\input texinfo @c -*-texinfo-*-
+@c $Id: tinc.texi,v 1.8.4.11 2001/01/06 20:02:21 guus Exp $
@c %**start of header
@setfilename tinc.info
@settitle tinc Manual
This is the info manual for tinc, a Virtual Private Network daemon.
-Copyright 1998 Ivo Timmermans <itimmermans@@bigfoot.com>
+Copyright @copyright{} 1998,199,2000 Ivo Timmermans
+<itimmermans@@bigfoot.com>, Guus Sliepen <guus@@sliepen.warande.net> and
+Wessel Dankers <wsl@@nl.linux.org>.
- 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.
+$Id: tinc.texi,v 1.8.4.11 2001/01/06 20:02:21 guus Exp $
- 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.
+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.
@end ifinfo
@titlepage
@title tinc Manual
@subtitle Setting up a Virtual Private Network with tinc
-@author Ivo Timmermans <itimmermans@@bigfoot.com>
+@author Ivo Timmermans and Guus Sliepen
@page
@vskip 0pt plus 1filll
-Copyright @copyright{} 1998 Ivo Timmermans <itimmermans@@bigfoot.com>
+@cindex copyright
+Copyright @copyright{} 1998,1999,2000 Ivo Timmermans
+<itimmermans@@bigfoot.com>, Guus Sliepen <guus@@sliepen.warande.net> and
+Wessel Dankers <wsl@@nl.linux.org>.
+
+$Id: tinc.texi,v 1.8.4.11 2001/01/06 20:02:21 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 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.
+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.
@end titlepage
@menu
* Introduction:: Introduction
-* Configuring a Linux system:: Before compiling tinc
-* Installing tinc::
+* Installing tinc - preparations::
+* Installing tinc - installation::
* Configuring tinc::
* Running tinc::
* Technical information::
* Concept Index:: All used terms explained
@end menu
+
+@contents
+
@c ==================================================================
-@node Introduction, Configuring a Linux system, Top, Top
+@node Introduction, Installing tinc - preparations, Top, Top
@chapter Introduction
-@c straight from the www page
-
+@cindex tinc
tinc is a Virtual Private Network (VPN) daemon that uses tunneling and
encryption to create a secure private network between hosts on the
Internet.
This tunneling 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
+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::
@end menu
@c ==================================================================
@node VPNs, tinc, Introduction, Introduction
@section Virtual Private Networks
+@cindex VPN
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
+by a few elected computers that participate. This goal is achievable in
more than just one way.
@cindex private
-For instance, a VPN can consist of a single stand-alone ethernet LAN. Or
-even two computers hooked up using a null-modem cable@footnote{Though
-discuss-able, I think it qualifies as a VPN.}. In these cases, it is
-obvious that the network is @emph{private}. But there is another type
-of VPN, the type tinc was made for.
+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 @emph{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.
+
+@cindex virtual
+This problem can be solved by using @emph{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
+each other. 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.
+
+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.
@cindex virtual
tinc uses normal IP datagrams to encapsulate data that goes over the VPN
-network link. In this case it's also clear that the network is
+network link. In this case it's also clear that the network is
@emph{virtual}, because no direct network link has to exist between to
participants.
-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
+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.
@c ==================================================================
-@node tinc, , VPNs, Introduction
+@node tinc, Supported platforms, VPNs, Introduction
@section tinc
+@cindex vpnd
+@cindex ethertap
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
+Guus' idea. He wrote a simple implementation (about 50 lines of C) that
used the @emph{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 @samp{vpnd}.
+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 @samp{vpnd}.
Since then, a lot has changed---to say the least.
runtime-configurable---in short, it has become a full-fledged
professional package.
-A lot can---and will be---changed. I have a few things that I'd 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
+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
+Meanwhile, we're always open-minded towards new ideas. And we're
available too.
@c ==================================================================
-@node Configuring a Linux system, Installing tinc, Introduction, Top
-@chapter Configuring a Linux system
+@node Supported platforms, , tinc, Introduction
+@section Supported platforms
+
+tinc has been verified to work under Linux, FreeBSD and Solaris, with
+various hardware architectures. These are the three platforms
+that are supported by the universial TUN/TAP device driver, so if
+support for other operating systems is added to this driver, perhaps
+tinc will run on them as well. Without this 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:
+@uref{http://tinc.nl.linux.org/platforms.html}.
+
+
+@c ==================================================================
+@subsection 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 that is provided in the standard kernel
+since version 2.1.60, so anything above that (2.2.x, 2.3.x, and 2.4.0)
+kernel version is able to support tinc.
+
+
+@c ==================================================================
+@subsection FreeBSD
+
+tinc on FreeBSD relies on the universial TUN/TAP driver for its data
+acquisition from the kernel. Therefore, tinc suports the same platforms
+as this driver. These are: FreeBSD 3.x, 4.x, 5.x.
+
+
+@c ==================================================================
+@subsection Solaris
+
+tinc on Solaris relies on the universial TUN/TAP driver for its data
+acquisition from the kernel. Therefore, tinc suports the same platforms
+as this driver. These are: Solaris, 2.1.x.
+
+
+@c
+@c
+@c
+@c
+@c
+@c
+@c Preparing your system
+@c
+@c
+@c
+@c
+@c
+
+@c ==================================================================
+@node Installing tinc - preparations, Installing tinc - installation, Introduction, Top
+@chapter Installing tinc: preparations
-This chapter contains information on how a Linux system is configured
-for the use of tinc.
+This chapter contains information on how to prepare your system to
+support tinc.
@menu
* Configuring the kernel::
-* Files Needed::
-* Setting up the devices::
+* Libraries::
@end menu
@c ==================================================================
-@node Configuring the kernel, Files Needed, Configuring a Linux system, Configuring a Linux system
+@node Configuring the kernel, Libraries, Installing tinc - preparations, Installing tinc - preparations
@section 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'. You need both these devices.
+
+If you can install these devices in a similar manner, you may skip this
+section.
+
+@menu
+* Configuration of the Linux kernel::
+* Configuration of the FreeBSD kernel::
+* Configuration of the Solaris kernel::
+@end menu
+
+
+@c ==================================================================
+@node Configuration of the Linux kernel, Configuration of the FreeBSD kernel, Configuring the kernel, Configuring the kernel
+@subsection Configuring the Linux kernel
+
Since this particular implementation only runs on 2.1 or higher Linux
-kernels, you should grab one (2.2 is current at this time). A 2.0 port
+kernels, you should grab one (2.2 is current at this time). A 2.0 port
is not really possible, unless someone tells me someone ported the
ethertap and netlink devices back to 2.0.
