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This is tinc.info, produced by makeinfo version 4.11 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 version 1.0.9, a Virtual Private
Network daemon.
Copyright (C) 1998-2008 Ivo Timmermans, Guus Sliepen
<guus@tinc-vpn.org> and Wessel Dankers <wsl@tinc-vpn.org>.
$Id: tinc.texi 1597 2008-12-22 21:29:21Z guus $
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, Up: (dir)
Top
***
* Menu:
* Introduction::
* Preparations::
* Installation::
* Configuration::
* Running tinc::
* Technical information::
* Platform specific information::
* About us::
* Concept Index:: All used terms explained

File: tinc.info, Node: Introduction, Next: Preparations, Prev: Top, Up: Top
1 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:
* Virtual Private Networks::
* tinc:: About tinc
* Supported platforms::

File: tinc.info, Node: Virtual Private Networks, Next: tinc, Up: Introduction
1.1 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: Virtual Private Networks, Up: Introduction
1.2 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
1.3 Supported platforms
=======================
Tinc has been verified to work under Linux, FreeBSD, OpenBSD, NetBSD,
MacOS/X (Darwin), Solaris, and Windows (both natively and in a Cygwin
environment), 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://www.tinc-vpn.org/platforms'.

File: tinc.info, Node: Preparations, Next: Installation, Prev: Introduction, Up: Top
2 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, Up: Preparations
2.1 Configuring the kernel
==========================
* Menu:
* Configuration of Linux kernels::
* Configuration of FreeBSD kernels::
* Configuration of OpenBSD kernels::
* Configuration of NetBSD kernels::
* Configuration of Solaris kernels::
* Configuration of Darwin (MacOS/X) kernels::
* Configuration of Windows::

File: tinc.info, Node: Configuration of Linux kernels, Next: Configuration of FreeBSD kernels, Up: Configuring the kernel
2.1.1 Configuration of Linux kernels
------------------------------------
For tinc to work, you need a kernel that supports the Universal tun/tap
device. Most distributions come with kernels that already support this.
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 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, Up: Configuring the kernel
2.1.2 Configuration of FreeBSD kernels
--------------------------------------
For FreeBSD version 4.1 and higher, tun and tap drivers are included in
the default kernel configuration. Using tap devices is recommended.

File: tinc.info, Node: Configuration of OpenBSD kernels, Next: Configuration of NetBSD kernels, Prev: Configuration of FreeBSD kernels, Up: Configuring the kernel
2.1.3 Configuration of OpenBSD kernels
--------------------------------------
For OpenBSD version 2.9 and higher, the tun driver is included in the
default kernel configuration. There is also a kernel patch from
`http://diehard.n-r-g.com/stuff/openbsd/' which adds a tap device to
OpenBSD which should work with tinc, but with recent versions of
OpenBSD, a tun device can act as a tap device by setting the link0
option with ifconfig.

File: tinc.info, Node: Configuration of NetBSD kernels, Next: Configuration of Solaris kernels, Prev: Configuration of OpenBSD kernels, Up: Configuring the kernel
2.1.4 Configuration of NetBSD kernels
-------------------------------------
For NetBSD version 1.5.2 and higher, the tun driver is included in the
default kernel configuration.
Tunneling IPv6 may not work on NetBSD's tun device.

File: tinc.info, Node: Configuration of Solaris kernels, Next: Configuration of Darwin (MacOS/X) kernels, Prev: Configuration of NetBSD kernels, Up: Configuring the kernel
2.1.5 Configuration of Solaris kernels
--------------------------------------
For Solaris 8 (SunOS 5.8) and higher, the tun driver may or may not be
included in the default kernel configuration. If it isn't, the source
can be downloaded from `http://vtun.sourceforge.net/tun/'. For x86 and
sparc64 architectures, precompiled versions can be found at
`http://www.monkey.org/~dugsong/fragroute/'. If the `net/if_tun.h'
header file is missing, install it from the source package.

File: tinc.info, Node: Configuration of Darwin (MacOS/X) kernels, Next: Configuration of Windows, Prev: Configuration of Solaris kernels, Up: Configuring the kernel
2.1.6 Configuration of Darwin (MacOS/X) kernels
-----------------------------------------------
Tinc on Darwin relies on a tunnel driver for its data acquisition from
the kernel. Tinc supports either the driver from
`http://www-user.rhrk.uni-kl.de/~nissler/tuntap/', which supports both
tun and tap style devices, and also the driver from from
`http://chrisp.de/en/projects/tunnel.html'. The former driver is
recommended. The tunnel driver must be loaded before starting tinc
with the following command:
kmodload tunnel

File: tinc.info, Node: Configuration of Windows, Prev: Configuration of Darwin (MacOS/X) kernels, Up: Configuring the kernel
2.1.7 Configuration of Windows
------------------------------
You will need to install the latest TAP-Win32 driver from OpenVPN. You
can download it from `http://openvpn.sourceforge.net'. Using the
Network Connections control panel, configure the TAP-Win32 network
interface in the same way as you would do from the tinc-up script, as
explained in the rest of the documentation.

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

File: tinc.info, Node: OpenSSL, Next: zlib, Up: Libraries
2.2.1 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
.......
The complete source code of tinc is covered by the GNU GPL version 2.
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', we include an
exemption to the GPL (see also the file COPYING.README) to allow
everyone to create a statically or dynamically linked executable:
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.
Since the LZO library used by tinc is also covered by the GPL, we
also present the following exemption:
Hereby I grant a special exception to the tinc VPN project
(http://www.tinc-vpn.org/) to link the LZO library with the
OpenSSL library (http://www.openssl.org).
Markus F.X.J. Oberhumer

File: tinc.info, Node: zlib, Next: lzo, Prev: OpenSSL, Up: Libraries
2.2.2 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: lzo, Prev: zlib, Up: Libraries
2.2.3 lzo
---------
Another form of compression is offered using the lzo library.
If this library is not installed, you wil get an error when
configuring tinc for build. Support for running tinc without having lzo
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 lzo manually, you can get the source code
from `http://www.oberhumer.com/opensource/lzo/'. 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
3 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://www.tinc-vpn.org/download), 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, Up: Installation
3.1 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.
* Menu:
* Darwin (MacOS/X) build environment::
* Cygwin (Windows) build environment::
* MinGW (Windows) build environment::

File: tinc.info, Node: Darwin (MacOS/X) build environment, Next: Cygwin (Windows) build environment, Up: Building and installing tinc
3.1.1 Darwin (MacOS/X) build environment
----------------------------------------
In order to build tinc on Darwin, you need to install the MacOS/X
Developer Tools from
`http://developer.apple.com/tools/macosxtools.html' and a recent
version of Fink from `http://fink.sourceforge.net/'.
After installation use fink to download and install the following
packages: autoconf25, automake, dlcompat, m4, openssl, zlib and lzo.

