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This is tinc.info, produced by makeinfo version 4.1 from tinc.texi.
INFO-DIR-SECTION Networking tools
START-INFO-DIR-ENTRY
* tinc: (tinc). The tinc Manual.
END-INFO-DIR-ENTRY
This is the info manual for tinc, a Virtual Private Network daemon.
Copyright (C) 1998-2002 Ivo Timmermans <itimmermans@bigfoot.com>,
Guus Sliepen <guus@sliepen.warande.net> and Wessel Dankers
<wsl@nl.linux.org>.
$Id: tinc.texi,v 1.8.4.28 2002/04/09 11:43:29 guus Exp $
Permission is granted to make and distribute verbatim copies of this
manual provided the copyright notice and this permission notice are
preserved on all copies.
Permission is granted to copy and distribute modified versions of
this manual under the conditions for verbatim copying, provided that the
entire resulting derived work is distributed under the terms of a
permission notice identical to this one.

File: tinc.info, Node: Top, Next: Introduction, Prev: (dir), Up: (dir)
* Menu:
* Introduction:: Introduction
* Preparations::
* Installation::
* Configuration::
* Running tinc::
* Technical information::
* About us::
* Concept Index:: All used terms explained

File: tinc.info, Node: Introduction, Next: Preparations, Prev: Top, Up: Top
Introduction
************
tinc is a Virtual Private Network (VPN) daemon that uses tunneling
and encryption to create a secure private network between hosts on the
Internet.
Because the tunnel appears to the IP level network code as a normal
network device, there is no need to adapt any existing software. The
encrypted tunnels allows VPN sites to share information with each other
over the Internet without exposing any information to others.
This document is the manual for tinc. Included are chapters on how
to configure your computer to use tinc, as well as the configuration
process of tinc itself.
* Menu:
* VPNs:: Virtual Private Networks in general
* tinc:: about tinc
* Supported platforms::

File: tinc.info, Node: VPNs, Next: tinc, Prev: Introduction, Up: Introduction
Virtual Private Networks
========================
A Virtual Private Network or VPN is a network that can only be
accessed by a few elected computers that participate. This goal is
achievable in more than just one way.
Private networks can consist of a single stand-alone Ethernet LAN.
Or even two computers hooked up using a null-modem cable. In these
cases, it is obvious that the network is _private_, no one can access
it from the outside. But if your computers are linked to the Internet,
the network is not private anymore, unless one uses firewalls to block
all private traffic. But then, there is no way to send private data to
trusted computers on the other end of the Internet.
This problem can be solved by using _virtual_ networks. Virtual
networks can live on top of other networks, but they use encapsulation
to keep using their private address space so they do not interfere with
the Internet. Mostly, virtual networks appear like a singe LAN, even
though they can span the entire world. But virtual networks can't be
secured by using firewalls, because the traffic that flows through it
has to go through the Internet, where other people can look at it.
As is the case with either type of VPN, anybody could eavesdrop. Or
worse, alter data. Hence it's probably advisable to encrypt the data
that flows over the network.
When one introduces encryption, we can form a true VPN. Other
people may see encrypted traffic, but if they don't know how to
decipher it (they need to know the key for that), they cannot read the
information that flows through the VPN. This is what tinc was made for.

File: tinc.info, Node: tinc, Next: Supported platforms, Prev: VPNs, Up: Introduction
tinc
====
I really don't quite remember what got us started, but it must have
been Guus' idea. He wrote a simple implementation (about 50 lines of
C) that used the ethertap device that Linux knows of since somewhere
about kernel 2.1.60. It didn't work immediately and he improved it a
bit. At this stage, the project was still simply called `vpnd'.
Since then, a lot has changed--to say the least.
tinc now supports encryption, it consists of a single daemon (tincd)
for both the receiving and sending end, it has become largely
runtime-configurable--in short, it has become a full-fledged
professional package.
tinc also allows more than two sites to connect to eachother and
form a single VPN. Traditionally VPNs are created by making tunnels,
which only have two endpoints. Larger VPNs with more sites are created
by adding more tunnels. tinc takes another approach: only endpoints
are specified, the software itself will take care of creating the
tunnels. This allows for easier configuration and improved scalability.
A lot can--and will be--changed. We have a number of things that we
would like to see in the future releases of tinc. Not everything will
be available in the near future. Our first objective is to make tinc
work perfectly as it stands, and then add more advanced features.
Meanwhile, we're always open-minded towards new ideas. And we're
available too.

