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cjdns: cjd's Network Suite

Dear Reader,

I suppose you are here because you are interested in alternative networks, perhaps for censorship resistance, perhaps network security and I have no doubt you are wondering what the hell this thing is supposed to do.

We can all find common ground in the statement that The Internet is painfully insecure. Free speech and privacy advocates find it insecure against government listening and blocking, governments find it insecure against hackers taking systems over and leaking secrets, and internet service providers find it insecure against DDoS kiddies who use large swarms of zombie machines to send enough traffic to overload a network link. These are, however, all different views of the same problem.

We have a number of somewhat competing offerings to solve this problem from ISPs and government. We have IPSEC, DNSSEC, numerous proposals from the mundane to the wild and whacky such as "internet drivers licenses".

The people who have developed these proposals are unfortunately limited in their thinking. ISPs are unable to see past the now almost 30 year old routing protocols which glue together the internet of today. Government actors are conditioned to think of something as secure when they have control over it. A quick look at x509 (the authentication system behind SSL) shows us that central points of failure inevitably live up to their name. In order to have a central authority, the people must not only be able to trust his motives but they must be able to trust his system's integrity as well. Recently people's e-mail was compromised when DigiNotar certificate authority was hacked and used to forge gmail certificates.

It is worthy of note that the vulnerability in DNS which ICE exploited to take down websites they deemed "dedicated to copyright infringement" was also used by Anonymous to replace a movie industry website with a manifesto.

A System Is Only Secure When Nobody Has Total Control

What is cjdns?

It is a routing engine designed for security, scalability, speed and ease of use. The dream: You type ./cjdroute and give it an interface which connects another node and it gives you an ipv6 address generated from a public encryption key and a virtual network card (TUN device) which you can use to send packets to anyone in the cjdns network to which you are connected.

How does it work?

In order to understand how cjdns works, it is important to understand how the existing internet works when you send a packet, at each "intersection in the road" the router reads the address on the packet and decides which turn it should take. In the cjdns net, a packet goes to a router and the router labels the packet with directions to a router which will be able to best handle it. That is, a router which is near by in physical space and has an address which is numerically close to the destination address of the packet. The directions which are added to the packet allow it to go through a number of routers without much handling, they just read the label and bounce the packet wherever the next bits in the label tell them to. Routers have a responsibility to "keep in touch" with other routers that are numerically close to their address and also routers which are physically close to them.

The router engine is a modified implementation of the Kademlia DHT design.

How close is it to complete?

A live testing network exists with at least 50 active nodes. The software has been tested and runs on x86, amd64, ARMv5 and PowerPC64 (ps3). It has run well on every type of Linux that it has been installed on.

17:44 < Hyper> Mac user here: Just wanted to let you guys know that that commit did indeed make it so I could build cjdns. Thanky!

What about DNS?

DNS is a complex system to implement and highly complex to implement without central authority, if you would like to offer help with this part, I invite you to come join.

Further Reading & Discussion

Please read the Whitepaper, or at least skim it:

If you are still interested in this project and want to follow it, get in the channel on IRC:

Some raw pastes for the curious:

Thank you for your time and interest, Caleb James DeLisle == cjdelisle == cjd

Possibly outdated below.
Please check IRC for the latest info.


How to compile cjdns:

  • Hint 1: You did a backup recently. ;)
  • Hint 2: Created on Debian Squeeze, will work on Ubuntu/Mint just as well.
  • Hint 3: By default the build process will try to find Libevent2 in your operating system and if it can't be found, default to compiling and static linking it's own. If you want to force it to use dynamic or static linking, see [Non-Standard Setups] below.

0: Install the build tools you will need.

# apt-get install cmake git build-essential

1: Retrieve cjdns from GitHub.

Grab it from GitHub and change to the source directory:

# git clone cjdns
# cd cjdns

2: Setup environment.

Setup build directory and change to it:

# mkdir build
# cd build

You Likely want DEBUG logs (this is VERY ALPHA after all), so set the Log_LEVEL environment variable:

# export Log_LEVEL=DEBUG

3: Build.

Pre-build step with cmake:

# cmake ..

Build cjbdns:

# make

Look for:

[100%] Built target LabelSplicer_test

ALL DONE! Wanna test? Sure.

# make test


Use screen or such to get a few ttys, Xterms, pipe to log and bg, whatever.

Change to the cjdns/build directory if you need to.

