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{} 1998-2013 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{} 1998-2013 Ivo Timmermans,
43 Guus Sliepen <guus@@tinc-vpn.org> and
44 Wessel Dankers <wsl@@tinc-vpn.org>.
46 Permission is granted to make and distribute verbatim copies of this
47 manual provided the copyright notice and this permission notice are
48 preserved on all copies.
50 Permission is granted to copy and distribute modified versions of this
51 manual under the conditions for verbatim copying, provided that the
52 entire resulting derived work is distributed under the terms of a
53 permission notice identical to this one.
58 @c ==================================================================
68 * Technical information::
69 * Platform specific information::
71 * Concept Index:: All used terms explained
75 @c ==================================================================
80 Tinc is a Virtual Private Network (VPN) daemon that uses tunneling and
81 encryption to create a secure private network between hosts on the
84 Because the tunnel appears to the IP level network code as a normal
85 network device, there is no need to adapt any existing software.
86 The encrypted tunnels allows VPN sites to share information with each other
87 over the Internet without exposing any information to others.
89 This document is the manual for tinc. Included are chapters on how to
90 configure your computer to use tinc, as well as the configuration
91 process of tinc itself.
94 * Virtual Private Networks::
96 * Supported platforms::
99 @c ==================================================================
100 @node Virtual Private Networks
101 @section Virtual Private Networks
104 A Virtual Private Network or VPN is a network that can only be accessed
105 by a few elected computers that participate. This goal is achievable in
106 more than just one way.
109 Private networks can consist of a single stand-alone Ethernet LAN. Or
110 even two computers hooked up using a null-modem cable. In these cases,
112 obvious that the network is @emph{private}, no one can access it from the
113 outside. But if your computers are linked to the Internet, the network
114 is not private anymore, unless one uses firewalls to block all private
115 traffic. But then, there is no way to send private data to trusted
116 computers on the other end of the Internet.
119 This problem can be solved by using @emph{virtual} networks. Virtual
120 networks can live on top of other networks, but they use encapsulation to
121 keep using their private address space so they do not interfere with
122 the Internet. Mostly, virtual networks appear like a single LAN, even though
123 they can span the entire world. But virtual networks can't be secured
124 by using firewalls, because the traffic that flows through it has to go
125 through the Internet, where other people can look at it.
127 As is the case with either type of VPN, anybody could eavesdrop. Or
128 worse, alter data. Hence it's probably advisable to encrypt the data
129 that flows over the network.
131 When one introduces encryption, we can form a true VPN. Other people may
132 see encrypted traffic, but if they don't know how to decipher it (they
133 need to know the key for that), they cannot read the information that flows
134 through the VPN. This is what tinc was made for.
137 @c ==================================================================
142 I really don't quite remember what got us started, but it must have been
143 Guus' idea. He wrote a simple implementation (about 50 lines of C) that
144 used the ethertap device that Linux knows of since somewhere
145 about kernel 2.1.60. It didn't work immediately and he improved it a
146 bit. At this stage, the project was still simply called "vpnd".
148 Since then, a lot has changed---to say the least.
151 Tinc now supports encryption, it consists of a single daemon (tincd) for
152 both the receiving and sending end, it has become largely
153 runtime-configurable---in short, it has become a full-fledged
154 professional package.
156 @cindex traditional VPNs
158 Tinc also allows more than two sites to connect to eachother and form a single VPN.
159 Traditionally VPNs are created by making tunnels, which only have two endpoints.
160 Larger VPNs with more sites are created by adding more tunnels.
161 Tinc takes another approach: only endpoints are specified,
162 the software itself will take care of creating the tunnels.
163 This allows for easier configuration and improved scalability.
165 A lot can---and will be---changed. We have a number of things that we would like to
166 see in the future releases of tinc. Not everything will be available in
167 the near future. Our first objective is to make tinc work perfectly as
168 it stands, and then add more advanced features.
170 Meanwhile, we're always open-minded towards new ideas. And we're
174 @c ==================================================================
175 @node Supported platforms
176 @section Supported platforms
179 Tinc has been verified to work under Linux, FreeBSD, OpenBSD, NetBSD, MacOS/X (Darwin), Solaris, and Windows (both natively and in a Cygwin environment),
180 with various hardware architectures. These are some of the platforms
181 that are supported by the universal tun/tap device driver or other virtual network device drivers.
182 Without such a driver, tinc will most
183 likely compile and run, but it will not be able to send or receive data
187 For an up to date list of supported platforms, please check the list on
189 @uref{http://www.tinc-vpn.org/platforms/}.
197 @c Preparing your system
204 @c ==================================================================
206 @chapter Preparations
208 This chapter contains information on how to prepare your system to
212 * Configuring the kernel::
217 @c ==================================================================
218 @node Configuring the kernel
219 @section Configuring the kernel
222 * Configuration of Linux kernels::
223 * Configuration of FreeBSD kernels::
224 * Configuration of OpenBSD kernels::
225 * Configuration of NetBSD kernels::
226 * Configuration of Solaris kernels::
227 * Configuration of Darwin (MacOS/X) kernels::
228 * Configuration of Windows::
232 @c ==================================================================
233 @node Configuration of Linux kernels
234 @subsection Configuration of Linux kernels
236 @cindex Universal tun/tap
237 For tinc to work, you need a kernel that supports the Universal tun/tap device.
238 Most distributions come with kernels that already support this.
239 Here are the options you have to turn on when configuring a new kernel:
242 Code maturity level options
243 [*] Prompt for development and/or incomplete code/drivers
244 Network device support
245 <M> Universal tun/tap device driver support
248 It's not necessary to compile this driver as a module, even if you are going to
249 run more than one instance of tinc.
251 If you decide to build the tun/tap driver as a kernel module, add these lines
252 to @file{/etc/modules.conf}:
255 alias char-major-10-200 tun
259 @c ==================================================================
260 @node Configuration of FreeBSD kernels
261 @subsection Configuration of FreeBSD kernels
263 For FreeBSD version 4.1 and higher, tun and tap drivers are included in the default kernel configuration.
264 The tap driver can be loaded with @code{kldload if_tap}, or by adding @code{if_tap_load="YES"} to @file{/boot/loader.conf}.
267 @c ==================================================================
268 @node Configuration of OpenBSD kernels
269 @subsection Configuration of OpenBSD kernels
271 For OpenBSD version 2.9 and higher,
272 the tun driver is included in the default kernel configuration.
273 There is also a kernel patch from @uref{http://diehard.n-r-g.com/stuff/openbsd/}
274 which adds a tap device to OpenBSD which should work with tinc,
275 but with recent versions of OpenBSD,
276 a tun device can act as a tap device by setting the link0 option with ifconfig.
279 @c ==================================================================
280 @node Configuration of NetBSD kernels
281 @subsection Configuration of NetBSD kernels
283 For NetBSD version 1.5.2 and higher,
284 the tun driver is included in the default kernel configuration.
286 Tunneling IPv6 may not work on NetBSD's tun device.
289 @c ==================================================================
290 @node Configuration of Solaris kernels
291 @subsection Configuration of Solaris kernels
293 For Solaris 8 (SunOS 5.8) and higher,
294 the tun driver may or may not be included in the default kernel configuration.
295 If it isn't, the source can be downloaded from @uref{http://vtun.sourceforge.net/tun/}.
296 For x86 and sparc64 architectures, precompiled versions can be found at @uref{http://www.monkey.org/~dugsong/fragroute/}.
297 If the @file{net/if_tun.h} header file is missing, install it from the source package.
300 @c ==================================================================
301 @node Configuration of Darwin (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.
344 @c ==================================================================
349 For all cryptography-related functions, tinc uses the functions provided
350 by the OpenSSL library.
352 If this library is not installed, you wil get an error when configuring
353 tinc for build. Support for running tinc with other cryptographic libraries
354 installed @emph{may} be added in the future.
356 You can use your operating system's package manager to install this if
357 available. Make sure you install the development AND runtime versions
360 If you have to install OpenSSL manually, you can get the source code
361 from @url{http://www.openssl.org/}. Instructions on how to configure,
362 build and install this package are included within the package. Please
363 make sure you build development and runtime libraries (which is the
366 If you installed the OpenSSL libraries from source, it may be necessary
367 to let configure know where they are, by passing configure one of the
368 --with-openssl-* parameters.
371 --with-openssl=DIR OpenSSL library and headers prefix
372 --with-openssl-include=DIR OpenSSL headers directory
373 (Default is OPENSSL_DIR/include)
374 --with-openssl-lib=DIR OpenSSL library directory
375 (Default is OPENSSL_DIR/lib)
379 @subsubheading License
382 The complete source code of tinc is covered by the GNU GPL version 2.
383 Since the license under which OpenSSL is distributed is not directly
384 compatible with the terms of the GNU GPL
385 @uref{http://www.openssl.org/support/faq.html#LEGAL2}, we
386 include an exemption to the GPL (see also the file COPYING.README) to allow
387 everyone to create a statically or dynamically linked executable:
390 This program is released under the GPL with the additional exemption
391 that compiling, linking, and/or using OpenSSL is allowed. You may
392 provide binary packages linked to the OpenSSL libraries, provided that
393 all other requirements of the GPL are met.
396 Since the LZO library used by tinc is also covered by the GPL,
397 we also present the following exemption:
400 Hereby I grant a special exception to the tinc VPN project
401 (http://www.tinc-vpn.org/) to link the LZO library with the OpenSSL library
402 (http://www.openssl.org).
404 Markus F.X.J. Oberhumer
408 @c ==================================================================
413 For the optional compression of UDP packets, tinc uses the functions provided
416 If this library is not installed, you wil get an error when running the
417 configure script. You can either install the zlib library, or disable support
418 for zlib compression by using the "--disable-zlib" option when running the
419 configure script. Note that if you disable support for zlib, the resulting
420 binary will not work correctly on VPNs where zlib compression is used.
422 You can use your operating system's package manager to install this if
423 available. Make sure you install the development AND runtime versions
426 If you have to install zlib manually, you can get the source code
427 from @url{http://www.gzip.org/zlib/}. Instructions on how to configure,
428 build and install this package are included within the package. Please
429 make sure you build development and runtime libraries (which is the
433 @c ==================================================================
438 Another form of compression is offered using the LZO library.
440 If this library is not installed, you wil get an error when running the
441 configure script. You can either install the LZO library, or disable support
442 for LZO compression by using the "--disable-lzo" option when running the
443 configure script. Note that if you disable support for LZO, the resulting
444 binary will not work correctly on VPNs where LZO compression is used.
