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{} 1998-2011 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{} 1998-2011 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 Using tap devices is recommended.
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.
279 @c ==================================================================
280 @node Configuration of NetBSD kernels
281 @subsection Configuration of NetBSD kernels
283 For NetBSD version 1.5.2 and higher,
284 the tun driver is included in the default kernel configuration.
286 Tunneling IPv6 may not work on NetBSD's tun device.
289 @c ==================================================================
290 @node Configuration of Solaris kernels
291 @subsection Configuration of Solaris kernels
293 For Solaris 8 (SunOS 5.8) and higher,
294 the tun driver may or may not be included in the default kernel configuration.
295 If it isn't, the source can be downloaded from @uref{http://vtun.sourceforge.net/tun/}.
296 For x86 and sparc64 architectures, precompiled versions can be found at @uref{http://www.monkey.org/~dugsong/fragroute/}.
297 If the @file{net/if_tun.h} header file is missing, install it from the source package.
300 @c ==================================================================
301 @node Configuration of Darwin (MacOS/X) kernels
302 @subsection Configuration of Darwin (MacOS/X) kernels
304 Tinc on Darwin relies on a tunnel driver for its data acquisition from the kernel.
305 Tinc supports either the driver from @uref{http://tuntaposx.sourceforge.net/},
306 which supports both tun and tap style devices,
307 and also the driver from from @uref{http://chrisp.de/en/projects/tunnel.html}.
308 The former driver is recommended.
309 The tunnel driver must be loaded before starting tinc with the following command:
316 @c ==================================================================
317 @node Configuration of Windows
318 @subsection Configuration of Windows
320 You will need to install the latest TAP-Win32 driver from OpenVPN.
321 You can download it from @uref{http://openvpn.sourceforge.net}.
322 Using the Network Connections control panel,
323 configure the TAP-Win32 network interface in the same way as you would do from the tinc-up script,
324 as explained in the rest of the documentation.
327 @c ==================================================================
333 Before you can configure or build tinc, you need to have the OpenSSL,
334 zlib and lzo libraries installed on your system. If you try to configure tinc without
335 having them installed, configure will give you an error message, and stop.
345 @c ==================================================================
350 For all cryptography-related functions, tinc uses the functions provided
351 by the OpenSSL library.
353 If this library is not installed, you wil get an error when configuring
354 tinc for build. Support for running tinc without having OpenSSL
355 installed @emph{may} be added in the future.
357 You can use your operating system's package manager to install this if
358 available. Make sure you install the development AND runtime versions
361 If you have to install OpenSSL manually, you can get the source code
362 from @url{http://www.openssl.org/}. Instructions on how to configure,
363 build and install this package are included within the package. Please
364 make sure you build development and runtime libraries (which is the
367 If you installed the OpenSSL libraries from source, it may be necessary
368 to let configure know where they are, by passing configure one of the
369 --with-openssl-* parameters.
372 --with-openssl=DIR OpenSSL library and headers prefix
373 --with-openssl-include=DIR OpenSSL headers directory
374 (Default is OPENSSL_DIR/include)
375 --with-openssl-lib=DIR OpenSSL library directory
376 (Default is OPENSSL_DIR/lib)
380 @subsubheading License
383 The complete source code of tinc is covered by the GNU GPL version 2.
384 Since the license under which OpenSSL is distributed is not directly
385 compatible with the terms of the GNU GPL
386 @uref{http://www.openssl.org/support/faq.html#LEGAL2}, we
387 include an exemption to the GPL (see also the file COPYING.README) to allow
388 everyone to create a statically or dynamically linked executable:
391 This program is released under the GPL with the additional exemption
392 that compiling, linking, and/or using OpenSSL is allowed. You may
393 provide binary packages linked to the OpenSSL libraries, provided that
394 all other requirements of the GPL are met.
397 Since the LZO library used by tinc is also covered by the GPL,
398 we also present the following exemption:
401 Hereby I grant a special exception to the tinc VPN project
402 (http://www.tinc-vpn.org/) to link the LZO library with the OpenSSL library
403 (http://www.openssl.org).
405 Markus F.X.J. Oberhumer
409 @c ==================================================================
414 For the optional compression of UDP packets, tinc uses the functions provided
417 If this library is not installed, you wil get an error when configuring
418 tinc for build. Support for running tinc without having zlib
419 installed @emph{may} be added in the future.
421 You can use your operating system's package manager to install this if
422 available. Make sure you install the development AND runtime versions
425 If you have to install zlib manually, you can get the source code
426 from @url{http://www.gzip.org/zlib/}. Instructions on how to configure,
427 build and install this package are included within the package. Please
428 make sure you build development and runtime libraries (which is the
432 @c ==================================================================
437 Another form of compression is offered using the lzo library.
439 If this library is not installed, you wil get an error when configuring
440 tinc for build. Support for running tinc without having lzo
441 installed @emph{may} be added in the future.
443 You can use your operating system's package manager to install this if
444 available. Make sure you install the development AND runtime versions
447 If you have to install lzo manually, you can get the source code
448 from @url{http://www.oberhumer.com/opensource/lzo/}. Instructions on how to configure,
449 build and install this package are included within the package. Please
450 make sure you build development and runtime libraries (which is the
454 @c ==================================================================
459 For the main event loop, tinc uses the libevent library.
461 If this library is not installed, you wil get an error when configuring
464 You can use your operating system's package manager to install this if
465 available. Make sure you install the development AND runtime versions
468 If you have to install libevent manually, you can get the source code
469 from @url{http://monkey.org/~provos/libevent/}. Instructions on how to configure,
470 build and install this package are included within the package. Please
471 make sure you build development and runtime libraries (which is the
484 @c ==================================================================
486 @chapter Installation
488 If you use Debian, you may want to install one of the
489 precompiled packages for your system. These packages are equipped with
490 system startup scripts and sample configurations.
492 If you cannot use one of the precompiled packages, or you want to compile tinc
493 for yourself, you can use the source. The source is distributed under
494 the GNU General Public License (GPL). Download the source from the
495 @uref{http://www.tinc-vpn.org/download, download page}, which has
496 the checksums of these files listed; you may wish to check these with
497 md5sum before continuing.
499 Tinc comes in a convenient autoconf/automake package, which you can just
500 treat the same as any other package. Which is just untar it, type
501 `./configure' and then `make'.
502 More detailed instructions are in the file @file{INSTALL}, which is
503 included in the source distribution.
506 * Building and installing tinc::
511 @c ==================================================================
512 @node Building and installing tinc
513 @section Building and installing tinc
515 Detailed instructions on configuring the source, building tinc and installing tinc
516 can be found in the file called @file{INSTALL}.
518 @cindex binary package
519 If you happen to have a binary package for tinc for your distribution,
520 you can use the package management tools of that distribution to install tinc.
521 The documentation that comes along with your distribution will tell you how to do that.
524 * Darwin (MacOS/X) build environment::
525 * Cygwin (Windows) build environment::
526 * MinGW (Windows) build environment::
530 @c ==================================================================
531 @node Darwin (MacOS/X) build environment
532 @subsection Darwin (MacOS/X) build environment
534 In order to build tinc on Darwin, you need to install the MacOS/X Developer Tools
535 from @uref{http://developer.apple.com/tools/macosxtools.html} and
536 a recent version of Fink from @uref{http://fink.sourceforge.net/}.
538 After installation use fink to download and install the following packages:
539 autoconf25, automake, dlcompat, m4, openssl, zlib and lzo.
541 @c ==================================================================
542 @node Cygwin (Windows) build environment
543 @subsection Cygwin (Windows) build environment
545 If Cygwin hasn't already been installed, install it directly from
546 @uref{http://www.cygwin.com/}.
548 When tinc is compiled in a Cygwin environment, it can only be run in this environment,
549 but all programs, including those started outside the Cygwin environment, will be able to use the VPN.
550 It will also support all features.
552 @c ==================================================================
553 @node MinGW (Windows) build environment
554 @subsection MinGW (Windows) build environment
556 You will need to install the MinGW environment from @uref{http://www.mingw.org}.
558 When tinc is compiled using MinGW it runs natively under Windows,
559 it is not necessary to keep MinGW installed.
561 When detaching, tinc will install itself as a service,
562 which will be restarted automatically after reboots.
565 @c ==================================================================
567 @section System files
569 Before you can run tinc, you must make sure you have all the needed
570 files on your system.
578 @c ==================================================================
580 @subsection Device files
583 Most operating systems nowadays come with the necessary device files by default,
584 or they have a mechanism to create them on demand.
586 If you use Linux and do not have udev installed,
587 you may need to create the following device file if it does not exist:
590 mknod -m 600 /dev/net/tun c 10 200
594 @c ==================================================================
596 @subsection Other files
598 @subsubheading @file{/etc/networks}
600 You may add a line to @file{/etc/networks} so that your VPN will get a
601 symbolic name. For example:
607 @subsubheading @file{/etc/services}
610 You may add this line to @file{/etc/services}. The effect is that you
611 may supply a @samp{tinc} as a valid port number to some programs. The
612 number 655 is registered with the IANA.
617 # Ivo Timmermans <ivo@@tinc-vpn.org>
632 @c ==================================================================
634 @chapter Configuration
637 * Configuration introduction::
638 * Multiple networks::
639 * How connections work::
640 * Configuration files::
641 * Generating keypairs::
642 * Network interfaces::
643 * Example configuration::
646 @c ==================================================================
647 @node Configuration introduction
648 @section Configuration introduction
650 Before actually starting to configure tinc and editing files,
651 make sure you have read this entire section so you know what to expect.
652 Then, make it clear to yourself how you want to organize your VPN:
653 What are the nodes (computers running tinc)?
654 What IP addresses/subnets do they have?
655 What is the network mask of the entire VPN?
656 Do you need special firewall rules?
657 Do you have to set up masquerading or forwarding rules?
658 Do you want to run tinc in router mode or switch mode?
659 These questions can only be answered by yourself,
660 you will not find the answers in this documentation.
