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{} 1998-2015 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{} 1998-2015 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 ==================================================================
73 * Technical information::
74 * Platform specific information::
76 * Concept Index:: All used terms explained
80 @c ==================================================================
85 Tinc is a Virtual Private Network (VPN) daemon that uses tunneling and
86 encryption to create a secure private network between hosts on the
89 Because the tunnel appears to the IP level network code as a normal
90 network device, there is no need to adapt any existing software.
91 The encrypted tunnels allows VPN sites to share information with each other
92 over the Internet without exposing any information to others.
94 This document is the manual for tinc. Included are chapters on how to
95 configure your computer to use tinc, as well as the configuration
96 process of tinc itself.
99 * Virtual Private Networks::
101 * Supported platforms::
104 @c ==================================================================
105 @node Virtual Private Networks
106 @section Virtual Private Networks
109 A Virtual Private Network or VPN is a network that can only be accessed
110 by a few elected computers that participate. This goal is achievable in
111 more than just one way.
114 Private networks can consist of a single stand-alone Ethernet LAN. Or
115 even two computers hooked up using a null-modem cable. In these cases,
117 obvious that the network is @emph{private}, no one can access it from the
118 outside. But if your computers are linked to the Internet, the network
119 is not private anymore, unless one uses firewalls to block all private
120 traffic. But then, there is no way to send private data to trusted
121 computers on the other end of the Internet.
124 This problem can be solved by using @emph{virtual} networks. Virtual
125 networks can live on top of other networks, but they use encapsulation to
126 keep using their private address space so they do not interfere with
127 the Internet. Mostly, virtual networks appear like a single LAN, even though
128 they can span the entire world. But virtual networks can't be secured
129 by using firewalls, because the traffic that flows through it has to go
130 through the Internet, where other people can look at it.
132 As is the case with either type of VPN, anybody could eavesdrop. Or
133 worse, alter data. Hence it's probably advisable to encrypt the data
134 that flows over the network.
136 When one introduces encryption, we can form a true VPN. Other people may
137 see encrypted traffic, but if they don't know how to decipher it (they
138 need to know the key for that), they cannot read the information that flows
139 through the VPN. This is what tinc was made for.
142 @c ==================================================================
147 I really don't quite remember what got us started, but it must have been
148 Guus' idea. He wrote a simple implementation (about 50 lines of C) that
149 used the ethertap device that Linux knows of since somewhere
150 about kernel 2.1.60. It didn't work immediately and he improved it a
151 bit. At this stage, the project was still simply called "vpnd".
153 Since then, a lot has changed---to say the least.
156 Tinc now supports encryption, it consists of a single daemon (tincd) for
157 both the receiving and sending end, it has become largely
158 runtime-configurable---in short, it has become a full-fledged
159 professional package.
161 @cindex traditional VPNs
163 Tinc also allows more than two sites to connect to eachother and form a single VPN.
164 Traditionally VPNs are created by making tunnels, which only have two endpoints.
165 Larger VPNs with more sites are created by adding more tunnels.
166 Tinc takes another approach: only endpoints are specified,
167 the software itself will take care of creating the tunnels.
168 This allows for easier configuration and improved scalability.
170 A lot can---and will be---changed. We have a number of things that we would like to
171 see in the future releases of tinc. Not everything will be available in
172 the near future. Our first objective is to make tinc work perfectly as
173 it stands, and then add more advanced features.
175 Meanwhile, we're always open-minded towards new ideas. And we're
179 @c ==================================================================
180 @node Supported platforms
181 @section Supported platforms
184 Tinc has been verified to work under Linux, FreeBSD, OpenBSD, NetBSD, MacOS/X (Darwin), Solaris, and Windows (both natively and in a Cygwin environment),
185 with various hardware architectures. These are some of the platforms
186 that are supported by the universal tun/tap device driver or other virtual network device drivers.
187 Without such a driver, tinc will most
188 likely compile and run, but it will not be able to send or receive data
192 For an up to date list of supported platforms, please check the list on
194 @uref{http://www.tinc-vpn.org/platforms/}.
202 @c Preparing your system
209 @c ==================================================================
211 @chapter Preparations
213 This chapter contains information on how to prepare your system to
217 * Configuring the kernel::
222 @c ==================================================================
223 @node Configuring the kernel
224 @section Configuring the kernel
227 * Configuration of Linux kernels::
228 * Configuration of FreeBSD kernels::
229 * Configuration of OpenBSD kernels::
230 * Configuration of NetBSD kernels::
231 * Configuration of Solaris kernels::
232 * Configuration of Darwin (MacOS/X) kernels::
233 * Configuration of Windows::
237 @c ==================================================================
238 @node Configuration of Linux kernels
239 @subsection Configuration of Linux kernels
241 @cindex Universal tun/tap
242 For tinc to work, you need a kernel that supports the Universal tun/tap device.
243 Most distributions come with kernels that already support this.
244 Here are the options you have to turn on when configuring a new kernel:
247 Code maturity level options
248 [*] Prompt for development and/or incomplete code/drivers
249 Network device support
250 <M> Universal tun/tap device driver support
253 It's not necessary to compile this driver as a module, even if you are going to
254 run more than one instance of tinc.
256 If you decide to build the tun/tap driver as a kernel module, add these lines
257 to @file{/etc/modules.conf}:
260 alias char-major-10-200 tun
264 @c ==================================================================
265 @node Configuration of FreeBSD kernels
266 @subsection Configuration of FreeBSD kernels
268 For FreeBSD version 4.1 and higher, tun and tap drivers are included in the default kernel configuration.
269 The tap driver can be loaded with @code{kldload if_tap}, or by adding @code{if_tap_load="YES"} to @file{/boot/loader.conf}.
272 @c ==================================================================
273 @node Configuration of OpenBSD kernels
274 @subsection Configuration of OpenBSD kernels
276 For OpenBSD version 2.9 and higher,
277 the tun driver is included in the default kernel configuration.
278 There is also a kernel patch from @uref{http://diehard.n-r-g.com/stuff/openbsd/}
279 which adds a tap device to OpenBSD which should work with tinc,
280 but with recent versions of OpenBSD,
281 a tun device can act as a tap device by setting the link0 option with ifconfig.
284 @c ==================================================================
285 @node Configuration of NetBSD kernels
286 @subsection Configuration of NetBSD kernels
288 For NetBSD version 1.5.2 and higher,
289 the tun driver is included in the default kernel configuration.
291 Tunneling IPv6 may not work on NetBSD's tun device.
294 @c ==================================================================
295 @node Configuration of Solaris kernels
296 @subsection Configuration of Solaris kernels
298 For Solaris 8 (SunOS 5.8) and higher,
299 the tun driver may or may not be included in the default kernel configuration.
300 If it isn't, the source can be downloaded from @uref{http://vtun.sourceforge.net/tun/}.
301 For x86 and sparc64 architectures, precompiled versions can be found at @uref{http://www.monkey.org/~dugsong/fragroute/}.
302 If the @file{net/if_tun.h} header file is missing, install it from the source package.
305 @c ==================================================================
306 @node Configuration of Darwin (MacOS/X) kernels
307 @subsection Configuration of Darwin (MacOS/X) kernels
309 Tinc on Darwin relies on a tunnel driver for its data acquisition from the kernel.
310 OS X version 10.6.8 and later have a built-in tun driver called "utun".
311 Tinc also supports the driver from @uref{http://tuntaposx.sourceforge.net/},
312 which supports both tun and tap style devices,
314 By default, tinc expects the tuntaposx driver to be installed.
315 To use the utun driver, set add @code{Device = utunX} to @file{tinc.conf},
316 where X is the desired number for the utun interface.
317 You can also omit the number, in which case the first free number will be chosen.
320 @c ==================================================================
321 @node Configuration of Windows
322 @subsection Configuration of Windows
324 You will need to install the latest TAP-Win32 driver from OpenVPN.
325 You can download it from @uref{http://openvpn.sourceforge.net}.
326 Using the Network Connections control panel,
327 configure the TAP-Win32 network interface in the same way as you would do from the tinc-up script,
328 as explained in the rest of the documentation.
331 @c ==================================================================
337 Before you can configure or build tinc, you need to have the OpenSSL, zlib,
338 lzo, curses and readline libraries installed on your system. If you try to
339 configure tinc without having them installed, configure will give you an error
351 @c ==================================================================
356 For all cryptography-related functions, tinc uses the functions provided
357 by the OpenSSL library.
359 If this library is not installed, you wil get an error when configuring
360 tinc for build. Support for running tinc with other cryptographic libraries
361 installed @emph{may} be added in the future.
363 You can use your operating system's package manager to install this if
364 available. Make sure you install the development AND runtime versions
367 If you have to install OpenSSL manually, you can get the source code
368 from @url{http://www.openssl.org/}. Instructions on how to configure,
369 build and install this package are included within the package. Please
370 make sure you build development and runtime libraries (which is the
373 If you installed the OpenSSL libraries from source, it may be necessary
374 to let configure know where they are, by passing configure one of the
375 --with-openssl-* parameters.
378 --with-openssl=DIR OpenSSL library and headers prefix
379 --with-openssl-include=DIR OpenSSL headers directory
380 (Default is OPENSSL_DIR/include)
381 --with-openssl-lib=DIR OpenSSL library directory
382 (Default is OPENSSL_DIR/lib)
386 @subsubheading License
389 The complete source code of tinc is covered by the GNU GPL version 2.
390 Since the license under which OpenSSL is distributed is not directly
391 compatible with the terms of the GNU GPL
392 @uref{http://www.openssl.org/support/faq.html#LEGAL2}, we
393 include an exemption to the GPL (see also the file COPYING.README) to allow
394 everyone to create a statically or dynamically linked executable:
397 This program is released under the GPL with the additional exemption
398 that compiling, linking, and/or using OpenSSL is allowed. You may
399 provide binary packages linked to the OpenSSL libraries, provided that
400 all other requirements of the GPL are met.
403 Since the LZO library used by tinc is also covered by the GPL,
404 we also present the following exemption:
407 Hereby I grant a special exception to the tinc VPN project
408 (http://www.tinc-vpn.org/) to link the LZO library with the OpenSSL library
409 (http://www.openssl.org).
411 Markus F.X.J. Oberhumer
415 @c ==================================================================
420 For the optional compression of UDP packets, tinc uses the functions provided
423 If this library is not installed, you wil get an error when running the
424 configure script. You can either install the zlib library, or disable support
425 for zlib compression by using the "--disable-zlib" option when running the
426 configure script. Note that if you disable support for zlib, the resulting
427 binary will not work correctly on VPNs where zlib compression is used.
429 You can use your operating system's package manager to install this if
430 available. Make sure you install the development AND runtime versions
433 If you have to install zlib manually, you can get the source code
434 from @url{http://www.gzip.org/zlib/}. Instructions on how to configure,
435 build and install this package are included within the package. Please
436 make sure you build development and runtime libraries (which is the
440 @c ==================================================================
445 Another form of compression is offered using the LZO library.
447 If this library is not installed, you wil get an error when running the
448 configure script. You can either install the LZO library, or disable support
449 for LZO compression by using the "--disable-lzo" option when running the
450 configure script. Note that if you disable support for LZO, the resulting
451 binary will not work correctly on VPNs where LZO compression is used.
453 You can use your operating system's package manager to install this if
454 available. Make sure you install the development AND runtime versions
457 If you have to install lzo manually, you can get the source code
458 from @url{http://www.oberhumer.com/opensource/lzo/}. Instructions on how to configure,
459 build and install this package are included within the package. Please
460 make sure you build development and runtime libraries (which is the
464 @c ==================================================================
466 @subsection libcurses
469 For the "tinc top" command, tinc requires a curses library.
471 If this library is not installed, you wil get an error when running the
472 configure script. You can either install a suitable curses library, or disable
473 all functionality that depends on a curses library by using the
474 "--disable-curses" option when running the configure script.
476 There are several curses libraries. It is recommended that you install
477 "ncurses" (@url{http://invisible-island.net/ncurses/}),
478 however other curses libraries should also work.
479 In particular, "PDCurses" (@url{http://pdcurses.sourceforge.net/})
480 is recommended if you want to compile tinc for Windows.
482 You can use your operating system's package manager to install this if
483 available. Make sure you install the development AND runtime versions
487 @c ==================================================================
489 @subsection libreadline
492 For the "tinc" command's shell functionality, tinc uses the readline library.
494 If this library is not installed, you wil get an error when running the
495 configure script. You can either install a suitable readline library, or
496 disable all functionality that depends on a readline library by using the
497 "--disable-readline" option when running the configure script.
499 You can use your operating system's package manager to install this if
500 available. Make sure you install the development AND runtime versions
503 If you have to install libreadline manually, you can get the source code from
504 @url{http://www.gnu.org/software/readline/}. Instructions on how to configure,
505 build and install this package are included within the package. Please make
506 sure you build development and runtime libraries (which is the default).
518 @c ==================================================================
520 @chapter Installation
522 If you use Debian, you may want to install one of the
523 precompiled packages for your system. These packages are equipped with
524 system startup scripts and sample configurations.
526 If you cannot use one of the precompiled packages, or you want to compile tinc
527 for yourself, you can use the source. The source is distributed under
528 the GNU General Public License (GPL). Download the source from the
529 @uref{http://www.tinc-vpn.org/download/, download page}, which has
530 the checksums of these files listed; you may wish to check these with
531 md5sum before continuing.
533 Tinc comes in a convenient autoconf/automake package, which you can just
534 treat the same as any other package. Which is just untar it, type
535 `./configure' and then `make'.
536 More detailed instructions are in the file @file{INSTALL}, which is
537 included in the source distribution.
540 * Building and installing tinc::
545 @c ==================================================================
546 @node Building and installing tinc
547 @section Building and installing tinc
549 Detailed instructions on configuring the source, building tinc and installing tinc
550 can be found in the file called @file{INSTALL}.
