Router Configuration

Configuration options and formats for I2P routers and clients

Updated: 2025-10 Accurate for: 2.10.0
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Overview

This document provides a comprehensive technical specification of I2P configuration files used by the router and various applications. It covers file format specifications, property definitions, and implementation details verified against the I2P source code and official documentation.

Scope

  • Router configuration files and formats
  • Client application configurations
  • I2PTunnel tunnel configurations
  • File format specifications and implementation
  • Version-specific features and deprecations

Implementation Notes

Configuration files are read and written using DataHelper.loadProps() and storeProps() methods in the I2P core library. The file format differs significantly from the serialized format used in I2P protocols (see Common Structures Specification - Type Mapping).

General Configuration File Format

I2P configuration files follow a modified Java Properties format with specific exceptions and constraints.

Format Specification

Based on Java Properties with the following critical differences:

Encoding

  • MUST use UTF-8 encoding (NOT ISO-8859-1 as in standard Java Properties)
  • Implementation: Uses DataHelper.getUTF8() utilities for all file operations

Escape Sequences

  • NO escape sequences are recognized (including backslash \)
  • Line continuation is NOT supported
  • Backslash characters are treated as literal

Comment Characters

  • # starts a comment in any position on a line
  • ; starts a comment only when in column 1
  • ! does NOT start a comment (differs from Java Properties)

Key-Value Separators

  • = is the ONLY valid key-value separator
  • : is NOT recognized as a separator
  • Whitespace is NOT recognized as a separator

Whitespace Handling

  • Leading and trailing whitespace is NOT trimmed on keys
  • Leading and trailing whitespace IS trimmed on values

Line Processing

  • Lines without = are ignored (treated as comments or blank lines)
  • Empty values (key=) are supported as of version 0.9.10
  • Keys with empty values are stored and retrieved normally

Character Restrictions

Keys may NOT contain:

  • # (hash/pound sign)
  • = (equals sign)
  • \n (newline character)
  • Cannot start with ; (semicolon)

Values may NOT contain:

  • # (hash/pound sign)
  • \n (newline character)
  • Cannot start or end with \r (carriage return)
  • Cannot start or end with whitespace (trimmed automatically)

File Sorting

Configuration files need not be sorted by key. However, most I2P applications sort keys alphabetically when writing configuration files to facilitate:

  • Manual editing
  • Version control diff operations
  • Human readability

Implementation Details

Reading Configuration Files

// Method signature from net.i2p.data.DataHelper
public static Properties loadProps(File file)

Behavior:

  • Reads UTF-8 encoded files
  • Enforces all format rules described above
  • Validates character restrictions
  • Returns empty Properties object if file doesn’t exist
  • Throws IOException for read errors

Writing Configuration Files

// Method signature from net.i2p.data.DataHelper
public static void storeProps(Properties props, File file)

Behavior:

  • Writes UTF-8 encoded files
  • Sorts keys alphabetically (unless OrderedProperties used)
  • Sets file permissions to mode 600 (user read/write only) as of version 0.8.1
  • Throws IllegalArgumentException for invalid characters in keys or values
  • Throws IOException for write errors

Format Validation

The implementation performs strict validation:

  • Keys and values are checked for prohibited characters
  • Invalid entries cause exceptions during write operations
  • Reading silently ignores malformed lines (lines without =)

Format Examples

Valid Configuration File

# This is a comment
; This is also a comment (column 1 only)
key.with.dots=value with spaces
another_key=value=with=equals
empty.value=
numeric.value=12345
unicode.value=こんにちは

Invalid Configuration Examples

# INVALID: Key contains equals sign
invalid=key=value

# INVALID: Key contains hash
invalid#key=value

# INVALID: Value contains newline (implicit)
key=value
continues here

# INVALID: Semicolon comment not in column 1 (treated as key)
 ; not.a.comment=value

Core Library and Router Configuration

Clients Configuration (clients.config)

Location: $I2P_CONFIG_DIR/clients.config (legacy) or $I2P_CONFIG_DIR/clients.config.d/ (modern)
Configuration Interface: Router console at /configclients
Format Change: Version 0.9.42 (August 2019)

Directory Structure (Version 0.9.42+)

As of release 0.9.42, the default clients.config file is automatically split into individual configuration files:

$I2P_CONFIG_DIR/
├── clients.config.d/
│   ├── 00-webConsole.config
│   ├── 01-i2ptunnel.config
│   ├── 02-i2psnark.config
│   ├── 03-susidns.config
│   └── ...
└── clients.config (legacy, auto-migrated)

Migration Behavior:

  • On first run after upgrade to 0.9.42+, monolithic file is split automatically
  • Properties in split files are prefixed with clientApp.0.
  • Legacy format still supported for backward compatibility
  • Split format enables modular packaging and plugin management

Property Format

Lines are of the form clientApp.x.prop=val, where x is the app number.

App numbering requirements:

  • MUST start with 0
  • MUST be consecutive (no gaps)
  • Order determines startup sequence

Required Properties

main
  • Type: String (fully qualified class name)
  • Required: Yes
  • Description: The constructor or main() method in this class will be invoked depending on client type (managed vs. unmanaged)
  • Example: clientApp.0.main=net.i2p.router.web.RouterConsoleRunner

Optional Properties

name
  • Type: String
  • Required: No
  • Description: Display name shown in router console
  • Example: clientApp.0.name=Router Console
args
  • Type: String (space or tab separated)
  • Required: No
  • Description: Arguments passed to main class constructor or main() method
  • Quoting: Arguments containing spaces or tabs may be quoted with ' or "
  • Example: clientApp.0.args=-d $CONFIG/eepsite
delay
  • Type: Integer (seconds)
  • Required: No
  • Default: 120
  • Description: Seconds to wait before starting the client
  • Overrides: Overridden by onBoot=true (sets delay to 0)
  • Special Values:
    • < 0: Wait for router to reach RUNNING state, then start immediately in new thread
    • = 0: Run immediately in same thread (exceptions propagate to console)
    • > 0: Start after delay in new thread (exceptions logged, not propagated)
onBoot
  • Type: Boolean
  • Required: No
  • Default: false
  • Description: Forces delay of 0, overrides explicit delay setting
  • Use Case: Start critical services immediately at router boot
startOnLoad
  • Type: Boolean
  • Required: No
  • Default: true
  • Description: Whether to start the client at all
  • Use Case: Disable clients without removing configuration

Plugin-Specific Properties

These properties are used only by plugins (not core clients):

stopargs
  • Type: String (space or tab separated)
  • Description: Arguments passed to stop the client
  • Variable Substitution: Yes (see below)
uninstallargs
  • Type: String (space or tab separated)
  • Description: Arguments passed to uninstall the client
  • Variable Substitution: Yes (see below)
classpath
  • Type: String (comma-separated paths)
  • Description: Additional classpath elements for the client
  • Variable Substitution: Yes (see below)

Variable Substitution (Plugins Only)

The following variables are substituted in args, stopargs, uninstallargs, and classpath for plugins:

VariableExpands ToExample
$I2PBase I2P installation directory/usr/share/i2p
$CONFIGUser configuration directory~/.i2p
$PLUGINPlugin directory~/.i2p/plugins/foo
$OSOperating system namelinux
$ARCHArchitecture nameamd64

Note: Variable substitution is performed only for plugins, not for core clients.

