STUN servers help establish peer-to-peer (P2P) network connections over the Internet. STUN stands for Session Traversal Utilities for NAT, and a STUN server is a network service that allows clients to discover their public IP addresses and the NAT (Network Address Translation) type behind them. NAT is a technology that allows multiple devices on a private network to share a single public IP address. NAT is used to connect devices on a private network to the Internet and is implemented in routers, firewalls, and other network devices.
- STUN point-to-point connections
- STUN message types
- STUN binding requests and responses
- STUN NAT types and mapping techniques
- STUN server deployment and configuration
- Best practices for STUN servers
When two devices on the internet want to establish a P2P connection, they need to exchange signaling messages to negotiate the connection. However, NAT can make it difficult for devices to establish P2P connections on the Internet, as NAT-based devices can block incoming connections or change the addresses of incoming packets.
STUN servers are used to help devices establish P2P connections despite NAT. STUN servers provide a service that allows clients to discover their public IP addresses, NAT types, and whether they can receive incoming connections.
STUN point-to-point connections
STUN servers help establish peer-to-peer (P2P) connections by allowing clients to discover their public IP addresses, NAT types, and whether they can receive incoming connections.
To establish a P2P connection, devices must discover their public IP addresses and NAT types and then exchange this information as part of the signaling process. STUN servers provide a service that allows clients to send STUN bind requests, which are special messages asking the STUN server to identify the client's public IP address and NAT type.
When a client sends a STUN bind request to a STUN server, the STUN server responds with a STUN bind response that includes the client's public IP address and NAT type. The client can use this information to determine whether it can receive incoming connections and establish a P2P connection with the other device.
A STUN server is a network service that listens for STUN binding requests received from clients and responds with STUN binding responses. STUN servers usually run on a dedicated machine or virtual machine and are usually connected to the Internet through a high-bandwidth connection.
STUN servers are designed to be simple and lightweight and do not maintain state or context about the clients that connect to them. When a client sends a STUN bind request to a STUN server, the STUN server responds with a STUN bind reply and then forgets about the client. This allows STUN servers to service many clients simultaneously without requiring significant resources.
STUN servers are usually implemented with a simple UDP server that listens for incoming STUN messages on a known port (for example, 3478). When a STUN message is received, the STUN server analyzes the message, processes it and sends a response to the client.
STUN message types
STUN is a simple protocol that uses a message-based format to exchange information between clients and servers. STUN messages are sent over UDP and consist of a fixed-length header followed by zero or more attributes.
There are three types of STUN reports:
- binding order: A bind request is a message sent by a client to a STUN server asking the server to identify the client's public IP address and NAT type. Bind requests are sent by clients that want to establish a peer-to-peer connection and need to discover their public IP addresses and NAT types.
- required answer: A bind response is a message sent by a STUN server to a client in response to a bind request. Bind responses contain the client's public IP address and NAT type and are used by the client to determine whether it can receive incoming connections and establish a peer-to-peer connection with the other device.
- Link error response– A bind error response is a message that a STUN server sends to a client in response to a bind request if an error occurs while processing the request. Connection error responses contain an error code and policy and are used by the client to handle errors that may occur when establishing a peer-to-peer connection.
STUN attributes are used to convey additional information in STUN messages. There are many different types of STUN attributes and they are used for different purposes e.g. B. to identify the client, pass NAT information and support authentication.
STUN binding requests and responses
STUN link requests and responses are used to exchange information between STUN clients and servers to support establishing point-to-point (P2P) connections.
A STUN bind request is a message sent by a client to a STUN server, asking the server to identify the client's public IP address and NAT type. Bind requests are sent by clients who want to establish a P2P connection and need to discover their public IP addresses and NAT types.
