1 \input texinfo @c -*-texinfo-*-
8 @include tincinclude.texi
11 @dircategory Networking tools
13 * tinc: (tinc). The tinc Manual.
16 This is the info manual for @value{PACKAGE} version @value{VERSION}, a Virtual Private Network daemon.
18 Copyright @copyright{} 1998-2016 Ivo Timmermans,
19 Guus Sliepen <guus@@tinc-vpn.org> and
20 Wessel Dankers <wsl@@tinc-vpn.org>.
22 Permission is granted to make and distribute verbatim copies of this
23 manual provided the copyright notice and this permission notice are
24 preserved on all copies.
26 Permission is granted to copy and distribute modified versions of this
27 manual under the conditions for verbatim copying, provided that the
28 entire resulting derived work is distributed under the terms of a
29 permission notice identical to this one.
39 @subtitle Setting up a Virtual Private Network with tinc
40 @author Ivo Timmermans and Guus Sliepen
43 @vskip 0pt plus 1filll
44 This is the info manual for @value{PACKAGE} version @value{VERSION}, a Virtual Private Network daemon.
46 Copyright @copyright{} 1998-2016 Ivo Timmermans,
47 Guus Sliepen <guus@@tinc-vpn.org> and
48 Wessel Dankers <wsl@@tinc-vpn.org>.
50 Permission is granted to make and distribute verbatim copies of this
51 manual provided the copyright notice and this permission notice are
52 preserved on all copies.
54 Permission is granted to copy and distribute modified versions of this
55 manual under the conditions for verbatim copying, provided that the
56 entire resulting derived work is distributed under the terms of a
57 permission notice identical to this one.
62 @c ==================================================================
74 * Technical information::
75 * Platform specific information::
77 * Concept Index:: All used terms explained
81 @c ==================================================================
86 Tinc is a Virtual Private Network (VPN) daemon that uses tunneling and
87 encryption to create a secure private network between hosts on the
90 Because the tunnel appears to the IP level network code as a normal
91 network device, there is no need to adapt any existing software.
92 The encrypted tunnels allows VPN sites to share information with each other
93 over the Internet without exposing any information to others.
95 This document is the manual for tinc. Included are chapters on how to
96 configure your computer to use tinc, as well as the configuration
97 process of tinc itself.
100 * Virtual Private Networks::
102 * Supported platforms::
105 @c ==================================================================
106 @node Virtual Private Networks
107 @section Virtual Private Networks
110 A Virtual Private Network or VPN is a network that can only be accessed
111 by a few elected computers that participate. This goal is achievable in
112 more than just one way.
115 Private networks can consist of a single stand-alone Ethernet LAN. Or
116 even two computers hooked up using a null-modem cable. In these cases,
118 obvious that the network is @emph{private}, no one can access it from the
119 outside. But if your computers are linked to the Internet, the network
120 is not private anymore, unless one uses firewalls to block all private
121 traffic. But then, there is no way to send private data to trusted
122 computers on the other end of the Internet.
125 This problem can be solved by using @emph{virtual} networks. Virtual
126 networks can live on top of other networks, but they use encapsulation to
127 keep using their private address space so they do not interfere with
128 the Internet. Mostly, virtual networks appear like a single LAN, even though
129 they can span the entire world. But virtual networks can't be secured
130 by using firewalls, because the traffic that flows through it has to go
131 through the Internet, where other people can look at it.
133 As is the case with either type of VPN, anybody could eavesdrop. Or
134 worse, alter data. Hence it's probably advisable to encrypt the data
135 that flows over the network.
137 When one introduces encryption, we can form a true VPN. Other people may
138 see encrypted traffic, but if they don't know how to decipher it (they
139 need to know the key for that), they cannot read the information that flows
140 through the VPN. This is what tinc was made for.
143 @c ==================================================================
148 I really don't quite remember what got us started, but it must have been
149 Guus' idea. He wrote a simple implementation (about 50 lines of C) that
150 used the ethertap device that Linux knows of since somewhere
151 about kernel 2.1.60. It didn't work immediately and he improved it a
152 bit. At this stage, the project was still simply called "vpnd".
154 Since then, a lot has changed---to say the least.
157 Tinc now supports encryption, it consists of a single daemon (tincd) for
158 both the receiving and sending end, it has become largely
159 runtime-configurable---in short, it has become a full-fledged
160 professional package.
162 @cindex traditional VPNs
164 Tinc also allows more than two sites to connect to eachother and form a single VPN.
165 Traditionally VPNs are created by making tunnels, which only have two endpoints.
166 Larger VPNs with more sites are created by adding more tunnels.
167 Tinc takes another approach: only endpoints are specified,
168 the software itself will take care of creating the tunnels.
169 This allows for easier configuration and improved scalability.
171 A lot can---and will be---changed. We have a number of things that we would like to
172 see in the future releases of tinc. Not everything will be available in
173 the near future. Our first objective is to make tinc work perfectly as
174 it stands, and then add more advanced features.
176 Meanwhile, we're always open-minded towards new ideas. And we're
180 @c ==================================================================
181 @node Supported platforms
182 @section Supported platforms
185 Tinc has been verified to work under Linux, FreeBSD, OpenBSD, NetBSD, MacOS/X (Darwin), Solaris, and Windows (both natively and in a Cygwin environment),
186 with various hardware architectures. These are some of the platforms
187 that are supported by the universal tun/tap device driver or other virtual network device drivers.
188 Without such a driver, tinc will most
189 likely compile and run, but it will not be able to send or receive data
193 For an up to date list of supported platforms, please check the list on
195 @uref{https://www.tinc-vpn.org/platforms/}.
203 @c Preparing your system
210 @c ==================================================================
212 @chapter Preparations
214 This chapter contains information on how to prepare your system to
218 * Configuring the kernel::
223 @c ==================================================================
224 @node Configuring the kernel
225 @section Configuring the kernel
228 * Configuration of Linux kernels::
229 * Configuration of FreeBSD kernels::
230 * Configuration of OpenBSD kernels::
231 * Configuration of NetBSD kernels::
232 * Configuration of Solaris kernels::
233 * Configuration of Darwin (MacOS/X) kernels::
234 * Configuration of Windows::
238 @c ==================================================================
239 @node Configuration of Linux kernels
240 @subsection Configuration of Linux kernels
242 @cindex Universal tun/tap
243 For tinc to work, you need a kernel that supports the Universal tun/tap device.
244 Most distributions come with kernels that already support this.
245 Here are the options you have to turn on when configuring a new kernel:
248 Code maturity level options
249 [*] Prompt for development and/or incomplete code/drivers
250 Network device support
251 <M> Universal tun/tap device driver support
254 It's not necessary to compile this driver as a module, even if you are going to
255 run more than one instance of tinc.
257 If you decide to build the tun/tap driver as a kernel module, add these lines
258 to @file{/etc/modules.conf}:
261 alias char-major-10-200 tun
265 @c ==================================================================
266 @node Configuration of FreeBSD kernels
267 @subsection Configuration of FreeBSD kernels
269 For FreeBSD version 4.1 and higher, tun and tap drivers are included in the default kernel configuration.
270 The tap driver can be loaded with @code{kldload if_tap}, or by adding @code{if_tap_load="YES"} to @file{/boot/loader.conf}.
273 @c ==================================================================
274 @node Configuration of OpenBSD kernels
275 @subsection Configuration of OpenBSD kernels
277 Recent versions of OpenBSD come with both tun and tap devices enabled in the default kernel configuration.
280 @c ==================================================================
281 @node Configuration of NetBSD kernels
282 @subsection Configuration of NetBSD kernels
284 For NetBSD version 1.5.2 and higher,
285 the tun driver is included in the default kernel configuration.
287 Tunneling IPv6 may not work on NetBSD's tun device.
290 @c ==================================================================
291 @node Configuration of Solaris kernels
292 @subsection Configuration of Solaris kernels
294 For Solaris 8 (SunOS 5.8) and higher,
295 the tun driver may or may not be included in the default kernel configuration.
296 If it isn't, the source can be downloaded from @uref{http://vtun.sourceforge.net/tun/}.
297 For x86 and sparc64 architectures, precompiled versions can be found at @uref{https://www.monkey.org/~dugsong/fragroute/}.
298 If the @file{net/if_tun.h} header file is missing, install it from the source package.
301 @c ==================================================================
302 @node Configuration of Darwin (MacOS/X) kernels
303 @subsection Configuration of Darwin (MacOS/X) kernels
305 Tinc on Darwin relies on a tunnel driver for its data acquisition from the kernel.
306 OS X version 10.6.8 and later have a built-in tun driver called "utun".
307 Tinc also supports the driver from @uref{http://tuntaposx.sourceforge.net/},
308 which supports both tun and tap style devices,
310 By default, tinc expects the tuntaposx driver to be installed.
311 To use the utun driver, set add @code{Device = utunX} to @file{tinc.conf},
312 where X is the desired number for the utun interface.
313 You can also omit the number, in which case the first free number will be chosen.
316 @c ==================================================================
317 @node Configuration of Windows
318 @subsection Configuration of Windows
320 You will need to install the latest TAP-Win32 driver from OpenVPN.
321 You can download it from @uref{https://openvpn.net/index.php/open-source/downloads.html}.
322 Using the Network Connections control panel,
323 configure the TAP-Win32 network interface in the same way as you would do from the tinc-up script,
324 as explained in the rest of the documentation.
327 @c ==================================================================
333 Before you can configure or build tinc, you need to have the LibreSSL or OpenSSL, zlib,
334 lzo, curses and readline libraries installed on your system. If you try to
335 configure tinc without having them installed, configure will give you an error
347 @c ==================================================================
348 @node LibreSSL/OpenSSL
349 @subsection LibreSSL/OpenSSL
353 For all cryptography-related functions, tinc uses the functions provided
354 by the LibreSSL or the OpenSSL library.
356 If this library is not installed, you wil get an error when configuring
357 tinc for build. Support for running tinc with other cryptographic libraries
358 installed @emph{may} be added in the future.
360 You can use your operating system's package manager to install this if
361 available. Make sure you install the development AND runtime versions
364 If your operating system comes neither with LibreSSL or OpenSSL, you have to
365 install one manually. It is recommended that you get the latest version of
366 LibreSSL from @url{http://www.libressl.org/}. Instructions on how to
367 configure, build and install this package are included within the package.
368 Please make sure you build development and runtime libraries (which is the
371 If you installed the LibreSSL or OpenSSL libraries from source, it may be necessary
372 to let configure know where they are, by passing configure one of the
373 --with-openssl-* parameters. Note that you even have to use --with-openssl-* if you
377 --with-openssl=DIR LibreSSL/OpenSSL library and headers prefix
378 --with-openssl-include=DIR LibreSSL/OpenSSL headers directory
379 (Default is OPENSSL_DIR/include)
380 --with-openssl-lib=DIR LibreSSL/OpenSSL library directory
381 (Default is OPENSSL_DIR/lib)
385 @subsubheading License
388 The complete source code of tinc is covered by the GNU GPL version 2.
389 Since the license under which OpenSSL is distributed is not directly
390 compatible with the terms of the GNU GPL
391 @uref{https://www.openssl.org/support/faq.html#LEGAL2}, we
392 include an exemption to the GPL (see also the file COPYING.README) to allow
393 everyone to create a statically or dynamically linked executable:
396 This program is released under the GPL with the additional exemption
397 that compiling, linking, and/or using OpenSSL is allowed. You may
398 provide binary packages linked to the OpenSSL libraries, provided that
399 all other requirements of the GPL are met.
402 Since the LZO library used by tinc is also covered by the GPL,
403 we also present the following exemption:
406 Hereby I grant a special exception to the tinc VPN project
407 (https://www.tinc-vpn.org/) to link the LZO library with the OpenSSL library
408 (https://www.openssl.org).
410 Markus F.X.J. Oberhumer
414 @c ==================================================================
419 For the optional compression of UDP packets, tinc uses the functions provided
422 If this library is not installed, you wil get an error when running the
423 configure script. You can either install the zlib library, or disable support
424 for zlib compression by using the "--disable-zlib" option when running the
425 configure script. Note that if you disable support for zlib, the resulting
426 binary will not work correctly on VPNs where zlib compression is used.
428 You can use your operating system's package manager to install this if
429 available. Make sure you install the development AND runtime versions
432 If you have to install zlib manually, you can get the source code
433 from @url{http://www.zlib.net/}. Instructions on how to configure,
434 build and install this package are included within the package. Please
435 make sure you build development and runtime libraries (which is the
439 @c ==================================================================
444 Another form of compression is offered using the LZO library.
446 If this library is not installed, you wil get an error when running the
447 configure script. You can either install the LZO library, or disable support
448 for LZO compression by using the "--disable-lzo" option when running the
449 configure script. Note that if you disable support for LZO, the resulting
450 binary will not work correctly on VPNs where LZO compression is used.
452 You can use your operating system's package manager to install this if
453 available. Make sure you install the development AND runtime versions
456 If you have to install lzo manually, you can get the source code
457 from @url{https://www.oberhumer.com/opensource/lzo/}. Instructions on how to configure,
458 build and install this package are included within the package. Please
459 make sure you build development and runtime libraries (which is the
463 @c ==================================================================
465 @subsection libcurses
468 For the "tinc top" command, tinc requires a curses library.
470 If this library is not installed, you wil get an error when running the
471 configure script. You can either install a suitable curses library, or disable
472 all functionality that depends on a curses library by using the
473 "--disable-curses" option when running the configure script.
475 There are several curses libraries. It is recommended that you install
476 "ncurses" (@url{http://invisible-island.net/ncurses/}),
477 however other curses libraries should also work.
478 In particular, "PDCurses" (@url{http://pdcurses.sourceforge.net/})
479 is recommended if you want to compile tinc for Windows.
481 You can use your operating system's package manager to install this if
482 available. Make sure you install the development AND runtime versions
486 @c ==================================================================
488 @subsection libreadline
491 For the "tinc" command's shell functionality, tinc uses the readline library.
493 If this library is not installed, you wil get an error when running the
494 configure script. You can either install a suitable readline library, or
495 disable all functionality that depends on a readline library by using the
496 "--disable-readline" option when running the configure script.
498 You can use your operating system's package manager to install this if
499 available. Make sure you install the development AND runtime versions
502 If you have to install libreadline manually, you can get the source code from
503 @url{http://www.gnu.org/software/readline/}. Instructions on how to configure,
504 build and install this package are included within the package. Please make
505 sure you build development and runtime libraries (which is the default).
517 @c ==================================================================
519 @chapter Installation
521 If you use Debian, you may want to install one of the
522 precompiled packages for your system. These packages are equipped with
523 system startup scripts and sample configurations.
525 If you cannot use one of the precompiled packages, or you want to compile tinc
526 for yourself, you can use the source. The source is distributed under
527 the GNU General Public License (GPL). Download the source from the
528 @uref{https://www.tinc-vpn.org/download/, download page}.
