Online NAT Type Checker

What is NAT?

NAT stands for Network Address Translation and is the conversion of a packet&s source or destination IP address in order to forward the data packets over the network. There are four core types of NAT:

Full Cone NAT: Any external address and port may access an internal resource as long as the internal resource is contacted first
Restricted Cone NAT: An external IP address can connect to an internal resource only if it has previously interacted with it
Port Restricted Cone NAT: Only if an external IP address and port has interacted through that port with the internal resource it has the accessibility on the external address and port
Symmetric NAT: When packets are sent to an external IP address and port, while being replied from the same, different handles will be provided to the external IP address and port. When two different outside users attempt to connect to the same internal address with the same port number, each will receive a different number

The techniques used in the identification of NAT include port availability and the state of the Internet connection to determine which of the four types of NAT is being used in the network

Local network with NAT Server

How does NAT type influence your connection?

NAT also refers to method whereby routers enable many local devices to share a single public IP address when connecting to the internet. This makes it easy to save IP addresses and to increase the security by effectively hiding internal networks& addresses.

NAT does not pose much of a problem on normal web browsing, where one opens a webpage or watches a video; however, it is a challenge on P2P connections. Gaming, video, or micro-conferencing that mostly employ direct device to device connection may be affected by a kind of NAT type:

Full Cone: Few constraints, it is easy to connect to another network
Restricted Cone and Port Restricted Cone: Restricted access but can join the majority of the networks
Symmetric NAT: Very limited, it results in interaction issues with the community particularly in playing games or attending virtual meetings

Namely, your network behind Symmetric NAT can only make connections to computers in other private networks if the latter allows incoming connections as well. However, media data needs to be sent through a public server like relay or TURN server which has the drawback of introducing more delay and lesser connection quality.

Selecting the right NAT is very important for creating fluent experiences when using the Internet, especially for activities that involve establishment of direct P2P connections.

P2P Connection and Web Real-Time Communication

Peer to peer (P2P) is a connection that enables two or more devices to share data through the internet without the help of an intermediary server. This architecture is widely preferred in real time applications such as online games, voice and video conference and file sharing as it is very helpful in reducing delay and allowing true peer to peer communication. But getting them to connect directly is not always easy and virtually impossible if both the devices are connected with NAT routers.

WebRTC or Web Real-Time Communication is an open-source project that aims to provide the methodology for creating channels of real-time P2P communication between browsers and/or apps. It supports direct transfer of audio, video and data in real time so it plays a critical role in such services like video conferencing, online collaboration, peer to peer file transfers.

How WebRTC Sets Up Peer to Peer Connections

To enable direct connections between devices, WebRTC uses a combination of the listed technologies below:

STUN (Session Traversal Utilities for NAT): It can be used to find out the external IP address, through which connection is possible after passing through NAT
ICE (Interactive Connectivity Establishment): Oversees the coordination in acquiring and checking different network links to identify the best proper connection
TURN (Traversal Using Relays around NAT): However, a direct connection between two peers cannot be formed in some cases (for example one peer is behind the Symmetric NAT) so the data are transmitted through the TURN servers

WebRTC aims at direct connections, though the existence of such restrictive NAT types as Symmetric NAT makes P2P communication impossible without a TURN server to act as a relay. This creates some additional burden, but it guarantees that the messaging can go on in any case.

Communication is now an essential part of many modern applications, which requires the use of WebRTC to ensure the use of applications with low latency and reliable security. However, to be able to reach another node, a proper connection configuration raises a possibility to build direct P2P connection, and therefore, achieve better network performance avoiding relay servers as much as possible.

NAT type distribution statistics is calculated for 10'000 users, latest update: 27^th October 2024. Have any questions or suggestions? Reach out to me at e-mail