661 Make sure you have an adequate understanding of networks in general.
662 @cindex Network Administrators Guide
663 A good resource on networking is the
664 @uref{http://www.linuxdoc.org/LDP/nag2/, Linux Network Administrators Guide}.
666 If you have everything clearly pictured in your mind,
667 proceed in the following order:
668 First, generate the configuration files (@file{tinc.conf}, your host configuration file, @file{tinc-up} and perhaps @file{tinc-down}).
669 Then generate the keypairs.
670 Finally, distribute the host configuration files.
671 These steps are described in the subsections below.
674 @c ==================================================================
675 @node Multiple networks
676 @section Multiple networks
678 @cindex multiple networks
680 In order to allow you to run more than one tinc daemon on one computer,
681 for instance if your computer is part of more than one VPN,
682 you can assign a @var{netname} to your VPN.
683 It is not required if you only run one tinc daemon,
684 it doesn't even have to be the same on all the sites of your VPN,
685 but it is recommended that you choose one anyway.
687 We will asume you use a netname throughout this document.
688 This means that you call tincd with the -n argument,
689 which will assign a netname to this daemon.
691 The effect of this is that the daemon will set its configuration
692 root to @file{@value{sysconfdir}/tinc/@var{netname}/}, where @var{netname} is your argument to the -n
693 option. You'll notice that it appears in syslog as @file{tinc.@var{netname}}.
695 However, it is not strictly necessary that you call tinc with the -n
696 option. In this case, the network name would just be empty, and it will
697 be used as such. tinc now looks for files in @file{@value{sysconfdir}/tinc/}, instead of
698 @file{@value{sysconfdir}/tinc/@var{netname}/}; the configuration file should be @file{@value{sysconfdir}/tinc/tinc.conf},
699 and the host configuration files are now expected to be in @file{@value{sysconfdir}/tinc/hosts/}.
701 But it is highly recommended that you use this feature of tinc, because
702 it will be so much clearer whom your daemon talks to. Hence, we will
703 assume that you use it.
706 @c ==================================================================
707 @node How connections work
708 @section How connections work
710 When tinc starts up, it parses the command-line options and then
711 reads in the configuration file tinc.conf.
712 If it sees one or more `ConnectTo' values pointing to other tinc daemons in that file,
713 it will try to connect to those other daemons.
714 Whether this succeeds or not and whether `ConnectTo' is specified or not,
715 tinc will listen for incoming connection from other deamons.
716 If you did specify a `ConnectTo' value and the other side is not responding,
717 tinc will keep retrying.
718 This means that once started, tinc will stay running until you tell it to stop,
719 and failures to connect to other tinc daemons will not stop your tinc daemon
720 for trying again later.
721 This means you don't have to intervene if there are temporary network problems.
725 There is no real distinction between a server and a client in tinc.
726 If you wish, you can view a tinc daemon without a `ConnectTo' value as a server,
727 and one which does specify such a value as a client.
728 It does not matter if two tinc daemons have a `ConnectTo' value pointing to each other however.
731 @c ==================================================================
732 @node Configuration files
733 @section Configuration files
735 The actual configuration of the daemon is done in the file
736 @file{@value{sysconfdir}/tinc/@var{netname}/tinc.conf} and at least one other file in the directory
737 @file{@value{sysconfdir}/tinc/@var{netname}/hosts/}.
739 These file consists of comments (lines started with a #) or assignments
746 The variable names are case insensitive, and any spaces, tabs, newlines
747 and carriage returns are ignored. Note: it is not required that you put
748 in the `=' sign, but doing so improves readability. If you leave it
749 out, remember to replace it with at least one space character.
751 The server configuration is complemented with host specific configuration (see
752 the next section). Although all host configuration options for the local node
753 listed in this document can also be put in
754 @file{@value{sysconfdir}/tinc/@var{netname}/tinc.conf}, it is recommended to
755 put host specific configuration options in the host configuration file, as this
756 makes it easy to exchange with other nodes.
758 In this section all valid variables are listed in alphabetical order.
759 The default value is given between parentheses,
760 other comments are between square brackets.
763 * Main configuration variables::
764 * Host configuration variables::
770 @c ==================================================================
771 @node Main configuration variables
772 @subsection Main configuration variables
775 @cindex AddressFamily
776 @item AddressFamily = <ipv4|ipv6|any> (any)
777 This option affects the address family of listening and outgoing sockets.
778 If any is selected, then depending on the operating system
779 both IPv4 and IPv6 or just IPv6 listening sockets will be created.
781 @cindex BindToAddress
782 @item BindToAddress = <@var{address}> [experimental]
783 If your computer has more than one IPv4 or IPv6 address, tinc
784 will by default listen on all of them for incoming connections.
785 Multiple BindToAddress variables may be specified,
786 in which case listening sockets for each specified address are made.
788 This option may not work on all platforms.
790 @cindex BindToInterface
791 @item BindToInterface = <@var{interface}> [experimental]
792 If you have more than one network interface in your computer, tinc will
793 by default listen on all of them for incoming connections. It is
794 possible to bind tinc to a single interface like eth0 or ppp0 with this
797 This option may not work on all platforms.
800 @item Broadcast = <yes | no> (yes) [experimental]
801 When disabled, tinc will drop all broadcast and multicast packets, in both router and switch mode.
804 @item ConnectTo = <@var{name}>
805 Specifies which other tinc daemon to connect to on startup.
806 Multiple ConnectTo variables may be specified,
807 in which case outgoing connections to each specified tinc daemon are made.
808 The names should be known to this tinc daemon
809 (i.e., there should be a host configuration file for the name on the ConnectTo line).
811 If you don't specify a host with ConnectTo,
812 tinc won't try to connect to other daemons at all,
813 and will instead just listen for incoming connections.
816 @item DecrementTTL = <yes | no> (yes)
817 When enabled, tinc will decrement the Time To Live field in IPv4 packets, or the Hop Limit field in IPv6 packets,
818 before forwarding a received packet to the virtual network device or to another node,
819 and will drop packets that have a TTL value of zero,
820 in which case it will send an ICMP Time Exceeded packet back.
823 @item Device = <@var{device}> (@file{/dev/tap0}, @file{/dev/net/tun} or other depending on platform)
824 The virtual network device to use.
825 Tinc will automatically detect what kind of device it is.
826 Note that you can only use one device per daemon.
827 Under Windows, use @var{Interface} instead of @var{Device}.
828 Note that you can only use one device per daemon.
829 See also @ref{Device files}.
832 @item DeviceType = <@var{type}> (platform dependent)
833 The type of the virtual network device.
834 Tinc will normally automatically select the right type of tun/tap interface, and this option should not be used.
835 However, this option can be used to select one of the special interface types, if support for them is compiled in.
840 Use a dummy interface.
841 No packets are ever read or written to a virtual network device.
842 Useful for testing, or when setting up a node that only forwards packets for other nodes.
846 Open a raw socket, and bind it to a pre-existing
847 @var{Interface} (eth0 by default).
848 All packets are read from this interface.
849 Packets received for the local node are written to the raw socket.
850 However, at least on Linux, the operating system does not process IP packets destined for the local host.
853 @item uml (not compiled in by default)
854 Create a UNIX socket with the filename specified by
855 @var{Device}, or @file{@value{localstatedir}/run/@var{netname}.umlsocket}
857 Tinc will wait for a User Mode Linux instance to connect to this socket.
860 @item vde (not compiled in by default)
861 Uses the libvdeplug library to connect to a Virtual Distributed Ethernet switch,
862 using the UNIX socket specified by
863 @var{Device}, or @file{@value{localstatedir}/run/vde.ctl}
867 Also, in case tinc does not seem to correctly interpret packets received from the virtual network device,
868 it can be used to change the way packets are interpreted:
871 @item tun (BSD and Linux)
873 Depending on the platform, this can either be with or without an address family header (see below).
876 @item tunnohead (BSD)
877 Set type to tun without an address family header.
878 Tinc will expect packets read from the virtual network device to start with an IP header.
879 On some platforms IPv6 packets cannot be read from or written to the device in this mode.
882 @item tunifhead (BSD)
883 Set type to tun with an address family header.
884 Tinc will expect packets read from the virtual network device
885 to start with a four byte header containing the address family,
886 followed by an IP header.
887 This mode should support both IPv4 and IPv6 packets.
889 @item tap (BSD and Linux)
891 Tinc will expect packets read from the virtual network device
892 to start with an Ethernet header.
896 @item DirectOnly = <yes|no> (no) [experimental]
897 When this option is enabled, packets that cannot be sent directly to the destination node,
898 but which would have to be forwarded by an intermediate node, are dropped instead.
899 When combined with the IndirectData option,
900 packets for nodes for which we do not have a meta connection with are also dropped.
902 @cindex ECDSAPrivateKeyFile
903 @item ECDSAPrivateKeyFile = <@var{path}> (@file{@value{sysconfdir}/tinc/@var{netname}/ecdsa_key.priv})
904 The file in which the private ECDSA key of this tinc daemon resides.
905 This is only used if ExperimentalProtocol is enabled.
907 @cindex ExperimentalProtocol
908 @item ExperimentalProtocol = <yes|no> (no) [experimental]
909 When this option is enabled, experimental protocol enhancements will be used.
910 Ephemeral ECDH will be used for key exchanges,
911 and ECDSA will be used instead of RSA for authentication.
912 When enabled, an ECDSA key must have been generated before with
913 @samp{tincctl generate-ecdsa-keys}.
914 The experimental protocol may change at any time,
915 and there is no guarantee that tinc will run stable when it is used.
918 @item Forwarding = <off|internal|kernel> (internal) [experimental]
919 This option selects the way indirect packets are forwarded.
923 Incoming packets that are not meant for the local node,
924 but which should be forwarded to another node, are dropped.