Client Types

Managed Clients
  • Constructor is called with RouterContext and ClientAppManager parameters
  • Client must implement ClientApp interface
  • Lifecycle controlled by router
  • Can be started, stopped, and restarted dynamically
Unmanaged Clients
  • main(String[] args) method is called
  • Run in separate thread
  • Lifecycle not managed by router
  • Legacy client type

Example Configuration

# Router Console (core client)
clientApp.0.main=net.i2p.router.web.RouterConsoleRunner
clientApp.0.name=Router Console
clientApp.0.args=-d $CONFIG/eepsite
clientApp.0.delay=0
clientApp.0.onBoot=true
clientApp.0.startOnLoad=true

# I2PTunnel (core client)
clientApp.1.main=net.i2p.i2ptunnel.TunnelControllerGroup
clientApp.1.name=I2PTunnel
clientApp.1.args=
clientApp.1.delay=120
clientApp.1.startOnLoad=true

# Plugin Example
clientApp.2.main=org.example.plugin.PluginMain
clientApp.2.name=Example Plugin
clientApp.2.args=-config $PLUGIN/config.properties
clientApp.2.stopargs=-shutdown
clientApp.2.uninstallargs=-remove $PLUGIN
clientApp.2.classpath=$PLUGIN/lib/plugin.jar,$PLUGIN/lib/dep.jar
clientApp.2.delay=240
clientApp.2.startOnLoad=true

Logger Configuration (logger.config)

Location: $I2P_CONFIG_DIR/logger.config
Configuration Interface: Router console at /configlogging

Properties Reference

Console Buffer Configuration
logger.consoleBufferSize
  • Type: Integer
  • Default: 20
  • Description: Maximum number of log messages to buffer in console
  • Range: 1-1000 recommended
Date and Time Formatting
logger.dateFormat
  • Type: String (SimpleDateFormat pattern)
  • Default: From system locale
  • Example: HH:mm:ss.SSS
  • Documentation: Java SimpleDateFormat
Log Levels
logger.defaultLevel
  • Type: Enum
  • Default: ERROR
  • Values: CRIT, ERROR, WARN, INFO, DEBUG
  • Description: Default logging level for all classes
logger.minimumOnScreenLevel
  • Type: Enum
  • Default: CRIT
  • Values: CRIT, ERROR, WARN, INFO, DEBUG
  • Description: Minimum level for messages shown on screen
logger.record.{class}
  • Type: Enum
  • Values: CRIT, ERROR, WARN, INFO, DEBUG
  • Description: Per-class logging level override
  • Example: logger.record.net.i2p.router.transport.udp=DEBUG
Display Options
logger.displayOnScreen
  • Type: Boolean
  • Default: true
  • Description: Whether to display log messages in console output
logger.dropDuplicates
  • Type: Boolean
  • Default: true
  • Description: Drop duplicate consecutive log messages
logger.dropOnOverflow
  • Type: Boolean
  • Default: false
  • Description: Drop messages when buffer is full (vs. blocking)
Flushing Behavior
logger.flushInterval
  • Type: Integer (seconds)
  • Default: 29
  • Since: Version 0.9.18
  • Description: How often to flush log buffer to disk
Format Configuration
logger.format
  • Type: String (character sequence)
  • Description: Log message format template
  • Format Characters:
    • d = date/time
    • c = class name
    • t = thread name
    • p = priority (log level)
    • m = message
  • Example: dctpm produces [timestamp] [class] [thread] [level] message
Compression (Version 0.9.56+)
logger.gzip
  • Type: Boolean
  • Default: false
  • Since: Version 0.9.56
  • Description: Enable gzip compression for rotated log files
logger.minGzipSize
  • Type: Integer (bytes)
  • Default: 65536
  • Since: Version 0.9.56
  • Description: Minimum file size to trigger compression (64 KB default)
File Management
logger.logBufferSize
  • Type: Integer (bytes)
  • Default: 1024
  • Description: Maximum messages to buffer before flushing
logger.logFileName
  • Type: String (file path)
  • Default: logs/log-@.txt
  • Description: Log file naming pattern (@ replaced with rotation number)
logger.logFilenameOverride
  • Type: String (file path)
  • Description: Override for log file name (disables rotation pattern)
logger.logFileSize
  • Type: String (size with unit)
  • Default: 10M
  • Units: K (kilobytes), M (megabytes), G (gigabytes)
  • Example: 50M, 1G
logger.logRotationLimit
  • Type: Integer
  • Default: 2
  • Description: Highest rotation file number (log-0.txt through log-N.txt)

Example Configuration

# Basic logging configuration
logger.consoleBufferSize=50
logger.dateFormat=yyyy-MM-dd HH:mm:ss.SSS
logger.defaultLevel=WARN
logger.displayOnScreen=true
logger.dropDuplicates=true
logger.dropOnOverflow=false

# Flushing and format
logger.flushInterval=30
logger.format=dctpm

# File management
logger.logBufferSize=2048
logger.logFileName=logs/log-@.txt
logger.logFileSize=25M
logger.logRotationLimit=5

# Compression (0.9.56+)
logger.gzip=true
logger.minGzipSize=131072

# On-screen filtering
logger.minimumOnScreenLevel=ERROR

# Per-class overrides
logger.record.net.i2p.router.transport=INFO
logger.record.net.i2p.router.tunnel=DEBUG
logger.record.net.i2p.crypto=WARN

Plugin Configuration

Individual Plugin Configuration (plugins/*/plugin.config)

Location: $I2P_CONFIG_DIR/plugins/{plugin-name}/plugin.config
Format: Standard I2P configuration file format
Documentation: Plugin Specification

