> ## Documentation Index
> Fetch the complete documentation index at: https://mintlify.com/pion/ice/llms.txt
> Use this file to discover all available pages before exploring further.

# Introduction

> A Go implementation of the Interactive Connectivity Establishment (ICE) protocol for WebRTC and P2P applications

## What is Pion ICE?

Pion ICE is a pure Go implementation of the Interactive Connectivity Establishment (ICE) protocol, as defined in [RFC 5245](https://datatracker.ietf.org/doc/html/rfc5245). ICE is a framework used by WebRTC and other peer-to-peer applications to establish network connections between peers, even when they are behind NATs or firewalls.

<Info>
  Pion ICE is part of the larger [Pion WebRTC](https://github.com/pion/webrtc) project, which provides a complete WebRTC implementation in Go.
</Info>

## Why ICE?

Establishing direct peer-to-peer connections over the internet is challenging due to:

* **NAT traversal**: Most devices sit behind Network Address Translation (NAT), making direct connections difficult
* **Firewall restrictions**: Corporate and residential firewalls often block incoming connections
* **Multiple network interfaces**: Devices may have several network paths (WiFi, Ethernet, cellular)
* **Connection reliability**: Networks may change during a session

ICE solves these problems by:

1. Gathering multiple candidate addresses (local, server-reflexive, relay)
2. Exchanging candidates with the remote peer
3. Testing candidate pairs to find working connections
4. Selecting the best path based on priority and latency

## Key Features

Pion ICE provides a complete ICE implementation with:

<CardGroup cols={2}>
  <Card title="Full ICE Support" icon="network-wired">
    Complete implementation of RFC 5245 with support for all candidate types: host, server-reflexive, peer-reflexive, and relay
  </Card>

  <Card title="Multiple Transports" icon="arrows-spin">
    Support for UDP, TCP (passive and active), and multiplexing for efficient port usage
  </Card>

  <Card title="STUN & TURN" icon="server">
    Built-in support for STUN servers (NAT discovery) and TURN servers (relay) with TLS/DTLS encryption
  </Card>

  <Card title="Continual Gathering" icon="refresh">
    Dynamic candidate gathering that responds to network changes during a session
  </Card>

  <Card title="mDNS Support" icon="broadcast-tower">
    Local network discovery using Multicast DNS for privacy-preserving local connections
  </Card>

  <Card title="Lite Mode" icon="feather">
    Lightweight ICE implementation for servers that only provide host candidates
  </Card>
</CardGroup>

## Use Cases

### WebRTC Applications

Pion ICE is the foundation for WebRTC connectivity in Go applications:

* Video conferencing platforms
* Real-time collaboration tools
* Live streaming services
* Browser-to-server communication

### Peer-to-Peer Networking

Build P2P applications without browser constraints:

* Distributed systems and microservices
* File sharing and synchronization
* Gaming backends with direct peer connections
* IoT device communication

### NAT Traversal Solutions

Use ICE for any application requiring NAT traversal:

* VoIP and telephony systems
* Remote desktop and control applications
* Tunneling and proxy services

## Connection States

ICE connections progress through several states:

```go theme={null}
ConnectionStateNew          // Agent is gathering addresses
ConnectionStateChecking     // Testing candidate pairs
ConnectionStateConnected    // Found working pair, still checking others
ConnectionStateCompleted    // Finished checking all pairs
ConnectionStateFailed       // No working connection found
ConnectionStateDisconnected // Lost connection
ConnectionStateClosed       // Agent shut down
```

## Architecture Overview

At the core of Pion ICE is the `Agent` type, which:

* Manages candidate gathering from local interfaces
* Coordinates with STUN/TURN servers
* Performs connectivity checks with remote candidates
* Maintains connection state and handles keepalives
* Provides a `net.Conn` interface for data transfer

## Next Steps

<CardGroup cols={2}>
  <Card title="Installation" icon="download" href="/installation">
    Get started by installing Pion ICE in your Go project
  </Card>

  <Card title="Quickstart" icon="rocket" href="/quickstart">
    Build your first ICE connection with a complete example
  </Card>
</CardGroup>

<Note>
  Pion ICE requires **Go 1.24.0** or later for full compatibility with the latest features.
</Note>