1 \input texinfo @c -*-texinfo-*-
8 @include tincinclude.texi
11 @dircategory Networking tools
13 * tinc: (tinc). The tinc Manual.
16 This is the info manual for @value{PACKAGE} version @value{VERSION}, a Virtual Private Network daemon.
18 Copyright @copyright{} 1998-2012 Ivo Timmermans,
19 Guus Sliepen <guus@@tinc-vpn.org> and
20 Wessel Dankers <wsl@@tinc-vpn.org>.
22 Permission is granted to make and distribute verbatim copies of this
23 manual provided the copyright notice and this permission notice are
24 preserved on all copies.
26 Permission is granted to copy and distribute modified versions of this
27 manual under the conditions for verbatim copying, provided that the
28 entire resulting derived work is distributed under the terms of a
29 permission notice identical to this one.
35 @subtitle Setting up a Virtual Private Network with tinc
36 @author Ivo Timmermans and Guus Sliepen
39 @vskip 0pt plus 1filll
40 This is the info manual for @value{PACKAGE} version @value{VERSION}, a Virtual Private Network daemon.
42 Copyright @copyright{} 1998-2012 Ivo Timmermans,
43 Guus Sliepen <guus@@tinc-vpn.org> and
44 Wessel Dankers <wsl@@tinc-vpn.org>.
46 Permission is granted to make and distribute verbatim copies of this
47 manual provided the copyright notice and this permission notice are
48 preserved on all copies.
50 Permission is granted to copy and distribute modified versions of this
51 manual under the conditions for verbatim copying, provided that the
52 entire resulting derived work is distributed under the terms of a
53 permission notice identical to this one.
58 @c ==================================================================
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 Using tap devices is recommended.
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.
278 @c ==================================================================
279 @node Configuration of NetBSD kernels
280 @subsection Configuration of NetBSD kernels
282 For NetBSD version 1.5.2 and higher,
283 the tun driver is included in the default kernel configuration.
285 Tunneling IPv6 may not work on NetBSD's tun device.
288 @c ==================================================================
289 @node Configuration of Solaris kernels
290 @subsection Configuration of Solaris kernels
292 For Solaris 8 (SunOS 5.8) and higher,
293 the tun driver may or may not be included in the default kernel configuration.
294 If it isn't, the source can be downloaded from @uref{http://vtun.sourceforge.net/tun/}.
295 For x86 and sparc64 architectures, precompiled versions can be found at @uref{http://www.monkey.org/~dugsong/fragroute/}.
296 If the @file{net/if_tun.h} header file is missing, install it from the source package.
299 @c ==================================================================
300 @node Configuration of Darwin (MacOS/X) kernels
301 @subsection Configuration of Darwin (MacOS/X) kernels
303 Tinc on Darwin relies on a tunnel driver for its data acquisition from the kernel.
304 Tinc supports either the driver from @uref{http://tuntaposx.sourceforge.net/},
305 which supports both tun and tap style devices,
306 and also the driver from from @uref{http://chrisp.de/en/projects/tunnel.html}.
307 The former driver is recommended.
308 The tunnel driver must be loaded before starting tinc with the following command:
315 @c ==================================================================
316 @node Configuration of Windows
317 @subsection Configuration of Windows
319 You will need to install the latest TAP-Win32 driver from OpenVPN.
320 You can download it from @uref{http://openvpn.sourceforge.net}.
321 Using the Network Connections control panel,
322 configure the TAP-Win32 network interface in the same way as you would do from the tinc-up script,
323 as explained in the rest of the documentation.
326 @c ==================================================================
332 Before you can configure or build tinc, you need to have the OpenSSL,
333 zlib and lzo libraries installed on your system. If you try to configure tinc without
334 having them installed, configure will give you an error message, and stop.
343 @c ==================================================================
348 For all cryptography-related functions, tinc uses the functions provided
349 by the OpenSSL library.
351 If this library is not installed, you wil get an error when configuring
352 tinc for build. Support for running tinc without having OpenSSL
353 installed @emph{may} be added in the future.
355 You can use your operating system's package manager to install this if
356 available. Make sure you install the development AND runtime versions
359 If you have to install OpenSSL manually, you can get the source code
360 from @url{http://www.openssl.org/}. Instructions on how to configure,
361 build and install this package are included within the package. Please
362 make sure you build development and runtime libraries (which is the
365 If you installed the OpenSSL libraries from source, it may be necessary
366 to let configure know where they are, by passing configure one of the
367 --with-openssl-* parameters.
370 --with-openssl=DIR OpenSSL library and headers prefix
371 --with-openssl-include=DIR OpenSSL headers directory
372 (Default is OPENSSL_DIR/include)
373 --with-openssl-lib=DIR OpenSSL library directory
374 (Default is OPENSSL_DIR/lib)
378 @subsubheading License
381 The complete source code of tinc is covered by the GNU GPL version 2.
382 Since the license under which OpenSSL is distributed is not directly
383 compatible with the terms of the GNU GPL
384 @uref{http://www.openssl.org/support/faq.html#LEGAL2}, we
385 include an exemption to the GPL (see also the file COPYING.README) to allow
386 everyone to create a statically or dynamically linked executable:
389 This program is released under the GPL with the additional exemption
390 that compiling, linking, and/or using OpenSSL is allowed. You may
391 provide binary packages linked to the OpenSSL libraries, provided that
392 all other requirements of the GPL are met.
395 Since the LZO library used by tinc is also covered by the GPL,
396 we also present the following exemption:
399 Hereby I grant a special exception to the tinc VPN project
400 (http://www.tinc-vpn.org/) to link the LZO library with the OpenSSL library
401 (http://www.openssl.org).
403 Markus F.X.J. Oberhumer
407 @c ==================================================================
412 For the optional compression of UDP packets, tinc uses the functions provided
415 If this library is not installed, you wil get an error when configuring
416 tinc for build. Support for running tinc without having zlib
417 installed @emph{may} be added in the future.
419 You can use your operating system's package manager to install this if
420 available. Make sure you install the development AND runtime versions
423 If you have to install zlib manually, you can get the source code
424 from @url{http://www.gzip.org/zlib/}. Instructions on how to configure,
425 build and install this package are included within the package. Please
426 make sure you build development and runtime libraries (which is the
430 @c ==================================================================
435 Another form of compression is offered using the lzo library.
437 If this library is not installed, you wil get an error when configuring
438 tinc for build. Support for running tinc without having lzo
439 installed @emph{may} be added in the future.
441 You can use your operating system's package manager to install this if
442 available. Make sure you install the development AND runtime versions
445 If you have to install lzo manually, you can get the source code
446 from @url{http://www.oberhumer.com/opensource/lzo/}. Instructions on how to configure,
447 build and install this package are included within the package. Please
448 make sure you build development and runtime libraries (which is the
461 @c ==================================================================
463 @chapter Installation
465 If you use Debian, you may want to install one of the
466 precompiled packages for your system. These packages are equipped with
467 system startup scripts and sample configurations.
469 If you cannot use one of the precompiled packages, or you want to compile tinc
470 for yourself, you can use the source. The source is distributed under
471 the GNU General Public License (GPL). Download the source from the
472 @uref{http://www.tinc-vpn.org/download, download page}, which has
473 the checksums of these files listed; you may wish to check these with
474 md5sum before continuing.
476 Tinc comes in a convenient autoconf/automake package, which you can just
477 treat the same as any other package. Which is just untar it, type
478 `./configure' and then `make'.
479 More detailed instructions are in the file @file{INSTALL}, which is
480 included in the source distribution.
483 * Building and installing tinc::
488 @c ==================================================================
489 @node Building and installing tinc
490 @section Building and installing tinc
492 Detailed instructions on configuring the source, building tinc and installing tinc
493 can be found in the file called @file{INSTALL}.
495 @cindex binary package
496 If you happen to have a binary package for tinc for your distribution,
497 you can use the package management tools of that distribution to install tinc.
498 The documentation that comes along with your distribution will tell you how to do that.
501 * Darwin (MacOS/X) build environment::
502 * Cygwin (Windows) build environment::
503 * MinGW (Windows) build environment::
507 @c ==================================================================
508 @node Darwin (MacOS/X) build environment
509 @subsection Darwin (MacOS/X) build environment
511 In order to build tinc on Darwin, you need to install the MacOS/X Developer Tools
512 from @uref{http://developer.apple.com/tools/macosxtools.html} and
513 a recent version of Fink from @uref{http://fink.sourceforge.net/}.
515 After installation use fink to download and install the following packages:
516 autoconf25, automake, dlcompat, m4, openssl, zlib and lzo.
518 @c ==================================================================
519 @node Cygwin (Windows) build environment
520 @subsection Cygwin (Windows) build environment
522 If Cygwin hasn't already been installed, install it directly from
523 @uref{http://www.cygwin.com/}.
525 When tinc is compiled in a Cygwin environment, it can only be run in this environment,
526 but all programs, including those started outside the Cygwin environment, will be able to use the VPN.
527 It will also support all features.
529 @c ==================================================================
530 @node MinGW (Windows) build environment
531 @subsection MinGW (Windows) build environment
533 You will need to install the MinGW environment from @uref{http://www.mingw.org}.
535 When tinc is compiled using MinGW it runs natively under Windows,
536 it is not necessary to keep MinGW installed.
538 When detaching, tinc will install itself as a service,
539 which will be restarted automatically after reboots.
542 @c ==================================================================
544 @section System files
546 Before you can run tinc, you must make sure you have all the needed
547 files on your system.
555 @c ==================================================================
557 @subsection Device files
560 Most operating systems nowadays come with the necessary device files by default,
561 or they have a mechanism to create them on demand.