Required Properties
name
  • Type: String
  • Required: Yes
  • Description: Plugin display name
  • Example: name=I2P Plugin Example
key
  • Type: String (public key)
  • Required: Yes (omit for SU3 signed plugins)
  • Description: Plugin signing public key for verification
  • Format: Base64-encoded signing key
signer
  • Type: String
  • Required: Yes
  • Description: Plugin signer identity
  • Example: signer=user@example.i2p
version
  • Type: String (VersionComparator format)
  • Required: Yes
  • Description: Plugin version for update checking
  • Format: Semantic versioning or custom comparable format
  • Example: version=1.2.3
Display Properties
date
  • Type: Long (Unix timestamp milliseconds)
  • Description: Plugin release date
author
  • Type: String
  • Description: Plugin author name
websiteURL
  • Type: String (URL)
  • Description: Plugin website URL
updateURL
  • Type: String (URL)
  • Description: Update check URL for plugin
updateURL.su3
  • Type: String (URL)
  • Since: Version 0.9.15
  • Description: SU3 format update URL (preferred)
description
  • Type: String
  • Description: English plugin description
description_{language}
  • Type: String
  • Description: Localized plugin description
  • Example: description_de=Deutsche Beschreibung
license
  • Type: String
  • Description: Plugin license identifier
  • Example: license=Apache 2.0
Installation Properties
dont-start-at-install
  • Type: Boolean
  • Default: false
  • Description: Prevent automatic start after installation
router-restart-required
  • Type: Boolean
  • Default: false
  • Description: Require router restart after installation
install-only
  • Type: Boolean
  • Default: false
  • Description: Install once only (no updates)
update-only
  • Type: Boolean
  • Default: false
  • Description: Update existing installation only (no fresh install)
Example Plugin Configuration
# Required properties
name=Example I2P Plugin
signer=developer@mail.i2p
version=1.5.0

# Display properties
author=Plugin Developer
websiteURL=http://plugin.example.i2p
updateURL=http://plugin.example.i2p/update.xpi2p
updateURL.su3=http://plugin.example.i2p/update.su3
description=Example plugin demonstrating configuration
description_de=Beispiel-Plugin zur Demonstration der Konfiguration
license=MIT

# Installation behavior
dont-start-at-install=false
router-restart-required=false

Global Plugin Configuration (plugins.config)

Location: $I2P_CONFIG_DIR/plugins.config
Purpose: Enable/disable installed plugins globally

Property Format
plugin.{name}.startOnLoad=true|false
  • {name}: Plugin name from plugin.config
  • startOnLoad: Whether to start plugin at router launch
Example
plugin.i2psnark.startOnLoad=true
plugin.susimail.startOnLoad=true
plugin.susidns.startOnLoad=true
plugin.i2pbote.startOnLoad=false

Web Applications Configuration (webapps.config)

Location: $I2P_CONFIG_DIR/webapps.config
Purpose: Enable/disable and configure web applications

Property Format

webapps.{name}.startOnLoad
  • Type: Boolean
  • Description: Whether to start webapp at router launch
  • Format: webapps.{name}.startOnLoad=true|false
webapps.{name}.classpath
  • Type: String (space or comma-separated paths)
  • Description: Additional classpath elements for webapp
  • Format: webapps.{name}.classpath=[paths]

Variable Substitution

Paths support the following variable substitutions:

VariableExpands ToContext
$I2PBase I2P directoryCore webapps
$CONFIGUser config directoryAll webapps
$PLUGINPlugin directoryPlugin webapps

Classpath Resolution

  • Core webapps: Paths relative to $I2P/lib
  • Plugin webapps: Paths relative to $CONFIG/plugins/{appname}/lib

Example Configuration

# Router console
webapps.routerconsole.startOnLoad=true
webapps.routerconsole.classpath=routerconsole.jar

# I2PSnark
webapps.i2psnark.startOnLoad=true
webapps.i2psnark.classpath=i2psnark.jar

# SusiDNS
webapps.susidns.startOnLoad=true
webapps.susidns.classpath=susidns.jar

# Plugin webapp example
webapps.exampleplugin.startOnLoad=false
webapps.exampleplugin.classpath=$PLUGIN/lib/webapp.jar,$PLUGIN/lib/deps.jar

Router Configuration (router.config)

Location: $I2P_CONFIG_DIR/router.config
Configuration Interface: Router console at /configadvanced
Purpose: Core router settings and network parameters

Configuration Categories

Network Configuration

Bandwidth settings:

i2np.bandwidth.inboundKBytesPerSecond=100
i2np.bandwidth.outboundKBytesPerSecond=50
i2np.bandwidth.share.percentage=80

Transport configuration:

# NTCP (TCP-based transport)
i2np.ntcp.port=8887
i2np.ntcp.enable=true
i2np.ntcp.autoip=true

# SSU (UDP-based transport)
i2np.udp.port=8887
i2np.udp.enable=true

# UPnP/NAT-PMP
i2np.upnp.enable=true
Router Behavior
# Tunnel participation
router.maxParticipatingTunnels=200
router.sharePercentage=80

# Updates
router.updatePolicy=notify
router.updateURL=http://update.i2p2.i2p/

# Network integration
router.hiddenMode=false
router.clockSkewOffset=0
Console Configuration
# Language and display
routerconsole.lang=en
routerconsole.country=US
routerconsole.summaryRefresh=60

# Browser
routerconsole.browser=default

# Security
routerconsole.enableCompression=true
Time Configuration
# NTP
time.disabled=false
time.sntpServerList=0.pool.ntp.org,1.pool.ntp.org

Note: Router configuration is extensive. See router console at /configadvanced for complete property reference.

Application Configuration Files

Address Book Configuration (addressbook/config.txt)

Location: $I2P_CONFIG_DIR/addressbook/config.txt
Application: SusiDNS
Purpose: Hostname resolution and address book management

File Locations

router_addressbook
  • Default: ../hosts.txt
  • Description: Master address book (system-wide hostnames)
  • Format: Standard hosts file format
privatehosts.txt
  • Location: $I2P_CONFIG_DIR/addressbook/privatehosts.txt
  • Description: Private hostname mappings
  • Priority: Highest (overrides all other sources)
userhosts.txt
  • Location: $I2P_CONFIG_DIR/addressbook/userhosts.txt
  • Description: User-added hostname mappings
  • Management: Via SusiDNS interface
hosts.txt
  • Location: $I2P_CONFIG_DIR/addressbook/hosts.txt
  • Description: Downloaded public address book
  • Source: Subscription feeds

Naming Service

BlockfileNamingService (Default since 0.8.8)

Storage format:

  • File: hostsdb.blockfile
  • Location: $I2P_CONFIG_DIR/addressbook/
  • Performance: ~10x faster lookups than hosts.txt
  • Format: Binary database format

