https://www.cyberciti.biz/faq/howto-setup-openvpn-server-on-ubuntu-linux-14-04-or-16-04-lts

wget https://git.io/vpn -O openvpn-install.sh

sudo chmod +x openvpn-install.sh
sudo bash openvpn-install.sh

Welcome to this OpenVPN road warrior installer!

Which protocol should OpenVPN use?
1) UDP (recommended)
2) TCP
Protocol [1]: 1

What port should OpenVPN listen to?
Port [1194]:

Select a DNS server for the clients:
1) Current system resolvers
2) Google
3) 1.1.1.1
4) OpenDNS
5) Quad9
6) AdGuard
DNS server [1]: 2

Enter a name for the first client:
Name [client]: iphone

OpenVPN installation is ready to begin.
Press any key to continue…