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QUICKSTART.md

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Creating a new VPN

If you are just starting to create a VPN, first consider what IP addresses you want to use on the VPN. There are several blocks of IP addresses reserved for private networks:

  • 192.168.0.0/16
  • 172.16.0.0/12
  • 10.0.0.0/8
  • fd00::/8

Make sure the IP range you are choosing is large enough for all the nodes you want to add to the VPN, and also consider that some of these private address ranges might also be used on local area networks, so check in advance that you won't conflict with any range that is already in use by any of the participants. When in doubt, just pick one and try it out. For this quickstart guide, we will use 172.16.0.0/16 as the range of the VPN.

Also think of a name for your whole VPN. This will be used as the "netname" parameter for tinc, and on Linux this will then also automatically be used as the name for the virtual network interface. We will use "myvpn" as the name in the examples below.

Create your first node

Think of a name for your first node. We will call it "first" in the examples below. The name must be unique for each node in the same VPN, and may only contain letters, numbers and underscores. Apart from that you can choose whatever you want. Now we can create the first node:

sudo tinc -n myvpn init first

This creates the initial configuration for the node, but has not started tinc yet. Before we do that, two things have to be done first. We have to tell tinc which part of the IP range of the VPN belongs to this particular node. We will use 172.168.1.0/24 for this example. We then have to give this command:

sudo tinc -n myvpn add Subnet 172.168.1.0/24

However, tinc itself will not actually configure the virtual network interface for you. You have to create a script named tinc-up that does this. To do this, run the command:

sudo tinc -n myvpn edit tinc-up

This should start an editor. When you ran the init command, a dummy script was already created. Edit it to make sure it looks like this:

#!/bin/sh
ifconfig $INTERFACE 172.168.1.1/16

Note that the literal text $INTERFACE should be in the script, tinc will make sure that environment variable is set correctly when the script is run. The address should be that of the node itself, but the netmask or prefix length (the /16 in this case) you provide must be that of the whole VPN. This tells the kernel that everything for the VPN's IP range should go to tinc's virtual network interface, from then on tinc will handle it and route it to the right node based on the Subnets that you configured.

To start tinc run:

sudo tinc -n myvpn start

This will start running tinc in the background. You can also run it in the foreground with debugging enabled using this command:

sudo tinc -n myvpn start -d5 -D

This might be helpful in the beginning to debug any issues you have setting up the VPN.

Create your second node

There are two ways to add new nodes to the VPN.

Using import/export of host config files

One way to do it is to create a second node just like you created the first node. Just make sure it has a different name (let's call it "second"), and that it gets a different IP range for itself (let's use 172.168.2.0/24). So on the second node run:

sudo tinc -n myvpn init second
sudo tinc -n myvpn add Subnet 172.168.2.0/24
sudo tinc -n myvpn edit tinc-up

And make sure the second node's tinc up contains:

#!/bin/sh
ifconfig $INTERFACE 172.168.2.1/16

And start the second node. After you have done that, you have to make sure that the two nodes can find each other. To do this, at least one node should have a public IP address. Let's assume the first node has public IP address 93.184.216.34. You would then give this command on the first node:

sudo tinc -n myvpn add Address 93.184.216.34

Note that if you have a public domain name, you can also use that domain name instead of a numeric IP address. Now run the following on the first node:

sudo tinc -n myvpn export

This outputs a small amount of text that contains the node's public keys and the public address. On the second node, run this:

sudo tinc -n myvpn import

And copy&paste the output from the first node, then press ctrl-D on a new line. If done correctly it should tell you that it has imported the host configuration file. Now you have to do the same but in the other direction: use the export command on the second node, and then use import on the first node. Now that both nodes know each other, they should be able to connect. This should happen automatically after a while.

Note that instead of copy&pasting the text manually, you could also redirect it to a text file, send it via email, pipe it through an SSH connection, or use any other way to exchange the host config files. For more information, see the manual.

Using invitations

Another way to add more nodes is to have an existing node generate an invitation for another node. A prerequisite is that the node generating the invitation should have a public IP address to the invitee will be able to connect to it. Again, let's assume the first node has public IP address 93.184.216.34:

sudo tinc -n myvpn add Address 93.184.216.34

Then on the first node, generate in invitation for the second node:

sudo tinc -n myvpn invite second

This should generate one line of text that looks like an URL, like for example:

93.184.216.34:655/R4BU9VMzdY4S_EIuAhW1-B0XV50HqooyEv6EUfl4k6Z9_zrq

On the second node, don't using init to create the initial configuration. Instead, run the following command:

sudo tinc -n myvpn join 93.184.216.34:655/R4BU9VMzdY4S_EIuAhW1-B0XV50HqooyEv6EUfl4k6Z9_zrq

It will then initialize itself and make a connection to the first node and exchange configuration files automatically. You still have to add the Subnet and edit tinc-up afterwards on the second node (as described in the section above), and use the start command to start tinc.

Invitations are easier to use, and relatively secure. Once used, the invitation is no longer valid. However, be aware that anyone holding an unused invitation can use it to join a VPN, so make sure you do not make invitation URLs public.

Checking that things are working

After you have set up two nodes, you should be able to ping 172.16.1.1. If it doesn't work, there can be multiple reasons. Make sure you don't have any firewall rules blocking tinc's port, and that at least one node has a public IP address that is accepting incoming connections. You can further investigate by asking tinc the status of a given node. So for example, on the first node, you can run:

sudo tinc -n myvpn info second

You can also dump a list of connections:

sudo tinc -n myvpn dump connections

Or dump nodes to get a list of known nodes, dump subnets to see all subnets. If you ran tinc in the background, you can get still get log output like so:

sudo tinc -n myvpn log 5

Finally, if the problem is not with tinc, using tcpdump to look at the traffic on your real and virtual interfaces might help determine what the problem is.