If you are unfamiliar with the process of configuring and compiling a
new kernel, you should read the
@uref{http://howto.linuxberg.com/LDP/HOWTO/Kernel-HOWTO.html, Kernel
-HOWTO} first. Do that now!
+HOWTO} first. Do that now!
-Here are the options you have to turn on/off when configuring a new
+Here are the options you have to turn on when configuring a new
kernel.
+For kernel 2.2.x:
+
@example
Code maturity level options
[*] Prompt for development and/or incomplete code/drivers
<*> Ethertap network tap
@end example
-Any other options not mentioned here are not relevant to tinc. If you
+Note that 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.
+
+For kernel 2.3.x and 2.4.x:
+
+@example
+Code maturity level options
+[*] Prompt for development and/or incomplete code/drivers
+Networking options
+[*] Kernel/User netlink socket
+<*> Netlink device emulation
+Network device support
+<*> Universal TUN/TAP device driver support
+@end example
+
+
+Any other options not mentioned here are not relevant to tinc. If you
decide to build any of these as dynamic kernel modules, it's a good idea
to add these lines to @file{/etc/modules.conf}.
alias char-major-36 netlink_dev
@end example
+If you have a 2.4-pre kernel, you can choose both the TUN/TAP driver and
+the `Ethertap network tap' device. This latter is marked obsolete,
+because the universal TUN/TAP driver is a newer implementation that is
+supposed to be used in favour of ethertap. For tinc, it doesn't really
+matter which one you choose; based on the device file name, tinc will make
+the right choice about what protocol to use. However, chances are that
+although you can choose the obsolote ethertap driver, it will not function
+at all. The TUN/TAP driver is the safe choice.
+
Finally, after having set up other options, build the kernel and boot
-it. Unfortunately it's not possible to insert these modules in a running
-kernel.
+it. Unfortunately it's not possible to insert these modules in a
+running kernel.
+
+
+@c ==================================================================
+@node Configuration of the FreeBSD kernel, Configuration of the Solaris kernel, Configuration of the Linux kernel, Configuring the kernel
+@subsection Configuring the FreeBSD kernel
+
+This section will contain information on how to configure your FreeBSD
+kernel to support the universal TUN/TAP device. For 5.0 and 4.1
+systems, this is included in the kernel configuration, for earlier
+systems (4.0 and 3.x), you need to install the universal TUN/TAP driver
+yourself.
+
+Unfortunately somebody still has to write the text.
+
+
+@c ==================================================================
+@node Configuration of the Solaris kernel, , Configuration of the FreeBSD kernel, Configuring the kernel
+@subsection Configuring the Solaris kernel
+
+This section will contain information on how to configure your Solaris
+kernel to support the universal TUN/TAP device. You need to install
+this driver yourself.
+
+Unfortunately somebody still has to write the text.
+
+
+@c ==================================================================
+@node Libraries, , Configuring the kernel, Installing tinc - preparations
+@section Libraries
+
+@cindex requirements
+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::
+@end menu
@c ==================================================================
-@node Files Needed, Setting up the devices, Configuring the kernel, Configuring a Linux system
-@section Files Needed
+@node OpenSSL, , Libraries, Libraries
+@subsection OpenSSL
-@subsubheading Device files
+@cindex OpenSSL
+For all cryptography-related functions, tinc uses the functions provided
+by the OpenSSL library. We recommend using version 0.9.5 or 0.9.6 of
+this library. Other versions may also work, but we can guarantee
+nothing.
+
+If this library is not installed, you wil get an error when configuring
+tinc for build. Support for running tinc without having OpenSSL
+installed @emph{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 @url{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.
+
+@example
+--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)
+@end example
+
+
+@subsubheading License
+
+Since the license under which OpenSSL is distributed is not directly
+compatible with the terms of the GNU GPL
+@uref{http://www.openssl.org/support/faq.html#LEGAL2}, therefore we
+include an addition to the GPL (see also the file COPYING.README):
+
+@quotation
+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.
+@end quotation
+
+
+@c
+@c
+@c
+@c Installing tinc
+@c
+@c
+@c
+@c
+
+@c ==================================================================
+@node Installing tinc - installation, Configuring tinc, Installing tinc - preparations, Top
+@chapter Installing tinc: installation
+
+If you use Redhat or 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 don't run either of these systems, 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
+@uref{http://tinc.nl.linux.org/download.html, download page}, 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 @file{INSTALL}, which is
+included in the source distribution.
+
+@menu
+* Building tinc::
+* System files::
+* Interfaces::
+@end menu
+
+
+@c ==================================================================
+@node Building tinc, System files, Installing tinc - installation, Installing tinc - installation
+@section Building tinc
+
+Detailed instructions on configuring the source and building tinc can be
+found in the file called @file{INSTALL}.
+
+
+@c ==================================================================
+@node System files, Interfaces, Building tinc, Installing tinc - installation
+@section 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::
+@end menu
+
+
+@c ==================================================================
+@node Device files, Other files, System files, System files
+@subsection 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 the universal TUN/TAP driver, you have to create the
+following device files (unless they already exist):
+
+@example
+mknod -m 600 /dev/... c .. ..
+chown 0.0 /dev/...
+@end example
+
+If you want to have more devices, the device numbers will be .. .. ...
+
+If you use Linux, and you run the new 2.4 kernel using the devfs
+filesystem, then the tap device will be automatically generated as
+@file{/dev/netlink/tap0}.
+
+If you use Linux and have kernel 2.2.x, you have to make the ethertap
+devices:
+
@example
mknod -m 600 /dev/tap0 c 36 16
chown 0.0 /dev/tap0
@end example
-The permissions now will 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.
+Any further ethertap devices have minor device number 16 through 31.
-If you want to, you may also create more device files, which would be
-numbered 0...15, with minor device numbers 16...31. They all should be
-owned by root and have permission 600.
+@c ==================================================================
+@node Other files, , Device files, System files
+@subsection Other files
@subsubheading @file{/etc/networks}
You may add a line to @file{/etc/networks} so that your VPN will get a
-symbolic name. For example:
+symbolic name. For example:
@example
myvpn 10.0.0.0
@end example
+This has nothing to do with the MyVPNIP configuration variable that will be
+discussed later, it is only to make the output of the route command more
+legible.