552 @cindex binary package
553 If you happen to have a binary package for tinc for your distribution,
554 you can use the package management tools of that distribution to install tinc.
555 The documentation that comes along with your distribution will tell you how to do that.
558 * Darwin (MacOS/X) build environment::
559 * Cygwin (Windows) build environment::
560 * MinGW (Windows) build environment::
564 @c ==================================================================
565 @node Darwin (MacOS/X) build environment
566 @subsection Darwin (MacOS/X) build environment
568 In order to build tinc on Darwin, you need to install the MacOS/X Developer Tools
569 from @uref{http://developer.apple.com/tools/macosxtools.html} and
570 a recent version of Fink from @uref{http://www.finkproject.org/}.
572 After installation use fink to download and install the following packages:
573 autoconf25, automake, dlcompat, m4, openssl, zlib and lzo.
575 @c ==================================================================
576 @node Cygwin (Windows) build environment
577 @subsection Cygwin (Windows) build environment
579 If Cygwin hasn't already been installed, install it directly from
580 @uref{http://www.cygwin.com/}.
582 When tinc is compiled in a Cygwin environment, it can only be run in this environment,
583 but all programs, including those started outside the Cygwin environment, will be able to use the VPN.
584 It will also support all features.
586 @c ==================================================================
587 @node MinGW (Windows) build environment
588 @subsection MinGW (Windows) build environment
590 You will need to install the MinGW environment from @uref{http://www.mingw.org}.
592 When tinc is compiled using MinGW it runs natively under Windows,
593 it is not necessary to keep MinGW installed.
595 When detaching, tinc will install itself as a service,
596 which will be restarted automatically after reboots.
599 @c ==================================================================
601 @section System files
603 Before you can run tinc, you must make sure you have all the needed
604 files on your system.
612 @c ==================================================================
614 @subsection Device files
617 Most operating systems nowadays come with the necessary device files by default,
618 or they have a mechanism to create them on demand.
620 If you use Linux and do not have udev installed,
621 you may need to create the following device file if it does not exist:
624 mknod -m 600 /dev/net/tun c 10 200
628 @c ==================================================================
630 @subsection Other files
632 @subsubheading @file{/etc/networks}
634 You may add a line to @file{/etc/networks} so that your VPN will get a
635 symbolic name. For example:
641 @subsubheading @file{/etc/services}
644 You may add this line to @file{/etc/services}. The effect is that you
645 may supply a @samp{tinc} as a valid port number to some programs. The
646 number 655 is registered with the IANA.
651 # Ivo Timmermans <ivo@@tinc-vpn.org>
666 @c ==================================================================
668 @chapter Configuration
671 * Configuration introduction::
672 * Multiple networks::
673 * How connections work::
674 * Configuration files::
675 * Network interfaces::
676 * Example configuration::
679 @c ==================================================================
680 @node Configuration introduction
681 @section Configuration introduction
683 Before actually starting to configure tinc and editing files,
684 make sure you have read this entire section so you know what to expect.
685 Then, make it clear to yourself how you want to organize your VPN:
686 What are the nodes (computers running tinc)?
687 What IP addresses/subnets do they have?
688 What is the network mask of the entire VPN?
689 Do you need special firewall rules?
690 Do you have to set up masquerading or forwarding rules?
691 Do you want to run tinc in router mode or switch mode?
692 These questions can only be answered by yourself,
693 you will not find the answers in this documentation.
694 Make sure you have an adequate understanding of networks in general.
695 @cindex Network Administrators Guide
696 A good resource on networking is the
697 @uref{http://www.tldp.org/LDP/nag2/, Linux Network Administrators Guide}.
699 If you have everything clearly pictured in your mind,
700 proceed in the following order:
701 First, create the initial configuration files and public/private keypairs using the following command:
703 tinc -n @var{NETNAME} init @var{NAME}
705 Second, use @samp{tinc -n @var{NETNAME} add ...} to further configure tinc.
706 Finally, export your host configuration file using @samp{tinc -n @var{NETNAME} export} and send it to those
707 people or computers you want tinc to connect to.
708 They should send you their host configuration file back, which you can import using @samp{tinc -n @var{NETNAME} import}.
710 These steps are described in the subsections below.
713 @c ==================================================================
714 @node Multiple networks
715 @section Multiple networks
717 @cindex multiple networks
720 In order to allow you to run more than one tinc daemon on one computer,
721 for instance if your computer is part of more than one VPN,
722 you can assign a @var{netname} to your VPN.
723 It is not required if you only run one tinc daemon,
724 it doesn't even have to be the same on all the nodes of your VPN,
725 but it is recommended that you choose one anyway.
727 We will asume you use a netname throughout this document.
728 This means that you call tinc with the -n argument,
729 which will specify the netname.
731 The effect of this option is that tinc will set its configuration
732 root to @file{@value{sysconfdir}/tinc/@var{netname}/}, where @var{netname} is your argument to the -n option.
733 You will also notice that log messages it appears in syslog as coming from @file{tinc.@var{netname}},
734 and on Linux, unless specified otherwise, the name of the virtual network interface will be the same as the network name.
736 However, it is not strictly necessary that you call tinc with the -n
737 option. If you do not use it, the network name will just be empty, and
738 tinc will look for files in @file{@value{sysconfdir}/tinc/} instead of
739 @file{@value{sysconfdir}/tinc/@var{netname}/};
740 the configuration file will then be @file{@value{sysconfdir}/tinc/tinc.conf},
741 and the host configuration files are expected to be in @file{@value{sysconfdir}/tinc/hosts/}.
744 @c ==================================================================
745 @node How connections work
746 @section How connections work
748 When tinc starts up, it parses the command-line options and then
749 reads in the configuration file tinc.conf.
750 If it sees one or more `ConnectTo' values pointing to other tinc daemons in that file,
751 it will try to connect to those other daemons.
752 Whether this succeeds or not and whether `ConnectTo' is specified or not,
753 tinc will listen for incoming connection from other deamons.
754 If you did specify a `ConnectTo' value and the other side is not responding,
755 tinc will keep retrying.
756 This means that once started, tinc will stay running until you tell it to stop,
757 and failures to connect to other tinc daemons will not stop your tinc daemon
758 for trying again later.
759 This means you don't have to intervene if there are temporary network problems.
763 There is no real distinction between a server and a client in tinc.
764 If you wish, you can view a tinc daemon without a `ConnectTo' value as a server,
765 and one which does specify such a value as a client.
766 It does not matter if two tinc daemons have a `ConnectTo' value pointing to each other however.
768 Connections specified using `ConnectTo' are so-called meta-connections.
769 Tinc daemons exchange information about all other daemon they know about via these meta-connections.
770 After learning about all the daemons in the VPN,
771 tinc will create other connections as necessary in order to communicate with them.
772 For example, if there are three daemons named A, B and C, and A has @samp{ConnectTo = B} in its tinc.conf file,
773 and C has @samp{ConnectTo = B} in its tinc.conf file, then A will learn about C from B,
774 and will be able to exchange VPN packets with C without the need to have @samp{ConnectTo = C} in its tinc.conf file.
776 It could be that some daemons are located behind a Network Address Translation (NAT) device, or behind a firewall.
777 In the above scenario with three daemons, if A and C are behind a NAT,
778 B will automatically help A and C punch holes through their NAT,
779 in a way similar to the STUN protocol, so that A and C can still communicate with each other directly.
780 It is not always possible to do this however, and firewalls might also prevent direct communication.
781 In that case, VPN packets between A and C will be forwarded by B.
783 In effect, all nodes in the VPN will be able to talk to each other, as long as
784 their is a path of meta-connections between them, and whenever possible, two
785 nodes will communicate with each other directly.
788 @c ==================================================================
789 @node Configuration files
790 @section Configuration files
792 The actual configuration of the daemon is done in the file
793 @file{@value{sysconfdir}/tinc/@var{netname}/tinc.conf} and at least one other file in the directory
794 @file{@value{sysconfdir}/tinc/@var{netname}/hosts/}.
796 An optionnal directory @file{@value{sysconfdir}/tinc/@var{netname}/conf.d} can be added from which
797 any .conf file will be read.
799 These file consists of comments (lines started with a #) or assignments
806 The variable names are case insensitive, and any spaces, tabs, newlines
807 and carriage returns are ignored. Note: it is not required that you put
808 in the `=' sign, but doing so improves readability. If you leave it
809 out, remember to replace it with at least one space character.
811 The server configuration is complemented with host specific configuration (see
812 the next section). Although all host configuration options for the local node
813 listed in this document can also be put in
814 @file{@value{sysconfdir}/tinc/@var{netname}/tinc.conf}, it is recommended to
815 put host specific configuration options in the host configuration file, as this
816 makes it easy to exchange with other nodes.
818 You can edit the config file manually, but it is recommended that you use
819 the tinc command to change configuration variables for you.
821 In the following two subsections all valid variables are listed in alphabetical order.
822 The default value is given between parentheses,
823 other comments are between square brackets.
826 * Main configuration variables::
827 * Host configuration variables::
833 @c ==================================================================
834 @node Main configuration variables
835 @subsection Main configuration variables
838 @cindex AddressFamily
839 @item AddressFamily = <ipv4|ipv6|any> (any)
840 This option affects the address family of listening and outgoing sockets.
841 If any is selected, then depending on the operating system
842 both IPv4 and IPv6 or just IPv6 listening sockets will be created.
845 @item AutoConnect = <yes|no> (no) [experimental]
846 If set to yes, tinc will automatically set up meta connections to other nodes,
847 without requiring @var{ConnectTo} variables.
849 @cindex BindToAddress
850 @item BindToAddress = <@var{address}> [<@var{port}>]
851 This is the same as ListenAddress, however the address given with the BindToAddress option
852 will also be used for outgoing connections.
853 This is useful if your computer has more than one IPv4 or IPv6 address,
854 and you want tinc to only use a specific one for outgoing packets.
856 @cindex BindToInterface
857 @item BindToInterface = <@var{interface}> [experimental]
858 If you have more than one network interface in your computer, tinc will
859 by default listen on all of them for incoming connections. It is
860 possible to bind tinc to a single interface like eth0 or ppp0 with this
863 This option may not work on all platforms.
864 Also, on some platforms it will not actually bind to an interface,
865 but rather to the address that the interface has at the moment a socket is created.
868 @item Broadcast = <no | mst | direct> (mst) [experimental]
869 This option selects the way broadcast packets are sent to other daemons.
870 @emph{NOTE: all nodes in a VPN must use the same Broadcast mode, otherwise routing loops can form.}
874 Broadcast packets are never sent to other nodes.
877 Broadcast packets are sent and forwarded via the VPN's Minimum Spanning Tree.
878 This ensures broadcast packets reach all nodes.
881 Broadcast packets are sent directly to all nodes that can be reached directly.
882 Broadcast packets received from other nodes are never forwarded.
883 If the IndirectData option is also set, broadcast packets will only be sent to nodes which we have a meta connection to.
886 @cindex BroadcastSubnet
887 @item BroadcastSubnet = @var{address}[/@var{prefixlength}]
888 Declares a broadcast subnet.
889 Any packet with a destination address falling into such a subnet will be routed as a broadcast
890 (provided all nodes have it declared).
891 This is most useful to declare subnet broadcast addresses (e.g. 10.42.255.255),
892 otherwise tinc won't know what to do with them.
894 Note that global broadcast addresses (MAC ff:ff:ff:ff:ff:ff, IPv4 255.255.255.255),
895 as well as multicast space (IPv4 224.0.0.0/4, IPv6 ff00::/8)
896 are always considered broadcast addresses and don't need to be declared.
899 @item ConnectTo = <@var{name}>
900 Specifies which other tinc daemon to connect to on startup.
901 Multiple ConnectTo variables may be specified,
902 in which case outgoing connections to each specified tinc daemon are made.
903 The names should be known to this tinc daemon
904 (i.e., there should be a host configuration file for the name on the ConnectTo line).
906 If you don't specify a host with ConnectTo and don't enable AutoConnect,
907 tinc won't try to connect to other daemons at all,
908 and will instead just listen for incoming connections.
911 @item DecrementTTL = <yes | no> (no) [experimental]
912 When enabled, tinc will decrement the Time To Live field in IPv4 packets, or the Hop Limit field in IPv6 packets,
913 before forwarding a received packet to the virtual network device or to another node,
914 and will drop packets that have a TTL value of zero,
915 in which case it will send an ICMP Time Exceeded packet back.
917 Do not use this option if you use switch mode and want to use IPv6.
920 @item Device = <@var{device}> (@file{/dev/tap0}, @file{/dev/net/tun} or other depending on platform)
921 The virtual network device to use.
922 Tinc will automatically detect what kind of device it is.
923 Note that you can only use one device per daemon.
924 Under Windows, use @var{Interface} instead of @var{Device}.
925 Note that you can only use one device per daemon.
926 See also @ref{Device files}.
928 @cindex DeviceStandby
929 @item DeviceStandby = <yes | no> (no)
930 When disabled, tinc calls @file{tinc-up} on startup, and @file{tinc-down} on shutdown.
931 When enabled, tinc will only call @file{tinc-up} when at least one node is reachable,
932 and will call @file{tinc-down} as soon as no nodes are reachable.
933 On Windows, this also determines when the virtual network interface "cable" is "plugged".
936 @item DeviceType = <@var{type}> (platform dependent)
937 The type of the virtual network device.
938 Tinc will normally automatically select the right type of tun/tap interface, and this option should not be used.
939 However, this option can be used to select one of the special interface types, if support for them is compiled in.
944 Use a dummy interface.
945 No packets are ever read or written to a virtual network device.
946 Useful for testing, or when setting up a node that only forwards packets for other nodes.
950 Open a raw socket, and bind it to a pre-existing
951 @var{Interface} (eth0 by default).
952 All packets are read from this interface.
953 Packets received for the local node are written to the raw socket.
954 However, at least on Linux, the operating system does not process IP packets destined for the local host.
958 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}.