927 Incoming packets that are meant for another node are forwarded by tinc internally.
929 This is the default mode, and unless you really know you need another forwarding mode, don't change it.
932 Incoming packets are always sent to the TUN/TAP device, even if the packets are not for the local node.
933 This is less efficient, but allows the kernel to apply its routing and firewall rules on them,
934 and can also help debugging.
937 @cindex GraphDumpFile
938 @item GraphDumpFile = <@var{filename}> [experimental]
939 If this option is present,
940 tinc will dump the current network graph to the file @var{filename}
941 every minute, unless there were no changes to the graph.
942 The file is in a format that can be read by graphviz tools.
943 If @var{filename} starts with a pipe symbol |,
944 then the rest of the filename is interpreted as a shell command
945 that is executed, the graph is then sent to stdin.
948 @item Hostnames = <yes|no> (no)
949 This option selects whether IP addresses (both real and on the VPN)
950 should be resolved. Since DNS lookups are blocking, it might affect
951 tinc's efficiency, even stopping the daemon for a few seconds everytime
952 it does a lookup if your DNS server is not responding.
954 This does not affect resolving hostnames to IP addresses from the
958 @item Interface = <@var{interface}>
959 Defines the name of the interface corresponding to the virtual network device.
960 Depending on the operating system and the type of device this may or may not actually set the name of the interface.
961 Under Windows, this variable is used to select which network interface will be used.
962 If you specified a Device, this variable is almost always already correctly set.
965 @item Mode = <router|switch|hub> (router)
966 This option selects the way packets are routed to other daemons.
972 variables in the host configuration files will be used to form a routing table.
973 Only unicast packets of routable protocols (IPv4 and IPv6) are supported in this mode.
975 This is the default mode, and unless you really know you need another mode, don't change it.
979 In this mode the MAC addresses of the packets on the VPN will be used to
980 dynamically create a routing table just like an Ethernet switch does.
981 Unicast, multicast and broadcast packets of every protocol that runs over Ethernet are supported in this mode
982 at the cost of frequent broadcast ARP requests and routing table updates.
984 This mode is primarily useful if you want to bridge Ethernet segments.
988 This mode is almost the same as the switch mode, but instead
989 every packet will be broadcast to the other daemons
990 while no routing table is managed.
994 @item KeyExpire = <@var{seconds}> (3600)
995 This option controls the time the encryption keys used to encrypt the data
996 are valid. It is common practice to change keys at regular intervals to
997 make it even harder for crackers, even though it is thought to be nearly
998 impossible to crack a single key.
1001 @item MACExpire = <@var{seconds}> (600)
1002 This option controls the amount of time MAC addresses are kept before they are removed.
1003 This only has effect when Mode is set to "switch".
1006 @item Name = <@var{name}> [required]
1007 This is a symbolic name for this connection.
1008 The name should consist only of alfanumeric and underscore characters (a-z, A-Z, 0-9 and _).
1010 @cindex PingInterval
1011 @item PingInterval = <@var{seconds}> (60)
1012 The number of seconds of inactivity that tinc will wait before sending a
1013 probe to the other end.
1016 @item PingTimeout = <@var{seconds}> (5)
1017 The number of seconds to wait for a response to pings or to allow meta
1018 connections to block. If the other end doesn't respond within this time,
1019 the connection is terminated, and the others will be notified of this.
1021 @cindex PriorityInheritance
1022 @item PriorityInheritance = <yes|no> (no) [experimental]
1023 When this option is enabled the value of the TOS field of tunneled IPv4 packets
1024 will be inherited by the UDP packets that are sent out.
1027 @item PrivateKey = <@var{key}> [obsolete]
1028 This is the RSA private key for tinc. However, for safety reasons it is
1029 advised to store private keys of any kind in separate files. This prevents
1030 accidental eavesdropping if you are editting the configuration file.
1032 @cindex PrivateKeyFile
1033 @item PrivateKeyFile = <@var{path}> (@file{@value{sysconfdir}/tinc/@var{netname}/rsa_key.priv})
1034 This is the full path name of the RSA private key file that was
1035 generated by @samp{tincctl generate-keys}. It must be a full path, not a
1038 Note that there must be exactly one of PrivateKey
1040 specified in the configuration file.
1042 @cindex ProcessPriority
1043 @item ProcessPriority = <low|normal|high>
1044 When this option is used the priority of the tincd process will be adjusted.
1045 Increasing the priority may help to reduce latency and packet loss on the VPN.
1047 @cindex ReplayWindow
1048 @item ReplayWindow = <bytes> (16)
1049 This is the size of the replay tracking window for each remote node, in bytes.
1050 The window is a bitfield which tracks 1 packet per bit, so for example
1051 the default setting of 16 will track up to 128 packets in the window. In high
1052 bandwidth scenarios, setting this to a higher value can reduce packet loss from
1053 the interaction of replay tracking with underlying real packet loss and/or
1054 reordering. Setting this to zero will disable replay tracking completely and
1055 pass all traffic, but leaves tinc vulnerable to replay-based attacks on your
1059 @cindex StrictSubnets
1060 @item StrictSubnets <yes|no> (no) [experimental]
1061 When this option is enabled tinc will only use Subnet statements which are
1062 present in the host config files in the local
1063 @file{@value{sysconfdir}/tinc/@var{netname}/hosts/} directory.
1065 @cindex TunnelServer
1066 @item TunnelServer = <yes|no> (no) [experimental]
1067 When this option is enabled tinc will no longer forward information between other tinc daemons,
1068 and will only allow connections with nodes for which host config files are present in the local
1069 @file{@value{sysconfdir}/tinc/@var{netname}/hosts/} directory.
1070 Setting this options also implicitly sets StrictSubnets.
1073 @item UDPRcvBuf = <bytes> (OS default)
1074 Sets the socket receive buffer size for the UDP socket, in bytes.
1075 If unset, the default buffer size will be used by the operating system.
1078 @item UDPSndBuf = <bytes> Pq OS default
1079 Sets the socket send buffer size for the UDP socket, in bytes.
1080 If unset, the default buffer size will be used by the operating system.
1085 @c ==================================================================
1086 @node Host configuration variables
1087 @subsection Host configuration variables
1091 @item Address = <@var{IP address}|@var{hostname}> [<port>] [recommended]
1092 This variable is only required if you want to connect to this host. It
1093 must resolve to the external IP address where the host can be reached,
1094 not the one that is internal to the VPN.
1095 If no port is specified, the default Port is used.
1098 @item Cipher = <@var{cipher}> (blowfish)
1099 The symmetric cipher algorithm used to encrypt UDP packets.
1100 Any cipher supported by OpenSSL is recognized.
1101 Furthermore, specifying "none" will turn off packet encryption.
1102 It is best to use only those ciphers which support CBC mode.
1105 @item ClampMSS = <yes|no> (yes)
1106 This option specifies whether tinc should clamp the maximum segment size (MSS)
1107 of TCP packets to the path MTU. This helps in situations where ICMP
1108 Fragmentation Needed or Packet too Big messages are dropped by firewalls.
1111 @item Compression = <@var{level}> (0)
1112 This option sets the level of compression used for UDP packets.
1113 Possible values are 0 (off), 1 (fast zlib) and any integer up to 9 (best zlib),
1114 10 (fast lzo) and 11 (best lzo).
1117 @item Digest = <@var{digest}> (sha1)
1118 The digest algorithm used to authenticate UDP packets.
1119 Any digest supported by OpenSSL is recognized.
1120 Furthermore, specifying "none" will turn off packet authentication.
1122 @cindex IndirectData
1123 @item IndirectData = <yes|no> (no)
1124 This option specifies whether other tinc daemons besides the one you
1125 specified with ConnectTo can make a direct connection to you. This is
1126 especially useful if you are behind a firewall and it is impossible to
1127 make a connection from the outside to your tinc daemon. Otherwise, it
1128 is best to leave this option out or set it to no.
1131 @item MACLength = <@var{bytes}> (4)
1132 The length of the message authentication code used to authenticate UDP packets.
1133 Can be anything from 0
1134 up to the length of the digest produced by the digest algorithm.
1137 @item PMTU = <@var{mtu}> (1514)
1138 This option controls the initial path MTU to this node.
1140 @cindex PMTUDiscovery
1141 @item PMTUDiscovery = <yes|no> (yes)
1142 When this option is enabled, tinc will try to discover the path MTU to this node.
1143 After the path MTU has been discovered, it will be enforced on the VPN.
1146 @item Port = <@var{port}> (655)
1147 This is the port this tinc daemon listens on.
1148 You can use decimal portnumbers or symbolic names (as listed in @file{/etc/services}).
1151 @item PublicKey = <@var{key}> [obsolete]
1152 This is the RSA public key for this host.
1154 @cindex PublicKeyFile
1155 @item PublicKeyFile = <@var{path}> [obsolete]
1156 This is the full path name of the RSA public key file that was generated
1157 by @samp{tincctl generate-keys}. It must be a full path, not a relative
1161 From version 1.0pre4 on tinc will store the public key directly into the
1162 host configuration file in PEM format, the above two options then are not
1163 necessary. Either the PEM format is used, or exactly
1164 @strong{one of the above two options} must be specified
1165 in each host configuration file, if you want to be able to establish a
1166 connection with that host.
1169 @item Subnet = <@var{address}[/@var{prefixlength}[#@var{weight}]]>
1170 The subnet which this tinc daemon will serve.
1171 Tinc tries to look up which other daemon it should send a packet to by searching the appropiate subnet.
1172 If the packet matches a subnet,
1173 it will be sent to the daemon who has this subnet in his host configuration file.
1174 Multiple subnet lines can be specified for each daemon.
1176 Subnets can either be single MAC, IPv4 or IPv6 addresses,
1177 in which case a subnet consisting of only that single address is assumed,
1178 or they can be a IPv4 or IPv6 network address with a prefixlength.