@subsubheading @file{/etc/services}
-You may add this line to @file{/etc/services}. The effect is that you
-may supply a @samp{tinc} as a valid port number to some programs. The
+You may add this line to @file{/etc/services}. The effect is that you
+may supply a @samp{tinc} as a valid port number to some programs. The
number 655 is registered with the IANA.
@example
@c ==================================================================
-@node Setting up the devices, , Files Needed, Configuring a Linux system
-@section Setting up the devices
+@node Interfaces, , System files, Installing tinc - installation
+@section Interfaces
Before you can start transmitting data over the tinc tunnel, you must
set up the ethertap network devices.
First, decide which IP addresses you want to have associated with these
-devices, and what network mask they must have. You also need these
-numbers when you are going to configure tinc itself. @xref{Configuring
+devices, and what network mask they must have. You also need these
+numbers when you are going to configure tinc itself. @xref{Configuring
tinc}.
It doesn't matter much which part you do first, setting up the network
-devices or configure tinc. But they both have to be done before you try
+devices or configure tinc. But they both have to be done before you try
to start a tincd.
The actual setup of the ethertap device is quite simple, just repeat
after me:
@example
-ifconfig tap@emph{n} hw ether fe:fd:@emph{xx}:@emph{xx}:@emph{xx}:@emph{xx}
+ifconfig tap@emph{n} hw ether fe:fd:00:00:00:00
@end example
-The @emph{n} here is the number of the ethertap device you want to
-use. It should be the same @emph{n} as the one you use for
-@file{/dev/tap@emph{n}}. The @emph{xx}s are four hexadecimal numbers
-(0--ff). With previous versions of tincd, it didn't matter what they
-were. But newer kernels require properly set up ethernet addresses.
-In fact, the old behavior was wrong. It is required that the @emph{xx}s
-match MyOwnVPNIP.
+@cindex MAC address
+@cindex hardware address
+@strong{Note:} Since version 1.0pre3, all interface addresses are set to
+this address, whereas previous versions required the MAC to match the
+actual IP address.
+
+@cindex ifconfig
+To activate the device, you have to assign an IP address to it. To set
+an IP address @emph{IP} with network mask @emph{mask}, do the following:
@example
-ifconfig tap@emph{n} @emph{IP} netmask @emph{mask}
+ifconfig tap@emph{n} @emph{xx}.@emph{xx}.@emph{xx}.@emph{xx} netmask @emph{mask}
@end example
-This will activate the device with an IP address @emph{IP} with network
-mask @emph{mask}.
+@cindex netmask
+The netmask is the mask of the @emph{entire} VPN network, not just your
+own subnet. It is the same netmask you will have to specify with the
+VpnMask configuration variable.
-
-@c ==================================================================
-@node Installing tinc, Configuring tinc, Configuring a Linux system, Top
-@chapter Installing tinc
-
-First download it. This is the
-@uref{http://tinc.nl.linux.org/download.html, download
-page}, which has the checksums of these files listed; you may wish to
-check these with md5sum before continuing.
-
-tinc comes in a handy 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 @file{INSTALL}, which is
-included in the source distribution.
+@c
+@c
+@c
+@c
+@c Configuring tinc
+@c
+@c
+@c
+@c
@c ==================================================================
-@node Configuring tinc, Running tinc, Installing tinc, Top
+@node Configuring tinc, Running tinc, Installing tinc - installation, Top
@chapter Configuring tinc
@menu
* Example::
@end menu
-
@c ==================================================================
@node Multiple networks, How connections work, Configuring tinc, Configuring tinc
@section Multiple networks
However, in its default form, you will soon notice that you can't use
two different configuration files without the -c option.
-We have thought of another way of dealing with this: network names. This
+We have thought of another way of dealing with this: network names. This
means that you call tincd with the -n argument, which will assign a name
to this daemon.
The effect of this is that the daemon will set its configuration
``root'' to /etc/tinc/nn/, where nn is your argument to the -n
-option. You'll notice that it appears in syslog as ``tinc.nn''.
+option. You'll notice that it appears in syslog as ``tinc.nn''.
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
+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/nn/; the configuration file should be /etc/tinc/tinc.conf,
and the passphrases are now expected to be in /etc/tinc/passphrases/.
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
+it will be so much clearer whom your daemon talks to. Hence, we will
assume that you use it.
Before going on, first a bit on how tinc sees connections.
When tinc starts up, it reads in the configuration file and parses the
-command-line options. If it sees a `ConnectTo' value in the file, it
-will try to connect to it, on the given port. If this fails, tinc exits.
+command-line options. If it sees a `ConnectTo' value in the file, it
+will try to connect to it, on the given port. If this fails, tinc exits.
@c ==================================================================
@end example
The variable names are case insensitive, and any spaces, tabs, newlines
-and carriage returns are ignored. Note: it is not required that you put
+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; required directives are
+given in @strong{bold}.
+
@menu
-* Variables::
+* Main configuration variables::
+* Host configuration variables::
+* How to configure::
@end menu
-@c ==================================================================
-@node Variables, , Configuration file, Configuration file
-@subsection Variables
-Here are all valid variables, listed in alphabetical order:
+@c ==================================================================
+@node Main configuration variables, Host configuration variables, Configuration file, Configuration file
+@subsection Main configuration variables
-@c straight from the manpage
@table @asis
-@item AllowConnect = (yes|no)
-If set to yes, anyone may try to connect to you. If you set this to no,
-no incoming connections will be accepted. This does not affect the
-outgoing connections.
+@item @strong{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.
+
+@item 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.
+
+@item Interface = <device>
+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.
+
+@item InterfaceIP = <local address>
+If your computer has more than one IP address on a single interface (for
+example if you are running virtual hosts), tinc will by default listen
+on all of them for incoming connections. It is possible to bind tinc to
+a single IP address with this variable. It is still possible to listen
+on several interfaces at the same time though, if they share the same IP
+address.
+
+@item 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.
+
+@item @strong{Name = <name>}
+This is a symbolic name for this connection. It can be anything
+
+@item PingTimeout = <seconds> (5)
+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.
-@item ConnectPort = port
+@item PrivateKey = <key>
+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.
+
+@item PrivateKeyFile = <path>
+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 exactly @strong{one of the above two options} must be specified.