File: tinc.info, Node: Cygwin (Windows) build environment, Next: MinGW (Windows) build environment, Prev: Darwin (MacOS/X) build environment, Up: Building and installing tinc
3.1.2 Cygwin (Windows) build environment
----------------------------------------
If Cygwin hasn't already been installed, install it directly from
`http://www.cygwin.com/'.
When tinc is compiled in a Cygwin environment, it can only be run in
this environment, but all programs, including those started outside the
Cygwin environment, will be able to use the VPN. It will also support
all features.

File: tinc.info, Node: MinGW (Windows) build environment, Prev: Cygwin (Windows) build environment, Up: Building and installing tinc
3.1.3 MinGW (Windows) build environment
---------------------------------------
You will need to install the MinGW environment from
`http://www.mingw.org'.
When tinc is compiled using MinGW it runs natively under Windows, it
is not necessary to keep MinGW installed.
When detaching, tinc will install itself as a service, which will be
restarted automatically after reboots.

File: tinc.info, Node: System files, Prev: Building and installing tinc, Up: Installation
3.2 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, Up: System files
3.2.1 Device files
------------------
Most operating systems nowadays come with the necessary device files by
default, or they have a mechanism to create them on demand.
If you use Linux and do not have udev installed, you may need to
create the following device file if it does not exist:
mknod -m 600 /dev/net/tun c 10 200

File: tinc.info, Node: Other files, Prev: Device files, Up: System files
3.2.2 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 <ivo@tinc-vpn.org>

File: tinc.info, Node: Configuration, Next: Running tinc, Prev: Installation, Up: Top
4 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, Up: Configuration
4.1 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?
Do you want to run tinc in router mode or switch mode? 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
4.2 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
4.3 How connections work
========================
When tinc starts up, it parses the command-line options and then reads
in the configuration file tinc.conf. If it sees one or more
`ConnectTo' values pointing to other tinc daemons in that file, it will
try to connect to those other daemons. 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 temporary 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
each other however.

File: tinc.info, Node: Configuration files, Next: Generating keypairs, Prev: How connections work, Up: Configuration
4.4 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.
* Menu:
* Main configuration variables::
* Host configuration variables::
* Scripts::
* How to configure::

File: tinc.info, Node: Main configuration variables, Next: Host configuration variables, Up: Configuration files
4.4.1 Main configuration variables
----------------------------------
AddressFamily = <ipv4|ipv6|any> (any)
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.
BindToAddress = <ADDRESS> [experimental]
If your computer has more than one IPv4 or IPv6 address, tinc will
by default listen on all of them for incoming connections. It is
possible to bind only to a single address with this variable.
This option may not work on all platforms.
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 other tinc daemon to connect to on startup.
Multiple ConnectTo variables may be specified, in which case
outgoing connections to each specified tinc daemon are made. The
names should be known to this tinc daemon (i.e., there should be a
host configuration file for the name on the ConnectTo line).
If you don't specify a host with ConnectTo, tinc won't try to
connect to other daemons at all, and will instead just listen for
incoming connections.
Device = <DEVICE> (`/dev/tap0', `/dev/net/tun' or other depending on platform)
The virtual network device to use. Tinc will automatically detect
what kind of device it is. Note that you can only use one device
per daemon. Under Windows, use INTERFACE instead of DEVICE. Note
that you can only use one device per daemon. See also *note
Device files::.
DeviceType = <tun|tunnohead|tunifhead|tap> (only supported on BSD platforms)
The type of the virtual network device. Tinc will normally
automatically select the right type, and this option should not be
used. However, in case tinc does not seem to correctly interpret
packets received from the virtual network device, using this
option might help.
tun
Set type to tun. Depending on the platform, this can either
be with or without an address family header (see below).
tunnohead
Set type to tun without an address family header. Tinc will
expect packets read from the virtual network device to start
with an IP header. On some platforms IPv6 packets cannot be
read from or written to the device in this mode.
tunifhead
Set type to tun with an address family header. Tinc will
expect packets read from the virtual network device to start
with a four byte header containing the address family,
followed by an IP header. This mode should support both IPv4
and IPv6 packets.
tap
Set type to tap. Tinc will expect packets read from the
virtual network device to start with an Ethernet header.
GraphDumpFile = <FILENAME> [experimental]
If this option is present, tinc will dump the current network
graph to the file FILENAME every minute, unless there were no
changes to the graph. The file is in a format that can be read by
graphviz tools. If FILENAME starts with a pipe symbol |, then the
rest of the filename is interpreted as a shell command that is
executed, the graph is then sent to stdin.
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 of the interface.
Under Windows, this variable is used to select which network
interface will be used. If you specified a Device, this variable
is almost always already correctly set.
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.
This is the default mode, and unless you really know you need
another mode, don't change it.
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.
This mode is primarily useful if you want to bridge Ethernet
segments.
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> [required]
This is a symbolic name for this connection. The name should
consist only of alfanumeric and underscore characters (a-z, A-Z,
0-9 and _).
PingInterval = <SECONDS> (60)
The number of seconds of inactivity that tinc will wait before
sending a probe to the other end.
PingTimeout = <SECONDS> (5)
The number of seconds to wait for a response to pings or to allow
meta connections to block. If the other end doesn't respond within
this time, 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> (`/etc/tinc/NETNAME/rsa_key.priv')
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.
TunnelServer = <yes|no> (no) [experimental]
When this option is enabled tinc will no longer forward
information between other tinc daemons, and will only allow nodes
and subnets on the VPN which are present in the
`/etc/tinc/NETNAME/hosts/' directory.

