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{} 1998-2012 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{} 1998-2012 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 ==================================================================
69 * Technical information::
70 * Platform specific information::
72 * Concept Index:: All used terms explained
76 @c ==================================================================
81 Tinc is a Virtual Private Network (VPN) daemon that uses tunneling and
82 encryption to create a secure private network between hosts on the
85 Because the tunnel appears to the IP level network code as a normal
86 network device, there is no need to adapt any existing software.
87 The encrypted tunnels allows VPN sites to share information with each other
88 over the Internet without exposing any information to others.
90 This document is the manual for tinc. Included are chapters on how to
91 configure your computer to use tinc, as well as the configuration
92 process of tinc itself.
95 * Virtual Private Networks::
97 * Supported platforms::
100 @c ==================================================================
101 @node Virtual Private Networks
102 @section Virtual Private Networks
105 A Virtual Private Network or VPN is a network that can only be accessed
106 by a few elected computers that participate. This goal is achievable in
107 more than just one way.
110 Private networks can consist of a single stand-alone Ethernet LAN. Or
111 even two computers hooked up using a null-modem cable. In these cases,
113 obvious that the network is @emph{private}, no one can access it from the
114 outside. But if your computers are linked to the Internet, the network
115 is not private anymore, unless one uses firewalls to block all private
116 traffic. But then, there is no way to send private data to trusted
117 computers on the other end of the Internet.
120 This problem can be solved by using @emph{virtual} networks. Virtual
121 networks can live on top of other networks, but they use encapsulation to
122 keep using their private address space so they do not interfere with
123 the Internet. Mostly, virtual networks appear like a single LAN, even though
124 they can span the entire world. But virtual networks can't be secured
125 by using firewalls, because the traffic that flows through it has to go
126 through the Internet, where other people can look at it.
128 As is the case with either type of VPN, anybody could eavesdrop. Or
129 worse, alter data. Hence it's probably advisable to encrypt the data
130 that flows over the network.
132 When one introduces encryption, we can form a true VPN. Other people may
133 see encrypted traffic, but if they don't know how to decipher it (they
134 need to know the key for that), they cannot read the information that flows
135 through the VPN. This is what tinc was made for.
138 @c ==================================================================
143 I really don't quite remember what got us started, but it must have been
144 Guus' idea. He wrote a simple implementation (about 50 lines of C) that
145 used the ethertap device that Linux knows of since somewhere
146 about kernel 2.1.60. It didn't work immediately and he improved it a
147 bit. At this stage, the project was still simply called "vpnd".
149 Since then, a lot has changed---to say the least.
152 Tinc now supports encryption, it consists of a single daemon (tincd) for
153 both the receiving and sending end, it has become largely
154 runtime-configurable---in short, it has become a full-fledged
155 professional package.
157 @cindex traditional VPNs
159 Tinc also allows more than two sites to connect to eachother and form a single VPN.
160 Traditionally VPNs are created by making tunnels, which only have two endpoints.
161 Larger VPNs with more sites are created by adding more tunnels.
162 Tinc takes another approach: only endpoints are specified,
163 the software itself will take care of creating the tunnels.
164 This allows for easier configuration and improved scalability.
166 A lot can---and will be---changed. We have a number of things that we would like to
167 see in the future releases of tinc. Not everything will be available in
168 the near future. Our first objective is to make tinc work perfectly as
169 it stands, and then add more advanced features.
171 Meanwhile, we're always open-minded towards new ideas. And we're
175 @c ==================================================================
176 @node Supported platforms
177 @section Supported platforms
180 Tinc has been verified to work under Linux, FreeBSD, OpenBSD, NetBSD, MacOS/X (Darwin), Solaris, and Windows (both natively and in a Cygwin environment),
181 with various hardware architectures. These are some of the platforms
182 that are supported by the universal tun/tap device driver or other virtual network device drivers.
183 Without such a driver, tinc will most
184 likely compile and run, but it will not be able to send or receive data
188 For an up to date list of supported platforms, please check the list on
190 @uref{http://www.tinc-vpn.org/platforms}.
198 @c Preparing your system
205 @c ==================================================================
207 @chapter Preparations
209 This chapter contains information on how to prepare your system to
213 * Configuring the kernel::
218 @c ==================================================================
219 @node Configuring the kernel
220 @section Configuring the kernel
223 * Configuration of Linux kernels::
224 * Configuration of FreeBSD kernels::
225 * Configuration of OpenBSD kernels::
226 * Configuration of NetBSD kernels::
227 * Configuration of Solaris kernels::
228 * Configuration of Darwin (MacOS/X) kernels::
229 * Configuration of Windows::
233 @c ==================================================================
234 @node Configuration of Linux kernels
235 @subsection Configuration of Linux kernels
237 @cindex Universal tun/tap
238 For tinc to work, you need a kernel that supports the Universal tun/tap device.
239 Most distributions come with kernels that already support this.
240 Here are the options you have to turn on when configuring a new kernel:
243 Code maturity level options
244 [*] Prompt for development and/or incomplete code/drivers
245 Network device support
246 <M> Universal tun/tap device driver support
249 It's not necessary to compile this driver as a module, even if you are going to
250 run more than one instance of tinc.
252 If you decide to build the tun/tap driver as a kernel module, add these lines
253 to @file{/etc/modules.conf}:
256 alias char-major-10-200 tun
260 @c ==================================================================
261 @node Configuration of FreeBSD kernels
262 @subsection Configuration of FreeBSD kernels
264 For FreeBSD version 4.1 and higher, tun and tap drivers are included in the default kernel configuration.
265 The tap driver can be loaded with @code{kldload if_tap}, or by adding @code{if_tap_load="YES"} to @file{/boot/loader.conf}.
268 @c ==================================================================
269 @node Configuration of OpenBSD kernels
270 @subsection Configuration of OpenBSD kernels
272 For OpenBSD version 2.9 and higher,
273 the tun driver is included in the default kernel configuration.
274 There is also a kernel patch from @uref{http://diehard.n-r-g.com/stuff/openbsd/}
275 which adds a tap device to OpenBSD which should work with tinc,
276 but with recent versions of OpenBSD,
277 a tun device can act as a tap device by setting the link0 option with ifconfig.
280 @c ==================================================================
281 @node Configuration of NetBSD kernels
282 @subsection Configuration of NetBSD kernels
284 For NetBSD version 1.5.2 and higher,
285 the tun driver is included in the default kernel configuration.
287 Tunneling IPv6 may not work on NetBSD's tun device.
290 @c ==================================================================
291 @node Configuration of Solaris kernels
292 @subsection Configuration of Solaris kernels
294 For Solaris 8 (SunOS 5.8) and higher,
295 the tun driver may or may not be included in the default kernel configuration.
296 If it isn't, the source can be downloaded from @uref{http://vtun.sourceforge.net/tun/}.
297 For x86 and sparc64 architectures, precompiled versions can be found at @uref{http://www.monkey.org/~dugsong/fragroute/}.
298 If the @file{net/if_tun.h} header file is missing, install it from the source package.
301 @c ==================================================================
302 @node Configuration of Darwin (MacOS/X) kernels
303 @subsection Configuration of Darwin (MacOS/X) kernels
305 Tinc on Darwin relies on a tunnel driver for its data acquisition from the kernel.
306 Tinc supports either the driver from @uref{http://tuntaposx.sourceforge.net/},
307 which supports both tun and tap style devices,
308 and also the driver from from @uref{http://chrisp.de/en/projects/tunnel.html}.
309 The former driver is recommended.
310 The tunnel driver must be loaded before starting tinc with the following command:
317 @c ==================================================================
318 @node Configuration of Windows
319 @subsection Configuration of Windows
321 You will need to install the latest TAP-Win32 driver from OpenVPN.
322 You can download it from @uref{http://openvpn.sourceforge.net}.
323 Using the Network Connections control panel,
324 configure the TAP-Win32 network interface in the same way as you would do from the tinc-up script,
325 as explained in the rest of the documentation.
328 @c ==================================================================
334 Before you can configure or build tinc, you need to have the OpenSSL,
335 zlib and lzo libraries installed on your system. If you try to configure tinc without
336 having them installed, configure will give you an error message, and stop.
346 @c ==================================================================
351 For all cryptography-related functions, tinc uses the functions provided
352 by the OpenSSL library.
354 If this library is not installed, you wil get an error when configuring
355 tinc for build. Support for running tinc without having OpenSSL
356 installed @emph{may} be added in the future.
358 You can use your operating system's package manager to install this if
359 available. Make sure you install the development AND runtime versions
362 If you have to install OpenSSL manually, you can get the source code
363 from @url{http://www.openssl.org/}. Instructions on how to configure,
364 build and install this package are included within the package. Please
365 make sure you build development and runtime libraries (which is the
368 If you installed the OpenSSL libraries from source, it may be necessary
369 to let configure know where they are, by passing configure one of the
370 --with-openssl-* parameters.
373 --with-openssl=DIR OpenSSL library and headers prefix
374 --with-openssl-include=DIR OpenSSL headers directory
375 (Default is OPENSSL_DIR/include)
376 --with-openssl-lib=DIR 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 wil get an error when configuring
419 tinc for build. Support for running tinc without having zlib
420 installed @emph{may} be added in the future.
422 You can use your operating system's package manager to install this if
423 available. Make sure you install the development AND runtime versions
426 If you have to install zlib manually, you can get the source code
427 from @url{http://www.gzip.org/zlib/}. Instructions on how to configure,
428 build and install this package are included within the package. Please
429 make sure you build development and runtime libraries (which is the
433 @c ==================================================================
438 Another form of compression is offered using the lzo library.
440 If this library is not installed, you wil get an error when configuring
441 tinc for build. Support for running tinc without having lzo
442 installed @emph{may} be added in the future.
444 You can use your operating system's package manager to install this if
445 available. Make sure you install the development AND runtime versions
448 If you have to install lzo manually, you can get the source code
449 from @url{http://www.oberhumer.com/opensource/lzo/}. Instructions on how to configure,
450 build and install this package are included within the package. Please
451 make sure you build development and runtime libraries (which is the
455 @c ==================================================================
460 For the main event loop, tinc uses the libevent library.
462 If this library is not installed, you wil get an error when configuring
465 You can use your operating system's package manager to install this if
466 available. Make sure you install the development AND runtime versions
469 If you have to install libevent manually, you can get the source code
470 from @url{http://monkey.org/~provos/libevent/}. Instructions on how to configure,
471 build and install this package are included within the package. Please
472 make sure you build development and runtime libraries (which is the
485 @c ==================================================================
487 @chapter Installation
489 If you use Debian, you may want to install one of the
490 precompiled packages for your system. These packages are equipped with
491 system startup scripts and sample configurations.
493 If you cannot use one of the precompiled packages, or you want to compile tinc
494 for yourself, you can use the source. The source is distributed under
495 the GNU General Public License (GPL). Download the source from the
496 @uref{http://www.tinc-vpn.org/download, download page}, which has
497 the checksums of these files listed; you may wish to check these with
498 md5sum before continuing.
500 Tinc comes in a convenient autoconf/automake package, which you can just
501 treat the same as any other package. Which is just untar it, type
502 `./configure' and then `make'.
503 More detailed instructions are in the file @file{INSTALL}, which is
504 included in the source distribution.
507 * Building and installing tinc::
512 @c ==================================================================
513 @node Building and installing tinc
514 @section Building and installing tinc
516 Detailed instructions on configuring the source, building tinc and installing tinc
517 can be found in the file called @file{INSTALL}.
519 @cindex binary package
520 If you happen to have a binary package for tinc for your distribution,
521 you can use the package management tools of that distribution to install tinc.
522 The documentation that comes along with your distribution will tell you how to do that.
525 * Darwin (MacOS/X) build environment::
526 * Cygwin (Windows) build environment::
527 * MinGW (Windows) build environment::
531 @c ==================================================================
532 @node Darwin (MacOS/X) build environment
533 @subsection Darwin (MacOS/X) build environment
535 In order to build tinc on Darwin, you need to install the MacOS/X Developer Tools
536 from @uref{http://developer.apple.com/tools/macosxtools.html} and
537 a recent version of Fink from @uref{http://fink.sourceforge.net/}.
539 After installation use fink to download and install the following packages:
540 autoconf25, automake, dlcompat, m4, openssl, zlib and lzo.
542 @c ==================================================================
543 @node Cygwin (Windows) build environment
544 @subsection Cygwin (Windows) build environment
546 If Cygwin hasn't already been installed, install it directly from
547 @uref{http://www.cygwin.com/}.
549 When tinc is compiled in a Cygwin environment, it can only be run in this environment,
550 but all programs, including those started outside the Cygwin environment, will be able to use the VPN.
551 It will also support all features.
553 @c ==================================================================
554 @node MinGW (Windows) build environment
555 @subsection MinGW (Windows) build environment
557 You will need to install the MinGW environment from @uref{http://www.mingw.org}.
559 When tinc is compiled using MinGW it runs natively under Windows,
560 it is not necessary to keep MinGW installed.
562 When detaching, tinc will install itself as a service,
563 which will be restarted automatically after reboots.
566 @c ==================================================================
568 @section System files
570 Before you can run tinc, you must make sure you have all the needed
571 files on your system.
579 @c ==================================================================
581 @subsection Device files
584 Most operating systems nowadays come with the necessary device files by default,
585 or they have a mechanism to create them on demand.
587 If you use Linux and do not have udev installed,
588 you may need to create the following device file if it does not exist:
591 mknod -m 600 /dev/net/tun c 10 200
595 @c ==================================================================
597 @subsection Other files
599 @subsubheading @file{/etc/networks}
601 You may add a line to @file{/etc/networks} so that your VPN will get a
602 symbolic name. For example:
608 @subsubheading @file{/etc/services}
611 You may add this line to @file{/etc/services}. The effect is that you
612 may supply a @samp{tinc} as a valid port number to some programs. The
613 number 655 is registered with the IANA.
618 # Ivo Timmermans <ivo@@tinc-vpn.org>
633 @c ==================================================================
635 @chapter Configuration
638 * Configuration introduction::
639 * Multiple networks::
640 * How connections work::
641 * Configuration files::
642 * Generating keypairs::
643 * Network interfaces::
644 * Example configuration::
647 @c ==================================================================
648 @node Configuration introduction
649 @section Configuration introduction
651 Before actually starting to configure tinc and editing files,
652 make sure you have read this entire section so you know what to expect.
653 Then, make it clear to yourself how you want to organize your VPN:
654 What are the nodes (computers running tinc)?
655 What IP addresses/subnets do they have?
656 What is the network mask of the entire VPN?
657 Do you need special firewall rules?
658 Do you have to set up masquerading or forwarding rules?
659 Do you want to run tinc in router mode or switch mode?
660 These questions can only be answered by yourself,
661 you will not find the answers in this documentation.
662 Make sure you have an adequate understanding of networks in general.
663 @cindex Network Administrators Guide
664 A good resource on networking is the
665 @uref{http://www.linuxdoc.org/LDP/nag2/, Linux Network Administrators Guide}.
667 If you have everything clearly pictured in your mind,
668 proceed in the following order:
669 First, generate the configuration files (@file{tinc.conf}, your host configuration file, @file{tinc-up} and perhaps @file{tinc-down}).
670 Then generate the keypairs.
671 Finally, distribute the host configuration files.
672 These steps are described in the subsections below.
675 @c ==================================================================
676 @node Multiple networks
677 @section Multiple networks
679 @cindex multiple networks
681 In order to allow you to run more than one tinc daemon on one computer,
682 for instance if your computer is part of more than one VPN,
683 you can assign a @var{netname} to your VPN.
684 It is not required if you only run one tinc daemon,
685 it doesn't even have to be the same on all the sites of your VPN,
686 but it is recommended that you choose one anyway.
688 We will asume you use a netname throughout this document.
689 This means that you call tincd with the -n argument,
690 which will assign a netname to this daemon.
692 The effect of this is that the daemon will set its configuration
693 root to @file{@value{sysconfdir}/tinc/@var{netname}/}, where @var{netname} is your argument to the -n
694 option. You'll notice that it appears in syslog as @file{tinc.@var{netname}}.
696 However, it is not strictly necessary that you call tinc with the -n
697 option. In this case, the network name would just be empty, and it will
698 be used as such. tinc now looks for files in @file{@value{sysconfdir}/tinc/}, instead of
699 @file{@value{sysconfdir}/tinc/@var{netname}/}; the configuration file should be @file{@value{sysconfdir}/tinc/tinc.conf},
700 and the host configuration files are now expected to be in @file{@value{sysconfdir}/tinc/hosts/}.
702 But it is highly recommended that you use this feature of tinc, because
703 it will be so much clearer whom your daemon talks to. Hence, we will
704 assume that you use it.
707 @c ==================================================================
708 @node How connections work
709 @section How connections work
711 When tinc starts up, it parses the command-line options and then
712 reads in the configuration file tinc.conf.
713 If it sees one or more `ConnectTo' values pointing to other tinc daemons in that file,
714 it will try to connect to those other daemons.
715 Whether this succeeds or not and whether `ConnectTo' is specified or not,
716 tinc will listen for incoming connection from other deamons.
717 If you did specify a `ConnectTo' value and the other side is not responding,
718 tinc will keep retrying.
719 This means that once started, tinc will stay running until you tell it to stop,
720 and failures to connect to other tinc daemons will not stop your tinc daemon
721 for trying again later.
722 This means you don't have to intervene if there are temporary network problems.
726 There is no real distinction between a server and a client in tinc.
727 If you wish, you can view a tinc daemon without a `ConnectTo' value as a server,
728 and one which does specify such a value as a client.
729 It does not matter if two tinc daemons have a `ConnectTo' value pointing to each other however.
732 @c ==================================================================
733 @node Configuration files
734 @section Configuration files
736 The actual configuration of the daemon is done in the file
737 @file{@value{sysconfdir}/tinc/@var{netname}/tinc.conf} and at least one other file in the directory
738 @file{@value{sysconfdir}/tinc/@var{netname}/hosts/}.
740 These file consists of comments (lines started with a #) or assignments
747 The variable names are case insensitive, and any spaces, tabs, newlines
748 and carriage returns are ignored. Note: it is not required that you put
749 in the `=' sign, but doing so improves readability. If you leave it
750 out, remember to replace it with at least one space character.
752 The server configuration is complemented with host specific configuration (see
753 the next section). Although all host configuration options for the local node
754 listed in this document can also be put in
755 @file{@value{sysconfdir}/tinc/@var{netname}/tinc.conf}, it is recommended to
756 put host specific configuration options in the host configuration file, as this
757 makes it easy to exchange with other nodes.
759 In this section all valid variables are listed in alphabetical order.
760 The default value is given between parentheses,
761 other comments are between square brackets.
764 * Main configuration variables::
765 * Host configuration variables::
771 @c ==================================================================
772 @node Main configuration variables
773 @subsection Main configuration variables
776 @cindex AddressFamily
777 @item AddressFamily = <ipv4|ipv6|any> (any)
778 This option affects the address family of listening and outgoing sockets.
779 If any is selected, then depending on the operating system
780 both IPv4 and IPv6 or just IPv6 listening sockets will be created.
782 @cindex BindToAddress
783 @item BindToAddress = <@var{address}> [<@var{port}>] [experimental]
784 If your computer has more than one IPv4 or IPv6 address, tinc
785 will by default listen on all of them for incoming connections.
786 Multiple BindToAddress variables may be specified,
787 in which case listening sockets for each specified address are made.
789 If no @var{port} is specified, the socket will be bound to the port specified by the Port option,
790 or to port 655 if neither is given.
791 To only bind to a specific port but not to a specific address, use "*" for the @var{address}.
793 This option may not work on all platforms.
795 @cindex BindToInterface
796 @item BindToInterface = <@var{interface}> [experimental]
797 If you have more than one network interface in your computer, tinc will
798 by default listen on all of them for incoming connections. It is
799 possible to bind tinc to a single interface like eth0 or ppp0 with this
802 This option may not work on all platforms.
805 @item Broadcast = <no | mst | direct> (mst) [experimental]
806 This option selects the way broadcast packets are sent to other daemons.
807 @emph{NOTE: all nodes in a VPN must use the same Broadcast mode, otherwise routing loops can form.}
811 Broadcast packets are never sent to other nodes.
814 Broadcast packets are sent and forwarded via the VPN's Minimum Spanning Tree.
815 This ensures broadcast packets reach all nodes.
818 Broadcast packets are sent directly to all nodes that can be reached directly.
819 Broadcast packets received from other nodes are never forwarded.
820 If the IndirectData option is also set, broadcast packets will only be sent to nodes which we have a meta connection to.
824 @item ConnectTo = <@var{name}>
825 Specifies which other tinc daemon to connect to on startup.
826 Multiple ConnectTo variables may be specified,
827 in which case outgoing connections to each specified tinc daemon are made.
828 The names should be known to this tinc daemon
829 (i.e., there should be a host configuration file for the name on the ConnectTo line).
831 If you don't specify a host with ConnectTo,
832 tinc won't try to connect to other daemons at all,
833 and will instead just listen for incoming connections.
836 @item DecrementTTL = <yes | no> (no) [experimental]
837 When enabled, tinc will decrement the Time To Live field in IPv4 packets, or the Hop Limit field in IPv6 packets,
838 before forwarding a received packet to the virtual network device or to another node,
839 and will drop packets that have a TTL value of zero,
840 in which case it will send an ICMP Time Exceeded packet back.
842 Do not use this option if you use switch mode and want to use IPv6.
845 @item Device = <@var{device}> (@file{/dev/tap0}, @file{/dev/net/tun} or other depending on platform)
846 The virtual network device to use.
847 Tinc will automatically detect what kind of device it is.
848 Note that you can only use one device per daemon.
849 Under Windows, use @var{Interface} instead of @var{Device}.
850 Note that you can only use one device per daemon.
851 See also @ref{Device files}.
854 @item DeviceType = <@var{type}> (platform dependent)
855 The type of the virtual network device.
856 Tinc will normally automatically select the right type of tun/tap interface, and this option should not be used.
857 However, this option can be used to select one of the special interface types, if support for them is compiled in.
862 Use a dummy interface.
863 No packets are ever read or written to a virtual network device.
864 Useful for testing, or when setting up a node that only forwards packets for other nodes.
868 Open a raw socket, and bind it to a pre-existing
869 @var{Interface} (eth0 by default).
870 All packets are read from this interface.
871 Packets received for the local node are written to the raw socket.
872 However, at least on Linux, the operating system does not process IP packets destined for the local host.
876 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}.
877 Packets are read from and written to this multicast socket.
878 This can be used to connect to UML, QEMU or KVM instances listening on the same multicast address.
879 Do NOT connect multiple tinc daemons to the same multicast address, this will very likely cause routing loops.
880 Also note that this can cause decrypted VPN packets to be sent out on a real network if misconfigured.
883 @item uml (not compiled in by default)
884 Create a UNIX socket with the filename specified by
885 @var{Device}, or @file{@value{localstatedir}/run/@var{netname}.umlsocket}
887 Tinc will wait for a User Mode Linux instance to connect to this socket.
890 @item vde (not compiled in by default)
891 Uses the libvdeplug library to connect to a Virtual Distributed Ethernet switch,
892 using the UNIX socket specified by
893 @var{Device}, or @file{@value{localstatedir}/run/vde.ctl}
897 Also, in case tinc does not seem to correctly interpret packets received from the virtual network device,
898 it can be used to change the way packets are interpreted:
901 @item tun (BSD and Linux)
903 Depending on the platform, this can either be with or without an address family header (see below).
906 @item tunnohead (BSD)
907 Set type to tun without an address family header.
908 Tinc will expect packets read from the virtual network device to start with an IP header.
909 On some platforms IPv6 packets cannot be read from or written to the device in this mode.
912 @item tunifhead (BSD)
913 Set type to tun with an address family header.
914 Tinc will expect packets read from the virtual network device
915 to start with a four byte header containing the address family,
916 followed by an IP header.
917 This mode should support both IPv4 and IPv6 packets.
919 @item tap (BSD and Linux)
921 Tinc will expect packets read from the virtual network device
922 to start with an Ethernet header.
926 @item DirectOnly = <yes|no> (no) [experimental]
927 When this option is enabled, packets that cannot be sent directly to the destination node,
928 but which would have to be forwarded by an intermediate node, are dropped instead.
929 When combined with the IndirectData option,
930 packets for nodes for which we do not have a meta connection with are also dropped.
932 @cindex ECDSAPrivateKeyFile
933 @item ECDSAPrivateKeyFile = <@var{path}> (@file{@value{sysconfdir}/tinc/@var{netname}/ecdsa_key.priv})
934 The file in which the private ECDSA key of this tinc daemon resides.
935 This is only used if ExperimentalProtocol is enabled.
937 @cindex ExperimentalProtocol
938 @item ExperimentalProtocol = <yes|no> (no) [experimental]
939 When this option is enabled, experimental protocol enhancements will be used.
940 Ephemeral ECDH will be used for key exchanges,
941 and ECDSA will be used instead of RSA for authentication.
942 When enabled, an ECDSA key must have been generated before with
943 @samp{tincctl generate-ecdsa-keys}.
944 The experimental protocol may change at any time,
945 and there is no guarantee that tinc will run stable when it is used.
948 @item Forwarding = <off|internal|kernel> (internal) [experimental]
949 This option selects the way indirect packets are forwarded.
953 Incoming packets that are not meant for the local node,
954 but which should be forwarded to another node, are dropped.
957 Incoming packets that are meant for another node are forwarded by tinc internally.
959 This is the default mode, and unless you really know you need another forwarding mode, don't change it.
962 Incoming packets are always sent to the TUN/TAP device, even if the packets are not for the local node.
963 This is less efficient, but allows the kernel to apply its routing and firewall rules on them,
964 and can also help debugging.
967 @cindex GraphDumpFile
968 @item GraphDumpFile = <@var{filename}> [experimental]
969 If this option is present,
970 tinc will dump the current network graph to the file @var{filename}
971 every minute, unless there were no changes to the graph.
972 The file is in a format that can be read by graphviz tools.
973 If @var{filename} starts with a pipe symbol |,
974 then the rest of the filename is interpreted as a shell command
975 that is executed, the graph is then sent to stdin.
978 @item Hostnames = <yes|no> (no)
979 This option selects whether IP addresses (both real and on the VPN)
980 should be resolved. Since DNS lookups are blocking, it might affect
981 tinc's efficiency, even stopping the daemon for a few seconds everytime
982 it does a lookup if your DNS server is not responding.
984 This does not affect resolving hostnames to IP addresses from the
988 @item Interface = <@var{interface}>
989 Defines the name of the interface corresponding to the virtual network device.
990 Depending on the operating system and the type of device this may or may not actually set the name of the interface.
991 Under Windows, this variable is used to select which network interface will be used.
992 If you specified a Device, this variable is almost always already correctly set.
994 @cindex LocalDiscovery
995 @item LocalDiscovery = <yes | no> (no) [experimental]
996 When enabled, tinc will try to detect peers that are on the same local network.
997 This will allow direct communication using LAN addresses, even if both peers are behind a NAT
998 and they only ConnectTo a third node outside the NAT,
999 which normally would prevent the peers from learning each other's LAN address.
1001 Currently, local discovery is implemented by sending broadcast packets to the LAN during path MTU discovery.
1002 This feature may not work in all possible situations.
1005 @item Mode = <router|switch|hub> (router)
1006 This option selects the way packets are routed to other daemons.
1012 variables in the host configuration files will be used to form a routing table.
1013 Only unicast packets of routable protocols (IPv4 and IPv6) are supported in this mode.
1015 This is the default mode, and unless you really know you need another mode, don't change it.
1019 In this mode the MAC addresses of the packets on the VPN will be used to
1020 dynamically create a routing table just like an Ethernet switch does.
1021 Unicast, multicast and broadcast packets of every protocol that runs over Ethernet are supported in this mode
1022 at the cost of frequent broadcast ARP requests and routing table updates.
1024 This mode is primarily useful if you want to bridge Ethernet segments.
1028 This mode is almost the same as the switch mode, but instead
1029 every packet will be broadcast to the other daemons
1030 while no routing table is managed.
1034 @item KeyExpire = <@var{seconds}> (3600)
1035 This option controls the time the encryption keys used to encrypt the data
1036 are valid. It is common practice to change keys at regular intervals to
1037 make it even harder for crackers, even though it is thought to be nearly
1038 impossible to crack a single key.
1041 @item MACExpire = <@var{seconds}> (600)
1042 This option controls the amount of time MAC addresses are kept before they are removed.
1043 This only has effect when Mode is set to "switch".
1046 @item Name = <@var{name}> [required]
1047 This is a symbolic name for this connection.
1048 The name should consist only of alfanumeric and underscore characters (a-z, A-Z, 0-9 and _).
1050 If Name starts with a $, then the contents of the environment variable that follows will be used.
1051 In that case, invalid characters will be converted to underscores.
1052 If Name is $HOST, but no such environment variable exist,
1053 the hostname will be read using the gethostnname() system call.
1055 @cindex PingInterval
1056 @item PingInterval = <@var{seconds}> (60)
1057 The number of seconds of inactivity that tinc will wait before sending a
1058 probe to the other end.
1061 @item PingTimeout = <@var{seconds}> (5)
1062 The number of seconds to wait for a response to pings or to allow meta
1063 connections to block. If the other end doesn't respond within this time,
1064 the connection is terminated, and the others will be notified of this.
1066 @cindex PriorityInheritance
1067 @item PriorityInheritance = <yes|no> (no) [experimental]
1068 When this option is enabled the value of the TOS field of tunneled IPv4 packets
1069 will be inherited by the UDP packets that are sent out.
1072 @item PrivateKey = <@var{key}> [obsolete]
1073 This is the RSA private key for tinc. However, for safety reasons it is
1074 advised to store private keys of any kind in separate files. This prevents
1075 accidental eavesdropping if you are editting the configuration file.
1077 @cindex PrivateKeyFile
1078 @item PrivateKeyFile = <@var{path}> (@file{@value{sysconfdir}/tinc/@var{netname}/rsa_key.priv})
1079 This is the full path name of the RSA private key file that was
1080 generated by @samp{tincctl generate-keys}. It must be a full path, not a
1083 Note that there must be exactly one of PrivateKey
1085 specified in the configuration file.
1087 @cindex ProcessPriority
1088 @item ProcessPriority = <low|normal|high>
1089 When this option is used the priority of the tincd process will be adjusted.
1090 Increasing the priority may help to reduce latency and packet loss on the VPN.
1093 @item Proxy = socks4 | socks4 | http | exec @var{...} [experimental]
1094 Use a proxy when making outgoing connections.
1095 The following proxy types are currently supported:
1099 @item socks4 <@var{address}> <@var{port}> [<@var{username}>]
1100 Connects to the proxy using the SOCKS version 4 protocol.
1101 Optionally, a @var{username} can be supplied which will be passed on to the proxy server.
1104 @item socks4 <@var{address}> <@var{port}> [<@var{username}> <@var{password}>]
1105 Connect to the proxy using the SOCKS version 5 protocol.
1106 If a @var{username} and @var{password} are given, basic username/password authentication will be used,
1107 otherwise no authentication will be used.
1110 @item http <@var{address}> <@var{port}>
1111 Connects to the proxy and sends a HTTP CONNECT request.
1114 @item exec <@var{command}>
1115 Executes the given command which should set up the outgoing connection.
1116 The environment variables @env{NAME}, @env{NODE}, @env{REMOTEADDRES} and @env{REMOTEPORT} are available.
1119 @cindex ReplayWindow
1120 @item ReplayWindow = <bytes> (16)
1121 This is the size of the replay tracking window for each remote node, in bytes.
1122 The window is a bitfield which tracks 1 packet per bit, so for example
1123 the default setting of 16 will track up to 128 packets in the window. In high
1124 bandwidth scenarios, setting this to a higher value can reduce packet loss from
1125 the interaction of replay tracking with underlying real packet loss and/or
1126 reordering. Setting this to zero will disable replay tracking completely and
1127 pass all traffic, but leaves tinc vulnerable to replay-based attacks on your
1131 @cindex StrictSubnets
1132 @item StrictSubnets <yes|no> (no) [experimental]
1133 When this option is enabled tinc will only use Subnet statements which are
1134 present in the host config files in the local
1135 @file{@value{sysconfdir}/tinc/@var{netname}/hosts/} directory.
1137 @cindex TunnelServer
1138 @item TunnelServer = <yes|no> (no) [experimental]
1139 When this option is enabled tinc will no longer forward information between other tinc daemons,
1140 and will only allow connections with nodes for which host config files are present in the local
1141 @file{@value{sysconfdir}/tinc/@var{netname}/hosts/} directory.
1142 Setting this options also implicitly sets StrictSubnets.
1145 @item UDPRcvBuf = <bytes> (OS default)
1146 Sets the socket receive buffer size for the UDP socket, in bytes.
1147 If unset, the default buffer size will be used by the operating system.
1150 @item UDPSndBuf = <bytes> Pq OS default
1151 Sets the socket send buffer size for the UDP socket, in bytes.
1152 If unset, the default buffer size will be used by the operating system.
1157 @c ==================================================================
1158 @node Host configuration variables
1159 @subsection Host configuration variables
1163 @item Address = <@var{IP address}|@var{hostname}> [<port>] [recommended]
1164 This variable is only required if you want to connect to this host. It
1165 must resolve to the external IP address where the host can be reached,
1166 not the one that is internal to the VPN.
1167 If no port is specified, the default Port is used.
1170 @item Cipher = <@var{cipher}> (blowfish)
1171 The symmetric cipher algorithm used to encrypt UDP packets.
1172 Any cipher supported by OpenSSL is recognized.
1173 Furthermore, specifying "none" will turn off packet encryption.
1174 It is best to use only those ciphers which support CBC mode.
1177 @item ClampMSS = <yes|no> (yes)
1178 This option specifies whether tinc should clamp the maximum segment size (MSS)
1179 of TCP packets to the path MTU. This helps in situations where ICMP
1180 Fragmentation Needed or Packet too Big messages are dropped by firewalls.
1183 @item Compression = <@var{level}> (0)
1184 This option sets the level of compression used for UDP packets.
1185 Possible values are 0 (off), 1 (fast zlib) and any integer up to 9 (best zlib),
1186 10 (fast lzo) and 11 (best lzo).
1189 @item Digest = <@var{digest}> (sha1)
1190 The digest algorithm used to authenticate UDP packets.
1191 Any digest supported by OpenSSL is recognized.
1192 Furthermore, specifying "none" will turn off packet authentication.
1194 @cindex IndirectData
1195 @item IndirectData = <yes|no> (no)
1196 This option specifies whether other tinc daemons besides the one you
1197 specified with ConnectTo can make a direct connection to you. This is
1198 especially useful if you are behind a firewall and it is impossible to
1199 make a connection from the outside to your tinc daemon. Otherwise, it
1200 is best to leave this option out or set it to no.
1203 @item MACLength = <@var{bytes}> (4)
1204 The length of the message authentication code used to authenticate UDP packets.
1205 Can be anything from 0
1206 up to the length of the digest produced by the digest algorithm.
1209 @item PMTU = <@var{mtu}> (1514)
1210 This option controls the initial path MTU to this node.
1212 @cindex PMTUDiscovery
1213 @item PMTUDiscovery = <yes|no> (yes)
1214 When this option is enabled, tinc will try to discover the path MTU to this node.
1215 After the path MTU has been discovered, it will be enforced on the VPN.
1218 @item Port = <@var{port}> (655)
1219 This is the port this tinc daemon listens on.
1220 You can use decimal portnumbers or symbolic names (as listed in @file{/etc/services}).
1223 @item PublicKey = <@var{key}> [obsolete]
1224 This is the RSA public key for this host.
1226 @cindex PublicKeyFile
1227 @item PublicKeyFile = <@var{path}> [obsolete]
1228 This is the full path name of the RSA public key file that was generated
1229 by @samp{tincctl generate-keys}. It must be a full path, not a relative
1233 From version 1.0pre4 on tinc will store the public key directly into the
1234 host configuration file in PEM format, the above two options then are not
1235 necessary. Either the PEM format is used, or exactly
1236 @strong{one of the above two options} must be specified
1237 in each host configuration file, if you want to be able to establish a
1238 connection with that host.
1241 @item Subnet = <@var{address}[/@var{prefixlength}[#@var{weight}]]>
1242 The subnet which this tinc daemon will serve.
1243 Tinc tries to look up which other daemon it should send a packet to by searching the appropiate subnet.
1244 If the packet matches a subnet,
1245 it will be sent to the daemon who has this subnet in his host configuration file.
1246 Multiple subnet lines can be specified for each daemon.
1248 Subnets can either be single MAC, IPv4 or IPv6 addresses,
1249 in which case a subnet consisting of only that single address is assumed,
1250 or they can be a IPv4 or IPv6 network address with a prefixlength.
1251 For example, IPv4 subnets must be in a form like 192.168.1.0/24,
1252 where 192.168.1.0 is the network address and 24 is the number of bits set in the netmask.
1253 Note that subnets like 192.168.1.1/24 are invalid!
1254 Read a networking HOWTO/FAQ/guide if you don't understand this.
1255 IPv6 subnets are notated like fec0:0:0:1::/64.
1256 MAC addresses are notated like 0:1a:2b:3c:4d:5e.
1258 @cindex CIDR notation
1259 Prefixlength is the number of bits set to 1 in the netmask part; for
1260 example: netmask 255.255.255.0 would become /24, 255.255.252.0 becomes
1261 /22. This conforms to standard CIDR notation as described in
1262 @uref{ftp://ftp.isi.edu/in-notes/rfc1519.txt, RFC1519}
1264 A Subnet can be given a weight to indicate its priority over identical Subnets
1265 owned by different nodes. The default weight is 10. Lower values indicate
1266 higher priority. Packets will be sent to the node with the highest priority,
1267 unless that node is not reachable, in which case the node with the next highest
1268 priority will be tried, and so on.
1271 @item TCPonly = <yes|no> (no)
1272 If this variable is set to yes, then the packets are tunnelled over a
1273 TCP connection instead of a UDP connection. This is especially useful
1274 for those who want to run a tinc daemon from behind a masquerading
1275 firewall, or if UDP packet routing is disabled somehow.
1276 Setting this options also implicitly sets IndirectData.
1280 @c ==================================================================
1285 Apart from reading the server and host configuration files,
1286 tinc can also run scripts at certain moments.
1287 Under Windows (not Cygwin), the scripts should have the extension .bat.
1291 @item @value{sysconfdir}/tinc/@var{netname}/tinc-up
1292 This is the most important script.
1293 If it is present it will be executed right after the tinc daemon has been
1294 started and has connected to the virtual network device.
1295 It should be used to set up the corresponding network interface,
1296 but can also be used to start other things.
1297 Under Windows you can use the Network Connections control panel instead of creating this script.
1300 @item @value{sysconfdir}/tinc/@var{netname}/tinc-down
1301 This script is started right before the tinc daemon quits.
1303 @item @value{sysconfdir}/tinc/@var{netname}/hosts/@var{host}-up
1304 This script is started when the tinc daemon with name @var{host} becomes reachable.
1306 @item @value{sysconfdir}/tinc/@var{netname}/hosts/@var{host}-down
1307 This script is started when the tinc daemon with name @var{host} becomes unreachable.
1309 @item @value{sysconfdir}/tinc/@var{netname}/host-up
1310 This script is started when any host becomes reachable.
1312 @item @value{sysconfdir}/tinc/@var{netname}/host-down
1313 This script is started when any host becomes unreachable.
1315 @item @value{sysconfdir}/tinc/@var{netname}/subnet-up
1316 This script is started when a Subnet becomes reachable.
1317 The Subnet and the node it belongs to are passed in environment variables.
1319 @item @value{sysconfdir}/tinc/@var{netname}/subnet-down
1320 This script is started when a Subnet becomes unreachable.
1323 @cindex environment variables
1324 The scripts are started without command line arguments,
1325 but can make use of certain environment variables.
1326 Under UNIX like operating systems the names of environment variables must be preceded by a $ in scripts.
1327 Under Windows, in @file{.bat} files, they have to be put between % signs.
1332 If a netname was specified, this environment variable contains it.
1336 Contains the name of this tinc daemon.
1340 Contains the name of the virtual network device that tinc uses.
1344 Contains the name of the virtual network interface that tinc uses.
1345 This should be used for commands like ifconfig.
1349 When a host becomes (un)reachable, this is set to its name.
1350 If a subnet becomes (un)reachable, this is set to the owner of that subnet.
1352 @cindex REMOTEADDRESS
1354 When a host becomes (un)reachable, this is set to its real address.
1358 When a host becomes (un)reachable,
1359 this is set to the port number it uses for communication with other tinc daemons.
1363 When a subnet becomes (un)reachable, this is set to the subnet.
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 configuarion 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 tincctl -n @var{netname} generate-keys
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:
1640 tincctl -n company generate-keys
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 -n, --net=@var{netname}
1707 Use configuration for net @var{netname}.
1708 This will let tinc read all configuration files from
1709 @file{@value{sysconfdir}/tinc/@var{netname}/}.
1710 Specifying . for @var{netname} is the same as not specifying any @var{netname}.
1711 @xref{Multiple networks}.
1713 @item --pidfile=@var{filename}
1714 Store a cookie in @var{filename} which allows tincctl to authenticate.
1715 If unspecified, the default is
1716 @file{@value{localstatedir}/run/tinc.@var{netname}.pid}.
1718 @item -o, --option=[@var{HOST}.]@var{KEY}=@var{VALUE}
1719 Without specifying a @var{HOST}, this will set server configuration variable @var{KEY} to @var{VALUE}.
1720 If specified as @var{HOST}.@var{KEY}=@var{VALUE},
1721 this will set the host configuration variable @var{KEY} of the host named @var{HOST} to @var{VALUE}.
1722 This option can be used more than once to specify multiple configuration variables.
1725 Lock tinc into main memory.
1726 This will prevent sensitive data like shared private keys to be written to the system swap files/partitions.
1728 @item --logfile[=@var{file}]
1729 Write log entries to a file instead of to the system logging facility.
1730 If @var{file} is omitted, the default is @file{@value{localstatedir}/log/tinc.@var{netname}.log}.
1732 @item --bypass-security
1733 Disables encryption and authentication.
1734 Only useful for debugging.
1737 Change process root directory to the directory where the config file is
1738 located (@file{@value{sysconfdir}/tinc/@var{netname}/} as determined by
1739 -n/--net option or as given by -c/--config option), for added security.
1740 The chroot is performed after all the initialization is done, after
1741 writing pid files and opening network sockets.
1743 Note that this option alone does not do any good without -U/--user, below.
1745 Note also that tinc can't run scripts anymore (such as tinc-down or host-up),
1746 unless it's setup to be runnable inside chroot environment.
1748 @item -U, --user=@var{user}
1749 Switch to the given @var{user} after initialization, at the same time as
1750 chroot is performed (see --chroot above). With this option tinc drops
1751 privileges, for added security.
1754 Display a short reminder of these runtime options and terminate.
1757 Output version information and exit.
1761 @c ==================================================================
1766 You can also send the following signals to a running tincd process:
1772 Forces tinc to try to connect to all uplinks immediately.
1773 Usually tinc attempts to do this itself,
1774 but increases the time it waits between the attempts each time it failed,
1775 and if tinc didn't succeed to connect to an uplink the first time after it started,
1776 it defaults to the maximum time of 15 minutes.
1779 Partially rereads configuration files.
1780 Connections to hosts whose host config file are removed are closed.
1781 New outgoing connections specified in @file{tinc.conf} will be made.
1782 If the --logfile option is used, this will also close and reopen the log file,
1783 useful when log rotation is used.
1787 @c ==================================================================
1789 @section Debug levels
1791 @cindex debug levels
1792 The tinc daemon can send a lot of messages to the syslog.
1793 The higher the debug level, the more messages it will log.
1794 Each level inherits all messages of the previous level:
1800 This will log a message indicating tinc has started along with a version number.
1801 It will also log any serious error.
1804 This will log all connections that are made with other tinc daemons.
1807 This will log status and error messages from scripts and other tinc daemons.
1810 This will log all requests that are exchanged with other tinc daemons. These include
1811 authentication, key exchange and connection list updates.
1814 This will log a copy of everything received on the meta socket.
1817 This will log all network traffic over the virtual private network.
1821 @c ==================================================================
1822 @node Solving problems
1823 @section Solving problems
1825 If tinc starts without problems, but if the VPN doesn't work, you will have to find the cause of the problem.
1826 The first thing to do is to start tinc with a high debug level in the foreground,
1827 so you can directly see everything tinc logs:
1830 tincd -n @var{netname} -d5 -D
1833 If tinc does not log any error messages, then you might want to check the following things:
1836 @item @file{tinc-up} script
1837 Does this script contain the right commands?
1838 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.
1841 Does the Subnet (or Subnets) in the host configuration file of this host match the portion of the VPN that belongs to this host?
1843 @item Firewalls and NATs
1844 Do you have a firewall or a NAT device (a masquerading firewall or perhaps an ADSL router that performs masquerading)?
1845 If so, check that it allows TCP and UDP traffic on port 655.
1846 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.
1847 You can add @samp{TCPOnly = yes} to your host config file to force tinc to only use a single TCP connection,
1848 this works through most firewalls and NATs.
1853 @c ==================================================================
1854 @node Error messages
1855 @section Error messages
1857 What follows is a list of the most common error messages you might find in the logs.
1858 Some of them will only be visible if the debug level is high enough.
1861 @item Could not open /dev/tap0: No such device
1864 @item You forgot to `modprobe netlink_dev' or `modprobe ethertap'.
1865 @item You forgot to compile `Netlink device emulation' in the kernel.
1868 @item Can't write to /dev/net/tun: No such device
1871 @item You forgot to `modprobe tun'.
1872 @item You forgot to compile `Universal TUN/TAP driver' in the kernel.
1873 @item The tun device is located somewhere else in @file{/dev/}.
1876 @item Network address and prefix length do not match!
1879 @item The Subnet field must contain a @emph{network} address, trailing bits should be 0.
1880 @item If you only want to use one IP address, set the netmask to /32.
1883 @item Error reading RSA key file `rsa_key.priv': No such file or directory
1886 @item You forgot to create a public/private keypair.
1887 @item Specify the complete pathname to the private key file with the @samp{PrivateKeyFile} option.
1890 @item Warning: insecure file permissions for RSA private key file `rsa_key.priv'!
1893 @item The private key file is readable by users other than root.
1894 Use chmod to correct the file permissions.
1897 @item Creating metasocket failed: Address family not supported
1900 @item By default tinc tries to create both IPv4 and IPv6 sockets.
1901 On some platforms this might not be implemented.
1902 If the logs show @samp{Ready} later on, then at least one metasocket was created,
1903 and you can ignore this message.
1904 You can add @samp{AddressFamily = ipv4} to @file{tinc.conf} to prevent this from happening.
1907 @item Cannot route packet: unknown IPv4 destination 1.2.3.4
1910 @item You try to send traffic to a host on the VPN for which no Subnet is known.
1911 @item If it is a broadcast address (ending in .255), it probably is a samba server or a Windows host sending broadcast packets.
1915 @item Cannot route packet: ARP request for unknown address 1.2.3.4
1918 @item You try to send traffic to a host on the VPN for which no Subnet is known.
1921 @item Packet with destination 1.2.3.4 is looping back to us!
1924 @item Something is not configured right. Packets are being sent out to the
1925 virtual network device, but according to the Subnet directives in your host configuration
1926 file, those packets should go to your own host. Most common mistake is that
1927 you have a Subnet line in your host configuration file with a prefix length which is
1928 just as large as the prefix of the virtual network interface. The latter should in almost all
1929 cases be larger. Rethink your configuration.
1930 Note that you will only see this message if you specified a debug
1931 level of 5 or higher!
1932 @item Chances are that a @samp{Subnet = ...} line in the host configuration file of this tinc daemon is wrong.
1933 Change it to a subnet that is accepted locally by another interface,
1934 or if that is not the case, try changing the prefix length into /32.
1937 @item Node foo (1.2.3.4) is not reachable
1940 @item Node foo does not have a connection anymore, its tinc daemon is not running or its connection to the Internet is broken.
1943 @item Received UDP packet from unknown source 1.2.3.4 (port 12345)
1946 @item If you see this only sporadically, it is harmless and caused by a node sending packets using an old key.
1947 @item If you see this often and another node is not reachable anymore, then a NAT (masquerading firewall) is changing the source address of UDP packets.
1948 You can add @samp{TCPOnly = yes} to host configuration files to force all VPN traffic to go over a TCP connection.
1951 @item Got bad/bogus/unauthorized REQUEST from foo (1.2.3.4 port 12345)
1954 @item Node foo does not have the right public/private keypair.
