I2P Network

Overview

I2P (Invisible Internet Project) is an anonymous network layer that allows for censorship-resistant, peer-to-peer communication. It uses a packet-based protocol and "garlic routing" to provide anonymity for both senders and receivers of messages.

Key Differences from Tor

Packet-based: Uses packets instead of circuits
Garlic Routing: Bundles multiple encrypted messages
Internal Focus: Optimized for internal services (eepsites)
Fully Distributed: No central directory servers
Unidirectional Tunnels: Separate tunnels for in/out traffic

Garlic Routing

Garlic routing is an extension of onion routing that bundles multiple messages together into a single encrypted "clove." This provides additional protection against traffic analysis.

How It Works

1

Message Bundling

Multiple messages are combined into a garlic clove, making it impossible for observers to count individual messages.

2

ElGamal/AES Encryption

Each layer uses ElGamal for key exchange and AES for symmetric encryption, providing strong cryptographic protection.

3

Unidirectional Tunnels

I2P uses separate tunnels for inbound and outbound traffic, improving anonymity against certain attacks.

Network Architecture

Network Database (NetDB)

I2P uses a distributed hash table (DHT) called the Network Database to store router information and lease sets for destinations.

Tunnels

All traffic in I2P flows through tunnels:

Inbound Tunnels: Receive messages from the network
Outbound Tunnels: Send messages to the network
Exploratory Tunnels: Used for NetDB queries

i2p-tunnel-structure

# I2P Tunnel Path Example

Client → Outbound Tunnel [3 hops] → Destination's Inbound Tunnel [3 hops] → Server

# Response travels back via separate tunnels

Server → Server's Outbound → Client's Inbound → Client

Eepsites

Eepsites are websites hosted within the I2P network, accessible only through I2P. They use .i2p pseudo-domains and provide both anonymity for visitors and operators.

Features

Anonymous hosting and visiting
No IP address exposure
Censorship-resistant
End-to-end encrypted connections
Distributed address resolution

Getting Started

i2p-installation

# Add I2P repository (Debian/Ubuntu)

user@cosmic:~$ sudo apt-add-repository ppa:i2p-maintainers/i2p

user@cosmic:~$ sudo apt-get update && sudo apt-get install i2p

# Start I2P router

user@cosmic:~$ i2prouter start

# Access router console at http://127.0.0.1:7657

ℹ️

Integration Time: I2P requires time to integrate with the network. Allow 10-30 minutes for the router to find peers and build tunnels before expecting good performance.

Built-in Applications

I2P-Bote

Decentralized email system

Email

I2PSnark

Anonymous BitTorrent client

File Sharing

IRC

Anonymous IRC servers

Chat

Eepsite Hosting

Host anonymous websites

Web

I2P vs Tor

Feature	I2P	Tor
Routing	Garlic (packet)	Onion (circuit)
Primary Use	Internal services	Anonymous browsing
Directory	Distributed DHT	Centralized authorities
Outproxies	Limited	Exit nodes
Tunnel Type	Unidirectional	Bidirectional