530 Tinc comes in a convenient autoconf/automake package, which you can just
531 treat the same as any other package. Which is just untar it, type
532 `./configure' and then `make'.
533 More detailed instructions are in the file @file{INSTALL}, which is
534 included in the source distribution.
537 * Building and installing tinc::
542 @c ==================================================================
543 @node Building and installing tinc
544 @section Building and installing tinc
546 Detailed instructions on configuring the source, building tinc and installing tinc
547 can be found in the file called @file{INSTALL}.
549 @cindex binary package
550 If you happen to have a binary package for tinc for your distribution,
551 you can use the package management tools of that distribution to install tinc.
552 The documentation that comes along with your distribution will tell you how to do that.
555 * Darwin (MacOS/X) build environment::
556 * Cygwin (Windows) build environment::
557 * MinGW (Windows) build environment::
561 @c ==================================================================
562 @node Darwin (MacOS/X) build environment
563 @subsection Darwin (MacOS/X) build environment
565 In order to build tinc on Darwin, you need to install Xcode from @uref{https://developer.apple.com/xcode/}.
566 It might also help to install a recent version of Fink from @uref{http://www.finkproject.org/}.
568 You need to download and install LibreSSL (or OpenSSL) and LZO,
569 either directly from their websites (see @ref{Libraries}) or using Fink.
571 @c ==================================================================
572 @node Cygwin (Windows) build environment
573 @subsection Cygwin (Windows) build environment
575 If Cygwin hasn't already been installed, install it directly from
576 @uref{https://www.cygwin.com/}.
578 When tinc is compiled in a Cygwin environment, it can only be run in this environment,
579 but all programs, including those started outside the Cygwin environment, will be able to use the VPN.
580 It will also support all features.
582 @c ==================================================================
583 @node MinGW (Windows) build environment
584 @subsection MinGW (Windows) build environment
586 You will need to install the MinGW environment from @uref{http://www.mingw.org}.
587 You also need to download and install LibreSSL (or OpenSSL) and LZO.
589 When tinc is compiled using MinGW it runs natively under Windows,
590 it is not necessary to keep MinGW installed.
592 When detaching, tinc will install itself as a service,
593 which will be restarted automatically after reboots.
596 @c ==================================================================
598 @section System files
600 Before you can run tinc, you must make sure you have all the needed
601 files on your system.
609 @c ==================================================================
611 @subsection Device files
614 Most operating systems nowadays come with the necessary device files by default,
615 or they have a mechanism to create them on demand.
617 If you use Linux and do not have udev installed,
618 you may need to create the following device file if it does not exist:
621 mknod -m 600 /dev/net/tun c 10 200
625 @c ==================================================================
627 @subsection Other files
629 @subsubheading @file{/etc/networks}
631 You may add a line to @file{/etc/networks} so that your VPN will get a
632 symbolic name. For example:
638 @subsubheading @file{/etc/services}
641 You may add this line to @file{/etc/services}. The effect is that you
642 may supply a @samp{tinc} as a valid port number to some programs. The
643 number 655 is registered with the IANA.
648 # Ivo Timmermans <ivo@@tinc-vpn.org>
663 @c ==================================================================
665 @chapter Configuration
668 * Configuration introduction::
669 * Multiple networks::
670 * How connections work::
671 * Configuration files::
672 * Network interfaces::
673 * Example configuration::
676 @c ==================================================================
677 @node Configuration introduction
678 @section Configuration introduction
680 Before actually starting to configure tinc and editing files,
681 make sure you have read this entire section so you know what to expect.
682 Then, make it clear to yourself how you want to organize your VPN:
683 What are the nodes (computers running tinc)?
684 What IP addresses/subnets do they have?
685 What is the network mask of the entire VPN?
686 Do you need special firewall rules?
687 Do you have to set up masquerading or forwarding rules?
688 Do you want to run tinc in router mode or switch mode?
689 These questions can only be answered by yourself,
690 you will not find the answers in this documentation.
691 Make sure you have an adequate understanding of networks in general.
692 @cindex Network Administrators Guide
693 A good resource on networking is the
694 @uref{http://www.tldp.org/LDP/nag2/, Linux Network Administrators Guide}.
696 If you have everything clearly pictured in your mind,
697 proceed in the following order:
698 First, create the initial configuration files and public/private keypairs using the following command:
700 tinc -n @var{NETNAME} init @var{NAME}
702 Second, use @samp{tinc -n @var{NETNAME} add ...} to further configure tinc.
703 Finally, export your host configuration file using @samp{tinc -n @var{NETNAME} export} and send it to those
704 people or computers you want tinc to connect to.
705 They should send you their host configuration file back, which you can import using @samp{tinc -n @var{NETNAME} import}.
707 These steps are described in the subsections below.
710 @c ==================================================================
711 @node Multiple networks
712 @section Multiple networks
714 @cindex multiple networks
717 In order to allow you to run more than one tinc daemon on one computer,
718 for instance if your computer is part of more than one VPN,
719 you can assign a @var{netname} to your VPN.
720 It is not required if you only run one tinc daemon,
721 it doesn't even have to be the same on all the nodes of your VPN,
722 but it is recommended that you choose one anyway.
724 We will asume you use a netname throughout this document.
725 This means that you call tinc with the -n argument,
726 which will specify the netname.
728 The effect of this option is that tinc will set its configuration
729 root to @file{@value{sysconfdir}/tinc/@var{netname}/}, where @var{netname} is your argument to the -n option.
730 You will also notice that log messages it appears in syslog as coming from @file{tinc.@var{netname}},
731 and on Linux, unless specified otherwise, the name of the virtual network interface will be the same as the network name.
733 However, it is not strictly necessary that you call tinc with the -n
734 option. If you do not use it, the network name will just be empty, and
735 tinc will look for files in @file{@value{sysconfdir}/tinc/} instead of
736 @file{@value{sysconfdir}/tinc/@var{netname}/};
737 the configuration file will then be @file{@value{sysconfdir}/tinc/tinc.conf},
738 and the host configuration files are expected to be in @file{@value{sysconfdir}/tinc/hosts/}.
741 @c ==================================================================
742 @node How connections work
743 @section How connections work
745 When tinc starts up, it parses the command-line options and then
746 reads in the configuration file tinc.conf.
747 If it sees one or more `ConnectTo' values pointing to other tinc daemons in that file,
748 it will try to connect to those other daemons.
749 Whether this succeeds or not and whether `ConnectTo' is specified or not,
750 tinc will listen for incoming connection from other deamons.
751 If you did specify a `ConnectTo' value and the other side is not responding,
752 tinc will keep retrying.
753 This means that once started, tinc will stay running until you tell it to stop,
754 and failures to connect to other tinc daemons will not stop your tinc daemon
755 for trying again later.
756 This means you don't have to intervene if there are temporary network problems.
760 There is no real distinction between a server and a client in tinc.
761 If you wish, you can view a tinc daemon without a `ConnectTo' value as a server,
762 and one which does specify such a value as a client.
763 It does not matter if two tinc daemons have a `ConnectTo' value pointing to each other however.
765 Connections specified using `ConnectTo' are so-called meta-connections.
766 Tinc daemons exchange information about all other daemon they know about via these meta-connections.
767 After learning about all the daemons in the VPN,
768 tinc will create other connections as necessary in order to communicate with them.
769 For example, if there are three daemons named A, B and C, and A has @samp{ConnectTo = B} in its tinc.conf file,
770 and C has @samp{ConnectTo = B} in its tinc.conf file, then A will learn about C from B,
771 and will be able to exchange VPN packets with C without the need to have @samp{ConnectTo = C} in its tinc.conf file.
773 It could be that some daemons are located behind a Network Address Translation (NAT) device, or behind a firewall.
774 In the above scenario with three daemons, if A and C are behind a NAT,
775 B will automatically help A and C punch holes through their NAT,
776 in a way similar to the STUN protocol, so that A and C can still communicate with each other directly.
777 It is not always possible to do this however, and firewalls might also prevent direct communication.
778 In that case, VPN packets between A and C will be forwarded by B.
780 In effect, all nodes in the VPN will be able to talk to each other, as long as
781 their is a path of meta-connections between them, and whenever possible, two
782 nodes will communicate with each other directly.
785 @c ==================================================================
786 @node Configuration files
787 @section Configuration files
789 The actual configuration of the daemon is done in the file
790 @file{@value{sysconfdir}/tinc/@var{netname}/tinc.conf} and at least one other file in the directory
791 @file{@value{sysconfdir}/tinc/@var{netname}/hosts/}.
793 An optionnal directory @file{@value{sysconfdir}/tinc/@var{netname}/conf.d} can be added from which
794 any .conf file will be read.
796 These file consists of comments (lines started with a #) or assignments
803 The variable names are case insensitive, and any spaces, tabs, newlines
804 and carriage returns are ignored. Note: it is not required that you put
805 in the `=' sign, but doing so improves readability. If you leave it
806 out, remember to replace it with at least one space character.
808 The server configuration is complemented with host specific configuration (see
809 the next section). Although all host configuration options for the local node
810 listed in this document can also be put in
811 @file{@value{sysconfdir}/tinc/@var{netname}/tinc.conf}, it is recommended to
812 put host specific configuration options in the host configuration file, as this
813 makes it easy to exchange with other nodes.
815 You can edit the config file manually, but it is recommended that you use
816 the tinc command to change configuration variables for you.
818 In the following two subsections all valid variables are listed in alphabetical order.
819 The default value is given between parentheses,
820 other comments are between square brackets.
823 * Main configuration variables::
824 * Host configuration variables::
830 @c ==================================================================
831 @node Main configuration variables
832 @subsection Main configuration variables
835 @cindex AddressFamily
836 @item AddressFamily = <ipv4|ipv6|any> (any)
837 This option affects the address family of listening and outgoing sockets.
838 If any is selected, then depending on the operating system
839 both IPv4 and IPv6 or just IPv6 listening sockets will be created.
842 @item AutoConnect = <yes|no> (no) [experimental]
843 If set to yes, tinc will automatically set up meta connections to other nodes,
844 without requiring @var{ConnectTo} variables.
846 @cindex BindToAddress
847 @item BindToAddress = <@var{address}> [<@var{port}>]
848 This is the same as ListenAddress, however the address given with the BindToAddress option
849 will also be used for outgoing connections.
850 This is useful if your computer has more than one IPv4 or IPv6 address,
851 and you want tinc to only use a specific one for outgoing packets.
853 @cindex BindToInterface
854 @item BindToInterface = <@var{interface}> [experimental]
855 If you have more than one network interface in your computer, tinc will
856 by default listen on all of them for incoming connections. It is
857 possible to bind tinc to a single interface like eth0 or ppp0 with this
860 This option may not work on all platforms.
861 Also, on some platforms it will not actually bind to an interface,
862 but rather to the address that the interface has at the moment a socket is created.
865 @item Broadcast = <no | mst | direct> (mst) [experimental]
866 This option selects the way broadcast packets are sent to other daemons.
867 @emph{NOTE: all nodes in a VPN must use the same Broadcast mode, otherwise routing loops can form.}
871 Broadcast packets are never sent to other nodes.
874 Broadcast packets are sent and forwarded via the VPN's Minimum Spanning Tree.
875 This ensures broadcast packets reach all nodes.
878 Broadcast packets are sent directly to all nodes that can be reached directly.
879 Broadcast packets received from other nodes are never forwarded.
880 If the IndirectData option is also set, broadcast packets will only be sent to nodes which we have a meta connection to.
883 @cindex BroadcastSubnet
884 @item BroadcastSubnet = @var{address}[/@var{prefixlength}]
885 Declares a broadcast subnet.
886 Any packet with a destination address falling into such a subnet will be routed as a broadcast
887 (provided all nodes have it declared).
888 This is most useful to declare subnet broadcast addresses (e.g. 10.42.255.255),
889 otherwise tinc won't know what to do with them.
891 Note that global broadcast addresses (MAC ff:ff:ff:ff:ff:ff, IPv4 255.255.255.255),
892 as well as multicast space (IPv4 224.0.0.0/4, IPv6 ff00::/8)
893 are always considered broadcast addresses and don't need to be declared.
896 @item ConnectTo = <@var{name}>
897 Specifies which other tinc daemon to connect to on startup.
898 Multiple ConnectTo variables may be specified,
899 in which case outgoing connections to each specified tinc daemon are made.
900 The names should be known to this tinc daemon
901 (i.e., there should be a host configuration file for the name on the ConnectTo line).
903 If you don't specify a host with ConnectTo and don't enable AutoConnect,
904 tinc won't try to connect to other daemons at all,
905 and will instead just listen for incoming connections.
908 @item DecrementTTL = <yes | no> (no) [experimental]
909 When enabled, tinc will decrement the Time To Live field in IPv4 packets, or the Hop Limit field in IPv6 packets,
910 before forwarding a received packet to the virtual network device or to another node,
911 and will drop packets that have a TTL value of zero,
912 in which case it will send an ICMP Time Exceeded packet back.
914 Do not use this option if you use switch mode and want to use IPv6.
917 @item Device = <@var{device}> (@file{/dev/tap0}, @file{/dev/net/tun} or other depending on platform)
918 The virtual network device to use.
919 Tinc will automatically detect what kind of device it is.
920 Note that you can only use one device per daemon.
921 Under Windows, use @var{Interface} instead of @var{Device}.
922 Note that you can only use one device per daemon.
923 See also @ref{Device files}.
925 @cindex DeviceStandby
926 @item DeviceStandby = <yes | no> (no)
927 When disabled, tinc calls @file{tinc-up} on startup, and @file{tinc-down} on shutdown.
928 When enabled, tinc will only call @file{tinc-up} when at least one node is reachable,
929 and will call @file{tinc-down} as soon as no nodes are reachable.
930 On Windows, this also determines when the virtual network interface "cable" is "plugged".
933 @item DeviceType = <@var{type}> (platform dependent)
934 The type of the virtual network device.
935 Tinc will normally automatically select the right type of tun/tap interface, and this option should not be used.
936 However, this option can be used to select one of the special interface types, if support for them is compiled in.
941 Use a dummy interface.
942 No packets are ever read or written to a virtual network device.
943 Useful for testing, or when setting up a node that only forwards packets for other nodes.
947 Open a raw socket, and bind it to a pre-existing
948 @var{Interface} (eth0 by default).
949 All packets are read from this interface.
950 Packets received for the local node are written to the raw socket.
951 However, at least on Linux, the operating system does not process IP packets destined for the local host.
955 Open a multicast UDP socket and bind it to the address and port (separated by spaces) and optionally a TTL value specified using @var{Device}.