File: tinc.info, Node: Supported platforms, Prev: tinc, Up: Introduction
Supported platforms
===================
tinc has been verified to work under Linux, FreeBSD, OpenBSD and
Solaris, with various hardware architectures. These are some of the
platforms that are supported by the universal tun/tap device driver or
other virtual network device drivers. Without such a driver, tinc will
most likely compile and run, but it will not be able to send or receive
data packets.
For an up to date list of supported platforms, please check the list
on our website: `http://tinc.nl.linux.org/platforms.html'.
Linux
-----
tinc was first written for Linux running on an intel x86 processor,
so this is the best supported platform. The protocol however, and
actually anything about tinc, has been rewritten to support random byte
ordering and arbitrary word length. So in theory it should run on other
processors that Linux runs on. It has already been verified to run on
alpha and sparc processors as well.
tinc uses the ethertap device or the universal tun/tap driver. The
former is provided in the standard kernel from version 2.1.60 up to
2.3.x, but has been replaced in favour of the tun/tap driver in kernel
versions 2.4.0 and later.
FreeBSD
-------
tinc on FreeBSD relies on the universal tun/tap driver for its data
acquisition from the kernel. Therefore, tinc will work on the same
platforms as this driver. These are: FreeBSD 3.x, 4.x, 5.x.
OpenBSD
-------
tinc on OpenBSD relies on the tun driver for its data acquisition
from the kernel. It has been verified to work under at least OpenBSD
2.9.
Tunneling IPv6 packets may not work on OpenBSD.
Solaris
-------
tinc on Solaris relies on the universal tun/tap driver for its data
acquisition from the kernel. Therefore, tinc will work on the same
platforms as this driver. These are: Solaris 8 (SunOS 5.8).
IPv6 packets cannot be tunneled on Solaris.

File: tinc.info, Node: Preparations, Next: Installation, Prev: Introduction, Up: Top
Preparations
************
This chapter contains information on how to prepare your system to
support tinc.
* Menu:
* Configuring the kernel::
* Libraries::

File: tinc.info, Node: Configuring the kernel, Next: Libraries, Prev: Preparations, Up: Preparations
Configuring the kernel
======================
If you are running Linux, chances are good that your kernel already
supports all the devices that tinc needs for proper operation. For
example, the standard kernel from Redhat Linux already has support for
ethertap and netlink compiled in. Debian users can use the modconf
utility to select the modules. If your Linux distribution supports
this method of selecting devices, look out for something called
`ethertap', and `netlink_dev' if it is using a kernel version prior to
2.4.0. In that case you will need both these devices. If you are using
kernel 2.4.0 or later, you need to select `tun'.
If you can install these devices in a similar manner, you may skip
this section. Otherwise, you will have to recompile the kernel in
order to turn on the required features. If you are unfamiliar with the
process of configuring and compiling a new kernel, you should read the
Kernel HOWTO (http://howto.linuxberg.com/LDP/HOWTO/Kernel-HOWTO.html)
first.
* Menu:
* Configuration of Linux kernels 2.1.60 up to 2.4.0::
* Configuration of Linux kernels 2.4.0 and higher::
* Configuration of FreeBSD kernels::
* Configuration of OpenBSD kernels::
* Configuration of Solaris kernels::

File: tinc.info, Node: Configuration of Linux kernels 2.1.60 up to 2.4.0, Next: Configuration of Linux kernels 2.4.0 and higher, Prev: Configuring the kernel, Up: Configuring the kernel
Configuration of Linux kernels 2.1.60 up to 2.4.0
-------------------------------------------------
Here are the options you have to turn on when configuring a new
kernel:
Code maturity level options
[*] Prompt for development and/or incomplete code/drivers
Networking options
[*] Kernel/User netlink socket
<M> Netlink device emulation
Network device support
<M> Ethertap network tap
If you want to run more than one instance of tinc or other programs
that use the ethertap, you have to compile the ethertap driver as a
module, otherwise you can also choose to compile it directly into the
kernel.
If you decide to build any of these as dynamic kernel modules, it's
a good idea to add these lines to `/etc/modules.conf':
alias char-major-36 netlink_dev
alias tap0 ethertap
options tap0 -o tap0 unit=0
alias tap1 ethertap
options tap1 -o tap1 unit=1
...
alias tap_N_ ethertap
options tap_N_ -o tap_N_ unit=_N_
Add as much alias/options lines as necessary.

File: tinc.info, Node: Configuration of Linux kernels 2.4.0 and higher, Next: Configuration of FreeBSD kernels, Prev: Configuration of Linux kernels 2.1.60 up to 2.4.0, Up: Configuring the kernel
Configuration of Linux kernels 2.4.0 and higher
-----------------------------------------------
Here are the options you have to turn on when configuring a new
kernel:
Code maturity level options
[*] Prompt for development and/or incomplete code/drivers
Network device support
<M> Universal tun/tap device driver support
It's not necessary to compile this driver as a module, even if you
are going to run more than one instance of tinc.
If you have an early 2.4 kernel, you can choose both the tun/tap
driver and the `Ethertap network tap' device. This latter is marked
obsolete, and chances are that it won't even function correctly
anymore. Make sure you select the universal tun/tap driver.
If you decide to build the tun/tap driver as a kernel module, add
these lines to `/etc/modules.conf':
alias char-major-10-200 tun

File: tinc.info, Node: Configuration of FreeBSD kernels, Next: Configuration of OpenBSD kernels, Prev: Configuration of Linux kernels 2.4.0 and higher, Up: Configuring the kernel
Configuration of FreeBSD kernels
--------------------------------
This section will contain information on how to configure your
FreeBSD kernel to support the universal tun/tap device. For 4.1 and
higher versions, this is included in the default kernel configuration,
for earlier systems (4.0 and earlier), you need to install the
universal tun/tap driver yourself.
Unfortunately somebody still has to write the text.

File: tinc.info, Node: Configuration of OpenBSD kernels, Next: Configuration of Solaris kernels, Prev: Configuration of FreeBSD kernels, Up: Configuring the kernel
Configuration of OpenBSD kernels
--------------------------------
This section will contain information on how to configure your
OpenBSD kernel to support the tun device. For 2.9 and 3.0 systems,
this is included in the default kernel configuration.
Unfortunately somebody still has to write the text.