446 You can use your operating system's package manager to install this if
447 available. Make sure you install the development AND runtime versions
450 If you have to install lzo manually, you can get the source code
451 from @url{http://www.oberhumer.com/opensource/lzo/}. Instructions on how to configure,
452 build and install this package are included within the package. Please
453 make sure you build development and runtime libraries (which is the
466 @c ==================================================================
468 @chapter Installation
470 If you use Debian, you may want to install one of the
471 precompiled packages for your system. These packages are equipped with
472 system startup scripts and sample configurations.
474 If you cannot use one of the precompiled packages, or you want to compile tinc
475 for yourself, you can use the source. The source is distributed under
476 the GNU General Public License (GPL). Download the source from the
477 @uref{http://www.tinc-vpn.org/download/, download page}, which has
478 the checksums of these files listed; you may wish to check these with
479 md5sum before continuing.
481 Tinc comes in a convenient autoconf/automake package, which you can just
482 treat the same as any other package. Which is just untar it, type
483 `./configure' and then `make'.
484 More detailed instructions are in the file @file{INSTALL}, which is
485 included in the source distribution.
488 * Building and installing tinc::
493 @c ==================================================================
494 @node Building and installing tinc
495 @section Building and installing tinc
497 Detailed instructions on configuring the source, building tinc and installing tinc
498 can be found in the file called @file{INSTALL}.
500 @cindex binary package
501 If you happen to have a binary package for tinc for your distribution,
502 you can use the package management tools of that distribution to install tinc.
503 The documentation that comes along with your distribution will tell you how to do that.
506 * Darwin (MacOS/X) build environment::
507 * Cygwin (Windows) build environment::
508 * MinGW (Windows) build environment::
512 @c ==================================================================
513 @node Darwin (MacOS/X) build environment
514 @subsection Darwin (MacOS/X) build environment
516 In order to build tinc on Darwin, you need to install the MacOS/X Developer Tools
517 from @uref{http://developer.apple.com/tools/macosxtools.html} and
518 a recent version of Fink from @uref{http://www.finkproject.org/}.
520 After installation use fink to download and install the following packages:
521 autoconf25, automake, dlcompat, m4, openssl, zlib and lzo.
523 @c ==================================================================
524 @node Cygwin (Windows) build environment
525 @subsection Cygwin (Windows) build environment
527 If Cygwin hasn't already been installed, install it directly from
528 @uref{http://www.cygwin.com/}.
530 When tinc is compiled in a Cygwin environment, it can only be run in this environment,
531 but all programs, including those started outside the Cygwin environment, will be able to use the VPN.
532 It will also support all features.
534 @c ==================================================================
535 @node MinGW (Windows) build environment
536 @subsection MinGW (Windows) build environment
538 You will need to install the MinGW environment from @uref{http://www.mingw.org}.
540 When tinc is compiled using MinGW it runs natively under Windows,
541 it is not necessary to keep MinGW installed.
543 When detaching, tinc will install itself as a service,
544 which will be restarted automatically after reboots.
547 @c ==================================================================
549 @section System files
551 Before you can run tinc, you must make sure you have all the needed
552 files on your system.
560 @c ==================================================================
562 @subsection Device files
565 Most operating systems nowadays come with the necessary device files by default,
566 or they have a mechanism to create them on demand.
568 If you use Linux and do not have udev installed,
569 you may need to create the following device file if it does not exist:
572 mknod -m 600 /dev/net/tun c 10 200
576 @c ==================================================================
578 @subsection Other files
580 @subsubheading @file{/etc/networks}
582 You may add a line to @file{/etc/networks} so that your VPN will get a
583 symbolic name. For example:
589 @subsubheading @file{/etc/services}
592 You may add this line to @file{/etc/services}. The effect is that you
593 may supply a @samp{tinc} as a valid port number to some programs. The
594 number 655 is registered with the IANA.
599 # Ivo Timmermans <ivo@@tinc-vpn.org>
614 @c ==================================================================
616 @chapter Configuration
619 * Configuration introduction::
620 * Multiple networks::
621 * How connections work::
622 * Configuration files::
623 * Generating keypairs::
624 * Network interfaces::
625 * Example configuration::
628 @c ==================================================================
629 @node Configuration introduction
630 @section Configuration introduction
632 Before actually starting to configure tinc and editing files,
633 make sure you have read this entire section so you know what to expect.
634 Then, make it clear to yourself how you want to organize your VPN:
635 What are the nodes (computers running tinc)?
636 What IP addresses/subnets do they have?
637 What is the network mask of the entire VPN?
638 Do you need special firewall rules?
639 Do you have to set up masquerading or forwarding rules?
640 Do you want to run tinc in router mode or switch mode?
641 These questions can only be answered by yourself,
642 you will not find the answers in this documentation.
643 Make sure you have an adequate understanding of networks in general.
644 @cindex Network Administrators Guide
645 A good resource on networking is the
646 @uref{http://www.tldp.org/LDP/nag2/, Linux Network Administrators Guide}.
648 If you have everything clearly pictured in your mind,
649 proceed in the following order:
650 First, generate the configuration files (@file{tinc.conf}, your host configuration file, @file{tinc-up} and perhaps @file{tinc-down}).
651 Then generate the keypairs.
652 Finally, distribute the host configuration files.
653 These steps are described in the subsections below.
656 @c ==================================================================
657 @node Multiple networks
658 @section Multiple networks
660 @cindex multiple networks
662 In order to allow you to run more than one tinc daemon on one computer,
663 for instance if your computer is part of more than one VPN,
664 you can assign a @var{netname} to your VPN.
665 It is not required if you only run one tinc daemon,
666 it doesn't even have to be the same on all the sites of your VPN,
667 but it is recommended that you choose one anyway.
669 We will asume you use a netname throughout this document.
670 This means that you call tincd with the -n argument,
671 which will assign a netname to this daemon.
673 The effect of this is that the daemon will set its configuration
674 root to @file{@value{sysconfdir}/tinc/@var{netname}/}, where @var{netname} is your argument to the -n
675 option. You'll notice that it appears in syslog as @file{tinc.@var{netname}}.
677 However, it is not strictly necessary that you call tinc with the -n
678 option. In this case, the network name would just be empty, and it will
679 be used as such. tinc now looks for files in @file{@value{sysconfdir}/tinc/}, instead of
680 @file{@value{sysconfdir}/tinc/@var{netname}/}; the configuration file should be @file{@value{sysconfdir}/tinc/tinc.conf},
681 and the host configuration files are now expected to be in @file{@value{sysconfdir}/tinc/hosts/}.
683 But it is highly recommended that you use this feature of tinc, because
684 it will be so much clearer whom your daemon talks to. Hence, we will
685 assume that you use it.
688 @c ==================================================================
689 @node How connections work
690 @section How connections work
692 When tinc starts up, it parses the command-line options and then
693 reads in the configuration file tinc.conf.
694 If it sees one or more `ConnectTo' values pointing to other tinc daemons in that file,
695 it will try to connect to those other daemons.
696 Whether this succeeds or not and whether `ConnectTo' is specified or not,
697 tinc will listen for incoming connection from other deamons.
698 If you did specify a `ConnectTo' value and the other side is not responding,
699 tinc will keep retrying.
700 This means that once started, tinc will stay running until you tell it to stop,
701 and failures to connect to other tinc daemons will not stop your tinc daemon
702 for trying again later.
703 This means you don't have to intervene if there are temporary network problems.
707 There is no real distinction between a server and a client in tinc.
708 If you wish, you can view a tinc daemon without a `ConnectTo' value as a server,
709 and one which does specify such a value as a client.
710 It does not matter if two tinc daemons have a `ConnectTo' value pointing to each other however.
713 @c ==================================================================
714 @node Configuration files
715 @section Configuration files
717 The actual configuration of the daemon is done in the file
718 @file{@value{sysconfdir}/tinc/@var{netname}/tinc.conf} and at least one other file in the directory
719 @file{@value{sysconfdir}/tinc/@var{netname}/hosts/}.
721 An optionnal directory @file{@value{sysconfdir}/tinc/@var{netname}/conf.d} can be added from which
722 any .conf file will be read.
724 These file consists of comments (lines started with a #) or assignments
731 The variable names are case insensitive, and any spaces, tabs, newlines
732 and carriage returns are ignored. Note: it is not required that you put
733 in the `=' sign, but doing so improves readability. If you leave it
734 out, remember to replace it with at least one space character.
736 The server configuration is complemented with host specific configuration (see
737 the next section). Although all host configuration options for the local node
738 listed in this document can also be put in
739 @file{@value{sysconfdir}/tinc/@var{netname}/tinc.conf}, it is recommended to
740 put host specific configuration options in the host configuration file, as this
741 makes it easy to exchange with other nodes.
743 In this section all valid variables are listed in alphabetical order.
744 The default value is given between parentheses,
745 other comments are between square brackets.
748 * Main configuration variables::
749 * Host configuration variables::
755 @c ==================================================================
756 @node Main configuration variables
757 @subsection Main configuration variables
760 @cindex AddressFamily
761 @item AddressFamily = <ipv4|ipv6|any> (any)
762 This option affects the address family of listening and outgoing sockets.
763 If any is selected, then depending on the operating system
764 both IPv4 and IPv6 or just IPv6 listening sockets will be created.
766 @cindex BindToAddress
767 @item BindToAddress = <@var{address}> [<@var{port}>] [experimental]
768 If your computer has more than one IPv4 or IPv6 address, tinc
769 will by default listen on all of them for incoming connections.
770 Multiple BindToAddress variables may be specified,
771 in which case listening sockets for each specified address are made.
773 If no @var{port} is specified, the socket will be bound to the port specified by the Port option,
774 or to port 655 if neither is given.
775 To only bind to a specific port but not to a specific address, use "*" for the @var{address}.
777 This option may not work on all platforms.
779 @cindex BindToInterface
780 @item BindToInterface = <@var{interface}> [experimental]
781 If you have more than one network interface in your computer, tinc will
782 by default listen on all of them for incoming connections. It is
783 possible to bind tinc to a single interface like eth0 or ppp0 with this
786 This option may not work on all platforms.
789 @item Broadcast = <no | mst | direct> (mst) [experimental]
790 This option selects the way broadcast packets are sent to other daemons.
791 @emph{NOTE: all nodes in a VPN must use the same Broadcast mode, otherwise routing loops can form.}
795 Broadcast packets are never sent to other nodes.
798 Broadcast packets are sent and forwarded via the VPN's Minimum Spanning Tree.
799 This ensures broadcast packets reach all nodes.
802 Broadcast packets are sent directly to all nodes that can be reached directly.
803 Broadcast packets received from other nodes are never forwarded.
804 If the IndirectData option is also set, broadcast packets will only be sent to nodes which we have a meta connection to.