956 Packets are read from and written to this multicast socket.
957 This can be used to connect to UML, QEMU or KVM instances listening on the same multicast address.
958 Do NOT connect multiple tinc daemons to the same multicast address, this will very likely cause routing loops.
959 Also note that this can cause decrypted VPN packets to be sent out on a real network if misconfigured.
962 @item uml (not compiled in by default)
963 Create a UNIX socket with the filename specified by
964 @var{Device}, or @file{@value{localstatedir}/run/@var{netname}.umlsocket}
966 Tinc will wait for a User Mode Linux instance to connect to this socket.
969 @item vde (not compiled in by default)
970 Uses the libvdeplug library to connect to a Virtual Distributed Ethernet switch,
971 using the UNIX socket specified by
972 @var{Device}, or @file{@value{localstatedir}/run/vde.ctl}
976 Also, in case tinc does not seem to correctly interpret packets received from the virtual network device,
977 it can be used to change the way packets are interpreted:
980 @item tun (BSD and Linux)
982 Depending on the platform, this can either be with or without an address family header (see below).
985 @item tunnohead (BSD)
986 Set type to tun without an address family header.
987 Tinc will expect packets read from the virtual network device to start with an IP header.
988 On some platforms IPv6 packets cannot be read from or written to the device in this mode.
991 @item tunifhead (BSD)
992 Set type to tun with an address family header.
993 Tinc will expect packets read from the virtual network device
994 to start with a four byte header containing the address family,
995 followed by an IP header.
996 This mode should support both IPv4 and IPv6 packets.
1001 This is only supported on OS X version 10.6.8 and higher, but doesn't require the tuntaposx module.
1002 This mode should support both IPv4 and IPv6 packets.
1004 @item tap (BSD and Linux)
1006 Tinc will expect packets read from the virtual network device
1007 to start with an Ethernet header.
1011 @item DirectOnly = <yes|no> (no) [experimental]
1012 When this option is enabled, packets that cannot be sent directly to the destination node,
1013 but which would have to be forwarded by an intermediate node, are dropped instead.
1014 When combined with the IndirectData option,
1015 packets for nodes for which we do not have a meta connection with are also dropped.
1017 @cindex Ed25519PrivateKeyFile
1018 @item Ed25519PrivateKeyFile = <@var{path}> (@file{@value{sysconfdir}/tinc/@var{netname}/ed25519_key.priv})
1019 The file in which the private Ed25519 key of this tinc daemon resides.
1020 This is only used if ExperimentalProtocol is enabled.
1022 @cindex ExperimentalProtocol
1023 @item ExperimentalProtocol = <yes|no> (yes)
1024 When this option is enabled, the SPTPS protocol will be used when connecting to nodes that also support it.
1025 Ephemeral ECDH will be used for key exchanges,
1026 and Ed25519 will be used instead of RSA for authentication.
1027 When enabled, an Ed25519 key must have been generated before with
1028 @samp{tinc generate-ed25519-keys}.
1031 @item Forwarding = <off|internal|kernel> (internal) [experimental]
1032 This option selects the way indirect packets are forwarded.
1036 Incoming packets that are not meant for the local node,
1037 but which should be forwarded to another node, are dropped.
1040 Incoming packets that are meant for another node are forwarded by tinc internally.
1042 This is the default mode, and unless you really know you need another forwarding mode, don't change it.
1045 Incoming packets are always sent to the TUN/TAP device, even if the packets are not for the local node.
1046 This is less efficient, but allows the kernel to apply its routing and firewall rules on them,
1047 and can also help debugging.
1051 @item Hostnames = <yes|no> (no)
1052 This option selects whether IP addresses (both real and on the VPN)
1053 should be resolved. Since DNS lookups are blocking, it might affect
1054 tinc's efficiency, even stopping the daemon for a few seconds everytime
1055 it does a lookup if your DNS server is not responding.
1057 This does not affect resolving hostnames to IP addresses from the
1058 configuration file, but whether hostnames should be resolved while logging.
1061 @item Interface = <@var{interface}>
1062 Defines the name of the interface corresponding to the virtual network device.
1063 Depending on the operating system and the type of device this may or may not actually set the name of the interface.
1064 Under Windows, this variable is used to select which network interface will be used.
1065 If you specified a Device, this variable is almost always already correctly set.
1067 @cindex ListenAddress
1068 @item ListenAddress = <@var{address}> [<@var{port}>]
1069 If your computer has more than one IPv4 or IPv6 address, tinc
1070 will by default listen on all of them for incoming connections.
1071 This option can be used to restrict which addresses tinc listens on.
1072 Multiple ListenAddress variables may be specified,
1073 in which case listening sockets for each specified address are made.
1075 If no @var{port} is specified, the socket will listen on the port specified by the Port option,
1076 or to port 655 if neither is given.
1077 To only listen on a specific port but not to a specific address, use "*" for the @var{address}.
1079 @cindex LocalDiscovery
1080 @item LocalDiscovery = <yes | no> (no)
1081 When enabled, tinc will try to detect peers that are on the same local network.
1082 This will allow direct communication using LAN addresses, even if both peers are behind a NAT
1083 and they only ConnectTo a third node outside the NAT,
1084 which normally would prevent the peers from learning each other's LAN address.
1086 Currently, local discovery is implemented by sending some packets to the local address of the node during UDP discovery.
1087 This will not work with old nodes that don't transmit their local address.
1089 @cindex LocalDiscoveryAddress
1090 @item LocalDiscoveryAddress <@var{address}>
1091 If this variable is specified, local discovery packets are sent to the given @var{address}.
1094 @item Mode = <router|switch|hub> (router)
1095 This option selects the way packets are routed to other daemons.
1101 variables in the host configuration files will be used to form a routing table.
1102 Only packets of routable protocols (IPv4 and IPv6) are supported in this mode.
1104 This is the default mode, and unless you really know you need another mode, don't change it.
1108 In this mode the MAC addresses of the packets on the VPN will be used to
1109 dynamically create a routing table just like an Ethernet switch does.
1110 Unicast, multicast and broadcast packets of every protocol that runs over Ethernet are supported in this mode
1111 at the cost of frequent broadcast ARP requests and routing table updates.
1113 This mode is primarily useful if you want to bridge Ethernet segments.
1117 This mode is almost the same as the switch mode, but instead
1118 every packet will be broadcast to the other daemons
1119 while no routing table is managed.
1123 @item KeyExpire = <@var{seconds}> (3600)
1124 This option controls the time the encryption keys used to encrypt the data
1125 are valid. It is common practice to change keys at regular intervals to
1126 make it even harder for crackers, even though it is thought to be nearly
1127 impossible to crack a single key.
1130 @item MACExpire = <@var{seconds}> (600)
1131 This option controls the amount of time MAC addresses are kept before they are removed.
1132 This only has effect when Mode is set to "switch".
1134 @cindex MaxConnectionBurst
1135 @item MaxConnectionBurst = <@var{count}> (100)
1136 This option controls how many connections tinc accepts in quick succession.
1137 If there are more connections than the given number in a short time interval,
1138 tinc will reduce the number of accepted connections to only one per second,
1139 until the burst has passed.
1142 @item Name = <@var{name}> [required]
1143 This is a symbolic name for this connection.
1144 The name must consist only of alfanumeric and underscore characters (a-z, A-Z, 0-9 and _), and is case sensitive.
1146 If Name starts with a $, then the contents of the environment variable that follows will be used.
1147 In that case, invalid characters will be converted to underscores.
1148 If Name is $HOST, but no such environment variable exist,
1149 the hostname will be read using the gethostname() system call.
1151 @cindex PingInterval
1152 @item PingInterval = <@var{seconds}> (60)
1153 The number of seconds of inactivity that tinc will wait before sending a
1154 probe to the other end.
1157 @item PingTimeout = <@var{seconds}> (5)
1158 The number of seconds to wait for a response to pings or to allow meta
1159 connections to block. If the other end doesn't respond within this time,
1160 the connection is terminated, and the others will be notified of this.
1162 @cindex PriorityInheritance
1163 @item PriorityInheritance = <yes|no> (no) [experimental]
1164 When this option is enabled the value of the TOS field of tunneled IPv4 packets
1165 will be inherited by the UDP packets that are sent out.
1168 @item PrivateKey = <@var{key}> [obsolete]
1169 This is the RSA private key for tinc. However, for safety reasons it is
1170 advised to store private keys of any kind in separate files. This prevents
1171 accidental eavesdropping if you are editting the configuration file.
1173 @cindex PrivateKeyFile
1174 @item PrivateKeyFile = <@var{path}> (@file{@value{sysconfdir}/tinc/@var{netname}/rsa_key.priv})
1175 This is the full path name of the RSA private key file that was
1176 generated by @samp{tinc generate-keys}. It must be a full path, not a
1179 @cindex ProcessPriority
1180 @item ProcessPriority = <low|normal|high>
1181 When this option is used the priority of the tincd process will be adjusted.
1182 Increasing the priority may help to reduce latency and packet loss on the VPN.
1185 @item Proxy = socks4 | socks5 | http | exec @var{...} [experimental]
1186 Use a proxy when making outgoing connections.
1187 The following proxy types are currently supported:
1191 @item socks4 <@var{address}> <@var{port}> [<@var{username}>]
1192 Connects to the proxy using the SOCKS version 4 protocol.
1193 Optionally, a @var{username} can be supplied which will be passed on to the proxy server.
1196 @item socks5 <@var{address}> <@var{port}> [<@var{username}> <@var{password}>]
1197 Connect to the proxy using the SOCKS version 5 protocol.
1198 If a @var{username} and @var{password} are given, basic username/password authentication will be used,
1199 otherwise no authentication will be used.
1202 @item http <@var{address}> <@var{port}>
1203 Connects to the proxy and sends a HTTP CONNECT request.
1206 @item exec <@var{command}>
1207 Executes the given command which should set up the outgoing connection.
1208 The environment variables @env{NAME}, @env{NODE}, @env{REMOTEADDRES} and @env{REMOTEPORT} are available.
1211 @cindex ReplayWindow
1212 @item ReplayWindow = <bytes> (32)
1213 This is the size of the replay tracking window for each remote node, in bytes.
1214 The window is a bitfield which tracks 1 packet per bit, so for example
1215 the default setting of 32 will track up to 256 packets in the window. In high
1216 bandwidth scenarios, setting this to a higher value can reduce packet loss from
1217 the interaction of replay tracking with underlying real packet loss and/or
1218 reordering. Setting this to zero will disable replay tracking completely and
1219 pass all traffic, but leaves tinc vulnerable to replay-based attacks on your
1222 @cindex StrictSubnets
1223 @item StrictSubnets = <yes|no> (no) [experimental]
1224 When this option is enabled tinc will only use Subnet statements which are
1225 present in the host config files in the local
1226 @file{@value{sysconfdir}/tinc/@var{netname}/hosts/} directory.
1227 Subnets learned via connections to other nodes and which are not
1228 present in the local host config files are ignored.
1230 @cindex TunnelServer
1231 @item TunnelServer = <yes|no> (no) [experimental]
1232 When this option is enabled tinc will no longer forward information between other tinc daemons,
1233 and will only allow connections with nodes for which host config files are present in the local
1234 @file{@value{sysconfdir}/tinc/@var{netname}/hosts/} directory.
1235 Setting this options also implicitly sets StrictSubnets.
1238 @item UDPDiscovery = <yes|no> (yes)
1239 When this option is enabled tinc will try to establish UDP connectivity to nodes,
1240 using TCP while it determines if a node is reachable over UDP. If it is disabled,
1241 tinc always assumes a node is reachable over UDP.
1242 Note that tinc will never use UDP with nodes that have TCPOnly enabled.
1244 @cindex UDPDiscoveryKeepaliveInterval
1245 @item UDPDiscoveryKeepaliveInterval = <seconds> (9)
1246 The minimum amount of time between sending UDP ping datagrams to check UDP connectivity once it has been established.
1247 Note that these pings are large, since they are used to verify link MTU as well.
1249 @cindex UDPDiscoveryInterval
1250 @item UDPDiscoveryInterval = <seconds> (2)
1251 The minimum amount of time between sending UDP ping datagrams to try to establish UDP connectivity.
1253 @cindex UDPDiscoveryTimeout
1254 @item UDPDiscoveryTimeout = <seconds> (30)
1255 If tinc doesn't receive any UDP ping replies over the specified interval,
1256 it will assume UDP communication is broken and will fall back to TCP.
1258 @cindex UDPInfoInterval
1259 @item UDPInfoInterval = <seconds> (5)
1260 The minimum amount of time between sending periodic updates about UDP addresses, which are mostly useful for UDP hole punching.
1263 @item UDPRcvBuf = <bytes> (1048576)
1264 Sets the socket receive buffer size for the UDP socket, in bytes.
1265 If set to zero, the default buffer size will be used by the operating system.
1266 Note: this setting can have a significant impact on performance, especially raw throughput.
1269 @item UDPSndBuf = <bytes> (1048576)
1270 Sets the socket send buffer size for the UDP socket, in bytes.
1271 If set to zero, the default buffer size will be used by the operating system.
1272 Note: this setting can have a significant impact on performance, especially raw throughput.
1275 @item UPnP = <yes|udponly|no> (no)
1276 If this option is enabled then tinc will search for UPnP-IGD devices on the local network.
1277 It will then create and maintain port mappings for tinc's listening TCP and UDP ports.
1278 If set to "udponly", tinc will only create a mapping for its UDP (data) port, not for its TCP (metaconnection) port.
1279 Note that tinc must have been built with miniupnpc support for this feature to be available.
1280 Furthermore, be advised that enabling this can have security implications, because the miniupnpc library that
1281 tinc uses might not be well-hardened with regard to malicious UPnP replies.
1283 @cindex UPnPDiscoverWait
1284 @item UPnPDiscoverWait = <seconds> (5)
1285 The amount of time to wait for replies when probing the local network for UPnP devices.
1287 @cindex UPnPRefreshPeriod
1288 @item UPnPRefreshPeriod = <seconds> (5)
1289 How often tinc will re-add the port mapping, in case it gets reset on the UPnP device.
1290 This also controls the duration of the port mapping itself, which will be set to twice that duration.
1295 @c ==================================================================
1296 @node Host configuration variables
1297 @subsection Host configuration variables
1301 @item Address = <@var{IP address}|@var{hostname}> [<port>] [recommended]
1302 This variable is only required if you want to connect to this host. It
1303 must resolve to the external IP address where the host can be reached,
1304 not the one that is internal to the VPN.
1305 If no port is specified, the default Port is used.
1306 Multiple Address variables can be specified, in which case each address will be
1307 tried until a working connection has been established.
1310 @item Cipher = <@var{cipher}> (blowfish)
1311 The symmetric cipher algorithm used to encrypt UDP packets using the legacy protocol.
1312 Any cipher supported by LibreSSL or OpenSSL is recognized.
1313 Furthermore, specifying "none" will turn off packet encryption.
1314 It is best to use only those ciphers which support CBC mode.
1315 This option has no effect for connections using the SPTPS protocol, which always use AES-256-CTR.
1318 @item ClampMSS = <yes|no> (yes)
1319 This option specifies whether tinc should clamp the maximum segment size (MSS)
1320 of TCP packets to the path MTU. This helps in situations where ICMP
1321 Fragmentation Needed or Packet too Big messages are dropped by firewalls.
1324 @item Compression = <@var{level}> (0)
1325 This option sets the level of compression used for UDP packets.
1326 Possible values are 0 (off), 1 (fast zlib) and any integer up to 9 (best zlib),
1327 10 (fast lzo) and 11 (best lzo).