Here is an example of a STUN link request:
0 1 2 30 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1+-+-+-+-+-+-+-+ -+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0 0| STUN message type | Message length |+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- + - +-+-+-+-+-+-+-+-+| Magic Cookie |+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - +-+-+-+-+-+-+-+-+| || Transaction ID (96 bits) || |+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ -+-+-+-+-+-+-+-+
A STUN bind response is a message sent by a STUN server to a client in response to a bind request. Bind responses contain the client's public IP address and NAT type and are used by the client to determine whether it can receive incoming connections and establish a P2P connection with the other device.
Here is an example of a STUN binding response:
0 1 2 30 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1+-+-+-+-+-+-+-+ -+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |0 0| STUN message type | Message length |+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+- + - +-+-+-+-+-+-+-+-+| Magic Cookie |+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - +-+-+-+-+-+-+-+-+| || Transaction ID (96 bits) || |+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ -+-+-+-+-+-+-+-+| Assigned Address Family | Assigned port |+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ -+-+-+-+-+-+-+-+-+| Assigned IP address (32 bits) |+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ - +-+-+-+-+-+-+-+-+-+-+-+
STUN NAT types and mapping techniques
STUN servers use NAT information to help clients establish peer-to-peer (P2P) connections. NAT type refers to the way a NAT-based device (eg router, firewall) processes incoming connections and assigns them to internal devices on a private network.
There are several different types of NAT, and each type of NAT has its own characteristics and behaviors that can affect the ability of devices on the Internet to establish P2P connections. STUN servers use NAT information to help clients determine whether they can receive incoming connections and establish P2P connections with other devices.
Here are some common NAT types and their characteristics:
- wet full cone: A Full Cone NAT is a NAT that allows any external device to establish an inbound connection with an internal device if the internal device has previously sent a packet to the external device. Full-cone NATs are the most permissive NAT type and the easiest P2P connections to establish.
- NAT restricted icon: A narrow cone NAT is a NAT that allows any external device to establish an inbound connection with an internal device if the internal device has previously sent a packet to the external device and the external device's IP address and port match the address IP and port of the internal device. Harbor. Narrow cone NATs are less permissive than full cone NATs and may require additional techniques to establish P2P connections.
- Port Restricted Cone NAT: A strict port cone NAT is a NAT that allows any external device to establish an inbound connection with an internal device if the internal device has previously sent a packet to the external device and has the IP address and port of the external device corresponding IP address and port of the internal device and the port of the external device is within a certain range. Port constrained cone NATs are even less permissive than constrained cone NATs and may require additional techniques to establish P2P connections.
- NAT symmetry: A symmetric NAT is a NAT that assigns each internal device a different external IP address and port for each outgoing connection. Symmetric NATs are the most restrictive type of NAT and the most difficult to configure on P2P connections.
To establish P2P connections via NAT, STUN servers and clients can use NAT mapping techniques to determine the NAT type, IP address and port mapping used by the NAT. NAT mapping techniques include:
- port prediction: Port prediction is a technique used by clients to guess the port mapping used by a NAT. Clients can send multiple binding requests to a STUN server with different port values and see which port values are assigned by NAT.
- make a hole: Punching is a technique used by clients to establish P2P connections over NAT by sending signaling messages directly to each other. Clients send signaling messages to the STUN server and the STUN server transmits the messages to the other client. The clients then use the NAT mapping information provided by the STUN server to establish a direct connection between them.
STUN server deployment and configuration
STUN servers are typically deployed on dedicated machines or virtual machines and are connected to the Internet through a high-bandwidth connection. STUN servers are designed to be simple, lightweight and do not require significant resources to operate.
To implement a STUN server, you must install the STUN server software and configure it with the desired settings. Most STUN server software is available as an open source project and can be downloaded and compiled from source code. Some popular STUN server software options include:
Stiefel:coturn is a free and open source STUN server that is widely deployed and has a large user base. coturn supports multiple authentication methods and is highly configurable.