+
+@item TapDevice = <device> (/dev/tap0)
+The ethertap device to use. Note that you can only use one device per
+daemon. The info pages of the tinc package contain more information
+about configuring an ethertap device for Linux.
+
+@item VpnMask = <mask>
+The mask that defines the scope of the entire VPN. This option is not
+used by the tinc daemon itself, but can be used by startup scripts to
+configure the ethertap devices correctly.
+@end table
+
+
+@c ==================================================================
+@node Host configuration variables, How to configure, Main configuration variables, Configuration file
+@subsection Host configuration variables
+
+@table @asis
+@item @strong{Address = <IP address|hostname>}
+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.
+
+@item 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.
+
+@item 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) or hexadecimal (prefixed with 0x). port is the port
+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.
-@item ConnectTo = (IP address|hostname)
-Specifies which host to connect to on startup. If the ConnectPort
-variable is omitted, then tinc will try to connect to port 655.
+@item PublicKey = <key>
+This is the RSA public key for this host.
-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. Only the initiator of a
-tinc VPN should need this.
+@item PublicKeyFile = <path>
+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.
-@item ListenPort = port
-Listen on local port port. The computer connecting to this daemon should
-use this number as the argument for his ConnectPort. Again, the
-default is 655.
+Note that exactly @strong{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.
-@item MyOwnVPNIP = local address[/maskbits]
-The local address is the number that the daemon will propagate to
-other daemons on the network when it is identifying itself. Hence this
-will be the file name of the passphrase file that the other end expects
-to find the passphrase in.
+@item Subnet = <IP address/maskbits>
+This is the subnet range of all IP addresses that will be accepted by
+the host that defines it.
-The local address is the IP address of the tap device, not the real IP
-address of the host running tincd. Due to changes in recent kernels, it
-is also necessary that you make the ethernet (also known as MAC) address
-equal to the IP address (see the example).
+The range must be contained in the IP address range of the tap device,
+not the real IP address of the host running tincd.
-maskbits is the number of bits set to 1 in the netmask part.
+maskbits 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
+@uref{ftp://ftp.isi.edu/in-notes/rfc1519.txt, RFC1519}
-@item MyVirtualIP = local address[/maskbits]
-This is an alias for MyOwnVPNIP.
+@item 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. @emph{This is
+experimental code, try this at your own risk. It may not work at all.}
+@end table
-@item Passphrases = directory
-The directory where tinc will look for passphrases when someone tries to
-connect. Please see the manpage for genauth(8) for more information
-about passphrases as used by tinc.
-@item PingTimeout = number
-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.
+@c ==================================================================
+@node How to configure, , Host configuration variables, Configuration file
+@subsection How to configure
-@item TapDevice = device
-The ethertap device to use. Note that you can only use one device per
-daemon. The info pages of the tinc package contain more information
-about configuring an ethertap device for Linux.
+@subsubheading Step 1. Creating the key files
+
+For each host, you have to create a pair of RSA keys. One key is your
+private key, which is only known to you. The other one is the public
+key, which you should copy to all hosts wanting to authenticate to you.
+
+
+@subsubheading Step 2. Configuring each host
+For every host in the VPN, you have to create two files. First there is
+the main configuration file, @file{/etc/tinc/vpn-name/tinc.conf}. In
+this file there should at least be three directives:
+
+@table @samp
+@item Name
+You should fill in the name of this host (or rather, the name of this
+leaf of the VPN). It can be called after the hostname, the physical
+location, the department, or the name of one of your boss' pets. It can
+be anything, as long as all these names are unique across the entire
+VPN.
+
+@item PrivateKey
+Fill in the full pathname to the file that contains the private RSA key.
+
+@item ConnectTo
+This is the name of the host that you want to connect to (not a DNS
+name, rather the name that is given with the Name parameter in that
+hosts tinc.conf). This is the upstream connection. If your computer is
+a central node, you might want to leave this out to make it stay idle
+until someone connects to it.
+@end table
+
+@cindex host configuration file
+Then you should create a file with the name you gave yourself in
+tinc.conf (the `Name' parameter), located in
+@file{/etc/tinc/vpn-name/hosts/}. In this file, which we call the
+`@emph{host configuration file}', only one variable is required:
+
+@table @samp
+@item Subnet
+The IP range that this host accepts as being `local'. All packets with
+a destination address that is within this subnet will be sent to us.
@end table
+@subsubheading Step 3. Bringing it all together
+
+Now for all hosts that you want to create a direct connection to, -- you
+connect to them or they connect to you -- you get a copy of their host
+configuration file and their public RSA key.
+
+For each host configuration file, you add two variables:
+
+@table @samp
+@item Address
+Enter the IP address or DNS hostname for this host. This is only needed
+if you connect to this host.
+
+@item PublicKey
+Put the full pathname to this hosts public RSA key here.
+@end table
+
+When you did this, you should be ready to create your first connection.
+Pay attention to the system log, most errors will only be visible
+there. If you get an error, you can check @ref{Error messages}.
+
+
@c ==================================================================
@node Example, , Configuration file, Configuring tinc
@section Example
-Imagine the following situation. An A-based company wants to connect
-three branch offices in B, C and D using the internet. All four offices
+
+@cindex example
+Imagine the following situation. An A-based 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
+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.
@example
@end example
``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
+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 LAN of the office. This could be the same as the interface
-that leads to the internet.
+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.
@subsubheading For A
@emph{A} would be configured like this:
@example
-ifconfig tap0 hw ether fe:fd:0a:01:36:01
+#ifconfig eth0 10.1.54.1 netmask 255.255.0.0 broadcast 10.1.255.255
+ifconfig tap0 hw ether fe:fd:00:00:00:00
ifconfig tap0 10.1.54.1 netmask 255.0.0.0
-ifconfig eth0 10.1.54.1 netmask 255.255.0.0 broadcast 10.1.255.255
@end example
and in /etc/tinc/tinc.conf:
@example
-TapDevice = /dev/tap0
-MyVirtualIP = 10.1.54.1/16
+Name = A
+PrivateKey = /etc/tinc/A.priv
+VpnMask = 255.0.0.0
@end example
+On all hosts, /etc/tinc/hosts/A contains:
+
+@example
+Subnet = 10.1.0.0/16
+Address = 1.2.3.4
+PublicKey = /etc/tinc/hosts/A.pub
+@end example
+
+
@subsubheading For B
@example
-ifconfig tap0 hw ether fe:fd:0a:02:01:0c
+#ifconfig eth0 10.2.43.8 netmask 255.255.0.0 broadcast 10.2.255.255
+ifconfig tap0 hw ether fe:fd:00:00:00:00
ifconfig tap0 10.2.1.12 netmask 255.0.0.0
-ifconfig eth0 10.2.43.8 netmask 255.255.0.0 broadcast 10.2.255.255
@end example
and in /etc/tinc/tinc.conf:
@example
-TapDevice = /dev/tap0
-MyVirtualIP = 10.2.1.12/16
-ConnectTo = 1.2.3.4
-AllowConnect = no
+Name = B
+ConnectTo = A
+PrivateKey = /etc/tinc/B.priv
+VpnMask = 255.0.0.0
@end example
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
+same as on the tap0 device. Also, ConnectTo is given so that no-one can
connect to this node.