563 If you use Linux and do not have udev installed,
564 you may need to create the following device file if it does not exist:
567 mknod -m 600 /dev/net/tun c 10 200
571 @c ==================================================================
573 @subsection Other files
575 @subsubheading @file{/etc/networks}
577 You may add a line to @file{/etc/networks} so that your VPN will get a
578 symbolic name. For example:
584 @subsubheading @file{/etc/services}
587 You may add this line to @file{/etc/services}. The effect is that you
588 may supply a @samp{tinc} as a valid port number to some programs. The
589 number 655 is registered with the IANA.
594 # Ivo Timmermans <ivo@@tinc-vpn.org>
609 @c ==================================================================
611 @chapter Configuration
614 * Configuration introduction::
615 * Multiple networks::
616 * How connections work::
617 * Configuration files::
618 * Generating keypairs::
619 * Network interfaces::
620 * Example configuration::
623 @c ==================================================================
624 @node Configuration introduction
625 @section Configuration introduction
627 Before actually starting to configure tinc and editing files,
628 make sure you have read this entire section so you know what to expect.
629 Then, make it clear to yourself how you want to organize your VPN:
630 What are the nodes (computers running tinc)?
631 What IP addresses/subnets do they have?
632 What is the network mask of the entire VPN?
633 Do you need special firewall rules?
634 Do you have to set up masquerading or forwarding rules?
635 Do you want to run tinc in router mode or switch mode?
636 These questions can only be answered by yourself,
637 you will not find the answers in this documentation.
638 Make sure you have an adequate understanding of networks in general.
639 @cindex Network Administrators Guide
640 A good resource on networking is the
641 @uref{http://www.linuxdoc.org/LDP/nag2/, Linux Network Administrators Guide}.
643 If you have everything clearly pictured in your mind,
644 proceed in the following order:
645 First, generate the configuration files (@file{tinc.conf}, your host configuration file, @file{tinc-up} and perhaps @file{tinc-down}).
646 Then generate the keypairs.
647 Finally, distribute the host configuration files.
648 These steps are described in the subsections below.
651 @c ==================================================================
652 @node Multiple networks
653 @section Multiple networks
655 @cindex multiple networks
657 In order to allow you to run more than one tinc daemon on one computer,
658 for instance if your computer is part of more than one VPN,
659 you can assign a @var{netname} to your VPN.
660 It is not required if you only run one tinc daemon,
661 it doesn't even have to be the same on all the sites of your VPN,
662 but it is recommended that you choose one anyway.
664 We will asume you use a netname throughout this document.
665 This means that you call tincd with the -n argument,
666 which will assign a netname to this daemon.
668 The effect of this is that the daemon will set its configuration
669 root to @file{@value{sysconfdir}/tinc/@var{netname}/}, where @var{netname} is your argument to the -n
670 option. You'll notice that it appears in syslog as @file{tinc.@var{netname}}.
672 However, it is not strictly necessary that you call tinc with the -n
673 option. In this case, the network name would just be empty, and it will
674 be used as such. tinc now looks for files in @file{@value{sysconfdir}/tinc/}, instead of
675 @file{@value{sysconfdir}/tinc/@var{netname}/}; the configuration file should be @file{@value{sysconfdir}/tinc/tinc.conf},
676 and the host configuration files are now expected to be in @file{@value{sysconfdir}/tinc/hosts/}.
678 But it is highly recommended that you use this feature of tinc, because
679 it will be so much clearer whom your daemon talks to. Hence, we will
680 assume that you use it.
683 @c ==================================================================
684 @node How connections work
685 @section How connections work
687 When tinc starts up, it parses the command-line options and then
688 reads in the configuration file tinc.conf.
689 If it sees one or more `ConnectTo' values pointing to other tinc daemons in that file,
690 it will try to connect to those other daemons.
691 Whether this succeeds or not and whether `ConnectTo' is specified or not,
692 tinc will listen for incoming connection from other deamons.
693 If you did specify a `ConnectTo' value and the other side is not responding,
694 tinc will keep retrying.
695 This means that once started, tinc will stay running until you tell it to stop,
696 and failures to connect to other tinc daemons will not stop your tinc daemon
697 for trying again later.
698 This means you don't have to intervene if there are temporary network problems.
702 There is no real distinction between a server and a client in tinc.
703 If you wish, you can view a tinc daemon without a `ConnectTo' value as a server,
704 and one which does specify such a value as a client.
705 It does not matter if two tinc daemons have a `ConnectTo' value pointing to each other however.
708 @c ==================================================================
709 @node Configuration files
710 @section Configuration files
712 The actual configuration of the daemon is done in the file
713 @file{@value{sysconfdir}/tinc/@var{netname}/tinc.conf} and at least one other file in the directory
714 @file{@value{sysconfdir}/tinc/@var{netname}/hosts/}.
716 These file consists of comments (lines started with a #) or assignments
723 The variable names are case insensitive, and any spaces, tabs, newlines
724 and carriage returns are ignored. Note: it is not required that you put
725 in the `=' sign, but doing so improves readability. If you leave it
726 out, remember to replace it with at least one space character.
728 The server configuration is complemented with host specific configuration (see
729 the next section). Although all host configuration options for the local node
730 listed in this document can also be put in
731 @file{@value{sysconfdir}/tinc/@var{netname}/tinc.conf}, it is recommended to
732 put host specific configuration options in the host configuration file, as this
733 makes it easy to exchange with other nodes.
735 In this section all valid variables are listed in alphabetical order.
736 The default value is given between parentheses,
737 other comments are between square brackets.
740 * Main configuration variables::
741 * Host configuration variables::
747 @c ==================================================================
748 @node Main configuration variables
749 @subsection Main configuration variables
752 @cindex AddressFamily
753 @item AddressFamily = <ipv4|ipv6|any> (any)
754 This option affects the address family of listening and outgoing sockets.
755 If any is selected, then depending on the operating system
756 both IPv4 and IPv6 or just IPv6 listening sockets will be created.
758 @cindex BindToAddress
759 @item BindToAddress = <@var{address}> [<@var{port}>] [experimental]
760 If your computer has more than one IPv4 or IPv6 address, tinc
761 will by default listen on all of them for incoming connections.
762 Multiple BindToAddress variables may be specified,
763 in which case listening sockets for each specified address are made.
765 If no @var{port} is specified, the socket will be bound to the port specified by the Port option,
766 or to port 655 if neither is given.
767 To only bind to a specific port but not to a specific address, use "*" for the @var{address}.
769 This option may not work on all platforms.
771 @cindex BindToInterface
772 @item BindToInterface = <@var{interface}> [experimental]
773 If you have more than one network interface in your computer, tinc will
774 by default listen on all of them for incoming connections. It is
775 possible to bind tinc to a single interface like eth0 or ppp0 with this
778 This option may not work on all platforms.
781 @item Broadcast = <no | mst | direct> (mst) [experimental]
782 This option selects the way broadcast packets are sent to other daemons.
783 @emph{NOTE: all nodes in a VPN must use the same Broadcast mode, otherwise routing loops can form.}
787 Broadcast packets are never sent to other nodes.
790 Broadcast packets are sent and forwarded via the VPN's Minimum Spanning Tree.
791 This ensures broadcast packets reach all nodes.
794 Broadcast packets are sent directly to all nodes that can be reached directly.
795 Broadcast packets received from other nodes are never forwarded.
796 If the IndirectData option is also set, broadcast packets will only be sent to nodes which we have a meta connection to.
800 @item ConnectTo = <@var{name}>
801 Specifies which other tinc daemon to connect to on startup.
802 Multiple ConnectTo variables may be specified,
803 in which case outgoing connections to each specified tinc daemon are made.
804 The names should be known to this tinc daemon
805 (i.e., there should be a host configuration file for the name on the ConnectTo line).
807 If you don't specify a host with ConnectTo,
808 tinc won't try to connect to other daemons at all,
809 and will instead just listen for incoming connections.
812 @item DecrementTTL = <yes | no> (no) [experimental]
813 When enabled, tinc will decrement the Time To Live field in IPv4 packets, or the Hop Limit field in IPv6 packets,
814 before forwarding a received packet to the virtual network device or to another node,
815 and will drop packets that have a TTL value of zero,
816 in which case it will send an ICMP Time Exceeded packet back.
818 Do not use this option if you use switch mode and want to use IPv6.
821 @item Device = <@var{device}> (@file{/dev/tap0}, @file{/dev/net/tun} or other depending on platform)
822 The virtual network device to use.
823 Tinc will automatically detect what kind of device it is.
824 Note that you can only use one device per daemon.
825 Under Windows, use @var{Interface} instead of @var{Device}.
826 Note that you can only use one device per daemon.
827 See also @ref{Device files}.
830 @item DeviceType = <@var{type}> (platform dependent)
831 The type of the virtual network device.
832 Tinc will normally automatically select the right type of tun/tap interface, and this option should not be used.
833 However, this option can be used to select one of the special interface types, if support for them is compiled in.
838 Use a dummy interface.
839 No packets are ever read or written to a virtual network device.
840 Useful for testing, or when setting up a node that only forwards packets for other nodes.
844 Open a raw socket, and bind it to a pre-existing
845 @var{Interface} (eth0 by default).
846 All packets are read from this interface.
847 Packets received for the local node are written to the raw socket.
848 However, at least on Linux, the operating system does not process IP packets destined for the local host.
852 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}.