File: tinc.info, Node: Configuration of Solaris kernels, Prev: Configuration of OpenBSD kernels, Up: Configuring the kernel
Configuration of Solaris kernels
--------------------------------
This section will contain information on how to configure your
Solaris kernel to support the universal tun/tap device. For Solaris 8
(SunOS 5.8), this is included in the default kernel configuration.
Unfortunately somebody still has to write the text.

File: tinc.info, Node: Libraries, Prev: Configuring the kernel, Up: Preparations
Libraries
=========
Before you can configure or build tinc, you need to have the OpenSSL
library installed on your system. If you try to configure tinc without
having installed it, configure will give you an error message, and stop.
* Menu:
* OpenSSL::
* zlib::

File: tinc.info, Node: OpenSSL, Next: zlib, Prev: Libraries, Up: Libraries
OpenSSL
-------
For all cryptography-related functions, tinc uses the functions
provided by the OpenSSL library.
If this library is not installed, you wil get an error when
configuring tinc for build. Support for running tinc without having
OpenSSL installed _may_ be added in the future.
You can use your operating system's package manager to install this
if available. Make sure you install the development AND runtime
versions of this package.
If you have to install OpenSSL manually, you can get the source code
from <http://www.openssl.org/>. Instructions on how to configure,
build and install this package are included within the package. Please
make sure you build development and runtime libraries (which is the
default).
If you installed the OpenSSL libraries from source, it may be
necessary to let configure know where they are, by passing configure
one of the -with-openssl-* parameters.
--with-openssl=DIR OpenSSL library and headers prefix
--with-openssl-include=DIR OpenSSL headers directory
(Default is OPENSSL_DIR/include)
--with-openssl-lib=DIR OpenSSL library directory
(Default is OPENSSL_DIR/lib)
License
.......
Since the license under which OpenSSL is distributed is not directly
compatible with the terms of the GNU GPL
`http://www.openssl.org/support/faq.html#LEGAL2', therefore we include
an addition to the GPL (see also the file COPYING.README):
This program is released under the GPL with the additional
exemption that compiling, linking, and/or using OpenSSL is
allowed. You may provide binary packages linked to the OpenSSL
libraries, provided that all other requirements of the GPL are met.

File: tinc.info, Node: zlib, Prev: OpenSSL, Up: Libraries
zlib
----
For the optional compression of UDP packets, tinc uses the functions
provided by the zlib library.
If this library is not installed, you wil get an error when
configuring tinc for build. Support for running tinc without having
zlib installed _may_ be added in the future.
You can use your operating system's package manager to install this
if available. Make sure you install the development AND runtime
versions of this package.
If you have to install zlib manually, you can get the source code
from <http://www.gzip.org/zlib/>. Instructions on how to configure,
build and install this package are included within the package. Please
make sure you build development and runtime libraries (which is the
default).

File: tinc.info, Node: Installation, Next: Configuration, Prev: Preparations, Up: Top
Installation
************
If you use Debian, you may want to install one of the precompiled
packages for your system. These packages are equipped with system
startup scripts and sample configurations.
If you cannot use one of the precompiled packages, or you want to
compile tinc for yourself, you can use the source. The source is
distributed under the GNU General Public License (GPL). Download the
source from the download page (http://tinc.nl.linux.org/download.html),
which has the checksums of these files listed; you may wish to check
these with md5sum before continuing.
tinc comes in a convenient autoconf/automake package, which you can
just treat the same as any other package. Which is just untar it, type
`configure' and then `make'. More detailed instructions are in the
file `INSTALL', which is included in the source distribution.
* Menu:
* Building and installing tinc::
* System files::

File: tinc.info, Node: Building and installing tinc, Next: System files, Prev: Installation, Up: Installation
Building and installing tinc
============================
Detailed instructions on configuring the source, building tinc and
installing tinc can be found in the file called `INSTALL'.
If you happen to have a binary package for tinc for your
distribution, you can use the package management tools of that
distribution to install tinc. The documentation that comes along with
your distribution will tell you how to do that.

File: tinc.info, Node: System files, Prev: Building and installing tinc, Up: Installation
System files
============
Before you can run tinc, you must make sure you have all the needed
files on your system.
* Menu:
* Device files::
* Other files::

File: tinc.info, Node: Device files, Next: Other files, Prev: System files, Up: System files
Device files
------------
First, you'll need the special device file(s) that form the interface
between the kernel and the daemon.
The permissions for these files have to be such that only the super
user may read/write to this file. You'd want this, because otherwise
eavesdropping would become a bit too easy. This does, however, imply
that you'd have to run tincd as root.
If you use Linux and have a kernel version prior to 2.4.0, you have
to make the ethertap devices:
mknod -m 600 /dev/tap0 c 36 16
chown 0.0 /dev/tap0
mknod -m 600 /dev/tap1 c 36 17
chown 0.0 /dev/tap0
...
mknod -m 600 /dev/tap_N_ c 36 _N+16_
chown 0.0 /dev/tap_N_
There is a maximum of 16 ethertap devices.
If you use the universal tun/tap driver, you have to create the
following device file (unless it already exist):
mknod -m 600 /dev/tun c 10 200
chown 0.0 /dev/tun
If you use Linux, and you run the new 2.4 kernel using the devfs
filesystem, then the tun/tap device will probably be automatically
generated as `/dev/misc/net/tun'.
Unlike the ethertap device, you do not need multiple device files if
you are planning to run multiple tinc daemons.

