NAT Traversal Protocols
========================

This section covers the core components that enable WebRTC (Web Real-Time Communication) to establish peer-to-peer connectivity, particularly across NAT/firewall environments.

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   ICE
   STUN_SERVER
   TURN_SERVER
   WebRTC

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   * - Component
     - Description
     - Use Case
   * - ICE (Interactive Connectivity Establishment)
     - Framework that tries multiple methods to connect peers.  
       *Combines STUN and TURN for NAT traversal.*
     - Establishing peer-to-peer connections.
   * - STUN (Session Traversal Utilities for NAT)
     - Helps clients discover their public IP and NAT type.  
       *Enables direct peer-to-peer communication.*
     - Enables connections behind NAT/firewalls.
   * - TURN (Traversal Using Relays around NAT)
     - Relays media when direct connection fails.  
       *Acts as a media proxy server.*
     - Ensures reliable communication fallback.
   * - WebRTC (Web Real-Time Communication)
     - A set of APIs and underlying protocols enabling peer-to-peer audio, video, and data in browsers.
       *Enables real-time communication with NAT traversal support via ICE, STUN, and TURN.*
     - Browser-based peer-to-peer media/data connections


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   .. tab-item:: ICE (Interactive Connectivity Establishment)

      **RFC:** RFC 8445

      **Main Features:**

      - Connectivity framework for NAT/firewall traversal
      - Uses STUN and TURN as fallback mechanisms
      - Collects multiple candidates (IP addresses and ports)

      **Use Cases:**

      - Peer-to-peer connection setup in WebRTC
      - Negotiating the best path between peers

      **Alternative Protocols:**

      - None – ICE is the standard coordination mechanism for WebRTC

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         **Let us learn more about ICE:**

         * :ref:`Learnings in this section <ICE_step1>`

         * :ref:`Terminology <ICE_step2>`

         * :ref:`Version Info <ICE_step3>`

         * :ref:`ICE Version&RFC Details <ICE_step5>`

         * :ref:`ICE Basic Setup on Ubuntu using IPv4 <ICE_step19>`

         * :ref:`ICE Basic Setup on Ubuntu using IPv6 <ICE_step20>`

         * :ref:`ICE Protocol Packet Details <ICE_step6>`

         * :ref:`ICE Usecases <ICE_step7>`

         * :ref:`ICE Basic Features <ICE_step8>`

         * :ref:`ICE Feature : Candidate Gathering <ICE_step9>` 

         * :ref:`ICE Feature : Candidate Prioritization <ICE_step10>`

         * :ref:`ICE Feature : Candidate Pairing <ICE_step11>`  

         * :ref:`ICE Feature : Connectivity Checks <ICE_step12>`  

         * :ref:`ICE Feature : Nomination <ICE_step13>`

         * :ref:`ICE Feature : NAT Traversal <ICE_step14>`

         * :ref:`ICE Feature : STUN Integration <ICE_step15>`   

         * :ref:`ICE Feature : TURN Integration <ICE_step16>` 

         * :ref:`ICE Feature : Consent Freshness <ICE_step17>` 

         * :ref:`ICE Feature : Trickle ICE Support <ICE_step18>`

         * :ref:`Reference links <ICE_step21>`

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   .. tab-item:: STUN (Session Traversal Utilities for NAT)

      **RFC:** RFC 5389

      **Main Features:**

      - Discovers public IP addresses of clients
      - Identifies NAT type and firewall behavior
      - Lightweight UDP-based protocol

      **Use Cases:**

      - Peer discovery in WebRTC
      - Assisting direct P2P media path setup

      **Alternative Protocols:**

      - TURN – Used when STUN fails

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         **Let us learn more about STUN:**

         * :ref:`Learnings in this section <STUN_SERVER_step1>`

         * :ref:`Terminology <STUN_SERVER_step2>`

         * :ref:`Version Info <STUN_SERVER_step3>`

         * :ref:`STUN_SERVER Version&RFC Details <STUN_SERVER_step5>`

         * :ref:`STUN_SERVER Basic Setup on Ubuntu using IPv4 <STUN_SERVER_step16>`

         * :ref:`STUN_SERVER Basic Setup on Ubuntu using IPv6 <STUN_SERVER_step17>`

         * :ref:`STUN_SERVER Protocol Packet Details <STUN_SERVER_step6>`

         * :ref:`STUN_SERVER Usecases <STUN_SERVER_step7>`

         * :ref:`STUN_SERVER Basic Features <STUN_SERVER_step8>`

         * :ref:`STUN_SERVER Feature : Public IP Discovery <STUN_SERVER_step9>` 

         * :ref:`STUN_SERVER Feature : NAT Type Detection <STUN_SERVER_step10>`

         * :ref:`STUN_SERVER Feature : Port Mapping Discovery <STUN_SERVER_step11>`  

         * :ref:`STUN_SERVER Feature : Lightweight Protocol <STUN_SERVER_step12>`  

         * :ref:`STUN_SERVER Feature : Client-Server Architecture <STUN_SERVER_step13>`

         * :ref:`STUN_SERVER Feature : Support for IPv4 and IPv6 <STUN_SERVER_step14>`

         * :ref:`STUN_SERVER Feature : Used in WebRTC and VoIP <STUN_SERVER_step15>`   

         * :ref:`Reference links <STUN_SERVER_step18>`

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   .. tab-item:: TURN (Traversal Using Relays around NAT)