Returns:reTurn is a free and open source STUN server that is lightweight and easy to use. reTurn supports multiple authentication methods and is highly configurable.
rfc5766-turn-server: rfc5766-turn-server is a free and open source STUN server based on the STUN and TURN protocols defined in RFC 5389 and 5766. rfc5766-turn-server is highly configurable and supports multiple authentication methods.
After installing and configuring your STUN server, you need to open the necessary ports on your firewall to allow incoming STUN traffic. STUN servers usually listen on UDP port 3478, but additional ports may need to be opened if using TURN or other protocols.
Best practices for STUN servers
- Use a secure Signaling Server: STUN servers do not provide any security measures and rely on Signaling Server security to protect against malicious attacks. It is important to use a secure signaling server to protect against attacks such as spoofing, tampering, and replay attacks.
- Use Authentication - STUN servers can support multiple authentication methods to verify the identity of clients and prevent unauthorized access. It's a good idea to use authentication to protect your STUN server from unauthorized use.
- Use encryption: STUN servers do not provide encryption for signaling messages and it is important to use encryption to protect against eavesdropping. It's a good idea to use encryption for message signaling to protect your customers' privacy.
- Use a load balancer: STUN servers can handle a large number of clients simultaneously, but it's a good idea to use a load balancer to spread the load across multiple STUN servers to improve availability.
- Monitoring and Logging: It is important to monitor and log activity on your STUN server to identify and troubleshoot problems and ensure that your STUN server is operating optimally.
The STUN server allows clients to find out their public address, the type of NAT they are behind and the Internet side port associated by the NAT with a particular local port. This information is used to set up UDP communication between the client and the VoIP provider to establish a call.How do STUN and TURN servers work? ›
A TURN (Traversal Using Relays around NAT) server goes around the network address, essentially traversing the connection using relays. So when a STUN server cannot establish a connection between the two parties, the TURN server steps in as an intermediary.What is the difference between STUN server and TURN server? ›
STUN server is used to let peers know each other's external address to start the peer-to-peer streams transmission behind the NAT. TURN server is used to let peers transmit streams to each other behind a firewall. There is no peer-to-peer streams transmission in this case. All media traffic goes through a TURN server.How do I connect to a STUN server? ›
- To Configure the STUN Server Settings:
- On the Management Portal menu window, click System Configuration > Host. The Configuration page opens.
- Click the STUN Server tab.
- Enter your Host and Port settings.
- Click Update and Commit Changes buttons to enact your changes.
STUN (Session Traversal Utilities for NAT)
This is needed for them to connect directly. A peer does not know its public IP address since that is handled by NAT and is beyond the knowledge of the peer. This is where the STUN server comes into the picture.
Yes stun server are completely secure and the connections are encrypted. STUN servers are used to show the client that is behind a NAT or Multiple NATs what its own public IP and port number is, so that peer to peer connection is made possible.How do STUN devices work? ›
Stun guns send an electrical charge into the attacker's body in order to stun and cause extreme discomfort. This electric pulse temporarily disrupts muscle functions and stuns the attacker for a few moments, giving you enough time to escape or take other necessary self-defense steps.Is Google STUN server free? ›
The Google STUN server is something you can freely use for development purposes, but, as a free service, there is no SLA.How do you implement STUN? ›
- Step 1: Firewall rules to Open ports: ...
- Step 2: Coturn installation. ...
- Step 3: Start the Coturn Daemon at Startup. ...
- Step 4: Create a TURN user to Next, edit the main configuration file. ...
- Step 5: Restart the Coturn Service. ...
- Step 6: Testing Time.
TURN is preferred because it is capable to traverse symmetric NATs too. However, STUN is useful to speedup the connection out of getting immediate candidates when users are sitting behind same NAT e.g. LAN.
- A STUN server works if you can gather a candidate with type "srflx" .
- A TURN server works if you can gather a candidate with type "relay" .