959 Packets are read from and written to this multicast socket.
960 This can be used to connect to UML, QEMU or KVM instances listening on the same multicast address.
961 Do NOT connect multiple tinc daemons to the same multicast address, this will very likely cause routing loops.
962 Also note that this can cause decrypted VPN packets to be sent out on a real network if misconfigured.
965 @item uml (not compiled in by default)
966 Create a UNIX socket with the filename specified by
967 @var{Device}, or @file{@value{localstatedir}/run/@var{netname}.umlsocket}
969 Tinc will wait for a User Mode Linux instance to connect to this socket.
972 @item vde (not compiled in by default)
973 Uses the libvdeplug library to connect to a Virtual Distributed Ethernet switch,
974 using the UNIX socket specified by
975 @var{Device}, or @file{@value{localstatedir}/run/vde.ctl}
979 Also, in case tinc does not seem to correctly interpret packets received from the virtual network device,
980 it can be used to change the way packets are interpreted:
983 @item tun (BSD and Linux)
985 Depending on the platform, this can either be with or without an address family header (see below).
988 @item tunnohead (BSD)
989 Set type to tun without an address family header.
990 Tinc will expect packets read from the virtual network device to start with an IP header.
991 On some platforms IPv6 packets cannot be read from or written to the device in this mode.
994 @item tunifhead (BSD)
995 Set type to tun with an address family header.
996 Tinc will expect packets read from the virtual network device
997 to start with a four byte header containing the address family,
998 followed by an IP header.
999 This mode should support both IPv4 and IPv6 packets.
1004 This is only supported on OS X version 10.6.8 and higher, but doesn't require the tuntaposx module.
1005 This mode should support both IPv4 and IPv6 packets.
1007 @item tap (BSD and Linux)
1009 Tinc will expect packets read from the virtual network device
1010 to start with an Ethernet header.
1014 @item DirectOnly = <yes|no> (no) [experimental]
1015 When this option is enabled, packets that cannot be sent directly to the destination node,
1016 but which would have to be forwarded by an intermediate node, are dropped instead.
1017 When combined with the IndirectData option,
1018 packets for nodes for which we do not have a meta connection with are also dropped.
1020 @cindex Ed25519PrivateKeyFile
1021 @item Ed25519PrivateKeyFile = <@var{path}> (@file{@value{sysconfdir}/tinc/@var{netname}/ed25519_key.priv})
1022 The file in which the private Ed25519 key of this tinc daemon resides.
1023 This is only used if ExperimentalProtocol is enabled.
1025 @cindex ExperimentalProtocol
1026 @item ExperimentalProtocol = <yes|no> (yes)
1027 When this option is enabled, the SPTPS protocol will be used when connecting to nodes that also support it.
1028 Ephemeral ECDH will be used for key exchanges,
1029 and Ed25519 will be used instead of RSA for authentication.
1030 When enabled, an Ed25519 key must have been generated before with
1031 @samp{tinc generate-ed25519-keys}.
1034 @item Forwarding = <off|internal|kernel> (internal) [experimental]
1035 This option selects the way indirect packets are forwarded.
1039 Incoming packets that are not meant for the local node,
1040 but which should be forwarded to another node, are dropped.
1043 Incoming packets that are meant for another node are forwarded by tinc internally.
1045 This is the default mode, and unless you really know you need another forwarding mode, don't change it.
1048 Incoming packets are always sent to the TUN/TAP device, even if the packets are not for the local node.
1049 This is less efficient, but allows the kernel to apply its routing and firewall rules on them,
1050 and can also help debugging.
1054 @item Hostnames = <yes|no> (no)
1055 This option selects whether IP addresses (both real and on the VPN)
1056 should be resolved. Since DNS lookups are blocking, it might affect
1057 tinc's efficiency, even stopping the daemon for a few seconds everytime
1058 it does a lookup if your DNS server is not responding.
1060 This does not affect resolving hostnames to IP addresses from the
1061 configuration file, but whether hostnames should be resolved while logging.
1064 @item Interface = <@var{interface}>
1065 Defines the name of the interface corresponding to the virtual network device.
1066 Depending on the operating system and the type of device this may or may not actually set the name of the interface.
1067 Under Windows, this variable is used to select which network interface will be used.
1068 If you specified a Device, this variable is almost always already correctly set.
1070 @cindex ListenAddress
1071 @item ListenAddress = <@var{address}> [<@var{port}>]
1072 If your computer has more than one IPv4 or IPv6 address, tinc
1073 will by default listen on all of them for incoming connections.
1074 This option can be used to restrict which addresses tinc listens on.
1075 Multiple ListenAddress variables may be specified,
1076 in which case listening sockets for each specified address are made.
1078 If no @var{port} is specified, the socket will listen on the port specified by the Port option,
1079 or to port 655 if neither is given.
1080 To only listen on a specific port but not to a specific address, use "*" for the @var{address}.
1082 @cindex LocalDiscovery
1083 @item LocalDiscovery = <yes | no> (no)
1084 When enabled, tinc will try to detect peers that are on the same local network.
1085 This will allow direct communication using LAN addresses, even if both peers are behind a NAT
1086 and they only ConnectTo a third node outside the NAT,
1087 which normally would prevent the peers from learning each other's LAN address.
1089 Currently, local discovery is implemented by sending some packets to the local address of the node during UDP discovery.
1090 This will not work with old nodes that don't transmit their local address.
1092 @cindex LocalDiscoveryAddress
1093 @item LocalDiscoveryAddress <@var{address}>
1094 If this variable is specified, local discovery packets are sent to the given @var{address}.
1097 @item Mode = <router|switch|hub> (router)
1098 This option selects the way packets are routed to other daemons.
1104 variables in the host configuration files will be used to form a routing table.
1105 Only packets of routable protocols (IPv4 and IPv6) are supported in this mode.
1107 This is the default mode, and unless you really know you need another mode, don't change it.
1111 In this mode the MAC addresses of the packets on the VPN will be used to
1112 dynamically create a routing table just like an Ethernet switch does.
1113 Unicast, multicast and broadcast packets of every protocol that runs over Ethernet are supported in this mode
1114 at the cost of frequent broadcast ARP requests and routing table updates.
1116 This mode is primarily useful if you want to bridge Ethernet segments.
1120 This mode is almost the same as the switch mode, but instead
1121 every packet will be broadcast to the other daemons
1122 while no routing table is managed.
1126 @item KeyExpire = <@var{seconds}> (3600)
1127 This option controls the time the encryption keys used to encrypt the data
1128 are valid. It is common practice to change keys at regular intervals to
1129 make it even harder for crackers, even though it is thought to be nearly
1130 impossible to crack a single key.
1133 @item MACExpire = <@var{seconds}> (600)
1134 This option controls the amount of time MAC addresses are kept before they are removed.
1135 This only has effect when Mode is set to "switch".
1137 @cindex MaxConnectionBurst
1138 @item MaxConnectionBurst = <@var{count}> (100)
1139 This option controls how many connections tinc accepts in quick succession.
1140 If there are more connections than the given number in a short time interval,
1141 tinc will reduce the number of accepted connections to only one per second,
1142 until the burst has passed.
1145 @item Name = <@var{name}> [required]
1146 This is a symbolic name for this connection.
1147 The name must consist only of alfanumeric and underscore characters (a-z, A-Z, 0-9 and _), and is case sensitive.
1149 If Name starts with a $, then the contents of the environment variable that follows will be used.
1150 In that case, invalid characters will be converted to underscores.
1151 If Name is $HOST, but no such environment variable exist,
1152 the hostname will be read using the gethostname() system call.
1154 @cindex PingInterval
1155 @item PingInterval = <@var{seconds}> (60)
1156 The number of seconds of inactivity that tinc will wait before sending a
1157 probe to the other end.
1160 @item PingTimeout = <@var{seconds}> (5)
1161 The number of seconds to wait for a response to pings or to allow meta
1162 connections to block. If the other end doesn't respond within this time,
1163 the connection is terminated, and the others will be notified of this.
1165 @cindex PriorityInheritance
1166 @item PriorityInheritance = <yes|no> (no) [experimental]
1167 When this option is enabled the value of the TOS field of tunneled IPv4 packets
1168 will be inherited by the UDP packets that are sent out.
1171 @item PrivateKey = <@var{key}> [obsolete]
1172 This is the RSA private key for tinc. However, for safety reasons it is
1173 advised to store private keys of any kind in separate files. This prevents
1174 accidental eavesdropping if you are editting the configuration file.
1176 @cindex PrivateKeyFile
1177 @item PrivateKeyFile = <@var{path}> (@file{@value{sysconfdir}/tinc/@var{netname}/rsa_key.priv})
1178 This is the full path name of the RSA private key file that was
1179 generated by @samp{tinc generate-keys}. It must be a full path, not a
1182 @cindex ProcessPriority
1183 @item ProcessPriority = <low|normal|high>
1184 When this option is used the priority of the tincd process will be adjusted.
1185 Increasing the priority may help to reduce latency and packet loss on the VPN.
1188 @item Proxy = socks4 | socks5 | http | exec @var{...} [experimental]
1189 Use a proxy when making outgoing connections.
1190 The following proxy types are currently supported:
1194 @item socks4 <@var{address}> <@var{port}> [<@var{username}>]
1195 Connects to the proxy using the SOCKS version 4 protocol.
1196 Optionally, a @var{username} can be supplied which will be passed on to the proxy server.
1199 @item socks5 <@var{address}> <@var{port}> [<@var{username}> <@var{password}>]
1200 Connect to the proxy using the SOCKS version 5 protocol.
1201 If a @var{username} and @var{password} are given, basic username/password authentication will be used,
1202 otherwise no authentication will be used.
1205 @item http <@var{address}> <@var{port}>
1206 Connects to the proxy and sends a HTTP CONNECT request.
1209 @item exec <@var{command}>
1210 Executes the given command which should set up the outgoing connection.
1211 The environment variables @env{NAME}, @env{NODE}, @env{REMOTEADDRES} and @env{REMOTEPORT} are available.
1214 @cindex ReplayWindow
1215 @item ReplayWindow = <bytes> (32)
1216 This is the size of the replay tracking window for each remote node, in bytes.
1217 The window is a bitfield which tracks 1 packet per bit, so for example
1218 the default setting of 32 will track up to 256 packets in the window. In high
1219 bandwidth scenarios, setting this to a higher value can reduce packet loss from
1220 the interaction of replay tracking with underlying real packet loss and/or
1221 reordering. Setting this to zero will disable replay tracking completely and
1222 pass all traffic, but leaves tinc vulnerable to replay-based attacks on your
1225 @cindex StrictSubnets
1226 @item StrictSubnets = <yes|no> (no) [experimental]
1227 When this option is enabled tinc will only use Subnet statements which are
1228 present in the host config files in the local
1229 @file{@value{sysconfdir}/tinc/@var{netname}/hosts/} directory.
1230 Subnets learned via connections to other nodes and which are not
1231 present in the local host config files are ignored.
1233 @cindex TunnelServer
1234 @item TunnelServer = <yes|no> (no) [experimental]
1235 When this option is enabled tinc will no longer forward information between other tinc daemons,
1236 and will only allow connections with nodes for which host config files are present in the local
1237 @file{@value{sysconfdir}/tinc/@var{netname}/hosts/} directory.
1238 Setting this options also implicitly sets StrictSubnets.
1241 @item UDPDiscovery = <yes|no> (yes)
1242 When this option is enabled tinc will try to establish UDP connectivity to nodes,
1243 using TCP while it determines if a node is reachable over UDP. If it is disabled,
1244 tinc always assumes a node is reachable over UDP.
1245 Note that tinc will never use UDP with nodes that have TCPOnly enabled.
1247 @cindex UDPDiscoveryKeepaliveInterval
1248 @item UDPDiscoveryKeepaliveInterval = <seconds> (9)
1249 The minimum amount of time between sending UDP ping datagrams to check UDP connectivity once it has been established.
1250 Note that these pings are large, since they are used to verify link MTU as well.
1252 @cindex UDPDiscoveryInterval
1253 @item UDPDiscoveryInterval = <seconds> (2)
1254 The minimum amount of time between sending UDP ping datagrams to try to establish UDP connectivity.
1256 @cindex UDPDiscoveryTimeout
1257 @item UDPDiscoveryTimeout = <seconds> (30)
1258 If tinc doesn't receive any UDP ping replies over the specified interval,
1259 it will assume UDP communication is broken and will fall back to TCP.
1261 @cindex UDPInfoInterval
1262 @item UDPInfoInterval = <seconds> (5)
1263 The minimum amount of time between sending periodic updates about UDP addresses, which are mostly useful for UDP hole punching.
1266 @item UDPRcvBuf = <bytes> (1048576)
1267 Sets the socket receive buffer size for the UDP socket, in bytes.
1268 If set to zero, the default buffer size will be used by the operating system.
1269 Note: this setting can have a significant impact on performance, especially raw throughput.
1272 @item UDPSndBuf = <bytes> (1048576)
1273 Sets the socket send buffer size for the UDP socket, in bytes.
1274 If set to zero, the default buffer size will be used by the operating system.
1275 Note: this setting can have a significant impact on performance, especially raw throughput.
1278 @item UPnP = <yes|udponly|no> (no)
1279 If this option is enabled then tinc will search for UPnP-IGD devices on the local network.
1280 It will then create and maintain port mappings for tinc's listening TCP and UDP ports.
1281 If set to "udponly", tinc will only create a mapping for its UDP (data) port, not for its TCP (metaconnection) port.
1282 Note that tinc must have been built with miniupnpc support for this feature to be available.
1283 Furthermore, be advised that enabling this can have security implications, because the miniupnpc library that
1284 tinc uses might not be well-hardened with regard to malicious UPnP replies.