File: tinc.info, Node: Other files, Prev: Device files, Up: System files
Other files
-----------
`/etc/networks'
...............
You may add a line to `/etc/networks' so that your VPN will get a
symbolic name. For example:
myvpn 10.0.0.0
`/etc/services'
...............
You may add this line to `/etc/services'. The effect is that you
may supply a `tinc' as a valid port number to some programs. The
number 655 is registered with the IANA.
tinc 655/tcp TINC
tinc 655/udp TINC
# Ivo Timmermans <itimmermans@bigfoot.com>

File: tinc.info, Node: Configuration, Next: Running tinc, Prev: Installation, Up: Top
Configuration
*************
* Menu:
* Configuration introduction::
* Multiple networks::
* How connections work::
* Configuration files::
* Generating keypairs::
* Network interfaces::
* Example configuration::

File: tinc.info, Node: Configuration introduction, Next: Multiple networks, Prev: Configuration, Up: Configuration
Configuration introduction
==========================
Before actually starting to configure tinc and editing files, make
sure you have read this entire section so you know what to expect.
Then, make it clear to yourself how you want to organize your VPN: What
are the nodes (computers running tinc)? What IP addresses/subnets do
they have? What is the network mask of the entire VPN? Do you need
special firewall rules? Do you have to set up masquerading or
forwarding rules? These questions can only be answered by yourself,
you will not find the answers in this documentation. Make sure you
have an adequate understanding of networks in general. A good resource
on networking is the Linux Network Administrators Guide
(http://www.linuxdoc.org/LDP/nag2/).
If you have everything clearly pictured in your mind, proceed in the
following order: First, generate the configuration files (`tinc.conf',
your host configuration file, `tinc-up' and perhaps `tinc-down'). Then
generate the keypairs. Finally, distribute the host configuration
files. These steps are described in the subsections below.

File: tinc.info, Node: Multiple networks, Next: How connections work, Prev: Configuration introduction, Up: Configuration
Multiple networks
=================
In order to allow you to run more than one tinc daemon on one
computer, for instance if your computer is part of more than one VPN,
you can assign a "netname" to your VPN. It is not required if you only
run one tinc daemon, it doesn't even have to be the same on all the
sites of your VPN, but it is recommended that you choose one anyway.
We will asume you use a netname throughout this document. This
means that you call tincd with the -n argument, which will assign a
netname to this daemon.
The effect of this is that the daemon will set its configuration
"root" to /etc/tinc/netname/, where netname is your argument to the -n
option. You'll notice that it appears in syslog as "tinc.netname".
However, it is not strictly necessary that you call tinc with the -n
option. In this case, the network name would just be empty, and it will
be used as such. tinc now looks for files in /etc/tinc/, instead of
/etc/tinc/netname/; the configuration file should be
/etc/tinc/tinc.conf, and the host configuration files are now expected
to be in /etc/tinc/hosts/.
But it is highly recommended that you use this feature of tinc,
because it will be so much clearer whom your daemon talks to. Hence,
we will assume that you use it.

File: tinc.info, Node: How connections work, Next: Configuration files, Prev: Multiple networks, Up: Configuration
How connections work
====================
When tinc starts up, it parses the command-line options and then
reads in the configuration file. If it sees a `ConnectTo' value
pointing to another tinc daemon in the file, it will try to connect to
that other one. Whether this succeeds or not and whether `ConnectTo'
is specified or not, tinc will listen for incoming connection from
other deamons. If you did specify a `ConnectTo' value and the other
side is not responding, tinc will keep retrying. This means that once
started, tinc will stay running until you tell it to stop, and failures
to connect to other tinc daemons will not stop your tinc daemon for
trying again later. This means you don't have to intervene if there
are any network problems.
There is no real distinction between a server and a client in tinc.
If you wish, you can view a tinc daemon without a `ConnectTo' value as
a server, and one which does specify such a value as a client. It does
not matter if two tinc daemons have a `ConnectTo' value pointing to
eachother however.

File: tinc.info, Node: Configuration files, Next: Generating keypairs, Prev: How connections work, Up: Configuration
Configuration files
===================
The actual configuration of the daemon is done in the file
`/etc/tinc/netname/tinc.conf' and at least one other file in the
directory `/etc/tinc/netname/hosts/'.
These file consists of comments (lines started with a #) or
assignments in the form of
Variable = Value.
The variable names are case insensitive, and any spaces, tabs,
newlines and carriage returns are ignored. Note: it is not required
that you put in the `=' sign, but doing so improves readability. If
you leave it out, remember to replace it with at least one space
character.
In this section all valid variables are listed in alphabetical order.
The default value is given between parentheses, other comments are
between square brackets and required directives are given in *bold*.
* Menu:
* Main configuration variables::
* Host configuration variables::
* How to configure::