853 Packets are read from and written to this multicast socket.
854 This can be used to connect to UML, QEMU or KVM instances listening on the same multicast address.
855 Do NOT connect multiple tinc daemons to the same multicast address, this will very likely cause routing loops.
856 Also note that this can cause decrypted VPN packets to be sent out on a real network if misconfigured.
859 @item uml (not compiled in by default)
860 Create a UNIX socket with the filename specified by
861 @var{Device}, or @file{@value{localstatedir}/run/@var{netname}.umlsocket}
863 Tinc will wait for a User Mode Linux instance to connect to this socket.
866 @item vde (not compiled in by default)
867 Uses the libvdeplug library to connect to a Virtual Distributed Ethernet switch,
868 using the UNIX socket specified by
869 @var{Device}, or @file{@value{localstatedir}/run/vde.ctl}
873 Also, in case tinc does not seem to correctly interpret packets received from the virtual network device,
874 it can be used to change the way packets are interpreted:
877 @item tun (BSD and Linux)
879 Depending on the platform, this can either be with or without an address family header (see below).
882 @item tunnohead (BSD)
883 Set type to tun without an address family header.
884 Tinc will expect packets read from the virtual network device to start with an IP header.
885 On some platforms IPv6 packets cannot be read from or written to the device in this mode.
888 @item tunifhead (BSD)
889 Set type to tun with an address family header.
890 Tinc will expect packets read from the virtual network device
891 to start with a four byte header containing the address family,
892 followed by an IP header.
893 This mode should support both IPv4 and IPv6 packets.
895 @item tap (BSD and Linux)
897 Tinc will expect packets read from the virtual network device
898 to start with an Ethernet header.
902 @item DirectOnly = <yes|no> (no) [experimental]
903 When this option is enabled, packets that cannot be sent directly to the destination node,
904 but which would have to be forwarded by an intermediate node, are dropped instead.
905 When combined with the IndirectData option,
906 packets for nodes for which we do not have a meta connection with are also dropped.
909 @item Forwarding = <off|internal|kernel> (internal) [experimental]
910 This option selects the way indirect packets are forwarded.
914 Incoming packets that are not meant for the local node,
915 but which should be forwarded to another node, are dropped.
918 Incoming packets that are meant for another node are forwarded by tinc internally.
920 This is the default mode, and unless you really know you need another forwarding mode, don't change it.
923 Incoming packets are always sent to the TUN/TAP device, even if the packets are not for the local node.
924 This is less efficient, but allows the kernel to apply its routing and firewall rules on them,
925 and can also help debugging.
928 @cindex GraphDumpFile
929 @item GraphDumpFile = <@var{filename}> [experimental]
930 If this option is present,
931 tinc will dump the current network graph to the file @var{filename}
932 every minute, unless there were no changes to the graph.
933 The file is in a format that can be read by graphviz tools.
934 If @var{filename} starts with a pipe symbol |,
935 then the rest of the filename is interpreted as a shell command
936 that is executed, the graph is then sent to stdin.
939 @item Hostnames = <yes|no> (no)
940 This option selects whether IP addresses (both real and on the VPN)
941 should be resolved. Since DNS lookups are blocking, it might affect
942 tinc's efficiency, even stopping the daemon for a few seconds everytime
943 it does a lookup if your DNS server is not responding.
945 This does not affect resolving hostnames to IP addresses from the
949 @item Interface = <@var{interface}>
950 Defines the name of the interface corresponding to the virtual network device.
951 Depending on the operating system and the type of device this may or may not actually set the name of the interface.
952 Under Windows, this variable is used to select which network interface will be used.
953 If you specified a Device, this variable is almost always already correctly set.
955 @cindex LocalDiscovery
956 @item LocalDiscovery = <yes | no> (no) [experimental]
957 When enabled, tinc will try to detect peers that are on the same local network.
958 This will allow direct communication using LAN addresses, even if both peers are behind a NAT
959 and they only ConnectTo a third node outside the NAT,
960 which normally would prevent the peers from learning each other's LAN address.
962 Currently, local discovery is implemented by sending broadcast packets to the LAN during path MTU discovery.
963 This feature may not work in all possible situations.
966 @item Mode = <router|switch|hub> (router)
967 This option selects the way packets are routed to other daemons.
973 variables in the host configuration files will be used to form a routing table.
974 Only unicast packets of routable protocols (IPv4 and IPv6) are supported in this mode.
976 This is the default mode, and unless you really know you need another mode, don't change it.
980 In this mode the MAC addresses of the packets on the VPN will be used to
981 dynamically create a routing table just like an Ethernet switch does.
982 Unicast, multicast and broadcast packets of every protocol that runs over Ethernet are supported in this mode
983 at the cost of frequent broadcast ARP requests and routing table updates.
985 This mode is primarily useful if you want to bridge Ethernet segments.
989 This mode is almost the same as the switch mode, but instead
990 every packet will be broadcast to the other daemons
991 while no routing table is managed.
995 @item KeyExpire = <@var{seconds}> (3600)
996 This option controls the time the encryption keys used to encrypt the data
997 are valid. It is common practice to change keys at regular intervals to
998 make it even harder for crackers, even though it is thought to be nearly
999 impossible to crack a single key.
1002 @item MACExpire = <@var{seconds}> (600)
1003 This option controls the amount of time MAC addresses are kept before they are removed.
1004 This only has effect when Mode is set to "switch".
1007 @item Name = <@var{name}> [required]
1008 This is a symbolic name for this connection.
1009 The name should consist only of alfanumeric and underscore characters (a-z, A-Z, 0-9 and _).
1011 If Name starts with a $, then the contents of the environment variable that follows will be used.
1012 In that case, invalid characters will be converted to underscores.
1013 If Name is $HOST, but no such environment variable exist,
1014 the hostname will be read using the gethostnname() system call.
1016 @cindex PingInterval
1017 @item PingInterval = <@var{seconds}> (60)
1018 The number of seconds of inactivity that tinc will wait before sending a
1019 probe to the other end.
1022 @item PingTimeout = <@var{seconds}> (5)
1023 The number of seconds to wait for a response to pings or to allow meta
1024 connections to block. If the other end doesn't respond within this time,
1025 the connection is terminated, and the others will be notified of this.
1027 @cindex PriorityInheritance
1028 @item PriorityInheritance = <yes|no> (no) [experimental]
1029 When this option is enabled the value of the TOS field of tunneled IPv4 packets
1030 will be inherited by the UDP packets that are sent out.
1033 @item PrivateKey = <@var{key}> [obsolete]
1034 This is the RSA private key for tinc. However, for safety reasons it is
1035 advised to store private keys of any kind in separate files. This prevents
1036 accidental eavesdropping if you are editting the configuration file.
1038 @cindex PrivateKeyFile
1039 @item PrivateKeyFile = <@var{path}> (@file{@value{sysconfdir}/tinc/@var{netname}/rsa_key.priv})
1040 This is the full path name of the RSA private key file that was
1041 generated by @samp{tincd --generate-keys}. It must be a full path, not a
1044 Note that there must be exactly one of PrivateKey
1046 specified in the configuration file.
1048 @cindex ProcessPriority
1049 @item ProcessPriority = <low|normal|high>
1050 When this option is used the priority of the tincd process will be adjusted.
1051 Increasing the priority may help to reduce latency and packet loss on the VPN.
1054 @item Proxy = <@var{type}> <@var{address}> <@var{port}> [<@var{username}>] [experimental]
1055 Use the proxy at the given @var{address} and @var{port} when making outgoing connections.
1056 The following proxy types are currently supported:
1061 Connects to the proxy using the SOCKS version 4 protocol.
1062 Optionally, a @var{username} can be supplied which will be passed on to the proxy server.
1066 Connects to the proxy and sends a HTTP CONNECT request.
1069 No authentication methods are currently supported.
1072 @cindex ReplayWindow
1073 @item ReplayWindow = <bytes> (16)
1074 This is the size of the replay tracking window for each remote node, in bytes.
1075 The window is a bitfield which tracks 1 packet per bit, so for example
1076 the default setting of 16 will track up to 128 packets in the window. In high
1077 bandwidth scenarios, setting this to a higher value can reduce packet loss from
1078 the interaction of replay tracking with underlying real packet loss and/or
1079 reordering. Setting this to zero will disable replay tracking completely and
1080 pass all traffic, but leaves tinc vulnerable to replay-based attacks on your
1084 @cindex StrictSubnets
1085 @item StrictSubnets <yes|no> (no) [experimental]
1086 When this option is enabled tinc will only use Subnet statements which are
1087 present in the host config files in the local
1088 @file{@value{sysconfdir}/tinc/@var{netname}/hosts/} directory.
1090 @cindex TunnelServer
1091 @item TunnelServer = <yes|no> (no) [experimental]
1092 When this option is enabled tinc will no longer forward information between other tinc daemons,
1093 and will only allow connections with nodes for which host config files are present in the local
1094 @file{@value{sysconfdir}/tinc/@var{netname}/hosts/} directory.
1095 Setting this options also implicitly sets StrictSubnets.
1098 @item UDPRcvBuf = <bytes> (OS default)
1099 Sets the socket receive buffer size for the UDP socket, in bytes.
1100 If unset, the default buffer size will be used by the operating system.
1103 @item UDPSndBuf = <bytes> Pq OS default
1104 Sets the socket send buffer size for the UDP socket, in bytes.
1105 If unset, the default buffer size will be used by the operating system.
1110 @c ==================================================================
1111 @node Host configuration variables
1112 @subsection Host configuration variables
1116 @item Address = <@var{IP address}|@var{hostname}> [<port>] [recommended]
1117 This variable is only required if you want to connect to this host. It
1118 must resolve to the external IP address where the host can be reached,
1119 not the one that is internal to the VPN.
1120 If no port is specified, the default Port is used.
1123 @item Cipher = <@var{cipher}> (blowfish)
1124 The symmetric cipher algorithm used to encrypt UDP packets.
1125 Any cipher supported by OpenSSL is recognized.
1126 Furthermore, specifying "none" will turn off packet encryption.
1127 It is best to use only those ciphers which support CBC mode.
1130 @item ClampMSS = <yes|no> (yes)
1131 This option specifies whether tinc should clamp the maximum segment size (MSS)
1132 of TCP packets to the path MTU. This helps in situations where ICMP
1133 Fragmentation Needed or Packet too Big messages are dropped by firewalls.
1136 @item Compression = <@var{level}> (0)
1137 This option sets the level of compression used for UDP packets.
1138 Possible values are 0 (off), 1 (fast zlib) and any integer up to 9 (best zlib),
1139 10 (fast lzo) and 11 (best lzo).