+On all hosts, /etc/tinc/hosts/B:
+
+@example
+Subnet = 10.2.0.0/16
+Address = 2.3.4.5
+PublicKey = /etc/tinc/hosts/B.pub
+@end example
+
+
@subsubheading For C
@example
-ifconfig tap0 hw ether fe:fd:0a:03:45:fe
+#ifconfig eth0 10.3.69.254 netmask 255.255.0.0 broadcast 10.3.255.255
+ifconfig tap0 hw ether fe:fd:00:00:00:00
ifconfig tap0 10.3.69.254 netmask 255.0.0.0
-ifconfig eth0 10.3.69.254 netmask 255.255.0.0 broadcast 10.3.255.255
@end example
and in /etc/tinc/A/tinc.conf:
@example
-MyVirtualIP = 10.3.69.254/16
-ConnectTo = 1.2.3.4
-ListenPort = 2000
+Name = C
+ConnectTo = A
+TapDevice = /dev/tap1
+VpnMask = 255.0.0.0
@end example
C already has another daemon that runs on port 655, so they have to
-reserve another port for tinc. They also use the netname to distinguish
-between the two. tinc is started with `tincd -n A'.
+reserve another port for tinc. It can connect to other tinc daemons on
+the regular port though, so no ConnectPort variable is needed. They
+also use the netname to distinguish between the two. tinc is started
+with `tincd -n A'.
+
+On all hosts, /etc/tinc/hosts/C:
+
+@example
+Subnet = 10.3.0.0/16
+Port = 2000
+PublicKey = /etc/tinc/hosts/C.pub
+@end example
+
@subsubheading For D
@example
+#ifconfig tap0 10.4.3.32 netmask 255.255.0.0 broadcast 10.4.255.255
ifconfig tap0 hw ether fe:fd:0a:04:03:20
ifconfig tap0 10.4.3.32 netmask 255.0.0.0
-ifconfig tap0 10.4.3.32 netmask 255.255.0.0 broadcast 10.4.255.255
@end example
and in /etc/tinc/tinc.conf:
MyVirtualIP = 10.4.3.32/16
ConnectTo = 3.4.5.6
ConnectPort = 2000
-AllowConnect = no
+VpnMask=255.0.0.0
@end example
D will be connecting to C, which has a tincd running for this network on
-port 2000. Hence they need to put in a ConnectPort.
+port 2000. Hence they need to put in a ConnectPort, but it doesn't need
+to have a different ListenPort.
-@subsubheading Authentication
+@subsubheading Key files
-A, B, C and D all generate a passphrase with genauth 2048, the output is
-stored in /etc/tinc/passphrases/local, except for C, where it should be
-/etc/tinc/A/passphrases/local.
+A, B, C and D all have generate a public key with tincd -K, the output is
+stored in /etc/tinc/hosts/X.pub (where X is A, B or D), except for C,
+who stored it in /etc/tinc/A/hosts/C.pub.
-A stores a copy of B's passphrase in /etc/tinc/passphrases/10.2.0.0
+A stores a copy of B's public key in /etc/tinc/hosts/B.pub
-A stores a copy of C's passphrase in /etc/tinc/passphrases/10.3.0.0
+A stores a copy of C's public key in /etc/tinc/hosts/C.pub
-B stores a copy of A's passphrase in /etc/tinc/passphrases/10.1.0.0
+B stores a copy of A's public key in /etc/tinc/hosts/A.pub
-C stores a copy of A's passphrase in /etc/tinc/A/passphrases/10.1.0.0
+C stores a copy of A's public key in /etc/tinc/A/hosts/A.pub
-C stores a copy of D's passphrase in /etc/tinc/A/passphrases/10.4.0.0
+C stores a copy of D's public key in /etc/tinc/A/hosts/D.pub
-D stores a copy of C's passphrase in /etc/tinc/passphrases/10.3.0.0
+D stores a copy of C's public key in /etc/tinc/hosts/C.pub
@subsubheading Starting
-A has to start their tincd first. Then come B and C, where C has to
+A has to start their tincd first. Then come B and C, where C has to
provide the option `-n A', because they have more than one tinc
-network. Finally, D's tincd is started.
+network. Finally, D's tincd is started.
@chapter Running tinc
Running tinc isn't just as easy as typing `tincd' and hoping everything
-will just work out the way you wanted. Instead, the use of tinc is a
+will just work out the way you wanted. Instead, the use of tinc is a
project that involves trust relations and more than one computer.
@menu
* Managing keys::
* Runtime options::
+* Error messages::
@end menu
@node Managing keys, Runtime options, Running tinc, Running tinc
@section Managing keys
-Before attempting to start tinc, you have to create passphrases. When
-tinc tries to make a connection, it exchanges some sensitive
-data. Before doing so, it likes to know if the other end is
+Before attempting to start tinc, you have to create public/private keypairs.
+When tinc tries to make a connection, it exchanges some sensitive
+data. Before doing so, it likes to know if the other end is
trustworthy.
-To do this, both ends must have some knowledge about the other. In the
-case of tinc this is the authentication passphrase.
-
-This passphrase is a number, which is chosen at random. This number is
-then sent to the other computers which want to talk to us directly. To
-avoid breaking security, this should be done over a known secure channel
-(such as ssh or similar).
+To do this, both ends must have some knowledge about the other. In the
+case of tinc this is the public keys.
-All passphrases are stored in the passphrases directory, which is
-normally /etc/tinc/nn/passphrases/, but it may be changed using the
-`Passphrases' option in the config file.