File: tinc.info, Node: Main configuration variables, Next: Host configuration variables, Prev: Configuration files, Up: Configuration files
Main configuration variables
----------------------------
AddressFamily = <ipv4|ipv6|any> (ipv4) [experimental]
This option affects the address family of listening and outgoing
sockets. If "any" is selected, then depending on the operating
system both IPv4 and IPv6 or just IPv6 listening sockets will be
created.
BindToInterface = <interface> [experimental]
If you have more than one network interface in your computer, tinc
will by default listen on all of them for incoming connections.
It is possible to bind tinc to a single interface like eth0 or
ppp0 with this variable.
This option may not work on all platforms.
*ConnectTo = <name>*
Specifies which host to connect to on startup. Multiple ConnectTo
variables may be specified, if connecting to the first one fails
then tinc will try the next one, and so on. It is possible to
specify hostnames for dynamic IP addresses (like those given on
dyndns.org), tinc will not cache the resolved IP address.
If you don't specify a host with ConnectTo, regardless of whether a
value for ConnectPort is given, tinc won't connect at all, and will
instead just listen for incoming connections.
*Device = <device>* (/dev/tap0 or /dev/misc/net/tun)
The virtual network device to use. Note that you can only use one
device per daemon. See also *Note Device files::.
Hostnames = <yes|no> (no)
This option selects whether IP addresses (both real and on the VPN)
should be resolved. Since DNS lookups are blocking, it might
affect tinc's efficiency, even stopping the daemon for a few
seconds everytime it does a lookup if your DNS server is not
responding.
This does not affect resolving hostnames to IP addresses from the
configuration file.
Interface = <interface>
Defines the name of the interface corresponding to the virtual
network device. Depending on the operating system and the type of
device this may or may not actually set the name. Currently this
option only affects the Linux tun/tap device.
Mode = <router|switch|hub> (router)
This option selects the way packets are routed to other daemons.
router
In this mode Subnet variables in the host configuration files
will be used to form a routing table. Only unicast packets
of routable protocols (IPv4 and IPv6) are supported in this
mode.
switch
In this mode the MAC addresses of the packets on the VPN will
be used to dynamically create a routing table just like an
Ethernet switch does. Unicast, multicast and broadcast
packets of every protocol that runs over Ethernet are
supported in this mode at the cost of frequent broadcast ARP
requests and routing table updates.
hub
This mode is almost the same as the switch mode, but instead
every packet will be broadcast to the other daemons while no
routing table is managed.
KeyExpire = <seconds> (3600)
This option controls the time the encryption keys used to encrypt
the data are valid. It is common practice to change keys at
regular intervals to make it even harder for crackers, even though
it is thought to be nearly impossible to crack a single key.
MACExpire = <seconds> (600)
This option controls the amount of time MAC addresses are kept
before they are removed. This only has effect when Mode is set to
"switch".
*Name = <name>*
This is a symbolic name for this connection. It can be anything
PingTimeout = <seconds> (60)
The number of seconds of inactivity that tinc will wait before
sending a probe to the other end. If that other end doesn't
answer within that same amount of seconds, the connection is
terminated, and the others will be notified of this.
PriorityInheritance = <yes|no> (no) [experimental]
When this option is enabled the value of the TOS field of tunneled
IPv4 packets will be inherited by the UDP packets that are sent
out.
PrivateKey = <key> [obsolete]
This is the RSA private key for tinc. However, for safety reasons
it is advised to store private keys of any kind in separate files.
This prevents accidental eavesdropping if you are editting the
configuration file.
*PrivateKeyFile = <path>* [recommended]
This is the full path name of the RSA private key file that was
generated by "tincd -generate-keys". It must be a full path, not a
relative directory.
Note that there must be exactly one of PrivateKey or PrivateKeyFile
specified in the configuration file.