1330 @item Digest = <@var{digest}> (sha1)
1331 The digest algorithm used to authenticate UDP packets using the legacy protocol.
1332 Any digest supported by LibreSSL or OpenSSL is recognized.
1333 Furthermore, specifying "none" will turn off packet authentication.
1334 This option has no effect for connections using the SPTPS protocol, which always use HMAC-SHA-256.
1336 @cindex IndirectData
1337 @item IndirectData = <yes|no> (no)
1338 When set to yes, other nodes which do not already have a meta connection to you
1339 will not try to establish direct communication with you.
1340 It is best to leave this option out or set it to no.
1343 @item MACLength = <@var{bytes}> (4)
1344 The length of the message authentication code used to authenticate UDP packets using the legacy protocol.
1345 Can be anything from 0
1346 up to the length of the digest produced by the digest algorithm.
1347 This option has no effect for connections using the SPTPS protocol, which never truncate MACs.
1350 @item PMTU = <@var{mtu}> (1514)
1351 This option controls the initial path MTU to this node.
1353 @cindex PMTUDiscovery
1354 @item PMTUDiscovery = <yes|no> (yes)
1355 When this option is enabled, tinc will try to discover the path MTU to this node.
1356 After the path MTU has been discovered, it will be enforced on the VPN.
1358 @cindex MTUInfoInterval
1359 @item MTUInfoInterval = <seconds> (5)
1360 The minimum amount of time between sending periodic updates about relay path MTU. Useful for quickly determining MTU to indirect nodes.
1363 @item Port = <@var{port}> (655)
1364 This is the port this tinc daemon listens on.
1365 You can use decimal portnumbers or symbolic names (as listed in @file{/etc/services}).
1368 @item PublicKey = <@var{key}> [obsolete]
1369 This is the RSA public key for this host.
1371 @cindex PublicKeyFile
1372 @item PublicKeyFile = <@var{path}> [obsolete]
1373 This is the full path name of the RSA public key file that was generated
1374 by @samp{tinc generate-keys}. It must be a full path, not a relative
1378 From version 1.0pre4 on tinc will store the public key directly into the
1379 host configuration file in PEM format, the above two options then are not
1380 necessary. Either the PEM format is used, or exactly
1381 @strong{one of the above two options} must be specified
1382 in each host configuration file, if you want to be able to establish a
1383 connection with that host.
1386 @item Subnet = <@var{address}[/@var{prefixlength}[#@var{weight}]]>
1387 The subnet which this tinc daemon will serve.
1388 Tinc tries to look up which other daemon it should send a packet to by searching the appropiate subnet.
1389 If the packet matches a subnet,
1390 it will be sent to the daemon who has this subnet in his host configuration file.
1391 Multiple subnet lines can be specified for each daemon.
1393 Subnets can either be single MAC, IPv4 or IPv6 addresses,
1394 in which case a subnet consisting of only that single address is assumed,
1395 or they can be a IPv4 or IPv6 network address with a prefixlength.
1396 For example, IPv4 subnets must be in a form like 192.168.1.0/24,
1397 where 192.168.1.0 is the network address and 24 is the number of bits set in the netmask.
1398 Note that subnets like 192.168.1.1/24 are invalid!
1399 Read a networking HOWTO/FAQ/guide if you don't understand this.
1400 IPv6 subnets are notated like fec0:0:0:1::/64.
1401 MAC addresses are notated like 0:1a:2b:3c:4d:5e.
1403 @cindex CIDR notation
1404 Prefixlength is the number of bits set to 1 in the netmask part; for
1405 example: netmask 255.255.255.0 would become /24, 255.255.252.0 becomes
1406 /22. This conforms to standard CIDR notation as described in
1407 @uref{https://www.ietf.org/rfc/rfc1519.txt, RFC1519}
1409 A Subnet can be given a weight to indicate its priority over identical Subnets
1410 owned by different nodes. The default weight is 10. Lower values indicate
1411 higher priority. Packets will be sent to the node with the highest priority,
1412 unless that node is not reachable, in which case the node with the next highest
1413 priority will be tried, and so on.
1416 @item TCPonly = <yes|no> (no)
1417 If this variable is set to yes, then the packets are tunnelled over a
1418 TCP connection instead of a UDP connection. This is especially useful
1419 for those who want to run a tinc daemon from behind a masquerading
1420 firewall, or if UDP packet routing is disabled somehow.
1421 Setting this options also implicitly sets IndirectData.
1424 @item Weight = <weight>
1425 If this variable is set, it overrides the weight given to connections made with
1426 another host. A higher weight means a lower priority is given to this
1427 connection when broadcasting or forwarding packets.
1431 @c ==================================================================
1436 Apart from reading the server and host configuration files,
1437 tinc can also run scripts at certain moments.
1438 Below is a list of filenames of scripts and a description of when they are run.
1439 A script is only run if it exists and if it is executable.
1441 Scripts are run synchronously;
1442 this means that tinc will temporarily stop processing packets until the called script finishes executing.
1443 This guarantees that scripts will execute in the exact same order as the events that trigger them.
1444 If you need to run commands asynchronously, you have to ensure yourself that they are being run in the background.
1446 Under Windows (not Cygwin), the scripts should have the extension @file{.bat} or @file{.cmd}.
1450 @item @value{sysconfdir}/tinc/@var{netname}/tinc-up
1451 This is the most important script.
1452 If it is present it will be executed right after the tinc daemon has been
1453 started and has connected to the virtual network device.
1454 It should be used to set up the corresponding network interface,
1455 but can also be used to start other things.
1457 Under Windows you can use the Network Connections control panel instead of creating this script.
1460 @item @value{sysconfdir}/tinc/@var{netname}/tinc-down
1461 This script is started right before the tinc daemon quits.
1463 @item @value{sysconfdir}/tinc/@var{netname}/hosts/@var{host}-up
1464 This script is started when the tinc daemon with name @var{host} becomes reachable.
1466 @item @value{sysconfdir}/tinc/@var{netname}/hosts/@var{host}-down
1467 This script is started when the tinc daemon with name @var{host} becomes unreachable.
1469 @item @value{sysconfdir}/tinc/@var{netname}/host-up
1470 This script is started when any host becomes reachable.
1472 @item @value{sysconfdir}/tinc/@var{netname}/host-down
1473 This script is started when any host becomes unreachable.
1475 @item @value{sysconfdir}/tinc/@var{netname}/subnet-up
1476 This script is started when a Subnet becomes reachable.
1477 The Subnet and the node it belongs to are passed in environment variables.
1479 @item @value{sysconfdir}/tinc/@var{netname}/subnet-down
1480 This script is started when a Subnet becomes unreachable.
1482 @item @value{sysconfdir}/tinc/@var{netname}/invitation-created
1483 This script is started when a new invitation has been created.
1485 @item @value{sysconfdir}/tinc/@var{netname}/invitation-accepted
1486 This script is started when an invitation has been used.
1490 @cindex environment variables
1491 The scripts are started without command line arguments,
1492 but can make use of certain environment variables.
1493 Under UNIX like operating systems the names of environment variables must be preceded by a $ in scripts.
1494 Under Windows, in @file{.bat} or @file{.cmd} files, they have to be put between % signs.
1499 If a netname was specified, this environment variable contains it.
1503 Contains the name of this tinc daemon.
1507 Contains the name of the virtual network device that tinc uses.
1511 Contains the name of the virtual network interface that tinc uses.
1512 This should be used for commands like ifconfig.
1516 When a host becomes (un)reachable, this is set to its name.
1517 If a subnet becomes (un)reachable, this is set to the owner of that subnet.
1519 @cindex REMOTEADDRESS
1521 When a host becomes (un)reachable, this is set to its real address.
1525 When a host becomes (un)reachable,
1526 this is set to the port number it uses for communication with other tinc daemons.
1530 When a subnet becomes (un)reachable, this is set to the subnet.
1534 When a subnet becomes (un)reachable, this is set to the subnet weight.
1536 @cindex INVITATION_FILE
1537 @item INVITATION_FILE
1538 When the @file{invitation-created} script is called,
1539 this is set to the file where the invitation details will be stored.
1541 @cindex INVITATION_URL
1542 @item INVITATION_URL
1543 When the @file{invitation-created} script is called,
1544 this is set to the invitation URL that has been created.
1547 Do not forget that under UNIX operating systems,
1548 you have to make the scripts executable, using the command @samp{chmod a+x script}.
1551 @c ==================================================================
1552 @node How to configure
1553 @subsection How to configure
1555 @subsubheading Step 1. Creating initial configuration files.
1557 The initial directory structure, configuration files and public/private keypairs are created using the following command:
1560 tinc -n @var{netname} init @var{name}
1563 (You will need to run this as root, or use "sudo".)
1564 This will create the configuration directory @file{@value{sysconfdir}/tinc/@var{netname}.},
1565 and inside it will create another directory named @file{hosts/}.
1566 In the configuration directory, it will create the file @file{tinc.conf} with the following contents:
1572 It will also create private RSA and Ed25519 keys, which will be stored in the files @file{rsa_key.priv} and @file{ed25519_key.priv}.
1573 It will also create a host configuration file @file{hosts/@var{name}},
1574 which will contain the corresponding public RSA and Ed25519 keys.
1576 Finally, on UNIX operating systems, it will create an executable script @file{tinc-up},
1577 which will initially not do anything except warning that you should edit it.
1579 @subsubheading Step 2. Modifying the initial configuration.
1581 Unless you want to use tinc in switch mode,
1582 you should now configure which range of addresses you will use on the VPN.
1583 Let's assume you will be part of a VPN which uses the address range 192.168.0.0/16,
1584 and you yourself have a smaller portion of that range: 192.168.2.0/24.
1585 Then you should run the following command:
1588 tinc -n @var{netname} add subnet 192.168.2.0/24
1591 This will add a Subnet statement to your host configuration file.
1592 Try opening the file @file{@value{sysconfdir}/tinc/@var{netname}/hosts/@var{name}} in an editor.
1593 You should now see a file containing the public RSA and Ed25519 keys (which looks like a bunch of random characters),
1594 and the following line at the bottom:
1597 Subnet = 192.168.2.0/24
1600 If you will use more than one address range, you can add more Subnets.
1601 For example, if you also use the IPv6 subnet fec0:0:0:2::/64, you can add it as well:
1604 tinc -n @var{netname} add subnet fec0:0:0:2::/24
1607 This will add another line to the file @file{hosts/@var{name}}.
1608 If you make a mistake, you can undo it by simply using @samp{del} instead of @samp{add}.
1610 If you want other tinc daemons to create meta-connections to your daemon,
1611 you should add your public IP address or hostname to your host configuration file.
1612 For example, if your hostname is foo.example.org, run:
1615 tinc -n @var{netname} add address foo.example.org
1618 If you already know to which daemons your daemon should make meta-connections,
1619 you should configure that now as well.
1620 Suppose you want to connect to a daemon named "bar", run:
1623 tinc -n @var{netname} add connectto bar
1626 Note that you specify the Name of the other daemon here, not an IP address or hostname!
1627 When you start tinc, and it tries to make a connection to "bar",
1628 it will look for a host configuration file named @file{hosts/bar},
1629 and will read Address statements and public keys from that file.
1631 @subsubheading Step 2. Exchanging configuration files.
1633 If your daemon has a ConnectTo = bar statement in its @file{tinc.conf} file,
1634 or if bar has a ConnectTo your daemon, then you both need each other's host configuration files.
1635 You should send @file{hosts/@var{name}} to bar, and bar should send you his file which you should move to @file{hosts/bar}.
1636 If you are on a UNIX platform, you can easily send an email containing the necessary information using the following command
1637 (assuming the owner of bar has the email address bar@@example.org):
1640 tinc -n @var{netname} export | mail -s "My config file" bar@@example.org
1643 If the owner of bar does the same to send his host configuration file to you,
1644 you can probably pipe his email through the following command,
1645 or you can just start this command in a terminal and copy&paste the email:
1648 tinc -n @var{netname} import
1651 If you are the owner of bar yourself, and you have SSH access to that computer,
1652 you can also swap the host configuration files using the following command:
1655 tinc -n @var{netname} export \
1656 | ssh bar.example.org tinc -n @var{netname} exchange \
1657 | tinc -n @var{netname} import
1660 You should repeat this for all nodes you ConnectTo, or which ConnectTo you.
1661 However, remember that you do not need to ConnectTo all nodes in the VPN;
1662 it is only necessary to create one or a few meta-connections,
1663 after the connections are made tinc will learn about all the other nodes in the VPN,
1664 and will automatically make other connections as necessary.
1667 @c ==================================================================
1668 @node Network interfaces
1669 @section Network interfaces
1671 Before tinc can start transmitting data over the tunnel, it must
1672 set up the virtual network interface.
1674 First, decide which IP addresses you want to have associated with these
1675 devices, and what network mask they must have.
1677 Tinc will open a virtual network device (@file{/dev/tun}, @file{/dev/tap0} or similar),
1678 which will also create a network interface called something like @samp{tun0}, @samp{tap0}.
1679 If you are using the Linux tun/tap driver, the network interface will by default have the same name as the @var{netname}.
1680 Under Windows you can change the name of the network interface from the Network Connections control panel.
1683 You can configure the network interface by putting ordinary ifconfig, route, and other commands
1684 to a script named @file{@value{sysconfdir}/tinc/@var{netname}/tinc-up}.
1685 When tinc starts, this script will be executed. When tinc exits, it will execute the script named
1686 @file{@value{sysconfdir}/tinc/@var{netname}/tinc-down}, but normally you don't need to create that script.
1687 You can manually open the script in an editor, or use the following command:
1690 tinc -n @var{netname} edit tinc-up
1693 An example @file{tinc-up} script, that would be appropriate for the scenario in the previous section, is:
1697 ifconfig $INTERFACE 192.168.2.1 netmask 255.255.0.0
1698 ip addr add fec0:0:0:2::/48 dev $INTERFACE
1701 The first command gives the interface an IPv4 address and a netmask.
1702 The kernel will also automatically add an IPv4 route to this interface, so normally you don't need
1703 to add route commands to the @file{tinc-up} script.
1704 The kernel will also bring the interface up after this command.
1706 The netmask is the mask of the @emph{entire} VPN network, not just your
1708 The second command gives the interface an IPv6 address and netmask,
1709 which will also automatically add an IPv6 route.
1710 If you only want to use "ip addr" commands on Linux, don't forget that it doesn't bring the interface up, unlike ifconfig,
1711 so you need to add @samp{ip link set $INTERFACE up} in that case.
1713 The exact syntax of the ifconfig and route commands differs from platform to platform.
1714 You can look up the commands for setting addresses and adding routes in @ref{Platform specific information},
1715 but it is best to consult the manpages of those utilities on your platform.
