuxdesktop.ovpn /etc/openvpn/client.conf
Test connectivity from the CLI:
sudo openvpn –client –config /etc/openvpn/client.conf
Your Linux system will automatically connect when computer restart using openvpn script/service:
sudo systemctl start openvpn@client # <— start client service
Step 5 – Verify/test the connectivity
Simply visit this page to check your IP address and it much change to your VPN server IP address. Next, execute the following commands after connecting to OpenVPN server from your Linux desktop:
ping 10.8.0.1#Ping to the OpenVPN server gateway
ip route#Make sure routing setup working
## the following must return public IP address of OpenVPN server ##
dig TXT +short o-o.myaddr.l.google.com @ns1.google.com
A note about trouble shooting OpenVPN server and client issues
Check OpenVPN serverfor errors:
sudo journalctl –identifier ovpn-server
Is firewall rule setup correctly on your server? Use the cat command to see rules:
cat /etc/systemd/system/openvpn-iptables.service
Config:
[Unit] Before=network.target [Service] Type=oneshot ExecStart=/sbin/iptables -t nat -A POSTROUTING -s 10.8.0.0/24 ! -d 10.8.0.0/24 -j SNAT --to 172.104.177.197 ExecStart=/sbin/iptables -I INPUT -p udp --dport 1194 -j ACCEPT ExecStart=/sbin/iptables -I FORWARD -s 10.8.0.0/24 -j ACCEPT ExecStart=/sbin/iptables -I FORWARD -m state --state RELATED,ESTABLISHED -j ACCEPT ExecStop=/sbin/iptables -t nat -D POSTROUTING -s 10.8.0.0/24 ! -d 10.8.0.0/24 -j SNAT --to 172.104.177.197 ExecStop=/sbin/iptables -D INPUT -p udp --dport 1194 -j ACCEPT ExecStop=/sbin/iptables -D FORWARD -s 10.8.0.0/24 -j ACCEPT ExecStop=/sbin/iptables -D FORWARD -m state --state RELATED,ESTABLISHED -j ACCEPT ExecStart=/sbin/ip6tables -t nat -A POSTROUTING -s fddd:1194:1194:1194::/64 ! -d fddd:1194:1194:1194::/64 -j SNAT --to 2400:8901::f03c:92ff:fe3e:cf92 ExecStart=/sbin/ip6tables -I FORWARD -s fddd:1194:1194:1194::/64 -j ACCEPT ExecStart=/sbin/ip6tables -I FORWARD -m state --state RELATED,ESTABLISHED -j ACCEPT ExecStop=/sbin/ip6tables -t nat -D POSTROUTING -s fddd:1194:1194:1194::/64 ! -d fddd:1194:1194:1194::/64 -j SNAT --to 2400:8901::f03c:92ff:fe3e:cf92 ExecStop=/sbin/ip6tables -D FORWARD -s fddd:1194:1194:1194::/64 -j ACCEPT ExecStop=/sbin/ip6tables -D FORWARD -m state --state RELATED,ESTABLISHED -j ACCEPT RemainAfterExit=yes [Install] WantedBy=multi-user.target
Another option is to run iptables command and sysctl command commands to verify NAT rule setup on your server:
sudo iptables -t nat -L -n -v
sysctl net.ipv4.ip_forward
NAT Firewall OpenVPN Rules Verification
Insert the rules if not inserted using the following command:
sudo systemctl start openvpn-iptables.service
sudo sysctl -w net.ipv4.ip_forward=1
Is OpenVPN server running and port is open? Use the ss command or netstat command and pidof command/ps command:
netstat -tulpn | grep :1194## 1194 is the openvpn server port ##
ss -tulpn | grep :1194## 1194 is the openvpn server port ##
ps aux | grep openvpn## is the openvpn server running? ##
ps -C openvpn## is the openvpn server running? ##
pidof openvpn## find the openvpn server PID ##
If not running, restart the OpenVPN server:
sudo systemctl restart openvpn@server
Look out for errors:
sudo systemctl status openvpn@server
Can the Linux desktop client connect to the OpenVPN server machine? First you need to run a simple test to see if the OpenVPN server port (UDP 1194) accepts connections:
nc -vu 172.104.177.197 1194
Connection to 172.104.177.197 port [udp/openvpn] succeeded!
If not connected it means either a Linux desktop firewall or your router is blocking access to server. Make sure both client and server using same protocol and port, e.g. UDP port 1194.
Conclusion
Congratulations. You successfully set up an OpenVPN server on Ubuntu Linux 20.04 LTS server running in the cloud. See the OpenVPN website here, Ubuntu page here and Github script page here for additional information.
This entry is 11 of 11 in the OpenVPN Tutorial series. Keep reading the rest of the series:
- How To Setup OpenVPN Server In 5 Minutes on Ubuntu Server
- Install Pi-hole with an OpenVPN to block ads
- Update/upgrade Pi-hole with an OpenVPN
- OpenVPN server on Debian 9/8
- Import a OpenVPN .ovpn file with Network Manager
- Ubuntu 18.04 LTS Set Up OpenVPN Server In 5 Minutes
- CentOS 7 Set Up OpenVPN Server In 5 Minutes
- Pi-Hole and Cloudflare DoH config
- Debian 10 Set Up OpenVPN Server In 5 Minutes
- CentOS 8 OpenVPN server in 5 mintues
- Ubuntu 20.04 LTS OpenVPN server in 5 mintues