EMnify OpenVPN configuration supports both UDP and TCP. Clients have the possibility to use either one of the protocols by changing the configuration file they download in the EUI. After understanding the pros and cons of both protocols (part I), we'll check how to change the configuration file (part II).

1. UDP vs TCP

1.1 Transmission Control Protocol (TCP)

TCP is also known as the "reliable" protocol because it guarantees delivery. For each packet sent over TCP, a confirmation packet is answered by the destination server. If no such confirmation is received by the source, a new packet will be sent. When using TCP you have a guaranteed delivery of data.

1.2 User Datagram Protocol (UDP)

UDP does not guarantee delivery of data and is therefore not as reliable as TCP. Packets are simply sent without waiting for any acknowledgement of delivery or retries. This enables faster connection but is less reliable.

As a summary we can say that:
• TCP is reliable
• UDP is fast

1.3 Which protocol should you use?

This depends on what you are planning to use our service for. If reliability is your primary concern, TCP would be advised. If you are looking for speed, you should use UDP.

The choice also depends on the application. Here are a few examples:
UDP is generally used for Voice over IP (VoIP), media streaming, online gaming.
TCP is generally used for web (https connections), SSH, IMAP/POP (for email).

More information on this topic can be found here: https://www.bestvpn.com/guides/openvpn-tcp-vs-udp-difference-choose/

2. Changing protocol in the EMnify configuration

As mentionned before, EMnify's OpenVPN configuration supports both protocols and clients can choose the one they want to use. The standard protocol used is UDP. To change the protocol, you first need to download the configuration file in the EUI:

Log in your account and click on the link symbol on the upper right corner called "Tokens, IPs and VPNs setup". Find the category "VPN configuration" and download the configuration that fits with your OS and Regional Internet Breakout.

Once you have downloaded the configuration file, you can edit it with a text editor (I advise you to use Notepad++): open the file ".openvpn" for windows" and ".conf" for Linux and look for "proto udp" (3rd line). Change it to "proto tcp" if you want to switch to TCP.

Linux users also need to change the 7th line from "explicit-exit-notify 3" to ";explicit-exit-notify 3" By adding ";" you disable this function.

Related Issue: OpenVPN proto TCP for Windows OS