1718 @c ==================================================================
1719 @node Example configuration
1720 @section Example configuration
1724 Imagine the following situation. Branch A of our example `company' wants to connect
1725 three branch offices in B, C and D using the Internet. All four offices
1726 have a 24/7 connection to the Internet.
1728 A is going to serve as the center of the network. B and C will connect
1729 to A, and D will connect to C. Each office will be assigned their own IP
1733 A: net 10.1.0.0 mask 255.255.0.0 gateway 10.1.54.1 internet IP 1.2.3.4
1734 B: net 10.2.0.0 mask 255.255.0.0 gateway 10.2.1.12 internet IP 2.3.4.5
1735 C: net 10.3.0.0 mask 255.255.0.0 gateway 10.3.69.254 internet IP 3.4.5.6
1736 D: net 10.4.0.0 mask 255.255.0.0 gateway 10.4.3.32 internet IP 4.5.6.7
1739 Here, ``gateway'' is the VPN IP address of the machine that is running the
1740 tincd, and ``internet IP'' is the IP address of the firewall, which does not
1741 need to run tincd, but it must do a port forwarding of TCP and UDP on port
1742 655 (unless otherwise configured).
1744 In this example, it is assumed that eth0 is the interface that points to
1745 the inner (physical) LAN of the office, although this could also be the
1746 same as the interface that leads to the Internet. The configuration of
1747 the real interface is also shown as a comment, to give you an idea of
1748 how these example host is set up. All branches use the netname `company'
1749 for this particular VPN.
1751 Each branch is set up using the @samp{tinc init} and @samp{tinc config} commands,
1752 here we just show the end results:
1754 @subsubheading For Branch A
1756 @emph{BranchA} would be configured like this:
1758 In @file{@value{sysconfdir}/tinc/company/tinc-up}:
1763 # Real interface of internal network:
1764 # ifconfig eth0 10.1.54.1 netmask 255.255.0.0
1766 ifconfig $INTERFACE 10.1.54.1 netmask 255.0.0.0
1769 and in @file{@value{sysconfdir}/tinc/company/tinc.conf}:
1775 On all hosts, @file{@value{sysconfdir}/tinc/company/hosts/BranchA} contains:
1778 Subnet = 10.1.0.0/16
1781 -----BEGIN RSA PUBLIC KEY-----
1783 -----END RSA PUBLIC KEY-----
1786 Note that the IP addresses of eth0 and the VPN interface are the same.
1787 This is quite possible, if you make sure that the netmasks of the interfaces are different.
1788 It is in fact recommended to give both real internal network interfaces and VPN interfaces the same IP address,
1789 since that will make things a lot easier to remember and set up.
1792 @subsubheading For Branch B
1794 In @file{@value{sysconfdir}/tinc/company/tinc-up}:
1799 # Real interface of internal network:
1800 # ifconfig eth0 10.2.43.8 netmask 255.255.0.0
1802 ifconfig $INTERFACE 10.2.1.12 netmask 255.0.0.0
1805 and in @file{@value{sysconfdir}/tinc/company/tinc.conf}:
1812 Note here that the internal address (on eth0) doesn't have to be the
1813 same as on the VPN interface. Also, ConnectTo is given so that this node will
1814 always try to connect to BranchA.
1816 On all hosts, in @file{@value{sysconfdir}/tinc/company/hosts/BranchB}:
1819 Subnet = 10.2.0.0/16
1822 -----BEGIN RSA PUBLIC KEY-----
1824 -----END RSA PUBLIC KEY-----
1828 @subsubheading For Branch C
1830 In @file{@value{sysconfdir}/tinc/company/tinc-up}:
1835 # Real interface of internal network:
1836 # ifconfig eth0 10.3.69.254 netmask 255.255.0.0
1838 ifconfig $INTERFACE 10.3.69.254 netmask 255.0.0.0
1841 and in @file{@value{sysconfdir}/tinc/company/tinc.conf}:
1848 C already has another daemon that runs on port 655, so they have to
1849 reserve another port for tinc. It knows the portnumber it has to listen on
1850 from it's own host configuration file.
1852 On all hosts, in @file{@value{sysconfdir}/tinc/company/hosts/BranchC}:
1856 Subnet = 10.3.0.0/16
1859 -----BEGIN RSA PUBLIC KEY-----
1861 -----END RSA PUBLIC KEY-----
1865 @subsubheading For Branch D
1867 In @file{@value{sysconfdir}/tinc/company/tinc-up}:
1872 # Real interface of internal network:
1873 # ifconfig eth0 10.4.3.32 netmask 255.255.0.0
1875 ifconfig $INTERFACE 10.4.3.32 netmask 255.0.0.0
1878 and in @file{@value{sysconfdir}/tinc/company/tinc.conf}:
1885 D will be connecting to C, which has a tincd running for this network on
1886 port 2000. It knows the port number from the host configuration file.
1888 On all hosts, in @file{@value{sysconfdir}/tinc/company/hosts/BranchD}:
1891 Subnet = 10.4.0.0/16
1894 -----BEGIN RSA PUBLIC KEY-----
1896 -----END RSA PUBLIC KEY-----
1899 @subsubheading Key files
1901 A, B, C and D all have their own public/private keypairs:
1903 The private RSA key is stored in @file{@value{sysconfdir}/tinc/company/rsa_key.priv},
1904 the private Ed25519 key is stored in @file{@value{sysconfdir}/tinc/company/ed25519_key.priv},
1905 and the public RSA and Ed25519 keys are put into the host configuration file in the @file{@value{sysconfdir}/tinc/company/hosts/} directory.
1907 @subsubheading Starting
1909 After each branch has finished configuration and they have distributed
1910 the host configuration files amongst them, they can start their tinc daemons.
1911 They don't necessarily have to wait for the other branches to have started
1912 their daemons, tinc will try connecting until they are available.
1915 @c ==================================================================
1917 @chapter Running tinc
1919 If everything else is done, you can start tinc by typing the following command:
1922 tinc -n @var{netname} start
1926 Tinc will detach from the terminal and continue to run in the background like a good daemon.
1927 If there are any problems however you can try to increase the debug level
1928 and look in the syslog to find out what the problems are.
1934 * Solving problems::
1936 * Sending bug reports::
1940 @c ==================================================================
1941 @node Runtime options
1942 @section Runtime options
1944 Besides the settings in the configuration file, tinc also accepts some
1945 command line options.
1947 @cindex command line
1948 @cindex runtime options
1952 @item -c, --config=@var{path}
1953 Read configuration options from the directory @var{path}. The default is
1954 @file{@value{sysconfdir}/tinc/@var{netname}/}.
1956 @item -D, --no-detach
1957 Don't fork and detach.
1958 This will also disable the automatic restart mechanism for fatal errors.
1961 @item -d, --debug=@var{level}
1962 Set debug level to @var{level}. The higher the debug level, the more gets
1963 logged. Everything goes via syslog.
1965 @item -n, --net=@var{netname}
1966 Use configuration for net @var{netname}.
1967 This will let tinc read all configuration files from
1968 @file{@value{sysconfdir}/tinc/@var{netname}/}.
1969 Specifying . for @var{netname} is the same as not specifying any @var{netname}.
1970 @xref{Multiple networks}.
1972 @item --pidfile=@var{filename}
1973 Store a cookie in @var{filename} which allows tinc to authenticate.
1974 If unspecified, the default is
1975 @file{@value{localstatedir}/run/tinc.@var{netname}.pid}.
1977 @item -o, --option=[@var{HOST}.]@var{KEY}=@var{VALUE}
1978 Without specifying a @var{HOST}, this will set server configuration variable @var{KEY} to @var{VALUE}.
1979 If specified as @var{HOST}.@var{KEY}=@var{VALUE},
1980 this will set the host configuration variable @var{KEY} of the host named @var{HOST} to @var{VALUE}.
1981 This option can be used more than once to specify multiple configuration variables.
1984 Lock tinc into main memory.
1985 This will prevent sensitive data like shared private keys to be written to the system swap files/partitions.
1987 This option is not supported on all platforms.
1989 @item --logfile[=@var{file}]
1990 Write log entries to a file instead of to the system logging facility.
1991 If @var{file} is omitted, the default is @file{@value{localstatedir}/log/tinc.@var{netname}.log}.
1993 @item --bypass-security
1994 Disables encryption and authentication.
1995 Only useful for debugging.
1998 Change process root directory to the directory where the config file is
1999 located (@file{@value{sysconfdir}/tinc/@var{netname}/} as determined by
2000 -n/--net option or as given by -c/--config option), for added security.
2001 The chroot is performed after all the initialization is done, after
2002 writing pid files and opening network sockets.
2004 Note that this option alone does not do any good without -U/--user, below.
2006 Note also that tinc can't run scripts anymore (such as tinc-down or host-up),
2007 unless it's setup to be runnable inside chroot environment.
2009 This option is not supported on all platforms.
2010 @item -U, --user=@var{user}
2011 Switch to the given @var{user} after initialization, at the same time as
2012 chroot is performed (see --chroot above). With this option tinc drops
2013 privileges, for added security.
2015 This option is not supported on all platforms.
2018 Display a short reminder of these runtime options and terminate.
2021 Output version information and exit.
2025 @c ==================================================================
2030 You can also send the following signals to a running tincd process:
2036 Forces tinc to try to connect to all uplinks immediately.
2037 Usually tinc attempts to do this itself,
2038 but increases the time it waits between the attempts each time it failed,
2039 and if tinc didn't succeed to connect to an uplink the first time after it started,
2040 it defaults to the maximum time of 15 minutes.
2043 Partially rereads configuration files.
2044 Connections to hosts whose host config file are removed are closed.
2045 New outgoing connections specified in @file{tinc.conf} will be made.
2046 If the --logfile option is used, this will also close and reopen the log file,
2047 useful when log rotation is used.
2051 @c ==================================================================
2053 @section Debug levels
2055 @cindex debug levels
2056 The tinc daemon can send a lot of messages to the syslog.
2057 The higher the debug level, the more messages it will log.
2058 Each level inherits all messages of the previous level:
2064 This will log a message indicating tinc has started along with a version number.
2065 It will also log any serious error.
2068 This will log all connections that are made with other tinc daemons.
2071 This will log status and error messages from scripts and other tinc daemons.
2074 This will log all requests that are exchanged with other tinc daemons. These include
2075 authentication, key exchange and connection list updates.
2078 This will log a copy of everything received on the meta socket.
2081 This will log all network traffic over the virtual private network.
2085 @c ==================================================================
2086 @node Solving problems
2087 @section Solving problems
2089 If tinc starts without problems, but if the VPN doesn't work, you will have to find the cause of the problem.
2090 The first thing to do is to start tinc with a high debug level in the foreground,
2091 so you can directly see everything tinc logs:
2094 tincd -n @var{netname} -d5 -D
2097 If tinc does not log any error messages, then you might want to check the following things:
2100 @item @file{tinc-up} script
2101 Does this script contain the right commands?
2102 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.
2105 Does the Subnet (or Subnets) in the host configuration file of this host match the portion of the VPN that belongs to this host?
2107 @item Firewalls and NATs
2108 Do you have a firewall or a NAT device (a masquerading firewall or perhaps an ADSL router that performs masquerading)?
2109 If so, check that it allows TCP and UDP traffic on port 655.
2110 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.
2111 You can add @samp{TCPOnly = yes} to your host config file to force tinc to only use a single TCP connection,
2112 this works through most firewalls and NATs.
2117 @c ==================================================================
2118 @node Error messages
2119 @section Error messages
2121 What follows is a list of the most common error messages you might find in the logs.
2122 Some of them will only be visible if the debug level is high enough.
2125 @item Could not open /dev/tap0: No such device
2128 @item You forgot to `modprobe netlink_dev' or `modprobe ethertap'.
2129 @item You forgot to compile `Netlink device emulation' in the kernel.
2132 @item Can't write to /dev/net/tun: No such device
2135 @item You forgot to `modprobe tun'.
2136 @item You forgot to compile `Universal TUN/TAP driver' in the kernel.
2137 @item The tun device is located somewhere else in @file{/dev/}.
2140 @item Network address and prefix length do not match!
2143 @item The Subnet field must contain a @emph{network} address, trailing bits should be 0.
2144 @item If you only want to use one IP address, set the netmask to /32.
2147 @item Error reading RSA key file `rsa_key.priv': No such file or directory
2150 @item You forgot to create a public/private keypair.
2151 @item Specify the complete pathname to the private key file with the @samp{PrivateKeyFile} option.
2154 @item Warning: insecure file permissions for RSA private key file `rsa_key.priv'!
2157 @item The private key file is readable by users other than root.
2158 Use chmod to correct the file permissions.
2161 @item Creating metasocket failed: Address family not supported
2164 @item By default tinc tries to create both IPv4 and IPv6 sockets.
2165 On some platforms this might not be implemented.
2166 If the logs show @samp{Ready} later on, then at least one metasocket was created,
2167 and you can ignore this message.
2168 You can add @samp{AddressFamily = ipv4} to @file{tinc.conf} to prevent this from happening.
2171 @item Cannot route packet: unknown IPv4 destination 1.2.3.4
2174 @item You try to send traffic to a host on the VPN for which no Subnet is known.
2175 @item If it is a broadcast address (ending in .255), it probably is a samba server or a Windows host sending broadcast packets.
2179 @item Cannot route packet: ARP request for unknown address 1.2.3.4
2182 @item You try to send traffic to a host on the VPN for which no Subnet is known.
2185 @item Packet with destination 1.2.3.4 is looping back to us!
2188 @item Something is not configured right. Packets are being sent out to the
2189 virtual network device, but according to the Subnet directives in your host configuration
2190 file, those packets should go to your own host. Most common mistake is that
2191 you have a Subnet line in your host configuration file with a prefix length which is
2192 just as large as the prefix of the virtual network interface. The latter should in almost all
2193 cases be larger. Rethink your configuration.
2194 Note that you will only see this message if you specified a debug
2195 level of 5 or higher!
2196 @item Chances are that a @samp{Subnet = ...} line in the host configuration file of this tinc daemon is wrong.
2197 Change it to a subnet that is accepted locally by another interface,
2198 or if that is not the case, try changing the prefix length into /32.
2201 @item Node foo (1.2.3.4) is not reachable
2204 @item Node foo does not have a connection anymore, its tinc daemon is not running or its connection to the Internet is broken.
2207 @item Received UDP packet from unknown source 1.2.3.4 (port 12345)
2210 @item If you see this only sporadically, it is harmless and caused by a node sending packets using an old key.
2211 @item 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.
2212 You can add @samp{TCPOnly = yes} to host configuration files to force all VPN traffic to go over a TCP connection.
2215 @item Got bad/bogus/unauthorized REQUEST from foo (1.2.3.4 port 12345)
2218 @item Node foo does not have the right public/private keypair.
2219 Generate new keypairs and distribute them again.
2220 @item An attacker tries to gain access to your VPN.
2221 @item A network error caused corruption of metadata sent from foo.
