1 \input texinfo @c -*-texinfo-*-
8 @include tincinclude.texi
11 @dircategory Networking tools
13 * tinc: (tinc). The tinc Manual.
16 This is the info manual for @value{PACKAGE} version @value{VERSION}, a Virtual Private Network daemon.
18 Copyright @copyright{} 1998-2016 Ivo Timmermans,
19 Guus Sliepen <guus@@tinc-vpn.org> and
20 Wessel Dankers <wsl@@tinc-vpn.org>.
22 Permission is granted to make and distribute verbatim copies of this
23 manual provided the copyright notice and this permission notice are
24 preserved on all copies.
26 Permission is granted to copy and distribute modified versions of this
27 manual under the conditions for verbatim copying, provided that the
28 entire resulting derived work is distributed under the terms of a
29 permission notice identical to this one.
35 @subtitle Setting up a Virtual Private Network with tinc
36 @author Ivo Timmermans and Guus Sliepen
39 @vskip 0pt plus 1filll
40 This is the info manual for @value{PACKAGE} version @value{VERSION}, a Virtual Private Network daemon.
42 Copyright @copyright{} 1998-2016 Ivo Timmermans,
43 Guus Sliepen <guus@@tinc-vpn.org> and
44 Wessel Dankers <wsl@@tinc-vpn.org>.
46 Permission is granted to make and distribute verbatim copies of this
47 manual provided the copyright notice and this permission notice are
48 preserved on all copies.
50 Permission is granted to copy and distribute modified versions of this
51 manual under the conditions for verbatim copying, provided that the
52 entire resulting derived work is distributed under the terms of a
53 permission notice identical to this one.
58 @c ==================================================================
68 * Technical information::
69 * Platform specific information::
71 * Concept Index:: All used terms explained
75 @c ==================================================================
80 Tinc is a Virtual Private Network (VPN) daemon that uses tunneling and
81 encryption to create a secure private network between hosts on the
84 Because the tunnel appears to the IP level network code as a normal
85 network device, there is no need to adapt any existing software.
86 The encrypted tunnels allows VPN sites to share information with each other
87 over the Internet without exposing any information to others.
89 This document is the manual for tinc. Included are chapters on how to
90 configure your computer to use tinc, as well as the configuration
91 process of tinc itself.
94 * Virtual Private Networks::
96 * Supported platforms::
99 @c ==================================================================
100 @node Virtual Private Networks
101 @section Virtual Private Networks
104 A Virtual Private Network or VPN is a network that can only be accessed
105 by a few elected computers that participate. This goal is achievable in
106 more than just one way.
109 Private networks can consist of a single stand-alone Ethernet LAN. Or
110 even two computers hooked up using a null-modem cable. In these cases,
112 obvious that the network is @emph{private}, no one can access it from the
113 outside. But if your computers are linked to the Internet, the network
114 is not private anymore, unless one uses firewalls to block all private
115 traffic. But then, there is no way to send private data to trusted
116 computers on the other end of the Internet.
119 This problem can be solved by using @emph{virtual} networks. Virtual
120 networks can live on top of other networks, but they use encapsulation to
121 keep using their private address space so they do not interfere with
122 the Internet. Mostly, virtual networks appear like a single LAN, even though
123 they can span the entire world. But virtual networks can't be secured
124 by using firewalls, because the traffic that flows through it has to go
125 through the Internet, where other people can look at it.
127 As is the case with either type of VPN, anybody could eavesdrop. Or
128 worse, alter data. Hence it's probably advisable to encrypt the data
129 that flows over the network.
131 When one introduces encryption, we can form a true VPN. Other people may
132 see encrypted traffic, but if they don't know how to decipher it (they
133 need to know the key for that), they cannot read the information that flows
134 through the VPN. This is what tinc was made for.
137 @c ==================================================================
142 I really don't quite remember what got us started, but it must have been
143 Guus' idea. He wrote a simple implementation (about 50 lines of C) that
144 used the ethertap device that Linux knows of since somewhere
145 about kernel 2.1.60. It didn't work immediately and he improved it a
146 bit. At this stage, the project was still simply called "vpnd".
148 Since then, a lot has changed---to say the least.
151 Tinc now supports encryption, it consists of a single daemon (tincd) for
152 both the receiving and sending end, it has become largely
153 runtime-configurable---in short, it has become a full-fledged
154 professional package.
156 @cindex traditional VPNs
158 Tinc also allows more than two sites to connect to eachother and form a single VPN.
159 Traditionally VPNs are created by making tunnels, which only have two endpoints.
160 Larger VPNs with more sites are created by adding more tunnels.
161 Tinc takes another approach: only endpoints are specified,
162 the software itself will take care of creating the tunnels.
163 This allows for easier configuration and improved scalability.
165 A lot can---and will be---changed. We have a number of things that we would like to
166 see in the future releases of tinc. Not everything will be available in
167 the near future. Our first objective is to make tinc work perfectly as
168 it stands, and then add more advanced features.
170 Meanwhile, we're always open-minded towards new ideas. And we're
174 @c ==================================================================
175 @node Supported platforms
176 @section Supported platforms
179 Tinc has been verified to work under Linux, FreeBSD, OpenBSD, NetBSD, Mac OS X (Darwin), Solaris, and Windows (both natively and in a Cygwin environment),
180 with various hardware architectures. These are some of the platforms
181 that are supported by the universal tun/tap device driver or other virtual network device drivers.
182 Without such a driver, tinc will most
183 likely compile and run, but it will not be able to send or receive data
187 For an up to date list of supported platforms, please check the list on
189 @uref{http://www.tinc-vpn.org/platforms/}.
197 @c Preparing your system
204 @c ==================================================================
206 @chapter Preparations
208 This chapter contains information on how to prepare your system to
212 * Configuring the kernel::
217 @c ==================================================================
218 @node Configuring the kernel
219 @section Configuring the kernel
222 * Configuration of Linux kernels::
223 * Configuration of FreeBSD kernels::
224 * Configuration of OpenBSD kernels::
225 * Configuration of NetBSD kernels::
226 * Configuration of Solaris kernels::
227 * Configuration of Darwin (Mac OS X) kernels::
228 * Configuration of Windows::
232 @c ==================================================================
233 @node Configuration of Linux kernels
234 @subsection Configuration of Linux kernels
236 @cindex Universal tun/tap
237 For tinc to work, you need a kernel that supports the Universal tun/tap device.
238 Most distributions come with kernels that already support this.
239 Here are the options you have to turn on when configuring a new kernel:
242 Code maturity level options
243 [*] Prompt for development and/or incomplete code/drivers
244 Network device support
245 <M> Universal tun/tap device driver support
248 It's not necessary to compile this driver as a module, even if you are going to
249 run more than one instance of tinc.
251 If you decide to build the tun/tap driver as a kernel module, add these lines
252 to @file{/etc/modules.conf}:
255 alias char-major-10-200 tun
259 @c ==================================================================
260 @node Configuration of FreeBSD kernels
261 @subsection Configuration of FreeBSD kernels
263 For FreeBSD version 4.1 and higher, tun and tap drivers are included in the default kernel configuration.
264 The tap driver can be loaded with @code{kldload if_tap}, or by adding @code{if_tap_load="YES"} to @file{/boot/loader.conf}.
267 @c ==================================================================
268 @node Configuration of OpenBSD kernels
269 @subsection Configuration of OpenBSD kernels
271 For OpenBSD version 2.9 and higher,
272 the tun driver is included in the default kernel configuration.
273 There is also a kernel patch from @uref{http://diehard.n-r-g.com/stuff/openbsd/}
274 which adds a tap device to OpenBSD which should work with tinc,
275 but with recent versions of OpenBSD,
276 a tun device can act as a tap device by setting the link0 option with ifconfig.
279 @c ==================================================================
280 @node Configuration of NetBSD kernels
281 @subsection Configuration of NetBSD kernels
283 For NetBSD version 1.5.2 and higher,
284 the tun driver is included in the default kernel configuration.
286 Tunneling IPv6 may not work on NetBSD's tun device.
289 @c ==================================================================
290 @node Configuration of Solaris kernels
291 @subsection Configuration of Solaris kernels
293 For Solaris 8 (SunOS 5.8) and higher,
294 the tun driver may or may not be included in the default kernel configuration.
295 If it isn't, the source can be downloaded from @uref{http://vtun.sourceforge.net/tun/}.
296 For x86 and sparc64 architectures, precompiled versions can be found at @uref{http://www.monkey.org/~dugsong/fragroute/}.
297 If the @file{net/if_tun.h} header file is missing, install it from the source package.
300 @c ==================================================================
301 @node Configuration of Darwin (Mac OS X) kernels
302 @subsection Configuration of Darwin (Mac OS X) kernels
304 Tinc on Darwin relies on a tunnel driver for its data acquisition from the kernel.
305 OS X version 10.6.8 and later have a built-in tun driver called "utun".
306 Tinc also supports the driver from @uref{http://tuntaposx.sourceforge.net/},
307 which supports both tun and tap style devices.
309 By default, tinc expects the tuntaposx driver to be installed.
310 To use the utun driver, set add @code{Device = utunX} to @file{tinc.conf},
311 where X is the desired number for the utun interface.
312 You can also omit the number, in which case the first free number will be chosen.
315 @c ==================================================================
316 @node Configuration of Windows
317 @subsection Configuration of Windows
319 You will need to install the latest TAP-Win32 driver from OpenVPN.
320 You can download it from @uref{http://openvpn.sourceforge.net}.
321 Using the Network Connections control panel,
322 configure the TAP-Win32 network interface in the same way as you would do from the tinc-up script,
323 as explained in the rest of the documentation.
326 @c ==================================================================
332 Before you can configure or build tinc, you need to have the LibreSSL or OpenSSL,
333 zlib and lzo libraries installed on your system. If you try to configure tinc without
334 having them installed, configure will give you an error message, and stop.
343 @c ==================================================================
344 @node LibreSSL/OpenSSL
345 @subsection LibreSSL/OpenSSL
349 For all cryptography-related functions, tinc uses the functions provided
350 by the LibreSSL or the OpenSSL library.
352 If this library is not installed, you will get an error when configuring
353 tinc for build. Support for running tinc with other cryptographic libraries
354 installed @emph{may} be added in the future.
356 You can use your operating system's package manager to install this if
357 available. Make sure you install the development AND runtime versions
360 If your operating system comes neither with LibreSSL or OpenSSL, you have to
361 install one manually. It is recommended that you get the latest version of
362 LibreSSL from @url{http://www.libressl.org/}. Instructions on how to
363 configure, build and install this package are included within the package.