Legacy naming service:

  • Format: Plain text hosts.txt
  • Status: Deprecated but still supported
  • Use Case: Manual editing, version control

Hostname Rules

I2P hostnames must conform to:

  1. TLD requirement: Must end with .i2p
  2. Maximum length: 67 characters total
  3. Character set: [a-z], [0-9], . (period), - (hyphen)
  4. Case: Lowercase only
  5. Start restrictions: Cannot start with . or -
  6. Forbidden patterns: Cannot contain .., .-, or -. (since 0.6.1.33)
  7. Reserved: Base32 hostnames *.b32.i2p (52 chars of base32.b32.i2p)
Valid Examples
example.i2p
my-site.i2p
test.example.i2p
site123.i2p
Invalid Examples
example.com          # Wrong TLD
-invalid.i2p         # Starts with hyphen
invalid..i2p         # Contains double dot
invalid.-.i2p        # Contains dot-hyphen
UPPERCASE.I2P        # Must be lowercase
verylonghostnameover67charactersthatexceedsthemaximumlength.i2p  # Too long

Subscription Management

subscriptions.txt
  • Location: $I2P_CONFIG_DIR/addressbook/subscriptions.txt
  • Format: One URL per line
  • Default: http://i2p-projekt.i2p/hosts.txt
Subscription Feed Format (Since 0.9.26)

Advanced feed format with metadata:

#
# I2P Address Book Subscription Feed
# Format: hostname=destination [#property=value ...]
#

example.i2p=base64destination #added=20250101 #src=manual
another.i2p=base64destination #added=20250102 #src=feed1

Metadata properties:

  • added: Date hostname was added (YYYYMMDD format)
  • src: Source identifier
  • sig: Optional signature

Backward compatibility: Simple hostname=destination format still supported.

Example Configuration

# Address book locations
router_addressbook=../hosts.txt
privatehosts.txt=$CONFIG/addressbook/privatehosts.txt
userhosts.txt=$CONFIG/addressbook/userhosts.txt
hosts.txt=$CONFIG/addressbook/hosts.txt

# Naming service
naming.service=BlockfileNamingService
naming.service.blockfile.location=$CONFIG/addressbook/hostsdb.blockfile

# Subscriptions
subscriptions.txt=$CONFIG/addressbook/subscriptions.txt
subscriptions.schedule=daily
subscriptions.proxy=false

I2PSnark Configuration (i2psnark.config.d/i2psnark.config)

Location: $I2P_CONFIG_DIR/i2psnark.config.d/i2psnark.config
Application: I2PSnark BitTorrent client
Configuration Interface: Web GUI at http://127.0.0.1:7657/i2psnark

Directory Structure

$I2P_CONFIG_DIR/i2psnark.config.d/
├── i2psnark.config
├── [torrent-hash-1]/
│   └── *.config
├── [torrent-hash-2]/
│   └── *.config
└── ...

Main Configuration (i2psnark.config)

Minimal default configuration:

i2psnark.dir=i2psnark

Additional properties managed via web interface:

# Basic settings
i2psnark.dir=i2psnark
i2psnark.autoStart=false
i2psnark.openTrackers=true

# Network settings
i2psnark.uploaders=8
i2psnark.upBW=40
i2psnark.seedPct=100

# I2CP settings
i2psnark.i2cpHost=127.0.0.1
i2psnark.i2cpPort=7654

Individual Torrent Configuration

Location: $I2P_CONFIG_DIR/i2psnark.config.d/[torrent-hash]/*.config
Format: Per-torrent settings
Management: Automatic (via web GUI)

Properties include:

  • Torrent-specific upload/download settings
  • File priorities
  • Tracker information
  • Peer limits

Note: Torrent configurations are primarily managed through the web interface. Manual editing is not recommended.

Torrent Data Organization

Data storage is separate from configuration:

$I2P_CONFIG_DIR/i2psnark/          # Data directory
├── *.torrent                       # Torrent metadata files
├── *.torrent.downloaded/           # Downloaded file directories
├── file1.dat                       # Direct file downloads
└── ...

$I2P_CONFIG_DIR/i2psnark.config.d/ # Configuration directory
├── i2psnark.config                 # Main config
└── [hashes]/                       # Per-torrent configs

I2PTunnel Configuration (i2ptunnel.config)

Location: $I2P_CONFIG_DIR/i2ptunnel.config (legacy) or $I2P_CONFIG_DIR/i2ptunnel.config.d/ (modern)
Configuration Interface: Router console at /i2ptunnel
Format Change: Version 0.9.42 (August 2019)

Directory Structure (Version 0.9.42+)

As of release 0.9.42, the default i2ptunnel.config file is automatically split:

$I2P_CONFIG_DIR/
├── i2ptunnel.config.d/
│   ├── http-proxy/
│   │   └── tunnel.config
│   ├── irc-proxy/
│   │   └── tunnel.config
│   ├── ssh-service/
│   │   └── tunnel.config
│   └── ...
└── i2ptunnel.config (legacy, auto-migrated)

Critical Format Difference:

  • Monolithic format: Properties prefixed with tunnel.N.
  • Split format: Properties NOT prefixed (e.g., description=, not tunnel.0.description=)

Migration Behavior

On first run after upgrade to 0.9.42:

  1. Existing i2ptunnel.config is read
  2. Individual tunnel configs created in i2ptunnel.config.d/
  3. Properties are de-prefixed in split files
  4. Original file backed up
  5. Legacy format still supported for backward compatibility

Configuration Sections

The I2PTunnel configuration is documented in detail in the I2PTunnel Configuration Reference section below. Property descriptions are applicable to both monolithic (tunnel.N.property) and split (property) formats.

I2PTunnel Configuration Reference

This section provides comprehensive technical reference for all I2PTunnel configuration properties. Properties are shown in split format (without tunnel.N. prefix). For monolithic format, prefix all properties with tunnel.N. where N is the tunnel number.

Important: Properties described as tunnel.N.option.i2cp.* are implemented in I2PTunnel and are NOT supported via other interfaces such as I2CP protocol or SAM API.