1286 @cindex UPnPDiscoverWait
1287 @item UPnPDiscoverWait = <seconds> (5)
1288 The amount of time to wait for replies when probing the local network for UPnP devices.
1290 @cindex UPnPRefreshPeriod
1291 @item UPnPRefreshPeriod = <seconds> (5)
1292 How often tinc will re-add the port mapping, in case it gets reset on the UPnP device.
1293 This also controls the duration of the port mapping itself, which will be set to twice that duration.
1298 @c ==================================================================
1299 @node Host configuration variables
1300 @subsection Host configuration variables
1304 @item Address = <@var{IP address}|@var{hostname}> [<port>] [recommended]
1305 This variable is only required if you want to connect to this host. It
1306 must resolve to the external IP address where the host can be reached,
1307 not the one that is internal to the VPN.
1308 If no port is specified, the default Port is used.
1309 Multiple Address variables can be specified, in which case each address will be
1310 tried until a working connection has been established.
1313 @item Cipher = <@var{cipher}> (blowfish)
1314 The symmetric cipher algorithm used to encrypt UDP packets using the legacy protocol.
1315 Any cipher supported by OpenSSL is recognized.
1316 Furthermore, specifying "none" will turn off packet encryption.
1317 It is best to use only those ciphers which support CBC mode.
1318 This option has no effect for connections using the SPTPS protocol, which always use AES-256-CTR.
1321 @item ClampMSS = <yes|no> (yes)
1322 This option specifies whether tinc should clamp the maximum segment size (MSS)
1323 of TCP packets to the path MTU. This helps in situations where ICMP
1324 Fragmentation Needed or Packet too Big messages are dropped by firewalls.
1327 @item Compression = <@var{level}> (0)
1328 This option sets the level of compression used for UDP packets.
1329 Possible values are 0 (off), 1 (fast zlib) and any integer up to 9 (best zlib),
1330 10 (fast lzo) and 11 (best lzo).
1333 @item Digest = <@var{digest}> (sha1)
1334 The digest algorithm used to authenticate UDP packets using the legacy protocol.
1335 Any digest supported by OpenSSL is recognized.
1336 Furthermore, specifying "none" will turn off packet authentication.
1337 This option has no effect for connections using the SPTPS protocol, which always use HMAC-SHA-256.
1339 @cindex IndirectData
1340 @item IndirectData = <yes|no> (no)
1341 When set to yes, other nodes which do not already have a meta connection to you
1342 will not try to establish direct communication with you.
1343 It is best to leave this option out or set it to no.
1346 @item MACLength = <@var{bytes}> (4)
1347 The length of the message authentication code used to authenticate UDP packets using the legacy protocol.
1348 Can be anything from 0
1349 up to the length of the digest produced by the digest algorithm.
1350 This option has no effect for connections using the SPTPS protocol, which never truncate MACs.
1353 @item PMTU = <@var{mtu}> (1514)
1354 This option controls the initial path MTU to this node.
1356 @cindex PMTUDiscovery
1357 @item PMTUDiscovery = <yes|no> (yes)
1358 When this option is enabled, tinc will try to discover the path MTU to this node.
1359 After the path MTU has been discovered, it will be enforced on the VPN.
1361 @cindex MTUInfoInterval
1362 @item MTUInfoInterval = <seconds> (5)
1363 The minimum amount of time between sending periodic updates about relay path MTU. Useful for quickly determining MTU to indirect nodes.
1366 @item Port = <@var{port}> (655)
1367 This is the port this tinc daemon listens on.
1368 You can use decimal portnumbers or symbolic names (as listed in @file{/etc/services}).
1371 @item PublicKey = <@var{key}> [obsolete]
1372 This is the RSA public key for this host.
1374 @cindex PublicKeyFile
1375 @item PublicKeyFile = <@var{path}> [obsolete]
1376 This is the full path name of the RSA public key file that was generated
1377 by @samp{tinc generate-keys}. It must be a full path, not a relative
1381 From version 1.0pre4 on tinc will store the public key directly into the
1382 host configuration file in PEM format, the above two options then are not
1383 necessary. Either the PEM format is used, or exactly
1384 @strong{one of the above two options} must be specified
1385 in each host configuration file, if you want to be able to establish a
1386 connection with that host.
1389 @item Subnet = <@var{address}[/@var{prefixlength}[#@var{weight}]]>
1390 The subnet which this tinc daemon will serve.
1391 Tinc tries to look up which other daemon it should send a packet to by searching the appropiate subnet.
1392 If the packet matches a subnet,
1393 it will be sent to the daemon who has this subnet in his host configuration file.
1394 Multiple subnet lines can be specified for each daemon.
1396 Subnets can either be single MAC, IPv4 or IPv6 addresses,
1397 in which case a subnet consisting of only that single address is assumed,
1398 or they can be a IPv4 or IPv6 network address with a prefixlength.
1399 For example, IPv4 subnets must be in a form like 192.168.1.0/24,
1400 where 192.168.1.0 is the network address and 24 is the number of bits set in the netmask.
1401 Note that subnets like 192.168.1.1/24 are invalid!
1402 Read a networking HOWTO/FAQ/guide if you don't understand this.
1403 IPv6 subnets are notated like fec0:0:0:1::/64.
1404 MAC addresses are notated like 0:1a:2b:3c:4d:5e.
1406 @cindex CIDR notation
1407 Prefixlength is the number of bits set to 1 in the netmask part; for
1408 example: netmask 255.255.255.0 would become /24, 255.255.252.0 becomes
1409 /22. This conforms to standard CIDR notation as described in
1410 @uref{http://www.ietf.org/rfc/rfc1519.txt, RFC1519}
1412 A Subnet can be given a weight to indicate its priority over identical Subnets
1413 owned by different nodes. The default weight is 10. Lower values indicate
1414 higher priority. Packets will be sent to the node with the highest priority,
1415 unless that node is not reachable, in which case the node with the next highest
1416 priority will be tried, and so on.
1419 @item TCPonly = <yes|no> (no)
1420 If this variable is set to yes, then the packets are tunnelled over a
1421 TCP connection instead of a UDP connection. This is especially useful
1422 for those who want to run a tinc daemon from behind a masquerading
1423 firewall, or if UDP packet routing is disabled somehow.
1424 Setting this options also implicitly sets IndirectData.
1427 @item Weight = <weight>
1428 If this variable is set, it overrides the weight given to connections made with
1429 another host. A higher weight means a lower priority is given to this
1430 connection when broadcasting or forwarding packets.
1434 @c ==================================================================
1439 Apart from reading the server and host configuration files,
1440 tinc can also run scripts at certain moments.
1441 Below is a list of filenames of scripts and a description of when they are run.
1442 A script is only run if it exists and if it is executable.
1444 Scripts are run synchronously;
1445 this means that tinc will temporarily stop processing packets until the called script finishes executing.
1446 This guarantees that scripts will execute in the exact same order as the events that trigger them.
1447 If you need to run commands asynchronously, you have to ensure yourself that they are being run in the background.
1449 Under Windows (not Cygwin), the scripts should have the extension @file{.bat} or @file{.cmd}.
1453 @item @value{sysconfdir}/tinc/@var{netname}/tinc-up
1454 This is the most important script.
1455 If it is present it will be executed right after the tinc daemon has been
1456 started and has connected to the virtual network device.
1457 It should be used to set up the corresponding network interface,
1458 but can also be used to start other things.
1460 Under Windows you can use the Network Connections control panel instead of creating this script.
1463 @item @value{sysconfdir}/tinc/@var{netname}/tinc-down
1464 This script is started right before the tinc daemon quits.
1466 @item @value{sysconfdir}/tinc/@var{netname}/hosts/@var{host}-up
1467 This script is started when the tinc daemon with name @var{host} becomes reachable.
1469 @item @value{sysconfdir}/tinc/@var{netname}/hosts/@var{host}-down
1470 This script is started when the tinc daemon with name @var{host} becomes unreachable.
1472 @item @value{sysconfdir}/tinc/@var{netname}/host-up
1473 This script is started when any host becomes reachable.
1475 @item @value{sysconfdir}/tinc/@var{netname}/host-down
1476 This script is started when any host becomes unreachable.
1478 @item @value{sysconfdir}/tinc/@var{netname}/subnet-up
1479 This script is started when a Subnet becomes reachable.
1480 The Subnet and the node it belongs to are passed in environment variables.
1482 @item @value{sysconfdir}/tinc/@var{netname}/subnet-down
1483 This script is started when a Subnet becomes unreachable.
1485 @item @value{sysconfdir}/tinc/@var{netname}/invitation-created
1486 This script is started when a new invitation has been created.
1488 @item @value{sysconfdir}/tinc/@var{netname}/invitation-accepted
1489 This script is started when an invitation has been used.
1493 @cindex environment variables
1494 The scripts are started without command line arguments,
1495 but can make use of certain environment variables.
1496 Under UNIX like operating systems the names of environment variables must be preceded by a $ in scripts.
1497 Under Windows, in @file{.bat} or @file{.cmd} files, they have to be put between % signs.
1502 If a netname was specified, this environment variable contains it.
1506 Contains the name of this tinc daemon.
1510 Contains the name of the virtual network device that tinc uses.
1514 Contains the name of the virtual network interface that tinc uses.
1515 This should be used for commands like ifconfig.
1519 When a host becomes (un)reachable, this is set to its name.
1520 If a subnet becomes (un)reachable, this is set to the owner of that subnet.
1522 @cindex REMOTEADDRESS
1524 When a host becomes (un)reachable, this is set to its real address.
1528 When a host becomes (un)reachable,
1529 this is set to the port number it uses for communication with other tinc daemons.
1533 When a subnet becomes (un)reachable, this is set to the subnet.
1537 When a subnet becomes (un)reachable, this is set to the subnet weight.
1539 @cindex INVITATION_FILE
1540 @item INVITATION_FILE
1541 When the @file{invitation-created} script is called,
1542 this is set to the file where the invitation details will be stored.
1544 @cindex INVITATION_URL
1545 @item INVITATION_URL
1546 When the @file{invitation-created} script is called,
1547 this is set to the invitation URL that has been created.
1550 Do not forget that under UNIX operating systems,
1551 you have to make the scripts executable, using the command @samp{chmod a+x script}.
1554 @c ==================================================================
1555 @node How to configure
1556 @subsection How to configure
1558 @subsubheading Step 1. Creating initial configuration files.
1560 The initial directory structure, configuration files and public/private keypairs are created using the following command:
1563 tinc -n @var{netname} init @var{name}
1566 (You will need to run this as root, or use "sudo".)
1567 This will create the configuration directory @file{@value{sysconfdir}/tinc/@var{netname}.},
1568 and inside it will create another directory named @file{hosts/}.
1569 In the configuration directory, it will create the file @file{tinc.conf} with the following contents:
1575 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}.
1576 It will also create a host configuration file @file{hosts/@var{name}},
1577 which will contain the corresponding public RSA and Ed25519 keys.
1579 Finally, on UNIX operating systems, it will create an executable script @file{tinc-up},
1580 which will initially not do anything except warning that you should edit it.
1582 @subsubheading Step 2. Modifying the initial configuration.
1584 Unless you want to use tinc in switch mode,
1585 you should now configure which range of addresses you will use on the VPN.
1586 Let's assume you will be part of a VPN which uses the address range 192.168.0.0/16,
1587 and you yourself have a smaller portion of that range: 192.168.2.0/24.
1588 Then you should run the following command:
1591 tinc -n @var{netname} add subnet 192.168.2.0/24
1594 This will add a Subnet statement to your host configuration file.
1595 Try opening the file @file{@value{sysconfdir}/tinc/@var{netname}/hosts/@var{name}} in an editor.
1596 You should now see a file containing the public RSA and Ed25519 keys (which looks like a bunch of random characters),
1597 and the following line at the bottom:
1600 Subnet = 192.168.2.0/24
1603 If you will use more than one address range, you can add more Subnets.
1604 For example, if you also use the IPv6 subnet fec0:0:0:2::/64, you can add it as well:
1607 tinc -n @var{netname} add subnet fec0:0:0:2::/24
1610 This will add another line to the file @file{hosts/@var{name}}.
1611 If you make a mistake, you can undo it by simply using @samp{del} instead of @samp{add}.
1613 If you want other tinc daemons to create meta-connections to your daemon,
1614 you should add your public IP address or hostname to your host configuration file.
1615 For example, if your hostname is foo.example.org, run:
1618 tinc -n @var{netname} add address foo.example.org
1621 If you already know to which daemons your daemon should make meta-connections,
1622 you should configure that now as well.
1623 Suppose you want to connect to a daemon named "bar", run:
1626 tinc -n @var{netname} add connectto bar
1629 Note that you specify the Name of the other daemon here, not an IP address or hostname!
1630 When you start tinc, and it tries to make a connection to "bar",
1631 it will look for a host configuration file named @file{hosts/bar},
1632 and will read Address statements and public keys from that file.
1634 @subsubheading Step 2. Exchanging configuration files.
1636 If your daemon has a ConnectTo = bar statement in its @file{tinc.conf} file,
1637 or if bar has a ConnectTo your daemon, then you both need each other's host configuration files.
1638 You should send @file{hosts/@var{name}} to bar, and bar should send you his file which you should move to @file{hosts/bar}.
1639 If you are on a UNIX platform, you can easily send an email containing the necessary information using the following command
1640 (assuming the owner of bar has the email address bar@@example.org):
1643 tinc -n @var{netname} export | mail -s "My config file" bar@@example.org
1646 If the owner of bar does the same to send his host configuration file to you,
1647 you can probably pipe his email through the following command,
1648 or you can just start this command in a terminal and copy&paste the email:
1651 tinc -n @var{netname} import
1654 If you are the owner of bar yourself, and you have SSH access to that computer,
1655 you can also swap the host configuration files using the following command:
1658 tinc -n @var{netname} export \
1659 | ssh bar.example.org tinc -n @var{netname} exchange \
1660 | tinc -n @var{netname} import
1663 You should repeat this for all nodes you ConnectTo, or which ConnectTo you.
1664 However, remember that you do not need to ConnectTo all nodes in the VPN;
1665 it is only necessary to create one or a few meta-connections,
1666 after the connections are made tinc will learn about all the other nodes in the VPN,
1667 and will automatically make other connections as necessary.