File: tinc.info, Node: Host configuration variables, Next: How to configure, Prev: Main configuration variables, Up: Configuration files
Host configuration variables
----------------------------
*Address = <IP address|hostname>* [recommended]
This variable is only required if you want to connect to this
host. It must resolve to the external IP address where the host
can be reached, not the one that is internal to the VPN.
Cipher = <cipher> (blowfish)
The symmetric cipher algorithm used to encrypt UDP packets. Any
cipher supported by OpenSSL is recognized.
Compression = <level> (0)
This option sets the level of compression used for UDP packets.
Possible values are 0 (off), 1 (fast) and any integer up to 9
(best).
Digest = <digest> (sha1)
The digest algorithm used to authenticate UDP packets. Any digest
supported by OpenSSL is recognized. Furthermore, specifying
"none" will turn off packet authentication.
IndirectData = <yes|no> (no)
This option specifies whether other tinc daemons besides the one
you specified with ConnectTo can make a direct connection to you.
This is especially useful if you are behind a firewall and it is
impossible to make a connection from the outside to your tinc
daemon. Otherwise, it is best to leave this option out or set it
to no.
MACLength = <length> (4)
The length of the message authentication code used to authenticate
UDP packets. Can be anything from 0 up to the length of the
digest produced by the digest algorithm.
Port = <port> (655)
Connect to the upstream host (given with the ConnectTo directive)
on port port. port may be given in decimal (default), octal (when
preceded by a single zero) o hexadecimal (prefixed with 0x). port
is the port number for both the UDP and the TCP (meta) connections.
PublicKey = <key> [obsolete]
This is the RSA public key for this host.
PublicKeyFile = <path> [obsolete]
This is the full path name of the RSA public key file that was
generated by "tincd -generate-keys". It must be a full path, not
a relative directory.
From version 1.0pre4 on tinc will store the public key directly
into the host configuration file in PEM format, the above two
options then are not necessary. Either the PEM format is used, or
exactly *one of the above two options* must be specified in each
host configuration file, if you want to be able to establish a
connection with that host.
Subnet = <address[/prefixlength]>
The subnet which this tinc daemon will serve. tinc tries to look
up which other daemon it should send a packet to by searching the
appropiate subnet. If the packet matches a subnet, it will be
sent to the daemon who has this subnet in his host configuration
file. Multiple subnet lines can be specified for each daemon.
Subnets can either be single MAC, IPv4 or IPv6 addresses, in which
case a subnet consisting of only that single address is assumed,
or they can be a IPv4 or IPv6 network address with a prefixlength.
Shorthand notations are not supported. For example, IPv4 subnets
must be in a form like 192.168.1.0/24, where 192.168.1.0 is the
network address and 24 is the number of bits set in the netmask.
Note that subnets like 192.168.1.1/24 are invalid! Read a
networking HOWTO/FAQ/guide if you don't understand this. IPv6
subnets are notated like fec0:0:0:1:0:0:0:0/64. MAC addresses are
notated like 0:1a:2b:3c:4d:5e.
prefixlength is the number of bits set to 1 in the netmask part;
for example: netmask 255.255.255.0 would become /24, 255.255.252.0
becomes /22. This conforms to standard CIDR notation as described
in RFC1519 (ftp://ftp.isi.edu/in-notes/rfc1519.txt)
TCPonly = <yes|no> (no) [experimental]
If this variable is set to yes, then the packets are tunnelled
over a TCP connection instead of a UDP connection. This is
especially useful for those who want to run a tinc daemon from
behind a masquerading firewall, or if UDP packet routing is
disabled somehow. Setting this options also implicitly sets
IndirectData.

File: tinc.info, Node: How to configure, Prev: Host configuration variables, Up: Configuration files
How to configure
----------------
Step 1. Creating the main configuration file
.............................................
The main configuration file will be called
`/etc/tinc/netname/tinc.conf'. Adapt the following example to create a
basic configuration file:
Name = _yourname_
Device = _/dev/tap0_
PrivateKeyFile = /etc/tinc/_netname_/rsa_key.priv
Then, if you know to which other tinc daemon(s) yours is going to
connect, add `ConnectTo' values.
Step 2. Creating your host configuration file
..............................................
If you added a line containing `Name = yourname' in the main
configuarion file, you will need to create a host configuration file
`/etc/tinc/netname/hosts/yourname'. Adapt the following example to
create a host configuration file:
Address = _your.real.hostname.org_
Subnet = _192.168.1.0/24_
You can also use an IP address instead of a hostname. The `Subnet'
specifies the address range that is local for _your part of the VPN
only_. If you have multiple address ranges you can specify more than
one `Subnet'. You might also need to add a `Port' if you want your
tinc daemon to run on a different port number than the default (655).

File: tinc.info, Node: Generating keypairs, Next: Network interfaces, Prev: Configuration files, Up: Configuration
Generating keypairs
===================
Now that you have already created the main configuration file and
your host configuration file, you can easily create a public/private
keypair by entering the following command:
tincd -n _netname_ -K
tinc will generate a public and a private key and ask you where to
put them. Just press enter to accept the defaults.

File: tinc.info, Node: Network interfaces, Next: Example configuration, Prev: Generating keypairs, Up: Configuration
Network interfaces
==================
Before tinc can start transmitting data over the tunnel, it must set
up the virtual network interface.
First, decide which IP addresses you want to have associated with
these devices, and what network mask they must have.
tinc will open a virtual network device (`/dev/tun', `/dev/tap0' or
similar), which will also create a network interface called something
like `tun0', `tap0', or, if you are using the Linux tun/tap driver, the
network interface will by default have the same name as the netname.
You can configure the network interface by putting ordinary
ifconfig, route, and other commands to a script named
`/etc/tinc/netname/tinc-up'. When tinc starts, this script will be
executed. When tinc exits, it will execute the script named
`/etc/tinc/netname/tinc-down', but normally you don't need to create
that script.
An example `tinc-up' script:
#!/bin/sh
ifconfig $INTERFACE hw ether fe:fd:0:0:0:0
ifconfig $INTERFACE 192.168.1.1 netmask 255.255.0.0
ifconfig $INTERFACE -arp
The first line sets up the MAC address of the network interface.
Due to the nature of how Ethernet and tinc work, it has to be set to
fe:fd:0:0:0:0 for tinc to work in it's normal mode. If you configured
tinc to work in `switch' or `hub' mode, the hardware address should
instead be set to a unique address instead of fe:fd:0:0:0:0.
You can use the environment variable $INTERFACE to get the name of
the interface. However, this might not be reliable. If in doubt, use
the name of the interface explicitly.
The next line gives the interface an IP address and a netmask. The
kernel will also automatically add a route to this interface, so
normally you don't need to add route commands to the `tinc-up' script.
The kernel will also bring the interface up after this command. The
netmask is the mask of the _entire_ VPN network, not just your own
subnet.
The last line tells the kernel not to use ARP on that interface.
Again this has to do with how Ethernet and tinc work. Use this option
only if you are running tinc under Linux and are using tinc's normal
routing mode.