File: tinc.info, Node: Host configuration variables, Next: Scripts, Prev: Main configuration variables, Up: Configuration files
4.4.2 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. Furthermore,
specifying "none" will turn off packet encryption. It is best to
use only those ciphers which support CBC mode.
Compression = <LEVEL> (0)
This option sets the level of compression used for UDP packets.
Possible values are 0 (off), 1 (fast zlib) and any integer up to 9
(best zlib), 10 (fast lzo) and 11 (best lzo).
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 = <BYTES> (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.
PMTU = <MTU> (1514)
This option controls the initial path MTU to this node.
PMTUDiscovery = <yes|no> (yes)
When this option is enabled, tinc will try to discover the path
MTU to this node. After the path MTU has been discovered, it will
be enforced on the VPN.
Port = <PORT> (655)
This is the port this tinc daemon listens on. You can use decimal
portnumbers or symbolic names (as listed in `/etc/services').
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)
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: Scripts, Next: How to configure, Prev: Host configuration variables, Up: Configuration files
4.4.3 Scripts
-------------
Apart from reading the server and host configuration files, tinc can
also run scripts at certain moments. Under Windows (not Cygwin), the
scripts should have the extension .bat.
`/etc/tinc/NETNAME/tinc-up'
This is the most important script. If it is present it will be
executed right after the tinc daemon has been started and has
connected to the virtual network device. It should be used to set
up the corresponding network interface, but can also be used to
start other things. Under Windows you can use the Network
Connections control panel instead of creating this script.
`/etc/tinc/NETNAME/tinc-down'
This script is started right before the tinc daemon quits.
`/etc/tinc/NETNAME/hosts/HOST-up'
This script is started when the tinc daemon with name HOST becomes
reachable.
`/etc/tinc/NETNAME/hosts/HOST-down'
This script is started when the tinc daemon with name HOST becomes
unreachable.
`/etc/tinc/NETNAME/host-up'
This script is started when any host becomes reachable.
`/etc/tinc/NETNAME/host-down'
This script is started when any host becomes unreachable.
`/etc/tinc/NETNAME/subnet-up'
This script is started when a Subnet becomes reachable. The
Subnet and the node it belongs to are passed in environment
variables.
`/etc/tinc/NETNAME/subnet-down'
This script is started when a Subnet becomes unreachable.
The scripts are started without command line arguments, but can make
use of certain environment variables. Under UNIX like operating
systems the names of environment variables must be preceded by a $ in
scripts. Under Windows, in `.bat' files, they have to be put between %
signs.
`NETNAME'
If a netname was specified, this environment variable contains it.
`NAME'
Contains the name of this tinc daemon.
`DEVICE'
Contains the name of the virtual network device that tinc uses.
`INTERFACE'
Contains the name of the virtual network interface that tinc uses.
This should be used for commands like ifconfig.
`NODE'
When a host becomes (un)reachable, this is set to its name. If a
subnet becomes (un)reachable, this is set to the owner of that
subnet.
`REMOTEADDRESS'
When a host becomes (un)reachable, this is set to its real address.
`REMOTEPORT'
When a host becomes (un)reachable, this is set to the port number
it uses for communication with other tinc daemons.
`SUBNET'
When a subnet becomes (un)reachable, this is set to the subnet.

File: tinc.info, Node: How to configure, Prev: Scripts, Up: Configuration files
4.4.4 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'
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
4.5 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
4.6 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'. If you are using the Linux tun/tap driver, the
network interface will by default have the same name as the NETNAME.
Under Windows you can change the name of the network interface from the
Network Connections control panel.
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 192.168.1.1 netmask 255.255.0.0
This script 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 exact syntax of the ifconfig and route commands differs from
platform to platform. You can look up the commands for setting
addresses and adding routes in *note Platform specific information::,
but it is best to consult the manpages of those utilities on your
platform.

File: tinc.info, Node: Example configuration, Prev: Network interfaces, Up: Configuration
4.7 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
Here, "gateway" is the VPN IP address of the machine that is running
the tincd, and "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 and
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
ifconfig $INTERFACE 10.1.54.1 netmask 255.0.0.0
and in `/etc/tinc/company/tinc.conf':
Name = BranchA
Device = /dev/tap0
On all hosts, `/etc/tinc/company/hosts/BranchA' contains:
Subnet = 10.1.0.0/16
Address = 1.2.3.4
-----BEGIN RSA PUBLIC KEY-----
...
-----END RSA PUBLIC KEY-----
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.
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
ifconfig $INTERFACE 10.2.1.12 netmask 255.0.0.0
and in `/etc/tinc/company/tinc.conf':
Name = BranchB
ConnectTo = BranchA
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
ifconfig $INTERFACE 10.3.69.254 netmask 255.0.0.0
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
ifconfig $INTERFACE 10.4.3.32 netmask 255.0.0.0
and in `/etc/tinc/company/tinc.conf':
Name = BranchD
ConnectTo = BranchC
Device = /dev/net/tun
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
5 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::
* Signals::
* Debug levels::
* Solving problems::
* Error messages::
* Sending bug reports::

File: tinc.info, Node: Runtime options, Next: Signals, Up: Running tinc
5.1 Runtime options
===================
Besides the settings in the configuration file, tinc also accepts some
command line options.
`-c, --config=PATH'
Read configuration options from the directory PATH. The default is
`/etc/tinc/NETNAME/'.
`-D, --no-detach'
Don't fork and detach. This will also disable the automatic
restart mechanism for fatal errors.
`-d, --debug=LEVEL'
Set debug level to LEVEL. The higher the debug level, the more
gets logged. Everything goes via syslog.
`-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. Under
native Windows the optional argument is ignored, the service will
always be stopped and removed.
`-n, --net=NETNAME'
Use configuration for net NETNAME. *Note Multiple networks::.
`-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.
`-L, --mlock'
Lock tinc into main memory. This will prevent sensitive data like
shared private keys to be written to the system swap
files/partitions.
`--logfile[=FILE]'
Write log entries to a file instead of to the system logging
facility. If FILE is omitted, the default is
`/var/log/tinc.NETNAME.log'.
`--pidfile=FILE'
Write PID to FILE instead of `/var/run/tinc.NETNAME.pid'.
`--bypass-security'
Disables encryption and authentication. Only useful for debugging.
`--help'
Display a short reminder of these runtime options and terminate.
`--version'
Output version information and exit.

File: tinc.info, Node: Signals, Next: Debug levels, Prev: Runtime options, Up: Running tinc
5.2 Signals
===========
You can also send the following signals to a running tincd process:
`ALRM'
Forces tinc to try to connect to all uplinks immediately. Usually
tinc attempts to do this itself, but increases the time it waits
between the attempts each time it failed, and if tinc didn't
succeed to connect to an uplink the first time after it started,
it defaults to the maximum time of 15 minutes.
`HUP'
Partially rereads configuration files. Connections to hosts whose
host config file are removed are closed. New outgoing connections
specified in `tinc.conf' will be made.
`INT'
Temporarily increases debug level to 5. Send this signal again to
revert to the original level.
`USR1'
Dumps the connection list to syslog.
`USR2'
Dumps virtual network device statistics, all known nodes, edges
and subnets to syslog.
`WINCH'
Purges all information remembered about unreachable nodes.