1142 @item Digest = <@var{digest}> (sha1)
1143 The digest algorithm used to authenticate UDP packets.
1144 Any digest supported by OpenSSL is recognized.
1145 Furthermore, specifying "none" will turn off packet authentication.
1147 @cindex IndirectData
1148 @item IndirectData = <yes|no> (no)
1149 This option specifies whether other tinc daemons besides the one you
1150 specified with ConnectTo can make a direct connection to you. This is
1151 especially useful if you are behind a firewall and it is impossible to
1152 make a connection from the outside to your tinc daemon. Otherwise, it
1153 is best to leave this option out or set it to no.
1156 @item MACLength = <@var{bytes}> (4)
1157 The length of the message authentication code used to authenticate UDP packets.
1158 Can be anything from 0
1159 up to the length of the digest produced by the digest algorithm.
1162 @item PMTU = <@var{mtu}> (1514)
1163 This option controls the initial path MTU to this node.
1165 @cindex PMTUDiscovery
1166 @item PMTUDiscovery = <yes|no> (yes)
1167 When this option is enabled, tinc will try to discover the path MTU to this node.
1168 After the path MTU has been discovered, it will be enforced on the VPN.
1171 @item Port = <@var{port}> (655)
1172 This is the port this tinc daemon listens on.
1173 You can use decimal portnumbers or symbolic names (as listed in @file{/etc/services}).
1176 @item PublicKey = <@var{key}> [obsolete]
1177 This is the RSA public key for this host.
1179 @cindex PublicKeyFile
1180 @item PublicKeyFile = <@var{path}> [obsolete]
1181 This is the full path name of the RSA public key file that was generated
1182 by @samp{tincd --generate-keys}. It must be a full path, not a relative
1186 From version 1.0pre4 on tinc will store the public key directly into the
1187 host configuration file in PEM format, the above two options then are not
1188 necessary. Either the PEM format is used, or exactly
1189 @strong{one of the above two options} must be specified
1190 in each host configuration file, if you want to be able to establish a
1191 connection with that host.
1194 @item Subnet = <@var{address}[/@var{prefixlength}[#@var{weight}]]>
1195 The subnet which this tinc daemon will serve.
1196 Tinc tries to look up which other daemon it should send a packet to by searching the appropiate subnet.
1197 If the packet matches a subnet,
1198 it will be sent to the daemon who has this subnet in his host configuration file.
1199 Multiple subnet lines can be specified for each daemon.
1201 Subnets can either be single MAC, IPv4 or IPv6 addresses,
1202 in which case a subnet consisting of only that single address is assumed,
1203 or they can be a IPv4 or IPv6 network address with a prefixlength.
1204 For example, IPv4 subnets must be in a form like 192.168.1.0/24,
1205 where 192.168.1.0 is the network address and 24 is the number of bits set in the netmask.
1206 Note that subnets like 192.168.1.1/24 are invalid!
1207 Read a networking HOWTO/FAQ/guide if you don't understand this.
1208 IPv6 subnets are notated like fec0:0:0:1::/64.
1209 MAC addresses are notated like 0:1a:2b:3c:4d:5e.
1211 @cindex CIDR notation
1212 Prefixlength is the number of bits set to 1 in the netmask part; for
1213 example: netmask 255.255.255.0 would become /24, 255.255.252.0 becomes
1214 /22. This conforms to standard CIDR notation as described in
1215 @uref{ftp://ftp.isi.edu/in-notes/rfc1519.txt, RFC1519}
1217 @cindex Subnet weight
1218 A Subnet can be given a weight to indicate its priority over identical Subnets
1219 owned by different nodes. The default weight is 10. Lower values indicate
1220 higher priority. Packets will be sent to the node with the highest priority,
1221 unless that node is not reachable, in which case the node with the next highest
1222 priority will be tried, and so on.
1225 @item TCPonly = <yes|no> (no) [deprecated]
1226 If this variable is set to yes, then the packets are tunnelled over a
1227 TCP connection instead of a UDP connection. This is especially useful
1228 for those who want to run a tinc daemon from behind a masquerading
1229 firewall, or if UDP packet routing is disabled somehow.
1230 Setting this options also implicitly sets IndirectData.
1232 Since version 1.0.10, tinc will automatically detect whether communication via
1233 UDP is possible or not.
1237 @c ==================================================================
1242 Apart from reading the server and host configuration files,
1243 tinc can also run scripts at certain moments.
1244 Under Windows (not Cygwin), the scripts should have the extension .bat.
1248 @item @value{sysconfdir}/tinc/@var{netname}/tinc-up
1249 This is the most important script.
1250 If it is present it will be executed right after the tinc daemon has been
1251 started and has connected to the virtual network device.
1252 It should be used to set up the corresponding network interface,
1253 but can also be used to start other things.
1254 Under Windows you can use the Network Connections control panel instead of creating this script.
1257 @item @value{sysconfdir}/tinc/@var{netname}/tinc-down
1258 This script is started right before the tinc daemon quits.
1260 @item @value{sysconfdir}/tinc/@var{netname}/hosts/@var{host}-up
1261 This script is started when the tinc daemon with name @var{host} becomes reachable.
1263 @item @value{sysconfdir}/tinc/@var{netname}/hosts/@var{host}-down
1264 This script is started when the tinc daemon with name @var{host} becomes unreachable.
1266 @item @value{sysconfdir}/tinc/@var{netname}/host-up
1267 This script is started when any host becomes reachable.
1269 @item @value{sysconfdir}/tinc/@var{netname}/host-down
1270 This script is started when any host becomes unreachable.
1272 @item @value{sysconfdir}/tinc/@var{netname}/subnet-up
1273 This script is started when a Subnet becomes reachable.
1274 The Subnet and the node it belongs to are passed in environment variables.
1276 @item @value{sysconfdir}/tinc/@var{netname}/subnet-down
1277 This script is started when a Subnet becomes unreachable.
1280 @cindex environment variables
1281 The scripts are started without command line arguments,
1282 but can make use of certain environment variables.
1283 Under UNIX like operating systems the names of environment variables must be preceded by a $ in scripts.
1284 Under Windows, in @file{.bat} files, they have to be put between % signs.
1289 If a netname was specified, this environment variable contains it.
1293 Contains the name of this tinc daemon.
1297 Contains the name of the virtual network device that tinc uses.
1301 Contains the name of the virtual network interface that tinc uses.
1302 This should be used for commands like ifconfig.
1306 When a host becomes (un)reachable, this is set to its name.
1307 If a subnet becomes (un)reachable, this is set to the owner of that subnet.
1309 @cindex REMOTEADDRESS
1311 When a host becomes (un)reachable, this is set to its real address.
1315 When a host becomes (un)reachable,
1316 this is set to the port number it uses for communication with other tinc daemons.
1320 When a subnet becomes (un)reachable, this is set to the subnet.
1324 When a subnet becomes (un)reachable, this is set to the subnet weight.
1329 @c ==================================================================
1330 @node How to configure
1331 @subsection How to configure
1333 @subsubheading Step 1. Creating the main configuration file
1335 The main configuration file will be called @file{@value{sysconfdir}/tinc/@var{netname}/tinc.conf}.
1336 Adapt the following example to create a basic configuration file:
1339 Name = @var{yourname}
1340 Device = @file{/dev/tap0}
1343 Then, if you know to which other tinc daemon(s) yours is going to connect,
1344 add `ConnectTo' values.
1346 @subsubheading Step 2. Creating your host configuration file
1348 If you added a line containing `Name = yourname' in the main configuarion file,
1349 you will need to create a host configuration file @file{@value{sysconfdir}/tinc/@var{netname}/hosts/yourname}.
1350 Adapt the following example to create a host configuration file:
1353 Address = your.real.hostname.org
1354 Subnet = 192.168.1.0/24
1357 You can also use an IP address instead of a hostname.
1358 The `Subnet' specifies the address range that is local for @emph{your part of the VPN only}.
1359 If you have multiple address ranges you can specify more than one `Subnet'.
1360 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).
1363 @c ==================================================================
1364 @node Generating keypairs
1365 @section Generating keypairs
1367 @cindex key generation
1368 Now that you have already created the main configuration file and your host configuration file,
1369 you can easily create a public/private keypair by entering the following command:
1372 tincd -n @var{netname} -K
1375 Tinc will generate a public and a private key and ask you where to put them.
1376 Just press enter to accept the defaults.
1379 @c ==================================================================
1380 @node Network interfaces
1381 @section Network interfaces
1383 Before tinc can start transmitting data over the tunnel, it must
1384 set up the virtual network interface.
1386 First, decide which IP addresses you want to have associated with these
1387 devices, and what network mask they must have.
1389 Tinc will open a virtual network device (@file{/dev/tun}, @file{/dev/tap0} or similar),
1390 which will also create a network interface called something like @samp{tun0}, @samp{tap0}.
1391 If you are using the Linux tun/tap driver, the network interface will by default have the same name as the @var{netname}.
1392 Under Windows you can change the name of the network interface from the Network Connections control panel.
1395 You can configure the network interface by putting ordinary ifconfig, route, and other commands
1396 to a script named @file{@value{sysconfdir}/tinc/@var{netname}/tinc-up}.
1397 When tinc starts, this script will be executed. When tinc exits, it will execute the script named
1398 @file{@value{sysconfdir}/tinc/@var{netname}/tinc-down}, but normally you don't need to create that script.
1400 An example @file{tinc-up} script:
1404 ifconfig $INTERFACE 192.168.1.1 netmask 255.255.0.0
1407 This script gives the interface an IP address and a netmask.
1408 The kernel will also automatically add a route to this interface, so normally you don't need
1409 to add route commands to the @file{tinc-up} script.