File: tinc.info, Node: Example configuration, Prev: Network interfaces, Up: Configuration
Example configuration
=====================
Imagine the following situation. Branch A of our example `company'
wants to connect three branch offices in B, C and D using the Internet.
All four offices have a 24/7 connection to the Internet.
A is going to serve as the center of the network. B and C will
connect to A, and D will connect to C. Each office will be assigned
their own IP network, 10.x.0.0.
A: net 10.1.0.0 mask 255.255.0.0 gateway 10.1.54.1 internet IP 1.2.3.4
B: net 10.2.0.0 mask 255.255.0.0 gateway 10.2.1.12 internet IP 2.3.4.5
C: net 10.3.0.0 mask 255.255.0.0 gateway 10.3.69.254 internet IP 3.4.5.6
D: net 10.4.0.0 mask 255.255.0.0 gateway 10.4.3.32 internet IP 4.5.6.7
"gateway" is the VPN IP address of the machine that is running the
tincd. "internet IP" is the IP address of the firewall, which does not
need to run tincd, but it must do a port forwarding of TCP&UDP on port
655 (unless otherwise configured).
In this example, it is assumed that eth0 is the interface that
points to the inner (physical) LAN of the office, although this could
also be the same as the interface that leads to the Internet. The
configuration of the real interface is also shown as a comment, to give
you an idea of how these example host is set up. All branches use the
netname `company' for this particular VPN.
For Branch A
............
_BranchA_ would be configured like this:
In `/etc/tinc/company/tinc-up':
# Real interface of internal network:
# ifconfig eth0 10.1.54.1 netmask 255.255.0.0 broadcast 10.1.255.255
ifconfig tap0 hw ether fe:fd:0:0:0:0
ifconfig tap0 10.1.54.1 netmask 255.0.0.0
ifconfig tap0 -arp
and in `/etc/tinc/company/tinc.conf':
Name = BranchA
PrivateKey = /etc/tinc/company/rsa_key.priv
Device = /dev/tap0
On all hosts, /etc/tinc/company/hosts/BranchA contains:
Subnet = 10.1.0.0/16
Address = 1.2.3.4
Note that the IP addresses of eth0 and tap0 are the same.
This is quite possible, if you make sure that the netmasks of the interfaces are different.
It is in fact recommended to give give both real internal network interfaces and tap interfaces the same IP address,
since that will make things a lot easier to remember and set up.
-----BEGIN RSA PUBLIC KEY-----
...
-----END RSA PUBLIC KEY-----
For Branch B
............
In `/etc/tinc/company/tinc-up':
# Real interface of internal network:
# ifconfig eth0 10.2.43.8 netmask 255.255.0.0 broadcast 10.2.255.255
ifconfig tap0 hw ether fe:fd:0:0:0:0
ifconfig tap0 10.2.1.12 netmask 255.0.0.0
ifconfig tap0 -arp
and in `/etc/tinc/company/tinc.conf':
Name = BranchB
ConnectTo = BranchA
PrivateKey = /etc/tinc/company/rsa_key.priv
Note here that the internal address (on eth0) doesn't have to be the
same as on the tap0 device. Also, ConnectTo is given so that no-one can
connect to this node.
On all hosts, in `/etc/tinc/company/hosts/BranchB':
Subnet = 10.2.0.0/16
Address = 2.3.4.5
-----BEGIN RSA PUBLIC KEY-----
...
-----END RSA PUBLIC KEY-----
For Branch C
............
In `/etc/tinc/company/tinc-up':
# Real interface of internal network:
# ifconfig eth0 10.3.69.254 netmask 255.255.0.0 broadcast 10.3.255.255
ifconfig tap1 hw ether fe:fd:0:0:0:0
ifconfig tap1 10.3.69.254 netmask 255.0.0.0
ifconfig tap1 -arp
and in `/etc/tinc/company/tinc.conf':
Name = BranchC
ConnectTo = BranchA
Device = /dev/tap1
C already has another daemon that runs on port 655, so they have to
reserve another port for tinc. It knows the portnumber it has to listen
on from it's own host configuration file.
On all hosts, in `/etc/tinc/company/hosts/BranchC':
Address = 3.4.5.6
Subnet = 10.3.0.0/16
Port = 2000
-----BEGIN RSA PUBLIC KEY-----
...
-----END RSA PUBLIC KEY-----
For Branch D
............
In `/etc/tinc/company/tinc-up':
# Real interface of internal network:
# ifconfig eth0 10.4.3.32 netmask 255.255.0.0 broadcast 10.4.255.255
ifconfig company hw ether fe:fd:0:0:0:0
ifconfig company 10.4.3.32 netmask 255.0.0.0
ifconfig company -arp
and in `/etc/tinc/company/tinc.conf':
Name = BranchD
ConnectTo = BranchC
Device = /dev/misc/net/tun
PrivateKeyFile = /etc/tinc/company/rsa_key.priv
D will be connecting to C, which has a tincd running for this
network on port 2000. It knows the port number from the host
configuration file. Also note that since D uses the tun/tap driver,
the network interface will not be called `tun' or `tap0' or something
like that, but will have the same name as netname.
On all hosts, in `/etc/tinc/company/hosts/BranchD':
Subnet = 10.4.0.0/16
Address = 4.5.6.7
-----BEGIN RSA PUBLIC KEY-----
...
-----END RSA PUBLIC KEY-----
Key files
.........
A, B, C and D all have generated a public/private keypair with the
following command:
tincd -n company -K
The private key is stored in `/etc/tinc/company/rsa_key.priv', the
public key is put into the host configuration file in the
`/etc/tinc/company/hosts/' directory. During key generation, tinc
automatically guesses the right filenames based on the -n option and
the Name directive in the `tinc.conf' file (if it is available).
Starting
........
After each branch has finished configuration and they have
distributed the host configuration files amongst them, they can start
their tinc daemons. They don't necessarily have to wait for the other
branches to have started their daemons, tinc will try connecting until
they are available.