1670 @c ==================================================================
1671 @node Network interfaces
1672 @section Network interfaces
1674 Before tinc can start transmitting data over the tunnel, it must
1675 set up the virtual network interface.
1677 First, decide which IP addresses you want to have associated with these
1678 devices, and what network mask they must have.
1680 Tinc will open a virtual network device (@file{/dev/tun}, @file{/dev/tap0} or similar),
1681 which will also create a network interface called something like @samp{tun0}, @samp{tap0}.
1682 If you are using the Linux tun/tap driver, the network interface will by default have the same name as the @var{netname}.
1683 Under Windows you can change the name of the network interface from the Network Connections control panel.
1686 You can configure the network interface by putting ordinary ifconfig, route, and other commands
1687 to a script named @file{@value{sysconfdir}/tinc/@var{netname}/tinc-up}.
1688 When tinc starts, this script will be executed. When tinc exits, it will execute the script named
1689 @file{@value{sysconfdir}/tinc/@var{netname}/tinc-down}, but normally you don't need to create that script.
1690 You can manually open the script in an editor, or use the following command:
1693 tinc -n @var{netname} edit tinc-up
1696 An example @file{tinc-up} script, that would be appropriate for the scenario in the previous section, is:
1700 ifconfig $INTERFACE 192.168.2.1 netmask 255.255.0.0
1701 ip addr add fec0:0:0:2::/48 dev $INTERFACE
1704 The first command gives the interface an IPv4 address and a netmask.
1705 The kernel will also automatically add an IPv4 route to this interface, so normally you don't need
1706 to add route commands to the @file{tinc-up} script.
1707 The kernel will also bring the interface up after this command.
1709 The netmask is the mask of the @emph{entire} VPN network, not just your
1711 The second command gives the interface an IPv6 address and netmask,
1712 which will also automatically add an IPv6 route.
1713 If you only want to use "ip addr" commands on Linux, don't forget that it doesn't bring the interface up, unlike ifconfig,
1714 so you need to add @samp{ip link set $INTERFACE up} in that case.
1716 The exact syntax of the ifconfig and route commands differs from platform to platform.
1717 You can look up the commands for setting addresses and adding routes in @ref{Platform specific information},
1718 but it is best to consult the manpages of those utilities on your platform.
1721 @c ==================================================================
1722 @node Example configuration
1723 @section Example configuration
1727 Imagine the following situation. Branch A of our example `company' wants to connect
1728 three branch offices in B, C and D using the Internet. All four offices
1729 have a 24/7 connection to the Internet.
1731 A is going to serve as the center of the network. B and C will connect
1732 to A, and D will connect to C. Each office will be assigned their own IP
1736 A: net 10.1.0.0 mask 255.255.0.0 gateway 10.1.54.1 internet IP 1.2.3.4
1737 B: net 10.2.0.0 mask 255.255.0.0 gateway 10.2.1.12 internet IP 2.3.4.5
1738 C: net 10.3.0.0 mask 255.255.0.0 gateway 10.3.69.254 internet IP 3.4.5.6
1739 D: net 10.4.0.0 mask 255.255.0.0 gateway 10.4.3.32 internet IP 4.5.6.7
1742 Here, ``gateway'' is the VPN IP address of the machine that is running the
1743 tincd, and ``internet IP'' is the IP address of the firewall, which does not
1744 need to run tincd, but it must do a port forwarding of TCP and UDP on port
1745 655 (unless otherwise configured).
1747 In this example, it is assumed that eth0 is the interface that points to
1748 the inner (physical) LAN of the office, although this could also be the
1749 same as the interface that leads to the Internet. The configuration of
1750 the real interface is also shown as a comment, to give you an idea of
1751 how these example host is set up. All branches use the netname `company'
1752 for this particular VPN.
1754 Each branch is set up using the @samp{tinc init} and @samp{tinc config} commands,
1755 here we just show the end results:
1757 @subsubheading For Branch A
1759 @emph{BranchA} would be configured like this:
1761 In @file{@value{sysconfdir}/tinc/company/tinc-up}:
1766 # Real interface of internal network:
1767 # ifconfig eth0 10.1.54.1 netmask 255.255.0.0
1769 ifconfig $INTERFACE 10.1.54.1 netmask 255.0.0.0
1772 and in @file{@value{sysconfdir}/tinc/company/tinc.conf}:
1778 On all hosts, @file{@value{sysconfdir}/tinc/company/hosts/BranchA} contains:
1781 Subnet = 10.1.0.0/16
1784 -----BEGIN RSA PUBLIC KEY-----
1786 -----END RSA PUBLIC KEY-----
1789 Note that the IP addresses of eth0 and the VPN interface are the same.
1790 This is quite possible, if you make sure that the netmasks of the interfaces are different.
1791 It is in fact recommended to give both real internal network interfaces and VPN interfaces the same IP address,
1792 since that will make things a lot easier to remember and set up.
1795 @subsubheading For Branch B
1797 In @file{@value{sysconfdir}/tinc/company/tinc-up}:
1802 # Real interface of internal network:
1803 # ifconfig eth0 10.2.43.8 netmask 255.255.0.0
1805 ifconfig $INTERFACE 10.2.1.12 netmask 255.0.0.0
1808 and in @file{@value{sysconfdir}/tinc/company/tinc.conf}:
1815 Note here that the internal address (on eth0) doesn't have to be the
1816 same as on the VPN interface. Also, ConnectTo is given so that this node will
1817 always try to connect to BranchA.
1819 On all hosts, in @file{@value{sysconfdir}/tinc/company/hosts/BranchB}:
1822 Subnet = 10.2.0.0/16
1825 -----BEGIN RSA PUBLIC KEY-----
1827 -----END RSA PUBLIC KEY-----
1831 @subsubheading For Branch C
1833 In @file{@value{sysconfdir}/tinc/company/tinc-up}:
1838 # Real interface of internal network:
1839 # ifconfig eth0 10.3.69.254 netmask 255.255.0.0
1841 ifconfig $INTERFACE 10.3.69.254 netmask 255.0.0.0
1844 and in @file{@value{sysconfdir}/tinc/company/tinc.conf}:
1851 C already has another daemon that runs on port 655, so they have to
1852 reserve another port for tinc. It knows the portnumber it has to listen on
1853 from it's own host configuration file.
1855 On all hosts, in @file{@value{sysconfdir}/tinc/company/hosts/BranchC}:
1859 Subnet = 10.3.0.0/16
1862 -----BEGIN RSA PUBLIC KEY-----
1864 -----END RSA PUBLIC KEY-----
1868 @subsubheading For Branch D
1870 In @file{@value{sysconfdir}/tinc/company/tinc-up}:
1875 # Real interface of internal network:
1876 # ifconfig eth0 10.4.3.32 netmask 255.255.0.0
1878 ifconfig $INTERFACE 10.4.3.32 netmask 255.0.0.0
1881 and in @file{@value{sysconfdir}/tinc/company/tinc.conf}:
1888 D will be connecting to C, which has a tincd running for this network on
1889 port 2000. It knows the port number from the host configuration file.
1891 On all hosts, in @file{@value{sysconfdir}/tinc/company/hosts/BranchD}:
1894 Subnet = 10.4.0.0/16
1897 -----BEGIN RSA PUBLIC KEY-----
1899 -----END RSA PUBLIC KEY-----
1902 @subsubheading Key files
1904 A, B, C and D all have their own public/private keypairs:
1906 The private RSA key is stored in @file{@value{sysconfdir}/tinc/company/rsa_key.priv},
1907 the private Ed25519 key is stored in @file{@value{sysconfdir}/tinc/company/ed25519_key.priv},
1908 and the public RSA and Ed25519 keys are put into the host configuration file in the @file{@value{sysconfdir}/tinc/company/hosts/} directory.
1910 @subsubheading Starting
1912 After each branch has finished configuration and they have distributed
1913 the host configuration files amongst them, they can start their tinc daemons.
1914 They don't necessarily have to wait for the other branches to have started
1915 their daemons, tinc will try connecting until they are available.
1918 @c ==================================================================
1920 @chapter Running tinc
1922 If everything else is done, you can start tinc by typing the following command:
1925 tinc -n @var{netname} start
1929 Tinc will detach from the terminal and continue to run in the background like a good daemon.
1930 If there are any problems however you can try to increase the debug level
1931 and look in the syslog to find out what the problems are.
1937 * Solving problems::
1939 * Sending bug reports::
1943 @c ==================================================================
1944 @node Runtime options
1945 @section Runtime options
1947 Besides the settings in the configuration file, tinc also accepts some
1948 command line options.
1950 @cindex command line
1951 @cindex runtime options
1955 @item -c, --config=@var{path}
1956 Read configuration options from the directory @var{path}. The default is
1957 @file{@value{sysconfdir}/tinc/@var{netname}/}.
1959 @item -D, --no-detach
1960 Don't fork and detach.
1961 This will also disable the automatic restart mechanism for fatal errors.
1964 @item -d, --debug=@var{level}
1965 Set debug level to @var{level}. The higher the debug level, the more gets
1966 logged. Everything goes via syslog.
1968 @item -n, --net=@var{netname}
1969 Use configuration for net @var{netname}.
1970 This will let tinc read all configuration files from
1971 @file{@value{sysconfdir}/tinc/@var{netname}/}.
1972 Specifying . for @var{netname} is the same as not specifying any @var{netname}.
1973 @xref{Multiple networks}.
1975 @item --pidfile=@var{filename}
1976 Store a cookie in @var{filename} which allows tinc to authenticate.
1977 If unspecified, the default is
1978 @file{@value{localstatedir}/run/tinc.@var{netname}.pid}.
1980 @item -o, --option=[@var{HOST}.]@var{KEY}=@var{VALUE}
1981 Without specifying a @var{HOST}, this will set server configuration variable @var{KEY} to @var{VALUE}.
1982 If specified as @var{HOST}.@var{KEY}=@var{VALUE},
1983 this will set the host configuration variable @var{KEY} of the host named @var{HOST} to @var{VALUE}.
1984 This option can be used more than once to specify multiple configuration variables.
1987 Lock tinc into main memory.
1988 This will prevent sensitive data like shared private keys to be written to the system swap files/partitions.
1990 This option is not supported on all platforms.
1992 @item --logfile[=@var{file}]
1993 Write log entries to a file instead of to the system logging facility.
1994 If @var{file} is omitted, the default is @file{@value{localstatedir}/log/tinc.@var{netname}.log}.
1996 @item --bypass-security
1997 Disables encryption and authentication.
1998 Only useful for debugging.
2001 Change process root directory to the directory where the config file is
2002 located (@file{@value{sysconfdir}/tinc/@var{netname}/} as determined by
2003 -n/--net option or as given by -c/--config option), for added security.
2004 The chroot is performed after all the initialization is done, after
2005 writing pid files and opening network sockets.
2007 Note that this option alone does not do any good without -U/--user, below.
2009 Note also that tinc can't run scripts anymore (such as tinc-down or host-up),
2010 unless it's setup to be runnable inside chroot environment.
2012 This option is not supported on all platforms.
2013 @item -U, --user=@var{user}
2014 Switch to the given @var{user} after initialization, at the same time as
2015 chroot is performed (see --chroot above). With this option tinc drops
2016 privileges, for added security.
2018 This option is not supported on all platforms.
2021 Display a short reminder of these runtime options and terminate.
2024 Output version information and exit.
2028 @c ==================================================================
2033 You can also send the following signals to a running tincd process:
2039 Forces tinc to try to connect to all uplinks immediately.
2040 Usually tinc attempts to do this itself,
2041 but increases the time it waits between the attempts each time it failed,
2042 and if tinc didn't succeed to connect to an uplink the first time after it started,
2043 it defaults to the maximum time of 15 minutes.
2046 Partially rereads configuration files.
2047 Connections to hosts whose host config file are removed are closed.
2048 New outgoing connections specified in @file{tinc.conf} will be made.
2049 If the --logfile option is used, this will also close and reopen the log file,
2050 useful when log rotation is used.
2054 @c ==================================================================
2056 @section Debug levels
2058 @cindex debug levels
2059 The tinc daemon can send a lot of messages to the syslog.
2060 The higher the debug level, the more messages it will log.
2061 Each level inherits all messages of the previous level:
2067 This will log a message indicating tinc has started along with a version number.
2068 It will also log any serious error.
2071 This will log all connections that are made with other tinc daemons.
2074 This will log status and error messages from scripts and other tinc daemons.
2077 This will log all requests that are exchanged with other tinc daemons. These include
2078 authentication, key exchange and connection list updates.
2081 This will log a copy of everything received on the meta socket.
2084 This will log all network traffic over the virtual private network.
2088 @c ==================================================================
2089 @node Solving problems
2090 @section Solving problems
2092 If tinc starts without problems, but if the VPN doesn't work, you will have to find the cause of the problem.
2093 The first thing to do is to start tinc with a high debug level in the foreground,
2094 so you can directly see everything tinc logs:
2097 tincd -n @var{netname} -d5 -D
2100 If tinc does not log any error messages, then you might want to check the following things:
2103 @item @file{tinc-up} script
2104 Does this script contain the right commands?
2105 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.
2108 Does the Subnet (or Subnets) in the host configuration file of this host match the portion of the VPN that belongs to this host?
2110 @item Firewalls and NATs
2111 Do you have a firewall or a NAT device (a masquerading firewall or perhaps an ADSL router that performs masquerading)?
2112 If so, check that it allows TCP and UDP traffic on port 655.
2113 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.
2114 You can add @samp{TCPOnly = yes} to your host config file to force tinc to only use a single TCP connection,
2115 this works through most firewalls and NATs.