2226 @c ==================================================================
2227 @node Sending bug reports
2228 @section Sending bug reports
2230 If you really can't find the cause of a problem, or if you suspect tinc is not working right,
2231 you can send us a bugreport, see @ref{Contact information}.
2232 Be sure to include the following information in your bugreport:
2235 @item A clear description of what you are trying to achieve and what the problem is.
2236 @item What platform (operating system, version, hardware architecture) and which version of tinc you use.
2237 @item If compiling tinc fails, a copy of @file{config.log} and the error messages you get.
2238 @item Otherwise, a copy of @file{tinc.conf}, @file{tinc-up} and all files in the @file{hosts/} directory.
2239 @item The output of the commands @samp{ifconfig -a} and @samp{route -n} (or @samp{netstat -rn} if that doesn't work).
2240 @item The output of any command that fails to work as it should (like ping or traceroute).
2243 @c ==================================================================
2244 @node Controlling tinc
2245 @chapter Controlling tinc
2247 @cindex command line interface
2248 You can start, stop, control and inspect a running tincd through the tinc
2249 command. A quick example:
2252 tinc -n @var{netname} reload
2256 If tinc is started without a command, it will act as a shell; it will display a
2257 prompt, and commands can be entered on the prompt. If tinc is compiled with
2258 libreadline, history and command completion are available on the prompt. One
2259 can also pipe a script containing commands through tinc. In that case, lines
2260 starting with a # symbol will be ignored.
2263 * tinc runtime options::
2264 * tinc environment variables::
2271 @c ==================================================================
2272 @node tinc runtime options
2273 @section tinc runtime options
2277 @item -c, --config=@var{path}
2278 Read configuration options from the directory @var{path}. The default is
2279 @file{@value{sysconfdir}/tinc/@var{netname}/}.
2281 @item -n, --net=@var{netname}
2282 Use configuration for net @var{netname}. @xref{Multiple networks}.
2284 @item --pidfile=@var{filename}
2285 Use the cookie from @var{filename} to authenticate with a running tinc daemon.
2286 If unspecified, the default is
2287 @file{@value{localstatedir}/run/tinc.@var{netname}.pid}.
2290 Force some commands to work despite warnings.
2293 Display a short reminder of runtime options and commands, then terminate.
2296 Output version information and exit.
2300 @c ==================================================================
2301 @node tinc environment variables
2302 @section tinc environment variables
2307 If no netname is specified on the command line with the @option{-n} option,
2308 the value of this environment variable is used.
2311 @c ==================================================================
2313 @section tinc commands
2319 @item init [@var{name}]
2320 Create initial configuration files and RSA and Ed25519 keypairs with default length.
2321 If no @var{name} for this node is given, it will be asked for.
2324 @item get @var{variable}
2325 Print the current value of configuration variable @var{variable}.
2326 If more than one variable with the same name exists,
2327 the value of each of them will be printed on a separate line.
2330 @item set @var{variable} @var{value}
2331 Set configuration variable @var{variable} to the given @var{value}.
2332 All previously existing configuration variables with the same name are removed.
2333 To set a variable for a specific host, use the notation @var{host}.@var{variable}.
2336 @item add @var{variable} @var{value}
2337 As above, but without removing any previously existing configuration variables.
2338 If the variable already exists with the given value, nothing happens.
2341 @item del @var{variable} [@var{value}]
2342 Remove configuration variables with the same name and @var{value}.
2343 If no @var{value} is given, all configuration variables with the same name will be removed.
2346 @item edit @var{filename}
2347 Start an editor for the given configuration file.
2348 You do not need to specify the full path to the file.
2352 Export the host configuration file of the local node to standard output.
2356 Export all host configuration files to standard output.
2360 Import host configuration file(s) generated by the tinc export command from standard input.
2361 Already existing host configuration files are not overwritten unless the option --force is used.
2365 The same as export followed by import.
2367 @cindex exchange-all
2369 The same as export-all followed by import.
2372 @item invite @var{name}
2373 Prepares an invitation for a new node with the given @var{name},
2374 and prints a short invitation URL that can be used with the join command.
2377 @item join [@var{URL}]
2378 Join an existing VPN using an invitation URL created using the invite command.
2379 If no @var{URL} is given, it will be read from standard input.
2382 @item start [tincd options]
2383 Start @samp{tincd}, optionally with the given extra options.
2390 @item restart [tincd options]
2391 Restart @samp{tincd}, optionally with the given extra options.
2395 Partially rereads configuration files. Connections to hosts whose host
2396 config files are removed are closed. New outgoing connections specified
2397 in @file{tinc.conf} will be made.
2401 Shows the PID of the currently running @samp{tincd}.
2403 @cindex generate-keys
2404 @item generate-keys [@var{bits}]
2405 Generate both RSA and Ed25519 keypairs (see below) and exit.
2406 tinc will ask where you want to store the files, but will default to the
2407 configuration directory (you can use the -c or -n option).
2409 @cindex generate-ed25519-keys
2410 @item generate-ed25519-keys
2411 Generate public/private Ed25519 keypair and exit.
2413 @cindex generate-rsa-keys
2414 @item generate-rsa-keys [@var{bits}]
2415 Generate public/private RSA keypair and exit. If @var{bits} is omitted, the
2416 default length will be 2048 bits. When saving keys to existing files, tinc
2417 will not delete the old keys; you have to remove them manually.
2420 @item dump [reachable] nodes
2421 Dump a list of all known nodes in the VPN.
2422 If the reachable keyword is used, only lists reachable nodes.
2425 Dump a list of all known connections in the VPN.
2428 Dump a list of all known subnets in the VPN.
2430 @item dump connections
2431 Dump a list of all meta connections with ourself.
2434 @item dump graph | digraph
2435 Dump a graph of the VPN in dotty format.
2436 Nodes are colored according to their reachability:
2437 red nodes are unreachable, orange nodes are indirectly reachable, green nodes are directly reachable.
2438 Black nodes are either directly or indirectly reachable, but direct reachability has not been tried yet.
2440 @item dump invitations
2441 Dump a list of outstanding invitations.
2442 The filename of the invitation, as well as the name of the node that is being invited is shown for each invitation.
2445 @item info @var{node} | @var{subnet} | @var{address}
2446 Show information about a particular @var{node}, @var{subnet} or @var{address}.
2447 If an @var{address} is given, any matching subnet will be shown.
2451 Purges all information remembered about unreachable nodes.
2454 @item debug @var{level}
2455 Sets debug level to @var{level}.
2458 @item log [@var{level}]
2459 Capture log messages from a running tinc daemon.
2460 An optional debug level can be given that will be applied only for log messages sent to tinc.
2464 Forces tinc to try to connect to all uplinks immediately.
2465 Usually tinc attempts to do this itself,
2466 but increases the time it waits between the attempts each time it failed,
2467 and if tinc didn't succeed to connect to an uplink the first time after it started,
2468 it defaults to the maximum time of 15 minutes.
2471 @item disconnect @var{node}
2472 Closes the meta connection with the given @var{node}.
2476 If tinc is compiled with libcurses support, this will display live traffic statistics for all the known nodes,
2477 similar to the UNIX top command.
2478 See below for more information.
2482 Dump VPN traffic going through the local tinc node in pcap-savefile format to standard output,
2483 from where it can be redirected to a file or piped through a program that can parse it directly,
2487 @item network [@var{netname}]
2488 If @var{netname} is given, switch to that network.
2489 Otherwise, display a list of all networks for which configuration files exist.
2493 This will check the configuration files for possible problems,
2494 such as unsafe file permissions, missing executable bit on script,
2495 unknown and obsolete configuration variables, wrong public and/or private keys, and so on.
2497 When problems are found, this will be printed on a line with WARNING or ERROR in front of it.
2498 Most problems must be corrected by the user itself, however in some cases (like file permissions and missing public keys),
2499 tinc will ask if it should fix the problem.
2502 @item sign [@var{filename}]
2503 Sign a file with the local node's private key.
2504 If no @var{filename} is given, the file is read from standard input.
2505 The signed file is written to standard output.
2508 @item verify @var{name} [@var{filename}]
2510 Check the signature of a file against a node's public key.
2511 The @var{name} of the node must be given,
2512 or can be "." to check against the local node's public key,
2513 or "*" to allow a signature from any node whose public key is known.
2514 If no @var{filename} is given, the file is read from standard input.
2515 If the verification is succesful, a copy of the input with the signature removed is written to standard output, and the exit code will be zero.
2516 If the verification failed, nothing will be written to standard output, and the exit code will be non-zero.
2520 @c ==================================================================
2522 @section tinc examples
2524 Examples of some commands:
2527 tinc -n vpn dump graph | circo -Txlib
2528 tinc -n vpn pcap | tcpdump -r -
2532 Examples of changing the configuration using tinc:
2535 tinc -n vpn init foo
2536 tinc -n vpn add Subnet 192.168.1.0/24
2537 tinc -n vpn add bar.Address bar.example.com
2538 tinc -n vpn add ConnectTo bar
2539 tinc -n vpn export | gpg --clearsign | mail -s "My config" vpnmaster@@example.com
2542 @c ==================================================================
2547 The top command connects to a running tinc daemon and repeatedly queries its per-node traffic counters.
2548 It displays a list of all the known nodes in the left-most column,
2549 and the amount of bytes and packets read from and sent to each node in the other columns.
2550 By default, the information is updated every second.
2551 The behaviour of the top command can be changed using the following keys:
2556 Change the interval between updates.
2557 After pressing the @key{s} key, enter the desired interval in seconds, followed by enter.
2558 Fractional seconds are honored.
2559 Intervals lower than 0.1 seconds are not allowed.
2562 Toggle between displaying current traffic rates (in packets and bytes per second)
2563 and cummulative traffic (total packets and bytes since the tinc daemon started).
2566 Sort the list of nodes by name.
2569 Sort the list of nodes by incoming amount of bytes.
2572 Sort the list of nodes by incoming amount of packets.
2575 Sort the list of nodes by outgoing amount of bytes.
2578 Sort the list of nodes by outgoing amount of packets.
2581 Sort the list of nodes by sum of incoming and outgoing amount of bytes.
2584 Sort the list of nodes by sum of incoming and outgoing amount of packets.
2587 Show amount of traffic in bytes.
2590 Show amount of traffic in kilobytes.
2593 Show amount of traffic in megabytes.
2596 Show amount of traffic in gigabytes.
2604 @c ==================================================================
2606 @chapter Invitations
2608 Invitations are an easy way to add new nodes to an existing VPN. Invitations
2609 can be created on an existing node using the @code{tinc invite} command, which
2610 generates a relatively short URL which can be given to someone else, who uses
2611 the @code{tinc join} command to automatically set up tinc so it can connect to
2612 the inviting node. The next sections describe how invitations actually work,
2613 and how to further automate the invitations.
2616 * How invitations work::
2617 * Invitation file format::
2618 * Writing an invitation-created script::
2622 @c ==================================================================
2623 @node How invitations work
2624 @section How invitations work
2626 When an invitation is created on a node (which from now on we will call the
2627 server) using the @code{tinc invite} command, an invitation file is created
2628 that contains all the information necessary for the invitee (which we will call
2629 the client) to create its configuration files. The invitation file is stays on
2630 the server, but a URL is generated that has enough information for the client
2631 to contact the server and to retrieve the invitation file. The whole URL is
2632 around 80 characters long and looks like this:
2635 server.example.org:12345/cW1NhLHS-1WPFlcFio8ztYHvewTTKYZp8BjEKg3vbMtDz7w4
2638 It is composed of four parts:
2641 hostname : port / keyhash cookie
2644 The hostname and port tell the client how to reach the tinc daemon on the server.
2645 The part after the slash looks like one blob, but is composed of two parts.
2646 The keyhash is the hash of the public key of the server.
2647 The cookie is a shared secret that identifies the client to the server.
2649 When the client connects to the server in order to join the VPN, the client and
2650 server will exchange temporary public keys. The client verifies that the hash
2651 of the server's public key matches the keyhash from the invitation URL. If
2652 not, it will immediately exit with an error. Otherwise, an ECDH exchange will
2653 happen so the client and server can communicate privately with each other. The
2654 client will then present the cookie to the server. The server uses this to
2655 look up the corresponding invitation file it generated earlier. If it exists,
2656 it will send the invitation file to the client. The client will also create a
2657 permanent public key, and send it to the server. After the exchange is
2658 completed, the connection is broken. The server creates a host config file for
2659 the client containing the client's permanent public key, and the client creates
2660 tinc.conf, host config files and possibly a tinc-up script based on the
2661 information in the invitation file.
2663 It is important that the invitation URL is kept secret until it is used; if
2664 another person gets a copy of the invitation URL before the real client runs
2665 the @code{tinc join} command, then that other person can try to join the VPN.
2668 @c ==================================================================
2669 @node Invitation file format
2670 @section Invitation file format
2672 The contents of an invitation file that is generated by the @code{tinc invite}
2673 command looks like this:
2679 #-------------------------------------#
2681 Ed25519PublicKey = augbnwegoij123587...
2682 Address = server.example.com
2685 The file is basically a concatenation of several host config blocks. Each host
2686 config block starts with @code{Name = ...}. Lines that look like @code{#---#}
2687 are not important, it just makes it easier for humans to read the file.
2689 The first host config block is always the one representing the invitee. So the
2690 first Name statement determines the name that the invitee will get. From the
2691 first block, the @file{tinc.conf} and @file{hosts/client} files will be
2692 generated; the @code{tinc join} command on the client will automatically
2693 separate statements based on whether they should be in @file{tinc.conf} or in a
2694 host config file. Some statements are special and are treated differently:
2697 @item Netname = <@var{netname}>
2698 This is a hint to the invitee which netname to use for the VPN. It is used if
2699 the invitee did not already specify a netname, and if there is no pre-existing
2700 configuration with the same netname.
2703 @item Ifconfig = <@var{address}[/@var{netmask}] | dhcp | dhcp6 | slaac>
2704 This is a hint for generating a @file{tinc-up} script.
2705 If an address is specified, a command will be added to @file{tinc-up} so the VPN interface will be configured to have the given address.
2706 If it is the word "dhcp", a command will be added to start a DHCP client on the VPN interface.
2707 If it is the word dhcpv6, it will be a DHCPv6 client.
2708 If it is "slaac", then it will add commands to enable IPv6 stateless address autoconfiguration.
2709 It is also possible to specify a MAC address, in which case a command will be added to set the MAC address of the VPN interface.
2711 The exact commands added to the @file{tinc-up} script depends on the operating system the client is using.
2712 Multiple Ifconfig statements can be specified, however one should only use one Ifconfig statement per address family.
2715 @item Route = <@var{address}[/@var{netmask}]> [<@var{gateway}>]
2716 This is a hint for generating a @file{tinc-up} script.
2717 Route statements are similar to Ifconfig statements, but add routes instead of addresses.
2718 These only allow IPv4 and IPv6 routes.
2719 If no gateway address is specified, the route is directed to the VPN interface.
2720 In general, a gateway is only necessary when running tinc in switch mode.
2723 Subsequent host config blocks are copied verbatim into their respective files
2724 in @file{hosts/}. The invitation file generated by @code{tinc invite} will
2725 normally only contain two blocks; one for the client and one for the server.