364 Please make sure you build development and runtime libraries (which is the
367 If you installed the LibreSSL or OpenSSL libraries from source, it may be necessary
368 to let configure know where they are, by passing configure one of the
369 --with-openssl-* parameters. Note that you even have to use --with-openssl-* if you
373 --with-openssl=DIR LibreSSL/OpenSSL library and headers prefix
374 --with-openssl-include=DIR LibreSSL/OpenSSL headers directory
375 (Default is OPENSSL_DIR/include)
376 --with-openssl-lib=DIR LibreSSL/OpenSSL library directory
377 (Default is OPENSSL_DIR/lib)
381 @subsubheading License
384 The complete source code of tinc is covered by the GNU GPL version 2.
385 Since the license under which OpenSSL is distributed is not directly
386 compatible with the terms of the GNU GPL
387 @uref{http://www.openssl.org/support/faq.html#LEGAL2}, we
388 include an exemption to the GPL (see also the file COPYING.README) to allow
389 everyone to create a statically or dynamically linked executable:
392 This program is released under the GPL with the additional exemption
393 that compiling, linking, and/or using OpenSSL is allowed. You may
394 provide binary packages linked to the OpenSSL libraries, provided that
395 all other requirements of the GPL are met.
398 Since the LZO library used by tinc is also covered by the GPL,
399 we also present the following exemption:
402 Hereby I grant a special exception to the tinc VPN project
403 (http://www.tinc-vpn.org/) to link the LZO library with the OpenSSL library
404 (http://www.openssl.org).
406 Markus F.X.J. Oberhumer
410 @c ==================================================================
415 For the optional compression of UDP packets, tinc uses the functions provided
418 If this library is not installed, you will get an error when running the
419 configure script. You can either install the zlib library, or disable support
420 for zlib compression by using the "--disable-zlib" option when running the
421 configure script. Note that if you disable support for zlib, the resulting
422 binary will not work correctly on VPNs where zlib compression is used.
424 You can use your operating system's package manager to install this if
425 available. Make sure you install the development AND runtime versions
428 If you have to install zlib manually, you can get the source code
429 from @url{http://www.gzip.org/zlib/}. Instructions on how to configure,
430 build and install this package are included within the package. Please
431 make sure you build development and runtime libraries (which is the
435 @c ==================================================================
440 Another form of compression is offered using the LZO library.
442 If this library is not installed, you will get an error when running the
443 configure script. You can either install the LZO library, or disable support
444 for LZO compression by using the "--disable-lzo" option when running the
445 configure script. Note that if you disable support for LZO, the resulting
446 binary will not work correctly on VPNs where LZO compression is used.
448 You can use your operating system's package manager to install this if
449 available. Make sure you install the development AND runtime versions
452 If you have to install lzo manually, you can get the source code
453 from @url{http://www.oberhumer.com/opensource/lzo/}. Instructions on how to configure,
454 build and install this package are included within the package. Please
455 make sure you build development and runtime libraries (which is the
468 @c ==================================================================
470 @chapter Installation
472 If you use Debian, you may want to install one of the
473 precompiled packages for your system. These packages are equipped with
474 system startup scripts and sample configurations.
476 If you cannot use one of the precompiled packages, or you want to compile tinc
477 for yourself, you can use the source. The source is distributed under
478 the GNU General Public License (GPL). Download the source from the
479 @uref{http://www.tinc-vpn.org/download/, download page}, which has
480 the checksums of these files listed; you may wish to check these with
481 md5sum before continuing.
483 Tinc comes in a convenient autoconf/automake package, which you can just
484 treat the same as any other package. Which is just untar it, type
485 `./configure' and then `make'.
486 More detailed instructions are in the file @file{INSTALL}, which is
487 included in the source distribution.
490 * Building and installing tinc::
495 @c ==================================================================
496 @node Building and installing tinc
497 @section Building and installing tinc
499 Detailed instructions on configuring the source, building tinc and installing tinc
500 can be found in the file called @file{INSTALL}.
502 @cindex binary package
503 If you happen to have a binary package for tinc for your distribution,
504 you can use the package management tools of that distribution to install tinc.
505 The documentation that comes along with your distribution will tell you how to do that.
508 * Darwin (Mac OS X) build environment::
509 * Cygwin (Windows) build environment::
510 * MinGW (Windows) build environment::
514 @c ==================================================================
515 @node Darwin (Mac OS X) build environment
516 @subsection Darwin (Mac OS X) build environment
518 In order to build tinc on Darwin, you need to install the Mac OS X Developer Tools
519 from @uref{http://developer.apple.com/tools/macosxtools.html} and
520 preferably a recent version of Fink from @uref{http://www.finkproject.org/}.
522 After installation use fink to download and install the following packages:
523 autoconf25, automake, dlcompat, m4, openssl, zlib and lzo.
525 @c ==================================================================
526 @node Cygwin (Windows) build environment
527 @subsection Cygwin (Windows) build environment
529 If Cygwin hasn't already been installed, install it directly from
530 @uref{http://www.cygwin.com/}.
532 When tinc is compiled in a Cygwin environment, it can only be run in this environment,
533 but all programs, including those started outside the Cygwin environment, will be able to use the VPN.
534 It will also support all features.
536 @c ==================================================================
537 @node MinGW (Windows) build environment
538 @subsection MinGW (Windows) build environment
540 You will need to install the MinGW environment from @uref{http://www.mingw.org}.
542 When tinc is compiled using MinGW it runs natively under Windows,
543 it is not necessary to keep MinGW installed.
545 When detaching, tinc will install itself as a service,
546 which will be restarted automatically after reboots.
549 @c ==================================================================
551 @section System files
553 Before you can run tinc, you must make sure you have all the needed
554 files on your system.
562 @c ==================================================================
564 @subsection Device files
567 Most operating systems nowadays come with the necessary device files by default,
568 or they have a mechanism to create them on demand.
570 If you use Linux and do not have udev installed,
571 you may need to create the following device file if it does not exist:
574 mknod -m 600 /dev/net/tun c 10 200
578 @c ==================================================================
580 @subsection Other files
582 @subsubheading @file{/etc/networks}
584 You may add a line to @file{/etc/networks} so that your VPN will get a
585 symbolic name. For example:
591 @subsubheading @file{/etc/services}
594 You may add this line to @file{/etc/services}. The effect is that you
595 may supply a @samp{tinc} as a valid port number to some programs. The
596 number 655 is registered with the IANA.
601 # Ivo Timmermans <ivo@@tinc-vpn.org>
616 @c ==================================================================
618 @chapter Configuration
621 * Configuration introduction::
622 * Multiple networks::
623 * How connections work::
624 * Configuration files::
625 * Generating keypairs::
626 * Network interfaces::
627 * Example configuration::
630 @c ==================================================================
631 @node Configuration introduction
632 @section Configuration introduction
634 Before actually starting to configure tinc and editing files,
635 make sure you have read this entire section so you know what to expect.
636 Then, make it clear to yourself how you want to organize your VPN:
637 What are the nodes (computers running tinc)?
638 What IP addresses/subnets do they have?
639 What is the network mask of the entire VPN?
640 Do you need special firewall rules?
641 Do you have to set up masquerading or forwarding rules?
642 Do you want to run tinc in router mode or switch mode?
643 These questions can only be answered by yourself,
644 you will not find the answers in this documentation.
645 Make sure you have an adequate understanding of networks in general.
646 @cindex Network Administrators Guide
647 A good resource on networking is the
648 @uref{http://www.tldp.org/LDP/nag2/, Linux Network Administrators Guide}.
650 If you have everything clearly pictured in your mind,
651 proceed in the following order:
652 First, generate the configuration files (@file{tinc.conf}, your host configuration file, @file{tinc-up} and perhaps @file{tinc-down}).
653 Then generate the keypairs.
654 Finally, distribute the host configuration files.
655 These steps are described in the subsections below.
658 @c ==================================================================
659 @node Multiple networks
660 @section Multiple networks
662 @cindex multiple networks
664 In order to allow you to run more than one tinc daemon on one computer,
665 for instance if your computer is part of more than one VPN,
666 you can assign a @var{netname} to your VPN.
667 It is not required if you only run one tinc daemon,
668 it doesn't even have to be the same on all the sites of your VPN,
669 but it is recommended that you choose one anyway.
671 We will assume you use a netname throughout this document.
672 This means that you call tincd with the -n argument,
673 which will assign a netname to this daemon.
675 The effect of this is that the daemon will set its configuration
676 root to @file{@value{sysconfdir}/tinc/@var{netname}/}, where @var{netname} is your argument to the -n
677 option. You'll notice that it appears in syslog as @file{tinc.@var{netname}}.
679 However, it is not strictly necessary that you call tinc with the -n
680 option. In this case, the network name would just be empty, and it will
681 be used as such. tinc now looks for files in @file{@value{sysconfdir}/tinc/}, instead of
682 @file{@value{sysconfdir}/tinc/@var{netname}/}; the configuration file should be @file{@value{sysconfdir}/tinc/tinc.conf},
683 and the host configuration files are now expected to be in @file{@value{sysconfdir}/tinc/hosts/}.
685 But it is highly recommended that you use this feature of tinc, because
686 it will be so much clearer whom your daemon talks to. Hence, we will
687 assume that you use it.
690 @c ==================================================================
691 @node How connections work
692 @section How connections work
694 When tinc starts up, it parses the command-line options and then
695 reads in the configuration file tinc.conf.
696 If it sees one or more `ConnectTo' values pointing to other tinc daemons in that file,
697 it will try to connect to those other daemons.
698 Whether this succeeds or not and whether `ConnectTo' is specified or not,
699 tinc will listen for incoming connection from other daemons.
700 If you did specify a `ConnectTo' value and the other side is not responding,
701 tinc will keep retrying.
702 This means that once started, tinc will stay running until you tell it to stop,
703 and failures to connect to other tinc daemons will not stop your tinc daemon
704 for trying again later.
705 This means you don't have to intervene if there are temporary network problems.
709 There is no real distinction between a server and a client in tinc.
710 If you wish, you can view a tinc daemon without a `ConnectTo' value as a server,
711 and one which does specify such a value as a client.
712 It does not matter if two tinc daemons have a `ConnectTo' value pointing to each other however.
715 @c ==================================================================
716 @node Configuration files
717 @section Configuration files
719 The actual configuration of the daemon is done in the file
720 @file{@value{sysconfdir}/tinc/@var{netname}/tinc.conf} and at least one other file in the directory
721 @file{@value{sysconfdir}/tinc/@var{netname}/hosts/}.
723 An optional directory @file{@value{sysconfdir}/tinc/@var{netname}/conf.d} can be added from which
724 any .conf file will be read.
726 These file consists of comments (lines started with a #) or assignments
733 The variable names are case insensitive, and any spaces, tabs, newlines
734 and carriage returns are ignored. Note: it is not required that you put
735 in the `=' sign, but doing so improves readability. If you leave it
736 out, remember to replace it with at least one space character.
738 The server configuration is complemented with host specific configuration (see
739 the next section). Although all host configuration options for the local node
740 listed in this document can also be put in
741 @file{@value{sysconfdir}/tinc/@var{netname}/tinc.conf}, it is recommended to
742 put host specific configuration options in the host configuration file, as this
743 makes it easy to exchange with other nodes.