2120 @c ==================================================================
2121 @node Error messages
2122 @section Error messages
2124 What follows is a list of the most common error messages you might find in the logs.
2125 Some of them will only be visible if the debug level is high enough.
2128 @item Could not open /dev/tap0: No such device
2131 @item You forgot to `modprobe netlink_dev' or `modprobe ethertap'.
2132 @item You forgot to compile `Netlink device emulation' in the kernel.
2135 @item Can't write to /dev/net/tun: No such device
2138 @item You forgot to `modprobe tun'.
2139 @item You forgot to compile `Universal TUN/TAP driver' in the kernel.
2140 @item The tun device is located somewhere else in @file{/dev/}.
2143 @item Network address and prefix length do not match!
2146 @item The Subnet field must contain a @emph{network} address, trailing bits should be 0.
2147 @item If you only want to use one IP address, set the netmask to /32.
2150 @item Error reading RSA key file `rsa_key.priv': No such file or directory
2153 @item You forgot to create a public/private keypair.
2154 @item Specify the complete pathname to the private key file with the @samp{PrivateKeyFile} option.
2157 @item Warning: insecure file permissions for RSA private key file `rsa_key.priv'!
2160 @item The private key file is readable by users other than root.
2161 Use chmod to correct the file permissions.
2164 @item Creating metasocket failed: Address family not supported
2167 @item By default tinc tries to create both IPv4 and IPv6 sockets.
2168 On some platforms this might not be implemented.
2169 If the logs show @samp{Ready} later on, then at least one metasocket was created,
2170 and you can ignore this message.
2171 You can add @samp{AddressFamily = ipv4} to @file{tinc.conf} to prevent this from happening.
2174 @item Cannot route packet: unknown IPv4 destination 1.2.3.4
2177 @item You try to send traffic to a host on the VPN for which no Subnet is known.
2178 @item If it is a broadcast address (ending in .255), it probably is a samba server or a Windows host sending broadcast packets.
2182 @item Cannot route packet: ARP request for unknown address 1.2.3.4
2185 @item You try to send traffic to a host on the VPN for which no Subnet is known.
2188 @item Packet with destination 1.2.3.4 is looping back to us!
2191 @item Something is not configured right. Packets are being sent out to the
2192 virtual network device, but according to the Subnet directives in your host configuration
2193 file, those packets should go to your own host. Most common mistake is that
2194 you have a Subnet line in your host configuration file with a prefix length which is
2195 just as large as the prefix of the virtual network interface. The latter should in almost all
2196 cases be larger. Rethink your configuration.
2197 Note that you will only see this message if you specified a debug
2198 level of 5 or higher!
2199 @item Chances are that a @samp{Subnet = ...} line in the host configuration file of this tinc daemon is wrong.
2200 Change it to a subnet that is accepted locally by another interface,
2201 or if that is not the case, try changing the prefix length into /32.
2204 @item Node foo (1.2.3.4) is not reachable
2207 @item Node foo does not have a connection anymore, its tinc daemon is not running or its connection to the Internet is broken.
2210 @item Received UDP packet from unknown source 1.2.3.4 (port 12345)
2213 @item If you see this only sporadically, it is harmless and caused by a node sending packets using an old key.
2214 @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.
2215 You can add @samp{TCPOnly = yes} to host configuration files to force all VPN traffic to go over a TCP connection.
2218 @item Got bad/bogus/unauthorized REQUEST from foo (1.2.3.4 port 12345)
2221 @item Node foo does not have the right public/private keypair.
2222 Generate new keypairs and distribute them again.
2223 @item An attacker tries to gain access to your VPN.
2224 @item A network error caused corruption of metadata sent from foo.
2229 @c ==================================================================
2230 @node Sending bug reports
2231 @section Sending bug reports
2233 If you really can't find the cause of a problem, or if you suspect tinc is not working right,
2234 you can send us a bugreport, see @ref{Contact information}.
2235 Be sure to include the following information in your bugreport:
2238 @item A clear description of what you are trying to achieve and what the problem is.
2239 @item What platform (operating system, version, hardware architecture) and which version of tinc you use.
2240 @item If compiling tinc fails, a copy of @file{config.log} and the error messages you get.
2241 @item Otherwise, a copy of @file{tinc.conf}, @file{tinc-up} and all files in the @file{hosts/} directory.
2242 @item The output of the commands @samp{ifconfig -a} and @samp{route -n} (or @samp{netstat -rn} if that doesn't work).
2243 @item The output of any command that fails to work as it should (like ping or traceroute).
2246 @c ==================================================================
2247 @node Controlling tinc
2248 @chapter Controlling tinc
2250 @cindex command line interface
2251 You can start, stop, control and inspect a running tincd through the tinc
2252 command. A quick example:
2255 tinc -n @var{netname} reload
2259 If tinc is started without a command, it will act as a shell; it will display a
2260 prompt, and commands can be entered on the prompt. If tinc is compiled with
2261 libreadline, history and command completion are available on the prompt. One
2262 can also pipe a script containing commands through tinc. In that case, lines
2263 starting with a # symbol will be ignored.
2266 * tinc runtime options::
2267 * tinc environment variables::
2274 @c ==================================================================
2275 @node tinc runtime options
2276 @section tinc runtime options
2280 @item -c, --config=@var{path}
2281 Read configuration options from the directory @var{path}. The default is
2282 @file{@value{sysconfdir}/tinc/@var{netname}/}.
2284 @item -n, --net=@var{netname}
2285 Use configuration for net @var{netname}. @xref{Multiple networks}.
2287 @item --pidfile=@var{filename}
2288 Use the cookie from @var{filename} to authenticate with a running tinc daemon.
2289 If unspecified, the default is
2290 @file{@value{localstatedir}/run/tinc.@var{netname}.pid}.
2293 Force some commands to work despite warnings.
2296 Display a short reminder of runtime options and commands, then terminate.
2299 Output version information and exit.
2303 @c ==================================================================
2304 @node tinc environment variables
2305 @section tinc environment variables
2310 If no netname is specified on the command line with the @option{-n} option,
2311 the value of this environment variable is used.
2314 @c ==================================================================
2316 @section tinc commands
2322 @item init [@var{name}]
2323 Create initial configuration files and RSA and Ed25519 keypairs with default length.
2324 If no @var{name} for this node is given, it will be asked for.
2327 @item get @var{variable}
2328 Print the current value of configuration variable @var{variable}.
2329 If more than one variable with the same name exists,
2330 the value of each of them will be printed on a separate line.
2333 @item set @var{variable} @var{value}
2334 Set configuration variable @var{variable} to the given @var{value}.
2335 All previously existing configuration variables with the same name are removed.
2336 To set a variable for a specific host, use the notation @var{host}.@var{variable}.
2339 @item add @var{variable} @var{value}
2340 As above, but without removing any previously existing configuration variables.
2341 If the variable already exists with the given value, nothing happens.
2344 @item del @var{variable} [@var{value}]
2345 Remove configuration variables with the same name and @var{value}.
2346 If no @var{value} is given, all configuration variables with the same name will be removed.
2349 @item edit @var{filename}
2350 Start an editor for the given configuration file.
2351 You do not need to specify the full path to the file.
2355 Export the host configuration file of the local node to standard output.
2359 Export all host configuration files to standard output.
2363 Import host configuration file(s) generated by the tinc export command from standard input.
2364 Already existing host configuration files are not overwritten unless the option --force is used.
2368 The same as export followed by import.
2370 @cindex exchange-all
2372 The same as export-all followed by import.
2375 @item invite @var{name}
2376 Prepares an invitation for a new node with the given @var{name},
2377 and prints a short invitation URL that can be used with the join command.
2380 @item join [@var{URL}]
2381 Join an existing VPN using an invitation URL created using the invite command.
2382 If no @var{URL} is given, it will be read from standard input.
2385 @item start [tincd options]
2386 Start @samp{tincd}, optionally with the given extra options.
2393 @item restart [tincd options]
2394 Restart @samp{tincd}, optionally with the given extra options.
2398 Partially rereads configuration files. Connections to hosts whose host
2399 config files are removed are closed. New outgoing connections specified
2400 in @file{tinc.conf} will be made.
2404 Shows the PID of the currently running @samp{tincd}.
2406 @cindex generate-keys
2407 @item generate-keys [@var{bits}]
2408 Generate both RSA and Ed25519 keypairs (see below) and exit.
2409 tinc will ask where you want to store the files, but will default to the
2410 configuration directory (you can use the -c or -n option).
2412 @cindex generate-ed25519-keys
2413 @item generate-ed25519-keys
2414 Generate public/private Ed25519 keypair and exit.
2416 @cindex generate-rsa-keys
2417 @item generate-rsa-keys [@var{bits}]
2418 Generate public/private RSA keypair and exit. If @var{bits} is omitted, the
2419 default length will be 2048 bits. When saving keys to existing files, tinc
2420 will not delete the old keys; you have to remove them manually.
2423 @item dump [reachable] nodes
2424 Dump a list of all known nodes in the VPN.
2425 If the reachable keyword is used, only lists reachable nodes.
2428 Dump a list of all known connections in the VPN.
2431 Dump a list of all known subnets in the VPN.
2433 @item dump connections
2434 Dump a list of all meta connections with ourself.
2437 @item dump graph | digraph
2438 Dump a graph of the VPN in dotty format.
2439 Nodes are colored according to their reachability:
2440 red nodes are unreachable, orange nodes are indirectly reachable, green nodes are directly reachable.
2441 Black nodes are either directly or indirectly reachable, but direct reachability has not been tried yet.
2443 @item dump invitations
2444 Dump a list of outstanding invitations.
2445 The filename of the invitation, as well as the name of the node that is being invited is shown for each invitation.
2448 @item info @var{node} | @var{subnet} | @var{address}
2449 Show information about a particular @var{node}, @var{subnet} or @var{address}.
2450 If an @var{address} is given, any matching subnet will be shown.
2454 Purges all information remembered about unreachable nodes.
2457 @item debug @var{level}
2458 Sets debug level to @var{level}.
2461 @item log [@var{level}]
2462 Capture log messages from a running tinc daemon.
2463 An optional debug level can be given that will be applied only for log messages sent to tinc.
2467 Forces tinc to try to connect to all uplinks immediately.
2468 Usually tinc attempts to do this itself,
2469 but increases the time it waits between the attempts each time it failed,
2470 and if tinc didn't succeed to connect to an uplink the first time after it started,
2471 it defaults to the maximum time of 15 minutes.
2474 @item disconnect @var{node}
2475 Closes the meta connection with the given @var{node}.
2479 If tinc is compiled with libcurses support, this will display live traffic statistics for all the known nodes,
2480 similar to the UNIX top command.
2481 See below for more information.
2485 Dump VPN traffic going through the local tinc node in pcap-savefile format to standard output,
2486 from where it can be redirected to a file or piped through a program that can parse it directly,
2490 @item network [@var{netname}]
2491 If @var{netname} is given, switch to that network.
2492 Otherwise, display a list of all networks for which configuration files exist.
2496 This will check the configuration files for possible problems,
2497 such as unsafe file permissions, missing executable bit on script,
2498 unknown and obsolete configuration variables, wrong public and/or private keys, and so on.
2500 When problems are found, this will be printed on a line with WARNING or ERROR in front of it.
2501 Most problems must be corrected by the user itself, however in some cases (like file permissions and missing public keys),
2502 tinc will ask if it should fix the problem.
2505 @item sign [@var{filename}]
2506 Sign a file with the local node's private key.
2507 If no @var{filename} is given, the file is read from standard input.
2508 The signed file is written to standard output.
2511 @item verify @var{name} [@var{filename}]
2513 Check the signature of a file against a node's public key.
2514 The @var{name} of the node must be given,
2515 or can be "." to check against the local node's public key,
2516 or "*" to allow a signature from any node whose public key is known.
2517 If no @var{filename} is given, the file is read from standard input.
2518 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.
2519 If the verification failed, nothing will be written to standard output, and the exit code will be non-zero.
2523 @c ==================================================================
2525 @section tinc examples
2527 Examples of some commands:
2530 tinc -n vpn dump graph | circo -Txlib
2531 tinc -n vpn pcap | tcpdump -r -
2535 Examples of changing the configuration using tinc:
2538 tinc -n vpn init foo
2539 tinc -n vpn add Subnet 192.168.1.0/24
2540 tinc -n vpn add bar.Address bar.example.com
2541 tinc -n vpn add ConnectTo bar
2542 tinc -n vpn export | gpg --clearsign | mail -s "My config" vpnmaster@@example.com
2545 @c ==================================================================
2550 The top command connects to a running tinc daemon and repeatedly queries its per-node traffic counters.
2551 It displays a list of all the known nodes in the left-most column,
2552 and the amount of bytes and packets read from and sent to each node in the other columns.
2553 By default, the information is updated every second.
2554 The behaviour of the top command can be changed using the following keys:
2559 Change the interval between updates.
2560 After pressing the @key{s} key, enter the desired interval in seconds, followed by enter.
2561 Fractional seconds are honored.
2562 Intervals lower than 0.1 seconds are not allowed.
2565 Toggle between displaying current traffic rates (in packets and bytes per second)
2566 and cummulative traffic (total packets and bytes since the tinc daemon started).
2569 Sort the list of nodes by name.
2572 Sort the list of nodes by incoming amount of bytes.
2575 Sort the list of nodes by incoming amount of packets.
2578 Sort the list of nodes by outgoing amount of bytes.
2581 Sort the list of nodes by outgoing amount of packets.
2584 Sort the list of nodes by sum of incoming and outgoing amount of bytes.
2587 Sort the list of nodes by sum of incoming and outgoing amount of packets.
2590 Show amount of traffic in bytes.
2593 Show amount of traffic in kilobytes.
2596 Show amount of traffic in megabytes.
2599 Show amount of traffic in gigabytes.
2607 @c ==================================================================
2608 @node Technical information
2609 @chapter Technical information
2614 * The meta-protocol::
2619 @c ==================================================================
2620 @node The connection
2621 @section The connection
2624 Tinc is a daemon that takes VPN data and transmit that to another host
2625 computer over the existing Internet infrastructure.