File: tinc.info, Node: Debug levels, Next: Solving problems, Prev: Signals, Up: Running tinc
5.3 Debug levels
================
The tinc daemon can send a lot of messages to the syslog. The higher
the debug level, the more messages it will log. Each level inherits
all messages of the previous level:
`0'
This will log a message indicating tinc has started along with a
version number. It will also log any serious error.
`1'
This will log all connections that are made with other tinc
daemons.
`2'
This will log status and error messages from scripts and other
tinc daemons.
`3'
This will log all requests that are exchanged with other tinc
daemons. These include authentication, key exchange and connection
list updates.
`4'
This will log a copy of everything received on the meta socket.
`5'
This will log all network traffic over the virtual private network.

File: tinc.info, Node: Solving problems, Next: Error messages, Prev: Debug levels, Up: Running tinc
5.4 Solving problems
====================
If tinc starts without problems, but if the VPN doesn't work, you will
have to find the cause of the problem. The first thing to do is to
start tinc with a high debug level in the foreground, so you can
directly see everything tinc logs:
tincd -n NETNAME -d5 -D
If tinc does not log any error messages, then you might want to
check the following things:
* `tinc-up' script Does this script contain the right commands?
Normally you must give the interface the address of this host on
the VPN, and the netmask must be big enough so that the entire VPN
is covered.
* Subnet Does the Subnet (or Subnets) in the host configuration file
of this host match the portion of the VPN that belongs to this
host?
* Firewalls and NATs Do you have a firewall or a NAT device (a
masquerading firewall or perhaps an ADSL router that performs
masquerading)? If so, check that it allows TCP and UDP traffic on
port 655. If it masquerades and the host running tinc is behind
it, make sure that it forwards TCP and UDP traffic to port 655 to
the host running tinc. You can add `TCPOnly = yes' to your host
config file to force tinc to only use a single TCP connection,
this works through most firewalls and NATs.

File: tinc.info, Node: Error messages, Next: Sending bug reports, Prev: Solving problems, Up: Running tinc
5.5 Error messages
==================
What follows is a list of the most common error messages you might find
in the logs. Some of them will only be visible if the debug level is
high enough.
`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/net/tun: No such device'
* You forgot to `modprobe tun'.
* You forgot to compile `Universal TUN/TAP driver' in the
kernel.
* The tun device is located somewhere else in `/dev/'.
`Network address and prefix length do not match!'
* The Subnet field must contain a _network_ address, trailing
bits should be 0.
* If you only want to use one IP address, set the netmask to
/32.
`Error reading RSA key file `rsa_key.priv': No such file or directory'
* You forgot to create a public/private keypair.
* Specify the complete pathname to the private key file with
the `PrivateKeyFile' option.
`Warning: insecure file permissions for RSA private key file `rsa_key.priv'!'
* The private key file is readable by users other than root.
Use chmod to correct the file permissions.
`Creating metasocket failed: Address family not supported'
* By default tinc tries to create both IPv4 and IPv6 sockets.
On some platforms this might not be implemented. If the logs
show `Ready' later on, then at least one metasocket was
created, and you can ignore this message. You can add
`AddressFamily = ipv4' to `tinc.conf' to prevent this from
happening.
`Cannot route packet: unknown IPv4 destination 1.2.3.4'
* You try to send traffic to a host on the VPN for which no
Subnet is known.
* If it is a broadcast address (ending in .255), it probably is
a samba server or a Windows host sending broadcast packets.
You can ignore it.
`Cannot route packet: ARP request for unknown address 1.2.3.4'
* You try to send traffic to a host on the VPN for which no
Subnet is known.
`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.
`Node foo (1.2.3.4) is not reachable'
* Node foo does not have a connection anymore, its tinc daemon
is not running or its connection to the Internet is broken.
`Received UDP packet from unknown source 1.2.3.4 (port 12345)'
* If you see this only sporadically, it is harmless and caused
by a node sending packets using an old key.
* If you see this often and another node is not reachable
anymore, then a NAT (masquerading firewall) is changing the
source address of UDP packets. You can add `TCPOnly = yes'
to host configuration files to force all VPN traffic to go
over a TCP connection.
`Got bad/bogus/unauthorized REQUEST from foo (1.2.3.4 port 12345)'
* Node foo does not have the right public/private keypair.
Generate new keypairs and distribute them again.
* An attacker tries to gain access to your VPN.
* A network error caused corruption of metadata sent from foo.

File: tinc.info, Node: Sending bug reports, Prev: Error messages, Up: Running tinc
5.6 Sending bug reports
=======================
If you really can't find the cause of a problem, or if you suspect tinc
is not working right, you can send us a bugreport, see *note Contact
information::. Be sure to include the following information in your
bugreport:
* A clear description of what you are trying to achieve and what the
problem is.
* What platform (operating system, version, hardware architecture)
and which version of tinc you use.
* If compiling tinc fails, a copy of `config.log' and the error
messages you get.
* Otherwise, a copy of `tinc.conf', `tinc-up' and all files in the
`hosts/' directory.
* The output of the commands `ifconfig -a' and `route -n' (or
`netstat -rn' if that doesn't work).
* The output of any command that fails to work as it should (like
ping or traceroute).

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

File: tinc.info, Node: The connection, Next: The meta-protocol, Up: Technical information
6.1 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::

File: tinc.info, Node: The UDP tunnel, Next: The meta-connection, Up: The connection
6.1.1 The UDP tunnel
--------------------
The data itself is read from a character device file, the so-called
_virtual network device_. This device is associated with a network
interface. Any data sent to this interface can be read from the device,
and any data written to the device gets sent from the interface. There
are two possible types of virtual network devices: `tun' style, which
are point-to-point devices which can only handle IPv4 and/or IPv6
packets, and `tap' style, which are Ethernet devices and handle
complete Ethernet frames.
So when tinc reads an Ethernet frame from the device, it determines
its type. When tinc is in it's default routing mode, it can handle IPv4
and IPv6 packets. Depending on the Subnet lines, it will send the
packets off to their destination IP address. In the `switch' and `hub'
mode, tinc will use broadcasts and MAC address discovery to deduce the
destination of the packets. Since the latter modes only depend on the
link layer information, any protocol that runs over Ethernet is
supported (for instance IPX and Appletalk). However, only `tap' style
devices provide this information.
After the destination has been determined, the packet will be
compressed (optionally), a sequence number will be added to the packet,
the packet will then be encrypted and a message authentication code
will be appended.
When that is done, time has come to actually transport the packet to
the destination computer. We do this by sending the packet over an UDP
connection to the destination host. This is called _encapsulating_,
the VPN packet (though now encrypted) is encapsulated in another IP
datagram.
When the destination receives this packet, the same thing happens,
only in reverse. So it checks the message authentication code,
decrypts the contents of the UDP datagram, checks the sequence number
and writes the decrypted information to its own virtual network device.
If the virtual network device is a `tun' device (a point-to-point
tunnel), there is no problem for the kernel to accept a packet.
However, if it is a `tap' device (this is the only available type on
FreeBSD), the destination MAC address must match that of the virtual
network interface. If tinc is in it's default routing mode, ARP does
not work, so the correct destination MAC can not be known by the
sending host. Tinc solves this by letting the receiving end detect the
MAC address of its own virtual network interface and overwriting the
destination MAC address of the received packet.
In switch or hub modes ARP does work so the sender already knows the
correct destination MAC address. In those modes every interface should
have a unique MAC address, so make sure they are not the same. Because
switch and hub modes rely on MAC addresses to function correctly, these
modes cannot be used on the following operating systems which don't
have a `tap' style virtual network device: OpenBSD, NetBSD, Darwin and
Solaris.