2728 @c ==================================================================
2729 @node Writing an invitation-created script
2730 @section Writing an invitation-created script
2732 When an invitation is generated, the "invitation-created" script is called (if
2733 it exists) right after the invitation file is written, but before the URL has
2734 been written to stdout. This allows one to change the invitation file
2735 automatically before the invitation URL is passed to the invitee. Here is an
2736 example shell script that aproximately recreates the default invitation file:
2741 cat >$INVITATION_FILE <<EOF
2748 tinc export >>$INVITATION_FILE
2751 You can add more ConnectTo statements, and change `tinc export` to `tinc
2752 export-all` for example. But you can also use the script to automatically hand
2753 out a Subnet to the invitee. Note that the script doesn't have to be a shell script,
2754 you can use any language, it just has to be executable.
2757 @c ==================================================================
2758 @node Technical information
2759 @chapter Technical information
2764 * The meta-protocol::
2769 @c ==================================================================
2770 @node The connection
2771 @section The connection
2774 Tinc is a daemon that takes VPN data and transmit that to another host
2775 computer over the existing Internet infrastructure.
2779 * The meta-connection::
2783 @c ==================================================================
2784 @node The UDP tunnel
2785 @subsection The UDP tunnel
2787 @cindex virtual network device
2789 The data itself is read from a character device file, the so-called
2790 @emph{virtual network device}. This device is associated with a network
2791 interface. Any data sent to this interface can be read from the device,
2792 and any data written to the device gets sent from the interface.
2793 There are two possible types of virtual network devices:
2794 `tun' style, which are point-to-point devices which can only handle IPv4 and/or IPv6 packets,
2795 and `tap' style, which are Ethernet devices and handle complete Ethernet frames.
2797 So when tinc reads an Ethernet frame from the device, it determines its
2798 type. When tinc is in it's default routing mode, it can handle IPv4 and IPv6
2799 packets. Depending on the Subnet lines, it will send the packets off to their destination IP address.
2800 In the `switch' and `hub' mode, tinc will use broadcasts and MAC address discovery
2801 to deduce the destination of the packets.
2802 Since the latter modes only depend on the link layer information,
2803 any protocol that runs over Ethernet is supported (for instance IPX and Appletalk).
2804 However, only `tap' style devices provide this information.
2806 After the destination has been determined,
2807 the packet will be compressed (optionally),
2808 a sequence number will be added to the packet,
2809 the packet will then be encrypted
2810 and a message authentication code will be appended.
2812 @cindex encapsulating
2814 When that is done, time has come to actually transport the
2815 packet to the destination computer. We do this by sending the packet
2816 over an UDP connection to the destination host. This is called
2817 @emph{encapsulating}, the VPN packet (though now encrypted) is
2818 encapsulated in another IP datagram.
2820 When the destination receives this packet, the same thing happens, only
2821 in reverse. So it checks the message authentication code, decrypts the contents of the UDP datagram,
2822 checks the sequence number
2823 and writes the decrypted information to its own virtual network device.
2825 If the virtual network device is a `tun' device (a point-to-point tunnel),
2826 there is no problem for the kernel to accept a packet.
2827 However, if it is a `tap' device (this is the only available type on FreeBSD),
2828 the destination MAC address must match that of the virtual network interface.
2829 If tinc is in it's default routing mode, ARP does not work, so the correct destination MAC
2830 can not be known by the sending host.
2831 Tinc solves this by letting the receiving end detect the MAC address of its own virtual network interface
2832 and overwriting the destination MAC address of the received packet.
2834 In switch or hub modes ARP does work so the sender already knows the correct destination MAC address.
2835 In those modes every interface should have a unique MAC address, so make sure they are not the same.
2836 Because switch and hub modes rely on MAC addresses to function correctly,
2837 these modes cannot be used on the following operating systems which don't have a `tap' style virtual network device:
2838 OpenBSD, NetBSD, Darwin and Solaris.
2841 @c ==================================================================
2842 @node The meta-connection
2843 @subsection The meta-connection
2845 Having only a UDP connection available is not enough. Though suitable
2846 for transmitting data, we want to be able to reliably send other
2847 information, such as routing and session key information to somebody.
2850 TCP is a better alternative, because it already contains protection
2851 against information being lost, unlike UDP.
2853 So we establish two connections. One for the encrypted VPN data, and one
2854 for other information, the meta-data. Hence, we call the second
2855 connection the meta-connection. We can now be sure that the
2856 meta-information doesn't get lost on the way to another computer.
2858 @cindex data-protocol
2859 @cindex meta-protocol
2860 Like with any communication, we must have a protocol, so that everybody
2861 knows what everything stands for, and how she should react. Because we
2862 have two connections, we also have two protocols. The protocol used for
2863 the UDP data is the ``data-protocol,'' the other one is the
2866 The reason we don't use TCP for both protocols is that UDP is much
2867 better for encapsulation, even while it is less reliable. The real
2868 problem is that when TCP would be used to encapsulate a TCP stream
2869 that's on the private network, for every packet sent there would be
2870 three ACKs sent instead of just one. Furthermore, if there would be
2871 a timeout, both TCP streams would sense the timeout, and both would
2872 start re-sending packets.
2875 @c ==================================================================
2876 @node The meta-protocol
2877 @section The meta-protocol
2879 The meta protocol is used to tie all tinc daemons together, and
2880 exchange information about which tinc daemon serves which virtual
2883 The meta protocol consists of requests that can be sent to the other
2884 side. Each request has a unique number and several parameters. All
2885 requests are represented in the standard ASCII character set. It is
2886 possible to use tools such as telnet or netcat to connect to a tinc
2887 daemon started with the --bypass-security option
2888 and to read and write requests by hand, provided that one
2889 understands the numeric codes sent.
2891 The authentication scheme is described in @ref{Security}. After a
2892 successful authentication, the server and the client will exchange all the
2893 information about other tinc daemons and subnets they know of, so that both
2894 sides (and all the other tinc daemons behind them) have their information
2901 ------------------------------------------------------------------
2902 ADD_EDGE node1 node2 21.32.43.54 655 222 0
2903 | | | | | +-> options
2904 | | | | +----> weight
2905 | | | +--------> UDP port of node2
2906 | | +----------------> real address of node2
2907 | +-------------------------> name of destination node
2908 +-------------------------------> name of source node
2910 ADD_SUBNET node 192.168.1.0/24
2911 | | +--> prefixlength
2912 | +--------> network address
2913 +------------------> owner of this subnet
2914 ------------------------------------------------------------------
2917 The ADD_EDGE messages are to inform other tinc daemons that a connection between
2918 two nodes exist. The address of the destination node is available so that
2919 VPN packets can be sent directly to that node.
2921 The ADD_SUBNET messages inform other tinc daemons that certain subnets belong
2922 to certain nodes. tinc will use it to determine to which node a VPN packet has
2929 ------------------------------------------------------------------
2930 DEL_EDGE node1 node2
2931 | +----> name of destination node
2932 +----------> name of source node
2934 DEL_SUBNET node 192.168.1.0/24
2935 | | +--> prefixlength
2936 | +--------> network address
2937 +------------------> owner of this subnet
2938 ------------------------------------------------------------------
2941 In case a connection between two daemons is closed or broken, DEL_EDGE messages
2942 are sent to inform the other daemons of that fact. Each daemon will calculate a
2943 new route to the the daemons, or mark them unreachable if there isn't any.
2950 ------------------------------------------------------------------
2951 REQ_KEY origin destination
2952 | +--> name of the tinc daemon it wants the key from
2953 +----------> name of the daemon that wants the key
2955 ANS_KEY origin destination 4ae0b0a82d6e0078 91 64 4
2956 | | \______________/ | | +--> MAC length
2957 | | | | +-----> digest algorithm
2958 | | | +--------> cipher algorithm
2959 | | +--> 128 bits key
2960 | +--> name of the daemon that wants the key
2961 +----------> name of the daemon that uses this key
2964 +--> daemon that has changed it's packet key
2965 ------------------------------------------------------------------
2968 The keys used to encrypt VPN packets are not sent out directly. This is
2969 because it would generate a lot of traffic on VPNs with many daemons, and
2970 chances are that not every tinc daemon will ever send a packet to every
2971 other daemon. Instead, if a daemon needs a key it sends a request for it
2972 via the meta connection of the nearest hop in the direction of the
2979 ------------------------------------------------------------------
2982 ------------------------------------------------------------------
2985 There is also a mechanism to check if hosts are still alive. Since network
2986 failures or a crash can cause a daemon to be killed without properly
2987 shutting down the TCP connection, this is necessary to keep an up to date
2988 connection list. PINGs are sent at regular intervals, except when there
2989 is also some other traffic. A little bit of salt (random data) is added
2990 with each PING and PONG message, to make sure that long sequences of PING/PONG
2991 messages without any other traffic won't result in known plaintext.
2993 This basically covers what is sent over the meta connection by tinc.
2996 @c ==================================================================
3002 Tinc got its name from ``TINC,'' short for @emph{There Is No Cabal}; the
3003 alleged Cabal was/is an organisation that was said to keep an eye on the
3004 entire Internet. As this is exactly what you @emph{don't} want, we named
3005 the tinc project after TINC.
3008 But in order to be ``immune'' to eavesdropping, you'll have to encrypt
3009 your data. Because tinc is a @emph{Secure} VPN (SVPN) daemon, it does
3010 exactly that: encrypt.
3011 However, encryption in itself does not prevent an attacker from modifying the encrypted data.
3012 Therefore, tinc also authenticates the data.
3013 Finally, tinc uses sequence numbers (which themselves are also authenticated) to prevent an attacker from replaying valid packets.
3015 Since version 1.1pre3, tinc has two protocols used to protect your data; the legacy protocol, and the new Simple Peer-to-Peer Security (SPTPS) protocol.
3016 The SPTPS protocol is designed to address some weaknesses in the legacy protocol.
3017 The new authentication protocol is used when two nodes connect to each other that both have the ExperimentalProtocol option set to yes,
3018 otherwise the legacy protocol will be used.
3021 * Legacy authentication protocol::
3022 * Simple Peer-to-Peer Security::
3023 * Encryption of network packets::
3028 @c ==================================================================
3029 @node Legacy authentication protocol
3030 @subsection Legacy authentication protocol
3032 @cindex legacy authentication protocol
3041 --------------------------------------------------------------------------
3042 client <attempts connection>
3044 server <accepts connection>
3046 client ID client 17.2
3047 | | +-> minor protocol version
3048 | +----> major protocol version
3049 +--------> name of tinc daemon
3051 server ID server 17.2
3052 | | +-> minor protocol version
3053 | +----> major protocol version
3054 +--------> name of tinc daemon
3056 client META_KEY 94 64 0 0 5f0823a93e35b69e...7086ec7866ce582b
3057 | | | | \_________________________________/
3058 | | | | +-> RSAKEYLEN bits totally random string S1,
3059 | | | | encrypted with server's public RSA key
3060 | | | +-> compression level
3061 | | +---> MAC length
3062 | +------> digest algorithm NID
3063 +---------> cipher algorithm NID
3065 server META_KEY 94 64 0 0 6ab9c1640388f8f0...45d1a07f8a672630
3066 | | | | \_________________________________/
3067 | | | | +-> RSAKEYLEN bits totally random string S2,
3068 | | | | encrypted with client's public RSA key
3069 | | | +-> compression level
3070 | | +---> MAC length
3071 | +------> digest algorithm NID
3072 +---------> cipher algorithm NID
3073 --------------------------------------------------------------------------
3076 The protocol allows each side to specify encryption algorithms and parameters,
3077 but in practice they are always fixed, since older versions of tinc did not
3078 allow them to be different from the default values. The cipher is always
3079 Blowfish in OFB mode, the digest is SHA1, but the MAC length is zero and no
3080 compression is used.
3084 @item the client will symmetrically encrypt outgoing traffic using S1
3085 @item the server will symmetrically encrypt outgoing traffic using S2
3089 --------------------------------------------------------------------------
3090 client CHALLENGE da02add1817c1920989ba6ae2a49cecbda0
3091 \_________________________________/
3092 +-> CHALLEN bits totally random string H1
3094 server CHALLENGE 57fb4b2ccd70d6bb35a64c142f47e61d57f
3095 \_________________________________/
3096 +-> CHALLEN bits totally random string H2
3098 client CHAL_REPLY 816a86
3099 +-> 160 bits SHA1 of H2
3101 server CHAL_REPLY 928ffe
3102 +-> 160 bits SHA1 of H1
3104 After the correct challenge replies are received, both ends have proved
3105 their identity. Further information is exchanged.
3107 client ACK 655 123 0
3109 | +----> estimated weight
3110 +--------> listening port of client
3112 server ACK 655 321 0
3114 | +----> estimated weight
3115 +--------> listening port of server
3116 --------------------------------------------------------------------------
3119 This legacy authentication protocol has several weaknesses, pointed out by security export Peter Gutmann.
3120 First, data is encrypted with RSA without padding.
3121 Padding schemes are designed to prevent attacks when the size of the plaintext is not equal to the size of the RSA key.
3122 Tinc always encrypts random nonces that have the same size as the RSA key, so we do not believe this leads to a break of the security.
3123 There might be timing or other side-channel attacks against RSA encryption and decryption, tinc does not employ any protection against those.
3124 Furthermore, both sides send identical messages to each other, there is no distinction between server and client,
3125 which could make a MITM attack easier.
3126 However, no exploit is known in which a third party who is not already trusted by other nodes in the VPN could gain access.
3127 Finally, the RSA keys are used to directly encrypt the session keys, which means that if the RSA keys are compromised, it is possible to decrypt all previous VPN traffic.
3128 In other words, the legacy protocol does not provide perfect forward secrecy.
3130 @c ==================================================================
3131 @node Simple Peer-to-Peer Security
3132 @subsection Simple Peer-to-Peer Security
3135 The SPTPS protocol is designed to address the weaknesses in the legacy protocol.
3136 SPTPS is based on TLS 1.2, but has been simplified: there is no support for exchanging public keys, and there is no cipher suite negotiation.
3137 Instead, SPTPS always uses a very strong cipher suite:
3138 peers authenticate each other using 521 bits ECC keys,
3139 Diffie-Hellman using ephemeral 521 bits ECC keys is used to provide perfect forward secrecy (PFS),
3140 AES-256-CTR is used for encryption, and HMAC-SHA-256 for message authentication.
3142 Similar to TLS, messages are split up in records.
3143 A complete logical record contains the following information:
3146 @item uint32_t seqno (network byte order)
3147 @item uint16_t length (network byte order)
3149 @item opaque data[length]
3150 @item opaque hmac[HMAC_SIZE] (HMAC over all preceding fields)
3153 Depending on whether SPTPS records are sent via TCP or UDP, either the seqno or the length field is omitted on the wire
3154 (but they are still included in the calculation of the HMAC);
3155 for TCP packets are guaranteed to arrive in-order so we can infer the seqno, but packets can be split or merged, so we still need the length field to determine the boundaries between records;
3156 for UDP packets we know that there is exactly one record per packet, and we know the length of a packet, but packets can be dropped, duplicated and/or reordered, so we need to include the seqno.