808 @item ConnectTo = <@var{name}>
809 Specifies which other tinc daemon to connect to on startup.
810 Multiple ConnectTo variables may be specified,
811 in which case outgoing connections to each specified tinc daemon are made.
812 The names should be known to this tinc daemon
813 (i.e., there should be a host configuration file for the name on the ConnectTo line).
815 If you don't specify a host with ConnectTo,
816 tinc won't try to connect to other daemons at all,
817 and will instead just listen for incoming connections.
820 @item DecrementTTL = <yes | no> (no) [experimental]
821 When enabled, tinc will decrement the Time To Live field in IPv4 packets, or the Hop Limit field in IPv6 packets,
822 before forwarding a received packet to the virtual network device or to another node,
823 and will drop packets that have a TTL value of zero,
824 in which case it will send an ICMP Time Exceeded packet back.
826 Do not use this option if you use switch mode and want to use IPv6.
829 @item Device = <@var{device}> (@file{/dev/tap0}, @file{/dev/net/tun} or other depending on platform)
830 The virtual network device to use.
831 Tinc will automatically detect what kind of device it is.
832 Note that you can only use one device per daemon.
833 Under Windows, use @var{Interface} instead of @var{Device}.
834 Note that you can only use one device per daemon.
835 See also @ref{Device files}.
838 @item DeviceType = <@var{type}> (platform dependent)
839 The type of the virtual network device.
840 Tinc will normally automatically select the right type of tun/tap interface, and this option should not be used.
841 However, this option can be used to select one of the special interface types, if support for them is compiled in.
846 Use a dummy interface.
847 No packets are ever read or written to a virtual network device.
848 Useful for testing, or when setting up a node that only forwards packets for other nodes.
852 Open a raw socket, and bind it to a pre-existing
853 @var{Interface} (eth0 by default).
854 All packets are read from this interface.
855 Packets received for the local node are written to the raw socket.
856 However, at least on Linux, the operating system does not process IP packets destined for the local host.
860 Open a multicast UDP socket and bind it to the address and port (separated by spaces) and optionally a TTL value specified using @var{Device}.
861 Packets are read from and written to this multicast socket.
862 This can be used to connect to UML, QEMU or KVM instances listening on the same multicast address.
863 Do NOT connect multiple tinc daemons to the same multicast address, this will very likely cause routing loops.
864 Also note that this can cause decrypted VPN packets to be sent out on a real network if misconfigured.
867 @item uml (not compiled in by default)
868 Create a UNIX socket with the filename specified by
869 @var{Device}, or @file{@value{localstatedir}/run/@var{netname}.umlsocket}
871 Tinc will wait for a User Mode Linux instance to connect to this socket.
874 @item vde (not compiled in by default)
875 Uses the libvdeplug library to connect to a Virtual Distributed Ethernet switch,
876 using the UNIX socket specified by
877 @var{Device}, or @file{@value{localstatedir}/run/vde.ctl}
881 Also, in case tinc does not seem to correctly interpret packets received from the virtual network device,
882 it can be used to change the way packets are interpreted:
885 @item tun (BSD and Linux)
887 Depending on the platform, this can either be with or without an address family header (see below).
890 @item tunnohead (BSD)
891 Set type to tun without an address family header.
892 Tinc will expect packets read from the virtual network device to start with an IP header.
893 On some platforms IPv6 packets cannot be read from or written to the device in this mode.
896 @item tunifhead (BSD)
897 Set type to tun with an address family header.
898 Tinc will expect packets read from the virtual network device
899 to start with a four byte header containing the address family,
900 followed by an IP header.
901 This mode should support both IPv4 and IPv6 packets.
903 @item tap (BSD and Linux)
905 Tinc will expect packets read from the virtual network device
906 to start with an Ethernet header.
910 @item DirectOnly = <yes|no> (no) [experimental]
911 When this option is enabled, packets that cannot be sent directly to the destination node,
912 but which would have to be forwarded by an intermediate node, are dropped instead.
913 When combined with the IndirectData option,
914 packets for nodes for which we do not have a meta connection with are also dropped.
917 @item Forwarding = <off|internal|kernel> (internal) [experimental]
918 This option selects the way indirect packets are forwarded.
922 Incoming packets that are not meant for the local node,
923 but which should be forwarded to another node, are dropped.
926 Incoming packets that are meant for another node are forwarded by tinc internally.
928 This is the default mode, and unless you really know you need another forwarding mode, don't change it.
931 Incoming packets are always sent to the TUN/TAP device, even if the packets are not for the local node.
932 This is less efficient, but allows the kernel to apply its routing and firewall rules on them,
933 and can also help debugging.
936 @cindex GraphDumpFile
937 @item GraphDumpFile = <@var{filename}> [experimental]
938 If this option is present,
939 tinc will dump the current network graph to the file @var{filename}
940 every minute, unless there were no changes to the graph.
941 The file is in a format that can be read by graphviz tools.
942 If @var{filename} starts with a pipe symbol |,
943 then the rest of the filename is interpreted as a shell command
944 that is executed, the graph is then sent to stdin.
947 @item Hostnames = <yes|no> (no)
948 This option selects whether IP addresses (both real and on the VPN)
949 should be resolved. Since DNS lookups are blocking, it might affect
950 tinc's efficiency, even stopping the daemon for a few seconds everytime
951 it does a lookup if your DNS server is not responding.
953 This does not affect resolving hostnames to IP addresses from the
954 configuration file, but whether hostnames should be resolved while logging.
957 @item IffOneQueue = <yes|no> (no) [experimental]
958 (Linux only) Set IFF_ONE_QUEUE flag on TUN/TAP devices.
961 @item Interface = <@var{interface}>
962 Defines the name of the interface corresponding to the virtual network device.
963 Depending on the operating system and the type of device this may or may not actually set the name of the interface.
964 Under Windows, this variable is used to select which network interface will be used.
965 If you specified a Device, this variable is almost always already correctly set.
968 @item KeyExpire = <@var{seconds}> (3600)
969 This option controls the time the encryption keys used to encrypt the data
970 are valid. It is common practice to change keys at regular intervals to
971 make it even harder for crackers, even though it is thought to be nearly
972 impossible to crack a single key.
974 @cindex LocalDiscovery
975 @item LocalDiscovery = <yes | no> (no) [experimental]
976 When enabled, tinc will try to detect peers that are on the same local network.
977 This will allow direct communication using LAN addresses, even if both peers are behind a NAT
978 and they only ConnectTo a third node outside the NAT,
979 which normally would prevent the peers from learning each other's LAN address.
981 Currently, local discovery is implemented by sending broadcast packets to the LAN during path MTU discovery.
982 This feature may not work in all possible situations.
985 @item MACExpire = <@var{seconds}> (600)
986 This option controls the amount of time MAC addresses are kept before they are removed.
987 This only has effect when Mode is set to "switch".
990 @item MaxTimeout = <@var{seconds}> (900)
991 This is the maximum delay before trying to reconnect to other tinc daemons.
994 @item Mode = <router|switch|hub> (router)
995 This option selects the way packets are routed to other daemons.
1001 variables in the host configuration files will be used to form a routing table.
1002 Only unicast packets of routable protocols (IPv4 and IPv6) are supported in this mode.
1004 This is the default mode, and unless you really know you need another mode, don't change it.
1008 In this mode the MAC addresses of the packets on the VPN will be used to
1009 dynamically create a routing table just like an Ethernet switch does.
1010 Unicast, multicast and broadcast packets of every protocol that runs over Ethernet are supported in this mode
1011 at the cost of frequent broadcast ARP requests and routing table updates.
1013 This mode is primarily useful if you want to bridge Ethernet segments.
1017 This mode is almost the same as the switch mode, but instead
1018 every packet will be broadcast to the other daemons
1019 while no routing table is managed.
1023 @item Name = <@var{name}> [required]
1024 This is a symbolic name for this connection.
1025 The name should consist only of alfanumeric and underscore characters (a-z, A-Z, 0-9 and _).
1027 If Name starts with a $, then the contents of the environment variable that follows will be used.
1028 In that case, invalid characters will be converted to underscores.
1029 If Name is $HOST, but no such environment variable exist,
1030 the hostname will be read using the gethostnname() system call.
1032 @cindex PingInterval
1033 @item PingInterval = <@var{seconds}> (60)
1034 The number of seconds of inactivity that tinc will wait before sending a
1035 probe to the other end.
1038 @item PingTimeout = <@var{seconds}> (5)
1039 The number of seconds to wait for a response to pings or to allow meta
1040 connections to block. If the other end doesn't respond within this time,
1041 the connection is terminated, and the others will be notified of this.
1043 @cindex PriorityInheritance
1044 @item PriorityInheritance = <yes|no> (no) [experimental]
1045 When this option is enabled the value of the TOS field of tunneled IPv4 packets
1046 will be inherited by the UDP packets that are sent out.
1049 @item PrivateKey = <@var{key}> [obsolete]
1050 This is the RSA private key for tinc. However, for safety reasons it is
1051 advised to store private keys of any kind in separate files. This prevents
1052 accidental eavesdropping if you are editting the configuration file.
1054 @cindex PrivateKeyFile
1055 @item PrivateKeyFile = <@var{path}> (@file{@value{sysconfdir}/tinc/@var{netname}/rsa_key.priv})
1056 This is the full path name of the RSA private key file that was
1057 generated by @samp{tincd --generate-keys}. It must be a full path, not a
1060 @cindex ProcessPriority
1061 @item ProcessPriority = <low|normal|high>
1062 When this option is used the priority of the tincd process will be adjusted.
1063 Increasing the priority may help to reduce latency and packet loss on the VPN.
1066 @item Proxy = socks4 | socks5 | http | exec @var{...} [experimental]
1067 Use a proxy when making outgoing connections.
1068 The following proxy types are currently supported:
1072 @item socks4 <@var{address}> <@var{port}> [<@var{username}>]
1073 Connects to the proxy using the SOCKS version 4 protocol.
1074 Optionally, a @var{username} can be supplied which will be passed on to the proxy server.
1077 @item socks5 <@var{address}> <@var{port}> [<@var{username}> <@var{password}>]
1078 Connect to the proxy using the SOCKS version 5 protocol.
1079 If a @var{username} and @var{password} are given, basic username/password authentication will be used,
1080 otherwise no authentication will be used.