2629 * The meta-connection::
2633 @c ==================================================================
2634 @node The UDP tunnel
2635 @subsection The UDP tunnel
2637 @cindex virtual network device
2639 The data itself is read from a character device file, the so-called
2640 @emph{virtual network device}. This device is associated with a network
2641 interface. Any data sent to this interface can be read from the device,
2642 and any data written to the device gets sent from the interface.
2643 There are two possible types of virtual network devices:
2644 `tun' style, which are point-to-point devices which can only handle IPv4 and/or IPv6 packets,
2645 and `tap' style, which are Ethernet devices and handle complete Ethernet frames.
2647 So when tinc reads an Ethernet frame from the device, it determines its
2648 type. When tinc is in it's default routing mode, it can handle IPv4 and IPv6
2649 packets. Depending on the Subnet lines, it will send the packets off to their destination IP address.
2650 In the `switch' and `hub' mode, tinc will use broadcasts and MAC address discovery
2651 to deduce the destination of the packets.
2652 Since the latter modes only depend on the link layer information,
2653 any protocol that runs over Ethernet is supported (for instance IPX and Appletalk).
2654 However, only `tap' style devices provide this information.
2656 After the destination has been determined,
2657 the packet will be compressed (optionally),
2658 a sequence number will be added to the packet,
2659 the packet will then be encrypted
2660 and a message authentication code will be appended.
2662 @cindex encapsulating
2664 When that is done, time has come to actually transport the
2665 packet to the destination computer. We do this by sending the packet
2666 over an UDP connection to the destination host. This is called
2667 @emph{encapsulating}, the VPN packet (though now encrypted) is
2668 encapsulated in another IP datagram.
2670 When the destination receives this packet, the same thing happens, only
2671 in reverse. So it checks the message authentication code, decrypts the contents of the UDP datagram,
2672 checks the sequence number
2673 and writes the decrypted information to its own virtual network device.
2675 If the virtual network device is a `tun' device (a point-to-point tunnel),
2676 there is no problem for the kernel to accept a packet.
2677 However, if it is a `tap' device (this is the only available type on FreeBSD),
2678 the destination MAC address must match that of the virtual network interface.
2679 If tinc is in it's default routing mode, ARP does not work, so the correct destination MAC
2680 can not be known by the sending host.
2681 Tinc solves this by letting the receiving end detect the MAC address of its own virtual network interface
2682 and overwriting the destination MAC address of the received packet.
2684 In switch or hub modes ARP does work so the sender already knows the correct destination MAC address.
2685 In those modes every interface should have a unique MAC address, so make sure they are not the same.
2686 Because switch and hub modes rely on MAC addresses to function correctly,
2687 these modes cannot be used on the following operating systems which don't have a `tap' style virtual network device:
2688 OpenBSD, NetBSD, Darwin and Solaris.
2691 @c ==================================================================
2692 @node The meta-connection
2693 @subsection The meta-connection
2695 Having only a UDP connection available is not enough. Though suitable
2696 for transmitting data, we want to be able to reliably send other
2697 information, such as routing and session key information to somebody.
2700 TCP is a better alternative, because it already contains protection
2701 against information being lost, unlike UDP.
2703 So we establish two connections. One for the encrypted VPN data, and one
2704 for other information, the meta-data. Hence, we call the second
2705 connection the meta-connection. We can now be sure that the
2706 meta-information doesn't get lost on the way to another computer.
2708 @cindex data-protocol
2709 @cindex meta-protocol
2710 Like with any communication, we must have a protocol, so that everybody
2711 knows what everything stands for, and how she should react. Because we
2712 have two connections, we also have two protocols. The protocol used for
2713 the UDP data is the ``data-protocol,'' the other one is the
2716 The reason we don't use TCP for both protocols is that UDP is much
2717 better for encapsulation, even while it is less reliable. The real
2718 problem is that when TCP would be used to encapsulate a TCP stream
2719 that's on the private network, for every packet sent there would be
2720 three ACKs sent instead of just one. Furthermore, if there would be
2721 a timeout, both TCP streams would sense the timeout, and both would
2722 start re-sending packets.
2725 @c ==================================================================
2726 @node The meta-protocol
2727 @section The meta-protocol
2729 The meta protocol is used to tie all tinc daemons together, and
2730 exchange information about which tinc daemon serves which virtual
2733 The meta protocol consists of requests that can be sent to the other
2734 side. Each request has a unique number and several parameters. All
2735 requests are represented in the standard ASCII character set. It is
2736 possible to use tools such as telnet or netcat to connect to a tinc
2737 daemon started with the --bypass-security option
2738 and to read and write requests by hand, provided that one
2739 understands the numeric codes sent.
2741 The authentication scheme is described in @ref{Security}. After a
2742 successful authentication, the server and the client will exchange all the
2743 information about other tinc daemons and subnets they know of, so that both
2744 sides (and all the other tinc daemons behind them) have their information
2751 ------------------------------------------------------------------
2752 ADD_EDGE node1 node2 21.32.43.54 655 222 0
2753 | | | | | +-> options
2754 | | | | +----> weight
2755 | | | +--------> UDP port of node2
2756 | | +----------------> real address of node2
2757 | +-------------------------> name of destination node
2758 +-------------------------------> name of source node
2760 ADD_SUBNET node 192.168.1.0/24
2761 | | +--> prefixlength
2762 | +--------> network address
2763 +------------------> owner of this subnet
2764 ------------------------------------------------------------------
2767 The ADD_EDGE messages are to inform other tinc daemons that a connection between
2768 two nodes exist. The address of the destination node is available so that
2769 VPN packets can be sent directly to that node.
2771 The ADD_SUBNET messages inform other tinc daemons that certain subnets belong
2772 to certain nodes. tinc will use it to determine to which node a VPN packet has
2779 ------------------------------------------------------------------
2780 DEL_EDGE node1 node2
2781 | +----> name of destination node
2782 +----------> name of source node
2784 DEL_SUBNET node 192.168.1.0/24
2785 | | +--> prefixlength
2786 | +--------> network address
2787 +------------------> owner of this subnet
2788 ------------------------------------------------------------------
2791 In case a connection between two daemons is closed or broken, DEL_EDGE messages
2792 are sent to inform the other daemons of that fact. Each daemon will calculate a
2793 new route to the the daemons, or mark them unreachable if there isn't any.
2800 ------------------------------------------------------------------
2801 REQ_KEY origin destination
2802 | +--> name of the tinc daemon it wants the key from
2803 +----------> name of the daemon that wants the key
2805 ANS_KEY origin destination 4ae0b0a82d6e0078 91 64 4
2806 | | \______________/ | | +--> MAC length
2807 | | | | +-----> digest algorithm
2808 | | | +--------> cipher algorithm
2809 | | +--> 128 bits key
2810 | +--> name of the daemon that wants the key
2811 +----------> name of the daemon that uses this key
2814 +--> daemon that has changed it's packet key
2815 ------------------------------------------------------------------
2818 The keys used to encrypt VPN packets are not sent out directly. This is
2819 because it would generate a lot of traffic on VPNs with many daemons, and
2820 chances are that not every tinc daemon will ever send a packet to every
2821 other daemon. Instead, if a daemon needs a key it sends a request for it
2822 via the meta connection of the nearest hop in the direction of the
2829 ------------------------------------------------------------------
2832 ------------------------------------------------------------------
2835 There is also a mechanism to check if hosts are still alive. Since network
2836 failures or a crash can cause a daemon to be killed without properly
2837 shutting down the TCP connection, this is necessary to keep an up to date
2838 connection list. PINGs are sent at regular intervals, except when there
2839 is also some other traffic. A little bit of salt (random data) is added
2840 with each PING and PONG message, to make sure that long sequences of PING/PONG
2841 messages without any other traffic won't result in known plaintext.
2843 This basically covers what is sent over the meta connection by tinc.
2846 @c ==================================================================
2852 Tinc got its name from ``TINC,'' short for @emph{There Is No Cabal}; the
2853 alleged Cabal was/is an organisation that was said to keep an eye on the
2854 entire Internet. As this is exactly what you @emph{don't} want, we named
2855 the tinc project after TINC.
2858 But in order to be ``immune'' to eavesdropping, you'll have to encrypt
2859 your data. Because tinc is a @emph{Secure} VPN (SVPN) daemon, it does
2860 exactly that: encrypt.
2861 However, encryption in itself does not prevent an attacker from modifying the encrypted data.
2862 Therefore, tinc also authenticates the data.
2863 Finally, tinc uses sequence numbers (which themselves are also authenticated) to prevent an attacker from replaying valid packets.
2865 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.
2866 The SPTPS protocol is designed to address some weaknesses in the legacy protocol.
2867 The new authentication protocol is used when two nodes connect to each other that both have the ExperimentalProtocol option set to yes,
2868 otherwise the legacy protocol will be used.
2871 * Legacy authentication protocol::
2872 * Simple Peer-to-Peer Security::
2873 * Encryption of network packets::
2878 @c ==================================================================
2879 @node Legacy authentication protocol
2880 @subsection Legacy authentication protocol
2882 @cindex legacy authentication protocol
2891 --------------------------------------------------------------------------
2892 client <attempts connection>
2894 server <accepts connection>
2896 client ID client 17.2
2897 | | +-> minor protocol version
2898 | +----> major protocol version
2899 +--------> name of tinc daemon
2901 server ID server 17.2
2902 | | +-> minor protocol version
2903 | +----> major protocol version
2904 +--------> name of tinc daemon
2906 client META_KEY 94 64 0 0 5f0823a93e35b69e...7086ec7866ce582b
2907 | | | | \_________________________________/
2908 | | | | +-> RSAKEYLEN bits totally random string S1,
2909 | | | | encrypted with server's public RSA key
2910 | | | +-> compression level
2911 | | +---> MAC length
2912 | +------> digest algorithm NID
2913 +---------> cipher algorithm NID
2915 server META_KEY 94 64 0 0 6ab9c1640388f8f0...45d1a07f8a672630
2916 | | | | \_________________________________/
2917 | | | | +-> RSAKEYLEN bits totally random string S2,
2918 | | | | encrypted with client's public RSA key
2919 | | | +-> compression level
2920 | | +---> MAC length
2921 | +------> digest algorithm NID
2922 +---------> cipher algorithm NID
2923 --------------------------------------------------------------------------
2926 The protocol allows each side to specify encryption algorithms and parameters,
2927 but in practice they are always fixed, since older versions of tinc did not
2928 allow them to be different from the default values. The cipher is always
2929 Blowfish in OFB mode, the digest is SHA1, but the MAC length is zero and no
2930 compression is used.
2934 @item the client will symmetrically encrypt outgoing traffic using S1
2935 @item the server will symmetrically encrypt outgoing traffic using S2
2939 --------------------------------------------------------------------------
2940 client CHALLENGE da02add1817c1920989ba6ae2a49cecbda0
2941 \_________________________________/
2942 +-> CHALLEN bits totally random string H1
2944 server CHALLENGE 57fb4b2ccd70d6bb35a64c142f47e61d57f
2945 \_________________________________/
2946 +-> CHALLEN bits totally random string H2
2948 client CHAL_REPLY 816a86
2949 +-> 160 bits SHA1 of H2
2951 server CHAL_REPLY 928ffe
2952 +-> 160 bits SHA1 of H1
2954 After the correct challenge replies are received, both ends have proved
2955 their identity. Further information is exchanged.
2957 client ACK 655 123 0
2959 | +----> estimated weight
2960 +--------> listening port of client
2962 server ACK 655 321 0
2964 | +----> estimated weight
2965 +--------> listening port of server
2966 --------------------------------------------------------------------------
2969 This legacy authentication protocol has several weaknesses, pointed out by security export Peter Gutmann.
2970 First, data is encrypted with RSA without padding.
2971 Padding schemes are designed to prevent attacks when the size of the plaintext is not equal to the size of the RSA key.
2972 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.
2973 There might be timing or other side-channel attacks against RSA encryption and decryption, tinc does not employ any protection against those.
2974 Furthermore, both sides send identical messages to each other, there is no distinction between server and client,
2975 which could make a MITM attack easier.
2976 However, no exploit is known in which a third party who is not already trusted by other nodes in the VPN could gain access.
2977 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.
2978 In other words, the legacy protocol does not provide perfect forward secrecy.
2980 @c ==================================================================
2981 @node Simple Peer-to-Peer Security
2982 @subsection Simple Peer-to-Peer Security
2985 The SPTPS protocol is designed to address the weaknesses in the legacy protocol.
2986 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.
2987 Instead, SPTPS always uses a very strong cipher suite:
2988 peers authenticate each other using 521 bits ECC keys,
2989 Diffie-Hellman using ephemeral 521 bits ECC keys is used to provide perfect forward secrecy (PFS),
2990 AES-256-CTR is used for encryption, and HMAC-SHA-256 for message authentication.
2992 Similar to TLS, messages are split up in records.
2993 A complete logical record contains the following information:
2996 @item uint32_t seqno (network byte order)
2997 @item uint16_t length (network byte order)
2999 @item opaque data[length]
3000 @item opaque hmac[HMAC_SIZE] (HMAC over all preceding fields)
3003 Depending on whether SPTPS records are sent via TCP or UDP, either the seqno or the length field is omitted on the wire
3004 (but they are still included in the calculation of the HMAC);
3005 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;
3006 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.
3008 The type field is used to distinguish between application records or handshake records.
3009 Types 0 to 127 are application records, type 128 is a handshake record, and types 129 to 255 are reserved.
3011 Before the initial handshake, no fields are encrypted, and the HMAC field is not present.
3012 After the authentication handshake, the length (if present), type and data fields are encrypted, and the HMAC field is present.
3013 For UDP packets, the seqno field is not encrypted, as it is used to determine the value of the counter used for encryption.
