The protocols known as TURN (Traversal Using Relays around NAT) and STUN (Session Traversal Utilities for NAT) are made to make it easier for peers to communicate with one another across the internet. Giving devices on a private network an address accessed over the internet is done via NAT (Network Address Translation). Peer-to-peer (P2P) connectivity hinders the NAT, which poses a difficulty to direct device communication. TURN and STUN can assist you in getting beyond these barriers.

STUN: Through STUN, clients may discover what kind of NAT they are behind and their public addresses. With the use of this data, P2P networking with other STUN-capable devices is made possible.

TURN: When STUN is insufficient, TURN is utilized. Data is relayed between peers via TURN servers if a direct P2P connection. Despite being less effective than a direct link, this makes sure that even in the most constrained networks, communication is achievable.

Let's understand it better with the help of a example here below:

STUN Servers: Finding Your Way

Imagine you’re in a maze, trying to find the quickest path to your friend. STUN servers act like a map. When you want to connect with someone online, your device asks the STUN server for directions. It helps your device figure out its public address (like your home address), so it can tell other devices where to find you. This helps to decide if you can talk directly to your friend or if you need help from another server.

TURN Servers: The Helpful Middleman

Sometimes, even with the map, you hit a dead end. That’s where TURN server step in. They’re like a helpful friend who knows all the secret passages. When direct communication between you and your friend is blocked by something like a firewall, TURN servers come to the rescue. Your device sends its messages to the TURN server, which then passes them along to your friend. It’s like sending a letter through a friend when you can’t deliver it yourself.