File: tinc.info, Node: The meta-connection, Prev: The UDP tunnel, Up: The connection
6.1.2 The meta-connection
-------------------------
Having only a UDP connection available is not enough. Though suitable
for transmitting data, we want to be able to reliably send other
information, such as routing and session key information to somebody.
TCP is a better alternative, because it already contains protection
against information being lost, unlike UDP.
So we establish two connections. One for the encrypted VPN data,
and one for other information, the meta-data. Hence, we call the second
connection the meta-connection. We can now be sure that the
meta-information doesn't get lost on the way to another computer.
Like with any communication, we must have a protocol, so that
everybody knows what everything stands for, and how she should react.
Because we have two connections, we also have two protocols. The
protocol used for the UDP data is the "data-protocol," the other one is
the "meta-protocol."
The reason we don't use TCP for both protocols is that UDP is much
better for encapsulation, even while it is less reliable. The real
problem is that when TCP would be used to encapsulate a TCP stream
that's on the private network, for every packet sent there would be
three ACKs sent instead of just one. Furthermore, if there would be a
timeout, both TCP streams would sense the timeout, and both would start
re-sending packets.

File: tinc.info, Node: The meta-protocol, Next: Security, Prev: The connection, Up: Technical information
6.2 The meta-protocol
=====================
The meta protocol is used to tie all tinc daemons together, and
exchange information about which tinc daemon serves which virtual
subnet.
The meta protocol consists of requests that can be sent to the other
side. Each request has a unique number and several parameters. All
requests are represented in the standard ASCII character set. It is
possible to use tools such as telnet or netcat to connect to a tinc
daemon started with the -bypass-security option and to read and write
requests by hand, provided that one understands the numeric codes sent.
The authentication scheme is described in *note Authentication
protocol::. After a successful authentication, the server and the
client will exchange all the information about other tinc daemons and
subnets they know of, so that both sides (and all the other tinc
daemons behind them) have their information synchronised.
message
------------------------------------------------------------------
ADD_EDGE node1 node2 21.32.43.54 655 222 0
| | | | | +-> options
| | | | +----> weight
| | | +--------> UDP port of node2
| | +----------------> real address of node2
| +-------------------------> name of destination node
+-------------------------------> name of source node
ADD_SUBNET node 192.168.1.0/24
| | +--> prefixlength
| +--------> network address
+------------------> owner of this subnet
------------------------------------------------------------------
The ADD_EDGE messages are to inform other tinc daemons that a
connection between two nodes exist. The address of the destination node
is available so that VPN packets can be sent directly to that node.
The ADD_SUBNET messages inform other tinc daemons that certain
subnets belong to certain nodes. tinc will use it to determine to which
node a VPN packet has to be sent.
message
------------------------------------------------------------------
DEL_EDGE node1 node2
| +----> name of destination node
+----------> name of source node
DEL_SUBNET node 192.168.1.0/24
| | +--> prefixlength
| +--------> network address
+------------------> owner of this subnet
------------------------------------------------------------------
In case a connection between two daemons is closed or broken,
DEL_EDGE messages are sent to inform the other daemons of that fact.
Each daemon will calculate a new route to the the daemons, or mark them
unreachable if there isn't any.
message
------------------------------------------------------------------
REQ_KEY origin destination
| +--> name of the tinc daemon it wants the key from
+----------> name of the daemon that wants the key
ANS_KEY origin destination 4ae0b0a82d6e0078 91 64 4
| | \______________/ | | +--> MAC length
| | | | +-----> digest algorithm
| | | +--------> cipher algorithm
| | +--> 128 bits key
| +--> name of the daemon that wants the key
+----------> name of the daemon that uses this key
KEY_CHANGED origin
+--> daemon that has changed it's packet key
------------------------------------------------------------------
The keys used to encrypt VPN packets are not sent out directly. This
is because it would generate a lot of traffic on VPNs with many
daemons, and chances are that not every tinc daemon will ever send a
packet to every other daemon. Instead, if a daemon needs a key it sends
a request for it via the meta connection of the nearest hop in the
direction of the destination.
daemon message
------------------------------------------------------------------
origin PING
dest. PONG
------------------------------------------------------------------
There is also a mechanism to check if hosts are still alive. Since
network failures or a crash can cause a daemon to be killed without
properly shutting down the TCP connection, this is necessary to keep an
up to date connection list. PINGs are sent at regular intervals, except
when there is also some other traffic. A little bit of salt (random
data) is added with each PING and PONG message, to make sure that long
sequences of PING/PONG messages without any other traffic won't result
in known plaintext.
This basically covers what is sent over the meta connection by tinc.