+To generate a public/private keypair, run `tincd -n vpn-name -K<bits>'.
+<bits> is optional, you can use it to specify the length of the keys.
+The length of the public/private keypairs
+should be at least 1024 for reasonable security (reasonable being good enough
+to keep the NSA busy for a few weeks).
-To generate a passphrase, run `genauth'. genauth takes one argument,
-which is the length of the passphrase in bits. The length of the
-passphrase should be in the range 1024--2048 for a key length of 128
-bits. genauth creates a random number of the specified length, and puts
-it to stdout.
+Every computer that wants to participate in the VPN should do this. The
+public keyfile should get the name of each tinc daemon and an extension .pub,
+and it should be stored in the hosts directory.
-Every computer that wants to participate in the VPN should do this, and
-store the output in the passphrases directory, in the file @file{local}.
-
-When every computer has his own local key, it should copy it to the
-computer that it wants to talk to directly. (i.e. the one it connects to
-during startup.) This should be done via a secure channel, because it is
-sensitive information. If this is not done securely, someone might break
-in on you later on.
-
-Those non-local passphrase files must have the name of the VPN IP
-address that they will advertise to you. For instance, if a computer
-tells us it likes to be 10.1.1.3 with netmask 255.255.0.0, the file
-should still be called 10.1.1.3, and not 10.1.0.0.
+When every computer has his own keys and configuration files, the files in the
+hosts directory should be exchanged with each other computer that it wants to
+talk to directly. Since only public keys are involved, you can safely do this
+via email, telnet or ftp, or even putting the contents on a public billboard.
@c ==================================================================
-@node Runtime options, , Managing keys, Running tinc
+@node Runtime options, Error messages, Managing keys, Running tinc
@section 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
+This list is a longer version of that in the manpage. The latter is
generated automatically, so may be more up-to-date.
+@cindex command line
+@cindex runtime options
+@cindex options
@c from the manpage
-@table @asis
-@item -c, --config=FILE
-Read configuration options from FILE. The default is
-@file{/etc/tinc/nn/tinc.conf}.
+@table @samp
+@item -c, --config=PATH
+Read configuration options from the directory PATH. The default is
+@file{/etc/tinc/nn/}.
@item -d
-Increase debug level. The higher it gets, the more gets
-logged. Everything goes via syslog.
+Increase debug level. The higher it gets, the more gets
+logged. Everything goes via syslog.
0 is the default, only some basic information connection attempts get
-logged. Setting it to 1 will log a bit more, still not very
-disturbing. With two -d's tincd will log protocol information, which can
-get pretty noisy. Three or more -d's will output every single packet
+logged. Setting it to 1 will log a bit more, still not very
+disturbing. With two -d's tincd will log protocol information, which can
+get pretty noisy. Three or more -d's will output every single packet
that goes out or comes in, which probably generates more data than the
packets themselves.
@item -k, --kill
-Attempt to kill a running tincd and exit. A TERM signal (15) gets sent
-to the daemon that his its PID in /var/run/tinc.nn.pid.
+Attempt to kill a running tincd and exit. A TERM signal (15) gets sent
+to the daemon that his its PID in /var/run/tinc.pid.
-Because it kills only one tincd, you should use -n here if you use it
-normally.
+Because it kills only one tinc daemon, you should use -n here if you
+started it that way. It will then read the PID from
+@file{/var/run/tinc.NETNAME.pid}.
@item -n, --net=NETNAME
-Connect to net NETNAME. @xref{Multiple networks}.
+Connect to net NETNAME. @xref{Multiple networks}.
-@item -t, --timeout=TIMEOUT
-Seconds to wait before giving a timeout. Should not be set too low,
-because every time tincd senses a timeout, it disconnects and reconnects
-again, which will cause unnecessary network traffic and log messages.
+@item -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.
@item --help
Display a short reminder of these runtime options and terminate.
@c ==================================================================
-@node Technical information, About us, Running tinc, Top
-@chapter Technical information
+@node Error messages, , Runtime options, Running tinc
+@section 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!
+
+@table @strong
+@item Could not open /dev/tap0: No such device
+@table @bullet
+@item You forgot to insmod netlink_dev.o
+@item You forgot to compile `Netlink device emulation' in the kernel
+@end table
+
+@item Can't write to tun/tap device: No such device
+@table @bullet
+@item You forgot to insmod tun.o
+@item You forgot to compile `Universal TUN/TAP driver' in the kernel
+@end table
+
+@item Packet with destination 1.2.3.4 is looping back to us!
+@table @bullet
+@item Something is not configured right. Packets are being sent out to the
+tap 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 netmask which is
+just as large as the netmask of the tap device. 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!
+@end table
+
+@item Network address and subnet mask do not match!
+@table @bullet
+@item The Subnet field must contain a network address. That means that
+the lower order bits of the address must be zero. For example, 192.168.1.1/24
+is wrong, you should use 192.168.1.0/24.
+@item If you only want to use one IP address, set the netmask to /32.
+@end table
+
+@item This is a bug: net.c:253: 24: Some error
+@table @bullet
+@item 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.
+@end table
+
+@item Error reading RSA key file `rsa_key.priv': No such file or directory
+@table @bullet
+@item 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.
+@end table
+
+@end table
@c ==================================================================
+@node Technical information, About us, Running tinc, Top
+@chapter Technical information
+
@menu
* The Connection::
* Security::
-* The Protocol::
@end menu
+
+@c ==================================================================
@node The Connection, Security, Technical information, Technical information
@section The basic philosophy of the way tinc works
-@cindex Connection
+@cindex connection
tinc is a daemon that takes VPN data and transmit that to another host
computer over the existing Internet infrastructure.
@cindex ethertap
@cindex frame type
The data itself is read from a character device file, the so-called
-@emph{ethertap} 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. Data to
+@emph{ethertap} 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. Data to
and from the device is formatted as if it were a normal ethernet card,
so a frame is preceded by two MAC addresses and a @emph{frame type}
field.
So when tinc reads an ethernet frame from the device, it determines its
-type. Right now, tinc can only handle Internet Protocol version 4 (IPv4)
-frames. Plans to support other protocols are being made. When tinc knows
+type. Right now, tinc can only handle Internet Protocol version 4 (IPv4)
+frames, because it needs IP headers for routing.
+Plans to support other protocols and switching instead of routing are being made.
+When tinc knows
which type of frame it has read, it can also read the source and
destination address from it.