1955 Generate new keypairs and distribute them again.
1956 @item An attacker tries to gain access to your VPN.
1957 @item A network error caused corruption of metadata sent from foo.
1962 @c ==================================================================
1963 @node Sending bug reports
1964 @section Sending bug reports
1966 If you really can't find the cause of a problem, or if you suspect tinc is not working right,
1967 you can send us a bugreport, see @ref{Contact information}.
1968 Be sure to include the following information in your bugreport:
1971 @item A clear description of what you are trying to achieve and what the problem is.
1972 @item What platform (operating system, version, hardware architecture) and which version of tinc you use.
1973 @item If compiling tinc fails, a copy of @file{config.log} and the error messages you get.
1974 @item Otherwise, a copy of @file{tinc.conf}, @file{tinc-up} and all files in the @file{hosts/} directory.
1975 @item The output of the commands @samp{ifconfig -a} and @samp{route -n} (or @samp{netstat -rn} if that doesn't work).
1976 @item The output of any command that fails to work as it should (like ping or traceroute).
1979 @c ==================================================================
1980 @node Controlling tinc
1981 @chapter Controlling tinc
1983 You can control and inspect a running tincd through the tincctl
1984 command. A quick example:
1987 tincctl -n @var{netname} reload
1991 * tincctl runtime options::
1992 * tincctl environment variables::
1993 * tincctl commands::
1994 * tincctl examples::
1999 @c ==================================================================
2000 @node tincctl runtime options
2001 @section tincctl runtime options
2005 @item -c, --config=@var{path}
2006 Read configuration options from the directory @var{path}. The default is
2007 @file{@value{sysconfdir}/tinc/@var{netname}/}.
2009 @item -n, --net=@var{netname}
2010 Use configuration for net @var{netname}. @xref{Multiple networks}.
2012 @item --pidfile=@var{filename}
2013 Use the cookie from @var{filename} to authenticate with a running tinc daemon.
2014 If unspecified, the default is
2015 @file{@value{localstatedir}/run/tinc.@var{netname}.pid}.
2018 Display a short reminder of runtime options and commands, then terminate.
2021 Output version information and exit.
2025 @c ==================================================================
2026 @node tincctl environment variables
2027 @section tincctl environment variables
2032 If no netname is specified on the command line with the @option{-n} option,
2033 the value of this environment variable is used.
2036 @c ==================================================================
2037 @node tincctl commands
2038 @section tincctl commands
2043 @item init [@var{name}]
2044 Create initial configuration files and RSA and ECDSA keypairs with default length.
2045 If no @var{name} for this node is given, it will be asked for.
2047 @item config [set] @var{variable} @var{value}
2048 Set configuration variable @var{variable} to the given @var{value}.
2049 All previously existing configuration variables with the same name are removed.
2050 To set a variable for a specific host, use the notation @var{host}.@var{variable}.
2052 @item config add @var{variable} @var{value}
2053 As above, but without removing any previously existing configuration variables.
2055 @item config del @var{variable} [@var{value}]
2056 Remove configuration variables with the same name and @var{value}.
2057 If no @var{value} is given, all configuration variables with the same name will be removed.
2059 @item edit @var{filename}
2060 Start an editor for the given configuration file.
2061 You do not need to specify the full path to the file.
2063 @item start [tincd options]
2064 Start @samp{tincd}, optionally with the given extra options.
2070 Restart @samp{tincd}.
2073 Partially rereads configuration files. Connections to hosts whose host
2074 config files are removed are closed. New outgoing connections specified
2075 in @file{tinc.conf} will be made.
2078 Shows the PID of the currently running @samp{tincd}.
2080 @item generate-keys [@var{bits}]
2081 Generate public/private keypair of @var{bits} length. If @var{bits} is not specified,
2082 1024 is the default. tinc will ask where you want to store the files,
2083 but will default to the configuration directory (you can use the -c or -n
2087 Dump a list of all known nodes in the VPN.
2090 Dump a list of all known connections in the VPN.
2093 Dump a list of all known subnets in the VPN.
2095 @item dump connections
2096 Dump a list of all meta connections with ourself.
2099 Dump a graph of the VPN in dotty format.
2101 @item info @var{node} | @var{subnet} | @var{address}
2102 Show information about a particular @var{node}, @var{subnet} or @var{address}.
2103 If an @var{address} is given, any matching subnet will be shown.
2106 Purges all information remembered about unreachable nodes.
2108 @item debug @var{level}
2109 Sets debug level to @var{level}.
2111 @item log [@var{level}]
2112 Capture log messages from a running tinc daemon.
2113 An optional debug level can be given that will be applied only for log messages sent to tincctl.
2116 Forces tinc to try to connect to all uplinks immediately.
2117 Usually tinc attempts to do this itself,
2118 but increases the time it waits between the attempts each time it failed,
2119 and if tinc didn't succeed to connect to an uplink the first time after it started,
2120 it defaults to the maximum time of 15 minutes.
2122 @item disconnect @var{node}
2123 Closes the meta connection with the given @var{node}.
2126 If tincctl is compiled with libcurses support, this will display live traffic statistics for all the known nodes,
2127 similar to the UNIX top command.
2128 See below for more information.
2131 Dump VPN traffic going through the local tinc node in pcap-savefile format to standard output,
2132 from where it can be redirected to a file or piped through a program that can parse it directly,
2137 @c ==================================================================
2138 @node tincctl examples
2139 @section tincctl examples
2141 Examples of some commands:
2144 tincctl -n vpn dump graph | circo -Txlib
2145 tincctl -n vpn pcap | tcpdump -r -
2149 Example of configuring tinc using tincctl:
2152 tincctl -n vpn init foo
2153 tincctl -n vpn config Subnet 192.168.1.0/24
2154 tincctl -n vpn config bar.Address bar.example.com
2155 tincctl -n vpn config ConnectTo bar
2158 @c ==================================================================
2160 @section tincctl top
2162 The top command connects to a running tinc daemon and repeatedly queries its per-node traffic counters.
2163 It displays a list of all the known nodes in the left-most column,
2164 and the amount of bytes and packets read from and sent to each node in the other columns.
2165 By default, the information is updated every second.
2166 The behaviour of the top command can be changed using the following keys:
2171 Change the interval between updates.
2172 After pressing the @key{s} key, enter the desired interval in seconds, followed by enter.
2173 Fractional seconds are honored.
2174 Intervals lower than 0.1 seconds are not allowed.
2177 Toggle between displaying current traffic rates (in packets and bytes per second)
2178 and cummulative traffic (total packets and bytes since the tinc daemon started).
2181 Sort the list of nodes by name.
2184 Sort the list of nodes by incoming amount of bytes.
2187 Sort the list of nodes by incoming amount of packets.
2190 Sort the list of nodes by outgoing amount of bytes.
2193 Sort the list of nodes by outgoing amount of packets.
2196 Sort the list of nodes by sum of incoming and outgoing amount of bytes.
2199 Sort the list of nodes by sum of incoming and outgoing amount of packets.
2202 Show amount of traffic in bytes.
2205 Show amount of traffic in kilobytes.
2208 Show amount of traffic in megabytes.
2211 Show amount of traffic in gigabytes.
2219 @c ==================================================================
2220 @node Technical information
2221 @chapter Technical information
2226 * The meta-protocol::
2231 @c ==================================================================
2232 @node The connection
2233 @section The connection
2236 Tinc is a daemon that takes VPN data and transmit that to another host
2237 computer over the existing Internet infrastructure.
2241 * The meta-connection::
2245 @c ==================================================================
2246 @node The UDP tunnel
2247 @subsection The UDP tunnel
2249 @cindex virtual network device
2251 The data itself is read from a character device file, the so-called
2252 @emph{virtual network device}. This device is associated with a network
2253 interface. Any data sent to this interface can be read from the device,
2254 and any data written to the device gets sent from the interface.
2255 There are two possible types of virtual network devices:
2256 `tun' style, which are point-to-point devices which can only handle IPv4 and/or IPv6 packets,
2257 and `tap' style, which are Ethernet devices and handle complete Ethernet frames.
2259 So when tinc reads an Ethernet frame from the device, it determines its
2260 type. When tinc is in it's default routing mode, it can handle IPv4 and IPv6
2261 packets. Depending on the Subnet lines, it will send the packets off to their destination IP address.
2262 In the `switch' and `hub' mode, tinc will use broadcasts and MAC address discovery
2263 to deduce the destination of the packets.
2264 Since the latter modes only depend on the link layer information,
2265 any protocol that runs over Ethernet is supported (for instance IPX and Appletalk).
2266 However, only `tap' style devices provide this information.
2268 After the destination has been determined,
2269 the packet will be compressed (optionally),
2270 a sequence number will be added to the packet,
2271 the packet will then be encrypted
2272 and a message authentication code will be appended.
2274 @cindex encapsulating
2276 When that is done, time has come to actually transport the
2277 packet to the destination computer. We do this by sending the packet
2278 over an UDP connection to the destination host. This is called
2279 @emph{encapsulating}, the VPN packet (though now encrypted) is
2280 encapsulated in another IP datagram.
2282 When the destination receives this packet, the same thing happens, only
2283 in reverse. So it checks the message authentication code, decrypts the contents of the UDP datagram,
2284 checks the sequence number
2285 and writes the decrypted information to its own virtual network device.
2287 If the virtual network device is a `tun' device (a point-to-point tunnel),
2288 there is no problem for the kernel to accept a packet.
2289 However, if it is a `tap' device (this is the only available type on FreeBSD),
2290 the destination MAC address must match that of the virtual network interface.
2291 If tinc is in it's default routing mode, ARP does not work, so the correct destination MAC
2292 can not be known by the sending host.
2293 Tinc solves this by letting the receiving end detect the MAC address of its own virtual network interface
2294 and overwriting the destination MAC address of the received packet.
2296 In switch or hub modes ARP does work so the sender already knows the correct destination MAC address.
2297 In those modes every interface should have a unique MAC address, so make sure they are not the same.
2298 Because switch and hub modes rely on MAC addresses to function correctly,
2299 these modes cannot be used on the following operating systems which don't have a `tap' style virtual network device:
2300 OpenBSD, NetBSD, Darwin and Solaris.
2303 @c ==================================================================
2304 @node The meta-connection
2305 @subsection The meta-connection
2307 Having only a UDP connection available is not enough. Though suitable
2308 for transmitting data, we want to be able to reliably send other
2309 information, such as routing and session key information to somebody.
2312 TCP is a better alternative, because it already contains protection
2313 against information being lost, unlike UDP.
2315 So we establish two connections. One for the encrypted VPN data, and one
2316 for other information, the meta-data. Hence, we call the second
2317 connection the meta-connection. We can now be sure that the
2318 meta-information doesn't get lost on the way to another computer.
2320 @cindex data-protocol
2321 @cindex meta-protocol
2322 Like with any communication, we must have a protocol, so that everybody
2323 knows what everything stands for, and how she should react. Because we
2324 have two connections, we also have two protocols. The protocol used for
2325 the UDP data is the ``data-protocol,'' the other one is the
2328 The reason we don't use TCP for both protocols is that UDP is much
2329 better for encapsulation, even while it is less reliable. The real
2330 problem is that when TCP would be used to encapsulate a TCP stream
2331 that's on the private network, for every packet sent there would be
2332 three ACKs sent instead of just one. Furthermore, if there would be
2333 a timeout, both TCP streams would sense the timeout, and both would
2334 start re-sending packets.
2337 @c ==================================================================
2338 @node The meta-protocol
2339 @section The meta-protocol
2341 The meta protocol is used to tie all tinc daemons together, and
2342 exchange information about which tinc daemon serves which virtual
2345 The meta protocol consists of requests that can be sent to the other
2346 side. Each request has a unique number and several parameters. All
2347 requests are represented in the standard ASCII character set. It is
2348 possible to use tools such as telnet or netcat to connect to a tinc
2349 daemon started with the --bypass-security option
2350 and to read and write requests by hand, provided that one
2351 understands the numeric codes sent.
2353 The authentication scheme is described in @ref{Authentication protocol}. After a
2354 successful authentication, the server and the client will exchange all the
2355 information about other tinc daemons and subnets they know of, so that both
2356 sides (and all the other tinc daemons behind them) have their information
2363 ------------------------------------------------------------------
2364 ADD_EDGE node1 node2 21.32.43.54 655 222 0
2365 | | | | | +-> options
2366 | | | | +----> weight
2367 | | | +--------> UDP port of node2
2368 | | +----------------> real address of node2
2369 | +-------------------------> name of destination node
2370 +-------------------------------> name of source node
2372 ADD_SUBNET node 192.168.1.0/24
2373 | | +--> prefixlength
2374 | +--------> network address
2375 +------------------> owner of this subnet
2376 ------------------------------------------------------------------
2379 The ADD_EDGE messages are to inform other tinc daemons that a connection between
2380 two nodes exist. The address of the destination node is available so that
2381 VPN packets can be sent directly to that node.
2383 The ADD_SUBNET messages inform other tinc daemons that certain subnets belong
2384 to certain nodes. tinc will use it to determine to which node a VPN packet has
2391 ------------------------------------------------------------------
2392 DEL_EDGE node1 node2
2393 | +----> name of destination node
2394 +----------> name of source node
2396 DEL_SUBNET node 192.168.1.0/24
2397 | | +--> prefixlength
2398 | +--------> network address
2399 +------------------> owner of this subnet
2400 ------------------------------------------------------------------
2403 In case a connection between two daemons is closed or broken, DEL_EDGE messages
2404 are sent to inform the other daemons of that fact. Each daemon will calculate a
2405 new route to the the daemons, or mark them unreachable if there isn't any.
2412 ------------------------------------------------------------------
2413 REQ_KEY origin destination
2414 | +--> name of the tinc daemon it wants the key from
2415 +----------> name of the daemon that wants the key
2417 ANS_KEY origin destination 4ae0b0a82d6e0078 91 64 4
2418 | | \______________/ | | +--> MAC length
2419 | | | | +-----> digest algorithm
2420 | | | +--------> cipher algorithm
2421 | | +--> 128 bits key
2422 | +--> name of the daemon that wants the key
2423 +----------> name of the daemon that uses this key
2426 +--> daemon that has changed it's packet key
2427 ------------------------------------------------------------------
2430 The keys used to encrypt VPN packets are not sent out directly. This is
2431 because it would generate a lot of traffic on VPNs with many daemons, and
2432 chances are that not every tinc daemon will ever send a packet to every
2433 other daemon. Instead, if a daemon needs a key it sends a request for it
2434 via the meta connection of the nearest hop in the direction of the
2441 ------------------------------------------------------------------
2444 ------------------------------------------------------------------
2447 There is also a mechanism to check if hosts are still alive. Since network
2448 failures or a crash can cause a daemon to be killed without properly
2449 shutting down the TCP connection, this is necessary to keep an up to date
2450 connection list. PINGs are sent at regular intervals, except when there
2451 is also some other traffic. A little bit of salt (random data) is added
2452 with each PING and PONG message, to make sure that long sequences of PING/PONG
2453 messages without any other traffic won't result in known plaintext.
2455 This basically covers what is sent over the meta connection by tinc.
2458 @c ==================================================================
2464 Tinc got its name from ``TINC,'' short for @emph{There Is No Cabal}; the
2465 alleged Cabal was/is an organisation that was said to keep an eye on the
2466 entire Internet. As this is exactly what you @emph{don't} want, we named
2467 the tinc project after TINC.
2470 But in order to be ``immune'' to eavesdropping, you'll have to encrypt
2471 your data. Because tinc is a @emph{Secure} VPN (SVPN) daemon, it does
2472 exactly that: encrypt.
2473 Tinc by default uses blowfish encryption with 128 bit keys in CBC mode, 32 bit
2474 sequence numbers and 4 byte long message authentication codes to make sure
2475 eavesdroppers cannot get and cannot change any information at all from the
2476 packets they can intercept. The encryption algorithm and message authentication
2477 algorithm can be changed in the configuration. The length of the message
2478 authentication codes is also adjustable. The length of the key for the
2479 encryption algorithm is always the default length used by OpenSSL.
2482 * Authentication protocol::
2483 * Encryption of network packets::
2488 @c ==================================================================
2489 @node Authentication protocol
2490 @subsection Authentication protocol
2492 @cindex authentication
2493 A new scheme for authentication in tinc has been devised, which offers some
2494 improvements over the protocol used in 1.0pre2 and 1.0pre3. Explanation is
2504 --------------------------------------------------------------------------
2505 client <attempts connection>
2507 server <accepts connection>
2511 +-------> name of tinc daemon
2515 +-------> name of tinc daemon
2517 client META_KEY 5f0823a93e35b69e...7086ec7866ce582b
2518 \_________________________________/
2519 +-> RSAKEYLEN bits totally random string S1,
2520 encrypted with server's public RSA key
2522 server META_KEY 6ab9c1640388f8f0...45d1a07f8a672630
2523 \_________________________________/
2524 +-> RSAKEYLEN bits totally random string S2,
2525 encrypted with client's public RSA key
2528 - the client will symmetrically encrypt outgoing traffic using S1
2529 - the server will symmetrically encrypt outgoing traffic using S2
2531 client CHALLENGE da02add1817c1920989ba6ae2a49cecbda0
2532 \_________________________________/
2533 +-> CHALLEN bits totally random string H1
2535 server CHALLENGE 57fb4b2ccd70d6bb35a64c142f47e61d57f
2536 \_________________________________/
2537 +-> CHALLEN bits totally random string H2
2539 client CHAL_REPLY 816a86
2540 +-> 160 bits SHA1 of H2
2542 server CHAL_REPLY 928ffe
2543 +-> 160 bits SHA1 of H1
2545 After the correct challenge replies are received, both ends have proved
2546 their identity. Further information is exchanged.
2548 client ACK 655 123 0
2550 | +----> estimated weight
2551 +--------> listening port of client
2553 server ACK 655 321 0
2555 | +----> estimated weight
2556 +--------> listening port of server
2557 --------------------------------------------------------------------------
2560 This new scheme has several improvements, both in efficiency and security.
2562 First of all, the server sends exactly the same kind of messages over the wire
2563 as the client. The previous versions of tinc first authenticated the client,
2564 and then the server. This scheme even allows both sides to send their messages
2565 simultaneously, there is no need to wait for the other to send something first.
2566 This means that any calculations that need to be done upon sending or receiving
2567 a message can also be done in parallel. This is especially important when doing
2568 RSA encryption/decryption. Given that these calculations are the main part of
2569 the CPU time spent for the authentication, speed is improved by a factor 2.
2571 Second, only one RSA encrypted message is sent instead of two. This reduces the
2572 amount of information attackers can see (and thus use for a cryptographic
2573 attack). It also improves speed by a factor two, making the total speedup a
2576 Third, and most important:
2577 The symmetric cipher keys are exchanged first, the challenge is done
2578 afterwards. In the previous authentication scheme, because a man-in-the-middle
2579 could pass the challenge/chal_reply phase (by just copying the messages between
2580 the two real tinc daemons), but no information was exchanged that was really
2581 needed to read the rest of the messages, the challenge/chal_reply phase was of
2582 no real use. The man-in-the-middle was only stopped by the fact that only after
2583 the ACK messages were encrypted with the symmetric cipher. Potentially, it
2584 could even send it's own symmetric key to the server (if it knew the server's
2585 public key) and read some of the metadata the server would send it (it was
2586 impossible for the mitm to read actual network packets though). The new scheme
2587 however prevents this.