UDP/TCP/TLS: Typically, STUN uses UDP, TCP or TLS as its transport protocol. The well known UDP/TCP port for STUN traffic is 3478.Are there public STUN servers? ›
A STUN server operates on the public network and responds to the common question – 'What is my IP address? ' Using the STUN server, clients can access information about their public address and the type of NAT running on the gateway.What credentials do I need for Google STUN server? ›
STUN servers do not require credentials, you should be able to use stun.l.google.com:19302.What does STUN mean in Internet? ›
STUN (Session Traversal Utilities for NAT) is an auxiliary protocol for transmitting data around a NAT (Network Address Translator). STUN returns the IP address, port, and connectivity status of a networked computer behind a NAT.Is STUN TCP or UDP? ›
STUN uses UDP, and STUN servers typically listen for UDP requests on port 3478. For a client to use STUN, their network must allow UDP traffic.What is STUN on my router? ›
STUN is a mechanism for providing an endpoint (softphone, IP-Phone, etc.) a way to determine the IP address and port allocated by a NAT that corresponds to its private IP address and port. It also helps an endpoint keep a NAT binding alive and even perform connectivity checks between two endpoints.What is the port range for STUN? ›
The STUN server uses a single port for client connections (3478 by default), so this port should be opened up for the public in the server's network configuration or Security Group. If using TURN relay, then the whole range of TURN ports (49152 to 65535 by default) should be opened up too, besides the client port.What is the most secure server? ›
- DreamHost – website security for personal sites.
- Hostinger – very affordable and secure web hosting solution.
- A2 Hosting – security against most malicious threats.
- SiteGround – overall the best secure web hosting provider.
- InterServer – no-nonsense secure web hosting.
WhatsApp is a popular messaging and voice over IP (VoIP) service owned by Facebook. The WhatsApp STUN protcol detects messages and notifications.
STUN connectivity check messages are used to find which caller/called party media paths work, and the best working path is selected. Media (that is, RTP/RTCP packets secured using SRTP) are then sent using the selected candidate pair. The Transport relay is deployed as part of Microsoft 365 and Office 365.What is an electronic stun device? ›
What is a Taser? A Taser* is a hand-held, electro-muscular disruption device that is capable of incapacitating a person and causing pain through the application of an electrical current. For example, Tasers could be used by police to temporarily incapacitate a violent or combative person during arrest.How far away does a stun gun work? ›
It is sold by Axon, formerly TASER International. It fires two small barbed darts intended to puncture the skin and remain attached to the target, at 55 m/s (120 mph; 200 km/h). Their range extends from 4.5 m (15 ft) for non-Law Enforcement Tasers to 10.5 m (34 ft) for Law Enforcement Tasers.How long does a stun gun disable someone? ›
They are activated by pulling a trigger, which releases electricity between two metal prongs at the end of the device. Stun guns deliver a painful shock when electrified prongs touch the target. They can stun and briefly incapacitate a person for up to five seconds.What is a VoIP STUN server? ›
A STUN (Session Traversal of User Datagram Protocol [UDP] Through Network Address Translators [NATs]) server allows NAT clients (i.e. IP phones behind a firewall) to setup phone calls to a VoIP provider hosted outside of the local network.How do I TURN off STUN? ›
open Settings -> Preferences -> Advanced -> Network sub-tab -> STUN options and use the drop-down menu to disable STUN.Does Google have physical servers? ›
We own and operate data centers around the world to keep our products running 24 hours a day, 7 days a week.How do I make my own STUN server? ›
- Update the apt-get libraries. sudo apt-get update.
- install coturn. sudo apt-get install coturn.
- Configure the server. Make a backup of the original configuration file ( sudo cp /etc/turnserver. conf /etc/turnserver. conf. ...
- Start the server.
For most WebRTC applications to function a server is required for relaying the traffic between peers, since a direct socket is often not possible between the clients (unless they reside on the same local network).How do I create a STUN server in AWS? ›
- Connect to your Ubuntu server with ssh.
- Add the Universe repository: sudo apt-add-repository universe.