745 In this section all valid variables are listed in alphabetical order.
746 The default value is given between parentheses,
747 other comments are between square brackets.
750 * Main configuration variables::
751 * Host configuration variables::
757 @c ==================================================================
758 @node Main configuration variables
759 @subsection Main configuration variables
762 @cindex AddressFamily
763 @item AddressFamily = <ipv4|ipv6|any> (any)
764 This option affects the address family of listening and outgoing sockets.
765 If any is selected, then depending on the operating system
766 both IPv4 and IPv6 or just IPv6 listening sockets will be created.
768 @cindex BindToAddress
769 @item BindToAddress = <@var{address}> [<@var{port}>] [experimental]
770 If your computer has more than one IPv4 or IPv6 address, tinc
771 will by default listen on all of them for incoming connections.
772 Multiple BindToAddress variables may be specified,
773 in which case listening sockets for each specified address are made.
775 If no @var{port} is specified, the socket will be bound to the port specified by the Port option,
776 or to port 655 if neither is given.
777 To only bind to a specific port but not to a specific address, use "*" for the @var{address}.
779 This option may not work on all platforms.
781 @cindex BindToInterface
782 @item BindToInterface = <@var{interface}> [experimental]
783 If you have more than one network interface in your computer, tinc will
784 by default listen on all of them for incoming connections. It is
785 possible to bind tinc to a single interface like eth0 or ppp0 with this
788 This option may not work on all platforms.
791 @item Broadcast = <no | mst | direct> (mst) [experimental]
792 This option selects the way broadcast packets are sent to other daemons.
793 @emph{NOTE: all nodes in a VPN must use the same Broadcast mode, otherwise routing loops can form.}
797 Broadcast packets are never sent to other nodes.
800 Broadcast packets are sent and forwarded via the VPN's Minimum Spanning Tree.
801 This ensures broadcast packets reach all nodes.
804 Broadcast packets are sent directly to all nodes that can be reached directly.
805 Broadcast packets received from other nodes are never forwarded.
806 If the IndirectData option is also set, broadcast packets will only be sent to nodes which we have a meta connection to.
810 @item ConnectTo = <@var{name}>
811 Specifies which other tinc daemon to connect to on startup.
812 Multiple ConnectTo variables may be specified,
813 in which case outgoing connections to each specified tinc daemon are made.
814 The names should be known to this tinc daemon
815 (i.e., there should be a host configuration file for the name on the ConnectTo line).
817 If you don't specify a host with ConnectTo,
818 tinc won't try to connect to other daemons at all,
819 and will instead just listen for incoming connections.
822 @item DecrementTTL = <yes | no> (no) [experimental]
823 When enabled, tinc will decrement the Time To Live field in IPv4 packets, or the Hop Limit field in IPv6 packets,
824 before forwarding a received packet to the virtual network device or to another node,
825 and will drop packets that have a TTL value of zero,
826 in which case it will send an ICMP Time Exceeded packet back.
828 Do not use this option if you use switch mode and want to use IPv6.
831 @item Device = <@var{device}> (@file{/dev/tap0}, @file{/dev/net/tun} or other depending on platform)
832 The virtual network device to use.
833 Tinc will automatically detect what kind of device it is.
834 Under Windows, use @var{Interface} instead of @var{Device}.
835 Note that you can only use one device per daemon.
836 See also @ref{Device files}.
839 @item DeviceType = <@var{type}> (platform dependent)
840 The type of the virtual network device.
841 Tinc will normally automatically select the right type of tun/tap interface, and this option should not be used.
842 However, this option can be used to select one of the special interface types, if support for them is compiled in.
847 Use a dummy interface.
848 No packets are ever read or written to a virtual network device.
849 Useful for testing, or when setting up a node that only forwards packets for other nodes.
853 Open a raw socket, and bind it to a pre-existing
854 @var{Interface} (eth0 by default).
855 All packets are read from this interface.
856 Packets received for the local node are written to the raw socket.
857 However, at least on Linux, the operating system does not process IP packets destined for the local host.
861 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}.
862 Packets are read from and written to this multicast socket.
863 This can be used to connect to UML, QEMU or KVM instances listening on the same multicast address.
864 Do NOT connect multiple tinc daemons to the same multicast address, this will very likely cause routing loops.
865 Also note that this can cause decrypted VPN packets to be sent out on a real network if misconfigured.
868 @item uml (not compiled in by default)
869 Create a UNIX socket with the filename specified by
870 @var{Device}, or @file{@value{localstatedir}/run/@var{netname}.umlsocket}
872 Tinc will wait for a User Mode Linux instance to connect to this socket.
875 @item vde (not compiled in by default)
876 Uses the libvdeplug library to connect to a Virtual Distributed Ethernet switch,
877 using the UNIX socket specified by
878 @var{Device}, or @file{@value{localstatedir}/run/vde.ctl}
882 Also, in case tinc does not seem to correctly interpret packets received from the virtual network device,
883 it can be used to change the way packets are interpreted:
886 @item tun (BSD and Linux)
888 Depending on the platform, this can either be with or without an address family header (see below).
891 @item tunnohead (BSD)
892 Set type to tun without an address family header.
893 Tinc will expect packets read from the virtual network device to start with an IP header.
894 On some platforms IPv6 packets cannot be read from or written to the device in this mode.
897 @item tunifhead (BSD)
898 Set type to tun with an address family header.
899 Tinc will expect packets read from the virtual network device
900 to start with a four byte header containing the address family,
901 followed by an IP header.
902 This mode should support both IPv4 and IPv6 packets.
907 This is only supported on OS X version 10.6.8 and higher, but doesn't require the tuntaposx module.
908 This mode should support both IPv4 and IPv6 packets.
910 @item tap (BSD and Linux)
912 Tinc will expect packets read from the virtual network device
913 to start with an Ethernet header.
917 @item DirectOnly = <yes|no> (no) [experimental]
918 When this option is enabled, packets that cannot be sent directly to the destination node,
919 but which would have to be forwarded by an intermediate node, are dropped instead.
920 When combined with the IndirectData option,
921 packets for nodes for which we do not have a meta connection with are also dropped.
924 @item Forwarding = <off|internal|kernel> (internal) [experimental]
925 This option selects the way indirect packets are forwarded.
929 Incoming packets that are not meant for the local node,
930 but which should be forwarded to another node, are dropped.
933 Incoming packets that are meant for another node are forwarded by tinc internally.
935 This is the default mode, and unless you really know you need another forwarding mode, don't change it.
938 Incoming packets are always sent to the TUN/TAP device, even if the packets are not for the local node.
939 This is less efficient, but allows the kernel to apply its routing and firewall rules on them,
940 and can also help debugging.
943 @cindex GraphDumpFile
944 @item GraphDumpFile = <@var{filename}> [experimental]
945 If this option is present,
946 tinc will dump the current network graph to the file @var{filename}
947 every minute, unless there were no changes to the graph.
948 The file is in a format that can be read by graphviz tools.
949 If @var{filename} starts with a pipe symbol |,
950 then the rest of the filename is interpreted as a shell command
951 that is executed, the graph is then sent to stdin.
954 @item Hostnames = <yes|no> (no)
955 This option selects whether IP addresses (both real and on the VPN)
956 should be resolved. Since DNS lookups are blocking, it might affect
957 tinc's efficiency, even stopping the daemon for a few seconds every time
958 it does a lookup if your DNS server is not responding.
960 This does not affect resolving hostnames to IP addresses from the
961 configuration file, but whether hostnames should be resolved while logging.
964 @item IffOneQueue = <yes|no> (no) [experimental]
965 (Linux only) Set IFF_ONE_QUEUE flag on TUN/TAP devices.
968 @item Interface = <@var{interface}>
969 Defines the name of the interface corresponding to the virtual network device.
970 Depending on the operating system and the type of device this may or may not actually set the name of the interface.
971 Under Windows, this variable is used to select which network interface will be used.
972 If you specified a Device, this variable is almost always already correctly set.
975 @item KeyExpire = <@var{seconds}> (3600)
976 This option controls the time the encryption keys used to encrypt the data
977 are valid. It is common practice to change keys at regular intervals to
978 make it even harder for crackers, even though it is thought to be nearly
979 impossible to crack a single key.
981 @cindex LocalDiscovery
982 @item LocalDiscovery = <yes | no> (no) [experimental]
983 When enabled, tinc will try to detect peers that are on the same local network.
984 This will allow direct communication using LAN addresses, even if both peers are behind a NAT
985 and they only ConnectTo a third node outside the NAT,
986 which normally would prevent the peers from learning each other's LAN address.
988 Currently, local discovery is implemented by sending broadcast packets to the LAN during path MTU discovery.
989 This feature may not work in all possible situations.
992 @item MACExpire = <@var{seconds}> (600)
993 This option controls the amount of time MAC addresses are kept before they are removed.
994 This only has effect when Mode is set to "switch".
997 @item MaxTimeout = <@var{seconds}> (900)
998 This is the maximum delay before trying to reconnect to other tinc daemons.
1001 @item Mode = <router|switch|hub> (router)
1002 This option selects the way packets are routed to other daemons.
1008 variables in the host configuration files will be used to form a routing table.
1009 Only unicast packets of routable protocols (IPv4 and IPv6) are supported in this mode.
1011 This is the default mode, and unless you really know you need another mode, don't change it.
1015 In this mode the MAC addresses of the packets on the VPN will be used to
1016 dynamically create a routing table just like an Ethernet switch does.
1017 Unicast, multicast and broadcast packets of every protocol that runs over Ethernet are supported in this mode
1018 at the cost of frequent broadcast ARP requests and routing table updates.
1020 This mode is primarily useful if you want to bridge Ethernet segments.
1024 This mode is almost the same as the switch mode, but instead
1025 every packet will be broadcast to the other daemons
1026 while no routing table is managed.
1030 @item Name = <@var{name}> [required]
1031 This is a symbolic name for this connection.
1032 The name must consist only of alphanumeric and underscore characters (a-z, A-Z, 0-9 and _).
1034 If Name starts with a $, then the contents of the environment variable that follows will be used.
1035 In that case, invalid characters will be converted to underscores.
1036 If Name is $HOST, but no such environment variable exist,
1037 the hostname will be read using the gethostname() system call.
1039 @cindex PingInterval
1040 @item PingInterval = <@var{seconds}> (60)
1041 The number of seconds of inactivity that tinc will wait before sending a
1042 probe to the other end.
1045 @item PingTimeout = <@var{seconds}> (5)
1046 The number of seconds to wait for a response to pings or to allow meta
1047 connections to block. If the other end doesn't respond within this time,
1048 the connection is terminated, and the others will be notified of this.
1050 @cindex PriorityInheritance
1051 @item PriorityInheritance = <yes|no> (no) [experimental]
1052 When this option is enabled the value of the TOS field of tunneled IPv4 packets
1053 will be inherited by the UDP packets that are sent out.
1056 @item PrivateKey = <@var{key}> [obsolete]
1057 This is the RSA private key for tinc. However, for safety reasons it is
1058 advised to store private keys of any kind in separate files. This prevents
1059 accidental eavesdropping if you are editing the configuration file.
1061 @cindex PrivateKeyFile
1062 @item PrivateKeyFile = <@var{path}> (@file{@value{sysconfdir}/tinc/@var{netname}/rsa_key.priv})
1063 This is the full path name of the RSA private key file that was
1064 generated by @samp{tincd --generate-keys}. It must be a full path, not a
1067 @cindex ProcessPriority
1068 @item ProcessPriority = <low|normal|high>
1069 When this option is used the priority of the tincd process will be adjusted.
1070 Increasing the priority may help to reduce latency and packet loss on the VPN.
1073 @item Proxy = socks4 | socks5 | http | exec @var{...} [experimental]
1074 Use a proxy when making outgoing connections.
1075 The following proxy types are currently supported:
1079 @item socks4 <@var{address}> <@var{port}> [<@var{username}>]
1080 Connects to the proxy using the SOCKS version 4 protocol.
1081 Optionally, a @var{username} can be supplied which will be passed on to the proxy server.
1084 @item socks5 <@var{address}> <@var{port}> [<@var{username}> <@var{password}>]
1085 Connect to the proxy using the SOCKS version 5 protocol.
1086 If a @var{username} and @var{password} are given, basic username/password authentication will be used,
1087 otherwise no authentication will be used.
1090 @item http <@var{address}> <@var{port}>
1091 Connects to the proxy and sends a HTTP CONNECT request.
1094 @item exec <@var{command}>
1095 Executes the given command which should set up the outgoing connection.
1096 The environment variables @env{NAME}, @env{NODE}, @env{REMOTEADDRES} and @env{REMOTEPORT} are available.
1099 @cindex ReplayWindow
1100 @item ReplayWindow = <bytes> (16)
1101 This is the size of the replay tracking window for each remote node, in bytes.
1102 The window is a bitfield which tracks 1 packet per bit, so for example
1103 the default setting of 16 will track up to 128 packets in the window. In high
1104 bandwidth scenarios, setting this to a higher value can reduce packet loss from
1105 the interaction of replay tracking with underlying real packet loss and/or
1106 reordering. Setting this to zero will disable replay tracking completely and
1107 pass all traffic, but leaves tinc vulnerable to replay-based attacks on your
1110 @cindex StrictSubnets
1111 @item StrictSubnets = <yes|no> (no) [experimental]
1112 When this option is enabled tinc will only use Subnet statements which are
1113 present in the host config files in the local
1114 @file{@value{sysconfdir}/tinc/@var{netname}/hosts/} directory.
1115 Subnets learned via connections to other nodes and which are not
1116 present in the local host config files are ignored.
1118 @cindex TunnelServer
1119 @item TunnelServer = <yes|no> (no) [experimental]
1120 When this option is enabled tinc will no longer forward information between other tinc daemons,
1121 and will only allow connections with nodes for which host config files are present in the local
1122 @file{@value{sysconfdir}/tinc/@var{netname}/hosts/} directory.
1123 Setting this options also implicitly sets StrictSubnets.
1126 @item UDPRcvBuf = <bytes> (OS default)
1127 Sets the socket receive buffer size for the UDP socket, in bytes.
1128 If unset, the default buffer size will be used by the operating system.
1131 @item UDPSndBuf = <bytes> Pq OS default
1132 Sets the socket send buffer size for the UDP socket, in bytes.
1133 If unset, the default buffer size will be used by the operating system.
1138 @c ==================================================================
1139 @node Host configuration variables
1140 @subsection Host configuration variables
1144 @item Address = <@var{IP address}|@var{hostname}> [<port>] [recommended]
1145 This variable is only required if you want to connect to this host. It
1146 must resolve to the external IP address where the host can be reached,
1147 not the one that is internal to the VPN.
1148 If no port is specified, the default Port is used.
1149 Multiple Address variables can be specified, in which case each address will be
1150 tried until a working connection has been established.
1153 @item Cipher = <@var{cipher}> (blowfish)
1154 The symmetric cipher algorithm used to encrypt UDP packets.
1155 Any cipher supported by LibreSSL or OpenSSL is recognized.
1156 Furthermore, specifying "none" will turn off packet encryption.
1157 It is best to use only those ciphers which support CBC mode.
1160 @item ClampMSS = <yes|no> (yes)
1161 This option specifies whether tinc should clamp the maximum segment size (MSS)
1162 of TCP packets to the path MTU. This helps in situations where ICMP
1163 Fragmentation Needed or Packet too Big messages are dropped by firewalls.
1166 @item Compression = <@var{level}> (0)
1167 This option sets the level of compression used for UDP packets.
1168 Possible values are 0 (off), 1 (fast zlib) and any integer up to 9 (best zlib),
1169 10 (fast lzo) and 11 (best lzo).
1172 @item Digest = <@var{digest}> (sha1)
1173 The digest algorithm used to authenticate UDP packets.
1174 Any digest supported by LibreSSL or OpenSSL is recognized.
1175 Furthermore, specifying "none" will turn off packet authentication.
1177 @cindex IndirectData
1178 @item IndirectData = <yes|no> (no)
1179 This option specifies whether other tinc daemons besides the one you
1180 specified with ConnectTo can make a direct connection to you. This is
1181 especially useful if you are behind a firewall and it is impossible to
1182 make a connection from the outside to your tinc daemon. Otherwise, it
1183 is best to leave this option out or set it to no.
1186 @item MACLength = <@var{bytes}> (4)
1187 The length of the message authentication code used to authenticate UDP packets.
1188 Can be anything from 0
1189 up to the length of the digest produced by the digest algorithm.
1192 @item PMTU = <@var{mtu}> (1514)
1193 This option controls the initial path MTU to this node.
1195 @cindex PMTUDiscovery
1196 @item PMTUDiscovery = <yes|no> (yes)
1197 When this option is enabled, tinc will try to discover the path MTU to this node.
1198 After the path MTU has been discovered, it will be enforced on the VPN.
1201 @item Port = <@var{port}> (655)
1202 This is the port this tinc daemon listens on.
1203 You can use decimal portnumbers or symbolic names (as listed in @file{/etc/services}).
1206 @item PublicKey = <@var{key}> [obsolete]
1207 This is the RSA public key for this host.
1209 @cindex PublicKeyFile
1210 @item PublicKeyFile = <@var{path}> [obsolete]
1211 This is the full path name of the RSA public key file that was generated
1212 by @samp{tincd --generate-keys}. It must be a full path, not a relative
1216 From version 1.0pre4 on tinc will store the public key directly into the
1217 host configuration file in PEM format, the above two options then are not
1218 necessary. Either the PEM format is used, or exactly
1219 @strong{one of the above two options} must be specified
1220 in each host configuration file, if you want to be able to establish a
1221 connection with that host.
1224 @item Subnet = <@var{address}[/@var{prefixlength}[#@var{weight}]]>
1225 The subnet which this tinc daemon will serve.
1226 Tinc tries to look up which other daemon it should send a packet to by searching the appropriate subnet.
1227 If the packet matches a subnet,
1228 it will be sent to the daemon who has this subnet in his host configuration file.
1229 Multiple subnet lines can be specified for each daemon.
1231 Subnets can either be single MAC, IPv4 or IPv6 addresses,
1232 in which case a subnet consisting of only that single address is assumed,
1233 or they can be a IPv4 or IPv6 network address with a prefixlength.
1234 For example, IPv4 subnets must be in a form like 192.168.1.0/24,
1235 where 192.168.1.0 is the network address and 24 is the number of bits set in the netmask.
1236 Note that subnets like 192.168.1.1/24 are invalid!
1237 Read a networking HOWTO/FAQ/guide if you don't understand this.
1238 IPv6 subnets are notated like fec0:0:0:1::/64.
1239 MAC addresses are notated like 0:1a:2b:3c:4d:5e.
1241 @cindex CIDR notation
1242 Prefixlength is the number of bits set to 1 in the netmask part; for
1243 example: netmask 255.255.255.0 would become /24, 255.255.252.0 becomes
1244 /22. This conforms to standard CIDR notation as described in
1245 @uref{http://www.ietf.org/rfc/rfc1519.txt, RFC1519}
1247 @cindex Subnet weight
1248 A Subnet can be given a weight to indicate its priority over identical Subnets
1249 owned by different nodes. The default weight is 10. Lower values indicate
1250 higher priority. Packets will be sent to the node with the highest priority,
1251 unless that node is not reachable, in which case the node with the next highest
1252 priority will be tried, and so on.
1255 @item TCPonly = <yes|no> (no) [deprecated]
1256 If this variable is set to yes, then the packets are tunnelled over a
1257 TCP connection instead of a UDP connection. This is especially useful
1258 for those who want to run a tinc daemon from behind a masquerading
1259 firewall, or if UDP packet routing is disabled somehow.
1260 Setting this options also implicitly sets IndirectData.
1262 Since version 1.0.10, tinc will automatically detect whether communication via
1263 UDP is possible or not.
1267 @c ==================================================================
1272 Apart from reading the server and host configuration files,
1273 tinc can also run scripts at certain moments.
1274 Below is a list of filenames of scripts and a description of when they are run.
1275 A script is only run if it exists and if it is executable.
1277 Scripts are run synchronously;
1278 this means that tinc will temporarily stop processing packets until the called script finishes executing.
1279 This guarantees that scripts will execute in the exact same order as the events that trigger them.
1280 If you need to run commands asynchronously, you have to ensure yourself that they are being run in the background.
1282 Under Windows (not Cygwin), the scripts must have the extension .bat.
1286 @item @value{sysconfdir}/tinc/@var{netname}/tinc-up
1287 This is the most important script.
1288 If it is present it will be executed right after the tinc daemon has been
1289 started and has connected to the virtual network device.
1290 It should be used to set up the corresponding network interface,
1291 but can also be used to start other things.
1293 Under Windows you can use the Network Connections control panel instead of creating this script.
1296 @item @value{sysconfdir}/tinc/@var{netname}/tinc-down
1297 This script is started right before the tinc daemon quits.
1299 @item @value{sysconfdir}/tinc/@var{netname}/hosts/@var{host}-up
1300 This script is started when the tinc daemon with name @var{host} becomes reachable.
1302 @item @value{sysconfdir}/tinc/@var{netname}/hosts/@var{host}-down
1303 This script is started when the tinc daemon with name @var{host} becomes unreachable.
1305 @item @value{sysconfdir}/tinc/@var{netname}/host-up
1306 This script is started when any host becomes reachable.
1308 @item @value{sysconfdir}/tinc/@var{netname}/host-down
1309 This script is started when any host becomes unreachable.
1311 @item @value{sysconfdir}/tinc/@var{netname}/subnet-up
1312 This script is started when a subnet becomes reachable.
1313 The Subnet and the node it belongs to are passed in environment variables.
1315 @item @value{sysconfdir}/tinc/@var{netname}/subnet-down
1316 This script is started when a subnet becomes unreachable.
1319 @cindex environment variables
1320 The scripts are started without command line arguments,
1321 but can make use of certain environment variables.
1322 Under UNIX like operating systems the names of environment variables must be preceded by a $ in scripts.
1323 Under Windows, in @file{.bat} files, they have to be put between % signs.
1328 If a netname was specified, this environment variable contains it.
1332 Contains the name of this tinc daemon.
1336 Contains the name of the virtual network device that tinc uses.
1340 Contains the name of the virtual network interface that tinc uses.
1341 This should be used for commands like ifconfig.
1345 When a host becomes (un)reachable, this is set to its name.
1346 If a subnet becomes (un)reachable, this is set to the owner of that subnet.
1348 @cindex REMOTEADDRESS
1350 When a host becomes (un)reachable, this is set to its real address.
1354 When a host becomes (un)reachable,
1355 this is set to the port number it uses for communication with other tinc daemons.
1359 When a subnet becomes (un)reachable, this is set to the subnet.
1363 When a subnet becomes (un)reachable, this is set to the subnet weight.
1368 @c ==================================================================
1369 @node How to configure
1370 @subsection How to configure
1372 @subsubheading Step 1. Creating the main configuration file
1374 The main configuration file will be called @file{@value{sysconfdir}/tinc/@var{netname}/tinc.conf}.
1375 Adapt the following example to create a basic configuration file:
1378 Name = @var{yourname}
1379 Device = @file{/dev/tap0}
1382 Then, if you know to which other tinc daemon(s) yours is going to connect,
1383 add `ConnectTo' values.
1385 @subsubheading Step 2. Creating your host configuration file
1387 If you added a line containing `Name = yourname' in the main configuration file,
1388 you will need to create a host configuration file @file{@value{sysconfdir}/tinc/@var{netname}/hosts/yourname}.
1389 Adapt the following example to create a host configuration file:
1392 Address = your.real.hostname.org
1393 Subnet = 192.168.1.0/24
1396 You can also use an IP address instead of a hostname.
1397 The `Subnet' specifies the address range that is local for @emph{your part of the VPN only}.
1398 If you have multiple address ranges you can specify more than one `Subnet'.
1399 You might also need to add a `Port' if you want your tinc daemon to run on a different port number than the default (655).
1402 @c ==================================================================
1403 @node Generating keypairs
1404 @section Generating keypairs
1406 @cindex key generation
1407 Now that you have already created the main configuration file and your host configuration file,
1408 you can easily create a public/private keypair by entering the following command:
1411 tincd -n @var{netname} -K
1414 Tinc will generate a public and a private key and ask you where to put them.
1415 Just press enter to accept the defaults.
1418 @c ==================================================================
1419 @node Network interfaces
1420 @section Network interfaces
1422 Before tinc can start transmitting data over the tunnel, it must
1423 set up the virtual network interface.
1425 First, decide which IP addresses you want to have associated with these
1426 devices, and what network mask they must have.
1428 Tinc will open a virtual network device (@file{/dev/tun}, @file{/dev/tap0} or similar),
1429 which will also create a network interface called something like @samp{tun0}, @samp{tap0}.
1430 If you are using the Linux tun/tap driver, the network interface will by default have the same name as the @var{netname}.
1431 Under Windows you can change the name of the network interface from the Network Connections control panel.
1434 You can configure the network interface by putting ordinary ifconfig, route, and other commands
1435 to a script named @file{@value{sysconfdir}/tinc/@var{netname}/tinc-up}.
1436 When tinc starts, this script will be executed. When tinc exits, it will execute the script named
1437 @file{@value{sysconfdir}/tinc/@var{netname}/tinc-down}, but normally you don't need to create that script.
1439 An example @file{tinc-up} script:
1443 ifconfig $INTERFACE 192.168.1.1 netmask 255.255.0.0
1446 This script gives the interface an IP address and a netmask.
1447 The kernel will also automatically add a route to this interface, so normally you don't need
1448 to add route commands to the @file{tinc-up} script.
1449 The kernel will also bring the interface up after this command.
1451 The netmask is the mask of the @emph{entire} VPN network, not just your
1454 The exact syntax of the ifconfig and route commands differs from platform to platform.
1455 You can look up the commands for setting addresses and adding routes in @ref{Platform specific information},
1456 but it is best to consult the manpages of those utilities on your platform.
1459 @c ==================================================================
1460 @node Example configuration
1461 @section Example configuration
1465 Imagine the following situation. Branch A of our example `company' wants to connect
1466 three branch offices in B, C and D using the Internet. All four offices
1467 have a 24/7 connection to the Internet.
1469 A is going to serve as the center of the network. B and C will connect
1470 to A, and D will connect to C. Each office will be assigned their own IP
1474 A: net 10.1.0.0 mask 255.255.0.0 gateway 10.1.54.1 internet IP 1.2.3.4
1475 B: net 10.2.0.0 mask 255.255.0.0 gateway 10.2.1.12 internet IP 2.3.4.5
1476 C: net 10.3.0.0 mask 255.255.0.0 gateway 10.3.69.254 internet IP 3.4.5.6
1477 D: net 10.4.0.0 mask 255.255.0.0 gateway 10.4.3.32 internet IP 4.5.6.7
1480 Here, ``gateway'' is the VPN IP address of the machine that is running the
1481 tincd, and ``internet IP'' is the IP address of the firewall, which does not
1482 need to run tincd, but it must do a port forwarding of TCP and UDP on port
1483 655 (unless otherwise configured).
1485 In this example, it is assumed that eth0 is the interface that points to
1486 the inner (physical) LAN of the office, although this could also be the
1487 same as the interface that leads to the Internet. The configuration of
1488 the real interface is also shown as a comment, to give you an idea of
1489 how these example host is set up. All branches use the netname `company'
1490 for this particular VPN.
1492 @subsubheading For Branch A
1494 @emph{BranchA} would be configured like this:
1496 In @file{@value{sysconfdir}/tinc/company/tinc-up}:
1499 # Real interface of internal network:
1500 # ifconfig eth0 10.1.54.1 netmask 255.255.0.0
1502 ifconfig $INTERFACE 10.1.54.1 netmask 255.0.0.0
1505 and in @file{@value{sysconfdir}/tinc/company/tinc.conf}:
1512 On all hosts, @file{@value{sysconfdir}/tinc/company/hosts/BranchA} contains:
1515 Subnet = 10.1.0.0/16
1518 -----BEGIN RSA PUBLIC KEY-----
1520 -----END RSA PUBLIC KEY-----
1523 Note that the IP addresses of eth0 and tap0 are the same.
1524 This is quite possible, if you make sure that the netmasks of the interfaces are different.
1525 It is in fact recommended to give both real internal network interfaces and tap interfaces the same IP address,
1526 since that will make things a lot easier to remember and set up.
1529 @subsubheading For Branch B
1531 In @file{@value{sysconfdir}/tinc/company/tinc-up}:
1534 # Real interface of internal network:
1535 # ifconfig eth0 10.2.43.8 netmask 255.255.0.0
1537 ifconfig $INTERFACE 10.2.1.12 netmask 255.0.0.0
1540 and in @file{@value{sysconfdir}/tinc/company/tinc.conf}:
1547 Note here that the internal address (on eth0) doesn't have to be the
1548 same as on the tap0 device. Also, ConnectTo is given so that this node will
1549 always try to connect to BranchA.
1551 On all hosts, in @file{@value{sysconfdir}/tinc/company/hosts/BranchB}:
1554 Subnet = 10.2.0.0/16
1557 -----BEGIN RSA PUBLIC KEY-----
1559 -----END RSA PUBLIC KEY-----
1563 @subsubheading For Branch C
1565 In @file{@value{sysconfdir}/tinc/company/tinc-up}:
1568 # Real interface of internal network:
1569 # ifconfig eth0 10.3.69.254 netmask 255.255.0.0
1571 ifconfig $INTERFACE 10.3.69.254 netmask 255.0.0.0
1574 and in @file{@value{sysconfdir}/tinc/company/tinc.conf}:
1582 C already has another daemon that runs on port 655, so they have to
1583 reserve another port for tinc. It knows the portnumber it has to listen on
1584 from it's own host configuration file.
1586 On all hosts, in @file{@value{sysconfdir}/tinc/company/hosts/BranchC}:
1590 Subnet = 10.3.0.0/16
1593 -----BEGIN RSA PUBLIC KEY-----
1595 -----END RSA PUBLIC KEY-----
1599 @subsubheading For Branch D
1601 In @file{@value{sysconfdir}/tinc/company/tinc-up}:
1604 # Real interface of internal network:
1605 # ifconfig eth0 10.4.3.32 netmask 255.255.0.0
1607 ifconfig $INTERFACE 10.4.3.32 netmask 255.0.0.0
1610 and in @file{@value{sysconfdir}/tinc/company/tinc.conf}:
1615 Device = /dev/net/tun
1618 D will be connecting to C, which has a tincd running for this network on
1619 port 2000. It knows the port number from the host configuration file.
1620 Also note that since D uses the tun/tap driver, the network interface
1621 will not be called `tun' or `tap0' or something like that, but will
1622 have the same name as netname.
1624 On all hosts, in @file{@value{sysconfdir}/tinc/company/hosts/BranchD}:
1627 Subnet = 10.4.0.0/16
1630 -----BEGIN RSA PUBLIC KEY-----
1632 -----END RSA PUBLIC KEY-----
1635 @subsubheading Key files
1637 A, B, C and D all have generated a public/private keypair with the following command:
1643 The private key is stored in @file{@value{sysconfdir}/tinc/company/rsa_key.priv},
1644 the public key is put into the host configuration file in the @file{@value{sysconfdir}/tinc/company/hosts/} directory.
1645 During key generation, tinc automatically guesses the right filenames based on the -n option and
1646 the Name directive in the @file{tinc.conf} file (if it is available).
1648 @subsubheading Starting
1650 After each branch has finished configuration and they have distributed
1651 the host configuration files amongst them, they can start their tinc daemons.
1652 They don't necessarily have to wait for the other branches to have started
1653 their daemons, tinc will try connecting until they are available.
1656 @c ==================================================================
1658 @chapter Running tinc
1660 If everything else is done, you can start tinc by typing the following command:
1663 tincd -n @var{netname}
1667 Tinc will detach from the terminal and continue to run in the background like a good daemon.
1668 If there are any problems however you can try to increase the debug level
1669 and look in the syslog to find out what the problems are.
1675 * Solving problems::
1677 * Sending bug reports::
1681 @c ==================================================================
1682 @node Runtime options
1683 @section Runtime options
1685 Besides the settings in the configuration file, tinc also accepts some
1686 command line options.
1688 @cindex command line
1689 @cindex runtime options
1693 @item -c, --config=@var{path}
1694 Read configuration options from the directory @var{path}. The default is
1695 @file{@value{sysconfdir}/tinc/@var{netname}/}.
1697 @item -D, --no-detach
1698 Don't fork and detach.
1699 This will also disable the automatic restart mechanism for fatal errors.
1702 @item -d, --debug=@var{level}
1703 Set debug level to @var{level}. The higher the debug level, the more gets
1704 logged. Everything goes via syslog.
1706 @item -k, --kill[=@var{signal}]
1707 Attempt to kill a running tincd (optionally with the specified @var{signal} instead of SIGTERM) and exit.
1708 Use it in conjunction with the -n option to make sure you kill the right tinc daemon.
1709 Under native Windows the optional argument is ignored,
1710 the service will always be stopped and removed.
1712 @item -n, --net=@var{netname}
1713 Use configuration for net @var{netname}.
1714 This will let tinc read all configuration files from
1715 @file{@value{sysconfdir}/tinc/@var{netname}/}.
1716 Specifying . for @var{netname} is the same as not specifying any @var{netname}.
1717 @xref{Multiple networks}.
1719 @item -K, --generate-keys[=@var{bits}]
1720 Generate public/private keypair of @var{bits} length. If @var{bits} is not specified,
1721 2048 is the default. tinc will ask where you want to store the files,
1722 but will default to the configuration directory (you can use the -c or -n option
1723 in combination with -K). After that, tinc will quit.
1725 @item -o, --option=[@var{HOST}.]@var{KEY}=@var{VALUE}
1726 Without specifying a @var{HOST}, this will set server configuration variable @var{KEY} to @var{VALUE}.
1727 If specified as @var{HOST}.@var{KEY}=@var{VALUE},
1728 this will set the host configuration variable @var{KEY} of the host named @var{HOST} to @var{VALUE}.
1729 This option can be used more than once to specify multiple configuration variables.
1732 Lock tinc into main memory.
1733 This will prevent sensitive data like shared private keys to be written to the system swap files/partitions.
1735 @item --logfile[=@var{file}]
1736 Write log entries to a file instead of to the system logging facility.
1737 If @var{file} is omitted, the default is @file{@value{localstatedir}/log/tinc.@var{netname}.log}.
1739 @item --pidfile=@var{file}
1740 Write PID to @var{file} instead of @file{@value{localstatedir}/run/tinc.@var{netname}.pid}.
1742 @item --bypass-security
1743 Disables encryption and authentication.
1744 Only useful for debugging.
1747 Change process root directory to the directory where the config file is
1748 located (@file{@value{sysconfdir}/tinc/@var{netname}/} as determined by
1749 -n/--net option or as given by -c/--config option), for added security.
1750 The chroot is performed after all the initialization is done, after
1751 writing pid files and opening network sockets.
1753 Note that this option alone does not do any good without -U/--user, below.
1755 Note also that tinc can't run scripts anymore (such as tinc-down or host-up),
1756 unless it's setup to be runnable inside chroot environment.
1758 @item -U, --user=@var{user}
1759 Switch to the given @var{user} after initialization, at the same time as
1760 chroot is performed (see --chroot above). With this option tinc drops
1761 privileges, for added security.
1764 Display a short reminder of these runtime options and terminate.
1767 Output version information and exit.
1771 @c ==================================================================
1776 You can also send the following signals to a running tincd process:
1782 Forces tinc to try to connect to all uplinks immediately.
1783 Usually tinc attempts to do this itself,
1784 but increases the time it waits between the attempts each time it failed,
1785 and if tinc didn't succeed to connect to an uplink the first time after it started,
1786 it defaults to the maximum time of 15 minutes.
1789 Partially rereads configuration files.
1790 Connections to hosts whose host config file are removed are closed.
1791 New outgoing connections specified in @file{tinc.conf} will be made.
1792 If the --logfile option is used, this will also close and reopen the log file,
1793 useful when log rotation is used.
1796 Temporarily increases debug level to 5.
1797 Send this signal again to revert to the original level.
1800 Dumps the connection list to syslog.
1803 Dumps virtual network device statistics, all known nodes, edges and subnets to syslog.
1806 Purges all information remembered about unreachable nodes.
1810 @c ==================================================================
1812 @section Debug levels
1814 @cindex debug levels
1815 The tinc daemon can send a lot of messages to the syslog.
1816 The higher the debug level, the more messages it will log.
1817 Each level inherits all messages of the previous level:
1823 This will log a message indicating tinc has started along with a version number.
1824 It will also log any serious error.
1827 This will log all connections that are made with other tinc daemons.
1830 This will log status and error messages from scripts and other tinc daemons.
1833 This will log all requests that are exchanged with other tinc daemons. These include
1834 authentication, key exchange and connection list updates.
1837 This will log a copy of everything received on the meta socket.
1840 This will log all network traffic over the virtual private network.
1844 @c ==================================================================
1845 @node Solving problems
1846 @section Solving problems
1848 If tinc starts without problems, but if the VPN doesn't work, you will have to find the cause of the problem.
1849 The first thing to do is to start tinc with a high debug level in the foreground,
1850 so you can directly see everything tinc logs:
1853 tincd -n @var{netname} -d5 -D
1856 If tinc does not log any error messages, then you might want to check the following things:
1859 @item @file{tinc-up} script
1860 Does this script contain the right commands?
1861 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.
1864 Does the Subnet (or Subnets) in the host configuration file of this host match the portion of the VPN that belongs to this host?
1866 @item Firewalls and NATs
1867 Do you have a firewall or a NAT device (a masquerading firewall or perhaps an ADSL router that performs masquerading)?
1868 If so, check that it allows TCP and UDP traffic on port 655.
1869 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.
1870 You can add @samp{TCPOnly = yes} to your host config file to force tinc to only use a single TCP connection,
1871 this works through most firewalls and NATs. Since version 1.0.10, tinc will automatically fall back to TCP if direct communication via UDP is not possible.
1876 @c ==================================================================
1877 @node Error messages
1878 @section Error messages
1880 What follows is a list of the most common error messages you might find in the logs.
1881 Some of them will only be visible if the debug level is high enough.
1884 @item Could not open /dev/tap0: No such device
1887 @item You forgot to `modprobe netlink_dev' or `modprobe ethertap'.
1888 @item You forgot to compile `Netlink device emulation' in the kernel.
1891 @item Can't write to /dev/net/tun: No such device
1894 @item You forgot to `modprobe tun'.
1895 @item You forgot to compile `Universal TUN/TAP driver' in the kernel.
1896 @item The tun device is located somewhere else in @file{/dev/}.
1899 @item Network address and prefix length do not match!
1902 @item The Subnet field must contain a @emph{network} address, trailing bits should be 0.
1903 @item If you only want to use one IP address, set the netmask to /32.
1906 @item Error reading RSA key file `rsa_key.priv': No such file or directory
1909 @item You forgot to create a public/private keypair.
1910 @item Specify the complete pathname to the private key file with the @samp{PrivateKeyFile} option.
1913 @item Warning: insecure file permissions for RSA private key file `rsa_key.priv'!
1916 @item The private key file is readable by users other than root.
1917 Use chmod to correct the file permissions.
1920 @item Creating metasocket failed: Address family not supported
1923 @item By default tinc tries to create both IPv4 and IPv6 sockets.
1924 On some platforms this might not be implemented.
1925 If the logs show @samp{Ready} later on, then at least one metasocket was created,
1926 and you can ignore this message.
1927 You can add @samp{AddressFamily = ipv4} to @file{tinc.conf} to prevent this from happening.
1930 @item Cannot route packet: unknown IPv4 destination 1.2.3.4
1933 @item You try to send traffic to a host on the VPN for which no Subnet is known.
1934 @item If it is a broadcast address (ending in .255), it probably is a samba server or a Windows host sending broadcast packets.
1938 @item Cannot route packet: ARP request for unknown address 1.2.3.4
1941 @item You try to send traffic to a host on the VPN for which no Subnet is known.
1944 @item Packet with destination 1.2.3.4 is looping back to us!
1947 @item Something is not configured right. Packets are being sent out to the
1948 virtual network device, but according to the Subnet directives in your host configuration
1949 file, those packets should go to your own host. Most common mistake is that
1950 you have a Subnet line in your host configuration file with a prefix length which is
1951 just as large as the prefix of the virtual network interface. The latter should in almost all
1952 cases be larger. Rethink your configuration.
1953 Note that you will only see this message if you specified a debug
1954 level of 5 or higher!
1955 @item Chances are that a @samp{Subnet = ...} line in the host configuration file of this tinc daemon is wrong.
1956 Change it to a subnet that is accepted locally by another interface,
1957 or if that is not the case, try changing the prefix length into /32.
1960 @item Node foo (1.2.3.4) is not reachable
1963 @item Node foo does not have a connection anymore, its tinc daemon is not running or its connection to the Internet is broken.
1966 @item Received UDP packet from unknown source 1.2.3.4 (port 12345)
1969 @item If you see this only sporadically, it is harmless and caused by a node sending packets using an old key.
1972 @item Got bad/bogus/unauthorized REQUEST from foo (1.2.3.4 port 12345)
1975 @item Node foo does not have the right public/private keypair.
1976 Generate new keypairs and distribute them again.
1977 @item An attacker tries to gain access to your VPN.
1978 @item A network error caused corruption of metadata sent from foo.
1983 @c ==================================================================
1984 @node Sending bug reports
1985 @section Sending bug reports
1987 If you really can't find the cause of a problem, or if you suspect tinc is not working right,
1988 you can send us a bugreport, see @ref{Contact information}.
1989 Be sure to include the following information in your bugreport:
1992 @item A clear description of what you are trying to achieve and what the problem is.
1993 @item What platform (operating system, version, hardware architecture) and which version of tinc you use.
1994 @item If compiling tinc fails, a copy of @file{config.log} and the error messages you get.
1995 @item Otherwise, a copy of @file{tinc.conf}, @file{tinc-up} and all files in the @file{hosts/} directory.
1996 @item The output of the commands @samp{ifconfig -a} and @samp{route -n} (or @samp{netstat -rn} if that doesn't work).
1997 @item The output of any command that fails to work as it should (like ping or traceroute).
2000 @c ==================================================================
2001 @node Technical information
2002 @chapter Technical information
2007 * The meta-protocol::
2012 @c ==================================================================
2013 @node The connection
2014 @section The connection
2017 Tinc is a daemon that takes VPN data and transmit that to another host
2018 computer over the existing Internet infrastructure.
2022 * The meta-connection::
2026 @c ==================================================================
2027 @node The UDP tunnel
2028 @subsection The UDP tunnel
2030 @cindex virtual network device
2032 The data itself is read from a character device file, the so-called
2033 @emph{virtual network device}. This device is associated with a network
2034 interface. Any data sent to this interface can be read from the device,
2035 and any data written to the device gets sent from the interface.
2036 There are two possible types of virtual network devices:
2037 `tun' style, which are point-to-point devices which can only handle IPv4 and/or IPv6 packets,
2038 and `tap' style, which are Ethernet devices and handle complete Ethernet frames.
2040 So when tinc reads an Ethernet frame from the device, it determines its
2041 type. When tinc is in its default routing mode, it can handle IPv4 and IPv6
2042 packets. Depending on the Subnet lines, it will send the packets off to their destination IP address.
2043 In the `switch' and `hub' mode, tinc will use broadcasts and MAC address discovery
2044 to deduce the destination of the packets.
2045 Since the latter modes only depend on the link layer information,
2046 any protocol that runs over Ethernet is supported (for instance IPX and Appletalk).
2047 However, only `tap' style devices provide this information.
2049 After the destination has been determined,
2050 the packet will be compressed (optionally),
2051 a sequence number will be added to the packet,
2052 the packet will then be encrypted
2053 and a message authentication code will be appended.
2055 @cindex encapsulating
2057 When that is done, time has come to actually transport the
2058 packet to the destination computer. We do this by sending the packet
2059 over an UDP connection to the destination host. This is called
2060 @emph{encapsulating}, the VPN packet (though now encrypted) is
2061 encapsulated in another IP datagram.
2063 When the destination receives this packet, the same thing happens, only
2064 in reverse. So it checks the message authentication code, decrypts the contents of the UDP datagram,
2065 checks the sequence number
2066 and writes the decrypted information to its own virtual network device.
2068 If the virtual network device is a `tun' device (a point-to-point tunnel),
2069 there is no problem for the kernel to accept a packet.
2070 However, if it is a `tap' device (this is the only available type on FreeBSD),
2071 the destination MAC address must match that of the virtual network interface.
2072 If tinc is in its default routing mode, ARP does not work, so the correct destination MAC
2073 can not be known by the sending host.
2074 Tinc solves this by letting the receiving end detect the MAC address of its own virtual network interface
2075 and overwriting the destination MAC address of the received packet.
2077 In switch or hub modes ARP does work so the sender already knows the correct destination MAC address.
2078 In those modes every interface should have a unique MAC address, so make sure they are not the same.
2079 Because switch and hub modes rely on MAC addresses to function correctly,
2080 these modes cannot be used on the following operating systems which don't have a `tap' style virtual network device:
2081 OpenBSD, NetBSD, Darwin and Solaris.
2084 @c ==================================================================
2085 @node The meta-connection
2086 @subsection The meta-connection
2088 Having only a UDP connection available is not enough. Though suitable
2089 for transmitting data, we want to be able to reliably send other
2090 information, such as routing and session key information to somebody.
2093 TCP is a better alternative, because it already contains protection
2094 against information being lost, unlike UDP.
2096 So we establish two connections. One for the encrypted VPN data, and one
2097 for other information, the meta-data. Hence, we call the second
2098 connection the meta-connection. We can now be sure that the
2099 meta-information doesn't get lost on the way to another computer.
2101 @cindex data-protocol
2102 @cindex meta-protocol
2103 Like with any communication, we must have a protocol, so that everybody
2104 knows what everything stands for, and how she should react. Because we
2105 have two connections, we also have two protocols. The protocol used for
2106 the UDP data is the ``data-protocol,'' the other one is the
2109 The reason we don't use TCP for both protocols is that UDP is much
2110 better for encapsulation, even while it is less reliable. The real
2111 problem is that when TCP would be used to encapsulate a TCP stream
2112 that's on the private network, for every packet sent there would be
2113 three ACKs sent instead of just one. Furthermore, if there would be
2114 a timeout, both TCP streams would sense the timeout, and both would
2115 start re-sending packets.
2118 @c ==================================================================
2119 @node The meta-protocol
2120 @section The meta-protocol
2122 The meta protocol is used to tie all tinc daemons together, and
2123 exchange information about which tinc daemon serves which virtual
2126 The meta protocol consists of requests that can be sent to the other
2127 side. Each request has a unique number and several parameters. All
2128 requests are represented in the standard ASCII character set. It is
2129 possible to use tools such as telnet or netcat to connect to a tinc
2130 daemon started with the --bypass-security option
2131 and to read and write requests by hand, provided that one
2132 understands the numeric codes sent.
2134 The authentication scheme is described in @ref{Authentication protocol}. After a
2135 successful authentication, the server and the client will exchange all the
2136 information about other tinc daemons and subnets they know of, so that both
2137 sides (and all the other tinc daemons behind them) have their information
2144 ------------------------------------------------------------------
2145 ADD_EDGE node1 node2 21.32.43.54 655 222 0
2146 | | | | | +-> options
2147 | | | | +----> weight
2148 | | | +--------> UDP port of node2
2149 | | +----------------> real address of node2
2150 | +-------------------------> name of destination node
2151 +-------------------------------> name of source node
2153 ADD_SUBNET node 192.168.1.0/24
2154 | | +--> prefixlength
2155 | +--------> network address
2156 +------------------> owner of this subnet
2157 ------------------------------------------------------------------
2160 The ADD_EDGE messages are to inform other tinc daemons that a connection between
2161 two nodes exist. The address of the destination node is available so that
2162 VPN packets can be sent directly to that node.
2164 The ADD_SUBNET messages inform other tinc daemons that certain subnets belong
2165 to certain nodes. tinc will use it to determine to which node a VPN packet has
2172 ------------------------------------------------------------------
2173 DEL_EDGE node1 node2
2174 | +----> name of destination node
2175 +----------> name of source node
2177 DEL_SUBNET node 192.168.1.0/24
2178 | | +--> prefixlength
2179 | +--------> network address
2180 +------------------> owner of this subnet
2181 ------------------------------------------------------------------
2184 In case a connection between two daemons is closed or broken, DEL_EDGE messages
2185 are sent to inform the other daemons of that fact. Each daemon will calculate a
2186 new route to the the daemons, or mark them unreachable if there isn't any.
2193 ------------------------------------------------------------------
2194 REQ_KEY origin destination
2195 | +--> name of the tinc daemon it wants the key from
2196 +----------> name of the daemon that wants the key
2198 ANS_KEY origin destination 4ae0b0a82d6e0078 91 64 4
2199 | | \______________/ | | +--> MAC length
2200 | | | | +-----> digest algorithm
2201 | | | +--------> cipher algorithm
2202 | | +--> 128 bits key
2203 | +--> name of the daemon that wants the key
2204 +----------> name of the daemon that uses this key
2207 +--> daemon that has changed it's packet key
2208 ------------------------------------------------------------------
2211 The keys used to encrypt VPN packets are not sent out directly. This is
2212 because it would generate a lot of traffic on VPNs with many daemons, and
2213 chances are that not every tinc daemon will ever send a packet to every
2214 other daemon. Instead, if a daemon needs a key it sends a request for it
2215 via the meta connection of the nearest hop in the direction of the
2222 ------------------------------------------------------------------
2225 ------------------------------------------------------------------
2228 There is also a mechanism to check if hosts are still alive. Since network
2229 failures or a crash can cause a daemon to be killed without properly
2230 shutting down the TCP connection, this is necessary to keep an up to date
2231 connection list. PINGs are sent at regular intervals, except when there
2232 is also some other traffic. A little bit of salt (random data) is added
2233 with each PING and PONG message, to make sure that long sequences of PING/PONG
2234 messages without any other traffic won't result in known plaintext.
2236 This basically covers what is sent over the meta connection by tinc.
2239 @c ==================================================================
2245 Tinc got its name from ``TINC,'' short for @emph{There Is No Cabal}; the
2246 alleged Cabal was/is an organisation that was said to keep an eye on the
2247 entire Internet. As this is exactly what you @emph{don't} want, we named
2248 the tinc project after TINC.
2251 But in order to be ``immune'' to eavesdropping, you'll have to encrypt
2252 your data. Because tinc is a @emph{Secure} VPN (SVPN) daemon, it does
2253 exactly that: encrypt.
2254 Tinc by default uses blowfish encryption with 128 bit keys in CBC mode, 32 bit
2255 sequence numbers and 4 byte long message authentication codes to make sure
2256 eavesdroppers cannot get and cannot change any information at all from the
2257 packets they can intercept. The encryption algorithm and message authentication
2258 algorithm can be changed in the configuration. The length of the message
2259 authentication codes is also adjustable. The length of the key for the
2260 encryption algorithm is always the default length used by LibreSSL/OpenSSL.
2263 * Authentication protocol::
2264 * Encryption of network packets::
2269 @c ==================================================================
2270 @node Authentication protocol
2271 @subsection Authentication protocol
2273 @cindex authentication
2274 A new scheme for authentication in tinc has been devised, which offers some
2275 improvements over the protocol used in 1.0pre2 and 1.0pre3. Explanation is
2285 --------------------------------------------------------------------------
2286 client <attempts connection>
2288 server <accepts connection>
2292 +-------> name of tinc daemon
2296 +-------> name of tinc daemon
2298 client META_KEY 5f0823a93e35b69e...7086ec7866ce582b
2299 \_________________________________/
2300 +-> RSAKEYLEN bits totally random string S1,
2301 encrypted with server's public RSA key
2303 server META_KEY 6ab9c1640388f8f0...45d1a07f8a672630
2304 \_________________________________/
2305 +-> RSAKEYLEN bits totally random string S2,
2306 encrypted with client's public RSA key
2309 - the client will symmetrically encrypt outgoing traffic using S1
2310 - the server will symmetrically encrypt outgoing traffic using S2
2312 client CHALLENGE da02add1817c1920989ba6ae2a49cecbda0
2313 \_________________________________/
2314 +-> CHALLEN bits totally random string H1
2316 server CHALLENGE 57fb4b2ccd70d6bb35a64c142f47e61d57f
2317 \_________________________________/
2318 +-> CHALLEN bits totally random string H2
2320 client CHAL_REPLY 816a86
2321 +-> 160 bits SHA1 of H2
2323 server CHAL_REPLY 928ffe
2324 +-> 160 bits SHA1 of H1
2326 After the correct challenge replies are received, both ends have proved
2327 their identity. Further information is exchanged.
2329 client ACK 655 123 0
2331 | +----> estimated weight
2332 +--------> listening port of client
2334 server ACK 655 321 0
2336 | +----> estimated weight
2337 +--------> listening port of server
2338 --------------------------------------------------------------------------
2341 This new scheme has several improvements, both in efficiency and security.
2343 First of all, the server sends exactly the same kind of messages over the wire
2344 as the client. The previous versions of tinc first authenticated the client,
2345 and then the server. This scheme even allows both sides to send their messages
2346 simultaneously, there is no need to wait for the other to send something first.
2347 This means that any calculations that need to be done upon sending or receiving
2348 a message can also be done in parallel. This is especially important when doing
2349 RSA encryption/decryption. Given that these calculations are the main part of
2350 the CPU time spent for the authentication, speed is improved by a factor 2.