1083 @item http <@var{address}> <@var{port}>
1084 Connects to the proxy and sends a HTTP CONNECT request.
1087 @item exec <@var{command}>
1088 Executes the given command which should set up the outgoing connection.
1089 The environment variables @env{NAME}, @env{NODE}, @env{REMOTEADDRES} and @env{REMOTEPORT} are available.
1092 @cindex ReplayWindow
1093 @item ReplayWindow = <bytes> (16)
1094 This is the size of the replay tracking window for each remote node, in bytes.
1095 The window is a bitfield which tracks 1 packet per bit, so for example
1096 the default setting of 16 will track up to 128 packets in the window. In high
1097 bandwidth scenarios, setting this to a higher value can reduce packet loss from
1098 the interaction of replay tracking with underlying real packet loss and/or
1099 reordering. Setting this to zero will disable replay tracking completely and
1100 pass all traffic, but leaves tinc vulnerable to replay-based attacks on your
1103 @cindex StrictSubnets
1104 @item StrictSubnets = <yes|no> (no) [experimental]
1105 When this option is enabled tinc will only use Subnet statements which are
1106 present in the host config files in the local
1107 @file{@value{sysconfdir}/tinc/@var{netname}/hosts/} directory.
1109 @cindex TunnelServer
1110 @item TunnelServer = <yes|no> (no) [experimental]
1111 When this option is enabled tinc will no longer forward information between other tinc daemons,
1112 and will only allow connections with nodes for which host config files are present in the local
1113 @file{@value{sysconfdir}/tinc/@var{netname}/hosts/} directory.
1114 Setting this options also implicitly sets StrictSubnets.
1117 @item UDPRcvBuf = <bytes> (OS default)
1118 Sets the socket receive buffer size for the UDP socket, in bytes.
1119 If unset, the default buffer size will be used by the operating system.
1122 @item UDPSndBuf = <bytes> Pq OS default
1123 Sets the socket send buffer size for the UDP socket, in bytes.
1124 If unset, the default buffer size will be used by the operating system.
1129 @c ==================================================================
1130 @node Host configuration variables
1131 @subsection Host configuration variables
1135 @item Address = <@var{IP address}|@var{hostname}> [<port>] [recommended]
1136 This variable is only required if you want to connect to this host. It
1137 must resolve to the external IP address where the host can be reached,
1138 not the one that is internal to the VPN.
1139 If no port is specified, the default Port is used.
1140 Multiple Address variables can be specified, in which case each address will be
1141 tried until a working connection has been established.
1144 @item Cipher = <@var{cipher}> (blowfish)
1145 The symmetric cipher algorithm used to encrypt UDP packets.
1146 Any cipher supported by OpenSSL is recognized.
1147 Furthermore, specifying "none" will turn off packet encryption.
1148 It is best to use only those ciphers which support CBC mode.
1151 @item ClampMSS = <yes|no> (yes)
1152 This option specifies whether tinc should clamp the maximum segment size (MSS)
1153 of TCP packets to the path MTU. This helps in situations where ICMP
1154 Fragmentation Needed or Packet too Big messages are dropped by firewalls.
1157 @item Compression = <@var{level}> (0)
1158 This option sets the level of compression used for UDP packets.
1159 Possible values are 0 (off), 1 (fast zlib) and any integer up to 9 (best zlib),
1160 10 (fast lzo) and 11 (best lzo).
1163 @item Digest = <@var{digest}> (sha1)
1164 The digest algorithm used to authenticate UDP packets.
1165 Any digest supported by OpenSSL is recognized.
1166 Furthermore, specifying "none" will turn off packet authentication.
1168 @cindex IndirectData
1169 @item IndirectData = <yes|no> (no)
1170 This option specifies whether other tinc daemons besides the one you
1171 specified with ConnectTo can make a direct connection to you. This is
1172 especially useful if you are behind a firewall and it is impossible to
1173 make a connection from the outside to your tinc daemon. Otherwise, it
1174 is best to leave this option out or set it to no.
1177 @item MACLength = <@var{bytes}> (4)
1178 The length of the message authentication code used to authenticate UDP packets.
1179 Can be anything from 0
1180 up to the length of the digest produced by the digest algorithm.
1183 @item PMTU = <@var{mtu}> (1514)
1184 This option controls the initial path MTU to this node.
1186 @cindex PMTUDiscovery
1187 @item PMTUDiscovery = <yes|no> (yes)
1188 When this option is enabled, tinc will try to discover the path MTU to this node.
1189 After the path MTU has been discovered, it will be enforced on the VPN.
1192 @item Port = <@var{port}> (655)
1193 This is the port this tinc daemon listens on.
1194 You can use decimal portnumbers or symbolic names (as listed in @file{/etc/services}).
1197 @item PublicKey = <@var{key}> [obsolete]
1198 This is the RSA public key for this host.
1200 @cindex PublicKeyFile
1201 @item PublicKeyFile = <@var{path}> [obsolete]
1202 This is the full path name of the RSA public key file that was generated
1203 by @samp{tincd --generate-keys}. It must be a full path, not a relative
1207 From version 1.0pre4 on tinc will store the public key directly into the
1208 host configuration file in PEM format, the above two options then are not
1209 necessary. Either the PEM format is used, or exactly
1210 @strong{one of the above two options} must be specified
1211 in each host configuration file, if you want to be able to establish a
1212 connection with that host.
1215 @item Subnet = <@var{address}[/@var{prefixlength}[#@var{weight}]]>
1216 The subnet which this tinc daemon will serve.
1217 Tinc tries to look up which other daemon it should send a packet to by searching the appropiate subnet.
1218 If the packet matches a subnet,
1219 it will be sent to the daemon who has this subnet in his host configuration file.
1220 Multiple subnet lines can be specified for each daemon.
1222 Subnets can either be single MAC, IPv4 or IPv6 addresses,
1223 in which case a subnet consisting of only that single address is assumed,
1224 or they can be a IPv4 or IPv6 network address with a prefixlength.
1225 For example, IPv4 subnets must be in a form like 192.168.1.0/24,
1226 where 192.168.1.0 is the network address and 24 is the number of bits set in the netmask.
1227 Note that subnets like 192.168.1.1/24 are invalid!
1228 Read a networking HOWTO/FAQ/guide if you don't understand this.
1229 IPv6 subnets are notated like fec0:0:0:1::/64.
1230 MAC addresses are notated like 0:1a:2b:3c:4d:5e.
1232 @cindex CIDR notation
1233 Prefixlength is the number of bits set to 1 in the netmask part; for
1234 example: netmask 255.255.255.0 would become /24, 255.255.252.0 becomes
1235 /22. This conforms to standard CIDR notation as described in
1236 @uref{http://www.ietf.org/rfc/rfc1519.txt, RFC1519}
1238 @cindex Subnet weight
1239 A Subnet can be given a weight to indicate its priority over identical Subnets
1240 owned by different nodes. The default weight is 10. Lower values indicate
1241 higher priority. Packets will be sent to the node with the highest priority,
1242 unless that node is not reachable, in which case the node with the next highest
1243 priority will be tried, and so on.
1246 @item TCPonly = <yes|no> (no) [deprecated]
1247 If this variable is set to yes, then the packets are tunnelled over a
1248 TCP connection instead of a UDP connection. This is especially useful
1249 for those who want to run a tinc daemon from behind a masquerading
1250 firewall, or if UDP packet routing is disabled somehow.
1251 Setting this options also implicitly sets IndirectData.
1253 Since version 1.0.10, tinc will automatically detect whether communication via
1254 UDP is possible or not.
1258 @c ==================================================================
1263 Apart from reading the server and host configuration files,
1264 tinc can also run scripts at certain moments.
1265 Under Windows (not Cygwin), the scripts should have the extension .bat.
1269 @item @value{sysconfdir}/tinc/@var{netname}/tinc-up
1270 This is the most important script.
1271 If it is present it will be executed right after the tinc daemon has been
1272 started and has connected to the virtual network device.
1273 It should be used to set up the corresponding network interface,
1274 but can also be used to start other things.
1275 Under Windows you can use the Network Connections control panel instead of creating this script.
1278 @item @value{sysconfdir}/tinc/@var{netname}/tinc-down
1279 This script is started right before the tinc daemon quits.
1281 @item @value{sysconfdir}/tinc/@var{netname}/hosts/@var{host}-up
1282 This script is started when the tinc daemon with name @var{host} becomes reachable.
1284 @item @value{sysconfdir}/tinc/@var{netname}/hosts/@var{host}-down
1285 This script is started when the tinc daemon with name @var{host} becomes unreachable.
1287 @item @value{sysconfdir}/tinc/@var{netname}/host-up
1288 This script is started when any host becomes reachable.
1290 @item @value{sysconfdir}/tinc/@var{netname}/host-down
1291 This script is started when any host becomes unreachable.
1293 @item @value{sysconfdir}/tinc/@var{netname}/subnet-up
1294 This script is started when a Subnet becomes reachable.
1295 The Subnet and the node it belongs to are passed in environment variables.
1297 @item @value{sysconfdir}/tinc/@var{netname}/subnet-down
1298 This script is started when a Subnet becomes unreachable.
1301 @cindex environment variables
1302 The scripts are started without command line arguments,
1303 but can make use of certain environment variables.
1304 Under UNIX like operating systems the names of environment variables must be preceded by a $ in scripts.
1305 Under Windows, in @file{.bat} files, they have to be put between % signs.
1310 If a netname was specified, this environment variable contains it.
1314 Contains the name of this tinc daemon.
1318 Contains the name of the virtual network device that tinc uses.
1322 Contains the name of the virtual network interface that tinc uses.
1323 This should be used for commands like ifconfig.
1327 When a host becomes (un)reachable, this is set to its name.
1328 If a subnet becomes (un)reachable, this is set to the owner of that subnet.
1330 @cindex REMOTEADDRESS
1332 When a host becomes (un)reachable, this is set to its real address.
1336 When a host becomes (un)reachable,
1337 this is set to the port number it uses for communication with other tinc daemons.
1341 When a subnet becomes (un)reachable, this is set to the subnet.
1345 When a subnet becomes (un)reachable, this is set to the subnet weight.
1350 @c ==================================================================
1351 @node How to configure
1352 @subsection How to configure
1354 @subsubheading Step 1. Creating the main configuration file
1356 The main configuration file will be called @file{@value{sysconfdir}/tinc/@var{netname}/tinc.conf}.
1357 Adapt the following example to create a basic configuration file:
1360 Name = @var{yourname}
1361 Device = @file{/dev/tap0}
1364 Then, if you know to which other tinc daemon(s) yours is going to connect,
1365 add `ConnectTo' values.