Basic Properties

tunnel.N.description (description)

  • Type: String
  • Context: All tunnels
  • Description: Human-readable tunnel description for UI display
  • Example: description=HTTP Proxy for outproxy access

tunnel.N.name (name)

  • Type: String
  • Context: All tunnels
  • Required: Yes
  • Description: Unique tunnel identifier and display name
  • Example: name=I2P HTTP Proxy

tunnel.N.type (type)

  • Type: Enum
  • Context: All tunnels
  • Required: Yes
  • Values:
    • client - Generic client tunnel
    • httpclient - HTTP proxy client
    • ircclient - IRC client tunnel
    • socksirctunnel - SOCKS IRC proxy
    • sockstunnel - SOCKS proxy (version 4, 4a, 5)
    • connectclient - CONNECT proxy client
    • streamrclient - Streamr client
    • server - Generic server tunnel
    • httpserver - HTTP server tunnel
    • ircserver - IRC server tunnel
    • httpbidirserver - Bidirectional HTTP server
    • streamrserver - Streamr server

tunnel.N.interface (interface)

  • Type: String (IP address or hostname)
  • Context: Client tunnels only
  • Default: 127.0.0.1
  • Description: Local interface to bind for incoming connections
  • Security Note: Binding to 0.0.0.0 allows remote connections
  • Example: interface=127.0.0.1

tunnel.N.listenPort (listenPort)

  • Type: Integer
  • Context: Client tunnels only
  • Range: 1-65535
  • Description: Local port to listen on for client connections
  • Example: listenPort=4444

tunnel.N.targetHost (targetHost)

  • Type: String (IP address or hostname)
  • Context: Server tunnels only
  • Description: Local server to forward connections to
  • Example: targetHost=127.0.0.1

tunnel.N.targetPort (targetPort)

  • Type: Integer
  • Context: Server tunnels only
  • Range: 1-65535
  • Description: Port on targetHost to connect to
  • Example: targetPort=80

tunnel.N.targetDestination (targetDestination)

  • Type: String (comma or space-separated destinations)
  • Context: Client tunnels only
  • Format: destination[:port][,destination[:port]]
  • Description: I2P destination(s) to connect to
  • Examples:
    • targetDestination=example.i2p
    • targetDestination=example.i2p:8080
    • targetDestination=site1.i2p,site2.i2p:8080

tunnel.N.i2cpHost (i2cpHost)

  • Type: String (IP address or hostname)
  • Default: 127.0.0.1
  • Description: I2P router I2CP interface address
  • Note: Ignored when running in router context
  • Example: i2cpHost=127.0.0.1

tunnel.N.i2cpPort (i2cpPort)

  • Type: Integer
  • Default: 7654
  • Range: 1-65535
  • Description: I2P router I2CP port
  • Note: Ignored when running in router context
  • Example: i2cpPort=7654

tunnel.N.startOnLoad (startOnLoad)

  • Type: Boolean
  • Default: true
  • Description: Whether to start tunnel when I2PTunnel loads
  • Example: startOnLoad=true

Proxy Configuration

tunnel.N.proxyList (proxyList)

  • Type: String (comma or space-separated hostnames)
  • Context: HTTP and SOCKS proxies only
  • Description: List of outproxy hosts
  • Example: proxyList=outproxy.example.i2p,backup.example.i2p

Server Configuration

tunnel.N.privKeyFile (privKeyFile)

  • Type: String (file path)
  • Context: Servers and persistent client tunnels
  • Description: File containing persistent destination private keys
  • Path: Absolute or relative to I2P config directory
  • Example: privKeyFile=eepsite/eepPriv.dat

tunnel.N.spoofedHost (spoofedHost)

  • Type: String (hostname)
  • Context: HTTP servers only
  • Default: Base32 hostname of destination
  • Description: Host header value passed to local server
  • Example: spoofedHost=example.i2p

tunnel.N.spoofedHost.NNNN (spoofedHost.NNNN)

  • Type: String (hostname)
  • Context: HTTP servers only
  • Description: Virtual host override for specific incoming port
  • Use Case: Host multiple sites on different ports
  • Example: spoofedHost.8080=site1.example.i2p

Client-Specific Options

tunnel.N.sharedClient (sharedClient)

  • Type: Boolean
  • Context: Client tunnels only
  • Default: false
  • Description: Whether multiple clients can share this tunnel
  • Example: sharedClient=false

tunnel.N.option.persistentClientKey (persistentClientKey)

  • Type: Boolean
  • Context: Client tunnels only
  • Default: false
  • Description: Store and reuse destination keys across restarts
  • Conflict: Mutually exclusive with i2cp.newDestOnResume=true
  • Example: option.persistentClientKey=true

I2CP Options (I2PTunnel Implementation)

Important: These properties are prefixed with option.i2cp. but are implemented in I2PTunnel, not in the I2CP protocol layer. They are not available via I2CP or SAM APIs.

tunnel.N.option.i2cp.delayOpen (option.i2cp.delayOpen)

  • Type: Boolean
  • Context: Client tunnels only
  • Default: false
  • Description: Delay tunnel creation until first connection
  • Use Case: Save resources for rarely-used tunnels
  • Example: option.i2cp.delayOpen=false

tunnel.N.option.i2cp.newDestOnResume (option.i2cp.newDestOnResume)

  • Type: Boolean
  • Context: Client tunnels only
  • Default: false
  • Requires: i2cp.closeOnIdle=true
  • Conflict: Mutually exclusive with persistentClientKey=true
  • Description: Create new destination after idle timeout
  • Example: option.i2cp.newDestOnResume=false

tunnel.N.option.i2cp.leaseSetPrivateKey (option.i2cp.leaseSetPrivateKey)

  • Type: String (base64-encoded key)
  • Context: Server tunnels only
  • Description: Persistent private leaseset encryption key
  • Use Case: Maintain consistent encrypted leaseset across restarts
  • Example: option.i2cp.leaseSetPrivateKey=AAAA...base64...

tunnel.N.option.i2cp.leaseSetSigningPrivateKey (option.i2cp.leaseSetSigningPrivateKey)

  • Type: String (sigtype:base64)
  • Context: Server tunnels only
  • Format: sigtype:base64key
  • Description: Persistent leaseset signing private key
  • Example: option.i2cp.leaseSetSigningPrivateKey=7:AAAA...base64...