Run cjdroute without options for HELP:

# ./cjdroute

0: Make sure you've got the stuff.

# sudo modprobe tun

If it says nothing, good.

If it says: FATAL: Module tun not found. Bad.

In this case, look up how to get the tun module installed for your platform. How to get TUN working is beyond the scope of this document, look up how to install openvpn on your particular platform.

NOTE: TonidoPlug2 ships with a kernel which does not include TUN and does not offer the source code to build it yourself.

# cat /dev/net/tun

If it says: cat: /dev/net/tun: File descriptor in bad state Good!

If it says: cat: /dev/net/tun: No such file or directory

Create it using:

# mkdir /dev/net ; mknod /dev/net/tun c 10 200 ; chmod 0666 /dev/net/tun

Then cat /dev/net/tun again.

1: Generate a new configuration file.

# ./cjdroute --genconf >> cjdroute.conf

2: Find a friend.

In order to get into the network you need to meet someone who is also in the network and connect to them. This is required for a number of reasons:

  1. It is a preventitive against abuse because bad people will be less likely to abuse a system after they were, in an act of human kindness, given access to that system.
  2. This is not intended to overlay The Old Internet, it is intended to replace it. Each connection will in due time be replaced by a wire, a fiber optic cable, or a wireless network connection.
  3. In any case of a disagreement, there will be a "chain of friends" linking the people involved so there will already be a basis for coming to a resolution.

tl;dr Get out and make some human contact once in a while!

You can meet people to peer with in the IRC channel:

NOTE: If you're just interested in setting up a local VPN between your computers, this step is not necessary.

3: Fill in your friend's info.

In your cjdroute.conf file, you will see:

        // Nodes to connect to.
            // Add connection credentials here to join the network
            // Ask somebody who is already connected.

After adding their connection credentials, it will look like:

        // Nodes to connect to.
                "password": "thisIsNotARealConnection",
                "authType": 1,
                "publicKey": "thisIsJustForAnExampleDoNotUseThisInYourConfFile.k",
                "trust": 10000

You can add as many connections as you want to your "connectTo" section.

Your own connection credentials will be shown in a JSON comment above in your "authorizedPasswords" section. Do not modify this but if you want to allow someone to connect to you, give it to them.

It looks like this:

    /* These are your connection credentials
       for people connecting to you with your default password.
       adding more passwords for different users is advisable
       so that leaks can be isolated.

            "password": "thisIsNotARealConnectionEither",
            "authType": 1,
            "publicKey": "thisIsAlsoJustForAnExampleDoNotUseThisInYourConfFile.k",
            "trust": 10000
    */ is to be replaced with the IPv4 address which people will use to connect to you from over The Old Internet.

4: Start it up!

sudo su -c "./cjdroute < cjdroute.conf >> cjdroute.log & ./cjdroute --getcmds < cjdroute.conf | bash"

5: Get in IRC

Welcome to the network, you are now a real network administrator. There are responsibilities which come with being a network administrator which include being available in case there is something wrong with your equipment. You can connect to irc via or you can connect to irc inside of the network by going to fcec:cbd:3c03:1a2a:63f:c917:b1db:1695 or fce4:d261:d2d8:68df:c67d:11be:6cf6:3e09 Either way, the channel to join is #cjdns and you should stay there so that we are able to reach you if something goes wrong.


This starts cjdroute as the root user so cjdroute can configure your system and shed permissions. If you really want to start cjdroute as a non-root user, see Non-Standard Setups below.

Protect your conf file! A lost conf file means you lost your password and connections and anyone who connected to you will nolonger be able to connect. A compromized conf file means that other people can impersonate you on the network.

chmod 400 cjdroute.conf
mkdir /etc/cjdns ; cp ./cjdroute.conf /etc/cjdns/

Known Issues

Old versions of the IP utility do not work for creating tunnel devices.

# ip -V
ip utility, iproute2-ss080725
# /sbin/ip tuntap add mode tun user cjdns
Object "tuntap" is unknown, try "ip help".

# /sbin/ip tuntap list
Object "tuntap" is unknown, try "ip help".

# ip -V
ip utility, iproute2-ss100519
# /sbin/ip tuntap list
tun0: tun user 1001

The fix: for now grab a copy of a newer ip binary and copy it to your home directory. Replacing the system binaries is not likely a good idea.

Currently we are still debugging some routing issues.

