==============
The TINC HOWTO
==============
Wessel Dankers
wsl@nl.linux.org
Introduction
------------
Tinc is a system to create a virtual ethernet network on top of an existing
infrastructure. This infrastructure can be anything from modem lines to
gigabit ethernet networks, as long as they talk IP. Once you install and
configure tinc, your host will get an extra IP address, just like it would
when you stick an extra ethernet card into it. Using this IP address, it can
communicate with all hosts in its virtual network using strong encryption.
If you install Tinc on a router (and pick your numbers correctly) you can
have the router forward all packets. This way you can---instead of
connecting hosts---connect entire sites together! Now you need only one
outgoing network connection for both internet and intranet.
Architecture
------------
FIXME
Getting Tinc
------------
Before you fetch the latest tarball, you might want to check if there's a
package for your Linux distribution. One of the main authors is a Debian
Developer, so you can expect the Debian packages to be very up to date.
The official website for Tinc can be found at http://tinc.nl.linux.org/.
There you can find Debian packages, RPM's and of course... the tarball!
Since we run Doohickey Linux Pro 1.0, for which no package exists (or
indeed the distribution itself) we shall compile the package ourselves.
Building
--------
The Tinc source adheres to so many standards it makes you head spin.
Even the debug messages have been localized! Amazing. Tinc also comes
with a configuration script. If you like to see what is there to
configure run ./configure --help | more. If you don't have time for such
nonsense:
./configure --sysconfdir=/etc
This will see if your system is nice enough to run tinc on, and will
create some Makefiles and other stuff which will together build tinc.
make
make install
The first will do the actual build, the second copies all files into place.
The kernel
----------
FIXME
Picking your numbers
--------------------
The first thing we should do is pick network numbers. Tinc has a very
peculiar taste for network numbers, which is caused by the way it routes
traffic. However, it turns out to be really handy if you want to use
your tinc host as a router for a site.
The numbers have to be in a range that is not yet in use in your existing,
real network! In this example we will use numbers from the 192.168.0/16
range. This is standard CIDR notation for all IP addresses from 192.168.0.0
to 192.168.255.255. The /16 means that the first 16 bits form the network
part.
It is common practice for Tinc networks to use private (RFC 1918) addresses.
This is not necessary, but it would be a waste to use official addresses
for a private network!
In the example we will connect three machines: f00f, fdiv and hlt. We will
give each an address, but not just that, also a slice of our address space
to play with.
Host Real address Tinc network
---------------------------------------------------
f00f 126.202.37.20 192.168.1.1/24
fdiv 126.202.37.81 192.168.2.1/24
hlt 103.22.1.218 192.168.3.1/24
It is very important that none of the Tinc netmasks overlap! Note how the
192.168.0/16 network covers the entire address space of the three hosts.
We will refer to the 192.168.0/16 network as the `umbrella' from now on.
As you can see we can fit 256 hosts into this umbrella this way, which is
also the practical maximum for tinc.
The configuration file
----------------------
Let's create a configuration file for f00f. We have to put it in /etc/tinc,
unless you participate in multiple umbrella's (more on that later).
MyOwnVPNIP = 192.168.1.1/24
VpnMask = 255.255.0.0
ConnectTo = 126.202.37.81
ConnectTo = 103.22.1.218
The first two lines tell Tinc about the numbers we have chosen above.
Using the ConnectTo lines, the daemon will seek contact with the rest of
the umbrella. It's possible to configure any number of ConnectTo lines,
you can even omit them so that it just sits and waits until someone else
contacts it. Until someone does, the poor daemon won't be able to send
any data because it doesn't know where everybody is.
The passphrases
---------------
We will have to generate keys for ourselves, and get a key from everybody
we want to ConnectTo. All of these go into a directory named
/etc/tinc/passphrases. PROTECT THIS DIRECTORY!
mkdir -m 700 /etc/tinc/passphrases
To generate our own key:
genauth 1024 >/etc/tinc/passphrases/local
You should then proceed to give this key to anyone who wants to ConnectTo
you. DO THIS IN A SECURE MANNER! Anyone who has this number can do icky
things to the umbrella network! Encrypt it using PGP, GPG or another
program using asymetric keys. Read it over the phone (without anyone
listening of course). Send it by snailmail. Write the key down and bring
it to your partners yourself!
If you get any keys from your partners, store them under their network
number. For example, the key we get from fdiv's network administrator
will be stored in /etc/tinc/passphrases/192.168.2.0 (note the 0).
--
$Id: HOWTO,v 1.2.2.2 2000/06/30 21:16:52 wsl Exp $