Server-Specific Options

tunnel.N.option.enableUniqueLocal (option.enableUniqueLocal)

  • Type: Boolean
  • Context: Server tunnels only
  • Default: false
  • Description: Use unique local IP per remote I2P destination
  • Use Case: Track client IPs in server logs
  • Security Note: May reduce anonymity
  • Example: option.enableUniqueLocal=false

tunnel.N.option.targetForPort.NNNN (option.targetForPort.NNNN)

  • Type: String (hostname:port)
  • Context: Server tunnels only
  • Description: Override targetHost/targetPort for incoming port NNNN
  • Use Case: Port-based routing to different local services
  • Example: option.targetForPort.8080=localhost:8080

Thread Pool Configuration

tunnel.N.option.i2ptunnel.usePool (option.i2ptunnel.usePool)

  • Type: Boolean
  • Context: Server tunnels only
  • Default: true
  • Description: Use thread pool for connection handling
  • Note: Always false for standard servers (ignored)
  • Example: option.i2ptunnel.usePool=true

tunnel.N.option.i2ptunnel.blockingHandlerCount (option.i2ptunnel.blockingHandlerCount)

  • Type: Integer
  • Context: Server tunnels only
  • Default: 65
  • Description: Maximum thread pool size
  • Note: Ignored for standard servers
  • Example: option.i2ptunnel.blockingHandlerCount=100

HTTP Client Options

tunnel.N.option.i2ptunnel.httpclient.allowInternalSSL (option.i2ptunnel.httpclient.allowInternalSSL)

  • Type: Boolean
  • Context: HTTP clients only
  • Default: false
  • Description: Allow SSL connections to .i2p addresses
  • Example: option.i2ptunnel.httpclient.allowInternalSSL=false

tunnel.N.option.i2ptunnel.httpclient.disableAddressHelper (option.i2ptunnel.httpclient.disableAddressHelper)

  • Type: Boolean
  • Context: HTTP clients only
  • Default: false
  • Description: Disable address helper links in proxy responses
  • Example: option.i2ptunnel.httpclient.disableAddressHelper=false

tunnel.N.option.i2ptunnel.httpclient.jumpServers (option.i2ptunnel.httpclient.jumpServers)

  • Type: String (comma or space-separated URLs)
  • Context: HTTP clients only
  • Description: Jump server URLs for hostname resolution
  • Example: option.i2ptunnel.httpclient.jumpServers=http://jump.i2p/jump,http://stats.i2p/jump

tunnel.N.option.i2ptunnel.httpclient.sendAccept (option.i2ptunnel.httpclient.sendAccept)

  • Type: Boolean
  • Context: HTTP clients only
  • Default: false
  • Description: Pass Accept-* headers (except Accept and Accept-Encoding)
  • Example: option.i2ptunnel.httpclient.sendAccept=false

tunnel.N.option.i2ptunnel.httpclient.sendReferer (option.i2ptunnel.httpclient.sendReferer)

  • Type: Boolean
  • Context: HTTP clients only
  • Default: false
  • Description: Pass Referer headers through proxy
  • Privacy Note: May leak information
  • Example: option.i2ptunnel.httpclient.sendReferer=false

tunnel.N.option.i2ptunnel.httpclient.sendUserAgent (option.i2ptunnel.httpclient.sendUserAgent)

  • Type: Boolean
  • Context: HTTP clients only
  • Default: false
  • Description: Pass User-Agent headers through proxy
  • Privacy Note: May leak browser information
  • Example: option.i2ptunnel.httpclient.sendUserAgent=false

tunnel.N.option.i2ptunnel.httpclient.sendVia (option.i2ptunnel.httpclient.sendVia)

  • Type: Boolean
  • Context: HTTP clients only
  • Default: false
  • Description: Pass Via headers through proxy
  • Example: option.i2ptunnel.httpclient.sendVia=false

tunnel.N.option.i2ptunnel.httpclient.SSLOutproxies (option.i2ptunnel.httpclient.SSLOutproxies)

  • Type: String (comma or space-separated destinations)
  • Context: HTTP clients only
  • Description: In-network SSL outproxies for HTTPS
  • Example: option.i2ptunnel.httpclient.SSLOutproxies=ssl-outproxy.i2p

tunnel.N.option.i2ptunnel.useLocalOutproxy (option.i2ptunnel.useLocalOutproxy)

  • Type: Boolean
  • Context: HTTP clients only
  • Default: true
  • Description: Use registered local outproxy plugins
  • Example: option.i2ptunnel.useLocalOutproxy=true

HTTP Client Authentication

tunnel.N.option.proxyAuth (option.proxyAuth)

  • Type: Enum
  • Context: HTTP clients only
  • Default: false
  • Values: true, false, basic, digest
  • Description: Require local authentication for proxy access
  • Note: true is equivalent to basic
  • Example: option.proxyAuth=basic

tunnel.N.option.proxy.auth.USER.md5 (option.proxy.auth.USER.md5)

  • Type: String (32 character lowercase hex)
  • Context: HTTP clients only
  • Requires: proxyAuth=basic or proxyAuth=digest
  • Description: MD5 hash of password for user USER
  • Deprecation: Use SHA-256 instead (0.9.56+)
  • Example: option.proxy.auth.alice.md5=5f4dcc3b5aa765d61d8327deb882cf99

tunnel.N.option.proxy.auth.USER.sha256 (option.proxy.auth.USER.sha256)

  • Type: String (64 character lowercase hex)
  • Context: HTTP clients only
  • Requires: proxyAuth=digest
  • Since: Version 0.9.56
  • Standard: RFC 7616
  • Description: SHA-256 hash of password for user USER
  • Example: option.proxy.auth.alice.sha256=5e884898da28047151d0e56f8dc6292773603d0d6aabbdd62a11ef721d1542d8

Outproxy Authentication

tunnel.N.option.outproxyAuth (option.outproxyAuth)

  • Type: Boolean
  • Context: HTTP clients only
  • Default: false
  • Description: Send authentication to outproxy
  • Example: option.outproxyAuth=false

tunnel.N.option.outproxyUsername (option.outproxyUsername)

  • Type: String
  • Context: HTTP clients only
  • Requires: outproxyAuth=true
  • Description: Username for outproxy authentication
  • Example: option.outproxyUsername=user

tunnel.N.option.outproxyPassword (option.outproxyPassword)

  • Type: String
  • Context: HTTP clients only
  • Requires: outproxyAuth=true
  • Description: Password for outproxy authentication
  • Security: Stored in plaintext
  • Example: option.outproxyPassword=secret

SOCKS Client Options

tunnel.N.option.i2ptunnel.socks.proxy.default (option.i2ptunnel.socks.proxy.default)

  • Type: String (comma or space-separated destinations)
  • Context: SOCKS clients only
  • Description: In-network outproxies for unspecified ports
  • Example: option.i2ptunnel.socks.proxy.default=outproxy.i2p

tunnel.N.option.i2ptunnel.socks.proxy.NNNN (option.i2ptunnel.socks.proxy.NNNN)

  • Type: String (comma or space-separated destinations)
  • Context: SOCKS clients only
  • Description: In-network outproxies for port NNNN specifically
  • Example: option.i2ptunnel.socks.proxy.443=ssl-outproxy.i2p

tunnel.N.option.outproxyType (option.outproxyType)

