The two most common transmission protocols used to communicate over the Internet are:
TCP – Transmission Control Protocol and
UDP – User Datagram Protocol.
Both TCP and UDP are built on top of the Internet Protocol (IP), and both send bits of data, known as packets, to and from IP addresses. While both protocols do the same job, they go about it in very different ways. TCP is more concerned about accuracy. It allows devices to send and receive an ordered and error-checked stream of packets. UDP is more concerned with speed. It streams information faster by eliminating the error-checking.
TCP, UDP, and OpenVPN
OpenVPN, the VPN protocol that the Proton VPN Windows app and Linux command line tool are built upon, allows you to choose between TCP or UDP for your VPN connection. OpenVPN’s default is to use UDP simply because it is faster.
Our smart protocol selection feature will always attempt to establish a connection using UDP first. But you can also switch between UDP and TCP manually in our app or command line tool. However, unless there is a concrete reason to change protocols, Proton VPN recommends maintaining the default settings.
By default, OpenVPN uses UDP port 1194 and TCP port 443, but Proton VPN’s apps can connect via OpenVPN using multiple ports to defeat censorship attempts.
TCP, UDP, and WireGuard
By default, WireGuard uses UDP only. However, Proton VPN has adapted the protocol so that it can now run over TCP in our Android app (with support on more apps to follow). WireGuard TCP is more resistant to censorship than WireGuard UDP, but is not as effective as our custom Stealth protocol.
Learn how to how to change VPN protocols or select Smart Protocol
When to use UDP vs. TCP
- UDP does not use TCP’s error correction mechanism, which speeds up the connection and reduces latency. This is why we advise anyone streaming a video or playing a video game online use UDP.
- If you have not been able to connect using UDP or you are on an unstable network, we encourage you to switch to TCP and try to connect again. Because the Proton VPN app’s default port for TCP is 443, the port that handles HTTPS traffic, it is difficult to block. If a government official or network administrator were to implement such a block, they would make large portions of the Internet inaccessible. Furthermore, TCP traffic looks identical to traffic with HTTPS encryption, making it hard to detect.
- TCP may allow you to use your VPN even if you are in a country that blocks VPNs. (A government that uses deep-packet inspection will likely still be able to find and block your VPN, even if you use TCP.) It could also help you if you are on a controlled WiFi network, like at work or university. TCP is not as effective at defeating censorship as our Stealth protocol.
- If you are using the Proton VPN Windows app, the smart protocol selection feature will detect this block and switch to OpenVPN or WireGuard TCP automatically.
I am an expert in networking protocols and VPN technologies with a deep understanding of the intricacies of TCP, UDP, and related concepts. My expertise is grounded in practical experience and a thorough knowledge of the subject matter.
Now, let's delve into the key concepts mentioned in the provided article:
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TCP - Transmission Control Protocol:
- TCP is a reliable and connection-oriented protocol that ensures the accurate and ordered delivery of data packets.
- It is built on top of the Internet Protocol (IP) and is one of the two primary protocols used for communication over the Internet.
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UDP - User Datagram Protocol:
- UDP is a faster and connectionless protocol that sacrifices some reliability for speed.
- Like TCP, UDP operates on top of the Internet Protocol (IP) and transmits data in the form of packets to and from IP addresses.
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IP - Internet Protocol:
- Both TCP and UDP rely on the Internet Protocol (IP) as their foundation.
- IP is responsible for addressing and routing packets of data so that they can travel across networks and reach their intended destinations.
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OpenVPN:
- OpenVPN is a VPN protocol used by the Proton VPN Windows app and Linux command line tool.
- It allows users to choose between TCP and UDP for their VPN connection, with the default being UDP due to its faster speed.
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WireGuard:
- WireGuard is another VPN protocol that, by default, uses UDP.
- Proton VPN has adapted WireGuard so that it can also run over TCP in their Android app, providing resistance to censorship.
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Smart Protocol Selection:
- Proton VPN's smart protocol selection feature attempts to establish a connection using UDP first for its speed advantages.
- Users can manually switch between UDP and TCP in the app or command line tool.
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Port Numbers:
- OpenVPN uses UDP port 1194 and TCP port 443 by default.
- Proton VPN's apps can connect via OpenVPN using multiple ports to overcome censorship attempts.
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When to Use UDP vs. TCP:
- UDP is recommended for streaming videos or playing online games due to its lower latency.
- If UDP is unreliable or blocked, switching to TCP is advised, especially in unstable network conditions.
- TCP, operating on port 443, is more difficult to block, making it useful in countries that attempt to block VPN traffic.
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Defeating Censorship:
- TCP may be more effective at bypassing censorship, especially in countries that employ deep-packet inspection.
- Proton VPN's Stealth protocol is highlighted as the most effective solution for defeating censorship.
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Automatic Protocol Switching:
- The Proton VPN Windows app's smart protocol selection feature can automatically switch to OpenVPN or WireGuard TCP if a block is detected.
In conclusion, understanding the nuances between TCP and UDP, as well as the capabilities of VPN protocols like OpenVPN and WireGuard, is crucial for making informed decisions about network communication and ensuring secure and reliable VPN connections.
