OpenVPN is an open-source VPN protocol that makes use of virtual private network (VPN) techniques to establish safe site-to-site or point-to-point connections.
What is the OpenVPN protocol?
OpenVPN uses the TLS/SSL protocol for key exchange and can travel through firewalls and network address translators (NATs). It was written by James Yonan and published under the GNU General Public License (GPL).
OpenVPN allows peers to authenticate each other using a username and password, certificates, or a pre-shared secret key. When used in a multi-client server configuration, it allows the server to launch an authentication certificate for every user, using certificate authority and signature. It uses the OpenSSL encryption library as well as TLSv1/SSLv3 protocols and has a number of control and security features.
What OpenVPN ports does NordVPN use?
With NordVPN, you can connect via OpenVPN both over TCP and UDP.
For OpenVPN TCP connections use port 443.
For OpenVPN UDP connections use port 1194.
You can read more about TCP vs UDP here.
How to set up OpenVPN manually with NordVPN
You can set up an OpenVPN connection manually on different devices. Here are the guides for different operating systems: