1 \input texinfo @c -*-texinfo-*-
9 @include tincinclude.texi
12 @dircategory Networking tools
14 * tinc: (tinc). The tinc Manual.
17 This is the info manual for @value{PACKAGE} version @value{VERSION}, a Virtual Private Network daemon.
19 Copyright @copyright{} 1998-2008 Ivo Timmermans,
20 Guus Sliepen <guus@@tinc-vpn.org> and
21 Wessel Dankers <wsl@@tinc-vpn.org>.
25 Permission is granted to make and distribute verbatim copies of this
26 manual provided the copyright notice and this permission notice are
27 preserved on all copies.
29 Permission is granted to copy and distribute modified versions of this
30 manual under the conditions for verbatim copying, provided that the
31 entire resulting derived work is distributed under the terms of a
32 permission notice identical to this one.
38 @subtitle Setting up a Virtual Private Network with tinc
39 @author Ivo Timmermans and Guus Sliepen
42 @vskip 0pt plus 1filll
44 This is the info manual for @value{PACKAGE} version @value{VERSION}, a Virtual Private Network daemon.
46 Copyright @copyright{} 1998-2006 Ivo Timmermans,
47 Guus Sliepen <guus@@tinc-vpn.org> and
48 Wessel Dankers <wsl@@tinc-vpn.org>.
52 Permission is granted to make and distribute verbatim copies of this
53 manual provided the copyright notice and this permission notice are
54 preserved on all copies.
56 Permission is granted to copy and distribute modified versions of this
57 manual under the conditions for verbatim copying, provided that the
58 entire resulting derived work is distributed under the terms of a
59 permission notice identical to this one.
64 @c ==================================================================
74 * Technical information::
75 * Platform specific information::
77 * Concept Index:: All used terms explained
81 @c ==================================================================
86 Tinc is a Virtual Private Network (VPN) daemon that uses tunneling and
87 encryption to create a secure private network between hosts on the
90 Because the tunnel appears to the IP level network code as a normal
91 network device, there is no need to adapt any existing software.
92 The encrypted tunnels allows VPN sites to share information with each other
93 over the Internet without exposing any information to others.
95 This document is the manual for tinc. Included are chapters on how to
96 configure your computer to use tinc, as well as the configuration
97 process of tinc itself.
100 * Virtual Private Networks::
102 * Supported platforms::
105 @c ==================================================================
106 @node Virtual Private Networks
107 @section Virtual Private Networks
110 A Virtual Private Network or VPN is a network that can only be accessed
111 by a few elected computers that participate. This goal is achievable in
112 more than just one way.
115 Private networks can consist of a single stand-alone Ethernet LAN. Or
116 even two computers hooked up using a null-modem cable. In these cases,
118 obvious that the network is @emph{private}, no one can access it from the
119 outside. But if your computers are linked to the Internet, the network
120 is not private anymore, unless one uses firewalls to block all private
121 traffic. But then, there is no way to send private data to trusted
122 computers on the other end of the Internet.
125 This problem can be solved by using @emph{virtual} networks. Virtual
126 networks can live on top of other networks, but they use encapsulation to
127 keep using their private address space so they do not interfere with
128 the Internet. Mostly, virtual networks appear like a singe LAN, even though
129 they can span the entire world. But virtual networks can't be secured
130 by using firewalls, because the traffic that flows through it has to go
131 through the Internet, where other people can look at it.
133 As is the case with either type of VPN, anybody could eavesdrop. Or
134 worse, alter data. Hence it's probably advisable to encrypt the data
135 that flows over the network.
137 When one introduces encryption, we can form a true VPN. Other people may
138 see encrypted traffic, but if they don't know how to decipher it (they
139 need to know the key for that), they cannot read the information that flows
140 through the VPN. This is what tinc was made for.
143 @c ==================================================================
148 I really don't quite remember what got us started, but it must have been
149 Guus' idea. He wrote a simple implementation (about 50 lines of C) that
150 used the ethertap device that Linux knows of since somewhere
151 about kernel 2.1.60. It didn't work immediately and he improved it a
152 bit. At this stage, the project was still simply called "vpnd".
154 Since then, a lot has changed---to say the least.
157 Tinc now supports encryption, it consists of a single daemon (tincd) for
158 both the receiving and sending end, it has become largely
159 runtime-configurable---in short, it has become a full-fledged
160 professional package.
162 @cindex traditional VPNs
164 Tinc also allows more than two sites to connect to eachother and form a single VPN.
165 Traditionally VPNs are created by making tunnels, which only have two endpoints.
166 Larger VPNs with more sites are created by adding more tunnels.
167 Tinc takes another approach: only endpoints are specified,
168 the software itself will take care of creating the tunnels.
169 This allows for easier configuration and improved scalability.
171 A lot can---and will be---changed. We have a number of things that we would like to
172 see in the future releases of tinc. Not everything will be available in
173 the near future. Our first objective is to make tinc work perfectly as
174 it stands, and then add more advanced features.
176 Meanwhile, we're always open-minded towards new ideas. And we're
180 @c ==================================================================
181 @node Supported platforms
182 @section Supported platforms
185 Tinc has been verified to work under Linux, FreeBSD, OpenBSD, NetBSD, MacOS/X (Darwin), Solaris, and Windows (both natively and in a Cygwin environment),
186 with various hardware architectures. These are some of the platforms
187 that are supported by the universal tun/tap device driver or other virtual network device drivers.
188 Without such a driver, tinc will most
189 likely compile and run, but it will not be able to send or receive data
193 For an up to date list of supported platforms, please check the list on
195 @uref{http://www.tinc-vpn.org/platforms}.
203 @c Preparing your system
210 @c ==================================================================
212 @chapter Preparations
214 This chapter contains information on how to prepare your system to
218 * Configuring the kernel::
223 @c ==================================================================
224 @node Configuring the kernel
225 @section Configuring the kernel
228 * Configuration of Linux kernels::
229 * Configuration of FreeBSD kernels::
230 * Configuration of OpenBSD kernels::
231 * Configuration of NetBSD kernels::
232 * Configuration of Solaris kernels::
233 * Configuration of Darwin (MacOS/X) kernels::
234 * Configuration of Windows::
238 @c ==================================================================
239 @node Configuration of Linux kernels
240 @subsection Configuration of Linux kernels
242 @cindex Universal tun/tap
243 For tinc to work, you need a kernel that supports the Universal tun/tap device.
244 Most distributions come with kernels that already support this.
245 Here are the options you have to turn on when configuring a new kernel:
248 Code maturity level options
249 [*] Prompt for development and/or incomplete code/drivers
250 Network device support
251 <M> Universal tun/tap device driver support
254 It's not necessary to compile this driver as a module, even if you are going to
255 run more than one instance of tinc.
257 If you decide to build the tun/tap driver as a kernel module, add these lines
258 to @file{/etc/modules.conf}:
261 alias char-major-10-200 tun
265 @c ==================================================================
266 @node Configuration of FreeBSD kernels
267 @subsection Configuration of FreeBSD kernels
269 For FreeBSD version 4.1 and higher, tun and tap drivers are included in the default kernel configuration.
270 Using tap devices is recommended.
273 @c ==================================================================
274 @node Configuration of OpenBSD kernels
275 @subsection Configuration of OpenBSD kernels
277 For OpenBSD version 2.9 and higher,
278 the tun driver is included in the default kernel configuration.
279 There is also a kernel patch from @uref{http://diehard.n-r-g.com/stuff/openbsd/}
280 which adds a tap device to OpenBSD which should work with tinc,
281 but with recent versions of OpenBSD,
282 a tun device can act as a tap device by setting the link0 option with ifconfig.
284 @c ==================================================================
285 @node Configuration of NetBSD kernels
286 @subsection Configuration of NetBSD kernels
288 For NetBSD version 1.5.2 and higher,
289 the tun driver is included in the default kernel configuration.
291 Tunneling IPv6 may not work on NetBSD's tun device.
294 @c ==================================================================
295 @node Configuration of Solaris kernels
296 @subsection Configuration of Solaris kernels
298 For Solaris 8 (SunOS 5.8) and higher,
299 the tun driver may or may not be included in the default kernel configuration.
300 If it isn't, the source can be downloaded from @uref{http://vtun.sourceforge.net/tun/}.
301 For x86 and sparc64 architectures, precompiled versions can be found at @uref{http://www.monkey.org/~dugsong/fragroute/}.
302 If the @file{net/if_tun.h} header file is missing, install it from the source package.
305 @c ==================================================================
306 @node Configuration of Darwin (MacOS/X) kernels
307 @subsection Configuration of Darwin (MacOS/X) kernels
309 Tinc on Darwin relies on a tunnel driver for its data acquisition from the kernel.
310 Tinc supports either the driver from @uref{http://www-user.rhrk.uni-kl.de/~nissler/tuntap/},
311 which supports both tun and tap style devices,
312 and also the driver from from @uref{http://chrisp.de/en/projects/tunnel.html}.
313 The former driver is recommended.
314 The tunnel driver must be loaded before starting tinc with the following command:
321 @c ==================================================================
322 @node Configuration of Windows
323 @subsection Configuration of Windows
325 You will need to install the latest TAP-Win32 driver from OpenVPN.
326 You can download it from @uref{http://openvpn.sourceforge.net}.
327 Using the Network Connections control panel,
328 configure the TAP-Win32 network interface in the same way as you would do from the tinc-up script,
329 as explained in the rest of the documentation.