1179 Shorthand notations are not supported.
1180 For example, IPv4 subnets must be in a form like 192.168.1.0/24,
1181 where 192.168.1.0 is the network address and 24 is the number of bits set in the netmask.
1182 Note that subnets like 192.168.1.1/24 are invalid!
1183 Read a networking HOWTO/FAQ/guide if you don't understand this.
1184 IPv6 subnets are notated like fec0:0:0:1:0:0:0:0/64.
1185 MAC addresses are notated like 0:1a:2b:3c:4d:5e.
1187 @cindex CIDR notation
1188 Prefixlength is the number of bits set to 1 in the netmask part; for
1189 example: netmask 255.255.255.0 would become /24, 255.255.252.0 becomes
1190 /22. This conforms to standard CIDR notation as described in
1191 @uref{ftp://ftp.isi.edu/in-notes/rfc1519.txt, RFC1519}
1193 A Subnet can be given a weight to indicate its priority over identical Subnets
1194 owned by different nodes. The default weight is 10. Lower values indicate
1195 higher priority. Packets will be sent to the node with the highest priority,
1196 unless that node is not reachable, in which case the node with the next highest
1197 priority will be tried, and so on.
1200 @item TCPonly = <yes|no> (no)
1201 If this variable is set to yes, then the packets are tunnelled over a
1202 TCP connection instead of a UDP connection. This is especially useful
1203 for those who want to run a tinc daemon from behind a masquerading
1204 firewall, or if UDP packet routing is disabled somehow.
1205 Setting this options also implicitly sets IndirectData.
1209 @c ==================================================================
1214 Apart from reading the server and host configuration files,
1215 tinc can also run scripts at certain moments.
1216 Under Windows (not Cygwin), the scripts should have the extension .bat.
1220 @item @value{sysconfdir}/tinc/@var{netname}/tinc-up
1221 This is the most important script.
1222 If it is present it will be executed right after the tinc daemon has been
1223 started and has connected to the virtual network device.
1224 It should be used to set up the corresponding network interface,
1225 but can also be used to start other things.
1226 Under Windows you can use the Network Connections control panel instead of creating this script.
1229 @item @value{sysconfdir}/tinc/@var{netname}/tinc-down
1230 This script is started right before the tinc daemon quits.
1232 @item @value{sysconfdir}/tinc/@var{netname}/hosts/@var{host}-up
1233 This script is started when the tinc daemon with name @var{host} becomes reachable.
1235 @item @value{sysconfdir}/tinc/@var{netname}/hosts/@var{host}-down
1236 This script is started when the tinc daemon with name @var{host} becomes unreachable.
1238 @item @value{sysconfdir}/tinc/@var{netname}/host-up
1239 This script is started when any host becomes reachable.
1241 @item @value{sysconfdir}/tinc/@var{netname}/host-down
1242 This script is started when any host becomes unreachable.
1244 @item @value{sysconfdir}/tinc/@var{netname}/subnet-up
1245 This script is started when a Subnet becomes reachable.
1246 The Subnet and the node it belongs to are passed in environment variables.
1248 @item @value{sysconfdir}/tinc/@var{netname}/subnet-down
1249 This script is started when a Subnet becomes unreachable.
1252 @cindex environment variables
1253 The scripts are started without command line arguments,
1254 but can make use of certain environment variables.
1255 Under UNIX like operating systems the names of environment variables must be preceded by a $ in scripts.
1256 Under Windows, in @file{.bat} files, they have to be put between % signs.
1261 If a netname was specified, this environment variable contains it.
1265 Contains the name of this tinc daemon.
1269 Contains the name of the virtual network device that tinc uses.
1273 Contains the name of the virtual network interface that tinc uses.
1274 This should be used for commands like ifconfig.
1278 When a host becomes (un)reachable, this is set to its name.
1279 If a subnet becomes (un)reachable, this is set to the owner of that subnet.
1281 @cindex REMOTEADDRESS
1283 When a host becomes (un)reachable, this is set to its real address.
1287 When a host becomes (un)reachable,
1288 this is set to the port number it uses for communication with other tinc daemons.
1292 When a subnet becomes (un)reachable, this is set to the subnet.
1297 @c ==================================================================
1298 @node How to configure
1299 @subsection How to configure
1301 @subsubheading Step 1. Creating the main configuration file
1303 The main configuration file will be called @file{@value{sysconfdir}/tinc/@var{netname}/tinc.conf}.
1304 Adapt the following example to create a basic configuration file:
1307 Name = @var{yourname}
1308 Device = @file{/dev/tap0}
1311 Then, if you know to which other tinc daemon(s) yours is going to connect,
1312 add `ConnectTo' values.
1314 @subsubheading Step 2. Creating your host configuration file
1316 If you added a line containing `Name = yourname' in the main configuarion file,
1317 you will need to create a host configuration file @file{@value{sysconfdir}/tinc/@var{netname}/hosts/yourname}.
1318 Adapt the following example to create a host configuration file:
1321 Address = your.real.hostname.org
1322 Subnet = 192.168.1.0/24
1325 You can also use an IP address instead of a hostname.
1326 The `Subnet' specifies the address range that is local for @emph{your part of the VPN only}.
1327 If you have multiple address ranges you can specify more than one `Subnet'.
1328 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).
1331 @c ==================================================================
1332 @node Generating keypairs
1333 @section Generating keypairs
1335 @cindex key generation
1336 Now that you have already created the main configuration file and your host configuration file,
1337 you can easily create a public/private keypair by entering the following command:
1340 tincctl -n @var{netname} generate-keys
1343 Tinc will generate a public and a private key and ask you where to put them.
1344 Just press enter to accept the defaults.
1347 @c ==================================================================
1348 @node Network interfaces
1349 @section Network interfaces
1351 Before tinc can start transmitting data over the tunnel, it must
1352 set up the virtual network interface.
1354 First, decide which IP addresses you want to have associated with these
1355 devices, and what network mask they must have.
1357 Tinc will open a virtual network device (@file{/dev/tun}, @file{/dev/tap0} or similar),
1358 which will also create a network interface called something like @samp{tun0}, @samp{tap0}.
1359 If you are using the Linux tun/tap driver, the network interface will by default have the same name as the @var{netname}.
1360 Under Windows you can change the name of the network interface from the Network Connections control panel.
1363 You can configure the network interface by putting ordinary ifconfig, route, and other commands
1364 to a script named @file{@value{sysconfdir}/tinc/@var{netname}/tinc-up}.
1365 When tinc starts, this script will be executed. When tinc exits, it will execute the script named
1366 @file{@value{sysconfdir}/tinc/@var{netname}/tinc-down}, but normally you don't need to create that script.
1368 An example @file{tinc-up} script:
1372 ifconfig $INTERFACE 192.168.1.1 netmask 255.255.0.0
1375 This script gives the interface an IP address and a netmask.
1376 The kernel will also automatically add a route to this interface, so normally you don't need
1377 to add route commands to the @file{tinc-up} script.
1378 The kernel will also bring the interface up after this command.
1380 The netmask is the mask of the @emph{entire} VPN network, not just your
1383 The exact syntax of the ifconfig and route commands differs from platform to platform.
1384 You can look up the commands for setting addresses and adding routes in @ref{Platform specific information},
1385 but it is best to consult the manpages of those utilities on your platform.
1388 @c ==================================================================
1389 @node Example configuration
1390 @section Example configuration
1394 Imagine the following situation. Branch A of our example `company' wants to connect
1395 three branch offices in B, C and D using the Internet. All four offices
1396 have a 24/7 connection to the Internet.
1398 A is going to serve as the center of the network. B and C will connect
1399 to A, and D will connect to C. Each office will be assigned their own IP
1403 A: net 10.1.0.0 mask 255.255.0.0 gateway 10.1.54.1 internet IP 1.2.3.4
1404 B: net 10.2.0.0 mask 255.255.0.0 gateway 10.2.1.12 internet IP 2.3.4.5
1405 C: net 10.3.0.0 mask 255.255.0.0 gateway 10.3.69.254 internet IP 3.4.5.6
1406 D: net 10.4.0.0 mask 255.255.0.0 gateway 10.4.3.32 internet IP 4.5.6.7
1409 Here, ``gateway'' is the VPN IP address of the machine that is running the
1410 tincd, and ``internet IP'' is the IP address of the firewall, which does not
1411 need to run tincd, but it must do a port forwarding of TCP and UDP on port
1412 655 (unless otherwise configured).
1414 In this example, it is assumed that eth0 is the interface that points to
1415 the inner (physical) LAN of the office, although this could also be the
1416 same as the interface that leads to the Internet. The configuration of
1417 the real interface is also shown as a comment, to give you an idea of
1418 how these example host is set up. All branches use the netname `company'
1419 for this particular VPN.
1421 @subsubheading For Branch A
1423 @emph{BranchA} would be configured like this:
1425 In @file{@value{sysconfdir}/tinc/company/tinc-up}:
1428 # Real interface of internal network:
1429 # ifconfig eth0 10.1.54.1 netmask 255.255.0.0
1431 ifconfig $INTERFACE 10.1.54.1 netmask 255.0.0.0
1434 and in @file{@value{sysconfdir}/tinc/company/tinc.conf}:
1441 On all hosts, @file{@value{sysconfdir}/tinc/company/hosts/BranchA} contains:
1444 Subnet = 10.1.0.0/16
1447 -----BEGIN RSA PUBLIC KEY-----
1449 -----END RSA PUBLIC KEY-----
1452 Note that the IP addresses of eth0 and tap0 are the same.
1453 This is quite possible, if you make sure that the netmasks of the interfaces are different.
1454 It is in fact recommended to give both real internal network interfaces and tap interfaces the same IP address,
1455 since that will make things a lot easier to remember and set up.
1458 @subsubheading For Branch B
1460 In @file{@value{sysconfdir}/tinc/company/tinc-up}:
1463 # Real interface of internal network:
1464 # ifconfig eth0 10.2.43.8 netmask 255.255.0.0
1466 ifconfig $INTERFACE 10.2.1.12 netmask 255.0.0.0
1469 and in @file{@value{sysconfdir}/tinc/company/tinc.conf}:
1476 Note here that the internal address (on eth0) doesn't have to be the
1477 same as on the tap0 device. Also, ConnectTo is given so that this node will
1478 always try to connect to BranchA.
1480 On all hosts, in @file{@value{sysconfdir}/tinc/company/hosts/BranchB}:
1483 Subnet = 10.2.0.0/16
1486 -----BEGIN RSA PUBLIC KEY-----
1488 -----END RSA PUBLIC KEY-----
1492 @subsubheading For Branch C
1494 In @file{@value{sysconfdir}/tinc/company/tinc-up}:
1497 # Real interface of internal network:
1498 # ifconfig eth0 10.3.69.254 netmask 255.255.0.0
1500 ifconfig $INTERFACE 10.3.69.254 netmask 255.0.0.0
1503 and in @file{@value{sysconfdir}/tinc/company/tinc.conf}:
1511 C already has another daemon that runs on port 655, so they have to
1512 reserve another port for tinc. It knows the portnumber it has to listen on
1513 from it's own host configuration file.
1515 On all hosts, in @file{@value{sysconfdir}/tinc/company/hosts/BranchC}:
1519 Subnet = 10.3.0.0/16
1522 -----BEGIN RSA PUBLIC KEY-----
1524 -----END RSA PUBLIC KEY-----
1528 @subsubheading For Branch D
1530 In @file{@value{sysconfdir}/tinc/company/tinc-up}:
1533 # Real interface of internal network:
1534 # ifconfig eth0 10.4.3.32 netmask 255.255.0.0
1536 ifconfig $INTERFACE 10.4.3.32 netmask 255.0.0.0
1539 and in @file{@value{sysconfdir}/tinc/company/tinc.conf}:
1544 Device = /dev/net/tun
1547 D will be connecting to C, which has a tincd running for this network on
1548 port 2000. It knows the port number from the host configuration file.
1549 Also note that since D uses the tun/tap driver, the network interface
1550 will not be called `tun' or `tap0' or something like that, but will
1551 have the same name as netname.
1553 On all hosts, in @file{@value{sysconfdir}/tinc/company/hosts/BranchD}:
1556 Subnet = 10.4.0.0/16
1559 -----BEGIN RSA PUBLIC KEY-----
1561 -----END RSA PUBLIC KEY-----
1564 @subsubheading Key files
1566 A, B, C and D all have generated a public/private keypair with the following command:
1569 tincctl -n company generate-keys
1572 The private key is stored in @file{@value{sysconfdir}/tinc/company/rsa_key.priv},
1573 the public key is put into the host configuration file in the @file{@value{sysconfdir}/tinc/company/hosts/} directory.
1574 During key generation, tinc automatically guesses the right filenames based on the -n option and
1575 the Name directive in the @file{tinc.conf} file (if it is available).
1577 @subsubheading Starting
1579 After each branch has finished configuration and they have distributed
1580 the host configuration files amongst them, they can start their tinc daemons.
1581 They don't necessarily have to wait for the other branches to have started
1582 their daemons, tinc will try connecting until they are available.
1585 @c ==================================================================
1587 @chapter Running tinc
1589 If everything else is done, you can start tinc by typing the following command:
1592 tincd -n @var{netname}
1596 Tinc will detach from the terminal and continue to run in the background like a good daemon.
1597 If there are any problems however you can try to increase the debug level
1598 and look in the syslog to find out what the problems are.
1604 * Solving problems::
1606 * Sending bug reports::
1610 @c ==================================================================
1611 @node Runtime options
1612 @section Runtime options
1614 Besides the settings in the configuration file, tinc also accepts some
1615 command line options.
1617 @cindex command line
1618 @cindex runtime options
1622 @item -c, --config=@var{path}
1623 Read configuration options from the directory @var{path}. The default is
1624 @file{@value{sysconfdir}/tinc/@var{netname}/}.
1626 @item -D, --no-detach
1627 Don't fork and detach.
1628 This will also disable the automatic restart mechanism for fatal errors.
1631 @item -d, --debug=@var{level}
1632 Set debug level to @var{level}. The higher the debug level, the more gets
1633 logged. Everything goes via syslog.
1635 @item -n, --net=@var{netname}
1636 Use configuration for net @var{netname}.
1637 This will let tinc read all configuration files from
1638 @file{@value{sysconfdir}/tinc/@var{netname}/}.
1639 Specifying . for @var{netname} is the same as not specifying any @var{netname}.
1640 @xref{Multiple networks}.
1642 @item --pidfile=@var{filename}
1643 Store a cookie in @var{filename} which allows tincctl to authenticate.
1644 If unspecified, the default is
1645 @file{@value{localstatedir}/run/tinc.@var{netname}.pid}.
1647 @item -o, --option=[@var{HOST}.]@var{KEY}=@var{VALUE}
1648 Without specifying a @var{HOST}, this will set server configuration variable @var{KEY} to @var{VALUE}.
1649 If specified as @var{HOST}.@var{KEY}=@var{VALUE},
1650 this will set the host configuration variable @var{KEY} of the host named @var{HOST} to @var{VALUE}.
1651 This option can be used more than once to specify multiple configuration variables.
1654 Lock tinc into main memory.
1655 This will prevent sensitive data like shared private keys to be written to the system swap files/partitions.
1657 @item --logfile[=@var{file}]
1658 Write log entries to a file instead of to the system logging facility.
1659 If @var{file} is omitted, the default is @file{@value{localstatedir}/log/tinc.@var{netname}.log}.
1661 @item --bypass-security
1662 Disables encryption and authentication.
1663 Only useful for debugging.
1666 Change process root directory to the directory where the config file is
1667 located (@file{@value{sysconfdir}/tinc/@var{netname}/} as determined by
1668 -n/--net option or as given by -c/--config option), for added security.
1669 The chroot is performed after all the initialization is done, after
1670 writing pid files and opening network sockets.
1672 Note that this option alone does not do any good without -U/--user, below.
1674 Note also that tinc can't run scripts anymore (such as tinc-down or host-up),
1675 unless it's setup to be runnable inside chroot environment.
1677 @item -U, --user=@var{user}
1678 Switch to the given @var{user} after initialization, at the same time as
1679 chroot is performed (see --chroot above). With this option tinc drops
1680 privileges, for added security.
1683 Display a short reminder of these runtime options and terminate.
1686 Output version information and exit.
1690 @c ==================================================================
1695 You can also send the following signals to a running tincd process:
1701 Forces tinc to try to connect to all uplinks immediately.
1702 Usually tinc attempts to do this itself,
1703 but increases the time it waits between the attempts each time it failed,
1704 and if tinc didn't succeed to connect to an uplink the first time after it started,
1705 it defaults to the maximum time of 15 minutes.
1708 Partially rereads configuration files.
1709 Connections to hosts whose host config file are removed are closed.
1710 New outgoing connections specified in @file{tinc.conf} will be made.
1711 If the --logfile option is used, this will also close and reopen the log file,
1712 useful when log rotation is used.
1716 @c ==================================================================
1718 @section Debug levels
1720 @cindex debug levels
1721 The tinc daemon can send a lot of messages to the syslog.
1722 The higher the debug level, the more messages it will log.
1723 Each level inherits all messages of the previous level:
1729 This will log a message indicating tinc has started along with a version number.
1730 It will also log any serious error.
1733 This will log all connections that are made with other tinc daemons.
1736 This will log status and error messages from scripts and other tinc daemons.
1739 This will log all requests that are exchanged with other tinc daemons. These include
1740 authentication, key exchange and connection list updates.
1743 This will log a copy of everything received on the meta socket.
1746 This will log all network traffic over the virtual private network.
1750 @c ==================================================================
1751 @node Solving problems
1752 @section Solving problems
1754 If tinc starts without problems, but if the VPN doesn't work, you will have to find the cause of the problem.
1755 The first thing to do is to start tinc with a high debug level in the foreground,
1756 so you can directly see everything tinc logs:
1759 tincd -n @var{netname} -d5 -D
1762 If tinc does not log any error messages, then you might want to check the following things:
1765 @item @file{tinc-up} script
1766 Does this script contain the right commands?
1767 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.
1770 Does the Subnet (or Subnets) in the host configuration file of this host match the portion of the VPN that belongs to this host?
1772 @item Firewalls and NATs
1773 Do you have a firewall or a NAT device (a masquerading firewall or perhaps an ADSL router that performs masquerading)?
1774 If so, check that it allows TCP and UDP traffic on port 655.
1775 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.
1776 You can add @samp{TCPOnly = yes} to your host config file to force tinc to only use a single TCP connection,
1777 this works through most firewalls and NATs.
1782 @c ==================================================================
1783 @node Error messages
1784 @section Error messages
1786 What follows is a list of the most common error messages you might find in the logs.
1787 Some of them will only be visible if the debug level is high enough.
1790 @item Could not open /dev/tap0: No such device
1793 @item You forgot to `modprobe netlink_dev' or `modprobe ethertap'.
1794 @item You forgot to compile `Netlink device emulation' in the kernel.
1797 @item Can't write to /dev/net/tun: No such device
1800 @item You forgot to `modprobe tun'.
1801 @item You forgot to compile `Universal TUN/TAP driver' in the kernel.
1802 @item The tun device is located somewhere else in @file{/dev/}.
1805 @item Network address and prefix length do not match!
1808 @item The Subnet field must contain a @emph{network} address, trailing bits should be 0.
1809 @item If you only want to use one IP address, set the netmask to /32.
1812 @item Error reading RSA key file `rsa_key.priv': No such file or directory
1815 @item You forgot to create a public/private keypair.
1816 @item Specify the complete pathname to the private key file with the @samp{PrivateKeyFile} option.