-Now it is time that the frame gets encrypted. Currently the only
+Now it is time that the frame gets encrypted. Currently the only
encryption algorithm available is blowfish.
@cindex encapsulating
When the encryption is ready, 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
+packet to the destination computer. We do this by sending the packet
+over an UDP connection to the destination host. This is called
@emph{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 does a decrypt on the contents of the UDP datagram,
+in reverse. So it does a decrypt on the contents of the UDP datagram,
and it writes the decrypted information to its own ethertap device.
+To let the kernel on the receiving end accept the packet, the destination MAC
+address must match that of the tap interface. Because of the routing nature
+of tinc, ARP is not possible. tinc solves this by always overwriting the
+destination MAC address with fe:fd:0:0:0:0. That is also the reason why you must
+set the MAC address of your tap interface to that address.
+
@c ==================================================================
@node The Meta-connection, , Protocol Preview, The Connection
@subsection The meta-connection
-Having only a UDP connection available is not enough. Though suitable
+Having only an 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 encryption 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
+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.
@cindex data-protocol
@cindex meta-protocol
Like with any communication, we must have a protocol, so that everybody
-knows what everything stands for, an how he should react. Because we
-have two connections, we also have two protocols. The protocol used for
+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 ACK's sent instead of just one. Furthermore, if there would be
+a timeout, both TCP streams would sense the timeout, and both would
+start resending packets.
@c ==================================================================
-@node Security, The Protocol, The Connection, Technical information
+@node Security, , The Connection, Technical information
@section About tinc's encryption and other security-related issues.
@cindex tinc
@cindex Cabal
tinc got its name from ``TINC,'' short for @emph{There Is No Cabal}; the
alleged Cabal was/is an organization that was said to keep an eye on the
-entire Internet. As this is exactly what you @emph{don't} want, we named
+entire Internet. As this is exactly what you @emph{don't} want, we named
the tinc project after TINC.
@cindex SVPN
But in order to be ``immune'' to eavesdropping, you'll have to encrypt
-your data. Because tinc is a @emph{Secure} VPN (SVPN) daemon, it does
+your data. Because tinc is a @emph{Secure} VPN (SVPN) daemon, it does
exactly that: encrypt.
This chapter is a mixture of ideas, reasoning and explanation, please
don't take it too serious.
@menu
-* Key Management::
-* Authentication::
-* Protection::
-@end menu
-
-
-@c ==================================================================
-@node Key Management, Authentication, Security, Security
-@subsection Key Management
-@c FIXME: recheck
-
-@cindex Diffie-Hellman
-You can't just send a private encryption key to your peer, because
-somebody else might already be listening to you. So you'll have to
-negotiate over a shared but secret key. One way to do this is by using
-the ``Diffie-Hellman key exchange'' protocol
-(@uref{http://www.rsa.com/rsalabs/faq/html/3-6-1.html}). The idea is as
-follows.
-
-You have two participants A and B that want to agree over a shared
-secret encryption key. Both parties have some large prime number p and a
-generator g. These numbers may be known to the outside world, and hence
-may be included in the source distribution.
-
-@cindex secret key
-Both parties then generate a secret key. A generates a, and computes g^a
-mod p. This is then sent to B; while B computes g^b mod p, and transmits
-this to A, b being generated by B. Both a and b must be smaller than
-p-1.
-
-These private keys are generated upon startup, and they are not changed
-while the connection exists. A possible feature in the future is to
-dynamically change the keys, every hour for example.
-
-Both parties then calculate g^ab mod p = k. k is the new, shared, but
-still secret key.
-
-To obtain a key k of a sufficient length (128 bits in our vpnd), p
-should be 2^129-1 or more.
-
-
-@c ==================================================================
-@node Authentication, Protection, Key Management, Security
-@subsection Authentication
-@c FIXME: recheck
-
-@cindex man-in-the-middle attack
-Because the Diffie-Hellman protocol is in itself vulnerable to the
-``man-in-the-middle attack,'' we should introduce an authentication
-system.
-
-We will let A transmit a passphrase that is also known to B encrypted
-with g^a, before A sends this to B. This way, B can check whether A is
-really A or just someone else.
-
-@cindex passphrase
-This passphrase should be 2304 bits for a symmetric encryption
-system. But since an asymmetric system is more secure, we could do with
-2048 bits. This only holds if the passphrase is very random.
-
-These passphrases could be stored in a file that is non-readable by
-anyone else but root; e.g. @file{/etc/vpn/passphrases}.
-
-The only thing that needs to be taken care of is how A announces its
-passphrase to B.
-
-
-@c ==================================================================
-@node Protection, , Authentication, Security
-@subsection Protecting your data
-
-Now we have securely hidden our data. But a malicious cracker may still
-bother you by randomly altering the encrypted data he intercepts.
-
-
-@c ==================================================================
-@node The Protocol, , Security, Technical information
-@section Detailed protocol specifications
-
-
-
-@menu
-* Data protocol::
-* Meta protocol::
+* Key Types::
@end menu
@c ==================================================================
-@node Data protocol, Meta protocol, The Protocol, The Protocol
-@subsection The data protocol
-
-The data that is sent through the UDP connection is formatted as follows:
-
-@example
-
- bytes | Contents
-----------------------
- 0-1 | The length of this packet, including all leading fields
- 2-5 | The destination IP address
- 6-... | The encrypted data
-
-@end example
-
-The method that was used to encrypt the data should be made known via
-the meta-protocol, during early identification stages.
-
-
-@c ==================================================================
-@node Meta protocol, , Data protocol, The Protocol
-@subsection The Meta protocol
-
-This protocol consists of separate packets of information, that are
-generally formatted thusly:
-
-@example
-
- bytes | Contents
-----------------------
- 0 | The request ID
- 1-... | (Optional: arguments)
-
-@end example
-
-What follows is a listing of possible request IDs.
-
-@table @samp
-@item ACK
-Acknowledge. This generally means that the authentication has been
-accepted by the remote computer. Takes no arguments.
-
-@example
-
- bytes | Contents
-----------------------
- 0 | `1'
-
-@end example
-
-@item AUTH_S_INIT
-@itemx AUTH_C_INIT
-Obsolete. Use @samp{BASIC_INFO}.
-
-@item AUTH_S_SPP
-@itemx AUTH_C_SPP
-Obsolete. Use @samp{PASSPHRASE}.