  • Type: Enum
  • Context: SOCKS clients only
  • Default: socks
  • Since: Version 0.9.57
  • Values: socks, connect (HTTPS)
  • Description: Type of configured outproxy
  • Example: option.outproxyType=connect

HTTP Server Options

tunnel.N.option.maxPosts (option.maxPosts)

  • Type: Integer
  • Context: HTTP servers only
  • Default: 0 (unlimited)
  • Description: Max POSTs from one destination per postCheckTime
  • Example: option.maxPosts=10

tunnel.N.option.maxTotalPosts (option.maxTotalPosts)

  • Type: Integer
  • Context: HTTP servers only
  • Default: 0 (unlimited)
  • Description: Max POSTs from all destinations per postCheckTime
  • Example: option.maxTotalPosts=50

tunnel.N.option.postCheckTime (option.postCheckTime)

  • Type: Integer (seconds)
  • Context: HTTP servers only
  • Default: 300
  • Description: Time window for checking POST limits
  • Example: option.postCheckTime=600

tunnel.N.option.postBanTime (option.postBanTime)

  • Type: Integer (seconds)
  • Context: HTTP servers only
  • Default: 1800
  • Description: Ban duration after maxPosts exceeded for single destination
  • Example: option.postBanTime=3600

tunnel.N.option.postTotalBanTime (option.postTotalBanTime)

  • Type: Integer (seconds)
  • Context: HTTP servers only
  • Default: 600
  • Description: Ban duration after maxTotalPosts exceeded
  • Example: option.postTotalBanTime=1200

HTTP Server Security Options

tunnel.N.option.rejectInproxy (option.rejectInproxy)

  • Type: Boolean
  • Context: HTTP servers only
  • Default: false
  • Description: Reject connections apparently via an inproxy
  • Example: option.rejectInproxy=false

tunnel.N.option.rejectReferer (option.rejectReferer)

  • Type: Boolean
  • Context: HTTP servers only
  • Default: false
  • Since: Version 0.9.25
  • Description: Reject connections with Referer header
  • Example: option.rejectReferer=false

tunnel.N.option.rejectUserAgents (option.rejectUserAgents)

  • Type: Boolean
  • Context: HTTP servers only
  • Default: false
  • Since: Version 0.9.25
  • Requires: userAgentRejectList property
  • Description: Reject connections with matching User-Agent
  • Example: option.rejectUserAgents=false

tunnel.N.option.userAgentRejectList (option.userAgentRejectList)

  • Type: String (comma-separated match strings)
  • Context: HTTP servers only
  • Since: Version 0.9.25
  • Case: Case-sensitive matching
  • Special: “none” (since 0.9.33) matches empty User-Agent
  • Description: List of User-Agent patterns to reject
  • Example: option.userAgentRejectList=Mozilla,Opera,none

IRC Server Options

tunnel.N.option.ircserver.fakeHostname (option.ircserver.fakeHostname)

  • Type: String (hostname pattern)
  • Context: IRC servers only
  • Default: %f.b32.i2p
  • Tokens:
    • %f = Full base32 destination hash
    • %c = Cloaked destination hash (see cloakKey)
  • Description: Hostname format sent to IRC server
  • Example: option.ircserver.fakeHostname=%c.irc.i2p

tunnel.N.option.ircserver.cloakKey (option.ircserver.cloakKey)

  • Type: String (passphrase)
  • Context: IRC servers only
  • Default: Random per session
  • Restrictions: No quotes or spaces
  • Description: Passphrase for consistent hostname cloaking
  • Use Case: Persistent user tracking across restarts/servers
  • Example: option.ircserver.cloakKey=mysecretkey

tunnel.N.option.ircserver.method (option.ircserver.method)

  • Type: Enum
  • Context: IRC servers only
  • Default: user
  • Values: user, webirc
  • Description: Authentication method for IRC server
  • Example: option.ircserver.method=webirc

tunnel.N.option.ircserver.webircPassword (option.ircserver.webircPassword)

  • Type: String (password)
  • Context: IRC servers only
  • Requires: method=webirc
  • Restrictions: No quotes or spaces
  • Description: Password for WEBIRC protocol authentication
  • Example: option.ircserver.webircPassword=webircpass

tunnel.N.option.ircserver.webircSpoofIP (option.ircserver.webircSpoofIP)

  • Type: String (IP address)
  • Context: IRC servers only
  • Requires: method=webirc
  • Description: Spoofed IP address for WEBIRC protocol
  • Example: option.ircserver.webircSpoofIP=10.0.0.1

SSL/TLS Configuration

tunnel.N.option.useSSL (option.useSSL)

  • Type: Boolean
  • Default: false
  • Context: All tunnels
  • Behavior:
    • Servers: Use SSL for connections to local server
    • Clients: Require SSL from local clients
  • Example: option.useSSL=false

tunnel.N.option.keystoreFile (option.keystoreFile)

  • Type: String (file path)
  • Context: Client tunnels only
  • Default: i2ptunnel-(random).ks
  • Path: Relative to $(I2P_CONFIG_DIR)/keystore/ if not absolute
  • Auto-generated: Created if doesn’t exist
  • Description: Keystore file containing SSL private key
  • Example: option.keystoreFile=my-tunnel.ks

tunnel.N.option.keystorePassword (option.keystorePassword)

  • Type: String (password)
  • Context: Client tunnels only
  • Default: changeit
  • Auto-generated: Random password if new keystore created
  • Description: Password for SSL keystore
  • Example: option.keystorePassword=secretpassword

tunnel.N.option.keyAlias (option.keyAlias)

  • Type: String (alias)
  • Context: Client tunnels only
  • Auto-generated: Created if new key generated
  • Description: Alias for private key in keystore
  • Example: option.keyAlias=mytunnel-key

tunnel.N.option.keyPassword (option.keyPassword)

  • Type: String (password)
  • Context: Client tunnels only
  • Auto-generated: Random password if new key created
  • Description: Password for private key in keystore
  • Example: option.keyPassword=keypass123

Generic I2CP and Streaming Options

All tunnel.N.option.* properties (not specifically documented above) are passed through to the I2CP interface and streaming library with the tunnel.N.option. prefix stripped.