- Update and upgrade Ubuntu: sudo apt update && sudo apt upgrade.
- Reboot the server from the EC2 dashboard or with sudo reboot.
- Install CoTURN server: sudo apt-get install coturn.
Stun is a common status effect that can prevent affected characters from taking most actions, including the ability to block or tag; it is perhaps the deadliest effect in the game when fully exploited, as it leaves the affected character vulnerable to the full damage of ALL forms of attacks, such as hits with critical ...What is a ICE server? ›
Interactive Connectivity Establishment (ICE) is a technique used in computer networking to find ways for two computers to talk to each other as directly as possible in peer-to-peer networking.What is STUN data usage? ›
(Session Traversal Utilities for NAT) An IETF protocol for real-time voice, video and messaging in an IP network. STUN provides the mechanism to communicate with users behind a network address translation (NAT) firewall, which keeps their IP addresses private within the local network (LAN).How do you check if a server is up and running? ›
- Connect to your cloud server on the command line.
- Type systeminfo and press Enter.
- Look for the line that starts with Statistics since , which indicates the date and time when the uptime started.
- Ping command is a network tool used to determine whether a certain IP address or host is accessible.
- Ping works by sending a packet to a specified address and waiting for a reply.
- Ping is also used in checking if the computers on a local network are active.
- On Windows, open Command Prompt. (Mac OS X and Linux users can open Terminal.)
- Type the following command, including your server's IP address: ping -t 0.0. 0.0.
STUN makes sure that the SIP device connecting through a NAT discovers its public IP and also determines which type of NAT is running on its connected gateway. The STUN protocol also enables SIP devices to discover which port external SIP devices can establish a connection with.What is STUN header size? ›
All STUN messages MUST start with a 20-byte header followed by zero or more Attributes. The STUN header contains a STUN message type, magic cookie, transaction ID, and message length. This can be used to differentiate STUN packets from other protocols when STUN is multiplexed with other protocols on the same port.Can TCP be spoofed? ›
IP spoofing is a method in which TCP/IP or UDP/IP data packets are sent with a fake sender address. The attacker uses the address of an authorized, trustworthy system. In this way, it can inject its own packets into the foreign system that would otherwise be blocked by a filter system.What is the role of STUN server in WebRTC? ›
Session Traversal Utilities for NAT (STUN) is a protocol to discover your public address and determine any restrictions in your router that would prevent a direct connection with a peer.
STUN is a network protocol used to retrieve the public IP address (or Transport address) of a device behind NAT so that the device can communicate after knowing its address on the internet. Usually, a STUN server is requested by the peer to know its public IP addresses (or specifically its transport address).How do I know if my STUN server is working? ›
- A STUN server works if you can gather a candidate with type "srflx" .
- A TURN server works if you can gather a candidate with type "relay" .
Stuns do not last for very long, ranging from less than a second, to up to 5 seconds. Therefore, a stun must: Force the enemy to cancel their current ability, or some ultimate abilities.What is stun damage? ›
Stun damage is non-lethal damage. A PC who takes stun damage is defying danger to do anything at all, the danger being “you're stunned.” This lasts as long as makes sense in the fiction—you're stunned until you can get a chance to clear your head or fix whatever stunned you.Is stun a status effect? ›
Stun is a harmful status effect that staggers the player into inaction until it wears off or is removed. Afflicted characters will be unable to act for the short duration, and any spell or ability being cast as the stun takes effect is interrupted.Why should I disable WebRTC? ›
In most web browsers, Web Real-Time Communication (WebRTC) leaks can cause your IP address to be visible, even when you are connected to Avast SecureLine VPN. You can prevent WebRTC leaks by blocking or disabling WebRTC.Is it good to disable WebRTC? ›
Prevent WebRTC Leaks to Stay Safe
If you want to protect your online privacy, you should probably consider disabling WebRTC in your browser. And if you're using a VPN, make sure it does a good job protecting you from different types of leaks.