n3n is a light VPN software which makes it easy to create virtual networks bypassing intermediate firewalls.

In order to start using n3n, two elements are required:

• A supernode: it allows edge nodes to announce and discover other nodes. It must have a port publicly accessible on internet.
• edge nodes: the nodes which will be a part of the virtual networks

A virtual network shared between multiple edge nodes in n3n is called a community. A single supernode can relay multiple communities and a single computer can be part of multiple communities at the same time. An encryption key can be used by the edge nodes to encrypt the packets within their community.

n3n tries to establish a direct peer-to-peer connection via udp between the edge nodes when possible. When this is not possible (usually due to special NAT devices), the supernode is also used to relay the packets.

n3n was originally based on an older n2n project and hopes to keep protocol compatiblilty with that.

• Any new self-contained tools or modules are licensed GPL-2.0-only.
• Existing code is licensed GPL-3-only.
• There are multiple distinct copyright holders throughout the codebase.
• There is no Contributor Licence Agreement and thus there is no single body that can take ownership of the code and/or change the licensing.

Beward that while Debian (and those based on it) Linux distributions do appear to provide n2n as a package, it is based on an antique version and is not compatible with this.

Alternatively, up-to-date packages for most distributions are available as part of the latest release.

On host1 run:

$ sudo edge -c mynetwork -k mysecretpass -a 192.168.100.1 -f -l supernode.ntop.org:7777 start

On host2 run:

$ sudo edge -c mynetwork -k mysecretpass -a 192.168.100.2 -f -l supernode.ntop.org:7777 start

Now the two hosts can ping each other.

IMPORTANT It is strongly advised to choose a custom community name (-c) and a secret encryption key (-k) in order to prevent other users from connecting to your computer. For the privacy of your data sent and to reduce the server load of supernode.ntop.org, it is also suggested to set up a custom supernode as explained below.

You can create your own infrastructure by setting up a supernode on a public server (e.g. a VPS). You just need to open a single port (1234 in the example below) on your firewall (usually iptables).

1. Install the n3n package
2. Edit /etc/n3n/supernode.conf and add the following:

   -p=1234
   

3. Start the supernode service with sudo systemctl start supernode
4. Optionally enable supernode start on boot: sudo systemctl enable supernode

Now the supernode service should be up and running on port 1234. On your edge nodes you can now specify -l your_supernode_ip:1234 to use it. All the edge nodes must use the same supernode.

On Linux, compilation from source is straight forward:

./autogen.sh
./configure
make

# optionally install
make install

For Windows, MacOS, optimizations and general building options, please check out Building documentation for compilation and running.

IMPORTANT It is generally recommended to use the latest stable release. Please note that the current main branch usually is not guaranteed to be backward compatible neither with the latest stable release nor with previous main states. On the other hand, if you dare to try bleeding edge features, you are encouraged to compile from main – just keep track of sometimes rapidly occuring changes. Feedback in the Issues section is appreciated.

When payload encryption is enabled (provide a key using -k), the supernode will not be able to decrypt the traffic exchanged between two edge nodes but it will know that edge A is talking with edge B.

The choice of encryption schemes that can be applied to payload has recently been enhanced. Please have a look at Crypto description for a quick comparison chart to help make a choice. n2n edge nodes use AES encryption by default. Other ciphers can be chosen using the -A_ option.

A benchmark of the encryption methods is available when compiled from source with tools/n2n-benchmark.

The header which contains some metadata like the virtual MAC address of the edge nodes, their IP address, their real hostname and the community name optionally can be encrypted applying the community.header_encryption=true option to the edges.

More information about communities, support for multiple supernodes, routing, traffic restrictions and on how to run an edge as a service is available in the more detailed documentation.

You can contribute to n2n in various ways:

• Update an open issue or create a new one with detailed information
• Propose new features
• Improve the documentation
• Provide pull requests with enhancements

For details about the internals of n2n check out the Hacking guide.

Answers to frequently asked questions can be found in our FAQ document.

(C) 2007-22 - ntop.org and contributors Copyright (C) 2023-24 Hamish Coleman