1410 The kernel will also bring the interface up after this command.
1412 The netmask is the mask of the @emph{entire} VPN network, not just your
1415 The exact syntax of the ifconfig and route commands differs from platform to platform.
1416 You can look up the commands for setting addresses and adding routes in @ref{Platform specific information},
1417 but it is best to consult the manpages of those utilities on your platform.
1420 @c ==================================================================
1421 @node Example configuration
1422 @section Example configuration
1426 Imagine the following situation. Branch A of our example `company' wants to connect
1427 three branch offices in B, C and D using the Internet. All four offices
1428 have a 24/7 connection to the Internet.
1430 A is going to serve as the center of the network. B and C will connect
1431 to A, and D will connect to C. Each office will be assigned their own IP
1435 A: net 10.1.0.0 mask 255.255.0.0 gateway 10.1.54.1 internet IP 1.2.3.4
1436 B: net 10.2.0.0 mask 255.255.0.0 gateway 10.2.1.12 internet IP 2.3.4.5
1437 C: net 10.3.0.0 mask 255.255.0.0 gateway 10.3.69.254 internet IP 3.4.5.6
1438 D: net 10.4.0.0 mask 255.255.0.0 gateway 10.4.3.32 internet IP 4.5.6.7
1441 Here, ``gateway'' is the VPN IP address of the machine that is running the
1442 tincd, and ``internet IP'' is the IP address of the firewall, which does not
1443 need to run tincd, but it must do a port forwarding of TCP and UDP on port
1444 655 (unless otherwise configured).
1446 In this example, it is assumed that eth0 is the interface that points to
1447 the inner (physical) LAN of the office, although this could also be the
1448 same as the interface that leads to the Internet. The configuration of
1449 the real interface is also shown as a comment, to give you an idea of
1450 how these example host is set up. All branches use the netname `company'
1451 for this particular VPN.
1453 @subsubheading For Branch A
1455 @emph{BranchA} would be configured like this:
1457 In @file{@value{sysconfdir}/tinc/company/tinc-up}:
1460 # Real interface of internal network:
1461 # ifconfig eth0 10.1.54.1 netmask 255.255.0.0
1463 ifconfig $INTERFACE 10.1.54.1 netmask 255.0.0.0
1466 and in @file{@value{sysconfdir}/tinc/company/tinc.conf}:
1473 On all hosts, @file{@value{sysconfdir}/tinc/company/hosts/BranchA} contains:
1476 Subnet = 10.1.0.0/16
1479 -----BEGIN RSA PUBLIC KEY-----
1481 -----END RSA PUBLIC KEY-----
1484 Note that the IP addresses of eth0 and tap0 are the same.
1485 This is quite possible, if you make sure that the netmasks of the interfaces are different.
1486 It is in fact recommended to give both real internal network interfaces and tap interfaces the same IP address,
1487 since that will make things a lot easier to remember and set up.
1490 @subsubheading For Branch B
1492 In @file{@value{sysconfdir}/tinc/company/tinc-up}:
1495 # Real interface of internal network:
1496 # ifconfig eth0 10.2.43.8 netmask 255.255.0.0
1498 ifconfig $INTERFACE 10.2.1.12 netmask 255.0.0.0
1501 and in @file{@value{sysconfdir}/tinc/company/tinc.conf}:
1508 Note here that the internal address (on eth0) doesn't have to be the
1509 same as on the tap0 device. Also, ConnectTo is given so that this node will
1510 always try to connect to BranchA.
1512 On all hosts, in @file{@value{sysconfdir}/tinc/company/hosts/BranchB}:
1515 Subnet = 10.2.0.0/16
1518 -----BEGIN RSA PUBLIC KEY-----
1520 -----END RSA PUBLIC KEY-----
1524 @subsubheading For Branch C
1526 In @file{@value{sysconfdir}/tinc/company/tinc-up}:
1529 # Real interface of internal network:
1530 # ifconfig eth0 10.3.69.254 netmask 255.255.0.0
1532 ifconfig $INTERFACE 10.3.69.254 netmask 255.0.0.0
1535 and in @file{@value{sysconfdir}/tinc/company/tinc.conf}:
1543 C already has another daemon that runs on port 655, so they have to
1544 reserve another port for tinc. It knows the portnumber it has to listen on
1545 from it's own host configuration file.
1547 On all hosts, in @file{@value{sysconfdir}/tinc/company/hosts/BranchC}:
1551 Subnet = 10.3.0.0/16
1554 -----BEGIN RSA PUBLIC KEY-----
1556 -----END RSA PUBLIC KEY-----
1560 @subsubheading For Branch D
1562 In @file{@value{sysconfdir}/tinc/company/tinc-up}:
1565 # Real interface of internal network:
1566 # ifconfig eth0 10.4.3.32 netmask 255.255.0.0
1568 ifconfig $INTERFACE 10.4.3.32 netmask 255.0.0.0
1571 and in @file{@value{sysconfdir}/tinc/company/tinc.conf}:
1576 Device = /dev/net/tun
1579 D will be connecting to C, which has a tincd running for this network on
1580 port 2000. It knows the port number from the host configuration file.
1581 Also note that since D uses the tun/tap driver, the network interface
1582 will not be called `tun' or `tap0' or something like that, but will
1583 have the same name as netname.
1585 On all hosts, in @file{@value{sysconfdir}/tinc/company/hosts/BranchD}:
1588 Subnet = 10.4.0.0/16
1591 -----BEGIN RSA PUBLIC KEY-----
1593 -----END RSA PUBLIC KEY-----
1596 @subsubheading Key files
1598 A, B, C and D all have generated a public/private keypair with the following command:
1604 The private key is stored in @file{@value{sysconfdir}/tinc/company/rsa_key.priv},
1605 the public key is put into the host configuration file in the @file{@value{sysconfdir}/tinc/company/hosts/} directory.
1606 During key generation, tinc automatically guesses the right filenames based on the -n option and
1607 the Name directive in the @file{tinc.conf} file (if it is available).
1609 @subsubheading Starting
1611 After each branch has finished configuration and they have distributed
1612 the host configuration files amongst them, they can start their tinc daemons.
1613 They don't necessarily have to wait for the other branches to have started
1614 their daemons, tinc will try connecting until they are available.
1617 @c ==================================================================
1619 @chapter Running tinc
1621 If everything else is done, you can start tinc by typing the following command:
1624 tincd -n @var{netname}
1628 Tinc will detach from the terminal and continue to run in the background like a good daemon.
1629 If there are any problems however you can try to increase the debug level
1630 and look in the syslog to find out what the problems are.
1636 * Solving problems::
1638 * Sending bug reports::
1642 @c ==================================================================
1643 @node Runtime options
1644 @section Runtime options
1646 Besides the settings in the configuration file, tinc also accepts some
1647 command line options.
1649 @cindex command line
1650 @cindex runtime options
1654 @item -c, --config=@var{path}
1655 Read configuration options from the directory @var{path}. The default is
1656 @file{@value{sysconfdir}/tinc/@var{netname}/}.
1658 @item -D, --no-detach
1659 Don't fork and detach.
1660 This will also disable the automatic restart mechanism for fatal errors.
1663 @item -d, --debug=@var{level}
1664 Set debug level to @var{level}. The higher the debug level, the more gets
1665 logged. Everything goes via syslog.
1667 @item -k, --kill[=@var{signal}]
1668 Attempt to kill a running tincd (optionally with the specified @var{signal} instead of SIGTERM) and exit.
1669 Use it in conjunction with the -n option to make sure you kill the right tinc daemon.
1670 Under native Windows the optional argument is ignored,
1671 the service will always be stopped and removed.
1673 @item -n, --net=@var{netname}
1674 Use configuration for net @var{netname}.
1675 This will let tinc read all configuration files from
1676 @file{@value{sysconfdir}/tinc/@var{netname}/}.
1677 Specifying . for @var{netname} is the same as not specifying any @var{netname}.
1678 @xref{Multiple networks}.
1680 @item -K, --generate-keys[=@var{bits}]
1681 Generate public/private keypair of @var{bits} length. If @var{bits} is not specified,
1682 2048 is the default. tinc will ask where you want to store the files,
1683 but will default to the configuration directory (you can use the -c or -n option
1684 in combination with -K). After that, tinc will quit.
1686 @item -o, --option=[@var{HOST}.]@var{KEY}=@var{VALUE}
1687 Without specifying a @var{HOST}, this will set server configuration variable @var{KEY} to @var{VALUE}.
1688 If specified as @var{HOST}.@var{KEY}=@var{VALUE},
1689 this will set the host configuration variable @var{KEY} of the host named @var{HOST} to @var{VALUE}.
1690 This option can be used more than once to specify multiple configuration variables.
1693 Lock tinc into main memory.
1694 This will prevent sensitive data like shared private keys to be written to the system swap files/partitions.
1696 @item --logfile[=@var{file}]
1697 Write log entries to a file instead of to the system logging facility.
1698 If @var{file} is omitted, the default is @file{@value{localstatedir}/log/tinc.@var{netname}.log}.
1700 @item --pidfile=@var{file}
1701 Write PID to @var{file} instead of @file{@value{localstatedir}/run/tinc.@var{netname}.pid}.
1703 @item --bypass-security
1704 Disables encryption and authentication.
1705 Only useful for debugging.
1708 Change process root directory to the directory where the config file is
1709 located (@file{@value{sysconfdir}/tinc/@var{netname}/} as determined by
1710 -n/--net option or as given by -c/--config option), for added security.
1711 The chroot is performed after all the initialization is done, after
1712 writing pid files and opening network sockets.
1714 Note that this option alone does not do any good without -U/--user, below.
1716 Note also that tinc can't run scripts anymore (such as tinc-down or host-up),
1717 unless it's setup to be runnable inside chroot environment.
1719 @item -U, --user=@var{user}
1720 Switch to the given @var{user} after initialization, at the same time as
1721 chroot is performed (see --chroot above). With this option tinc drops
1722 privileges, for added security.
1725 Display a short reminder of these runtime options and terminate.
1728 Output version information and exit.
1732 @c ==================================================================
1737 You can also send the following signals to a running tincd process:
1743 Forces tinc to try to connect to all uplinks immediately.
1744 Usually tinc attempts to do this itself,
1745 but increases the time it waits between the attempts each time it failed,
1746 and if tinc didn't succeed to connect to an uplink the first time after it started,
1747 it defaults to the maximum time of 15 minutes.
1750 Partially rereads configuration files.
1751 Connections to hosts whose host config file are removed are closed.
1752 New outgoing connections specified in @file{tinc.conf} will be made.
1753 If the --logfile option is used, this will also close and reopen the log file,
1754 useful when log rotation is used.
1757 Temporarily increases debug level to 5.
1758 Send this signal again to revert to the original level.
1761 Dumps the connection list to syslog.
1764 Dumps virtual network device statistics, all known nodes, edges and subnets to syslog.
1767 Purges all information remembered about unreachable nodes.
1771 @c ==================================================================
1773 @section Debug levels
1775 @cindex debug levels
1776 The tinc daemon can send a lot of messages to the syslog.
1777 The higher the debug level, the more messages it will log.
1778 Each level inherits all messages of the previous level:
1784 This will log a message indicating tinc has started along with a version number.
1785 It will also log any serious error.
1788 This will log all connections that are made with other tinc daemons.
1791 This will log status and error messages from scripts and other tinc daemons.
1794 This will log all requests that are exchanged with other tinc daemons. These include
1795 authentication, key exchange and connection list updates.
1798 This will log a copy of everything received on the meta socket.
1801 This will log all network traffic over the virtual private network.
1805 @c ==================================================================
1806 @node Solving problems
1807 @section Solving problems
1809 If tinc starts without problems, but if the VPN doesn't work, you will have to find the cause of the problem.
1810 The first thing to do is to start tinc with a high debug level in the foreground,
1811 so you can directly see everything tinc logs:
1814 tincd -n @var{netname} -d5 -D
1817 If tinc does not log any error messages, then you might want to check the following things:
1820 @item @file{tinc-up} script
1821 Does this script contain the right commands?
1822 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.
1825 Does the Subnet (or Subnets) in the host configuration file of this host match the portion of the VPN that belongs to this host?
1827 @item Firewalls and NATs
1828 Do you have a firewall or a NAT device (a masquerading firewall or perhaps an ADSL router that performs masquerading)?
1829 If so, check that it allows TCP and UDP traffic on port 655.
1830 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.
1831 You can add @samp{TCPOnly = yes} to your host config file to force tinc to only use a single TCP connection,
1832 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.
1837 @c ==================================================================
1838 @node Error messages
1839 @section Error messages
1841 What follows is a list of the most common error messages you might find in the logs.
1842 Some of them will only be visible if the debug level is high enough.
1845 @item Could not open /dev/tap0: No such device
1848 @item You forgot to `modprobe netlink_dev' or `modprobe ethertap'.
1849 @item You forgot to compile `Netlink device emulation' in the kernel.
1852 @item Can't write to /dev/net/tun: No such device
1855 @item You forgot to `modprobe tun'.
1856 @item You forgot to compile `Universal TUN/TAP driver' in the kernel.
1857 @item The tun device is located somewhere else in @file{/dev/}.
1860 @item Network address and prefix length do not match!
1863 @item The Subnet field must contain a @emph{network} address, trailing bits should be 0.
1864 @item If you only want to use one IP address, set the netmask to /32.
1867 @item Error reading RSA key file `rsa_key.priv': No such file or directory
1870 @item You forgot to create a public/private keypair.
1871 @item Specify the complete pathname to the private key file with the @samp{PrivateKeyFile} option.
1874 @item Warning: insecure file permissions for RSA private key file `rsa_key.priv'!
1877 @item The private key file is readable by users other than root.
1878 Use chmod to correct the file permissions.
1881 @item Creating metasocket failed: Address family not supported
1884 @item By default tinc tries to create both IPv4 and IPv6 sockets.
1885 On some platforms this might not be implemented.
1886 If the logs show @samp{Ready} later on, then at least one metasocket was created,
1887 and you can ignore this message.
1888 You can add @samp{AddressFamily = ipv4} to @file{tinc.conf} to prevent this from happening.
1891 @item Cannot route packet: unknown IPv4 destination 1.2.3.4
1894 @item You try to send traffic to a host on the VPN for which no Subnet is known.
1895 @item If it is a broadcast address (ending in .255), it probably is a samba server or a Windows host sending broadcast packets.
1899 @item Cannot route packet: ARP request for unknown address 1.2.3.4
1902 @item You try to send traffic to a host on the VPN for which no Subnet is known.
1905 @item Packet with destination 1.2.3.4 is looping back to us!
1908 @item Something is not configured right. Packets are being sent out to the
1909 virtual network device, but according to the Subnet directives in your host configuration
1910 file, those packets should go to your own host. Most common mistake is that
1911 you have a Subnet line in your host configuration file with a prefix length which is
1912 just as large as the prefix of the virtual network interface. The latter should in almost all
1913 cases be larger. Rethink your configuration.
1914 Note that you will only see this message if you specified a debug
1915 level of 5 or higher!
1916 @item Chances are that a @samp{Subnet = ...} line in the host configuration file of this tinc daemon is wrong.
1917 Change it to a subnet that is accepted locally by another interface,
1918 or if that is not the case, try changing the prefix length into /32.
1921 @item Node foo (1.2.3.4) is not reachable
1924 @item Node foo does not have a connection anymore, its tinc daemon is not running or its connection to the Internet is broken.
1927 @item Received UDP packet from unknown source 1.2.3.4 (port 12345)
1930 @item If you see this only sporadically, it is harmless and caused by a node sending packets using an old key.
1933 @item Got bad/bogus/unauthorized REQUEST from foo (1.2.3.4 port 12345)
1936 @item Node foo does not have the right public/private keypair.
1937 Generate new keypairs and distribute them again.
1938 @item An attacker tries to gain access to your VPN.
1939 @item A network error caused corruption of metadata sent from foo.
1944 @c ==================================================================
1945 @node Sending bug reports
1946 @section Sending bug reports
1948 If you really can't find the cause of a problem, or if you suspect tinc is not working right,
1949 you can send us a bugreport, see @ref{Contact information}.
1950 Be sure to include the following information in your bugreport:
1953 @item A clear description of what you are trying to achieve and what the problem is.
1954 @item What platform (operating system, version, hardware architecture) and which version of tinc you use.
1955 @item If compiling tinc fails, a copy of @file{config.log} and the error messages you get.
1956 @item Otherwise, a copy of @file{tinc.conf}, @file{tinc-up} and all files in the @file{hosts/} directory.
1957 @item The output of the commands @samp{ifconfig -a} and @samp{route -n} (or @samp{netstat -rn} if that doesn't work).
1958 @item The output of any command that fails to work as it should (like ping or traceroute).
1961 @c ==================================================================
1962 @node Technical information
1963 @chapter Technical information
1968 * The meta-protocol::
1973 @c ==================================================================
1974 @node The connection
1975 @section The connection
1978 Tinc is a daemon that takes VPN data and transmit that to another host
1979 computer over the existing Internet infrastructure.
1983 * The meta-connection::
1987 @c ==================================================================
1988 @node The UDP tunnel
1989 @subsection The UDP tunnel
1991 @cindex virtual network device
1993 The data itself is read from a character device file, the so-called
1994 @emph{virtual network device}. This device is associated with a network
1995 interface. Any data sent to this interface can be read from the device,
1996 and any data written to the device gets sent from the interface.
1997 There are two possible types of virtual network devices:
1998 `tun' style, which are point-to-point devices which can only handle IPv4 and/or IPv6 packets,
1999 and `tap' style, which are Ethernet devices and handle complete Ethernet frames.
2001 So when tinc reads an Ethernet frame from the device, it determines its
2002 type. When tinc is in it's default routing mode, it can handle IPv4 and IPv6
2003 packets. Depending on the Subnet lines, it will send the packets off to their destination IP address.
2004 In the `switch' and `hub' mode, tinc will use broadcasts and MAC address discovery
2005 to deduce the destination of the packets.
2006 Since the latter modes only depend on the link layer information,
2007 any protocol that runs over Ethernet is supported (for instance IPX and Appletalk).
2008 However, only `tap' style devices provide this information.
2010 After the destination has been determined,
2011 the packet will be compressed (optionally),
2012 a sequence number will be added to the packet,
2013 the packet will then be encrypted
2014 and a message authentication code will be appended.
2016 @cindex encapsulating
2018 When that is done, time has come to actually transport the
2019 packet to the destination computer. We do this by sending the packet
2020 over an UDP connection to the destination host. This is called
2021 @emph{encapsulating}, the VPN packet (though now encrypted) is
2022 encapsulated in another IP datagram.
2024 When the destination receives this packet, the same thing happens, only
2025 in reverse. So it checks the message authentication code, decrypts the contents of the UDP datagram,
2026 checks the sequence number
2027 and writes the decrypted information to its own virtual network device.
2029 If the virtual network device is a `tun' device (a point-to-point tunnel),
2030 there is no problem for the kernel to accept a packet.
2031 However, if it is a `tap' device (this is the only available type on FreeBSD),
2032 the destination MAC address must match that of the virtual network interface.
2033 If tinc is in it's default routing mode, ARP does not work, so the correct destination MAC
2034 can not be known by the sending host.
2035 Tinc solves this by letting the receiving end detect the MAC address of its own virtual network interface
2036 and overwriting the destination MAC address of the received packet.
2038 In switch or hub modes ARP does work so the sender already knows the correct destination MAC address.
2039 In those modes every interface should have a unique MAC address, so make sure they are not the same.
2040 Because switch and hub modes rely on MAC addresses to function correctly,
2041 these modes cannot be used on the following operating systems which don't have a `tap' style virtual network device:
2042 OpenBSD, NetBSD, Darwin and Solaris.
2045 @c ==================================================================
2046 @node The meta-connection
2047 @subsection The meta-connection
2049 Having only a UDP connection available is not enough. Though suitable
2050 for transmitting data, we want to be able to reliably send other
2051 information, such as routing and session key information to somebody.
2054 TCP is a better alternative, because it already contains protection
2055 against information being lost, unlike UDP.
2057 So we establish two connections. One for the encrypted VPN data, and one
2058 for other information, the meta-data. Hence, we call the second
2059 connection the meta-connection. We can now be sure that the
2060 meta-information doesn't get lost on the way to another computer.
2062 @cindex data-protocol
2063 @cindex meta-protocol
2064 Like with any communication, we must have a protocol, so that everybody
2065 knows what everything stands for, and how she should react. Because we
2066 have two connections, we also have two protocols. The protocol used for
2067 the UDP data is the ``data-protocol,'' the other one is the
2070 The reason we don't use TCP for both protocols is that UDP is much
2071 better for encapsulation, even while it is less reliable. The real
2072 problem is that when TCP would be used to encapsulate a TCP stream
2073 that's on the private network, for every packet sent there would be
2074 three ACKs sent instead of just one. Furthermore, if there would be
2075 a timeout, both TCP streams would sense the timeout, and both would
2076 start re-sending packets.
2079 @c ==================================================================
2080 @node The meta-protocol
2081 @section The meta-protocol
2083 The meta protocol is used to tie all tinc daemons together, and
2084 exchange information about which tinc daemon serves which virtual
2087 The meta protocol consists of requests that can be sent to the other
2088 side. Each request has a unique number and several parameters. All
2089 requests are represented in the standard ASCII character set. It is
2090 possible to use tools such as telnet or netcat to connect to a tinc
2091 daemon started with the --bypass-security option
2092 and to read and write requests by hand, provided that one
2093 understands the numeric codes sent.
2095 The authentication scheme is described in @ref{Authentication protocol}. After a
2096 successful authentication, the server and the client will exchange all the
2097 information about other tinc daemons and subnets they know of, so that both
2098 sides (and all the other tinc daemons behind them) have their information
2105 ------------------------------------------------------------------
2106 ADD_EDGE node1 node2 21.32.43.54 655 222 0
2107 | | | | | +-> options
2108 | | | | +----> weight
2109 | | | +--------> UDP port of node2
2110 | | +----------------> real address of node2
2111 | +-------------------------> name of destination node
2112 +-------------------------------> name of source node
2114 ADD_SUBNET node 192.168.1.0/24
2115 | | +--> prefixlength
2116 | +--------> network address
2117 +------------------> owner of this subnet
2118 ------------------------------------------------------------------
2121 The ADD_EDGE messages are to inform other tinc daemons that a connection between
2122 two nodes exist. The address of the destination node is available so that
2123 VPN packets can be sent directly to that node.
2125 The ADD_SUBNET messages inform other tinc daemons that certain subnets belong
2126 to certain nodes. tinc will use it to determine to which node a VPN packet has
2133 ------------------------------------------------------------------
2134 DEL_EDGE node1 node2
2135 | +----> name of destination node
2136 +----------> name of source node
2138 DEL_SUBNET node 192.168.1.0/24
2139 | | +--> prefixlength
2140 | +--------> network address
2141 +------------------> owner of this subnet
2142 ------------------------------------------------------------------
2145 In case a connection between two daemons is closed or broken, DEL_EDGE messages
2146 are sent to inform the other daemons of that fact. Each daemon will calculate a
2147 new route to the the daemons, or mark them unreachable if there isn't any.
2154 ------------------------------------------------------------------
2155 REQ_KEY origin destination
2156 | +--> name of the tinc daemon it wants the key from
2157 +----------> name of the daemon that wants the key
2159 ANS_KEY origin destination 4ae0b0a82d6e0078 91 64 4
2160 | | \______________/ | | +--> MAC length
2161 | | | | +-----> digest algorithm
2162 | | | +--------> cipher algorithm
2163 | | +--> 128 bits key
2164 | +--> name of the daemon that wants the key
2165 +----------> name of the daemon that uses this key
2168 +--> daemon that has changed it's packet key
2169 ------------------------------------------------------------------
2172 The keys used to encrypt VPN packets are not sent out directly. This is
2173 because it would generate a lot of traffic on VPNs with many daemons, and
2174 chances are that not every tinc daemon will ever send a packet to every
2175 other daemon. Instead, if a daemon needs a key it sends a request for it
2176 via the meta connection of the nearest hop in the direction of the
2183 ------------------------------------------------------------------
2186 ------------------------------------------------------------------
2189 There is also a mechanism to check if hosts are still alive. Since network
2190 failures or a crash can cause a daemon to be killed without properly
2191 shutting down the TCP connection, this is necessary to keep an up to date
2192 connection list. PINGs are sent at regular intervals, except when there
2193 is also some other traffic. A little bit of salt (random data) is added
2194 with each PING and PONG message, to make sure that long sequences of PING/PONG
2195 messages without any other traffic won't result in known plaintext.
2197 This basically covers what is sent over the meta connection by tinc.
2200 @c ==================================================================
2206 Tinc got its name from ``TINC,'' short for @emph{There Is No Cabal}; the
2207 alleged Cabal was/is an organisation that was said to keep an eye on the
2208 entire Internet. As this is exactly what you @emph{don't} want, we named
2209 the tinc project after TINC.
2212 But in order to be ``immune'' to eavesdropping, you'll have to encrypt
2213 your data. Because tinc is a @emph{Secure} VPN (SVPN) daemon, it does
2214 exactly that: encrypt.
2215 Tinc by default uses blowfish encryption with 128 bit keys in CBC mode, 32 bit
2216 sequence numbers and 4 byte long message authentication codes to make sure
2217 eavesdroppers cannot get and cannot change any information at all from the
2218 packets they can intercept. The encryption algorithm and message authentication
2219 algorithm can be changed in the configuration. The length of the message
2220 authentication codes is also adjustable. The length of the key for the
2221 encryption algorithm is always the default length used by OpenSSL.
2224 * Authentication protocol::
2225 * Encryption of network packets::
2230 @c ==================================================================
2231 @node Authentication protocol
2232 @subsection Authentication protocol
2234 @cindex authentication
2235 A new scheme for authentication in tinc has been devised, which offers some
2236 improvements over the protocol used in 1.0pre2 and 1.0pre3. Explanation is
2246 --------------------------------------------------------------------------
2247 client <attempts connection>
2249 server <accepts connection>
2253 +-------> name of tinc daemon
2257 +-------> name of tinc daemon
2259 client META_KEY 5f0823a93e35b69e...7086ec7866ce582b
2260 \_________________________________/
2261 +-> RSAKEYLEN bits totally random string S1,
2262 encrypted with server's public RSA key
2264 server META_KEY 6ab9c1640388f8f0...45d1a07f8a672630
2265 \_________________________________/
2266 +-> RSAKEYLEN bits totally random string S2,
2267 encrypted with client's public RSA key
2270 - the client will symmetrically encrypt outgoing traffic using S1
2271 - the server will symmetrically encrypt outgoing traffic using S2
2273 client CHALLENGE da02add1817c1920989ba6ae2a49cecbda0
2274 \_________________________________/
2275 +-> CHALLEN bits totally random string H1
2277 server CHALLENGE 57fb4b2ccd70d6bb35a64c142f47e61d57f
2278 \_________________________________/
2279 +-> CHALLEN bits totally random string H2
2281 client CHAL_REPLY 816a86
2282 +-> 160 bits SHA1 of H2
2284 server CHAL_REPLY 928ffe
2285 +-> 160 bits SHA1 of H1
2287 After the correct challenge replies are received, both ends have proved
2288 their identity. Further information is exchanged.
2290 client ACK 655 123 0
2292 | +----> estimated weight
2293 +--------> listening port of client
2295 server ACK 655 321 0
2297 | +----> estimated weight
2298 +--------> listening port of server
2299 --------------------------------------------------------------------------
2302 This new scheme has several improvements, both in efficiency and security.
2304 First of all, the server sends exactly the same kind of messages over the wire
2305 as the client. The previous versions of tinc first authenticated the client,
2306 and then the server. This scheme even allows both sides to send their messages
2307 simultaneously, there is no need to wait for the other to send something first.
2308 This means that any calculations that need to be done upon sending or receiving
2309 a message can also be done in parallel. This is especially important when doing
2310 RSA encryption/decryption. Given that these calculations are the main part of
2311 the CPU time spent for the authentication, speed is improved by a factor 2.
2313 Second, only one RSA encrypted message is sent instead of two. This reduces the
2314 amount of information attackers can see (and thus use for a cryptographic
2315 attack). It also improves speed by a factor two, making the total speedup a
2318 Third, and most important:
2319 The symmetric cipher keys are exchanged first, the challenge is done
2320 afterwards. In the previous authentication scheme, because a man-in-the-middle
2321 could pass the challenge/chal_reply phase (by just copying the messages between
2322 the two real tinc daemons), but no information was exchanged that was really
2323 needed to read the rest of the messages, the challenge/chal_reply phase was of
2324 no real use. The man-in-the-middle was only stopped by the fact that only after
2325 the ACK messages were encrypted with the symmetric cipher. Potentially, it
2326 could even send it's own symmetric key to the server (if it knew the server's
2327 public key) and read some of the metadata the server would send it (it was
2328 impossible for the mitm to read actual network packets though). The new scheme
2329 however prevents this.