Important: These are separate from I2PTunnel-specific options. Refer to:

Example streaming options:

option.i2cp.messageReliability=BestEffort
option.i2p.streaming.connectDelay=1000
option.i2p.streaming.maxWindowSize=128

Complete Tunnel Example

# HTTP Proxy (split format without tunnel.N. prefix)
name=I2P HTTP Proxy
description=HTTP proxy for accessing I2P sites and outproxy
type=httpclient
interface=127.0.0.1
listenPort=4444
targetDestination=
sharedClient=true
startOnLoad=true

# I2CP configuration
i2cpHost=127.0.0.1
i2cpPort=7654

# HTTP client options
option.i2ptunnel.httpclient.allowInternalSSL=false
option.i2ptunnel.httpclient.disableAddressHelper=false
option.i2ptunnel.httpclient.jumpServers=http://stats.i2p/cgi-bin/jump.cgi
option.i2ptunnel.httpclient.sendAccept=false
option.i2ptunnel.httpclient.sendReferer=false
option.i2ptunnel.httpclient.sendUserAgent=false

# Proxy authentication
option.proxyAuth=false

# Outproxy configuration
option.i2ptunnel.httpclient.SSLOutproxies=false.i2p
proxyList=false.i2p

# Client behavior
option.persistentClientKey=false
option.i2cp.delayOpen=false

# I2CP tunnel options
option.inbound.length=3
option.outbound.length=3
option.inbound.quantity=2
option.outbound.quantity=2

Version History and Feature Timeline

Version 0.9.10 (2013)

Feature: Empty value support in configuration files

  • Keys with empty values (key=) now supported
  • Previously ignored or caused parsing errors

Version 0.9.18 (2015)

Feature: Logger flush interval configuration

  • Property: logger.flushInterval (default 29 seconds)
  • Reduces disk I/O while maintaining acceptable log latency

Version 0.9.23 (November 2015)

Major Change: Java 7 minimum requirement

  • Java 6 support ended
  • Required for continued security updates

Version 0.9.25 (2015)

Features: HTTP server security options

  • tunnel.N.option.rejectReferer - Reject connections with Referer header
  • tunnel.N.option.rejectUserAgents - Reject specific User-Agent headers
  • tunnel.N.option.userAgentRejectList - User-Agent patterns to reject
  • Use Case: Mitigate crawlers and unwanted clients

Version 0.9.33 (January 2018)

Feature: Enhanced User-Agent filtering

  • userAgentRejectList string “none” matches empty User-Agent
  • Additional bug fixes for i2psnark, i2ptunnel, streaming, SusiMail

Version 0.9.41 (2019)

Deprecation: BOB Protocol removed from Android

  • Android users must migrate to SAM or I2CP

Version 0.9.42 (August 2019)

Major Change: Configuration file splitting

  • clients.config split into clients.config.d/ directory structure
  • i2ptunnel.config split into i2ptunnel.config.d/ directory structure
  • Automatic migration on first run after upgrade
  • Enables modular packaging and plugin management
  • Legacy monolithic format still supported

Additional Features:

  • SSU performance improvements
  • Cross-network prevention (Proposal 147)
  • Initial encryption type support

Version 0.9.56 (2021)

Features: Security and logging improvements

  • logger.gzip - Gzip compression for rotated logs (default: false)
  • logger.minGzipSize - Minimum size for compression (default: 65536 bytes)
  • tunnel.N.option.proxy.auth.USER.sha256 - SHA-256 digest authentication (RFC 7616)
  • Security: SHA-256 replaces MD5 for digest authentication

Version 0.9.57 (January 2023)

Feature: SOCKS outproxy type configuration

  • tunnel.N.option.outproxyType - Select outproxy type (socks|connect)
  • Default: socks
  • HTTPS CONNECT support for HTTPS outproxies

Version 2.6.0 (July 2024)

Breaking Change: I2P-over-Tor blocked

  • Connections from Tor exit node IP addresses now rejected
  • Reason: Degrades I2P performance, wastes Tor exit resources
  • Impact: Users accessing I2P through Tor exit nodes will be blocked
  • Non-exit relays and Tor clients unaffected

Version 2.10.0 (September 2025 - Current)

Major Features:

  • Post-quantum cryptography available (opt-in via Hidden Service Manager)
  • UDP tracker support for I2PSnark to reduce tracker load
  • Hidden Mode stability improvements to reduce RouterInfo depletion
  • Network improvements for congested routers
  • Enhanced UPnP/NAT traversal
  • NetDB improvements with aggressive leaseset removal
  • Observability reductions for router events

Configuration: No new configuration properties added

Critical Upcoming Change: Next release (likely 2.11.0 or 3.0.0) will require Java 17 or later

Deprecations and Breaking Changes

Critical Deprecations

I2P-over-Tor Access (Version 2.6.0+)

  • Status: BLOCKED since July 2024
  • Impact: Connections from Tor exit node IPs rejected
  • Reason: Degrades I2P network performance without providing anonymity benefits
  • Affects: Only Tor exit nodes, not relays or regular Tor clients
  • Alternative: Use I2P or Tor separately, not combined

MD5 Digest Authentication

  • Status: Deprecated (use SHA-256)
  • Property: tunnel.N.option.proxy.auth.USER.md5
  • Reason: MD5 cryptographically broken
  • Replacement: tunnel.N.option.proxy.auth.USER.sha256 (since 0.9.56)
  • Timeline: MD5 still supported but discouraged

Configuration Architecture Changes

Monolithic Configuration Files (Version 0.9.42+)

  • Affected: clients.config, i2ptunnel.config
  • Status: Deprecated in favor of split directory structure
  • Migration: Automatic on first run after 0.9.42 upgrade
  • Compatibility: Legacy format still works (backward compatible)
  • Recommendation: Use split format for new configurations

Java Version Requirements

Java 6 Support

  • Ended: Version 0.9.23 (November 2015)
  • Minimum: Java 7 required since 0.9.23

Java 17 Requirement (Upcoming)

  • Status: CRITICAL UPCOMING CHANGE
  • Target: Next major release after 2.10.0 (likely 2.11.0 or 3.0.0)
  • Current Minimum: Java 8
  • Action Required: Prepare for Java 17 migration
  • Timeline: To be announced with release notes

Removed Features

BOB Protocol (Android)

  • Removed: Version 0.9.41
  • Platform: Android only
  • Alternative: SAM or I2CP protocols
  • Desktop: BOB still available on desktop platforms
  1. Authentication: Migrate from MD5 to SHA-256 digest authentication
  2. Configuration Format: Migrate to split directory structure for clients and tunnels
  3. Java Runtime: Plan for Java 17 upgrade before next major release
  4. Tor Integration: Do not route I2P through Tor exit nodes

References

Official Documentation

Source Code

Community Resources

API Documentation

Specification Status

  • Last Specification Update: January 2023 (Version 0.9.57)
  • Current I2P Version: 2.10.0 (September 2025)
  • Technical Accuracy: Specification remains accurate through 2.10.0 (no breaking changes)
  • Maintenance: Living document updated when configuration format modified

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