If you want to help out, load up a few VMs or physical boxen, link them, see what happens, tell us! :)

Lots of bugs to fix yet, but hey, it's talking now!

Self-Check Your Network

Once your node is running, you're now a newly minted IPv6 host. Your operating system may automatically reconfigure network services to use this new address. If this is not what you intend, you should check to see that you are not offering more services then you intended to. ;)

1: Obtain IP address.

Use ifconfig -a to find your TUN device's IPv6 address. (Same as above.)

2: Scan for open services.

Run nmap to discover which services are accessible from this address. For example, to scan the address fcf7:75f0:82e3:327c:7112:b9ab:d1f9:bbbe:

# nmap -6 -n -r -v -p1-65535 -sT fcf7:75f0:82e3:327c:7112:b9ab:d1f9:bbbe

Starting Nmap 5.61TEST2 ( ) at 2011-12-29 20:40 EST
Initiating Connect Scan at 20:40
Scanning fcf7:75f0:82e3:327c:7112:b9ab:d1f9:bbbe [65535 ports]
Completed Connect Scan at 20:40, 4.38s elapsed (65535 total ports)
Nmap scan report for fcf7:75f0:82e3:327c:7112:b9ab:d1f9:bbbe
Host is up (0.00073s latency).
All 65535 scanned ports on fcf7:75f0:82e3:327c:7112:b9ab:d1f9:bbbe are closed

Read data files from: /usr/local/bin/../share/nmap
Nmap done: 1 IP address (1 host up) scanned in 4.60 seconds
    Raw packets sent: 0 (0B) | Rcvd: 0 (0B)

3: If you see anything open, fix it.

Examples for SSH and Samba are below.


Edit /etc/ssh/sshd_config:


^ Replace in the example above with your STATIC IP (or map DHCP via MAC).


Edit /etc/samba/smb.conf:

interfaces = eth0
bind interfaces only = Yes

^ This will cause Samba to not bind to tun0 (or whichever TUN device you are using).

Thats it for now! Got More? Tell us on IRC.

Non-Standard Setups

Instructions for building or installing in non-default ways.

Dynamically linking to Libevent2

By default, the build process will search your system for Libevent2 and if it is not found, it will download, compile, and statically link it. If you would like to link it dynamically follow these instructions.

1: Remove older versions of dependencies: libevent and libevent-dev.

Be sure libevent is gone and remove if found. It will cause problems during the build.

Check to see which libevent is installed:

# dpkg -l | grep ^ii| grep libevent
ii  libevent-dev            1.3e-3     Development libraries, header files and docs
ii  libevent1               1.3e-3     An asynchronous event notification library
# apt-get remove libevent-dev

Note: You may need to (re)compile TOR if you use it.

2: Obtain latest libevent2 dependency manually.

CHECK for LATEST version. (This document assumes 2.0.16.)

Grab the stable tarball from libevent and untar:

# wget
# tar -xzf libevent-2.0.16-stable.tar.gz

Enter directory and compile libevent:

# cd libevent-2.0.16-stable
# ./configure

Resolve missing dependencies if needed and run again until all errors gone:

# make
# make install

3: Compile cjdns using NO_STATIC.

By compiling with NO_STATIC, the process will fail rather than defaulting to static link.

# NO_STATIC=1 cmake ..
# make

You can also force a static build even if you have libevent2 by using:

# STATIC=1 cmake ..
# make

Start cjdroute as non-root user.

If you're using an OpenVZ based VPS then you will need to use this as OpenVZ does not permit persistent tunnels.

Create a cjdns user:

# useradd cjdns

Create a new TUN device and give the cjdns user authority to access it:

# /sbin/ip tuntap add mode tun user cjdns
# /sbin/ip tuntap list | grep `id -u cjdns`

The output of the last command will tell you the name of the new device. If that name is not "tun0" then you will need to edit the cjdroute.conf file and change the line which says: "tunDevice": "tun0" to whatever it is.

4b-1: Get commands.

Get the commands to run in order to prepare your TUN device by running:

# ./cjdroute --getcmds < cjdroute.conf

These commands should be executed as root now every time the system restarts.

4b-2: Fire it up!

# sudo -u cjdns ./cjdroute < cjdroute.conf

To delete a tunnel, use this command:

# /sbin/ip tuntap del mode tun <name of tunnel>

Created on 2011-02-16.

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