2589 This new scheme makes sure that first of all, symmetric keys are exchanged. The
2590 rest of the messages are then encrypted with the symmetric cipher. Then, each
2591 side can only read received messages if they have their private key. The
2592 challenge is there to let the other side know that the private key is really
2593 known, because a challenge reply can only be sent back if the challenge is
2594 decrypted correctly, and that can only be done with knowledge of the private
2597 Fourth: the first thing that is sent via the symmetric cipher encrypted
2598 connection is a totally random string, so that there is no known plaintext (for
2599 an attacker) in the beginning of the encrypted stream.
2602 @c ==================================================================
2603 @node Encryption of network packets
2604 @subsection Encryption of network packets
2607 A data packet can only be sent if the encryption key is known to both
2608 parties, and the connection is activated. If the encryption key is not
2609 known, a request is sent to the destination using the meta connection
2610 to retrieve it. The packet is stored in a queue while waiting for the
2614 The UDP packet containing the network packet from the VPN has the following layout:
2617 ... | IP header | UDP header | seqno | VPN packet | MAC | UDP trailer
2618 \___________________/\_____/
2620 V +---> digest algorithm
2621 Encrypted with symmetric cipher
2624 So, the entire VPN packet is encrypted using a symmetric cipher, including a 32 bits
2625 sequence number that is added in front of the actual VPN packet, to act as a unique
2626 IV for each packet and to prevent replay attacks. A message authentication code
2627 is added to the UDP packet to prevent alteration of packets. By default the
2628 first 4 bytes of the digest are used for this, but this can be changed using
2629 the MACLength configuration variable.
2631 @c ==================================================================
2632 @node Security issues
2633 @subsection Security issues
2635 In August 2000, we discovered the existence of a security hole in all versions
2636 of tinc up to and including 1.0pre2. This had to do with the way we exchanged
2637 keys. Since then, we have been working on a new authentication scheme to make
2638 tinc as secure as possible. The current version uses the OpenSSL library and
2639 uses strong authentication with RSA keys.
2641 On the 29th of December 2001, Jerome Etienne posted a security analysis of tinc
2642 1.0pre4. Due to a lack of sequence numbers and a message authentication code
2643 for each packet, an attacker could possibly disrupt certain network services or
2644 launch a denial of service attack by replaying intercepted packets. The current
2645 version adds sequence numbers and message authentication codes to prevent such
2648 On the 15th of September 2003, Peter Gutmann posted a security analysis of tinc
2649 1.0.1. He argues that the 32 bit sequence number used by tinc is not a good IV,
2650 that tinc's default length of 4 bytes for the MAC is too short, and he doesn't
2651 like tinc's use of RSA during authentication. We do not know of a security hole
2652 in this version of tinc, but tinc's security is not as strong as TLS or IPsec.
2653 We will address these issues in tinc 2.0.
2655 Cryptography is a hard thing to get right. We cannot make any
2656 guarantees. Time, review and feedback are the only things that can
2657 prove the security of any cryptographic product. If you wish to review
2658 tinc or give us feedback, you are stronly encouraged to do so.
2661 @c ==================================================================
2662 @node Platform specific information
2663 @chapter Platform specific information
2666 * Interface configuration::
2670 @c ==================================================================
2671 @node Interface configuration
2672 @section Interface configuration
2674 When configuring an interface, one normally assigns it an address and a
2675 netmask. The address uniquely identifies the host on the network attached to
2676 the interface. The netmask, combined with the address, forms a subnet. It is
2677 used to add a route to the routing table instructing the kernel to send all
2678 packets which fall into that subnet to that interface. Because all packets for
2679 the entire VPN should go to the virtual network interface used by tinc, the
2680 netmask should be such that it encompasses the entire VPN.
2684 @multitable {Darwin (MacOS/X)} {ifconfig route add -bla network address netmask netmask prefixlength interface}
2686 @tab @code{ifconfig} @var{interface} @var{address} @code{netmask} @var{netmask}
2687 @item Linux iproute2
2688 @tab @code{ip addr add} @var{address}@code{/}@var{prefixlength} @code{dev} @var{interface}
2690 @tab @code{ifconfig} @var{interface} @var{address} @code{netmask} @var{netmask}
2692 @tab @code{ifconfig} @var{interface} @var{address} @code{netmask} @var{netmask}
2694 @tab @code{ifconfig} @var{interface} @var{address} @code{netmask} @var{netmask}
2696 @tab @code{ifconfig} @var{interface} @var{address} @code{netmask} @var{netmask}
2697 @item Darwin (MacOS/X)
2698 @tab @code{ifconfig} @var{interface} @var{address} @code{netmask} @var{netmask}
2700 @tab @code{netsh interface ip set address} @var{interface} @code{static} @var{address} @var{netmask}
2705 @multitable {Darwin (MacOS/X)} {ifconfig route add -bla network address netmask netmask prefixlength interface}
2707 @tab @code{ifconfig} @var{interface} @code{add} @var{address}@code{/}@var{prefixlength}
2709 @tab @code{ifconfig} @var{interface} @code{inet6} @var{address} @code{prefixlen} @var{prefixlength}
2711 @tab @code{ifconfig} @var{interface} @code{inet6} @var{address} @code{prefixlen} @var{prefixlength}
2713 @tab @code{ifconfig} @var{interface} @code{inet6} @var{address} @code{prefixlen} @var{prefixlength}
2715 @tab @code{ifconfig} @var{interface} @code{inet6 plumb up}
2717 @tab @code{ifconfig} @var{interface} @code{inet6 addif} @var{address} @var{address}
2718 @item Darwin (MacOS/X)
2719 @tab @code{ifconfig} @var{interface} @code{inet6} @var{address} @code{prefixlen} @var{prefixlength}
2721 @tab @code{netsh interface ipv6 add address} @var{interface} @code{static} @var{address}/@var{prefixlength}
2724 On some platforms, when running tinc in switch mode, the VPN interface must be set to tap mode with an ifconfig command:
2726 @multitable {Darwin (MacOS/X)} {ifconfig route add -bla network address netmask netmask prefixlength interface}
2728 @tab @code{ifconfig} @var{interface} @code{link0}
2731 On Linux, it is possible to create a persistent tun/tap interface which will
2732 continue to exist even if tinc quit, although this is normally not required.
2733 It can be useful to set up a tun/tap interface owned by a non-root user, so
2734 tinc can be started without needing any root privileges at all.
2736 @multitable {Darwin (MacOS/X)} {ifconfig route add -bla network address netmask netmask prefixlength interface}
2738 @tab @code{ip tuntap add dev} @var{interface} @code{mode} @var{tun|tap} @code{user} @var{username}
2741 @c ==================================================================
2745 In some cases it might be necessary to add more routes to the virtual network
2746 interface. There are two ways to indicate which interface a packet should go
2747 to, one is to use the name of the interface itself, another way is to specify
2748 the (local) address that is assigned to that interface (@var{local_address}). The
2749 former way is unambiguous and therefore preferable, but not all platforms
2752 Adding routes to IPv4 subnets:
2754 @multitable {Darwin (MacOS/X)} {ifconfig route add -bla network address netmask netmask prefixlength interface}
2756 @tab @code{route add -net} @var{network_address} @code{netmask} @var{netmask} @var{interface}
2757 @item Linux iproute2
2758 @tab @code{ip route add} @var{network_address}@code{/}@var{prefixlength} @code{dev} @var{interface}
2760 @tab @code{route add} @var{network_address}@code{/}@var{prefixlength} @var{local_address}
2762 @tab @code{route add} @var{network_address}@code{/}@var{prefixlength} @var{local_address}
2764 @tab @code{route add} @var{network_address}@code{/}@var{prefixlength} @var{local_address}
2766 @tab @code{route add} @var{network_address}@code{/}@var{prefixlength} @var{local_address} @code{-interface}
2767 @item Darwin (MacOS/X)
2768 @tab @code{route add} @var{network_address}@code{/}@var{prefixlength} @var{local_address}
2770 @tab @code{netsh routing ip add persistentroute} @var{network_address} @var{netmask} @var{interface} @var{local_address}
2773 Adding routes to IPv6 subnets:
2775 @multitable {Darwin (MacOS/X)} {ifconfig route add -bla network address netmask netmask prefixlength interface}
2777 @tab @code{route add -A inet6} @var{network_address}@code{/}@var{prefixlength} @var{interface}
2778 @item Linux iproute2
2779 @tab @code{ip route add} @var{network_address}@code{/}@var{prefixlength} @code{dev} @var{interface}
2781 @tab @code{route add -inet6} @var{network_address}@code{/}@var{prefixlength} @var{local_address}
2783 @tab @code{route add -inet6} @var{network_address} @var{local_address} @code{-prefixlen} @var{prefixlength}
2785 @tab @code{route add -inet6} @var{network_address} @var{local_address} @code{-prefixlen} @var{prefixlength}
2787 @tab @code{route add -inet6} @var{network_address}@code{/}@var{prefixlength} @var{local_address} @code{-interface}
2788 @item Darwin (MacOS/X)
2791 @tab @code{netsh interface ipv6 add route} @var{network address}/@var{prefixlength} @var{interface}
2795 @c ==================================================================
2801 * Contact information::
2806 @c ==================================================================
2807 @node Contact information
2808 @section Contact information
2811 Tinc's website is at @url{http://www.tinc-vpn.org/},
2812 this server is located in the Netherlands.
2815 We have an IRC channel on the FreeNode and OFTC IRC networks. Connect to
2816 @uref{http://www.freenode.net/, irc.freenode.net}
2818 @uref{http://www.oftc.net/, irc.oftc.net}
2819 and join channel #tinc.
2822 @c ==================================================================
2827 @item Ivo Timmermans (zarq)
2828 @item Guus Sliepen (guus) (@email{guus@@tinc-vpn.org})
2831 We have received a lot of valuable input from users. With their help,
2832 tinc has become the flexible and robust tool that it is today. We have
2833 composed a list of contributions, in the file called @file{THANKS} in
2834 the source distribution.
2837 @c ==================================================================
2839 @unnumbered Concept Index
2841 @c ==================================================================
2845 @c ==================================================================