File: tinc.info, Node: Security, Prev: The meta-protocol, Up: Technical information
6.3 Security
============
Tinc got its name from "TINC," short for _There Is No Cabal_; the
alleged Cabal was/is an organisation that was said to keep an eye on the
entire Internet. As this is exactly what you _don't_ want, we named
the tinc project after TINC.
But in order to be "immune" to eavesdropping, you'll have to encrypt
your data. Because tinc is a _Secure_ VPN (SVPN) daemon, it does
exactly that: encrypt. Tinc by default uses blowfish encryption with
128 bit keys in CBC mode, 32 bit sequence numbers and 4 byte long
message authentication codes to make sure eavesdroppers cannot get and
cannot change any information at all from the packets they can
intercept. The encryption algorithm and message authentication
algorithm can be changed in the configuration. The length of the message
authentication codes is also adjustable. The length of the key for the
encryption algorithm is always the default length used by OpenSSL.
* Menu:
* Authentication protocol::
* Encryption of network packets::
* Security issues::

File: tinc.info, Node: Authentication protocol, Next: Encryption of network packets, Up: Security
6.3.1 Authentication protocol
-----------------------------
A new scheme for authentication in tinc has been devised, which offers
some improvements over the protocol used in 1.0pre2 and 1.0pre3.
Explanation is below.
daemon message
--------------------------------------------------------------------------
client <attempts connection>
server <accepts connection>
client ID client 12
| +---> version
+-------> name of tinc daemon
server ID server 12
| +---> version
+-------> name of tinc daemon
client META_KEY 5f0823a93e35b69e...7086ec7866ce582b
\_________________________________/
+-> RSAKEYLEN bits totally random string S1,
encrypted with server's public RSA key
server META_KEY 6ab9c1640388f8f0...45d1a07f8a672630
\_________________________________/
+-> RSAKEYLEN bits totally random string S2,
encrypted with client's public RSA key
From now on:
- the client will symmetrically encrypt outgoing traffic using S1
- the server will symmetrically encrypt outgoing traffic using S2
client CHALLENGE da02add1817c1920989ba6ae2a49cecbda0
\_________________________________/
+-> CHALLEN bits totally random string H1
server CHALLENGE 57fb4b2ccd70d6bb35a64c142f47e61d57f
\_________________________________/
+-> CHALLEN bits totally random string H2
client CHAL_REPLY 816a86
+-> 160 bits SHA1 of H2
server CHAL_REPLY 928ffe
+-> 160 bits SHA1 of H1
After the correct challenge replies are received, both ends have proved
their identity. Further information is exchanged.
client ACK 655 123 0
| | +-> options
| +----> estimated weight
+--------> listening port of client
server ACK 655 321 0
| | +-> options
| +----> estimated weight
+--------> listening port of server
--------------------------------------------------------------------------
This new scheme has several improvements, both in efficiency and
security.
First of all, the server sends exactly the same kind of messages
over the wire as the client. The previous versions of tinc first
authenticated the client, and then the server. This scheme even allows
both sides to send their messages simultaneously, there is no need to
wait for the other to send something first. This means that any
calculations that need to be done upon sending or receiving a message
can also be done in parallel. This is especially important when doing
RSA encryption/decryption. Given that these calculations are the main
part of the CPU time spent for the authentication, speed is improved by
a factor 2.
Second, only one RSA encrypted message is sent instead of two. This
reduces the amount of information attackers can see (and thus use for a
cryptographic attack). It also improves speed by a factor two, making
the total speedup a factor 4.
Third, and most important: The symmetric cipher keys are exchanged
first, the challenge is done afterwards. In the previous authentication
scheme, because a man-in-the-middle could pass the challenge/chal_reply
phase (by just copying the messages between the two real tinc daemons),
but no information was exchanged that was really needed to read the
rest of the messages, the challenge/chal_reply phase was of no real
use. The man-in-the-middle was only stopped by the fact that only after
the ACK messages were encrypted with the symmetric cipher. Potentially,
it could even send it's own symmetric key to the server (if it knew the
server's public key) and read some of the metadata the server would
send it (it was impossible for the mitm to read actual network packets
though). The new scheme however prevents this.
This new scheme makes sure that first of all, symmetric keys are
exchanged. The rest of the messages are then encrypted with the
symmetric cipher. Then, each side can only read received messages if
they have their private key. The challenge is there to let the other
side know that the private key is really known, because a challenge
reply can only be sent back if the challenge is decrypted correctly,
and that can only be done with knowledge of the private key.
Fourth: the first thing that is sent via the symmetric cipher
encrypted connection is a totally random string, so that there is no
known plaintext (for an attacker) in the beginning of the encrypted
stream.

File: tinc.info, Node: Encryption of network packets, Next: Security issues, Prev: Authentication protocol, Up: Security
6.3.2 Encryption of network packets
-----------------------------------
A data packet can only be sent if the encryption key is known to both
parties, and the connection is activated. If the encryption key is not
known, a request is sent to the destination using the meta connection
to retrieve it. The packet is stored in a queue while waiting for the
key to arrive.
The UDP packet containing the network packet from the VPN has the
following layout:
... | IP header | UDP header | seqno | VPN packet | MAC | UDP trailer
\___________________/\_____/
| |
V +---> digest algorithm
Encrypted with symmetric cipher
So, the entire VPN packet is encrypted using a symmetric cipher,
including a 32 bits sequence number that is added in front of the
actual VPN packet, to act as a unique IV for each packet and to prevent
replay attacks. A message authentication code is added to the UDP
packet to prevent alteration of packets. By default the first 4 bytes
of the digest are used for this, but this can be changed using the
MACLength configuration variable.

File: tinc.info, Node: Security issues, Prev: Encryption of network packets, Up: Security
6.3.3 Security issues
---------------------
In August 2000, we discovered the existence of a security hole in all
versions of tinc up to and including 1.0pre2. This had to do with the
way we exchanged keys. Since then, we have been working on a new
authentication scheme to make tinc as secure as possible. The current
version uses the OpenSSL library and uses strong authentication with
RSA keys.
On the 29th of December 2001, Jerome Etienne posted a security
analysis of tinc 1.0pre4. Due to a lack of sequence numbers and a
message authentication code for each packet, an attacker could possibly
disrupt certain network services or launch a denial of service attack
by replaying intercepted packets. The current version adds sequence
numbers and message authentication codes to prevent such attacks.
On the 15th of September 2003, Peter Gutmann posted a security
analysis of tinc 1.0.1. He argues that the 32 bit sequence number used
by tinc is not a good IV, that tinc's default length of 4 bytes for the
MAC is too short, and he doesn't like tinc's use of RSA during
authentication. We do not know of a security hole in this version of
tinc, but tinc's security is not as strong as TLS or IPsec. We will
address these issues in tinc 2.0.
Cryptography is a hard thing to get right. We cannot make any
guarantees. Time, review and feedback are the only things that can
prove the security of any cryptographic product. If you wish to review
tinc or give us feedback, you are stronly encouraged to do so.