-
-@item AUTH_S_SKEY
-@itemx AUTH_C_SKEY
-Obsolete. Use @samp{PUBLIC_KEY}, @samp{REQ_KEY} and @samp{ANS_KEY}.
-
-@item AUTH_S_SACK
-@itemx AUTH_C_RACK
-Obsolete. Use @samp{ACK}.
-
-@item TERMREQ
-A request to terminate this connection, for whatever reason.
-
-@example
-
- bytes | Contents
-----------------------
- 0 | `30'
- 1-4 | The VPN IP address of the host that has exited
-
-@end example
-
-
-@item PINGTIMEOUT
-Terminate connection, but the reason must be a ping timeout.
-
-@example
-
- bytes | Contents
-----------------------
- 0 | `31'
- 1-4 | The VPN IP address of the host that has exited
-
-@end example
-
-
-@item PING
-Send probe to the other end, if he hasn't returned a @samp{PONG} within
-10 seconds, the connection is considered to be dead and will be
-terminated, we should try to notify the other by sending a
-@samp{PINGTIMEOUT} packet.
-
-@example
-
- bytes | Contents
-----------------------
- 0 | `40'
-
-@end example
-
-
-@item PONG
-See explanation for @samp{PING}
-
-@example
-
- bytes | Contents
-----------------------
- 0 | `41'
-
-@end example
-
-
-@item ADD_HOST
-Send an @samp{ADD_HOST} packet if you want to propagate all your current
-connections to a new computer on a network. If we get this request, we
-must forward it to everyone that hasn't got it yet.
-
-@example
-
- bytes | Contents
-----------------------
- 0 | `60'
- 1-4 | The real IP address of the new host
- 5-8 | The VPN IP address of the new host
- 9-12 | The VPN netmask
- 13-14 | The port number that the new host listens on
-
-@end example
-
+@node Key Types, , Security, Security
+@subsection Key Types
+@c FIXME: check if I'm not talking nonsense
-@item BASIC_INFO
-This packet will contain all necessary basic information about
-ourselves, such as the port we listen on and our desired VPN IP address.
+There are several types of encryption keys. Tinc uses two of them,
+symmetric private keypairs and public/private keypairs.
-@example
-
- bytes | Contents
-----------------------
- 0 | `61'
- 1 | The protocol version.
- | This chapter describes version 4.
- 2-3 | The port number that the new host listens on
- 4-7 | The VPN IP address of the new host
- 8-11 | The VPN netmask
-
-@end example
-
-
-@item PASSPHRASE
-Send an encrypted passphrase. Should be encrypted with our
-@strong{public} key, and it must reach us before a @samp{PUBLIC_KEY}
-request.
-
-@example
-
- bytes | Contents
-----------------------
- 0 | `62'
- 1-2 | The length of the encrypted passphrase
- 3-... | The encrypted passphrase
-
-@end example
+Public/private keypairs are used in public key cryptography. It enables
+someone to send out a public key with which other people can encrypt their
+data. The encrypted data now can only be decrypted by the person who has
+the private key that matches the public key. So, a public key only allows
+@emph{other} people to send encrypted messages to you. This is very useful
+in setting up private communications channels. Just send out your public key
+and other people can talk to you in a secure way. But how can you know
+the other person is who she says she is? This is done by sending out an
+encrypted challenge that only the person with the right private key can decode
+an respond to.
+However, encryption with public/private keys is very slow. Symmetric key cryptography
+is orders of magnitudes faster, but it is very hard to safely exchange the symmetric
+keys, since they should be kept private.
-@item PUBLIC_KEY
-This is only used during authentication of a new connection, later on we
-may use @samp{REQ_KEY} and @samp{ANS_KEY}.
-
-@example
-
- bytes | Contents
-----------------------
- 0 | `63'
- 1-2 | The length of the key
- 3-... | The public key, given in base-36
-
-@end example
-
-
-@item HOLD
-@itemx RESUME
-Unused.
-
-@item CALCULATE
-@itemx CALC_RES
-@itemx ALMOST_KEY
-Never been in use.
-
-@item REQ_KEY
-Request a public key from someone and return it to the sender of this
-request using a @samp{ANS_KEY} packet. If we get such request, we must
-forward it to the connection that leads to the destination.
-
-@example
-
- bytes | Contents
-----------------------
- 0 | `160'
- 1-4 | The source VPN IP address
- 5-8 | The destination VPN IP address
- 9-14 | `0'
-
-@end example
-
-
-@item ANS_KEY
-Answer to a @samp{REQ_KEY} request, forward it to the destination if it
-is not meant for us.
-
-@example
-
- bytes | Contents
-----------------------
- 0 | `161'
- 1-4 | The source VPN IP address
- 5-8 | The destination VPN IP address
- 9-12 | The expiration date/time in seconds
- 13-14 | The key length
- 15-... | The public key in base-36
-
-@end example
-
-
-@item KEY_CHANGED
-The source computer wants to tell that it has regenerated its private
-and public keys, so anything going there must be encrypted with a new
-shared key.
-
-@example
-
- bytes | Contents
-----------------------
- 0 | `162'
- 1-4 | The source VPN IP address
-
-@end example
-
-
-@end table
+The idea is to use public/private cryptography for authentication, and for
+exchanging symmetric keys in a safe way. After that, all communications are encrypted
+with the symmetric cipher.
@c ==================================================================
tinc's main page is at @url{http://tinc.nl.linux.org/},
this server is located in the Netherlands.
-We have an IRC channel on the Open Projects IRC network. Connect to
+We have an IRC channel on the Open Projects IRC network. Connect to
@uref{http://openprojects.nu/services/irc.html, irc.openprojects.net},
and join channel #tinc.
@item Ivo Timmermans (zarq) (@email{itimmermans@@bigfoot.com})
Main coder/hacker and maintainer of the package.
-@item Guus Sliepen (guus)
+@item Guus Sliepen (guus) (@email{guus@@sliepen.warande.net})
Originator of it all, co-author.
-@item Wessel Dankers (Ubiq)
-General obfuscater of the code.
+@item Wessel Dankers (Ubiq) (@email{wsl@@nl.linux.org})
+For the name `tinc' and various suggestions.
@end table
-Thank you's to: Dekan, Emphyrio, vDong
-
-Greetings to: braque, Fluor, giggles, macro, smoke, tribbel
+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 @file{THANKS} in
+the source distribution.
@c ==================================================================
projects / tinc / blobdiff