1819 @item Warning: insecure file permissions for RSA private key file `rsa_key.priv'!
1822 @item The private key file is readable by users other than root.
1823 Use chmod to correct the file permissions.
1826 @item Creating metasocket failed: Address family not supported
1829 @item By default tinc tries to create both IPv4 and IPv6 sockets.
1830 On some platforms this might not be implemented.
1831 If the logs show @samp{Ready} later on, then at least one metasocket was created,
1832 and you can ignore this message.
1833 You can add @samp{AddressFamily = ipv4} to @file{tinc.conf} to prevent this from happening.
1836 @item Cannot route packet: unknown IPv4 destination 1.2.3.4
1839 @item You try to send traffic to a host on the VPN for which no Subnet is known.
1840 @item If it is a broadcast address (ending in .255), it probably is a samba server or a Windows host sending broadcast packets.
1844 @item Cannot route packet: ARP request for unknown address 1.2.3.4
1847 @item You try to send traffic to a host on the VPN for which no Subnet is known.
1850 @item Packet with destination 1.2.3.4 is looping back to us!
1853 @item Something is not configured right. Packets are being sent out to the
1854 virtual network device, but according to the Subnet directives in your host configuration
1855 file, those packets should go to your own host. Most common mistake is that
1856 you have a Subnet line in your host configuration file with a prefix length which is
1857 just as large as the prefix of the virtual network interface. The latter should in almost all
1858 cases be larger. Rethink your configuration.
1859 Note that you will only see this message if you specified a debug
1860 level of 5 or higher!
1861 @item Chances are that a @samp{Subnet = ...} line in the host configuration file of this tinc daemon is wrong.
1862 Change it to a subnet that is accepted locally by another interface,
1863 or if that is not the case, try changing the prefix length into /32.
1866 @item Node foo (1.2.3.4) is not reachable
1869 @item Node foo does not have a connection anymore, its tinc daemon is not running or its connection to the Internet is broken.
1872 @item Received UDP packet from unknown source 1.2.3.4 (port 12345)
1875 @item If you see this only sporadically, it is harmless and caused by a node sending packets using an old key.
1876 @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.
1877 You can add @samp{TCPOnly = yes} to host configuration files to force all VPN traffic to go over a TCP connection.
1880 @item Got bad/bogus/unauthorized REQUEST from foo (1.2.3.4 port 12345)
1883 @item Node foo does not have the right public/private keypair.
1884 Generate new keypairs and distribute them again.
1885 @item An attacker tries to gain access to your VPN.
1886 @item A network error caused corruption of metadata sent from foo.
1891 @c ==================================================================
1892 @node Sending bug reports
1893 @section Sending bug reports
1895 If you really can't find the cause of a problem, or if you suspect tinc is not working right,
1896 you can send us a bugreport, see @ref{Contact information}.
1897 Be sure to include the following information in your bugreport:
1900 @item A clear description of what you are trying to achieve and what the problem is.
1901 @item What platform (operating system, version, hardware architecture) and which version of tinc you use.
1902 @item If compiling tinc fails, a copy of @file{config.log} and the error messages you get.
1903 @item Otherwise, a copy of @file{tinc.conf}, @file{tinc-up} and all files in the @file{hosts/} directory.
1904 @item The output of the commands @samp{ifconfig -a} and @samp{route -n} (or @samp{netstat -rn} if that doesn't work).
1905 @item The output of any command that fails to work as it should (like ping or traceroute).
1908 @c ==================================================================
1909 @node Controlling tinc
1910 @chapter Controlling tinc
1912 You can control and inspect a running tincd through the tincctl
1913 command. A quick example:
1916 tincctl -n @var{netname} reload
1920 * tincctl runtime options::
1921 * tincctl commands::
1922 * tincctl examples::
1927 @c ==================================================================
1928 @node tincctl runtime options
1929 @section tincctl runtime options
1933 @item -c, --config=@var{path}
1934 Read configuration options from the directory @var{path}. The default is
1935 @file{@value{sysconfdir}/tinc/@var{netname}/}.
1937 @item -n, --net=@var{netname}
1938 Use configuration for net @var{netname}. @xref{Multiple networks}.
1940 @item --pidfile=@var{filename}
1941 Use the cookie from @var{filename} to authenticate with a running tinc daemon.
1942 If unspecified, the default is
1943 @file{@value{localstatedir}/run/tinc.@var{netname}.pid}.
1946 Display a short reminder of runtime options and commands, then terminate.
1949 Output version information and exit.
1954 @c ==================================================================
1955 @node tincctl commands
1956 @section tincctl commands
1968 Restart @samp{tincd}.
1971 Partially rereads configuration files. Connections to hosts whose host
1972 config files are removed are closed. New outgoing connections specified
1973 in @file{tinc.conf} will be made.
1976 Shows the PID of the currently running @samp{tincd}.
1978 @item generate-keys [@var{bits}]
1979 Generate public/private keypair of @var{bits} length. If @var{bits} is not specified,
1980 1024 is the default. tinc will ask where you want to store the files,
1981 but will default to the configuration directory (you can use the -c or -n
1985 Dump a list of all known nodes in the VPN.
1988 Dump a list of all known connections in the VPN.
1991 Dump a list of all known subnets in the VPN.
1993 @item dump connections
1994 Dump a list of all meta connections with ourself.
1997 Dump a graph of the VPN in dotty format.
2000 Purges all information remembered about unreachable nodes.
2002 @item debug @var{level}
2003 Sets debug level to @var{level}.
2006 Forces tinc to try to connect to all uplinks immediately.
2007 Usually tinc attempts to do this itself,
2008 but increases the time it waits between the attempts each time it failed,
2009 and if tinc didn't succeed to connect to an uplink the first time after it started,
2010 it defaults to the maximum time of 15 minutes.
2012 @item disconnect @var{node}
2013 Closes the meta connection with the given @var{node}.
2016 If tincctl is compiled with libcurses support, this will display live traffic statistics for all the known nodes,
2017 similar to the UNIX top command.
2018 See below for more information.
2021 Dump VPN traffic going through the local tinc node in pcap-savefile format to standard output,
2022 from where it can be redirected to a file or piped through a program that can parse it directly,
2027 @c ==================================================================
2028 @node tincctl examples
2029 @section tincctl examples
2031 Examples of some commands:
2034 tincctl -n vpn dump graph | circo -Txlib
2035 tincctl -n vpn pcap | tcpdump -r -
2039 @c ==================================================================
2041 @section tincctl top
2043 The top command connects to a running tinc daemon and repeatedly queries its per-node traffic counters.
2044 It displays a list of all the known nodes in the left-most column,
2045 and the amount of bytes and packets read from and sent to each node in the other columns.
2046 By default, the information is updated every second.
2047 The behaviour of the top command can be changed using the following keys:
2052 Change the interval between updates.
2053 After pressing the @key{s} key, enter the desired interval in seconds, followed by enter.
2054 Fractional seconds are honored.
2055 Intervals lower than 0.1 seconds are not allowed.
2058 Toggle between displaying current traffic rates (in packets and bytes per second)
2059 and cummulative traffic (total packets and bytes since the tinc daemon started).
2062 Sort the list of nodes by name.
2065 Sort the list of nodes by incoming amount of bytes.
2068 Sort the list of nodes by incoming amount of packets.
2071 Sort the list of nodes by outgoing amount of bytes.
2074 Sort the list of nodes by outgoing amount of packets.
2077 Sort the list of nodes by sum of incoming and outgoing amount of bytes.
2080 Sort the list of nodes by sum of incoming and outgoing amount of packets.
2083 Show amount of traffic in bytes.
2086 Show amount of traffic in kilobytes.
2089 Show amount of traffic in megabytes.
2092 Show amount of traffic in gigabytes.
2100 @c ==================================================================
2101 @node Technical information
2102 @chapter Technical information
2107 * The meta-protocol::
2112 @c ==================================================================
2113 @node The connection
2114 @section The connection
2117 Tinc is a daemon that takes VPN data and transmit that to another host
2118 computer over the existing Internet infrastructure.
2122 * The meta-connection::
2126 @c ==================================================================
2127 @node The UDP tunnel
2128 @subsection The UDP tunnel
2130 @cindex virtual network device
2132 The data itself is read from a character device file, the so-called
2133 @emph{virtual network device}. This device is associated with a network
2134 interface. Any data sent to this interface can be read from the device,
2135 and any data written to the device gets sent from the interface.
2136 There are two possible types of virtual network devices:
2137 `tun' style, which are point-to-point devices which can only handle IPv4 and/or IPv6 packets,
2138 and `tap' style, which are Ethernet devices and handle complete Ethernet frames.
2140 So when tinc reads an Ethernet frame from the device, it determines its
2141 type. When tinc is in it's default routing mode, it can handle IPv4 and IPv6
2142 packets. Depending on the Subnet lines, it will send the packets off to their destination IP address.
2143 In the `switch' and `hub' mode, tinc will use broadcasts and MAC address discovery
2144 to deduce the destination of the packets.
2145 Since the latter modes only depend on the link layer information,
2146 any protocol that runs over Ethernet is supported (for instance IPX and Appletalk).
2147 However, only `tap' style devices provide this information.
2149 After the destination has been determined,
2150 the packet will be compressed (optionally),
2151 a sequence number will be added to the packet,
2152 the packet will then be encrypted
2153 and a message authentication code will be appended.
2155 @cindex encapsulating
2157 When that is done, time has come to actually transport the
2158 packet to the destination computer. We do this by sending the packet
2159 over an UDP connection to the destination host. This is called
2160 @emph{encapsulating}, the VPN packet (though now encrypted) is
2161 encapsulated in another IP datagram.
2163 When the destination receives this packet, the same thing happens, only
2164 in reverse. So it checks the message authentication code, decrypts the contents of the UDP datagram,
2165 checks the sequence number
2166 and writes the decrypted information to its own virtual network device.