File: tinc.info, Node: Running tinc, Next: Technical information, Prev: Configuration, Up: Top
Running tinc
************
If everything else is done, you can start tinc by typing the
following command:
tincd -n _netname_
tinc will detach from the terminal and continue to run in the
background like a good daemon. If there are any problems however you
can try to increase the debug level and look in the syslog to find out
what the problems are.
* Menu:
* Runtime options::
* Error messages::

File: tinc.info, Node: Runtime options, Next: Error messages, Up: Running tinc
Runtime options
===============
Besides the settings in the configuration file, tinc also accepts
some command line options.
This list is a longer version of that in the manpage. The latter is
generated automatically, so may be more up-to-date.
`--bypass-security'
Disables encryption and authentication. Only useful for debugging.
`-c, --config=PATH'
Read configuration options from the directory PATH. The default is
`/etc/tinc/netname/'.
`-d, --debug=LEVEL'
Set debug level to LEVEL. The higher the debug level, the more
gets logged. Everything goes via syslog.
`-K, --generate-keys[=BITS]'
Generate public/private keypair of BITS length. If BITS is not
specified, 1024 is the default. tinc will ask where you want to
store the files, but will default to the configuration directory
(you can use the -c or -n option in combination with -K). After
that, tinc will quit.
`--help'
Display a short reminder of these runtime options and terminate.
`-k, --kill[=SIGNAL]'
Attempt to kill a running tincd (optionally with the specified
SIGNAL instead of SIGTERM) and exit. Use it in conjunction with
the -n option to make sure you kill the right tinc daemon.
`-n, --net=NETNAME'
Connect to net NETNAME. *Note Multiple networks::.
`-D, --no-detach'
Don't fork and detach. This will also disable the automatic
restart mechanism for fatal errors.
`--version'
Output version information and exit.

File: tinc.info, Node: Error messages, Prev: Runtime options, Up: Running tinc
Error messages
==============
What follows is a list of the most common error messages you can see
when configuring tinc. Most of these messages are visible in the syslog
only, so keep an eye on it!
*Could not open /dev/tap0: No such device*
* You forgot to `modprobe netlink_dev' or `modprobe ethertap'.
* You forgot to compile `Netlink device emulation' in the
kernel.
*Can't write to /dev/misc/net/tun: No such device*
* You forgot to `modprobe tun'.
* You forgot to compile `Universal TUN/TAP driver' in the
kernel.
*Packet with destination 1.2.3.4 is looping back to us!*
* Something is not configured right. Packets are being sent out
to the virtual network device, but according to the Subnet
directives in your host configuration file, those packets
should go to your own host. Most common mistake is that you
have a Subnet line in your host configuration file with a
prefix length which is just as large as the prefix of the
virtual network interface. The latter should in almost all
cases be larger. Rethink your configuration. Note that you
will only see this message if you specified a debug level of
5 or higher!
* Chances are that a `Subnet = ...' line in the host
configuration file of this tinc daemon is wrong. Change it
to a subnet that is accepted locally by another interface, or
if that is not the case, try changing the prefix length into
/32.
*Network doesn't work, syslog shows only packets of length 46*
Jan 1 12:00:00 host tinc.net[1234]: Read packet of length 46 from tap device
Jan 1 12:00:00 host tinc.net[1234]: Trying to look up 0.0.192.168 in connection list failed!
* Add the `ifconfig $INTERFACE -arp' to tinc-up.
*Network address and prefix length do not match!*
* The Subnet field must contain a _network_ address.
* If you only want to use one IP address, set the netmask to
/32.
*This is a bug: net.c:253: 24: Some error*
* This is something that should not have happened. Please
report this, and tell us exactly what went wrong before you
got this message. In normal operation, these errors should
not occur.
*Error reading RSA key file `rsa_key.priv': No such file or directory*
* You must specify the complete pathname. Specifying a
relative path does not make sense here. tinc changes its
directory to / when starting (to avoid keeping a mount point
busy); and even if we built in a default directory to look
for these files, the key files are bound to be in a different
directory.

File: tinc.info, Node: Technical information, Next: About us, Prev: Running tinc, Up: Top
Technical information
*********************
* Menu:
* The connection::
* The meta-protocol::
* Security::

File: tinc.info, Node: The connection, Next: The meta-protocol, Prev: Technical information, Up: Technical information
The connection
==============
tinc is a daemon that takes VPN data and transmit that to another
host computer over the existing Internet infrastructure.
* Menu:
* The UDP tunnel::
* The meta-connection::
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