3158 The type field is used to distinguish between application records or handshake records.
3159 Types 0 to 127 are application records, type 128 is a handshake record, and types 129 to 255 are reserved.
3161 Before the initial handshake, no fields are encrypted, and the HMAC field is not present.
3162 After the authentication handshake, the length (if present), type and data fields are encrypted, and the HMAC field is present.
3163 For UDP packets, the seqno field is not encrypted, as it is used to determine the value of the counter used for encryption.
3165 The authentication consists of an exchange of Key EXchange, SIGnature and ACKnowledge messages, transmitted using type 128 records.
3171 ---------------------
3177 ...encrypt and HMAC using session keys from now on...
3184 ...key renegotiation starts here...
3193 ...encrypt and HMAC using new session keys from now on...
3199 ---------------------
3202 Note that the responder does not need to wait before it receives the first KEX message,
3203 it can immediately send its own once it has accepted an incoming connection.
3205 Key EXchange message:
3208 @item uint8_t kex_version (always 0 in this version of SPTPS)
3209 @item opaque nonce[32] (random number)
3210 @item opaque ecdh_key[ECDH_SIZE]
3216 @item opaque ecdsa_signature[ECDSA_SIZE]
3219 ACKnowledge message:
3222 @item empty (only sent after key renegotiation)
3228 @item At the start, both peers generate a random nonce and an Elliptic Curve public key and send it to the other in the KEX message.
3229 @item After receiving the other's KEX message, both KEX messages are concatenated (see below),
3230 and the result is signed using ECDSA.
3231 The result is sent to the other.
3232 @item After receiving the other's SIG message, the signature is verified.
3233 If it is correct, the shared secret is calculated from the public keys exchanged in the KEX message using the Elliptic Curve Diffie-Helman algorithm.
3234 @item The shared secret key is expanded using a PRF.
3235 Both nonces and the application specific label are also used as input for the PRF.
3236 @item An ACK message is sent only when doing key renegotiation, and is sent using the old encryption keys.
3237 @item The expanded key is used to key the encryption and HMAC algorithms.
3240 The signature is calculated over this string:
3243 @item uint8_t initiator (0 = local peer, 1 = remote peer is initiator)
3244 @item opaque remote_kex_message[1 + 32 + ECDH_SIZE]
3245 @item opaque local_kex_message[1 + 32 + ECDH_SIZE]
3246 @item opaque label[label_length]
3249 The PRF is calculated as follows:
3252 @item A HMAC using SHA512 is used, the shared secret is used as the key.
3253 @item For each block of 64 bytes, a HMAC is calculated. For block n: hmac[n] =
3254 HMAC_SHA512(hmac[n - 1] + seed)
3255 @item For the first block (n = 1), hmac[0] is given by HMAC_SHA512(zeroes + seed),
3256 where zeroes is a block of 64 zero bytes.
3259 The seed is as follows:
3262 @item const char[13] "key expansion"
3263 @item opaque responder_nonce[32]
3264 @item opaque initiator_nonce[32]
3265 @item opaque label[label_length]
3268 The expanded key is used as follows:
3271 @item opaque responder_cipher_key[CIPHER_KEYSIZE]
3272 @item opaque responder_digest_key[DIGEST_KEYSIZE]
3273 @item opaque initiator_cipher_key[CIPHER_KEYSIZE]
3274 @item opaque initiator_digest_key[DIGEST_KEYSIZE]
3277 Where initiator_cipher_key is the key used by session initiator to encrypt
3278 messages sent to the responder.
3280 When using 256 bits Ed25519 keys, the AES-256-CTR cipher and HMAC-SHA-256 digest algorithm,
3281 the sizes are as follows:
3284 ECDH_SIZE: 32 (= 256/8)
3285 ECDSA_SIZE: 64 (= 2 * 256/8)
3286 CIPHER_KEYSIZE: 48 (= 256/8 + 128/8)
3287 DIGEST_KEYSIZE: 32 (= 256/8)
3290 Note that the cipher key also includes the initial value for the counter.
3292 @c ==================================================================
3293 @node Encryption of network packets
3294 @subsection Encryption of network packets
3297 A data packet can only be sent if the encryption key is known to both
3298 parties, and the connection is activated. If the encryption key is not
3299 known, a request is sent to the destination using the meta connection
3303 The UDP packets can be either encrypted with the legacy protocol or with SPTPS.
3304 In case of the legacy protocol, the UDP packet containing the network packet from the VPN has the following layout:
3307 ... | IP header | UDP header | seqno | VPN packet | MAC | UDP trailer
3308 \___________________/\_____/
3310 V +---> digest algorithm
3311 Encrypted with symmetric cipher
3317 So, the entire VPN packet is encrypted using a symmetric cipher, including a 32 bits
3318 sequence number that is added in front of the actual VPN packet, to act as a unique
3319 IV for each packet and to prevent replay attacks. A message authentication code
3320 is added to the UDP packet to prevent alteration of packets.
3321 Tinc by default encrypts network packets using Blowfish with 128 bit keys in CBC mode
3322 and uses 4 byte long message authentication codes to make sure
3323 eavesdroppers cannot get and cannot change any information at all from the
3324 packets they can intercept. The encryption algorithm and message authentication
3325 algorithm can be changed in the configuration. The length of the message
3326 authentication codes is also adjustable. The length of the key for the
3327 encryption algorithm is always the default length used by LibreSSL/OpenSSL.
3329 The SPTPS protocol is described in @ref{Simple Peer-to-Peer Security}.
3330 For comparison, this is how SPTPS UDP packets look:
3333 ... | IP header | UDP header | seqno | type | VPN packet | MAC | UDP trailer
3334 \__________________/\_____/
3336 V +---> digest algorithm
3337 Encrypted with symmetric cipher
3340 The difference is that the seqno is not encrypted, since the encryption cipher is used in CTR mode,
3341 and therefore the seqno must be known before the packet can be decrypted.
3342 Furthermore, the MAC is never truncated.
3343 The SPTPS protocol always uses the AES-256-CTR cipher and HMAC-SHA-256 digest,
3344 this cannot be changed.
3347 @c ==================================================================
3348 @node Security issues
3349 @subsection Security issues
3351 In August 2000, we discovered the existence of a security hole in all versions
3352 of tinc up to and including 1.0pre2. This had to do with the way we exchanged
3353 keys. Since then, we have been working on a new authentication scheme to make
3354 tinc as secure as possible. The current version uses the LibreSSL or OpenSSL library and
3355 uses strong authentication with RSA keys.
3357 On the 29th of December 2001, Jerome Etienne posted a security analysis of tinc
3358 1.0pre4. Due to a lack of sequence numbers and a message authentication code
3359 for each packet, an attacker could possibly disrupt certain network services or
3360 launch a denial of service attack by replaying intercepted packets. The current
3361 version adds sequence numbers and message authentication codes to prevent such
3364 On the 15th of September 2003, Peter Gutmann posted a security analysis of tinc
3365 1.0.1. He argues that the 32 bit sequence number used by tinc is not a good IV,
3366 that tinc's default length of 4 bytes for the MAC is too short, and he doesn't
3367 like tinc's use of RSA during authentication. We do not know of a security hole
3368 in the legacy protocol of tinc, but it is not as strong as TLS or IPsec.
3370 This version of tinc comes with an improved protocol, called Simple Peer-to-Peer Security,
3371 which aims to be as strong as TLS with one of the strongest cipher suites.
3373 Cryptography is a hard thing to get right. We cannot make any
3374 guarantees. Time, review and feedback are the only things that can
3375 prove the security of any cryptographic product. If you wish to review
3376 tinc or give us feedback, you are stronly encouraged to do so.
3379 @c ==================================================================
3380 @node Platform specific information
3381 @chapter Platform specific information
3384 * Interface configuration::
3388 @c ==================================================================
3389 @node Interface configuration
3390 @section Interface configuration
3392 When configuring an interface, one normally assigns it an address and a
3393 netmask. The address uniquely identifies the host on the network attached to
3394 the interface. The netmask, combined with the address, forms a subnet. It is
3395 used to add a route to the routing table instructing the kernel to send all
3396 packets which fall into that subnet to that interface. Because all packets for
3397 the entire VPN should go to the virtual network interface used by tinc, the
3398 netmask should be such that it encompasses the entire VPN.
3402 @multitable {Darwin (MacOS/X)} {ifconfig route add -bla network address netmask netmask prefixlength interface}
3404 @tab @code{ifconfig} @var{interface} @var{address} @code{netmask} @var{netmask}
3405 @item Linux iproute2
3406 @tab @code{ip addr add} @var{address}@code{/}@var{prefixlength} @code{dev} @var{interface}
3408 @tab @code{ifconfig} @var{interface} @var{address} @code{netmask} @var{netmask}
3410 @tab @code{ifconfig} @var{interface} @var{address} @code{netmask} @var{netmask}
3412 @tab @code{ifconfig} @var{interface} @var{address} @code{netmask} @var{netmask}
3414 @tab @code{ifconfig} @var{interface} @var{address} @code{netmask} @var{netmask}
3415 @item Darwin (MacOS/X)
3416 @tab @code{ifconfig} @var{interface} @var{address} @code{netmask} @var{netmask}
3418 @tab @code{netsh interface ip set address} @var{interface} @code{static} @var{address} @var{netmask}
3423 @multitable {Darwin (MacOS/X)} {ifconfig route add -bla network address netmask netmask prefixlength interface}
3425 @tab @code{ifconfig} @var{interface} @code{add} @var{address}@code{/}@var{prefixlength}
3427 @tab @code{ifconfig} @var{interface} @code{inet6} @var{address} @code{prefixlen} @var{prefixlength}
3429 @tab @code{ifconfig} @var{interface} @code{inet6} @var{address} @code{prefixlen} @var{prefixlength}
3431 @tab @code{ifconfig} @var{interface} @code{inet6} @var{address} @code{prefixlen} @var{prefixlength}
3433 @tab @code{ifconfig} @var{interface} @code{inet6 plumb up}
3435 @tab @code{ifconfig} @var{interface} @code{inet6 addif} @var{address} @var{address}
3436 @item Darwin (MacOS/X)
3437 @tab @code{ifconfig} @var{interface} @code{inet6} @var{address} @code{prefixlen} @var{prefixlength}
3439 @tab @code{netsh interface ipv6 add address} @var{interface} @code{static} @var{address}/@var{prefixlength}
3442 On some platforms, when running tinc in switch mode, the VPN interface must be set to tap mode with an ifconfig command:
3444 @multitable {Darwin (MacOS/X)} {ifconfig route add -bla network address netmask netmask prefixlength interface}
3446 @tab @code{ifconfig} @var{interface} @code{link0}
3449 On Linux, it is possible to create a persistent tun/tap interface which will
3450 continue to exist even if tinc quit, although this is normally not required.
3451 It can be useful to set up a tun/tap interface owned by a non-root user, so
3452 tinc can be started without needing any root privileges at all.
3454 @multitable {Darwin (MacOS/X)} {ifconfig route add -bla network address netmask netmask prefixlength interface}
3456 @tab @code{ip tuntap add dev} @var{interface} @code{mode} @var{tun|tap} @code{user} @var{username}
3459 @c ==================================================================
3463 In some cases it might be necessary to add more routes to the virtual network
3464 interface. There are two ways to indicate which interface a packet should go
3465 to, one is to use the name of the interface itself, another way is to specify
3466 the (local) address that is assigned to that interface (@var{local_address}). The
3467 former way is unambiguous and therefore preferable, but not all platforms
3470 Adding routes to IPv4 subnets:
3472 @multitable {Darwin (MacOS/X)} {ifconfig route add -bla network address netmask netmask prefixlength interface}
3474 @tab @code{route add -net} @var{network_address} @code{netmask} @var{netmask} @var{interface}
3475 @item Linux iproute2
3476 @tab @code{ip route add} @var{network_address}@code{/}@var{prefixlength} @code{dev} @var{interface}
3478 @tab @code{route add} @var{network_address}@code{/}@var{prefixlength} @var{local_address}
3480 @tab @code{route add} @var{network_address}@code{/}@var{prefixlength} @var{local_address}
3482 @tab @code{route add} @var{network_address}@code{/}@var{prefixlength} @var{local_address}
3484 @tab @code{route add} @var{network_address}@code{/}@var{prefixlength} @var{local_address} @code{-interface}
3485 @item Darwin (MacOS/X)
3486 @tab @code{route add} @var{network_address}@code{/}@var{prefixlength} @var{local_address}
3488 @tab @code{netsh routing ip add persistentroute} @var{network_address} @var{netmask} @var{interface} @var{local_address}
3491 Adding routes to IPv6 subnets:
3493 @multitable {Darwin (MacOS/X)} {ifconfig route add -bla network address netmask netmask prefixlength interface}
3495 @tab @code{route add -A inet6} @var{network_address}@code{/}@var{prefixlength} @var{interface}
3496 @item Linux iproute2
3497 @tab @code{ip route add} @var{network_address}@code{/}@var{prefixlength} @code{dev} @var{interface}
3499 @tab @code{route add -inet6} @var{network_address}@code{/}@var{prefixlength} @var{local_address}
3501 @tab @code{route add -inet6} @var{network_address} @var{local_address} @code{-prefixlen} @var{prefixlength}
3503 @tab @code{route add -inet6} @var{network_address} @var{local_address} @code{-prefixlen} @var{prefixlength}
3505 @tab @code{route add -inet6} @var{network_address}@code{/}@var{prefixlength} @var{local_address} @code{-interface}
3506 @item Darwin (MacOS/X)
3509 @tab @code{netsh interface ipv6 add route} @var{network address}/@var{prefixlength} @var{interface}
3513 @c ==================================================================
3519 * Contact information::
3524 @c ==================================================================
3525 @node Contact information
3526 @section Contact information
3529 Tinc's website is at @url{https://www.tinc-vpn.org/},
3530 this server is located in the Netherlands.
3533 We have an IRC channel on the FreeNode and OFTC IRC networks. Connect to
3534 @uref{https://freenode.net/, irc.freenode.net}
3536 @uref{https://www.oftc.net/, irc.oftc.net}
3537 and join channel #tinc.
3540 @c ==================================================================
3545 @item Ivo Timmermans (zarq)
3546 @item Guus Sliepen (guus) (@email{guus@@tinc-vpn.org})
3549 We have received a lot of valuable input from users. With their help,
3550 tinc has become the flexible and robust tool that it is today. We have
3551 composed a list of contributions, in the file called @file{THANKS} in
3552 the source distribution.
3555 @c ==================================================================
3557 @unnumbered Concept Index
3559 @c ==================================================================
3563 @c ==================================================================