n2n/doc/Building.md

This document describes the process for compiling n2n in several different scenarios.

There are some configuration options available during the build process, which are documented in the Build time Configuration page.

Also of use are the steps used for the automated Continuous Integration process, which can be found in the Github actions config file

Git submodules

If you are compiling with the UPnP libraries, it is possible that your operating system or your build system do not include binaries for the required libraries.

Using these libraries can cause issues with some build systems, so be aware that not all combinations are supportable.

To make this scenario simpler, the required source code has been added to this repository as git submodules which require one extra step to complete their checkout.

So the very first time after cloning the n2n git repo, you should run this command in the n2n directory to fetch the submodules:

git submodule update --init --recursive

Build on macOS

In order to use n2n on macOS, you first need to install support for TUN/TAP interfaces:

brew tap homebrew/cask
brew cask install tuntap

If you are on a modern version of macOS (i.e. Catalina), the commands above will ask you to enable the TUN/TAP kernel extension in System Preferences → Security & Privacy → General.

For more information refer to vendor documentation or the Apple Technical Note.

Note that on the newest MacOS versions and on Apple Silicon, there may be increasing security restrictions in the OS that make installing the TUN/TAP kernel extension difficult. Alternative software implementations to avoid these difficulties are being discussed for future n2n versions.

Build on Windows

The following document one possible windows compile recipe. The reason a MinGW build process is used is it is more friendly to open source development.

MinGW

These steps were tested on a fresh install of Windows 10 Pro with all patches applied as of 2021-09-29.

• Install Chocolatey (Following instructions on https://chocolatey.org/install)
• from an admin cmd prompt
  • choco install git mingw make
• Once the git package is installed, you will have a new start menu item called "Git Bash". All the remaining commands must be run from inside the shell started by that menu item:
  • git clone $THIS_REPO
  • cd n2n
  • ./scripts/hack_fakeautoconf.sh
  • make
  • make test

Due to limitations in the Windows environment, the normal autotools steps have been emulated by the hack_fakeautoconf - This currently results in the version number reported by the compiled software being inaccurate.

Note: MinGW builds have had a history of incompatibility reports with other OS builds (for example #617 and #642) However, if the tests pass, you should have a high confidence that your build will be compatible.

Run on Windows

In order to run n2n on Windows, you will need the following:

• The TAP drivers should be installed into the system. They can be installed from http://build.openvpn.net/downloads/releases, search for "tap-windows".

• If OpenSSL has been linked dynamically, the corresponding .dll file should be available onto the target computer.

The edge.exe program reads the edge.conf file located into the current directory if no option is provided.

The supernode.exe program reads the supernode.conf file located into the current directory if no option is provided.

Example edge.conf and supernode.conf are available.

See edge.exe --help and supernode.exe --help for a full list of supported options.

Cross compiling on Linux

Using the Makefiles and Autoconf

The Makefiles are all setup to allow cross compiling of this code. You will need to have the cross compiler, binutils and any additional libraries desired installed for the target architecture. Then you can run the ./configure with the appropriate CC and AR environment and the right --host option.

If compiling on Debian or Ubuntu, this can be as simple as the following example:

HOST_TRIPLET=arm-linux-gnueabi
sudo apt-get install binutils-$HOST_TRIPLET gcc-$HOST_TRIPLET
./autogen.sh
export CC=$HOST_TRIPLET-gcc
export AR=$HOST_TRIPLET-ar
./configure --host $HOST_TRIPLET
make

A good starting point to determine the host triplet for your destination platform can be found by copying the ./config.guess script to it and running it on the destination.

This is not a good way to produce binaries for embedded environments (like OpenWRT) as they will often use a different libc environment.

N2N Packages

There are also some example package build recipes included with the source.

• Debian
• RPM
• OpenWRT