133 lines
6 KiB
Text
133 lines
6 KiB
Text
This is the README file for tinc version 1.0.35. Installation
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instructions may be found in the INSTALL file.
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tinc is Copyright (C) 1998-2018 by:
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Ivo Timmermans,
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Guus Sliepen <guus@tinc-vpn.org>,
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and others.
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For a complete list of authors see the AUTHORS file.
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or (at
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your option) any later version. See the file COPYING for more details.
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Security statement
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------------------
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In August 2000, we discovered the existence of a security hole in all versions
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of tinc up to and including 1.0pre2. This had to do with the way we exchanged
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keys. Since then, we have been working on a new authentication scheme to make
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tinc as secure as possible. The current version uses the OpenSSL library and
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uses strong authentication with RSA keys.
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On the 29th of December 2001, Jerome Etienne posted a security analysis of tinc
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1.0pre4. Due to a lack of sequence numbers and a message authentication code
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for each packet, an attacker could possibly disrupt certain network services or
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launch a denial of service attack by replaying intercepted packets. The current
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version adds sequence numbers and message authentication codes to prevent such
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attacks.
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On September the 15th of 2003, Peter Gutmann contacted us and showed us a
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writeup describing various security issues in several VPN daemons. He showed
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that tinc lacks perfect forward security, the connection authentication could
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be done more properly, that the sequence number we use as an IV is not the best
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practice and that the default length of the HMAC for packets is too short in
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his opinion. We do not know of a way to exploit these weaknesses, but these
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issues are being addressed in the tinc 1.1 branch.
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The Sweet32 attack affects versions of tinc prior to 1.0.30.
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On September 6th, 2018, Michael Yonly contacted us and provided
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proof-of-concept code that allowed a remote attacker to create an
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authenticated, one-way connection with a node, and also that there was a
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possibility for a man-in-the-middle to force UDP packets from a node to be sent
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in plaintext. The first issue was trivial to exploit on tinc versions prior to
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1.0.30, but the changes in 1.0.30 to mitigate the Sweet32 attack made this
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weakness much harder to exploit. These issues have been fixed in tinc 1.0.35.
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The new protocol in the tinc 1.1 branch is not susceptible to these issues.
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Cryptography is a hard thing to get right. We cannot make any
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guarantees. Time, review and feedback are the only things that can
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prove the security of any cryptographic product. If you wish to review
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tinc or give us feedback, you are strongly encouraged to do so.
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Compatibility
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-------------
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Version 1.0.35 is compatible with 1.0pre8, 1.0 and later, but not with older
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versions of tinc. Note that since version 1.0.30, tinc requires all nodes in
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the VPN to be compiled with a version of LibreSSL or OpenSSL that supports the
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AES256 and SHA256 algorithms.
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Requirements
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------------
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The OpenSSL library is used for all cryptographic functions. You can find it at
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https://www.openssl.org/. You will need version 1.0.1 or later with support for
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AES256 and SHA256 enabled. If this library is not installed on your system, the
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configure script will fail. The manual in doc/tinc.texi contains more detailed
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information on how to install this library. Alternatively, you may also use the
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LibreSSL library.
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The zlib library is used for optional compression. You can
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find it at https://zlib.net/. Because of a possible exploit in
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earlier versions we recommend that you download version 1.1.4 or later.
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The LZO library is also used for optional compression. You can
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find it at https://www.oberhumer.com/opensource/lzo/.
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In order to compile tinc, you will need a C99 compliant compiler.
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Features
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--------
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This version of tinc supports multiple virtual networks at once. To
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use this feature, you may supply a netname via the -n or --net
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options. The standard locations for the config files will then be
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/etc/tinc/<net>/.
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tincd regenerates its encryption key pairs. It does this on the first
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activity after the keys have expired. This period is adjustable in the
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configuration file, and the default time is 3600 seconds (one hour).
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This version supports multiple subnets at once. They are also sorted
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on subnet mask size. This means that it is possible to have
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overlapping subnets on the VPN, as long as their subnet mask sizes
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differ.
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Since pre5, tinc can operate in several routing modes. The default mode,
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"router", works exactly like the older version, and uses Subnet lines to
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determine the destination of packets. The other two modes, "switch" and "hub",
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allow the tinc daemons to work together like a single network switch or hub.
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This is useful for bridging networks. The latter modes only work properly on
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Linux, FreeBSD and Windows.
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The algorithms used for encryption and generating message authentication codes
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can now be changed in the configuration files. All cipher and digest algorithms
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supported by OpenSSL can be used. Useful ciphers are "blowfish" (default),
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"bf-ofb", "des", "des3", et cetera. Useful digests are "sha1" (default), "md5",
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et cetera.
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Support for routing IPv6 packets has been added. Just add Subnet lines with
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IPv6 addresses (without using :: abbreviations) and use ifconfig or ip (from
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the iproute package) to give the virtual network interface corresponding IPv6
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addresses. tinc does not provide autoconfiguration for IPv6 hosts. Consider
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using radvd or zebra if you need it.
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It is also possible to make tunnels to other tinc daemons over IPv6 networks,
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if the operating system supports IPv6. tinc will automatically use both IPv6
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and IPv4 when available, but this can be changed by adding the option
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"AddressFamily = ipv4" or "AddressFamily = ipv6" to the tinc.conf file.
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Normally, when started tinc will detach and run in the background. In a native
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Windows environment this means tinc will install itself as a service, which will
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restart after reboots. To prevent tinc from detaching or running as a service,
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use the -D option.
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