3015 The authentication consists of an exchange of Key EXchange, SIGnature and ACKnowledge messages, transmitted using type 128 records.
3021 ---------------------
3027 ...encrypt and HMAC using session keys from now on...
3034 ...key renegotiation starts here...
3043 ...encrypt and HMAC using new session keys from now on...
3049 ---------------------
3052 Note that the responder does not need to wait before it receives the first KEX message,
3053 it can immediately send its own once it has accepted an incoming connection.
3055 Key EXchange message:
3058 @item uint8_t kex_version (always 0 in this version of SPTPS)
3059 @item opaque nonce[32] (random number)
3060 @item opaque ecdh_key[ECDH_SIZE]
3066 @item opaque ecdsa_signature[ECDSA_SIZE]
3069 ACKnowledge message:
3072 @item empty (only sent after key renegotiation)
3078 @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.
3079 @item After receiving the other's KEX message, both KEX messages are concatenated (see below),
3080 and the result is signed using ECDSA.
3081 The result is sent to the other.
3082 @item After receiving the other's SIG message, the signature is verified.
3083 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.
3084 @item The shared secret key is expanded using a PRF.
3085 Both nonces and the application specific label are also used as input for the PRF.
3086 @item An ACK message is sent only when doing key renegotiation, and is sent using the old encryption keys.
3087 @item The expanded key is used to key the encryption and HMAC algorithms.
3090 The signature is calculated over this string:
3093 @item uint8_t initiator (0 = local peer, 1 = remote peer is initiator)
3094 @item opaque remote_kex_message[1 + 32 + ECDH_SIZE]
3095 @item opaque local_kex_message[1 + 32 + ECDH_SIZE]
3096 @item opaque label[label_length]
3099 The PRF is calculated as follows:
3102 @item A HMAC using SHA512 is used, the shared secret is used as the key.
3103 @item For each block of 64 bytes, a HMAC is calculated. For block n: hmac[n] =
3104 HMAC_SHA512(hmac[n - 1] + seed)
3105 @item For the first block (n = 1), hmac[0] is given by HMAC_SHA512(zeroes + seed),
3106 where zeroes is a block of 64 zero bytes.
3109 The seed is as follows:
3112 @item const char[13] "key expansion"
3113 @item opaque responder_nonce[32]
3114 @item opaque initiator_nonce[32]
3115 @item opaque label[label_length]
3118 The expanded key is used as follows:
3121 @item opaque responder_cipher_key[CIPHER_KEYSIZE]
3122 @item opaque responder_digest_key[DIGEST_KEYSIZE]
3123 @item opaque initiator_cipher_key[CIPHER_KEYSIZE]
3124 @item opaque initiator_digest_key[DIGEST_KEYSIZE]
3127 Where initiator_cipher_key is the key used by session initiator to encrypt
3128 messages sent to the responder.
3130 When using 256 bits Ed25519 keys, the AES-256-CTR cipher and HMAC-SHA-256 digest algorithm,
3131 the sizes are as follows:
3134 ECDH_SIZE: 32 (= 256/8)
3135 ECDSA_SIZE: 64 (= 2 * 256/8)
3136 CIPHER_KEYSIZE: 48 (= 256/8 + 128/8)
3137 DIGEST_KEYSIZE: 32 (= 256/8)
3140 Note that the cipher key also includes the initial value for the counter.
3142 @c ==================================================================
3143 @node Encryption of network packets
3144 @subsection Encryption of network packets
3147 A data packet can only be sent if the encryption key is known to both
3148 parties, and the connection is activated. If the encryption key is not
3149 known, a request is sent to the destination using the meta connection
3153 The UDP packets can be either encrypted with the legacy protocol or with SPTPS.
3154 In case of the legacy protocol, the UDP packet containing the network packet from the VPN has the following layout:
3157 ... | IP header | UDP header | seqno | VPN packet | MAC | UDP trailer
3158 \___________________/\_____/
3160 V +---> digest algorithm
3161 Encrypted with symmetric cipher
3167 So, the entire VPN packet is encrypted using a symmetric cipher, including a 32 bits
3168 sequence number that is added in front of the actual VPN packet, to act as a unique
3169 IV for each packet and to prevent replay attacks. A message authentication code
3170 is added to the UDP packet to prevent alteration of packets.
3171 Tinc by default encrypts network packets using Blowfish with 128 bit keys in CBC mode
3172 and uses 4 byte long message authentication codes to make sure
3173 eavesdroppers cannot get and cannot change any information at all from the
3174 packets they can intercept. The encryption algorithm and message authentication
3175 algorithm can be changed in the configuration. The length of the message
3176 authentication codes is also adjustable. The length of the key for the
3177 encryption algorithm is always the default length used by OpenSSL.
3179 The SPTPS protocol is described in @ref{Simple Peer-to-Peer Security}.
3180 For comparison, this is how SPTPS UDP packets look:
3183 ... | IP header | UDP header | seqno | type | VPN packet | MAC | UDP trailer
3184 \__________________/\_____/
3186 V +---> digest algorithm
3187 Encrypted with symmetric cipher
3190 The difference is that the seqno is not encrypted, since the encryption cipher is used in CTR mode,
3191 and therefore the seqno must be known before the packet can be decrypted.
3192 Furthermore, the MAC is never truncated.
3193 The SPTPS protocol always uses the AES-256-CTR cipher and HMAC-SHA-256 digest,
3194 this cannot be changed.
3197 @c ==================================================================
3198 @node Security issues
3199 @subsection Security issues
3201 In August 2000, we discovered the existence of a security hole in all versions
3202 of tinc up to and including 1.0pre2. This had to do with the way we exchanged
3203 keys. Since then, we have been working on a new authentication scheme to make
3204 tinc as secure as possible. The current version uses the OpenSSL library and
3205 uses strong authentication with RSA keys.
3207 On the 29th of December 2001, Jerome Etienne posted a security analysis of tinc
3208 1.0pre4. Due to a lack of sequence numbers and a message authentication code
3209 for each packet, an attacker could possibly disrupt certain network services or
3210 launch a denial of service attack by replaying intercepted packets. The current
3211 version adds sequence numbers and message authentication codes to prevent such
3214 On the 15th of September 2003, Peter Gutmann posted a security analysis of tinc
3215 1.0.1. He argues that the 32 bit sequence number used by tinc is not a good IV,
3216 that tinc's default length of 4 bytes for the MAC is too short, and he doesn't
3217 like tinc's use of RSA during authentication. We do not know of a security hole
3218 in the legacy protocol of tinc, but it is not as strong as TLS or IPsec.
3220 This version of tinc comes with an improved protocol, called Simple Peer-to-Peer Security,
3221 which aims to be as strong as TLS with one of the strongest cipher suites.
3223 Cryptography is a hard thing to get right. We cannot make any
3224 guarantees. Time, review and feedback are the only things that can
3225 prove the security of any cryptographic product. If you wish to review
3226 tinc or give us feedback, you are stronly encouraged to do so.
3229 @c ==================================================================
3230 @node Platform specific information
3231 @chapter Platform specific information
3234 * Interface configuration::
3238 @c ==================================================================
3239 @node Interface configuration
3240 @section Interface configuration
3242 When configuring an interface, one normally assigns it an address and a
3243 netmask. The address uniquely identifies the host on the network attached to
3244 the interface. The netmask, combined with the address, forms a subnet. It is
3245 used to add a route to the routing table instructing the kernel to send all
3246 packets which fall into that subnet to that interface. Because all packets for
3247 the entire VPN should go to the virtual network interface used by tinc, the
3248 netmask should be such that it encompasses the entire VPN.
3252 @multitable {Darwin (MacOS/X)} {ifconfig route add -bla network address netmask netmask prefixlength interface}
3254 @tab @code{ifconfig} @var{interface} @var{address} @code{netmask} @var{netmask}
3255 @item Linux iproute2
3256 @tab @code{ip addr add} @var{address}@code{/}@var{prefixlength} @code{dev} @var{interface}
3258 @tab @code{ifconfig} @var{interface} @var{address} @code{netmask} @var{netmask}
3260 @tab @code{ifconfig} @var{interface} @var{address} @code{netmask} @var{netmask}
3262 @tab @code{ifconfig} @var{interface} @var{address} @code{netmask} @var{netmask}
3264 @tab @code{ifconfig} @var{interface} @var{address} @code{netmask} @var{netmask}
3265 @item Darwin (MacOS/X)
3266 @tab @code{ifconfig} @var{interface} @var{address} @code{netmask} @var{netmask}
3268 @tab @code{netsh interface ip set address} @var{interface} @code{static} @var{address} @var{netmask}
3273 @multitable {Darwin (MacOS/X)} {ifconfig route add -bla network address netmask netmask prefixlength interface}
3275 @tab @code{ifconfig} @var{interface} @code{add} @var{address}@code{/}@var{prefixlength}
3277 @tab @code{ifconfig} @var{interface} @code{inet6} @var{address} @code{prefixlen} @var{prefixlength}
3279 @tab @code{ifconfig} @var{interface} @code{inet6} @var{address} @code{prefixlen} @var{prefixlength}
3281 @tab @code{ifconfig} @var{interface} @code{inet6} @var{address} @code{prefixlen} @var{prefixlength}
3283 @tab @code{ifconfig} @var{interface} @code{inet6 plumb up}
3285 @tab @code{ifconfig} @var{interface} @code{inet6 addif} @var{address} @var{address}
3286 @item Darwin (MacOS/X)
3287 @tab @code{ifconfig} @var{interface} @code{inet6} @var{address} @code{prefixlen} @var{prefixlength}
3289 @tab @code{netsh interface ipv6 add address} @var{interface} @code{static} @var{address}/@var{prefixlength}
3292 On some platforms, when running tinc in switch mode, the VPN interface must be set to tap mode with an ifconfig command:
3294 @multitable {Darwin (MacOS/X)} {ifconfig route add -bla network address netmask netmask prefixlength interface}
3296 @tab @code{ifconfig} @var{interface} @code{link0}
3299 On Linux, it is possible to create a persistent tun/tap interface which will
3300 continue to exist even if tinc quit, although this is normally not required.
3301 It can be useful to set up a tun/tap interface owned by a non-root user, so
3302 tinc can be started without needing any root privileges at all.
3304 @multitable {Darwin (MacOS/X)} {ifconfig route add -bla network address netmask netmask prefixlength interface}
3306 @tab @code{ip tuntap add dev} @var{interface} @code{mode} @var{tun|tap} @code{user} @var{username}
3309 @c ==================================================================
3313 In some cases it might be necessary to add more routes to the virtual network
3314 interface. There are two ways to indicate which interface a packet should go
3315 to, one is to use the name of the interface itself, another way is to specify
3316 the (local) address that is assigned to that interface (@var{local_address}). The
3317 former way is unambiguous and therefore preferable, but not all platforms
3320 Adding routes to IPv4 subnets:
3322 @multitable {Darwin (MacOS/X)} {ifconfig route add -bla network address netmask netmask prefixlength interface}
3324 @tab @code{route add -net} @var{network_address} @code{netmask} @var{netmask} @var{interface}
3325 @item Linux iproute2
3326 @tab @code{ip route add} @var{network_address}@code{/}@var{prefixlength} @code{dev} @var{interface}
3328 @tab @code{route add} @var{network_address}@code{/}@var{prefixlength} @var{local_address}
3330 @tab @code{route add} @var{network_address}@code{/}@var{prefixlength} @var{local_address}
3332 @tab @code{route add} @var{network_address}@code{/}@var{prefixlength} @var{local_address}
3334 @tab @code{route add} @var{network_address}@code{/}@var{prefixlength} @var{local_address} @code{-interface}
3335 @item Darwin (MacOS/X)
3336 @tab @code{route add} @var{network_address}@code{/}@var{prefixlength} @var{local_address}
3338 @tab @code{netsh routing ip add persistentroute} @var{network_address} @var{netmask} @var{interface} @var{local_address}
3341 Adding routes to IPv6 subnets:
3343 @multitable {Darwin (MacOS/X)} {ifconfig route add -bla network address netmask netmask prefixlength interface}
3345 @tab @code{route add -A inet6} @var{network_address}@code{/}@var{prefixlength} @var{interface}
3346 @item Linux iproute2
3347 @tab @code{ip route add} @var{network_address}@code{/}@var{prefixlength} @code{dev} @var{interface}
3349 @tab @code{route add -inet6} @var{network_address}@code{/}@var{prefixlength} @var{local_address}
3351 @tab @code{route add -inet6} @var{network_address} @var{local_address} @code{-prefixlen} @var{prefixlength}
3353 @tab @code{route add -inet6} @var{network_address} @var{local_address} @code{-prefixlen} @var{prefixlength}
3355 @tab @code{route add -inet6} @var{network_address}@code{/}@var{prefixlength} @var{local_address} @code{-interface}
3356 @item Darwin (MacOS/X)
3359 @tab @code{netsh interface ipv6 add route} @var{network address}/@var{prefixlength} @var{interface}
3363 @c ==================================================================
3369 * Contact information::
3374 @c ==================================================================
3375 @node Contact information
3376 @section Contact information
3379 Tinc's website is at @url{http://www.tinc-vpn.org/},
3380 this server is located in the Netherlands.
3383 We have an IRC channel on the FreeNode and OFTC IRC networks. Connect to
3384 @uref{http://www.freenode.net/, irc.freenode.net}
3386 @uref{http://www.oftc.net/, irc.oftc.net}
3387 and join channel #tinc.
3390 @c ==================================================================
3395 @item Ivo Timmermans (zarq)
3396 @item Guus Sliepen (guus) (@email{guus@@tinc-vpn.org})
3399 We have received a lot of valuable input from users. With their help,
3400 tinc has become the flexible and robust tool that it is today. We have
3401 composed a list of contributions, in the file called @file{THANKS} in
3402 the source distribution.
3405 @c ==================================================================
3407 @unnumbered Concept Index
3409 @c ==================================================================
3413 @c ==================================================================