Dependency

Java Runtime Version 7 or higher. (Oracle, OpenJDK, or IcedTea Java Version 7 or 8 recommended, except Raspberry Pi: Oracle JDK 8 for ARM, PowerPC: IBM Java SE 7 or 8)
Determine your installed Java version here or type java -version at your command prompt. Java 9 support is in development and it is not recommended for general use.

Release Notes

Clean installs

Windows
c8fed029d71b819afc129d6a397ea5983de3375ae2985d97661153405ffc0dde

Download that file and run it.

Mac OS X
dc26fb5c268dfe63b98bce66381c24c908f0b8265ddf731f4daf6fb82c4b7376

Download that file and double-click it (if that works) or type java -jar i2pinstall_0.9.31.jar in a terminal to run the installer. You may be able to right-click and select "Open with Java".

Command line (headless) install:

Download the 0.9.31 OSX graphical installer file above and run java -jar i2pinstall_0.9.31.jar -console from the command line.
Linux / BSD / Solaris
dc26fb5c268dfe63b98bce66381c24c908f0b8265ddf731f4daf6fb82c4b7376

Download that file and double-click it (if that works) or type java -jar i2pinstall_0.9.31.jar in a terminal to run the installer. On some platforms you may be able to right-click and select "Open with Java".

Command line (headless) install:

Download the graphical installer file above and run java -jar i2pinstall_0.9.31.jar -console from the command line.
Android
5871f4b8cfd02dd298bf4ebf84ab697579196e85a3e9163bf1c1f2118fa17386
Requires Android 2.3 (Gingerbread) or higher. If you earlier installed I2P, you need to reinstall because we have also changed the release keys. 512 MB RAM minimum; 1 GB recommended. The release and dev versions of the I2P APK are not compatible, as they are signed by zzz and str4d respectively. Uninstall one before installing the other.
Source package
94867fc8ac91eb561598736f6d51773375110db546f8b057c29758b0045931d8

Alternately, you can fetch the source from monotone or via Git from git.repo.i2p or Github.
Run (tar xjvf i2psource_0.9.31.tar.bz2 ; cd i2p-0.9.31 ; ant pkg) then either run the GUI installer or headless install as above.

Android source is in monotone and on Github. Android builds require the I2P source. See the documentation in the Android source for additional build requirements and instructions.

The files are signed by zzz, whose key is here.

Post-install work

After running the installer on windows, simply click on the "Start I2P" button which will bring up the router console, which has further instructions.

On Unix-like systems, I2P can be started as a service using the "i2prouter" script, located in the directory you selected for I2P. Changing to that directory in a console and issuing "sh i2prouter status" should tell you the router's status. The arguments "start", "stop" and "restart" control the service. The router console can be accessed at its usual location. For users on OpenSolaris and other systems for which the wrapper (i2psvc) is not supported, start the router with "sh runplain.sh" instead.

When installing for the first time, please remember to adjust your NAT/firewall if you can, bearing in mind the Internet-facing ports I2P uses, described here among other ports. If you have successfully opened your port to inbound TCP, also enable inbound TCP on the configuration page.

Also, please review and adjust the bandwidth settings on the configuration page, as the default settings of 96 KBps down / 40 KBps up are fairly slow.

If you want to reach eepsites via your browser, have a look on the browser proxy setup page for an easy howto.

Updates from earlier releases:

Both automatic and manual upgrades are available for the release.

Automatic updates

If you are running 0.7.5 or later, your router should detect the new release. To upgrade simply click the 'Download Update' button on your router console when it appears.

Since 0.9.23, some releases are signed by str4d, whose signing key has been in the router since 0.9.9. Routers older than 0.9.9 will fail to verify update files signed by str4d, and will need to be manually updated using the process below.

Manual updates
a32ffb5f76aaa8bdc86854d741a32dc384e5e0b5ee00c6feec6fa3838467d1c4
  1. Download that file to your I2P installation directory and rename as i2pupdate.zip. (alternately, you can get the source as above and run "ant updater", then copy the resulting i2pupdate.zip to your I2P installation directory). You do NOT need to unzip that file.
  2. Click "Restart"
  3. Grab a cup of coffee and come back in 11 minutes
The file is signed by zzz, whose key is here.

Previous Releases

Previous releases are available on Google Code and Launchpad and within the I2P network on echelon.i2p.xyz.