2168 If the virtual network device is a `tun' device (a point-to-point tunnel),
2169 there is no problem for the kernel to accept a packet.
2170 However, if it is a `tap' device (this is the only available type on FreeBSD),
2171 the destination MAC address must match that of the virtual network interface.
2172 If tinc is in it's default routing mode, ARP does not work, so the correct destination MAC
2173 can not be known by the sending host.
2174 Tinc solves this by letting the receiving end detect the MAC address of its own virtual network interface
2175 and overwriting the destination MAC address of the received packet.
2177 In switch or hub modes ARP does work so the sender already knows the correct destination MAC address.
2178 In those modes every interface should have a unique MAC address, so make sure they are not the same.
2179 Because switch and hub modes rely on MAC addresses to function correctly,
2180 these modes cannot be used on the following operating systems which don't have a `tap' style virtual network device:
2181 OpenBSD, NetBSD, Darwin and Solaris.
2184 @c ==================================================================
2185 @node The meta-connection
2186 @subsection The meta-connection
2188 Having only a UDP connection available is not enough. Though suitable
2189 for transmitting data, we want to be able to reliably send other
2190 information, such as routing and session key information to somebody.
2193 TCP is a better alternative, because it already contains protection
2194 against information being lost, unlike UDP.
2196 So we establish two connections. One for the encrypted VPN data, and one
2197 for other information, the meta-data. Hence, we call the second
2198 connection the meta-connection. We can now be sure that the
2199 meta-information doesn't get lost on the way to another computer.
2201 @cindex data-protocol
2202 @cindex meta-protocol
2203 Like with any communication, we must have a protocol, so that everybody
2204 knows what everything stands for, and how she should react. Because we
2205 have two connections, we also have two protocols. The protocol used for
2206 the UDP data is the ``data-protocol,'' the other one is the
2209 The reason we don't use TCP for both protocols is that UDP is much
2210 better for encapsulation, even while it is less reliable. The real
2211 problem is that when TCP would be used to encapsulate a TCP stream
2212 that's on the private network, for every packet sent there would be
2213 three ACKs sent instead of just one. Furthermore, if there would be
2214 a timeout, both TCP streams would sense the timeout, and both would
2215 start re-sending packets.
2218 @c ==================================================================
2219 @node The meta-protocol
2220 @section The meta-protocol
2222 The meta protocol is used to tie all tinc daemons together, and
2223 exchange information about which tinc daemon serves which virtual
2226 The meta protocol consists of requests that can be sent to the other
2227 side. Each request has a unique number and several parameters. All
2228 requests are represented in the standard ASCII character set. It is
2229 possible to use tools such as telnet or netcat to connect to a tinc
2230 daemon started with the --bypass-security option
2231 and to read and write requests by hand, provided that one
2232 understands the numeric codes sent.
2234 The authentication scheme is described in @ref{Authentication protocol}. After a
2235 successful authentication, the server and the client will exchange all the
2236 information about other tinc daemons and subnets they know of, so that both
2237 sides (and all the other tinc daemons behind them) have their information
2244 ------------------------------------------------------------------
2245 ADD_EDGE node1 node2 21.32.43.54 655 222 0
2246 | | | | | +-> options
2247 | | | | +----> weight
2248 | | | +--------> UDP port of node2
2249 | | +----------------> real address of node2
2250 | +-------------------------> name of destination node
2251 +-------------------------------> name of source node
2253 ADD_SUBNET node 192.168.1.0/24
2254 | | +--> prefixlength
2255 | +--------> network address
2256 +------------------> owner of this subnet
2257 ------------------------------------------------------------------
2260 The ADD_EDGE messages are to inform other tinc daemons that a connection between
2261 two nodes exist. The address of the destination node is available so that
2262 VPN packets can be sent directly to that node.
2264 The ADD_SUBNET messages inform other tinc daemons that certain subnets belong
2265 to certain nodes. tinc will use it to determine to which node a VPN packet has
2272 ------------------------------------------------------------------
2273 DEL_EDGE node1 node2
2274 | +----> name of destination node
2275 +----------> name of source node
2277 DEL_SUBNET node 192.168.1.0/24
2278 | | +--> prefixlength
2279 | +--------> network address
2280 +------------------> owner of this subnet
2281 ------------------------------------------------------------------
2284 In case a connection between two daemons is closed or broken, DEL_EDGE messages
2285 are sent to inform the other daemons of that fact. Each daemon will calculate a
2286 new route to the the daemons, or mark them unreachable if there isn't any.
2293 ------------------------------------------------------------------
2294 REQ_KEY origin destination
2295 | +--> name of the tinc daemon it wants the key from
2296 +----------> name of the daemon that wants the key
2298 ANS_KEY origin destination 4ae0b0a82d6e0078 91 64 4
2299 | | \______________/ | | +--> MAC length
2300 | | | | +-----> digest algorithm
2301 | | | +--------> cipher algorithm
2302 | | +--> 128 bits key
2303 | +--> name of the daemon that wants the key
2304 +----------> name of the daemon that uses this key
2307 +--> daemon that has changed it's packet key
2308 ------------------------------------------------------------------
2311 The keys used to encrypt VPN packets are not sent out directly. This is
2312 because it would generate a lot of traffic on VPNs with many daemons, and
2313 chances are that not every tinc daemon will ever send a packet to every
2314 other daemon. Instead, if a daemon needs a key it sends a request for it
2315 via the meta connection of the nearest hop in the direction of the
2322 ------------------------------------------------------------------
2325 ------------------------------------------------------------------
2328 There is also a mechanism to check if hosts are still alive. Since network
2329 failures or a crash can cause a daemon to be killed without properly
2330 shutting down the TCP connection, this is necessary to keep an up to date
2331 connection list. PINGs are sent at regular intervals, except when there
2332 is also some other traffic. A little bit of salt (random data) is added
2333 with each PING and PONG message, to make sure that long sequences of PING/PONG
2334 messages without any other traffic won't result in known plaintext.
2336 This basically covers what is sent over the meta connection by tinc.
2339 @c ==================================================================
2345 Tinc got its name from ``TINC,'' short for @emph{There Is No Cabal}; the
2346 alleged Cabal was/is an organisation that was said to keep an eye on the
2347 entire Internet. As this is exactly what you @emph{don't} want, we named
2348 the tinc project after TINC.
2351 But in order to be ``immune'' to eavesdropping, you'll have to encrypt
2352 your data. Because tinc is a @emph{Secure} VPN (SVPN) daemon, it does
2353 exactly that: encrypt.
2354 Tinc by default uses blowfish encryption with 128 bit keys in CBC mode, 32 bit
2355 sequence numbers and 4 byte long message authentication codes to make sure
2356 eavesdroppers cannot get and cannot change any information at all from the
2357 packets they can intercept. The encryption algorithm and message authentication
2358 algorithm can be changed in the configuration. The length of the message
2359 authentication codes is also adjustable. The length of the key for the
2360 encryption algorithm is always the default length used by OpenSSL.
2363 * Authentication protocol::
2364 * Encryption of network packets::
2369 @c ==================================================================
2370 @node Authentication protocol
2371 @subsection Authentication protocol
2373 @cindex authentication
2374 A new scheme for authentication in tinc has been devised, which offers some
2375 improvements over the protocol used in 1.0pre2 and 1.0pre3. Explanation is
2385 --------------------------------------------------------------------------
2386 client <attempts connection>
2388 server <accepts connection>
2392 +-------> name of tinc daemon
2396 +-------> name of tinc daemon
2398 client META_KEY 5f0823a93e35b69e...7086ec7866ce582b
2399 \_________________________________/
2400 +-> RSAKEYLEN bits totally random string S1,
2401 encrypted with server's public RSA key
2403 server META_KEY 6ab9c1640388f8f0...45d1a07f8a672630
2404 \_________________________________/
2405 +-> RSAKEYLEN bits totally random string S2,
2406 encrypted with client's public RSA key
2409 - the client will symmetrically encrypt outgoing traffic using S1
2410 - the server will symmetrically encrypt outgoing traffic using S2
2412 client CHALLENGE da02add1817c1920989ba6ae2a49cecbda0
2413 \_________________________________/
2414 +-> CHALLEN bits totally random string H1
2416 server CHALLENGE 57fb4b2ccd70d6bb35a64c142f47e61d57f
2417 \_________________________________/
2418 +-> CHALLEN bits totally random string H2
2420 client CHAL_REPLY 816a86
2421 +-> 160 bits SHA1 of H2
2423 server CHAL_REPLY 928ffe
2424 +-> 160 bits SHA1 of H1
2426 After the correct challenge replies are received, both ends have proved
2427 their identity. Further information is exchanged.
2429 client ACK 655 123 0
2431 | +----> estimated weight
2432 +--------> listening port of client
2434 server ACK 655 321 0
2436 | +----> estimated weight
2437 +--------> listening port of server
2438 --------------------------------------------------------------------------
2441 This new scheme has several improvements, both in efficiency and security.
2443 First of all, the server sends exactly the same kind of messages over the wire
2444 as the client. The previous versions of tinc first authenticated the client,
2445 and then the server. This scheme even allows both sides to send their messages
2446 simultaneously, there is no need to wait for the other to send something first.
2447 This means that any calculations that need to be done upon sending or receiving
2448 a message can also be done in parallel. This is especially important when doing
2449 RSA encryption/decryption. Given that these calculations are the main part of
2450 the CPU time spent for the authentication, speed is improved by a factor 2.