332 @c ==================================================================
338 Before you can configure or build tinc, you need to have the OpenSSL,
339 zlib and lzo libraries installed on your system. If you try to configure tinc without
340 having them installed, configure will give you an error message, and stop.
349 @c ==================================================================
354 For all cryptography-related functions, tinc uses the functions provided
355 by the OpenSSL library.
357 If this library is not installed, you wil get an error when configuring
358 tinc for build. Support for running tinc without having OpenSSL
359 installed @emph{may} be added in the future.
361 You can use your operating system's package manager to install this if
362 available. Make sure you install the development AND runtime versions
365 If you have to install OpenSSL manually, you can get the source code
366 from @url{http://www.openssl.org/}. Instructions on how to configure,
367 build and install this package are included within the package. Please
368 make sure you build development and runtime libraries (which is the
371 If you installed the OpenSSL libraries from source, it may be necessary
372 to let configure know where they are, by passing configure one of the
373 --with-openssl-* parameters.
376 --with-openssl=DIR OpenSSL library and headers prefix
377 --with-openssl-include=DIR OpenSSL headers directory
378 (Default is OPENSSL_DIR/include)
379 --with-openssl-lib=DIR OpenSSL library directory
380 (Default is OPENSSL_DIR/lib)
384 @subsubheading License
387 The complete source code of tinc is covered by the GNU GPL version 2.
388 Since the license under which OpenSSL is distributed is not directly
389 compatible with the terms of the GNU GPL
390 @uref{http://www.openssl.org/support/faq.html#LEGAL2}, we
391 include an exemption to the GPL (see also the file COPYING.README) to allow
392 everyone to create a statically or dynamically linked executable:
395 This program is released under the GPL with the additional exemption
396 that compiling, linking, and/or using OpenSSL is allowed. You may
397 provide binary packages linked to the OpenSSL libraries, provided that
398 all other requirements of the GPL are met.
401 Since the LZO library used by tinc is also covered by the GPL,
402 we also present the following exemption:
405 Hereby I grant a special exception to the tinc VPN project
406 (http://www.tinc-vpn.org/) to link the LZO library with the OpenSSL library
407 (http://www.openssl.org).
409 Markus F.X.J. Oberhumer
413 @c ==================================================================
418 For the optional compression of UDP packets, tinc uses the functions provided
421 If this library is not installed, you wil get an error when configuring
422 tinc for build. Support for running tinc without having zlib
423 installed @emph{may} be added in the future.
425 You can use your operating system's package manager to install this if
426 available. Make sure you install the development AND runtime versions
429 If you have to install zlib manually, you can get the source code
430 from @url{http://www.gzip.org/zlib/}. Instructions on how to configure,
431 build and install this package are included within the package. Please
432 make sure you build development and runtime libraries (which is the
436 @c ==================================================================
441 Another form of compression is offered using the lzo library.
443 If this library is not installed, you wil get an error when configuring
444 tinc for build. Support for running tinc without having lzo
445 installed @emph{may} be added in the future.
447 You can use your operating system's package manager to install this if
448 available. Make sure you install the development AND runtime versions
451 If you have to install lzo manually, you can get the source code
452 from @url{http://www.oberhumer.com/opensource/lzo/}. Instructions on how to configure,
453 build and install this package are included within the package. Please
454 make sure you build development and runtime libraries (which is the
467 @c ==================================================================
469 @chapter Installation
471 If you use Debian, you may want to install one of the
472 precompiled packages for your system. These packages are equipped with
473 system startup scripts and sample configurations.
475 If you cannot use one of the precompiled packages, or you want to compile tinc
476 for yourself, you can use the source. The source is distributed under
477 the GNU General Public License (GPL). Download the source from the
478 @uref{http://www.tinc-vpn.org/download, download page}, which has
479 the checksums of these files listed; you may wish to check these with
480 md5sum before continuing.
482 Tinc comes in a convenient autoconf/automake package, which you can just
483 treat the same as any other package. Which is just untar it, type
484 `./configure' and then `make'.
485 More detailed instructions are in the file @file{INSTALL}, which is
486 included in the source distribution.
489 * Building and installing tinc::
494 @c ==================================================================
495 @node Building and installing tinc
496 @section Building and installing tinc
498 Detailed instructions on configuring the source, building tinc and installing tinc
499 can be found in the file called @file{INSTALL}.
501 @cindex binary package
502 If you happen to have a binary package for tinc for your distribution,
503 you can use the package management tools of that distribution to install tinc.
504 The documentation that comes along with your distribution will tell you how to do that.
507 * Darwin (MacOS/X) build environment::
508 * Cygwin (Windows) build environment::
509 * MinGW (Windows) build environment::
513 @c ==================================================================
514 @node Darwin (MacOS/X) build environment
515 @subsection Darwin (MacOS/X) build environment
517 In order to build tinc on Darwin, you need to install the MacOS/X Developer Tools
518 from @uref{http://developer.apple.com/tools/macosxtools.html} and
519 a recent version of Fink from @uref{http://fink.sourceforge.net/}.
521 After installation use fink to download and install the following packages:
522 autoconf25, automake, dlcompat, m4, openssl, zlib and lzo.
524 @c ==================================================================
525 @node Cygwin (Windows) build environment
526 @subsection Cygwin (Windows) build environment
528 If Cygwin hasn't already been installed, install it directly from
529 @uref{http://www.cygwin.com/}.
531 When tinc is compiled in a Cygwin environment, it can only be run in this environment,
532 but all programs, including those started outside the Cygwin environment, will be able to use the VPN.
533 It will also support all features.
535 @c ==================================================================
536 @node MinGW (Windows) build environment
537 @subsection MinGW (Windows) build environment
539 You will need to install the MinGW environment from @uref{http://www.mingw.org}.
541 When tinc is compiled using MinGW it runs natively under Windows,
542 it is not necessary to keep MinGW installed.
544 When detaching, tinc will install itself as a service,
545 which will be restarted automatically after reboots.
548 @c ==================================================================
550 @section System files
552 Before you can run tinc, you must make sure you have all the needed
553 files on your system.
561 @c ==================================================================
563 @subsection Device files
566 Most operating systems nowadays come with the necessary device files by default,
567 or they have a mechanism to create them on demand.
569 If you use Linux and do not have udev installed,
570 you may need to create the following device file if it does not exist:
573 mknod -m 600 /dev/net/tun c 10 200
577 @c ==================================================================
579 @subsection Other files
581 @subsubheading @file{/etc/networks}
583 You may add a line to @file{/etc/networks} so that your VPN will get a
584 symbolic name. For example:
590 @subsubheading @file{/etc/services}
593 You may add this line to @file{/etc/services}. The effect is that you
594 may supply a @samp{tinc} as a valid port number to some programs. The
595 number 655 is registered with the IANA.
600 # Ivo Timmermans <ivo@@tinc-vpn.org>
615 @c ==================================================================
617 @chapter Configuration
620 * Configuration introduction::
621 * Multiple networks::
622 * How connections work::
623 * Configuration files::
624 * Generating keypairs::
625 * Network interfaces::
626 * Example configuration::
629 @c ==================================================================
630 @node Configuration introduction
631 @section Configuration introduction
633 Before actually starting to configure tinc and editing files,
634 make sure you have read this entire section so you know what to expect.
635 Then, make it clear to yourself how you want to organize your VPN:
636 What are the nodes (computers running tinc)?
637 What IP addresses/subnets do they have?
638 What is the network mask of the entire VPN?
639 Do you need special firewall rules?
640 Do you have to set up masquerading or forwarding rules?
641 Do you want to run tinc in router mode or switch mode?
642 These questions can only be answered by yourself,
643 you will not find the answers in this documentation.
644 Make sure you have an adequate understanding of networks in general.
645 @cindex Network Administrators Guide
646 A good resource on networking is the
647 @uref{http://www.linuxdoc.org/LDP/nag2/, Linux Network Administrators Guide}.
649 If you have everything clearly pictured in your mind,
650 proceed in the following order:
651 First, generate the configuration files (@file{tinc.conf}, your host configuration file, @file{tinc-up} and perhaps @file{tinc-down}).
652 Then generate the keypairs.
653 Finally, distribute the host configuration files.
654 These steps are described in the subsections below.
657 @c ==================================================================
658 @node Multiple networks
659 @section Multiple networks
661 @cindex multiple networks
663 In order to allow you to run more than one tinc daemon on one computer,
664 for instance if your computer is part of more than one VPN,
665 you can assign a @var{netname} to your VPN.
666 It is not required if you only run one tinc daemon,
667 it doesn't even have to be the same on all the sites of your VPN,
668 but it is recommended that you choose one anyway.
670 We will asume you use a netname throughout this document.
671 This means that you call tincd with the -n argument,
672 which will assign a netname to this daemon.
674 The effect of this is that the daemon will set its configuration
675 root to @file{@value{sysconfdir}/tinc/@var{netname}/}, where @var{netname} is your argument to the -n
676 option. You'll notice that it appears in syslog as @file{tinc.@var{netname}}.
678 However, it is not strictly necessary that you call tinc with the -n
679 option. In this case, the network name would just be empty, and it will
680 be used as such. tinc now looks for files in @file{@value{sysconfdir}/tinc/}, instead of
681 @file{@value{sysconfdir}/tinc/@var{netname}/}; the configuration file should be @file{@value{sysconfdir}/tinc/tinc.conf},
682 and the host configuration files are now expected to be in @file{@value{sysconfdir}/tinc/hosts/}.
684 But it is highly recommended that you use this feature of tinc, because
685 it will be so much clearer whom your daemon talks to. Hence, we will
686 assume that you use it.
689 @c ==================================================================
690 @node How connections work
691 @section How connections work
693 When tinc starts up, it parses the command-line options and then
694 reads in the configuration file tinc.conf.
695 If it sees one or more `ConnectTo' values pointing to other tinc daemons in that file,
696 it will try to connect to those other daemons.
697 Whether this succeeds or not and whether `ConnectTo' is specified or not,
698 tinc will listen for incoming connection from other deamons.
699 If you did specify a `ConnectTo' value and the other side is not responding,
700 tinc will keep retrying.
701 This means that once started, tinc will stay running until you tell it to stop,
702 and failures to connect to other tinc daemons will not stop your tinc daemon
703 for trying again later.
704 This means you don't have to intervene if there are temporary network problems.
708 There is no real distinction between a server and a client in tinc.
709 If you wish, you can view a tinc daemon without a `ConnectTo' value as a server,
710 and one which does specify such a value as a client.
711 It does not matter if two tinc daemons have a `ConnectTo' value pointing to each other however.
714 @c ==================================================================
715 @node Configuration files
716 @section Configuration files
718 The actual configuration of the daemon is done in the file
719 @file{@value{sysconfdir}/tinc/@var{netname}/tinc.conf} and at least one other file in the directory
720 @file{@value{sysconfdir}/tinc/@var{netname}/hosts/}.
722 These file consists of comments (lines started with a #) or assignments
729 The variable names are case insensitive, and any spaces, tabs, newlines
730 and carriage returns are ignored. Note: it is not required that you put
731 in the `=' sign, but doing so improves readability. If you leave it
732 out, remember to replace it with at least one space character.
734 In this section all valid variables are listed in alphabetical order.
735 The default value is given between parentheses,
736 other comments are between square brackets.
739 * Main configuration variables::
740 * Host configuration variables::
746 @c ==================================================================
747 @node Main configuration variables
748 @subsection Main configuration variables
751 @cindex AddressFamily
752 @item AddressFamily = <ipv4|ipv6|any> (any)
753 This option affects the address family of listening and outgoing sockets.
754 If any is selected, then depending on the operating system
755 both IPv4 and IPv6 or just IPv6 listening sockets will be created.
757 @cindex BindToAddress
758 @item BindToAddress = <@var{address}> [experimental]
759 If your computer has more than one IPv4 or IPv6 address, tinc
760 will by default listen on all of them for incoming connections.
761 It is possible to bind only to a single address with this variable.
763 This option may not work on all platforms.
765 @cindex BindToInterface
766 @item BindToInterface = <@var{interface}> [experimental]
767 If you have more than one network interface in your computer, tinc will
768 by default listen on all of them for incoming connections. It is
769 possible to bind tinc to a single interface like eth0 or ppp0 with this
772 This option may not work on all platforms.
775 @item ConnectTo = <@var{name}>
776 Specifies which other tinc daemon to connect to on startup.
777 Multiple ConnectTo variables may be specified,
778 in which case outgoing connections to each specified tinc daemon are made.
779 The names should be known to this tinc daemon
780 (i.e., there should be a host configuration file for the name on the ConnectTo line).
782 If you don't specify a host with ConnectTo,
783 tinc won't try to connect to other daemons at all,
784 and will instead just listen for incoming connections.
787 @item Device = <@var{device}> (@file{/dev/tap0}, @file{/dev/net/tun} or other depending on platform)
788 The virtual network device to use.
789 Tinc will automatically detect what kind of device it is.
790 Note that you can only use one device per daemon.
791 Under Windows, use @var{Interface} instead of @var{Device}.
792 Note that you can only use one device per daemon.
793 See also @ref{Device files}.
796 @item DeviceType = <tun|tunnohead|tunifhead|tap> (only supported on BSD platforms)
797 The type of the virtual network device.
798 Tinc will normally automatically select the right type, and this option should not be used.
799 However, in case tinc does not seem to correctly interpret packets received from the virtual network device,
800 using this option might help.
805 Depending on the platform, this can either be with or without an address family header (see below).
809 Set type to tun without an address family header.
810 Tinc will expect packets read from the virtual network device to start with an IP header.
811 On some platforms IPv6 packets cannot be read from or written to the device in this mode.
815 Set type to tun with an address family header.
816 Tinc will expect packets read from the virtual network device
817 to start with a four byte header containing the address family,
818 followed by an IP header.
819 This mode should support both IPv4 and IPv6 packets.
823 Tinc will expect packets read from the virtual network device
824 to start with an Ethernet header.
827 @cindex GraphDumpFile
828 @item GraphDumpFile = <@var{filename}> [experimental]
829 If this option is present,
830 tinc will dump the current network graph to the file @var{filename}
831 every minute, unless there were no changes to the graph.
832 The file is in a format that can be read by graphviz tools.
833 If @var{filename} starts with a pipe symbol |,
834 then the rest of the filename is interpreted as a shell command
835 that is executed, the graph is then sent to stdin.
838 @item Hostnames = <yes|no> (no)
839 This option selects whether IP addresses (both real and on the VPN)
840 should be resolved. Since DNS lookups are blocking, it might affect
841 tinc's efficiency, even stopping the daemon for a few seconds everytime
842 it does a lookup if your DNS server is not responding.
844 This does not affect resolving hostnames to IP addresses from the
848 @item Interface = <@var{interface}>
849 Defines the name of the interface corresponding to the virtual network device.
850 Depending on the operating system and the type of device this may or may not actually set the name of the interface.
851 Under Windows, this variable is used to select which network interface will be used.
852 If you specified a Device, this variable is almost always already correctly set.
855 @item Mode = <router|switch|hub> (router)
856 This option selects the way packets are routed to other daemons.
862 variables in the host configuration files will be used to form a routing table.
863 Only unicast packets of routable protocols (IPv4 and IPv6) are supported in this mode.
865 This is the default mode, and unless you really know you need another mode, don't change it.
869 In this mode the MAC addresses of the packets on the VPN will be used to
870 dynamically create a routing table just like an Ethernet switch does.
871 Unicast, multicast and broadcast packets of every protocol that runs over Ethernet are supported in this mode
872 at the cost of frequent broadcast ARP requests and routing table updates.
874 This mode is primarily useful if you want to bridge Ethernet segments.
878 This mode is almost the same as the switch mode, but instead
879 every packet will be broadcast to the other daemons
880 while no routing table is managed.
884 @item KeyExpire = <@var{seconds}> (3600)
885 This option controls the time the encryption keys used to encrypt the data
886 are valid. It is common practice to change keys at regular intervals to
887 make it even harder for crackers, even though it is thought to be nearly
888 impossible to crack a single key.
891 @item MACExpire = <@var{seconds}> (600)
892 This option controls the amount of time MAC addresses are kept before they are removed.
893 This only has effect when Mode is set to "switch".
896 @item Name = <@var{name}> [required]
897 This is a symbolic name for this connection.
898 The name should consist only of alfanumeric and underscore characters (a-z, A-Z, 0-9 and _).
901 @item PingInterval = <@var{seconds}> (60)
902 The number of seconds of inactivity that tinc will wait before sending a
903 probe to the other end.
906 @item PingTimeout = <@var{seconds}> (5)
907 The number of seconds to wait for a response to pings or to allow meta
908 connections to block. If the other end doesn't respond within this time,
909 the connection is terminated, and the others will be notified of this.
911 @cindex PriorityInheritance
912 @item PriorityInheritance = <yes|no> (no) [experimental]
913 When this option is enabled the value of the TOS field of tunneled IPv4 packets
914 will be inherited by the UDP packets that are sent out.
917 @item PrivateKey = <@var{key}> [obsolete]
918 This is the RSA private key for tinc. However, for safety reasons it is
919 advised to store private keys of any kind in separate files. This prevents
920 accidental eavesdropping if you are editting the configuration file.
922 @cindex PrivateKeyFile
923 @item PrivateKeyFile = <@var{path}> (@file{@value{sysconfdir}/tinc/@var{netname}/rsa_key.priv})
924 This is the full path name of the RSA private key file that was
925 generated by @samp{tincd --generate-keys}. It must be a full path, not a
928 Note that there must be exactly one of PrivateKey
930 specified in the configuration file.
933 @item TunnelServer = <yes|no> (no) [experimental]
934 When this option is enabled tinc will no longer forward information between other tinc daemons,
935 and will only allow nodes and subnets on the VPN which are present in the
936 @file{@value{sysconfdir}/tinc/@var{netname}/hosts/} directory.
941 @c ==================================================================
942 @node Host configuration variables
943 @subsection Host configuration variables
947 @item Address = <@var{IP address}|@var{hostname}> [recommended]
948 This variable is only required if you want to connect to this host. It
949 must resolve to the external IP address where the host can be reached,
950 not the one that is internal to the VPN.
953 @item Cipher = <@var{cipher}> (blowfish)
954 The symmetric cipher algorithm used to encrypt UDP packets.
955 Any cipher supported by OpenSSL is recognized.
956 Furthermore, specifying "none" will turn off packet encryption.
957 It is best to use only those ciphers which support CBC mode.
960 @item Compression = <@var{level}> (0)
961 This option sets the level of compression used for UDP packets.
962 Possible values are 0 (off), 1 (fast zlib) and any integer up to 9 (best zlib),
963 10 (fast lzo) and 11 (best lzo).
966 @item Digest = <@var{digest}> (sha1)
967 The digest algorithm used to authenticate UDP packets.
968 Any digest supported by OpenSSL is recognized.
969 Furthermore, specifying "none" will turn off packet authentication.
972 @item IndirectData = <yes|no> (no)
973 This option specifies whether other tinc daemons besides the one you
974 specified with ConnectTo can make a direct connection to you. This is
975 especially useful if you are behind a firewall and it is impossible to
976 make a connection from the outside to your tinc daemon. Otherwise, it
977 is best to leave this option out or set it to no.
980 @item MACLength = <@var{bytes}> (4)
981 The length of the message authentication code used to authenticate UDP packets.
982 Can be anything from 0
983 up to the length of the digest produced by the digest algorithm.
986 @item PMTU = <@var{mtu}> (1514)
987 This option controls the initial path MTU to this node.
989 @cindex PMTUDiscovery
990 @item PMTUDiscovery = <yes|no> (yes)
991 When this option is enabled, tinc will try to discover the path MTU to this node.
992 After the path MTU has been discovered, it will be enforced on the VPN.
995 @item Port = <@var{port}> (655)
996 This is the port this tinc daemon listens on.
997 You can use decimal portnumbers or symbolic names (as listed in @file{/etc/services}).
1000 @item PublicKey = <@var{key}> [obsolete]
1001 This is the RSA public key for this host.
1003 @cindex PublicKeyFile
1004 @item PublicKeyFile = <@var{path}> [obsolete]
1005 This is the full path name of the RSA public key file that was generated
1006 by @samp{tincd --generate-keys}. It must be a full path, not a relative
1010 From version 1.0pre4 on tinc will store the public key directly into the
1011 host configuration file in PEM format, the above two options then are not
1012 necessary. Either the PEM format is used, or exactly
1013 @strong{one of the above two options} must be specified
1014 in each host configuration file, if you want to be able to establish a
1015 connection with that host.
1018 @item Subnet = <@var{address}[/@var{prefixlength}[#@var{weight}]]>
1019 The subnet which this tinc daemon will serve.
1020 Tinc tries to look up which other daemon it should send a packet to by searching the appropiate subnet.
1021 If the packet matches a subnet,
1022 it will be sent to the daemon who has this subnet in his host configuration file.
1023 Multiple subnet lines can be specified for each daemon.
1025 Subnets can either be single MAC, IPv4 or IPv6 addresses,
1026 in which case a subnet consisting of only that single address is assumed,
1027 or they can be a IPv4 or IPv6 network address with a prefixlength.
1028 Shorthand notations are not supported.
1029 For example, IPv4 subnets must be in a form like 192.168.1.0/24,
1030 where 192.168.1.0 is the network address and 24 is the number of bits set in the netmask.
1031 Note that subnets like 192.168.1.1/24 are invalid!
1032 Read a networking HOWTO/FAQ/guide if you don't understand this.
1033 IPv6 subnets are notated like fec0:0:0:1:0:0:0:0/64.
1034 MAC addresses are notated like 0:1a:2b:3c:4d:5e.
1036 @cindex CIDR notation
1037 Prefixlength is the number of bits set to 1 in the netmask part; for
1038 example: netmask 255.255.255.0 would become /24, 255.255.252.0 becomes
1039 /22. This conforms to standard CIDR notation as described in
1040 @uref{ftp://ftp.isi.edu/in-notes/rfc1519.txt, RFC1519}
1042 A Subnet can be given a weight to indicate its priority over identical Subnets
1043 owned by different nodes. The default weight is 10. Lower values indicate
1044 higher priority. Packets will be sent to the node with the highest priority,
1045 unless that node is not reachable, in which case the node with the next highest
1046 priority will be tried, and so on.
1049 @item TCPonly = <yes|no> (no)
1050 If this variable is set to yes, then the packets are tunnelled over a
1051 TCP connection instead of a UDP connection. This is especially useful
1052 for those who want to run a tinc daemon from behind a masquerading
1053 firewall, or if UDP packet routing is disabled somehow.
1054 Setting this options also implicitly sets IndirectData.
1058 @c ==================================================================
1063 Apart from reading the server and host configuration files,
1064 tinc can also run scripts at certain moments.
1065 Under Windows (not Cygwin), the scripts should have the extension .bat.
1069 @item @value{sysconfdir}/tinc/@var{netname}/tinc-up
1070 This is the most important script.
1071 If it is present it will be executed right after the tinc daemon has been
1072 started and has connected to the virtual network device.
1073 It should be used to set up the corresponding network interface,
1074 but can also be used to start other things.
1075 Under Windows you can use the Network Connections control panel instead of creating this script.
1078 @item @value{sysconfdir}/tinc/@var{netname}/tinc-down
1079 This script is started right before the tinc daemon quits.
1081 @item @value{sysconfdir}/tinc/@var{netname}/hosts/@var{host}-up
1082 This script is started when the tinc daemon with name @var{host} becomes reachable.
1084 @item @value{sysconfdir}/tinc/@var{netname}/hosts/@var{host}-down
1085 This script is started when the tinc daemon with name @var{host} becomes unreachable.
1087 @item @value{sysconfdir}/tinc/@var{netname}/host-up
1088 This script is started when any host becomes reachable.
1090 @item @value{sysconfdir}/tinc/@var{netname}/host-down
1091 This script is started when any host becomes unreachable.
1093 @item @value{sysconfdir}/tinc/@var{netname}/subnet-up
1094 This script is started when a Subnet becomes reachable.
1095 The Subnet and the node it belongs to are passed in environment variables.
1097 @item @value{sysconfdir}/tinc/@var{netname}/subnet-down
1098 This script is started when a Subnet becomes unreachable.
1101 @cindex environment variables
1102 The scripts are started without command line arguments,
1103 but can make use of certain environment variables.
1104 Under UNIX like operating systems the names of environment variables must be preceded by a $ in scripts.
1105 Under Windows, in @file{.bat} files, they have to be put between % signs.
1110 If a netname was specified, this environment variable contains it.
1114 Contains the name of this tinc daemon.
1118 Contains the name of the virtual network device that tinc uses.
1122 Contains the name of the virtual network interface that tinc uses.
1123 This should be used for commands like ifconfig.
1127 When a host becomes (un)reachable, this is set to its name.
1128 If a subnet becomes (un)reachable, this is set to the owner of that subnet.
1130 @cindex REMOTEADDRESS
1132 When a host becomes (un)reachable, this is set to its real address.
1136 When a host becomes (un)reachable,
1137 this is set to the port number it uses for communication with other tinc daemons.
1141 When a subnet becomes (un)reachable, this is set to the subnet.
1146 @c ==================================================================
1147 @node How to configure
1148 @subsection How to configure
1150 @subsubheading Step 1. Creating the main configuration file
1152 The main configuration file will be called @file{@value{sysconfdir}/tinc/@var{netname}/tinc.conf}.
1153 Adapt the following example to create a basic configuration file:
1156 Name = @var{yourname}
1157 Device = @file{/dev/tap0}
1160 Then, if you know to which other tinc daemon(s) yours is going to connect,
1161 add `ConnectTo' values.
1163 @subsubheading Step 2. Creating your host configuration file
1165 If you added a line containing `Name = yourname' in the main configuarion file,
1166 you will need to create a host configuration file @file{@value{sysconfdir}/tinc/@var{netname}/hosts/yourname}.
1167 Adapt the following example to create a host configuration file:
1170 Address = your.real.hostname.org
1171 Subnet = 192.168.1.0/24
1174 You can also use an IP address instead of a hostname.
1175 The `Subnet' specifies the address range that is local for @emph{your part of the VPN only}.
1176 If you have multiple address ranges you can specify more than one `Subnet'.
1177 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).
1180 @c ==================================================================
1181 @node Generating keypairs
1182 @section Generating keypairs
1184 @cindex key generation
1185 Now that you have already created the main configuration file and your host configuration file,
1186 you can easily create a public/private keypair by entering the following command:
1189 tincd -n @var{netname} -K
1192 Tinc will generate a public and a private key and ask you where to put them.
1193 Just press enter to accept the defaults.
1196 @c ==================================================================
1197 @node Network interfaces
1198 @section Network interfaces
1200 Before tinc can start transmitting data over the tunnel, it must
1201 set up the virtual network interface.
1203 First, decide which IP addresses you want to have associated with these
1204 devices, and what network mask they must have.
1206 Tinc will open a virtual network device (@file{/dev/tun}, @file{/dev/tap0} or similar),
1207 which will also create a network interface called something like @samp{tun0}, @samp{tap0}.
1208 If you are using the Linux tun/tap driver, the network interface will by default have the same name as the @var{netname}.
1209 Under Windows you can change the name of the network interface from the Network Connections control panel.
1212 You can configure the network interface by putting ordinary ifconfig, route, and other commands
1213 to a script named @file{@value{sysconfdir}/tinc/@var{netname}/tinc-up}.
1214 When tinc starts, this script will be executed. When tinc exits, it will execute the script named
1215 @file{@value{sysconfdir}/tinc/@var{netname}/tinc-down}, but normally you don't need to create that script.
1217 An example @file{tinc-up} script:
1221 ifconfig $INTERFACE 192.168.1.1 netmask 255.255.0.0
1224 This script gives the interface an IP address and a netmask.
1225 The kernel will also automatically add a route to this interface, so normally you don't need
1226 to add route commands to the @file{tinc-up} script.
1227 The kernel will also bring the interface up after this command.
1229 The netmask is the mask of the @emph{entire} VPN network, not just your
1232 The exact syntax of the ifconfig and route commands differs from platform to platform.
1233 You can look up the commands for setting addresses and adding routes in @ref{Platform specific information},
1234 but it is best to consult the manpages of those utilities on your platform.
1237 @c ==================================================================
1238 @node Example configuration
1239 @section Example configuration
1243 Imagine the following situation. Branch A of our example `company' wants to connect
1244 three branch offices in B, C and D using the Internet. All four offices
1245 have a 24/7 connection to the Internet.
1247 A is going to serve as the center of the network. B and C will connect
1248 to A, and D will connect to C. Each office will be assigned their own IP
1252 A: net 10.1.0.0 mask 255.255.0.0 gateway 10.1.54.1 internet IP 1.2.3.4
1253 B: net 10.2.0.0 mask 255.255.0.0 gateway 10.2.1.12 internet IP 2.3.4.5
1254 C: net 10.3.0.0 mask 255.255.0.0 gateway 10.3.69.254 internet IP 3.4.5.6
1255 D: net 10.4.0.0 mask 255.255.0.0 gateway 10.4.3.32 internet IP 4.5.6.7
1258 Here, ``gateway'' is the VPN IP address of the machine that is running the
1259 tincd, and ``internet IP'' is the IP address of the firewall, which does not
1260 need to run tincd, but it must do a port forwarding of TCP and UDP on port
1261 655 (unless otherwise configured).
1263 In this example, it is assumed that eth0 is the interface that points to
1264 the inner (physical) LAN of the office, although this could also be the
1265 same as the interface that leads to the Internet. The configuration of
1266 the real interface is also shown as a comment, to give you an idea of
1267 how these example host is set up. All branches use the netname `company'
1268 for this particular VPN.
1270 @subsubheading For Branch A
1272 @emph{BranchA} would be configured like this:
1274 In @file{@value{sysconfdir}/tinc/company/tinc-up}:
1277 # Real interface of internal network:
1278 # ifconfig eth0 10.1.54.1 netmask 255.255.0.0
1280 ifconfig $INTERFACE 10.1.54.1 netmask 255.0.0.0
1283 and in @file{@value{sysconfdir}/tinc/company/tinc.conf}:
1290 On all hosts, @file{@value{sysconfdir}/tinc/company/hosts/BranchA} contains:
1293 Subnet = 10.1.0.0/16
1296 -----BEGIN RSA PUBLIC KEY-----
1298 -----END RSA PUBLIC KEY-----
1301 Note that the IP addresses of eth0 and tap0 are the same.
1302 This is quite possible, if you make sure that the netmasks of the interfaces are different.
1303 It is in fact recommended to give give both real internal network interfaces and tap interfaces the same IP address,
1304 since that will make things a lot easier to remember and set up.
1307 @subsubheading For Branch B
1309 In @file{@value{sysconfdir}/tinc/company/tinc-up}:
1312 # Real interface of internal network:
1313 # ifconfig eth0 10.2.43.8 netmask 255.255.0.0
1315 ifconfig $INTERFACE 10.2.1.12 netmask 255.0.0.0
1318 and in @file{@value{sysconfdir}/tinc/company/tinc.conf}:
1325 Note here that the internal address (on eth0) doesn't have to be the
1326 same as on the tap0 device. Also, ConnectTo is given so that no-one can
1327 connect to this node.
1329 On all hosts, in @file{@value{sysconfdir}/tinc/company/hosts/BranchB}:
1332 Subnet = 10.2.0.0/16
1335 -----BEGIN RSA PUBLIC KEY-----
1337 -----END RSA PUBLIC KEY-----
1341 @subsubheading For Branch C
1343 In @file{@value{sysconfdir}/tinc/company/tinc-up}:
1346 # Real interface of internal network:
1347 # ifconfig eth0 10.3.69.254 netmask 255.255.0.0
1349 ifconfig $INTERFACE 10.3.69.254 netmask 255.0.0.0
1352 and in @file{@value{sysconfdir}/tinc/company/tinc.conf}:
1360 C already has another daemon that runs on port 655, so they have to
1361 reserve another port for tinc. It knows the portnumber it has to listen on
1362 from it's own host configuration file.
1364 On all hosts, in @file{@value{sysconfdir}/tinc/company/hosts/BranchC}:
1368 Subnet = 10.3.0.0/16
1371 -----BEGIN RSA PUBLIC KEY-----
1373 -----END RSA PUBLIC KEY-----
1377 @subsubheading For Branch D
1379 In @file{@value{sysconfdir}/tinc/company/tinc-up}:
1382 # Real interface of internal network:
1383 # ifconfig eth0 10.4.3.32 netmask 255.255.0.0
1385 ifconfig $INTERFACE 10.4.3.32 netmask 255.0.0.0
1388 and in @file{@value{sysconfdir}/tinc/company/tinc.conf}:
1393 Device = /dev/net/tun
1396 D will be connecting to C, which has a tincd running for this network on
1397 port 2000. It knows the port number from the host configuration file.
1398 Also note that since D uses the tun/tap driver, the network interface
1399 will not be called `tun' or `tap0' or something like that, but will
1400 have the same name as netname.
1402 On all hosts, in @file{@value{sysconfdir}/tinc/company/hosts/BranchD}:
1405 Subnet = 10.4.0.0/16
1408 -----BEGIN RSA PUBLIC KEY-----
1410 -----END RSA PUBLIC KEY-----
1413 @subsubheading Key files
1415 A, B, C and D all have generated a public/private keypair with the following command:
1421 The private key is stored in @file{@value{sysconfdir}/tinc/company/rsa_key.priv},
1422 the public key is put into the host configuration file in the @file{@value{sysconfdir}/tinc/company/hosts/} directory.
1423 During key generation, tinc automatically guesses the right filenames based on the -n option and
1424 the Name directive in the @file{tinc.conf} file (if it is available).
1426 @subsubheading Starting
1428 After each branch has finished configuration and they have distributed
1429 the host configuration files amongst them, they can start their tinc daemons.
1430 They don't necessarily have to wait for the other branches to have started
1431 their daemons, tinc will try connecting until they are available.
1434 @c ==================================================================
1436 @chapter Running tinc
1438 If everything else is done, you can start tinc by typing the following command:
1441 tincd -n @var{netname}
1445 Tinc will detach from the terminal and continue to run in the background like a good daemon.
1446 If there are any problems however you can try to increase the debug level
1447 and look in the syslog to find out what the problems are.
1453 * Solving problems::
1455 * Sending bug reports::
1459 @c ==================================================================
1460 @node Runtime options
1461 @section Runtime options
1463 Besides the settings in the configuration file, tinc also accepts some
1464 command line options.
1466 @cindex command line
1467 @cindex runtime options
1471 @item -c, --config=@var{path}
1472 Read configuration options from the directory @var{path}. The default is
1473 @file{@value{sysconfdir}/tinc/@var{netname}/}.
1475 @item -D, --no-detach
1476 Don't fork and detach.
1477 This will also disable the automatic restart mechanism for fatal errors.
1480 @item -d, --debug=@var{level}
1481 Set debug level to @var{level}. The higher the debug level, the more gets
1482 logged. Everything goes via syslog.
1484 @item -k, --kill[=@var{signal}]
1485 Attempt to kill a running tincd (optionally with the specified @var{signal} instead of SIGTERM) and exit.
1486 Use it in conjunction with the -n option to make sure you kill the right tinc daemon.
1487 Under native Windows the optional argument is ignored,
1488 the service will always be stopped and removed.
1490 @item -n, --net=@var{netname}
1491 Use configuration for net @var{netname}. @xref{Multiple networks}.
1493 @item -K, --generate-keys[=@var{bits}]
1494 Generate public/private keypair of @var{bits} length. If @var{bits} is not specified,
1495 1024 is the default. tinc will ask where you want to store the files,
1496 but will default to the configuration directory (you can use the -c or -n option
1497 in combination with -K). After that, tinc will quit.
1500 Lock tinc into main memory.
1501 This will prevent sensitive data like shared private keys to be written to the system swap files/partitions.
1503 @item --logfile[=@var{file}]
1504 Write log entries to a file instead of to the system logging facility.
1505 If @var{file} is omitted, the default is @file{@value{localstatedir}/log/tinc.@var{netname}.log}.
1507 @item --pidfile=@var{file}
1508 Write PID to @var{file} instead of @file{@value{localstatedir}/run/tinc.@var{netname}.pid}.
1510 @item --bypass-security
1511 Disables encryption and authentication.
1512 Only useful for debugging.
1515 Display a short reminder of these runtime options and terminate.
1518 Output version information and exit.
1522 @c ==================================================================
1527 You can also send the following signals to a running tincd process:
1533 Forces tinc to try to connect to all uplinks immediately.
1534 Usually tinc attempts to do this itself,
1535 but increases the time it waits between the attempts each time it failed,
1536 and if tinc didn't succeed to connect to an uplink the first time after it started,
1537 it defaults to the maximum time of 15 minutes.
1540 Partially rereads configuration files.
1541 Connections to hosts whose host config file are removed are closed.
1542 New outgoing connections specified in @file{tinc.conf} will be made.
1545 Temporarily increases debug level to 5.
1546 Send this signal again to revert to the original level.
1549 Dumps the connection list to syslog.
1552 Dumps virtual network device statistics, all known nodes, edges and subnets to syslog.
1555 Purges all information remembered about unreachable nodes.
1559 @c ==================================================================
1561 @section Debug levels
1563 @cindex debug levels
1564 The tinc daemon can send a lot of messages to the syslog.
1565 The higher the debug level, the more messages it will log.
1566 Each level inherits all messages of the previous level:
1572 This will log a message indicating tinc has started along with a version number.
1573 It will also log any serious error.
1576 This will log all connections that are made with other tinc daemons.
1579 This will log status and error messages from scripts and other tinc daemons.
1582 This will log all requests that are exchanged with other tinc daemons. These include
1583 authentication, key exchange and connection list updates.
1586 This will log a copy of everything received on the meta socket.
1589 This will log all network traffic over the virtual private network.
1593 @c ==================================================================
1594 @node Solving problems
1595 @section Solving problems
1597 If tinc starts without problems, but if the VPN doesn't work, you will have to find the cause of the problem.
1598 The first thing to do is to start tinc with a high debug level in the foreground,
1599 so you can directly see everything tinc logs:
1602 tincd -n @var{netname} -d5 -D
1605 If tinc does not log any error messages, then you might want to check the following things:
1608 @item @file{tinc-up} script
1609 Does this script contain the right commands?
1610 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.
1613 Does the Subnet (or Subnets) in the host configuration file of this host match the portion of the VPN that belongs to this host?
1615 @item Firewalls and NATs
1616 Do you have a firewall or a NAT device (a masquerading firewall or perhaps an ADSL router that performs masquerading)?
1617 If so, check that it allows TCP and UDP traffic on port 655.
1618 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.
1619 You can add @samp{TCPOnly = yes} to your host config file to force tinc to only use a single TCP connection,
1620 this works through most firewalls and NATs.
1625 @c ==================================================================
1626 @node Error messages
1627 @section Error messages
1629 What follows is a list of the most common error messages you might find in the logs.
1630 Some of them will only be visible if the debug level is high enough.
1633 @item Could not open /dev/tap0: No such device
1636 @item You forgot to `modprobe netlink_dev' or `modprobe ethertap'.
1637 @item You forgot to compile `Netlink device emulation' in the kernel.
1640 @item Can't write to /dev/net/tun: No such device
1643 @item You forgot to `modprobe tun'.
1644 @item You forgot to compile `Universal TUN/TAP driver' in the kernel.
1645 @item The tun device is located somewhere else in @file{/dev/}.
1648 @item Network address and prefix length do not match!
1651 @item The Subnet field must contain a @emph{network} address, trailing bits should be 0.
1652 @item If you only want to use one IP address, set the netmask to /32.
1655 @item Error reading RSA key file `rsa_key.priv': No such file or directory
1658 @item You forgot to create a public/private keypair.
1659 @item Specify the complete pathname to the private key file with the @samp{PrivateKeyFile} option.
1662 @item Warning: insecure file permissions for RSA private key file `rsa_key.priv'!
1665 @item The private key file is readable by users other than root.
1666 Use chmod to correct the file permissions.
1669 @item Creating metasocket failed: Address family not supported
1672 @item By default tinc tries to create both IPv4 and IPv6 sockets.
1673 On some platforms this might not be implemented.
1674 If the logs show @samp{Ready} later on, then at least one metasocket was created,
1675 and you can ignore this message.
1676 You can add @samp{AddressFamily = ipv4} to @file{tinc.conf} to prevent this from happening.
1679 @item Cannot route packet: unknown IPv4 destination 1.2.3.4
1682 @item You try to send traffic to a host on the VPN for which no Subnet is known.
1683 @item If it is a broadcast address (ending in .255), it probably is a samba server or a Windows host sending broadcast packets.
1687 @item Cannot route packet: ARP request for unknown address 1.2.3.4
1690 @item You try to send traffic to a host on the VPN for which no Subnet is known.
1693 @item Packet with destination 1.2.3.4 is looping back to us!
1696 @item Something is not configured right. Packets are being sent out to the
1697 virtual network device, but according to the Subnet directives in your host configuration
1698 file, those packets should go to your own host. Most common mistake is that
1699 you have a Subnet line in your host configuration file with a prefix length which is
1700 just as large as the prefix of the virtual network interface. The latter should in almost all
1701 cases be larger. Rethink your configuration.
1702 Note that you will only see this message if you specified a debug
1703 level of 5 or higher!
1704 @item Chances are that a @samp{Subnet = ...} line in the host configuration file of this tinc daemon is wrong.
1705 Change it to a subnet that is accepted locally by another interface,
1706 or if that is not the case, try changing the prefix length into /32.
1709 @item Node foo (1.2.3.4) is not reachable
1712 @item Node foo does not have a connection anymore, its tinc daemon is not running or its connection to the Internet is broken.
1715 @item Received UDP packet from unknown source 1.2.3.4 (port 12345)
1718 @item If you see this only sporadically, it is harmless and caused by a node sending packets using an old key.
1719 @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.
1720 You can add @samp{TCPOnly = yes} to host configuration files to force all VPN traffic to go over a TCP connection.
1723 @item Got bad/bogus/unauthorized REQUEST from foo (1.2.3.4 port 12345)
1726 @item Node foo does not have the right public/private keypair.
1727 Generate new keypairs and distribute them again.
1728 @item An attacker tries to gain access to your VPN.
1729 @item A network error caused corruption of metadata sent from foo.
1734 @c ==================================================================
1735 @node Sending bug reports
1736 @section Sending bug reports
1738 If you really can't find the cause of a problem, or if you suspect tinc is not working right,
1739 you can send us a bugreport, see @ref{Contact information}.
1740 Be sure to include the following information in your bugreport:
1743 @item A clear description of what you are trying to achieve and what the problem is.
1744 @item What platform (operating system, version, hardware architecture) and which version of tinc you use.
1745 @item If compiling tinc fails, a copy of @file{config.log} and the error messages you get.
1746 @item Otherwise, a copy of @file{tinc.conf}, @file{tinc-up} and all files in the @file{hosts/} directory.
1747 @item The output of the commands @samp{ifconfig -a} and @samp{route -n} (or @samp{netstat -rn} if that doesn't work).
1748 @item The output of any command that fails to work as it should (like ping or traceroute).
1751 @c ==================================================================
1752 @node Technical information
1753 @chapter Technical information
1758 * The meta-protocol::
1763 @c ==================================================================
1764 @node The connection
1765 @section The connection
1768 Tinc is a daemon that takes VPN data and transmit that to another host
1769 computer over the existing Internet infrastructure.
1773 * The meta-connection::
1777 @c ==================================================================
1778 @node The UDP tunnel
1779 @subsection The UDP tunnel
1781 @cindex virtual network device
1783 The data itself is read from a character device file, the so-called
1784 @emph{virtual network device}. This device is associated with a network
1785 interface. Any data sent to this interface can be read from the device,
1786 and any data written to the device gets sent from the interface.
1787 There are two possible types of virtual network devices:
1788 `tun' style, which are point-to-point devices which can only handle IPv4 and/or IPv6 packets,
1789 and `tap' style, which are Ethernet devices and handle complete Ethernet frames.
1791 So when tinc reads an Ethernet frame from the device, it determines its
1792 type. When tinc is in it's default routing mode, it can handle IPv4 and IPv6
1793 packets. Depending on the Subnet lines, it will send the packets off to their destination IP address.
1794 In the `switch' and `hub' mode, tinc will use broadcasts and MAC address discovery
1795 to deduce the destination of the packets.
1796 Since the latter modes only depend on the link layer information,
1797 any protocol that runs over Ethernet is supported (for instance IPX and Appletalk).
1798 However, only `tap' style devices provide this information.
1800 After the destination has been determined,
1801 the packet will be compressed (optionally),
1802 a sequence number will be added to the packet,
1803 the packet will then be encrypted
1804 and a message authentication code will be appended.
1806 @cindex encapsulating
1808 When that is done, time has come to actually transport the
1809 packet to the destination computer. We do this by sending the packet
1810 over an UDP connection to the destination host. This is called
1811 @emph{encapsulating}, the VPN packet (though now encrypted) is
1812 encapsulated in another IP datagram.
1814 When the destination receives this packet, the same thing happens, only
1815 in reverse. So it checks the message authentication code, decrypts the contents of the UDP datagram,
1816 checks the sequence number
1817 and writes the decrypted information to its own virtual network device.
1819 If the virtual network device is a `tun' device (a point-to-point tunnel),
1820 there is no problem for the kernel to accept a packet.
1821 However, if it is a `tap' device (this is the only available type on FreeBSD),
1822 the destination MAC address must match that of the virtual network interface.
1823 If tinc is in it's default routing mode, ARP does not work, so the correct destination MAC
1824 can not be known by the sending host.
1825 Tinc solves this by letting the receiving end detect the MAC address of its own virtual network interface
1826 and overwriting the destination MAC address of the received packet.
1828 In switch or hub modes ARP does work so the sender already knows the correct destination MAC address.
1829 In those modes every interface should have a unique MAC address, so make sure they are not the same.
1830 Because switch and hub modes rely on MAC addresses to function correctly,
1831 these modes cannot be used on the following operating systems which don't have a `tap' style virtual network device:
1832 OpenBSD, NetBSD, Darwin and Solaris.
1835 @c ==================================================================
1836 @node The meta-connection
1837 @subsection The meta-connection
1839 Having only a UDP connection available is not enough. Though suitable
1840 for transmitting data, we want to be able to reliably send other
1841 information, such as routing and session key information to somebody.
1844 TCP is a better alternative, because it already contains protection
1845 against information being lost, unlike UDP.
1847 So we establish two connections. One for the encrypted VPN data, and one
1848 for other information, the meta-data. Hence, we call the second
1849 connection the meta-connection. We can now be sure that the
1850 meta-information doesn't get lost on the way to another computer.
1852 @cindex data-protocol
1853 @cindex meta-protocol
1854 Like with any communication, we must have a protocol, so that everybody
1855 knows what everything stands for, and how she should react. Because we
1856 have two connections, we also have two protocols. The protocol used for
1857 the UDP data is the ``data-protocol,'' the other one is the
1860 The reason we don't use TCP for both protocols is that UDP is much
1861 better for encapsulation, even while it is less reliable. The real
1862 problem is that when TCP would be used to encapsulate a TCP stream
1863 that's on the private network, for every packet sent there would be
1864 three ACKs sent instead of just one. Furthermore, if there would be
1865 a timeout, both TCP streams would sense the timeout, and both would
1866 start re-sending packets.
1869 @c ==================================================================
1870 @node The meta-protocol
1871 @section The meta-protocol
1873 The meta protocol is used to tie all tinc daemons together, and
1874 exchange information about which tinc daemon serves which virtual
1877 The meta protocol consists of requests that can be sent to the other
1878 side. Each request has a unique number and several parameters. All
1879 requests are represented in the standard ASCII character set. It is
1880 possible to use tools such as telnet or netcat to connect to a tinc
1881 daemon started with the --bypass-security option
1882 and to read and write requests by hand, provided that one
1883 understands the numeric codes sent.
1885 The authentication scheme is described in @ref{Authentication protocol}. After a
1886 successful authentication, the server and the client will exchange all the
1887 information about other tinc daemons and subnets they know of, so that both
1888 sides (and all the other tinc daemons behind them) have their information
1895 ------------------------------------------------------------------
1896 ADD_EDGE node1 node2 21.32.43.54 655 222 0
1897 | | | | | +-> options
1898 | | | | +----> weight
1899 | | | +--------> UDP port of node2
1900 | | +----------------> real address of node2
1901 | +-------------------------> name of destination node
1902 +-------------------------------> name of source node
1904 ADD_SUBNET node 192.168.1.0/24
1905 | | +--> prefixlength
1906 | +--------> network address
1907 +------------------> owner of this subnet
1908 ------------------------------------------------------------------
1911 The ADD_EDGE messages are to inform other tinc daemons that a connection between
1912 two nodes exist. The address of the destination node is available so that
1913 VPN packets can be sent directly to that node.
1915 The ADD_SUBNET messages inform other tinc daemons that certain subnets belong
1916 to certain nodes. tinc will use it to determine to which node a VPN packet has
1923 ------------------------------------------------------------------
1924 DEL_EDGE node1 node2
1925 | +----> name of destination node
1926 +----------> name of source node
1928 DEL_SUBNET node 192.168.1.0/24
1929 | | +--> prefixlength
1930 | +--------> network address
1931 +------------------> owner of this subnet
1932 ------------------------------------------------------------------
1935 In case a connection between two daemons is closed or broken, DEL_EDGE messages
1936 are sent to inform the other daemons of that fact. Each daemon will calculate a
1937 new route to the the daemons, or mark them unreachable if there isn't any.
1944 ------------------------------------------------------------------
1945 REQ_KEY origin destination
1946 | +--> name of the tinc daemon it wants the key from
1947 +----------> name of the daemon that wants the key
1949 ANS_KEY origin destination 4ae0b0a82d6e0078 91 64 4
1950 | | \______________/ | | +--> MAC length
1951 | | | | +-----> digest algorithm
1952 | | | +--------> cipher algorithm
1953 | | +--> 128 bits key
1954 | +--> name of the daemon that wants the key
1955 +----------> name of the daemon that uses this key
1958 +--> daemon that has changed it's packet key
1959 ------------------------------------------------------------------
1962 The keys used to encrypt VPN packets are not sent out directly. This is
1963 because it would generate a lot of traffic on VPNs with many daemons, and
1964 chances are that not every tinc daemon will ever send a packet to every
1965 other daemon. Instead, if a daemon needs a key it sends a request for it
1966 via the meta connection of the nearest hop in the direction of the
1973 ------------------------------------------------------------------
1976 ------------------------------------------------------------------
1979 There is also a mechanism to check if hosts are still alive. Since network
1980 failures or a crash can cause a daemon to be killed without properly
1981 shutting down the TCP connection, this is necessary to keep an up to date
1982 connection list. PINGs are sent at regular intervals, except when there
1983 is also some other traffic. A little bit of salt (random data) is added
1984 with each PING and PONG message, to make sure that long sequences of PING/PONG
1985 messages without any other traffic won't result in known plaintext.
1987 This basically covers what is sent over the meta connection by tinc.
1990 @c ==================================================================
1996 Tinc got its name from ``TINC,'' short for @emph{There Is No Cabal}; the
1997 alleged Cabal was/is an organisation that was said to keep an eye on the
1998 entire Internet. As this is exactly what you @emph{don't} want, we named
1999 the tinc project after TINC.
2002 But in order to be ``immune'' to eavesdropping, you'll have to encrypt
2003 your data. Because tinc is a @emph{Secure} VPN (SVPN) daemon, it does
2004 exactly that: encrypt.
2005 Tinc by default uses blowfish encryption with 128 bit keys in CBC mode, 32 bit
2006 sequence numbers and 4 byte long message authentication codes to make sure
2007 eavesdroppers cannot get and cannot change any information at all from the
2008 packets they can intercept. The encryption algorithm and message authentication
2009 algorithm can be changed in the configuration. The length of the message
2010 authentication codes is also adjustable. The length of the key for the
2011 encryption algorithm is always the default length used by OpenSSL.
2014 * Authentication protocol::
2015 * Encryption of network packets::
2020 @c ==================================================================
2021 @node Authentication protocol
2022 @subsection Authentication protocol
2024 @cindex authentication
2025 A new scheme for authentication in tinc has been devised, which offers some
2026 improvements over the protocol used in 1.0pre2 and 1.0pre3. Explanation is
2036 --------------------------------------------------------------------------
2037 client <attempts connection>
2039 server <accepts connection>
2043 +-------> name of tinc daemon
2047 +-------> name of tinc daemon
2049 client META_KEY 5f0823a93e35b69e...7086ec7866ce582b
2050 \_________________________________/
2051 +-> RSAKEYLEN bits totally random string S1,
2052 encrypted with server's public RSA key
2054 server META_KEY 6ab9c1640388f8f0...45d1a07f8a672630
2055 \_________________________________/
2056 +-> RSAKEYLEN bits totally random string S2,
2057 encrypted with client's public RSA key
2060 - the client will symmetrically encrypt outgoing traffic using S1
2061 - the server will symmetrically encrypt outgoing traffic using S2
2063 client CHALLENGE da02add1817c1920989ba6ae2a49cecbda0
2064 \_________________________________/
2065 +-> CHALLEN bits totally random string H1
2067 server CHALLENGE 57fb4b2ccd70d6bb35a64c142f47e61d57f
2068 \_________________________________/
2069 +-> CHALLEN bits totally random string H2
2071 client CHAL_REPLY 816a86
2072 +-> 160 bits SHA1 of H2
2074 server CHAL_REPLY 928ffe
2075 +-> 160 bits SHA1 of H1
2077 After the correct challenge replies are received, both ends have proved
2078 their identity. Further information is exchanged.
2080 client ACK 655 123 0
2082 | +----> estimated weight
2083 +--------> listening port of client
2085 server ACK 655 321 0
2087 | +----> estimated weight
2088 +--------> listening port of server
2089 --------------------------------------------------------------------------
2092 This new scheme has several improvements, both in efficiency and security.
2094 First of all, the server sends exactly the same kind of messages over the wire
2095 as the client. The previous versions of tinc first authenticated the client,
2096 and then the server. This scheme even allows both sides to send their messages
2097 simultaneously, there is no need to wait for the other to send something first.
2098 This means that any calculations that need to be done upon sending or receiving
2099 a message can also be done in parallel. This is especially important when doing
2100 RSA encryption/decryption. Given that these calculations are the main part of
2101 the CPU time spent for the authentication, speed is improved by a factor 2.
2103 Second, only one RSA encrypted message is sent instead of two. This reduces the
2104 amount of information attackers can see (and thus use for a cryptographic
2105 attack). It also improves speed by a factor two, making the total speedup a
2108 Third, and most important:
2109 The symmetric cipher keys are exchanged first, the challenge is done
2110 afterwards. In the previous authentication scheme, because a man-in-the-middle
2111 could pass the challenge/chal_reply phase (by just copying the messages between
2112 the two real tinc daemons), but no information was exchanged that was really
2113 needed to read the rest of the messages, the challenge/chal_reply phase was of
2114 no real use. The man-in-the-middle was only stopped by the fact that only after
2115 the ACK messages were encrypted with the symmetric cipher. Potentially, it
2116 could even send it's own symmetric key to the server (if it knew the server's
2117 public key) and read some of the metadata the server would send it (it was
2118 impossible for the mitm to read actual network packets though). The new scheme
2119 however prevents this.
2121 This new scheme makes sure that first of all, symmetric keys are exchanged. The
2122 rest of the messages are then encrypted with the symmetric cipher. Then, each
2123 side can only read received messages if they have their private key. The
2124 challenge is there to let the other side know that the private key is really
2125 known, because a challenge reply can only be sent back if the challenge is
2126 decrypted correctly, and that can only be done with knowledge of the private
2129 Fourth: the first thing that is sent via the symmetric cipher encrypted
2130 connection is a totally random string, so that there is no known plaintext (for
2131 an attacker) in the beginning of the encrypted stream.
2134 @c ==================================================================
2135 @node Encryption of network packets
2136 @subsection Encryption of network packets
2139 A data packet can only be sent if the encryption key is known to both
2140 parties, and the connection is activated. If the encryption key is not
2141 known, a request is sent to the destination using the meta connection
2142 to retrieve it. The packet is stored in a queue while waiting for the
2146 The UDP packet containing the network packet from the VPN has the following layout:
2149 ... | IP header | UDP header | seqno | VPN packet | MAC | UDP trailer
2150 \___________________/\_____/
2152 V +---> digest algorithm
2153 Encrypted with symmetric cipher
2156 So, the entire VPN packet is encrypted using a symmetric cipher, including a 32 bits
2157 sequence number that is added in front of the actual VPN packet, to act as a unique
2158 IV for each packet and to prevent replay attacks. A message authentication code
2159 is added to the UDP packet to prevent alteration of packets. By default the
2160 first 4 bytes of the digest are used for this, but this can be changed using
2161 the MACLength configuration variable.
2163 @c ==================================================================
2164 @node Security issues
2165 @subsection Security issues
2167 In August 2000, we discovered the existence of a security hole in all versions
2168 of tinc up to and including 1.0pre2. This had to do with the way we exchanged
2169 keys. Since then, we have been working on a new authentication scheme to make
2170 tinc as secure as possible. The current version uses the OpenSSL library and
2171 uses strong authentication with RSA keys.
2173 On the 29th of December 2001, Jerome Etienne posted a security analysis of tinc
2174 1.0pre4. Due to a lack of sequence numbers and a message authentication code
2175 for each packet, an attacker could possibly disrupt certain network services or
2176 launch a denial of service attack by replaying intercepted packets. The current
2177 version adds sequence numbers and message authentication codes to prevent such
2180 On the 15th of September 2003, Peter Gutmann posted a security analysis of tinc
2181 1.0.1. He argues that the 32 bit sequence number used by tinc is not a good IV,
2182 that tinc's default length of 4 bytes for the MAC is too short, and he doesn't
2183 like tinc's use of RSA during authentication. We do not know of a security hole
2184 in this version of tinc, but tinc's security is not as strong as TLS or IPsec.
2185 We will address these issues in tinc 2.0.
2187 Cryptography is a hard thing to get right. We cannot make any
2188 guarantees. Time, review and feedback are the only things that can
2189 prove the security of any cryptographic product. If you wish to review
2190 tinc or give us feedback, you are stronly encouraged to do so.
2193 @c ==================================================================
2194 @node Platform specific information
2195 @chapter Platform specific information
2198 * Interface configuration::
2202 @c ==================================================================
2203 @node Interface configuration
2204 @section Interface configuration
2206 When configuring an interface, one normally assigns it an address and a
2207 netmask. The address uniquely identifies the host on the network attached to
2208 the interface. The netmask, combined with the address, forms a subnet. It is
2209 used to add a route to the routing table instructing the kernel to send all
2210 packets which fall into that subnet to that interface. Because all packets for
2211 the entire VPN should go to the virtual network interface used by tinc, the
2212 netmask should be such that it encompasses the entire VPN.
2216 @multitable {Darwin (MacOS/X)} {ifconfig route add -bla network address netmask netmask prefixlength interface}
2218 @tab @code{ifconfig} @var{interface} @var{address} @code{netmask} @var{netmask}
2219 @item Linux iproute2
2220 @tab @code{ip addr add} @var{address}@code{/}@var{prefixlength} @code{dev} @var{interface}
2222 @tab @code{ifconfig} @var{interface} @var{address} @code{netmask} @var{netmask}
2224 @tab @code{ifconfig} @var{interface} @var{address} @code{netmask} @var{netmask}
2226 @tab @code{ifconfig} @var{interface} @var{address} @code{netmask} @var{netmask}
2228 @tab @code{ifconfig} @var{interface} @var{address} @code{netmask} @var{netmask}
2229 @item Darwin (MacOS/X)
2230 @tab @code{ifconfig} @var{interface} @var{address} @code{netmask} @var{netmask}
2232 @tab @code{netsh interface ip set address} @var{interface} @code{static} @var{address} @var{netmask}
2238 @multitable {Darwin (MacOS/X)} {ifconfig route add -bla network address netmask netmask prefixlength interface}
2240 @tab @code{ifconfig} @var{interface} @code{add} @var{address}@code{/}@var{prefixlength}
2242 @tab @code{ifconfig} @var{interface} @code{inet6} @var{address} @code{prefixlen} @var{prefixlength}
2244 @tab @code{ifconfig} @var{interface} @code{inet6} @var{address} @code{prefixlen} @var{prefixlength}
2246 @tab @code{ifconfig} @var{interface} @code{inet6} @var{address} @code{prefixlen} @var{prefixlength}
2248 @tab @code{ifconfig} @var{interface} @code{inet6 plumb up}
2250 @tab @code{ifconfig} @var{interface} @code{inet6 addif} @var{address} @var{address}
2251 @item Darwin (MacOS/X)
2252 @tab @code{ifconfig} @var{interface} @code{inet6} @var{address} @code{prefixlen} @var{prefixlength}
2254 @tab @code{netsh interface ipv6 add address} @var{interface} @code{static} @var{address}/@var{prefixlength}
2258 @c ==================================================================
2262 In some cases it might be necessary to add more routes to the virtual network
2263 interface. There are two ways to indicate which interface a packet should go
2264 to, one is to use the name of the interface itself, another way is to specify
2265 the (local) address that is assigned to that interface (@var{local_address}). The
2266 former way is unambiguous and therefore preferable, but not all platforms
2269 Adding routes to IPv4 subnets:
2271 @multitable {Darwin (MacOS/X)} {ifconfig route add -bla network address netmask netmask prefixlength interface}
2273 @tab @code{route add -net} @var{network_address} @code{netmask} @var{netmask} @var{interface}
2274 @item Linux iproute2
2275 @tab @code{ip route add} @var{network_address}@code{/}@var{prefixlength} @code{dev} @var{interface}
2277 @tab @code{route add} @var{network_address}@code{/}@var{prefixlength} @var{local_address}
2279 @tab @code{route add} @var{network_address}@code{/}@var{prefixlength} @var{local_address}
2281 @tab @code{route add} @var{network_address}@code{/}@var{prefixlength} @var{local_address}
2283 @tab @code{route add} @var{network_address}@code{/}@var{prefixlength} @var{local_address} @code{-interface}
2284 @item Darwin (MacOS/X)
2285 @tab @code{route add} @var{network_address}@code{/}@var{prefixlength} @var{local_address}
2287 @tab @code{netsh routing ip add persistentroute} @var{network_address} @var{netmask} @var{interface} @var{local_address}
2290 Adding routes to IPv6 subnets:
2292 @multitable {Darwin (MacOS/X)} {ifconfig route add -bla network address netmask netmask prefixlength interface}
2294 @tab @code{route add -A inet6} @var{network_address}@code{/}@var{prefixlength} @var{interface}
2295 @item Linux iproute2
2296 @tab @code{ip route add} @var{network_address}@code{/}@var{prefixlength} @code{dev} @var{interface}
2298 @tab @code{route add -inet6} @var{network_address}@code{/}@var{prefixlength} @var{local_address}
2300 @tab @code{route add -inet6} @var{network_address} @var{local_address} @code{-prefixlen} @var{prefixlength}
2302 @tab @code{route add -inet6} @var{network_address} @var{local_address} @code{-prefixlen} @var{prefixlength}
2304 @tab @code{route add -inet6} @var{network_address}@code{/}@var{prefixlength} @var{local_address} @code{-interface}
2305 @item Darwin (MacOS/X)
2308 @tab @code{netsh interface ipv6 add route} @var{network address}/@var{prefixlength} @var{interface}
2312 @c ==================================================================
2318 * Contact information::
2323 @c ==================================================================
2324 @node Contact information
2325 @section Contact information
2328 Tinc's website is at @url{http://www.tinc-vpn.org/},
2329 this server is located in the Netherlands.
2332 We have an IRC channel on the FreeNode and OFTC IRC networks. Connect to
2333 @uref{http://www.freenode.net/, irc.freenode.net}
2335 @uref{http://www.oftc.net/, irc.oftc.net}
2336 and join channel #tinc.
2339 @c ==================================================================
2344 @item Ivo Timmermans (zarq) (@email{ivo@@tinc-vpn.org})
2345 @item Guus Sliepen (guus) (@email{guus@@tinc-vpn.org})
2348 We have received a lot of valuable input from users. With their help,
2349 tinc has become the flexible and robust tool that it is today. We have
2350 composed a list of contributions, in the file called @file{THANKS} in
2351 the source distribution.
2354 @c ==================================================================
2356 @unnumbered Concept Index
2358 @c ==================================================================
2362 @c ==================================================================
projects / oweals / tinc.git / blob