1367 @subsubheading Step 2. Creating your host configuration file
1369 If you added a line containing `Name = yourname' in the main configuarion file,
1370 you will need to create a host configuration file @file{@value{sysconfdir}/tinc/@var{netname}/hosts/yourname}.
1371 Adapt the following example to create a host configuration file:
1374 Address = your.real.hostname.org
1375 Subnet = 192.168.1.0/24
1378 You can also use an IP address instead of a hostname.
1379 The `Subnet' specifies the address range that is local for @emph{your part of the VPN only}.
1380 If you have multiple address ranges you can specify more than one `Subnet'.
1381 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).
1384 @c ==================================================================
1385 @node Generating keypairs
1386 @section Generating keypairs
1388 @cindex key generation
1389 Now that you have already created the main configuration file and your host configuration file,
1390 you can easily create a public/private keypair by entering the following command:
1393 tincd -n @var{netname} -K
1396 Tinc will generate a public and a private key and ask you where to put them.
1397 Just press enter to accept the defaults.
1400 @c ==================================================================
1401 @node Network interfaces
1402 @section Network interfaces
1404 Before tinc can start transmitting data over the tunnel, it must
1405 set up the virtual network interface.
1407 First, decide which IP addresses you want to have associated with these
1408 devices, and what network mask they must have.
1410 Tinc will open a virtual network device (@file{/dev/tun}, @file{/dev/tap0} or similar),
1411 which will also create a network interface called something like @samp{tun0}, @samp{tap0}.
1412 If you are using the Linux tun/tap driver, the network interface will by default have the same name as the @var{netname}.
1413 Under Windows you can change the name of the network interface from the Network Connections control panel.
1416 You can configure the network interface by putting ordinary ifconfig, route, and other commands
1417 to a script named @file{@value{sysconfdir}/tinc/@var{netname}/tinc-up}.
1418 When tinc starts, this script will be executed. When tinc exits, it will execute the script named
1419 @file{@value{sysconfdir}/tinc/@var{netname}/tinc-down}, but normally you don't need to create that script.
1421 An example @file{tinc-up} script:
1425 ifconfig $INTERFACE 192.168.1.1 netmask 255.255.0.0
1428 This script gives the interface an IP address and a netmask.
1429 The kernel will also automatically add a route to this interface, so normally you don't need
1430 to add route commands to the @file{tinc-up} script.
1431 The kernel will also bring the interface up after this command.
1433 The netmask is the mask of the @emph{entire} VPN network, not just your
1436 The exact syntax of the ifconfig and route commands differs from platform to platform.
1437 You can look up the commands for setting addresses and adding routes in @ref{Platform specific information},
1438 but it is best to consult the manpages of those utilities on your platform.
1441 @c ==================================================================
1442 @node Example configuration
1443 @section Example configuration
1447 Imagine the following situation. Branch A of our example `company' wants to connect
1448 three branch offices in B, C and D using the Internet. All four offices
1449 have a 24/7 connection to the Internet.
1451 A is going to serve as the center of the network. B and C will connect
1452 to A, and D will connect to C. Each office will be assigned their own IP
1456 A: net 10.1.0.0 mask 255.255.0.0 gateway 10.1.54.1 internet IP 1.2.3.4
1457 B: net 10.2.0.0 mask 255.255.0.0 gateway 10.2.1.12 internet IP 2.3.4.5
1458 C: net 10.3.0.0 mask 255.255.0.0 gateway 10.3.69.254 internet IP 3.4.5.6
1459 D: net 10.4.0.0 mask 255.255.0.0 gateway 10.4.3.32 internet IP 4.5.6.7
1462 Here, ``gateway'' is the VPN IP address of the machine that is running the
1463 tincd, and ``internet IP'' is the IP address of the firewall, which does not
1464 need to run tincd, but it must do a port forwarding of TCP and UDP on port
1465 655 (unless otherwise configured).
1467 In this example, it is assumed that eth0 is the interface that points to
1468 the inner (physical) LAN of the office, although this could also be the
1469 same as the interface that leads to the Internet. The configuration of
1470 the real interface is also shown as a comment, to give you an idea of
1471 how these example host is set up. All branches use the netname `company'
1472 for this particular VPN.
1474 @subsubheading For Branch A
1476 @emph{BranchA} would be configured like this:
1478 In @file{@value{sysconfdir}/tinc/company/tinc-up}:
1481 # Real interface of internal network:
1482 # ifconfig eth0 10.1.54.1 netmask 255.255.0.0
1484 ifconfig $INTERFACE 10.1.54.1 netmask 255.0.0.0
1487 and in @file{@value{sysconfdir}/tinc/company/tinc.conf}:
1494 On all hosts, @file{@value{sysconfdir}/tinc/company/hosts/BranchA} contains:
1497 Subnet = 10.1.0.0/16
1500 -----BEGIN RSA PUBLIC KEY-----
1502 -----END RSA PUBLIC KEY-----
1505 Note that the IP addresses of eth0 and tap0 are the same.
1506 This is quite possible, if you make sure that the netmasks of the interfaces are different.
1507 It is in fact recommended to give both real internal network interfaces and tap interfaces the same IP address,
1508 since that will make things a lot easier to remember and set up.
1511 @subsubheading For Branch B
1513 In @file{@value{sysconfdir}/tinc/company/tinc-up}:
1516 # Real interface of internal network:
1517 # ifconfig eth0 10.2.43.8 netmask 255.255.0.0
1519 ifconfig $INTERFACE 10.2.1.12 netmask 255.0.0.0
1522 and in @file{@value{sysconfdir}/tinc/company/tinc.conf}:
1529 Note here that the internal address (on eth0) doesn't have to be the
1530 same as on the tap0 device. Also, ConnectTo is given so that this node will
1531 always try to connect to BranchA.
1533 On all hosts, in @file{@value{sysconfdir}/tinc/company/hosts/BranchB}:
1536 Subnet = 10.2.0.0/16
1539 -----BEGIN RSA PUBLIC KEY-----
1541 -----END RSA PUBLIC KEY-----
1545 @subsubheading For Branch C
1547 In @file{@value{sysconfdir}/tinc/company/tinc-up}:
1550 # Real interface of internal network:
1551 # ifconfig eth0 10.3.69.254 netmask 255.255.0.0
1553 ifconfig $INTERFACE 10.3.69.254 netmask 255.0.0.0
1556 and in @file{@value{sysconfdir}/tinc/company/tinc.conf}:
1564 C already has another daemon that runs on port 655, so they have to
1565 reserve another port for tinc. It knows the portnumber it has to listen on
1566 from it's own host configuration file.
1568 On all hosts, in @file{@value{sysconfdir}/tinc/company/hosts/BranchC}:
1572 Subnet = 10.3.0.0/16
1575 -----BEGIN RSA PUBLIC KEY-----
1577 -----END RSA PUBLIC KEY-----
1581 @subsubheading For Branch D
1583 In @file{@value{sysconfdir}/tinc/company/tinc-up}:
1586 # Real interface of internal network:
1587 # ifconfig eth0 10.4.3.32 netmask 255.255.0.0
1589 ifconfig $INTERFACE 10.4.3.32 netmask 255.0.0.0
1592 and in @file{@value{sysconfdir}/tinc/company/tinc.conf}:
1597 Device = /dev/net/tun
1600 D will be connecting to C, which has a tincd running for this network on
1601 port 2000. It knows the port number from the host configuration file.
1602 Also note that since D uses the tun/tap driver, the network interface
1603 will not be called `tun' or `tap0' or something like that, but will
1604 have the same name as netname.
1606 On all hosts, in @file{@value{sysconfdir}/tinc/company/hosts/BranchD}:
1609 Subnet = 10.4.0.0/16
1612 -----BEGIN RSA PUBLIC KEY-----
1614 -----END RSA PUBLIC KEY-----
1617 @subsubheading Key files
1619 A, B, C and D all have generated a public/private keypair with the following command:
1625 The private key is stored in @file{@value{sysconfdir}/tinc/company/rsa_key.priv},
1626 the public key is put into the host configuration file in the @file{@value{sysconfdir}/tinc/company/hosts/} directory.
1627 During key generation, tinc automatically guesses the right filenames based on the -n option and
1628 the Name directive in the @file{tinc.conf} file (if it is available).
1630 @subsubheading Starting
1632 After each branch has finished configuration and they have distributed
1633 the host configuration files amongst them, they can start their tinc daemons.
1634 They don't necessarily have to wait for the other branches to have started
1635 their daemons, tinc will try connecting until they are available.
1638 @c ==================================================================
1640 @chapter Running tinc
1642 If everything else is done, you can start tinc by typing the following command:
1645 tincd -n @var{netname}
1649 Tinc will detach from the terminal and continue to run in the background like a good daemon.
1650 If there are any problems however you can try to increase the debug level
1651 and look in the syslog to find out what the problems are.
1657 * Solving problems::
1659 * Sending bug reports::
1663 @c ==================================================================
1664 @node Runtime options
1665 @section Runtime options
1667 Besides the settings in the configuration file, tinc also accepts some
1668 command line options.
1670 @cindex command line
1671 @cindex runtime options
1675 @item -c, --config=@var{path}
1676 Read configuration options from the directory @var{path}. The default is
1677 @file{@value{sysconfdir}/tinc/@var{netname}/}.
1679 @item -D, --no-detach
1680 Don't fork and detach.
1681 This will also disable the automatic restart mechanism for fatal errors.
1684 @item -d, --debug=@var{level}
1685 Set debug level to @var{level}. The higher the debug level, the more gets
1686 logged. Everything goes via syslog.
1688 @item -k, --kill[=@var{signal}]
1689 Attempt to kill a running tincd (optionally with the specified @var{signal} instead of SIGTERM) and exit.
1690 Use it in conjunction with the -n option to make sure you kill the right tinc daemon.
1691 Under native Windows the optional argument is ignored,
1692 the service will always be stopped and removed.
1694 @item -n, --net=@var{netname}
1695 Use configuration for net @var{netname}.
1696 This will let tinc read all configuration files from
1697 @file{@value{sysconfdir}/tinc/@var{netname}/}.
1698 Specifying . for @var{netname} is the same as not specifying any @var{netname}.
1699 @xref{Multiple networks}.
1701 @item -K, --generate-keys[=@var{bits}]
1702 Generate public/private keypair of @var{bits} length. If @var{bits} is not specified,
1703 2048 is the default. tinc will ask where you want to store the files,
1704 but will default to the configuration directory (you can use the -c or -n option
1705 in combination with -K). After that, tinc will quit.
1707 @item -o, --option=[@var{HOST}.]@var{KEY}=@var{VALUE}
1708 Without specifying a @var{HOST}, this will set server configuration variable @var{KEY} to @var{VALUE}.
1709 If specified as @var{HOST}.@var{KEY}=@var{VALUE},
1710 this will set the host configuration variable @var{KEY} of the host named @var{HOST} to @var{VALUE}.
1711 This option can be used more than once to specify multiple configuration variables.
1714 Lock tinc into main memory.
1715 This will prevent sensitive data like shared private keys to be written to the system swap files/partitions.
1717 @item --logfile[=@var{file}]
1718 Write log entries to a file instead of to the system logging facility.
1719 If @var{file} is omitted, the default is @file{@value{localstatedir}/log/tinc.@var{netname}.log}.
1721 @item --pidfile=@var{file}
1722 Write PID to @var{file} instead of @file{@value{localstatedir}/run/tinc.@var{netname}.pid}.
1724 @item --bypass-security
1725 Disables encryption and authentication.
1726 Only useful for debugging.
1729 Change process root directory to the directory where the config file is
1730 located (@file{@value{sysconfdir}/tinc/@var{netname}/} as determined by
1731 -n/--net option or as given by -c/--config option), for added security.
1732 The chroot is performed after all the initialization is done, after
1733 writing pid files and opening network sockets.
1735 Note that this option alone does not do any good without -U/--user, below.
1737 Note also that tinc can't run scripts anymore (such as tinc-down or host-up),
1738 unless it's setup to be runnable inside chroot environment.
1740 @item -U, --user=@var{user}
1741 Switch to the given @var{user} after initialization, at the same time as
1742 chroot is performed (see --chroot above). With this option tinc drops
1743 privileges, for added security.
1746 Display a short reminder of these runtime options and terminate.
1749 Output version information and exit.
1753 @c ==================================================================
1758 You can also send the following signals to a running tincd process:
1764 Forces tinc to try to connect to all uplinks immediately.
1765 Usually tinc attempts to do this itself,
1766 but increases the time it waits between the attempts each time it failed,
1767 and if tinc didn't succeed to connect to an uplink the first time after it started,
1768 it defaults to the maximum time of 15 minutes.
1771 Partially rereads configuration files.
1772 Connections to hosts whose host config file are removed are closed.
1773 New outgoing connections specified in @file{tinc.conf} will be made.
1774 If the --logfile option is used, this will also close and reopen the log file,
1775 useful when log rotation is used.
1778 Temporarily increases debug level to 5.
1779 Send this signal again to revert to the original level.
1782 Dumps the connection list to syslog.
1785 Dumps virtual network device statistics, all known nodes, edges and subnets to syslog.
1788 Purges all information remembered about unreachable nodes.
1792 @c ==================================================================
1794 @section Debug levels
1796 @cindex debug levels
1797 The tinc daemon can send a lot of messages to the syslog.
1798 The higher the debug level, the more messages it will log.
1799 Each level inherits all messages of the previous level:
1805 This will log a message indicating tinc has started along with a version number.
1806 It will also log any serious error.
1809 This will log all connections that are made with other tinc daemons.
1812 This will log status and error messages from scripts and other tinc daemons.
1815 This will log all requests that are exchanged with other tinc daemons. These include
1816 authentication, key exchange and connection list updates.
1819 This will log a copy of everything received on the meta socket.
1822 This will log all network traffic over the virtual private network.
1826 @c ==================================================================
1827 @node Solving problems
1828 @section Solving problems
1830 If tinc starts without problems, but if the VPN doesn't work, you will have to find the cause of the problem.
1831 The first thing to do is to start tinc with a high debug level in the foreground,
1832 so you can directly see everything tinc logs:
1835 tincd -n @var{netname} -d5 -D
1838 If tinc does not log any error messages, then you might want to check the following things:
1841 @item @file{tinc-up} script
1842 Does this script contain the right commands?
1843 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.
1846 Does the Subnet (or Subnets) in the host configuration file of this host match the portion of the VPN that belongs to this host?
1848 @item Firewalls and NATs
1849 Do you have a firewall or a NAT device (a masquerading firewall or perhaps an ADSL router that performs masquerading)?
1850 If so, check that it allows TCP and UDP traffic on port 655.
1851 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.
1852 You can add @samp{TCPOnly = yes} to your host config file to force tinc to only use a single TCP connection,
1853 this works through most firewalls and NATs. Since version 1.0.10, tinc will automatically fall back to TCP if direct communication via UDP is not possible.
1858 @c ==================================================================
1859 @node Error messages
1860 @section Error messages
1862 What follows is a list of the most common error messages you might find in the logs.
1863 Some of them will only be visible if the debug level is high enough.
1866 @item Could not open /dev/tap0: No such device
1869 @item You forgot to `modprobe netlink_dev' or `modprobe ethertap'.
1870 @item You forgot to compile `Netlink device emulation' in the kernel.
1873 @item Can't write to /dev/net/tun: No such device
1876 @item You forgot to `modprobe tun'.
1877 @item You forgot to compile `Universal TUN/TAP driver' in the kernel.
1878 @item The tun device is located somewhere else in @file{/dev/}.
1881 @item Network address and prefix length do not match!
1884 @item The Subnet field must contain a @emph{network} address, trailing bits should be 0.
1885 @item If you only want to use one IP address, set the netmask to /32.
1888 @item Error reading RSA key file `rsa_key.priv': No such file or directory
1891 @item You forgot to create a public/private keypair.
1892 @item Specify the complete pathname to the private key file with the @samp{PrivateKeyFile} option.
1895 @item Warning: insecure file permissions for RSA private key file `rsa_key.priv'!
1898 @item The private key file is readable by users other than root.
1899 Use chmod to correct the file permissions.
1902 @item Creating metasocket failed: Address family not supported
1905 @item By default tinc tries to create both IPv4 and IPv6 sockets.
1906 On some platforms this might not be implemented.
1907 If the logs show @samp{Ready} later on, then at least one metasocket was created,
1908 and you can ignore this message.
1909 You can add @samp{AddressFamily = ipv4} to @file{tinc.conf} to prevent this from happening.
1912 @item Cannot route packet: unknown IPv4 destination 1.2.3.4
1915 @item You try to send traffic to a host on the VPN for which no Subnet is known.
1916 @item If it is a broadcast address (ending in .255), it probably is a samba server or a Windows host sending broadcast packets.
1920 @item Cannot route packet: ARP request for unknown address 1.2.3.4
1923 @item You try to send traffic to a host on the VPN for which no Subnet is known.
1926 @item Packet with destination 1.2.3.4 is looping back to us!
1929 @item Something is not configured right. Packets are being sent out to the
1930 virtual network device, but according to the Subnet directives in your host configuration
1931 file, those packets should go to your own host. Most common mistake is that
1932 you have a Subnet line in your host configuration file with a prefix length which is
1933 just as large as the prefix of the virtual network interface. The latter should in almost all
1934 cases be larger. Rethink your configuration.
1935 Note that you will only see this message if you specified a debug
1936 level of 5 or higher!
1937 @item Chances are that a @samp{Subnet = ...} line in the host configuration file of this tinc daemon is wrong.
1938 Change it to a subnet that is accepted locally by another interface,
1939 or if that is not the case, try changing the prefix length into /32.
1942 @item Node foo (1.2.3.4) is not reachable
1945 @item Node foo does not have a connection anymore, its tinc daemon is not running or its connection to the Internet is broken.
1948 @item Received UDP packet from unknown source 1.2.3.4 (port 12345)
1951 @item If you see this only sporadically, it is harmless and caused by a node sending packets using an old key.
1954 @item Got bad/bogus/unauthorized REQUEST from foo (1.2.3.4 port 12345)
1957 @item Node foo does not have the right public/private keypair.
1958 Generate new keypairs and distribute them again.
1959 @item An attacker tries to gain access to your VPN.
1960 @item A network error caused corruption of metadata sent from foo.
1965 @c ==================================================================
1966 @node Sending bug reports
1967 @section Sending bug reports
1969 If you really can't find the cause of a problem, or if you suspect tinc is not working right,
1970 you can send us a bugreport, see @ref{Contact information}.
1971 Be sure to include the following information in your bugreport:
1974 @item A clear description of what you are trying to achieve and what the problem is.
1975 @item What platform (operating system, version, hardware architecture) and which version of tinc you use.
1976 @item If compiling tinc fails, a copy of @file{config.log} and the error messages you get.
1977 @item Otherwise, a copy of @file{tinc.conf}, @file{tinc-up} and all files in the @file{hosts/} directory.
1978 @item The output of the commands @samp{ifconfig -a} and @samp{route -n} (or @samp{netstat -rn} if that doesn't work).
1979 @item The output of any command that fails to work as it should (like ping or traceroute).
1982 @c ==================================================================
1983 @node Technical information
1984 @chapter Technical information
1989 * The meta-protocol::
1994 @c ==================================================================
1995 @node The connection
1996 @section The connection
1999 Tinc is a daemon that takes VPN data and transmit that to another host
2000 computer over the existing Internet infrastructure.
2004 * The meta-connection::
2008 @c ==================================================================
2009 @node The UDP tunnel
2010 @subsection The UDP tunnel
2012 @cindex virtual network device
2014 The data itself is read from a character device file, the so-called
2015 @emph{virtual network device}. This device is associated with a network
2016 interface. Any data sent to this interface can be read from the device,
2017 and any data written to the device gets sent from the interface.
2018 There are two possible types of virtual network devices:
2019 `tun' style, which are point-to-point devices which can only handle IPv4 and/or IPv6 packets,
2020 and `tap' style, which are Ethernet devices and handle complete Ethernet frames.
2022 So when tinc reads an Ethernet frame from the device, it determines its
2023 type. When tinc is in it's default routing mode, it can handle IPv4 and IPv6
2024 packets. Depending on the Subnet lines, it will send the packets off to their destination IP address.
2025 In the `switch' and `hub' mode, tinc will use broadcasts and MAC address discovery
2026 to deduce the destination of the packets.
2027 Since the latter modes only depend on the link layer information,
2028 any protocol that runs over Ethernet is supported (for instance IPX and Appletalk).
2029 However, only `tap' style devices provide this information.
2031 After the destination has been determined,
2032 the packet will be compressed (optionally),
2033 a sequence number will be added to the packet,
2034 the packet will then be encrypted
2035 and a message authentication code will be appended.
2037 @cindex encapsulating
2039 When that is done, time has come to actually transport the
2040 packet to the destination computer. We do this by sending the packet
2041 over an UDP connection to the destination host. This is called
2042 @emph{encapsulating}, the VPN packet (though now encrypted) is
2043 encapsulated in another IP datagram.
2045 When the destination receives this packet, the same thing happens, only
2046 in reverse. So it checks the message authentication code, decrypts the contents of the UDP datagram,
2047 checks the sequence number
2048 and writes the decrypted information to its own virtual network device.
2050 If the virtual network device is a `tun' device (a point-to-point tunnel),
2051 there is no problem for the kernel to accept a packet.
2052 However, if it is a `tap' device (this is the only available type on FreeBSD),
2053 the destination MAC address must match that of the virtual network interface.
2054 If tinc is in it's default routing mode, ARP does not work, so the correct destination MAC
2055 can not be known by the sending host.
2056 Tinc solves this by letting the receiving end detect the MAC address of its own virtual network interface
2057 and overwriting the destination MAC address of the received packet.
2059 In switch or hub modes ARP does work so the sender already knows the correct destination MAC address.
2060 In those modes every interface should have a unique MAC address, so make sure they are not the same.
2061 Because switch and hub modes rely on MAC addresses to function correctly,
2062 these modes cannot be used on the following operating systems which don't have a `tap' style virtual network device:
2063 OpenBSD, NetBSD, Darwin and Solaris.
2066 @c ==================================================================
2067 @node The meta-connection
2068 @subsection The meta-connection
2070 Having only a UDP connection available is not enough. Though suitable
2071 for transmitting data, we want to be able to reliably send other
2072 information, such as routing and session key information to somebody.
2075 TCP is a better alternative, because it already contains protection
2076 against information being lost, unlike UDP.
2078 So we establish two connections. One for the encrypted VPN data, and one
2079 for other information, the meta-data. Hence, we call the second
2080 connection the meta-connection. We can now be sure that the
2081 meta-information doesn't get lost on the way to another computer.
2083 @cindex data-protocol
2084 @cindex meta-protocol
2085 Like with any communication, we must have a protocol, so that everybody
2086 knows what everything stands for, and how she should react. Because we
2087 have two connections, we also have two protocols. The protocol used for
2088 the UDP data is the ``data-protocol,'' the other one is the
2091 The reason we don't use TCP for both protocols is that UDP is much
2092 better for encapsulation, even while it is less reliable. The real
2093 problem is that when TCP would be used to encapsulate a TCP stream
2094 that's on the private network, for every packet sent there would be
2095 three ACKs sent instead of just one. Furthermore, if there would be
2096 a timeout, both TCP streams would sense the timeout, and both would
2097 start re-sending packets.
2100 @c ==================================================================
2101 @node The meta-protocol
2102 @section The meta-protocol
2104 The meta protocol is used to tie all tinc daemons together, and
2105 exchange information about which tinc daemon serves which virtual
2108 The meta protocol consists of requests that can be sent to the other
2109 side. Each request has a unique number and several parameters. All
2110 requests are represented in the standard ASCII character set. It is
2111 possible to use tools such as telnet or netcat to connect to a tinc
2112 daemon started with the --bypass-security option
2113 and to read and write requests by hand, provided that one
2114 understands the numeric codes sent.
2116 The authentication scheme is described in @ref{Authentication protocol}. After a
2117 successful authentication, the server and the client will exchange all the
2118 information about other tinc daemons and subnets they know of, so that both
2119 sides (and all the other tinc daemons behind them) have their information
2126 ------------------------------------------------------------------
2127 ADD_EDGE node1 node2 21.32.43.54 655 222 0
2128 | | | | | +-> options
2129 | | | | +----> weight
2130 | | | +--------> UDP port of node2
2131 | | +----------------> real address of node2
2132 | +-------------------------> name of destination node
2133 +-------------------------------> name of source node
2135 ADD_SUBNET node 192.168.1.0/24
2136 | | +--> prefixlength
2137 | +--------> network address
2138 +------------------> owner of this subnet
2139 ------------------------------------------------------------------
2142 The ADD_EDGE messages are to inform other tinc daemons that a connection between
2143 two nodes exist. The address of the destination node is available so that
2144 VPN packets can be sent directly to that node.
2146 The ADD_SUBNET messages inform other tinc daemons that certain subnets belong
2147 to certain nodes. tinc will use it to determine to which node a VPN packet has
2154 ------------------------------------------------------------------
2155 DEL_EDGE node1 node2
2156 | +----> name of destination node
2157 +----------> name of source node
2159 DEL_SUBNET node 192.168.1.0/24
2160 | | +--> prefixlength
2161 | +--------> network address
2162 +------------------> owner of this subnet
2163 ------------------------------------------------------------------
2166 In case a connection between two daemons is closed or broken, DEL_EDGE messages
2167 are sent to inform the other daemons of that fact. Each daemon will calculate a
2168 new route to the the daemons, or mark them unreachable if there isn't any.
2175 ------------------------------------------------------------------
2176 REQ_KEY origin destination
2177 | +--> name of the tinc daemon it wants the key from
2178 +----------> name of the daemon that wants the key
2180 ANS_KEY origin destination 4ae0b0a82d6e0078 91 64 4
2181 | | \______________/ | | +--> MAC length
2182 | | | | +-----> digest algorithm
2183 | | | +--------> cipher algorithm
2184 | | +--> 128 bits key
2185 | +--> name of the daemon that wants the key
2186 +----------> name of the daemon that uses this key
2189 +--> daemon that has changed it's packet key
2190 ------------------------------------------------------------------
2193 The keys used to encrypt VPN packets are not sent out directly. This is
2194 because it would generate a lot of traffic on VPNs with many daemons, and
2195 chances are that not every tinc daemon will ever send a packet to every
2196 other daemon. Instead, if a daemon needs a key it sends a request for it
2197 via the meta connection of the nearest hop in the direction of the
2204 ------------------------------------------------------------------
2207 ------------------------------------------------------------------
2210 There is also a mechanism to check if hosts are still alive. Since network
2211 failures or a crash can cause a daemon to be killed without properly
2212 shutting down the TCP connection, this is necessary to keep an up to date
2213 connection list. PINGs are sent at regular intervals, except when there
2214 is also some other traffic. A little bit of salt (random data) is added
2215 with each PING and PONG message, to make sure that long sequences of PING/PONG
2216 messages without any other traffic won't result in known plaintext.
2218 This basically covers what is sent over the meta connection by tinc.
2221 @c ==================================================================
2227 Tinc got its name from ``TINC,'' short for @emph{There Is No Cabal}; the
2228 alleged Cabal was/is an organisation that was said to keep an eye on the
2229 entire Internet. As this is exactly what you @emph{don't} want, we named
2230 the tinc project after TINC.
2233 But in order to be ``immune'' to eavesdropping, you'll have to encrypt
2234 your data. Because tinc is a @emph{Secure} VPN (SVPN) daemon, it does
2235 exactly that: encrypt.
2236 Tinc by default uses blowfish encryption with 128 bit keys in CBC mode, 32 bit
2237 sequence numbers and 4 byte long message authentication codes to make sure
2238 eavesdroppers cannot get and cannot change any information at all from the
2239 packets they can intercept. The encryption algorithm and message authentication
2240 algorithm can be changed in the configuration. The length of the message
2241 authentication codes is also adjustable. The length of the key for the
2242 encryption algorithm is always the default length used by OpenSSL.
2245 * Authentication protocol::
2246 * Encryption of network packets::
2251 @c ==================================================================
2252 @node Authentication protocol
2253 @subsection Authentication protocol
2255 @cindex authentication
2256 A new scheme for authentication in tinc has been devised, which offers some
2257 improvements over the protocol used in 1.0pre2 and 1.0pre3. Explanation is
2267 --------------------------------------------------------------------------
2268 client <attempts connection>
2270 server <accepts connection>
2274 +-------> name of tinc daemon
2278 +-------> name of tinc daemon
2280 client META_KEY 5f0823a93e35b69e...7086ec7866ce582b
2281 \_________________________________/
2282 +-> RSAKEYLEN bits totally random string S1,
2283 encrypted with server's public RSA key
2285 server META_KEY 6ab9c1640388f8f0...45d1a07f8a672630
2286 \_________________________________/
2287 +-> RSAKEYLEN bits totally random string S2,
2288 encrypted with client's public RSA key
2291 - the client will symmetrically encrypt outgoing traffic using S1
2292 - the server will symmetrically encrypt outgoing traffic using S2
2294 client CHALLENGE da02add1817c1920989ba6ae2a49cecbda0
2295 \_________________________________/
2296 +-> CHALLEN bits totally random string H1
2298 server CHALLENGE 57fb4b2ccd70d6bb35a64c142f47e61d57f
2299 \_________________________________/
2300 +-> CHALLEN bits totally random string H2
2302 client CHAL_REPLY 816a86
2303 +-> 160 bits SHA1 of H2
2305 server CHAL_REPLY 928ffe
2306 +-> 160 bits SHA1 of H1
2308 After the correct challenge replies are received, both ends have proved
2309 their identity. Further information is exchanged.
2311 client ACK 655 123 0
2313 | +----> estimated weight
2314 +--------> listening port of client
2316 server ACK 655 321 0
2318 | +----> estimated weight
2319 +--------> listening port of server
2320 --------------------------------------------------------------------------
2323 This new scheme has several improvements, both in efficiency and security.
2325 First of all, the server sends exactly the same kind of messages over the wire
2326 as the client. The previous versions of tinc first authenticated the client,
2327 and then the server. This scheme even allows both sides to send their messages
2328 simultaneously, there is no need to wait for the other to send something first.
2329 This means that any calculations that need to be done upon sending or receiving
2330 a message can also be done in parallel. This is especially important when doing
2331 RSA encryption/decryption. Given that these calculations are the main part of
2332 the CPU time spent for the authentication, speed is improved by a factor 2.
2334 Second, only one RSA encrypted message is sent instead of two. This reduces the
2335 amount of information attackers can see (and thus use for a cryptographic
2336 attack). It also improves speed by a factor two, making the total speedup a
2339 Third, and most important:
2340 The symmetric cipher keys are exchanged first, the challenge is done
2341 afterwards. In the previous authentication scheme, because a man-in-the-middle
2342 could pass the challenge/chal_reply phase (by just copying the messages between
2343 the two real tinc daemons), but no information was exchanged that was really
2344 needed to read the rest of the messages, the challenge/chal_reply phase was of
2345 no real use. The man-in-the-middle was only stopped by the fact that only after
2346 the ACK messages were encrypted with the symmetric cipher. Potentially, it
2347 could even send it's own symmetric key to the server (if it knew the server's
2348 public key) and read some of the metadata the server would send it (it was
2349 impossible for the mitm to read actual network packets though). The new scheme
2350 however prevents this.