2352 Second, only one RSA encrypted message is sent instead of two. This reduces the
2353 amount of information attackers can see (and thus use for a cryptographic
2354 attack). It also improves speed by a factor two, making the total speedup a
2357 Third, and most important:
2358 The symmetric cipher keys are exchanged first, the challenge is done
2359 afterwards. In the previous authentication scheme, because a man-in-the-middle
2360 could pass the challenge/chal_reply phase (by just copying the messages between
2361 the two real tinc daemons), but no information was exchanged that was really
2362 needed to read the rest of the messages, the challenge/chal_reply phase was of
2363 no real use. The man-in-the-middle was only stopped by the fact that only after
2364 the ACK messages were encrypted with the symmetric cipher. Potentially, it
2365 could even send it's own symmetric key to the server (if it knew the server's
2366 public key) and read some of the metadata the server would send it (it was
2367 impossible for the mitm to read actual network packets though). The new scheme
2368 however prevents this.
2370 This new scheme makes sure that first of all, symmetric keys are exchanged. The
2371 rest of the messages are then encrypted with the symmetric cipher. Then, each
2372 side can only read received messages if they have their private key. The
2373 challenge is there to let the other side know that the private key is really
2374 known, because a challenge reply can only be sent back if the challenge is
2375 decrypted correctly, and that can only be done with knowledge of the private
2378 Fourth: the first thing that is sent via the symmetric cipher encrypted
2379 connection is a totally random string, so that there is no known plaintext (for
2380 an attacker) in the beginning of the encrypted stream.
2383 @c ==================================================================
2384 @node Encryption of network packets
2385 @subsection Encryption of network packets
2388 A data packet can only be sent if the encryption key is known to both
2389 parties, and the connection is activated. If the encryption key is not
2390 known, a request is sent to the destination using the meta connection
2391 to retrieve it. The packet is stored in a queue while waiting for the
2395 The UDP packet containing the network packet from the VPN has the following layout:
2398 ... | IP header | UDP header | seqno | VPN packet | MAC | UDP trailer
2399 \___________________/\_____/
2401 V +---> digest algorithm
2402 Encrypted with symmetric cipher
2405 So, the entire VPN packet is encrypted using a symmetric cipher, including a 32 bits
2406 sequence number that is added in front of the actual VPN packet, to act as a unique
2407 IV for each packet and to prevent replay attacks. A message authentication code
2408 is added to the UDP packet to prevent alteration of packets. By default the
2409 first 4 bytes of the digest are used for this, but this can be changed using
2410 the MACLength configuration variable.
2412 @c ==================================================================
2413 @node Security issues
2414 @subsection Security issues
2416 In August 2000, we discovered the existence of a security hole in all versions
2417 of tinc up to and including 1.0pre2. This had to do with the way we exchanged
2418 keys. Since then, we have been working on a new authentication scheme to make
2419 tinc as secure as possible. The current version uses the LibreSSL or OpenSSL library and
2420 uses strong authentication with RSA keys.
2422 On the 29th of December 2001, Jerome Etienne posted a security analysis of tinc
2423 1.0pre4. Due to a lack of sequence numbers and a message authentication code
2424 for each packet, an attacker could possibly disrupt certain network services or
2425 launch a denial of service attack by replaying intercepted packets. The current
2426 version adds sequence numbers and message authentication codes to prevent such
2429 On the 15th of September 2003, Peter Gutmann posted a security analysis of tinc
2430 1.0.1. He argues that the 32 bit sequence number used by tinc is not a good IV,
2431 that tinc's default length of 4 bytes for the MAC is too short, and he doesn't
2432 like tinc's use of RSA during authentication. We do not know of a security hole
2433 in this version of tinc, but tinc's security is not as strong as TLS or IPsec.
2434 We will address these issues in tinc 2.0.
2436 Cryptography is a hard thing to get right. We cannot make any
2437 guarantees. Time, review and feedback are the only things that can
2438 prove the security of any cryptographic product. If you wish to review
2439 tinc or give us feedback, you are stronly encouraged to do so.
2442 @c ==================================================================
2443 @node Platform specific information
2444 @chapter Platform specific information
2447 * Interface configuration::
2451 @c ==================================================================
2452 @node Interface configuration
2453 @section Interface configuration
2455 When configuring an interface, one normally assigns it an address and a
2456 netmask. The address uniquely identifies the host on the network attached to
2457 the interface. The netmask, combined with the address, forms a subnet. It is
2458 used to add a route to the routing table instructing the kernel to send all
2459 packets which fall into that subnet to that interface. Because all packets for
2460 the entire VPN should go to the virtual network interface used by tinc, the
2461 netmask should be such that it encompasses the entire VPN.
2465 @multitable {Darwin (Mac OS X)} {ifconfig route add -bla network address netmask netmask prefixlength interface}
2467 @tab @code{ifconfig} @var{interface} @var{address} @code{netmask} @var{netmask}
2468 @item Linux iproute2
2469 @tab @code{ip addr add} @var{address}@code{/}@var{prefixlength} @code{dev} @var{interface}
2471 @tab @code{ifconfig} @var{interface} @var{address} @code{netmask} @var{netmask}
2473 @tab @code{ifconfig} @var{interface} @var{address} @code{netmask} @var{netmask}
2475 @tab @code{ifconfig} @var{interface} @var{address} @code{netmask} @var{netmask}
2477 @tab @code{ifconfig} @var{interface} @var{address} @code{netmask} @var{netmask}
2478 @item Darwin (Mac OS X)
2479 @tab @code{ifconfig} @var{interface} @var{address} @code{netmask} @var{netmask}
2481 @tab @code{netsh interface ip set address} @var{interface} @code{static} @var{address} @var{netmask}
2486 @multitable {Darwin (Mac OS X)} {ifconfig route add -bla network address netmask netmask prefixlength interface}
2488 @tab @code{ifconfig} @var{interface} @code{add} @var{address}@code{/}@var{prefixlength}
2490 @tab @code{ifconfig} @var{interface} @code{inet6} @var{address} @code{prefixlen} @var{prefixlength}
2492 @tab @code{ifconfig} @var{interface} @code{inet6} @var{address} @code{prefixlen} @var{prefixlength}
2494 @tab @code{ifconfig} @var{interface} @code{inet6} @var{address} @code{prefixlen} @var{prefixlength}
2496 @tab @code{ifconfig} @var{interface} @code{inet6 plumb up}
2498 @tab @code{ifconfig} @var{interface} @code{inet6 addif} @var{address} @var{address}
2499 @item Darwin (Mac OS X)
2500 @tab @code{ifconfig} @var{interface} @code{inet6} @var{address} @code{prefixlen} @var{prefixlength}
2502 @tab @code{netsh interface ipv6 add address} @var{interface} @code{static} @var{address}/@var{prefixlength}
2505 On some platforms, when running tinc in switch mode, the VPN interface must be set to tap mode with an ifconfig command:
2507 @multitable {Darwin (Mac OS X)} {ifconfig route add -bla network address netmask netmask prefixlength interface}
2509 @tab @code{ifconfig} @var{interface} @code{link0}
2512 On Linux, it is possible to create a persistent tun/tap interface which will
2513 continue to exist even if tinc quit, although this is normally not required.
2514 It can be useful to set up a tun/tap interface owned by a non-root user, so
2515 tinc can be started without needing any root privileges at all.
2517 @multitable {Darwin (Mac OS X)} {ifconfig route add -bla network address netmask netmask prefixlength interface}
2519 @tab @code{ip tuntap add dev} @var{interface} @code{mode} @var{tun|tap} @code{user} @var{username}
2522 @c ==================================================================
2526 In some cases it might be necessary to add more routes to the virtual network
2527 interface. There are two ways to indicate which interface a packet should go
2528 to, one is to use the name of the interface itself, another way is to specify
2529 the (local) address that is assigned to that interface (@var{local_address}). The
2530 former way is unambiguous and therefore preferable, but not all platforms
2533 Adding routes to IPv4 subnets:
2535 @multitable {Darwin (Mac OS X)} {ifconfig route add -bla network address netmask netmask prefixlength interface}
2537 @tab @code{route add -net} @var{network_address} @code{netmask} @var{netmask} @var{interface}
2538 @item Linux iproute2
2539 @tab @code{ip route add} @var{network_address}@code{/}@var{prefixlength} @code{dev} @var{interface}
2541 @tab @code{route add} @var{network_address}@code{/}@var{prefixlength} @var{local_address}
2543 @tab @code{route add} @var{network_address}@code{/}@var{prefixlength} @var{local_address}
2545 @tab @code{route add} @var{network_address}@code{/}@var{prefixlength} @var{local_address}
2547 @tab @code{route add} @var{network_address}@code{/}@var{prefixlength} @var{local_address} @code{-interface}
2548 @item Darwin (Mac OS X)
2549 @tab @code{route add} @var{network_address}@code{/}@var{prefixlength} @code{-interface} @var{interface}
2551 @tab @code{netsh routing ip add persistentroute} @var{network_address} @var{netmask} @var{interface} @var{local_address}
2554 Adding routes to IPv6 subnets:
2556 @multitable {Darwin (Mac OS X)} {ifconfig route add -bla network address netmask netmask prefixlength interface}
2558 @tab @code{route add -A inet6} @var{network_address}@code{/}@var{prefixlength} @var{interface}
2559 @item Linux iproute2
2560 @tab @code{ip route add} @var{network_address}@code{/}@var{prefixlength} @code{dev} @var{interface}
2562 @tab @code{route add -inet6} @var{network_address}@code{/}@var{prefixlength} @var{local_address}
2564 @tab @code{route add -inet6} @var{network_address} @var{local_address} @code{-prefixlen} @var{prefixlength}
2566 @tab @code{route add -inet6} @var{network_address} @var{local_address} @code{-prefixlen} @var{prefixlength}
2568 @tab @code{route add -inet6} @var{network_address}@code{/}@var{prefixlength} @var{local_address} @code{-interface}
2569 @item Darwin (Mac OS X)
2570 @tab @code{route add -inet6} @var{network_address}@code{/}@var{prefixlength} @code{-interface} @var{interface}
2572 @tab @code{netsh interface ipv6 add route} @var{network address}/@var{prefixlength} @var{interface}
2576 @c ==================================================================
2582 * Contact information::
2587 @c ==================================================================
2588 @node Contact information
2589 @section Contact information
2592 Tinc's website is at @url{http://www.tinc-vpn.org/},
2593 this server is located in the Netherlands.
2596 We have an IRC channel on the FreeNode and OFTC IRC networks. Connect to
2597 @uref{http://www.freenode.net/, irc.freenode.net}
2599 @uref{http://www.oftc.net/, irc.oftc.net}
2600 and join channel #tinc.
2603 @c ==================================================================
2608 @item Ivo Timmermans (zarq)
2609 @item Guus Sliepen (guus) (@email{guus@@tinc-vpn.org})
2612 We have received a lot of valuable input from users. With their help,
2613 tinc has become the flexible and robust tool that it is today. We have
2614 composed a list of contributions, in the file called @file{THANKS} in
2615 the source distribution.
2618 @c ==================================================================
2620 @unnumbered Concept Index
2622 @c ==================================================================
2626 @c ==================================================================