      **RFC:** RFC 8656

      **Main Features:**

      - Relays media through an intermediate server
      - Used when direct peer connection is not possible
      - Supports TCP and UDP relaying

      **Use Cases:**

      - WebRTC calls behind symmetric NAT or strict firewalls
      - Reliable fallback for P2P media delivery

      **Alternative Protocols:**

      - STUN – Preferred when NAT allows direct access

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         **Let us learn more about TURN:**

         * :ref:`Learnings in this section <TURN_SERVER_step1>`

         * :ref:`Terminology <TURN_SERVER_step2>`

         * :ref:`Version Info <TURN_SERVER_step3>`

         * :ref:`TURN_SERVER Version&RFC Details <TURN_SERVER_step5>`

         * :ref:`TURN_SERVER Basic Setup on Ubuntu using IPv4 <TURN_SERVER_step19>`

         * :ref:`TURN_SERVER Basic Setup on Ubuntu using IPv6 <TURN_SERVER_step20>`

         * :ref:`TURN_SERVER Protocol Packet Details <TURN_SERVER_step6>`

         * :ref:`TURN_SERVER Usecases <TURN_SERVER_step7>`

         * :ref:`TURN_SERVER Basic Features <TURN_SERVER_step8>`

         * :ref:`TURN_SERVER Feature : NAT Traversal <TURN_SERVER_step9>` 

         * :ref:`TURN_SERVER Feature : Relay Allocation <TURN_SERVER_step10>`

         * :ref:`TURN_SERVER Feature : Transport Protocol Support <TURN_SERVER_step11>`  

         * :ref:`TURN_SERVER Feature : Authentication <TURN_SERVER_step12>`  

         * :ref:`TURN_SERVER Feature : Permission Management <TURN_SERVER_step13>`

         * :ref:`TURN_SERVER Feature : Channel Binding <TURN_SERVER_step14>`

         * :ref:`TURN_SERVER Feature : IPv4 and IPv6 Support <TURN_SERVER_step15>`   

         * :ref:`TURN_SERVER Feature : ICE Integration <TURN_SERVER_step16>` 

         * :ref:`TURN_SERVER Feature : Secure Media Relay <TURN_SERVER_step17>` 

         * :ref:`TURN_SERVER Feature : Resource Management <TURN_SERVER_step18>`

         * :ref:`Reference links <TURN_SERVER_step21>`


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   .. tab-item:: WebRTC (Web Real-Time Communication)

      **Standard:** W3C Recommendation (latest March 13, 2025)  
      **Components:** ICE (RFC 8445), STUN (RFC 5389), TURN (RFC 8656), and Media/Data APIs  
      **Status:** Defines APIs (e.g., RTCPeerConnection) and underlying NAT traversal mechanisms :contentReference[oaicite:0]{index=0}

      **Main Features:**

      - Browser-based framework for real-time peer-to-peer audio, video, and data
      - Integrates ICE, STUN, and TURN for NAT/firewall traversal :contentReference[oaicite:1]{index=1}
      - Exposes APIs (such as `RTCPeerConnection`) to manage connection setup and media handling
      - Supports media handling, secure transport (DTLS/SRTP), and data channels

      **Use Cases:**

      - Video conferencing, voice calls, and real-time messaging in browsers
      - Peer-to-peer file sharing and data exchange via WebRTC Data Channels
      - Any app needing real-time, low-latency, NAT-traversing communication directly between clients

      **Alternative Protocols/Frameworks:**

      - SIP/WebRTC Gateway – for interoperability with legacy VoIP
      - Traditional real-time transport using centralized servers (e.g. WebSockets, media servers)
      - Custom media/data transport over VPN or proprietary mechanisms

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         :card: What You Will Learn in This Section

         **Let us learn more about WebRTC:**

         * :ref:`Learnings in this section <WebRTC_step1>`

         * :ref:`Terminology <WebRTC_step2>`

         * :ref:`Version Info <WebRTC_step3>`

         * :ref:`WebRTC Version&IEEE Details <WebRTC_step5>`

         * :ref:`WebRTC Basic Setup on Ubuntu using IPv4 <WebRTC_step18>`

         * :ref:`WebRTC Basic Setup on Ubuntu using IPv6 <WebRTC_step19>`

         * :ref:`WebRTC Protocol Packet Details <WebRTC_step6>`

         * :ref:`WebRTC Usecases <WebRTC_step7>`

         * :ref:`WebRTC Basic Features <WebRTC_step8>`

         * :ref:`Reference links <WebRTC_step17>`


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