2452 Second, only one RSA encrypted message is sent instead of two. This reduces the
2453 amount of information attackers can see (and thus use for a cryptographic
2454 attack). It also improves speed by a factor two, making the total speedup a
2457 Third, and most important:
2458 The symmetric cipher keys are exchanged first, the challenge is done
2459 afterwards. In the previous authentication scheme, because a man-in-the-middle
2460 could pass the challenge/chal_reply phase (by just copying the messages between
2461 the two real tinc daemons), but no information was exchanged that was really
2462 needed to read the rest of the messages, the challenge/chal_reply phase was of
2463 no real use. The man-in-the-middle was only stopped by the fact that only after
2464 the ACK messages were encrypted with the symmetric cipher. Potentially, it
2465 could even send it's own symmetric key to the server (if it knew the server's
2466 public key) and read some of the metadata the server would send it (it was
2467 impossible for the mitm to read actual network packets though). The new scheme
2468 however prevents this.
2470 This new scheme makes sure that first of all, symmetric keys are exchanged. The
2471 rest of the messages are then encrypted with the symmetric cipher. Then, each
2472 side can only read received messages if they have their private key. The
2473 challenge is there to let the other side know that the private key is really
2474 known, because a challenge reply can only be sent back if the challenge is
2475 decrypted correctly, and that can only be done with knowledge of the private
2478 Fourth: the first thing that is sent via the symmetric cipher encrypted
2479 connection is a totally random string, so that there is no known plaintext (for
2480 an attacker) in the beginning of the encrypted stream.
2483 @c ==================================================================
2484 @node Encryption of network packets
2485 @subsection Encryption of network packets
2488 A data packet can only be sent if the encryption key is known to both
2489 parties, and the connection is activated. If the encryption key is not
2490 known, a request is sent to the destination using the meta connection
2491 to retrieve it. The packet is stored in a queue while waiting for the
2495 The UDP packet containing the network packet from the VPN has the following layout:
2498 ... | IP header | UDP header | seqno | VPN packet | MAC | UDP trailer
2499 \___________________/\_____/
2501 V +---> digest algorithm
2502 Encrypted with symmetric cipher
2505 So, the entire VPN packet is encrypted using a symmetric cipher, including a 32 bits
2506 sequence number that is added in front of the actual VPN packet, to act as a unique
2507 IV for each packet and to prevent replay attacks. A message authentication code
2508 is added to the UDP packet to prevent alteration of packets. By default the
2509 first 4 bytes of the digest are used for this, but this can be changed using
2510 the MACLength configuration variable.
2512 @c ==================================================================
2513 @node Security issues
2514 @subsection Security issues
2516 In August 2000, we discovered the existence of a security hole in all versions
2517 of tinc up to and including 1.0pre2. This had to do with the way we exchanged
2518 keys. Since then, we have been working on a new authentication scheme to make
2519 tinc as secure as possible. The current version uses the OpenSSL library and
2520 uses strong authentication with RSA keys.
2522 On the 29th of December 2001, Jerome Etienne posted a security analysis of tinc
2523 1.0pre4. Due to a lack of sequence numbers and a message authentication code
2524 for each packet, an attacker could possibly disrupt certain network services or
2525 launch a denial of service attack by replaying intercepted packets. The current
2526 version adds sequence numbers and message authentication codes to prevent such
2529 On the 15th of September 2003, Peter Gutmann posted a security analysis of tinc
2530 1.0.1. He argues that the 32 bit sequence number used by tinc is not a good IV,
2531 that tinc's default length of 4 bytes for the MAC is too short, and he doesn't
2532 like tinc's use of RSA during authentication. We do not know of a security hole
2533 in this version of tinc, but tinc's security is not as strong as TLS or IPsec.
2534 We will address these issues in tinc 2.0.
2536 Cryptography is a hard thing to get right. We cannot make any
2537 guarantees. Time, review and feedback are the only things that can
2538 prove the security of any cryptographic product. If you wish to review
2539 tinc or give us feedback, you are stronly encouraged to do so.
2542 @c ==================================================================
2543 @node Platform specific information
2544 @chapter Platform specific information
2547 * Interface configuration::
2551 @c ==================================================================
2552 @node Interface configuration
2553 @section Interface configuration
2555 When configuring an interface, one normally assigns it an address and a
2556 netmask. The address uniquely identifies the host on the network attached to
2557 the interface. The netmask, combined with the address, forms a subnet. It is
2558 used to add a route to the routing table instructing the kernel to send all
2559 packets which fall into that subnet to that interface. Because all packets for
2560 the entire VPN should go to the virtual network interface used by tinc, the
2561 netmask should be such that it encompasses the entire VPN.
2565 @multitable {Darwin (MacOS/X)} {ifconfig route add -bla network address netmask netmask prefixlength interface}
2567 @tab @code{ifconfig} @var{interface} @var{address} @code{netmask} @var{netmask}
2568 @item Linux iproute2
2569 @tab @code{ip addr add} @var{address}@code{/}@var{prefixlength} @code{dev} @var{interface}
2571 @tab @code{ifconfig} @var{interface} @var{address} @code{netmask} @var{netmask}
2573 @tab @code{ifconfig} @var{interface} @var{address} @code{netmask} @var{netmask}
2575 @tab @code{ifconfig} @var{interface} @var{address} @code{netmask} @var{netmask}
2577 @tab @code{ifconfig} @var{interface} @var{address} @code{netmask} @var{netmask}
2578 @item Darwin (MacOS/X)
2579 @tab @code{ifconfig} @var{interface} @var{address} @code{netmask} @var{netmask}
2581 @tab @code{netsh interface ip set address} @var{interface} @code{static} @var{address} @var{netmask}
2587 @multitable {Darwin (MacOS/X)} {ifconfig route add -bla network address netmask netmask prefixlength interface}
2589 @tab @code{ifconfig} @var{interface} @code{add} @var{address}@code{/}@var{prefixlength}
2591 @tab @code{ifconfig} @var{interface} @code{inet6} @var{address} @code{prefixlen} @var{prefixlength}
2593 @tab @code{ifconfig} @var{interface} @code{inet6} @var{address} @code{prefixlen} @var{prefixlength}
2595 @tab @code{ifconfig} @var{interface} @code{inet6} @var{address} @code{prefixlen} @var{prefixlength}
2597 @tab @code{ifconfig} @var{interface} @code{inet6 plumb up}
2599 @tab @code{ifconfig} @var{interface} @code{inet6 addif} @var{address} @var{address}
2600 @item Darwin (MacOS/X)
2601 @tab @code{ifconfig} @var{interface} @code{inet6} @var{address} @code{prefixlen} @var{prefixlength}
2603 @tab @code{netsh interface ipv6 add address} @var{interface} @code{static} @var{address}/@var{prefixlength}
2607 @c ==================================================================
2611 In some cases it might be necessary to add more routes to the virtual network
2612 interface. There are two ways to indicate which interface a packet should go
2613 to, one is to use the name of the interface itself, another way is to specify
2614 the (local) address that is assigned to that interface (@var{local_address}). The
2615 former way is unambiguous and therefore preferable, but not all platforms
2618 Adding routes to IPv4 subnets:
2620 @multitable {Darwin (MacOS/X)} {ifconfig route add -bla network address netmask netmask prefixlength interface}
2622 @tab @code{route add -net} @var{network_address} @code{netmask} @var{netmask} @var{interface}
2623 @item Linux iproute2
2624 @tab @code{ip route add} @var{network_address}@code{/}@var{prefixlength} @code{dev} @var{interface}
2626 @tab @code{route add} @var{network_address}@code{/}@var{prefixlength} @var{local_address}
2628 @tab @code{route add} @var{network_address}@code{/}@var{prefixlength} @var{local_address}
2630 @tab @code{route add} @var{network_address}@code{/}@var{prefixlength} @var{local_address}
2632 @tab @code{route add} @var{network_address}@code{/}@var{prefixlength} @var{local_address} @code{-interface}
2633 @item Darwin (MacOS/X)
2634 @tab @code{route add} @var{network_address}@code{/}@var{prefixlength} @var{local_address}
2636 @tab @code{netsh routing ip add persistentroute} @var{network_address} @var{netmask} @var{interface} @var{local_address}
2639 Adding routes to IPv6 subnets:
2641 @multitable {Darwin (MacOS/X)} {ifconfig route add -bla network address netmask netmask prefixlength interface}
2643 @tab @code{route add -A inet6} @var{network_address}@code{/}@var{prefixlength} @var{interface}
2644 @item Linux iproute2
2645 @tab @code{ip route add} @var{network_address}@code{/}@var{prefixlength} @code{dev} @var{interface}
2647 @tab @code{route add -inet6} @var{network_address}@code{/}@var{prefixlength} @var{local_address}
2649 @tab @code{route add -inet6} @var{network_address} @var{local_address} @code{-prefixlen} @var{prefixlength}
2651 @tab @code{route add -inet6} @var{network_address} @var{local_address} @code{-prefixlen} @var{prefixlength}
2653 @tab @code{route add -inet6} @var{network_address}@code{/}@var{prefixlength} @var{local_address} @code{-interface}
2654 @item Darwin (MacOS/X)
2657 @tab @code{netsh interface ipv6 add route} @var{network address}/@var{prefixlength} @var{interface}
2661 @c ==================================================================
2667 * Contact information::
2672 @c ==================================================================
2673 @node Contact information
2674 @section Contact information
2677 Tinc's website is at @url{http://www.tinc-vpn.org/},
2678 this server is located in the Netherlands.
2681 We have an IRC channel on the FreeNode and OFTC IRC networks. Connect to
2682 @uref{http://www.freenode.net/, irc.freenode.net}
2684 @uref{http://www.oftc.net/, irc.oftc.net}
2685 and join channel #tinc.
2688 @c ==================================================================
2693 @item Ivo Timmermans (zarq)
2694 @item Guus Sliepen (guus) (@email{guus@@tinc-vpn.org})
2697 We have received a lot of valuable input from users. With their help,
2698 tinc has become the flexible and robust tool that it is today. We have
2699 composed a list of contributions, in the file called @file{THANKS} in
2700 the source distribution.
2703 @c ==================================================================
2705 @unnumbered Concept Index
2707 @c ==================================================================
2711 @c ==================================================================