2352 This new scheme makes sure that first of all, symmetric keys are exchanged. The
2353 rest of the messages are then encrypted with the symmetric cipher. Then, each
2354 side can only read received messages if they have their private key. The
2355 challenge is there to let the other side know that the private key is really
2356 known, because a challenge reply can only be sent back if the challenge is
2357 decrypted correctly, and that can only be done with knowledge of the private
2360 Fourth: the first thing that is sent via the symmetric cipher encrypted
2361 connection is a totally random string, so that there is no known plaintext (for
2362 an attacker) in the beginning of the encrypted stream.
2365 @c ==================================================================
2366 @node Encryption of network packets
2367 @subsection Encryption of network packets
2370 A data packet can only be sent if the encryption key is known to both
2371 parties, and the connection is activated. If the encryption key is not
2372 known, a request is sent to the destination using the meta connection
2373 to retrieve it. The packet is stored in a queue while waiting for the
2377 The UDP packet containing the network packet from the VPN has the following layout:
2380 ... | IP header | UDP header | seqno | VPN packet | MAC | UDP trailer
2381 \___________________/\_____/
2383 V +---> digest algorithm
2384 Encrypted with symmetric cipher
2387 So, the entire VPN packet is encrypted using a symmetric cipher, including a 32 bits
2388 sequence number that is added in front of the actual VPN packet, to act as a unique
2389 IV for each packet and to prevent replay attacks. A message authentication code
2390 is added to the UDP packet to prevent alteration of packets. By default the
2391 first 4 bytes of the digest are used for this, but this can be changed using
2392 the MACLength configuration variable.
2394 @c ==================================================================
2395 @node Security issues
2396 @subsection Security issues
2398 In August 2000, we discovered the existence of a security hole in all versions
2399 of tinc up to and including 1.0pre2. This had to do with the way we exchanged
2400 keys. Since then, we have been working on a new authentication scheme to make
2401 tinc as secure as possible. The current version uses the OpenSSL library and
2402 uses strong authentication with RSA keys.
2404 On the 29th of December 2001, Jerome Etienne posted a security analysis of tinc
2405 1.0pre4. Due to a lack of sequence numbers and a message authentication code
2406 for each packet, an attacker could possibly disrupt certain network services or
2407 launch a denial of service attack by replaying intercepted packets. The current
2408 version adds sequence numbers and message authentication codes to prevent such
2411 On the 15th of September 2003, Peter Gutmann posted a security analysis of tinc
2412 1.0.1. He argues that the 32 bit sequence number used by tinc is not a good IV,
2413 that tinc's default length of 4 bytes for the MAC is too short, and he doesn't
2414 like tinc's use of RSA during authentication. We do not know of a security hole
2415 in this version of tinc, but tinc's security is not as strong as TLS or IPsec.
2416 We will address these issues in tinc 2.0.
2418 Cryptography is a hard thing to get right. We cannot make any
2419 guarantees. Time, review and feedback are the only things that can
2420 prove the security of any cryptographic product. If you wish to review
2421 tinc or give us feedback, you are stronly encouraged to do so.
2424 @c ==================================================================
2425 @node Platform specific information
2426 @chapter Platform specific information
2429 * Interface configuration::
2433 @c ==================================================================
2434 @node Interface configuration
2435 @section Interface configuration
2437 When configuring an interface, one normally assigns it an address and a
2438 netmask. The address uniquely identifies the host on the network attached to
2439 the interface. The netmask, combined with the address, forms a subnet. It is
2440 used to add a route to the routing table instructing the kernel to send all
2441 packets which fall into that subnet to that interface. Because all packets for
2442 the entire VPN should go to the virtual network interface used by tinc, the
2443 netmask should be such that it encompasses the entire VPN.
2447 @multitable {Darwin (MacOS/X)} {ifconfig route add -bla network address netmask netmask prefixlength interface}
2449 @tab @code{ifconfig} @var{interface} @var{address} @code{netmask} @var{netmask}
2450 @item Linux iproute2
2451 @tab @code{ip addr add} @var{address}@code{/}@var{prefixlength} @code{dev} @var{interface}
2453 @tab @code{ifconfig} @var{interface} @var{address} @code{netmask} @var{netmask}
2455 @tab @code{ifconfig} @var{interface} @var{address} @code{netmask} @var{netmask}
2457 @tab @code{ifconfig} @var{interface} @var{address} @code{netmask} @var{netmask}
2459 @tab @code{ifconfig} @var{interface} @var{address} @code{netmask} @var{netmask}
2460 @item Darwin (MacOS/X)
2461 @tab @code{ifconfig} @var{interface} @var{address} @code{netmask} @var{netmask}
2463 @tab @code{netsh interface ip set address} @var{interface} @code{static} @var{address} @var{netmask}
2468 @multitable {Darwin (MacOS/X)} {ifconfig route add -bla network address netmask netmask prefixlength interface}
2470 @tab @code{ifconfig} @var{interface} @code{add} @var{address}@code{/}@var{prefixlength}
2472 @tab @code{ifconfig} @var{interface} @code{inet6} @var{address} @code{prefixlen} @var{prefixlength}
2474 @tab @code{ifconfig} @var{interface} @code{inet6} @var{address} @code{prefixlen} @var{prefixlength}
2476 @tab @code{ifconfig} @var{interface} @code{inet6} @var{address} @code{prefixlen} @var{prefixlength}
2478 @tab @code{ifconfig} @var{interface} @code{inet6 plumb up}
2480 @tab @code{ifconfig} @var{interface} @code{inet6 addif} @var{address} @var{address}
2481 @item Darwin (MacOS/X)
2482 @tab @code{ifconfig} @var{interface} @code{inet6} @var{address} @code{prefixlen} @var{prefixlength}
2484 @tab @code{netsh interface ipv6 add address} @var{interface} @code{static} @var{address}/@var{prefixlength}
2487 On some platforms, when running tinc in switch mode, the VPN interface must be set to tap mode with an ifconfig command:
2489 @multitable {Darwin (MacOS/X)} {ifconfig route add -bla network address netmask netmask prefixlength interface}
2491 @tab @code{ifconfig} @var{interface} @code{link0}
2494 On Linux, it is possible to create a persistent tun/tap interface which will
2495 continue to exist even if tinc quit, although this is normally not required.
2496 It can be useful to set up a tun/tap interface owned by a non-root user, so
2497 tinc can be started without needing any root privileges at all.
2499 @multitable {Darwin (MacOS/X)} {ifconfig route add -bla network address netmask netmask prefixlength interface}
2501 @tab @code{ip tuntap add dev} @var{interface} @code{mode} @var{tun|tap} @code{user} @var{username}
2504 @c ==================================================================
2508 In some cases it might be necessary to add more routes to the virtual network
2509 interface. There are two ways to indicate which interface a packet should go
2510 to, one is to use the name of the interface itself, another way is to specify
2511 the (local) address that is assigned to that interface (@var{local_address}). The
2512 former way is unambiguous and therefore preferable, but not all platforms
2515 Adding routes to IPv4 subnets:
2517 @multitable {Darwin (MacOS/X)} {ifconfig route add -bla network address netmask netmask prefixlength interface}
2519 @tab @code{route add -net} @var{network_address} @code{netmask} @var{netmask} @var{interface}
2520 @item Linux iproute2
2521 @tab @code{ip route add} @var{network_address}@code{/}@var{prefixlength} @code{dev} @var{interface}
2523 @tab @code{route add} @var{network_address}@code{/}@var{prefixlength} @var{local_address}
2525 @tab @code{route add} @var{network_address}@code{/}@var{prefixlength} @var{local_address}
2527 @tab @code{route add} @var{network_address}@code{/}@var{prefixlength} @var{local_address}
2529 @tab @code{route add} @var{network_address}@code{/}@var{prefixlength} @var{local_address} @code{-interface}
2530 @item Darwin (MacOS/X)
2531 @tab @code{route add} @var{network_address}@code{/}@var{prefixlength} @var{local_address}
2533 @tab @code{netsh routing ip add persistentroute} @var{network_address} @var{netmask} @var{interface} @var{local_address}
2536 Adding routes to IPv6 subnets:
2538 @multitable {Darwin (MacOS/X)} {ifconfig route add -bla network address netmask netmask prefixlength interface}
2540 @tab @code{route add -A inet6} @var{network_address}@code{/}@var{prefixlength} @var{interface}
2541 @item Linux iproute2
2542 @tab @code{ip route add} @var{network_address}@code{/}@var{prefixlength} @code{dev} @var{interface}
2544 @tab @code{route add -inet6} @var{network_address}@code{/}@var{prefixlength} @var{local_address}
2546 @tab @code{route add -inet6} @var{network_address} @var{local_address} @code{-prefixlen} @var{prefixlength}
2548 @tab @code{route add -inet6} @var{network_address} @var{local_address} @code{-prefixlen} @var{prefixlength}
2550 @tab @code{route add -inet6} @var{network_address}@code{/}@var{prefixlength} @var{local_address} @code{-interface}
2551 @item Darwin (MacOS/X)
2554 @tab @code{netsh interface ipv6 add route} @var{network address}/@var{prefixlength} @var{interface}
2558 @c ==================================================================
2564 * Contact information::
2569 @c ==================================================================
2570 @node Contact information
2571 @section Contact information
2574 Tinc's website is at @url{http://www.tinc-vpn.org/},
2575 this server is located in the Netherlands.
2578 We have an IRC channel on the FreeNode and OFTC IRC networks. Connect to
2579 @uref{http://www.freenode.net/, irc.freenode.net}
2581 @uref{http://www.oftc.net/, irc.oftc.net}
2582 and join channel #tinc.
2585 @c ==================================================================
2590 @item Ivo Timmermans (zarq)
2591 @item Guus Sliepen (guus) (@email{guus@@tinc-vpn.org})
2594 We have received a lot of valuable input from users. With their help,
2595 tinc has become the flexible and robust tool that it is today. We have
2596 composed a list of contributions, in the file called @file{THANKS} in
2597 the source distribution.
2600 @c ==================================================================
2602 @unnumbered Concept Index
2604 @c ==================================================================
2608 @c ==================================================================