2331 This new scheme makes sure that first of all, symmetric keys are exchanged. The
2332 rest of the messages are then encrypted with the symmetric cipher. Then, each
2333 side can only read received messages if they have their private key. The
2334 challenge is there to let the other side know that the private key is really
2335 known, because a challenge reply can only be sent back if the challenge is
2336 decrypted correctly, and that can only be done with knowledge of the private
2339 Fourth: the first thing that is sent via the symmetric cipher encrypted
2340 connection is a totally random string, so that there is no known plaintext (for
2341 an attacker) in the beginning of the encrypted stream.
2344 @c ==================================================================
2345 @node Encryption of network packets
2346 @subsection Encryption of network packets
2349 A data packet can only be sent if the encryption key is known to both
2350 parties, and the connection is activated. If the encryption key is not
2351 known, a request is sent to the destination using the meta connection
2352 to retrieve it. The packet is stored in a queue while waiting for the
2356 The UDP packet containing the network packet from the VPN has the following layout:
2359 ... | IP header | UDP header | seqno | VPN packet | MAC | UDP trailer
2360 \___________________/\_____/
2362 V +---> digest algorithm
2363 Encrypted with symmetric cipher
2366 So, the entire VPN packet is encrypted using a symmetric cipher, including a 32 bits
2367 sequence number that is added in front of the actual VPN packet, to act as a unique
2368 IV for each packet and to prevent replay attacks. A message authentication code
2369 is added to the UDP packet to prevent alteration of packets. By default the
2370 first 4 bytes of the digest are used for this, but this can be changed using
2371 the MACLength configuration variable.
2373 @c ==================================================================
2374 @node Security issues
2375 @subsection Security issues
2377 In August 2000, we discovered the existence of a security hole in all versions
2378 of tinc up to and including 1.0pre2. This had to do with the way we exchanged
2379 keys. Since then, we have been working on a new authentication scheme to make
2380 tinc as secure as possible. The current version uses the OpenSSL library and
2381 uses strong authentication with RSA keys.
2383 On the 29th of December 2001, Jerome Etienne posted a security analysis of tinc
2384 1.0pre4. Due to a lack of sequence numbers and a message authentication code
2385 for each packet, an attacker could possibly disrupt certain network services or
2386 launch a denial of service attack by replaying intercepted packets. The current
2387 version adds sequence numbers and message authentication codes to prevent such
2390 On the 15th of September 2003, Peter Gutmann posted a security analysis of tinc
2391 1.0.1. He argues that the 32 bit sequence number used by tinc is not a good IV,
2392 that tinc's default length of 4 bytes for the MAC is too short, and he doesn't
2393 like tinc's use of RSA during authentication. We do not know of a security hole
2394 in this version of tinc, but tinc's security is not as strong as TLS or IPsec.
2395 We will address these issues in tinc 2.0.
2397 Cryptography is a hard thing to get right. We cannot make any
2398 guarantees. Time, review and feedback are the only things that can
2399 prove the security of any cryptographic product. If you wish to review
2400 tinc or give us feedback, you are stronly encouraged to do so.
2403 @c ==================================================================
2404 @node Platform specific information
2405 @chapter Platform specific information
2408 * Interface configuration::
2412 @c ==================================================================
2413 @node Interface configuration
2414 @section Interface configuration
2416 When configuring an interface, one normally assigns it an address and a
2417 netmask. The address uniquely identifies the host on the network attached to
2418 the interface. The netmask, combined with the address, forms a subnet. It is
2419 used to add a route to the routing table instructing the kernel to send all
2420 packets which fall into that subnet to that interface. Because all packets for
2421 the entire VPN should go to the virtual network interface used by tinc, the
2422 netmask should be such that it encompasses the entire VPN.
2426 @multitable {Darwin (MacOS/X)} {ifconfig route add -bla network address netmask netmask prefixlength interface}
2428 @tab @code{ifconfig} @var{interface} @var{address} @code{netmask} @var{netmask}
2429 @item Linux iproute2
2430 @tab @code{ip addr add} @var{address}@code{/}@var{prefixlength} @code{dev} @var{interface}
2432 @tab @code{ifconfig} @var{interface} @var{address} @code{netmask} @var{netmask}
2434 @tab @code{ifconfig} @var{interface} @var{address} @code{netmask} @var{netmask}
2436 @tab @code{ifconfig} @var{interface} @var{address} @code{netmask} @var{netmask}
2438 @tab @code{ifconfig} @var{interface} @var{address} @code{netmask} @var{netmask}
2439 @item Darwin (MacOS/X)
2440 @tab @code{ifconfig} @var{interface} @var{address} @code{netmask} @var{netmask}
2442 @tab @code{netsh interface ip set address} @var{interface} @code{static} @var{address} @var{netmask}
2447 @multitable {Darwin (MacOS/X)} {ifconfig route add -bla network address netmask netmask prefixlength interface}
2449 @tab @code{ifconfig} @var{interface} @code{add} @var{address}@code{/}@var{prefixlength}
2451 @tab @code{ifconfig} @var{interface} @code{inet6} @var{address} @code{prefixlen} @var{prefixlength}
2453 @tab @code{ifconfig} @var{interface} @code{inet6} @var{address} @code{prefixlen} @var{prefixlength}
2455 @tab @code{ifconfig} @var{interface} @code{inet6} @var{address} @code{prefixlen} @var{prefixlength}
2457 @tab @code{ifconfig} @var{interface} @code{inet6 plumb up}
2459 @tab @code{ifconfig} @var{interface} @code{inet6 addif} @var{address} @var{address}
2460 @item Darwin (MacOS/X)
2461 @tab @code{ifconfig} @var{interface} @code{inet6} @var{address} @code{prefixlen} @var{prefixlength}
2463 @tab @code{netsh interface ipv6 add address} @var{interface} @code{static} @var{address}/@var{prefixlength}
2466 On some platforms, when running tinc in switch mode, the VPN interface must be set to tap mode with an ifconfig command:
2468 @multitable {Darwin (MacOS/X)} {ifconfig route add -bla network address netmask netmask prefixlength interface}
2470 @tab @code{ifconfig} @var{interface} @code{link0}
2473 On Linux, it is possible to create a persistent tun/tap interface which will
2474 continue to exist even if tinc quit, although this is normally not required.
2475 It can be useful to set up a tun/tap interface owned by a non-root user, so
2476 tinc can be started without needing any root privileges at all.
2478 @multitable {Darwin (MacOS/X)} {ifconfig route add -bla network address netmask netmask prefixlength interface}
2480 @tab @code{ip tuntap add dev} @var{interface} @code{mode} @var{tun|tap} @code{user} @var{username}
2483 @c ==================================================================
2487 In some cases it might be necessary to add more routes to the virtual network
2488 interface. There are two ways to indicate which interface a packet should go
2489 to, one is to use the name of the interface itself, another way is to specify
2490 the (local) address that is assigned to that interface (@var{local_address}). The
2491 former way is unambiguous and therefore preferable, but not all platforms
2494 Adding routes to IPv4 subnets:
2496 @multitable {Darwin (MacOS/X)} {ifconfig route add -bla network address netmask netmask prefixlength interface}
2498 @tab @code{route add -net} @var{network_address} @code{netmask} @var{netmask} @var{interface}
2499 @item Linux iproute2
2500 @tab @code{ip route add} @var{network_address}@code{/}@var{prefixlength} @code{dev} @var{interface}
2502 @tab @code{route add} @var{network_address}@code{/}@var{prefixlength} @var{local_address}
2504 @tab @code{route add} @var{network_address}@code{/}@var{prefixlength} @var{local_address}
2506 @tab @code{route add} @var{network_address}@code{/}@var{prefixlength} @var{local_address}
2508 @tab @code{route add} @var{network_address}@code{/}@var{prefixlength} @var{local_address} @code{-interface}
2509 @item Darwin (MacOS/X)
2510 @tab @code{route add} @var{network_address}@code{/}@var{prefixlength} @var{local_address}
2512 @tab @code{netsh routing ip add persistentroute} @var{network_address} @var{netmask} @var{interface} @var{local_address}
2515 Adding routes to IPv6 subnets:
2517 @multitable {Darwin (MacOS/X)} {ifconfig route add -bla network address netmask netmask prefixlength interface}
2519 @tab @code{route add -A inet6} @var{network_address}@code{/}@var{prefixlength} @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 -inet6} @var{network_address}@code{/}@var{prefixlength} @var{local_address}
2525 @tab @code{route add -inet6} @var{network_address} @var{local_address} @code{-prefixlen} @var{prefixlength}
2527 @tab @code{route add -inet6} @var{network_address} @var{local_address} @code{-prefixlen} @var{prefixlength}
2529 @tab @code{route add -inet6} @var{network_address}@code{/}@var{prefixlength} @var{local_address} @code{-interface}
2530 @item Darwin (MacOS/X)
2533 @tab @code{netsh interface ipv6 add route} @var{network address}/@var{prefixlength} @var{interface}
2537 @c ==================================================================
2543 * Contact information::
2548 @c ==================================================================
2549 @node Contact information
2550 @section Contact information
2553 Tinc's website is at @url{http://www.tinc-vpn.org/},
2554 this server is located in the Netherlands.
2557 We have an IRC channel on the FreeNode and OFTC IRC networks. Connect to
2558 @uref{http://www.freenode.net/, irc.freenode.net}
2560 @uref{http://www.oftc.net/, irc.oftc.net}
2561 and join channel #tinc.
2564 @c ==================================================================
2569 @item Ivo Timmermans (zarq)
2570 @item Guus Sliepen (guus) (@email{guus@@tinc-vpn.org})
2573 We have received a lot of valuable input from users. With their help,
2574 tinc has become the flexible and robust tool that it is today. We have
2575 composed a list of contributions, in the file called @file{THANKS} in
2576 the source distribution.
2579 @c ==================================================================
2581 @unnumbered Concept Index
2583 @c ==================================================================
2587 @c ==================================================================