File: tinc.info, Node: Platform specific information, Next: About us, Prev: Technical information, Up: Top
7 Platform specific information
*******************************
* Menu:
* Interface configuration::
* Routes::

File: tinc.info, Node: Interface configuration, Next: Routes, Up: Platform specific information
7.1 Interface configuration
===========================
When configuring an interface, one normally assigns it an address and a
netmask. The address uniquely identifies the host on the network
attached to the interface. The netmask, combined with the address,
forms a subnet. It is used to add a route to the routing table
instructing the kernel to send all packets which fall into that subnet
to that interface. Because all packets for the entire VPN should go to
the virtual network interface used by tinc, the netmask should be such
that it encompasses the entire VPN.
For IPv4 addresses:
Linux `ifconfig' INTERFACE ADDRESS `netmask' NETMASK
Linux iproute2 `ip addr add' ADDRESS`/'PREFIXLENGTH `dev' INTERFACE
FreeBSD `ifconfig' INTERFACE ADDRESS `netmask' NETMASK
OpenBSD `ifconfig' INTERFACE ADDRESS `netmask' NETMASK
NetBSD `ifconfig' INTERFACE ADDRESS `netmask' NETMASK
Solaris `ifconfig' INTERFACE ADDRESS `netmask' NETMASK
Darwin (MacOS/X) `ifconfig' INTERFACE ADDRESS `netmask' NETMASK
Windows `netsh interface ip set address' INTERFACE `static' ADDRESS NETMASK
For IPv6 addresses:
Linux `ifconfig' INTERFACE `add' ADDRESS`/'PREFIXLENGTH
FreeBSD `ifconfig' INTERFACE `inet6' ADDRESS `prefixlen' PREFIXLENGTH
OpenBSD `ifconfig' INTERFACE `inet6' ADDRESS `prefixlen' PREFIXLENGTH
NetBSD `ifconfig' INTERFACE `inet6' ADDRESS `prefixlen' PREFIXLENGTH
Solaris `ifconfig' INTERFACE `inet6 plumb up'
`ifconfig' INTERFACE `inet6 addif' ADDRESS ADDRESS
Darwin (MacOS/X) `ifconfig' INTERFACE `inet6' ADDRESS `prefixlen' PREFIXLENGTH
Windows `netsh interface ipv6 add address' INTERFACE `static' ADDRESS/PREFIXLENGTH

File: tinc.info, Node: Routes, Prev: Interface configuration, Up: Platform specific information
7.2 Routes
==========
In some cases it might be necessary to add more routes to the virtual
network interface. There are two ways to indicate which interface a
packet should go to, one is to use the name of the interface itself,
another way is to specify the (local) address that is assigned to that
interface (LOCAL_ADDRESS). The former way is unambiguous and therefore
preferable, but not all platforms support this.
Adding routes to IPv4 subnets:
Linux `route add -net' NETWORK_ADDRESS `netmask' NETMASK INTERFACE
Linux iproute2 `ip route add' NETWORK_ADDRESS`/'PREFIXLENGTH `dev' INTERFACE
FreeBSD `route add' NETWORK_ADDRESS`/'PREFIXLENGTH LOCAL_ADDRESS
OpenBSD `route add' NETWORK_ADDRESS`/'PREFIXLENGTH LOCAL_ADDRESS
NetBSD `route add' NETWORK_ADDRESS`/'PREFIXLENGTH LOCAL_ADDRESS
Solaris `route add' NETWORK_ADDRESS`/'PREFIXLENGTH LOCAL_ADDRESS `-interface'
Darwin (MacOS/X) `route add' NETWORK_ADDRESS`/'PREFIXLENGTH LOCAL_ADDRESS
Windows `netsh routing ip add persistentroute' NETWORK_ADDRESS NETMASK INTERFACE
LOCAL_ADDRESS
Adding routes to IPv6 subnets:
Linux `route add -A inet6' NETWORK_ADDRESS`/'PREFIXLENGTH INTERFACE
Linux iproute2 `ip route add' NETWORK_ADDRESS`/'PREFIXLENGTH `dev' INTERFACE
FreeBSD `route add -inet6' NETWORK_ADDRESS`/'PREFIXLENGTH LOCAL_ADDRESS
OpenBSD `route add -inet6' NETWORK_ADDRESS LOCAL_ADDRESS `-prefixlen' PREFIXLENGTH
NetBSD `route add -inet6' NETWORK_ADDRESS LOCAL_ADDRESS `-prefixlen' PREFIXLENGTH
Solaris `route add -inet6' NETWORK_ADDRESS`/'PREFIXLENGTH LOCAL_ADDRESS `-interface'
Darwin (MacOS/X) ?
Windows `netsh interface ipv6 add route' NETWORK ADDRESS/PREFIXLENGTH INTERFACE

File: tinc.info, Node: About us, Next: Concept Index, Prev: Platform specific information, Up: Top
8 About us
**********
* Menu:
* Contact information::
* Authors::

File: tinc.info, Node: Contact information, Next: Authors, Up: About us
8.1 Contact information
=======================
Tinc's website is at `http://www.tinc-vpn.org/', this server is located
in the Netherlands.
We have an IRC channel on the FreeNode and OFTC IRC networks.
Connect to irc.freenode.net (http://www.freenode.net/) or irc.oftc.net
(http://www.oftc.net/) and join channel #tinc.

File: tinc.info, Node: Authors, Prev: Contact information, Up: About us
8.2 Authors
===========
Ivo Timmermans (zarq) (<ivo@tinc-vpn.org>)
Guus Sliepen (guus) (<guus@tinc-vpn.org>)
We have received a lot of valuable input from users. With their
help, tinc has become the flexible and robust tool that it is today.
We have composed a list of contributions, in the file called `THANKS' in
the source distribution.

File: tinc.info, Node: Concept Index, Prev: About us, Up: Top
Concept Index
*************
[index]
* Menu:
* ACK: Authentication protocol.
(line 10)
* ADD_EDGE: The meta-protocol. (line 23)
* ADD_SUBNET: The meta-protocol. (line 23)
* Address: Host configuration variables.
(line 6)
* AddressFamily: Main configuration variables.
(line 6)
* ANS_KEY: The meta-protocol. (line 64)
* authentication: Authentication protocol.
(line 6)
* binary package: Building and installing tinc.
(line 9)
* BindToAddress: Main configuration variables.
(line 12)
* BindToInterface: Main configuration variables.
(line 19)
* Cabal: Security. (line 6)
* CHAL_REPLY: Authentication protocol.
(line 10)
* CHALLENGE: Authentication protocol.
(line 10)
* CIDR notation: Host configuration variables.
(line 85)
* Cipher: Host configuration variables.
(line 11)
* client: How connections work.
(line 18)
* command line: Runtime options. (line 9)
* Compression: Host configuration variables.
(line 17)
* connection: The connection. (line 6)
* ConnectTo: Main configuration variables.
(line 27)
* daemon: Running tinc. (line 11)
* data-protocol: The meta-connection. (line 18)
* debug level: Runtime options. (line 17)
* debug levels: Debug levels. (line 6)
* DEL_EDGE: The meta-protocol. (line 47)
* DEL_SUBNET: The meta-protocol. (line 47)
* DEVICE: Scripts. (line 55)
* Device: Main configuration variables.
(line 38)
* device files: Device files. (line 6)
* DeviceType: Main configuration variables.
(line 45)
* Digest: Host configuration variables.
(line 22)
* encapsulating: The UDP tunnel. (line 30)
* encryption: Encryption of network packets.
(line 6)
* environment variables: Scripts. (line 43)
* example: Example configuration.
(line 6)
* frame type: The UDP tunnel. (line 6)
* GraphDumpFile: Main configuration variables.
(line 73)
* Hostnames: Main configuration variables.
(line 81)
* hub: Main configuration variables.
(line 122)
* ID: Authentication protocol.
(line 10)
* IndirectData: Host configuration variables.
(line 27)
* INTERFACE: Scripts. (line 58)
* Interface: Main configuration variables.
(line 91)
* IRC: Contact information. (line 9)
* key generation: Generating keypairs. (line 6)
* KEY_CHANGED: The meta-protocol. (line 64)
* KeyExpire: Main configuration variables.
(line 127)
* libraries: Libraries. (line 6)
* license: OpenSSL. (line 36)
* lzo: lzo. (line 6)
* MACExpire: Main configuration variables.
(line 133)
* MACLength: Host configuration variables.
(line 35)
* meta-protocol: The meta-connection. (line 18)
* META_KEY: Authentication protocol.
(line 10)
* Mode: Main configuration variables.
(line 99)
* multiple networks: Multiple networks. (line 6)
* NAME: Scripts. (line 52)
* Name: Main configuration variables.
(line 138)
* netmask: Network interfaces. (line 34)
* NETNAME: Scripts. (line 49)
* netname: Multiple networks. (line 6)
* Network Administrators Guide: Configuration introduction.
(line 15)
* NODE: Scripts. (line 62)
* OpenSSL: OpenSSL. (line 6)
* options: Runtime options. (line 9)
* PEM format: Host configuration variables.
(line 60)
* PING: The meta-protocol. (line 89)
* PingInterval: Main configuration variables.
(line 143)
* PingTimeout: Main configuration variables.
(line 147)
* platforms: Supported platforms. (line 6)
* PMTU: Host configuration variables.
(line 40)
* PMTUDiscovery: Host configuration variables.
(line 43)
* PONG: The meta-protocol. (line 89)
* Port: Host configuration variables.
(line 48)
* port numbers: Other files. (line 17)
* PriorityInheritance: Main configuration variables.
(line 153)
* private: Virtual Private Networks.
(line 10)
* PrivateKey: Main configuration variables.
(line 158)
* PrivateKeyFile: Main configuration variables.
(line 164)
* PublicKey: Host configuration variables.
(line 52)
* PublicKeyFile: Host configuration variables.
(line 55)
* release: Supported platforms. (line 14)
* REMOTEADDRESS: Scripts. (line 67)
* REMOTEPORT: Scripts. (line 70)
* REQ_KEY: The meta-protocol. (line 64)
* requirements: Libraries. (line 6)
* router: Main configuration variables.
(line 102)
* runtime options: Runtime options. (line 9)
* scalability: tinc. (line 19)
* scripts: Scripts. (line 6)
* server: How connections work.
(line 18)
* signals: Signals. (line 6)
* SUBNET: Scripts. (line 74)
* Subnet: Host configuration variables.
(line 67)
* SVPN: Security. (line 11)
* switch: Main configuration variables.
(line 111)
* TCP: The meta-connection. (line 10)
* TCPonly: Host configuration variables.
(line 90)
* TINC: Security. (line 6)
* tinc: Introduction. (line 6)
* tinc-down: Scripts. (line 18)
* tinc-up <1>: Network interfaces. (line 19)
* tinc-up: Scripts. (line 10)
* tincd: tinc. (line 14)
* traditional VPNs: tinc. (line 19)
* tunifhead: Main configuration variables.
(line 62)
* TunnelServer: Main configuration variables.
(line 172)
* tunnohead: Main configuration variables.
(line 56)
* UDP <1>: Encryption of network packets.
(line 12)
* UDP: The UDP tunnel. (line 30)
* Universal tun/tap: Configuration of Linux kernels.
(line 6)
* virtual: Virtual Private Networks.
(line 18)
* virtual network device: The UDP tunnel. (line 6)
* VPN: Virtual Private Networks.
(line 6)
* vpnd: tinc. (line 6)
* website: Contact information. (line 6)
* zlib: zlib. (line 6)

Tag Table:
Node: Top861
Node: Introduction1160
Node: Virtual Private Networks1970
Node: tinc3695
Node: Supported platforms5222
Node: Preparations5920
Node: Configuring the kernel6176
Node: Configuration of Linux kernels6585
Node: Configuration of FreeBSD kernels7440
Node: Configuration of OpenBSD kernels7830
Node: Configuration of NetBSD kernels8438
Node: Configuration of Solaris kernels8843
Node: Configuration of Darwin (MacOS/X) kernels9504
Node: Configuration of Windows10207
Node: Libraries10721
Node: OpenSSL11109
Node: zlib13385
Node: lzo14214
Node: Installation15001
Node: Building and installing tinc16016
Node: Darwin (MacOS/X) build environment16675
Node: Cygwin (Windows) build environment17243
Node: MinGW (Windows) build environment17831
Node: System files18355
Node: Device files18620
Node: Other files19036
Node: Configuration19649
Node: Configuration introduction19960
Node: Multiple networks21233
Node: How connections work22659
Node: Configuration files23881
Node: Main configuration variables24888
Node: Host configuration variables32721
Node: Scripts37286
Node: How to configure39965
Node: Generating keypairs41228
Node: Network interfaces41727
Node: Example configuration43575
Node: Running tinc48887
Node: Runtime options49477
Node: Signals51484
Node: Debug levels52553
Node: Solving problems53489
Node: Error messages54919
Node: Sending bug reports59241
Node: Technical information60193
Node: The connection60424
Node: The UDP tunnel60736
Node: The meta-connection63797
Node: The meta-protocol65266
Node: Security70275
Node: Authentication protocol71405
Node: Encryption of network packets76409
Node: Security issues77782
Node: Platform specific information79399
Node: Interface configuration79627
Node: Routes81526
Node: About us83442
Node: Contact information83617
Node: Authors84021
Node: Concept Index84447

End Tag Table
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