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98716a227e
Currently, the PMTU discovery code is run by a timeout callback, independently of tunnel activity. This commit moves it into the TX path, meaning that send_mtu_probe_handler() is only called if a packet is about to be sent. Consequently, it has been renamed to try_mtu() for consistency with try_tx(), try_udp() and try_sptps(). Running PMTU discovery code only as part of the TX path prevents PMTU discovery from generating unreasonable amounts of traffic when the "real" traffic is negligible. One extreme example is sending one real packet and then going silent: in the current code this one little packet will result in the entire PMTU discovery algorithm being run from start to finish, resulting in absurd write traffic amplification. With this patch, PMTU discovery stops as soon as "real" packets stop flowing, and will be no more aggressive than the underlying traffic. Furthermore, try_mtu() only runs if there is confirmed UDP connectivity as per the UDP discovery mechanism. This prevents unnecessary network chatter - previously, the PMTU discovery code would send bursts of (potentially large) probe packets every second even if there was nothing on the other side. With this patch, the PMTU code only does that if something replied to the lightweight UDP discovery pings. These inefficiencies were made even worse when the node is not a direct neighbour, as tinc will use PMTU discovery both on the destination node *and* the relay. UDP discovery is more lightweight for this purpose. As a bonus, this code simplifies overall code somewhat - state is easier to manage when code is run in predictable contexts as opposed to "surprise callbacks". In addition, there is no need to call PMTU discovery code outside of net_packet.c anymore, thereby simplifying module boundaries. |
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| bash_completion.d | ||
| doc | ||
| gui | ||
| m4 | ||
| src | ||
| test | ||
| .gitignore | ||
| AUTHORS | ||
| configure.ac | ||
| COPYING | ||
| COPYING.README | ||
| Makefile.am | ||
| NEWS | ||
| README | ||
| README.android | ||
| README.git | ||
| THANKS | ||
This is the README file for tinc version 1.1pre11. Installation instructions may be found in the INSTALL file. tinc is Copyright (C) 1998-2014 by: Ivo Timmermans, Guus Sliepen <guus@tinc-vpn.org>, and others. For a complete list of authors see the AUTHORS file. This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. See the file COPYING for more details. This is a pre-release --------------------- Please note that this is NOT a stable release. Until version 1.1.0 is released, please use one of the 1.0.x versions if you need a stable version of tinc. Although tinc 1.1 will be protocol compatible with tinc 1.0.x, the functionality of the tinc program may still change, and the control socket protocol is not fixed yet. Security statement ------------------ This version uses an experimental and unfinished cryptographic protocol. Use it at your own risk. Compatibility ------------- Version 1.1pre11 is compatible with 1.0pre8, 1.0 and later, but not with older versions of tinc. When the ExperimentalProtocol option is used, tinc is still compatible with 1.0.X and 1.1pre11 itself, but not with any other 1.1preX version. Requirements ------------ In order to compile tinc, you will need a GNU C compiler environment. Please ensure you have the latest stable versions of all the required libraries: - OpenSSL (http://www.openssl.org/) version 1.0.0 or later, with support for elliptic curve cryptography (ECC) and Galois counter mode (GCM) enabled. The following libraries are used by default, but can be disabled if necessary: - zlib (http://www.gzip.org/zlib/) - lzo (http://www.oberhumer.com/opensource/lzo/) - ncurses (http://invisible-island.net/ncurses/) - readline (ftp://ftp.gnu.org/pub/gnu/readline/) Features -------- Tinc is a peer-to-peer VPN daemon that supports VPNs with an arbitrary number of nodes. Instead of configuring tunnels, you give tinc the location and public key of a few nodes in the VPN. After making the initial connections to those nodes, tinc will learn about all other nodes on the VPN, and will make connections automatically. When direct connections are not possible, data will be forwarded by intermediate nodes. By default, nodes authenticate each other using 2048 bit RSA (or 521 bit ECDSA*) keys. Traffic is encrypted using Blowfish in CBC mode (or AES-256 in GCM mode*), authenticated using HMAC-SHA1 (or GCM*), and is protected against replay attacks. *) When using the ExperimentalProtocol option. Tinc fully supports IPv6. Tinc can operate in several routing modes. In the default mode, "router", every node is associated with one or more IPv4 and/or IPv6 Subnets. The other two modes, "switch" and "hub", let the tinc daemons work together to form a virtual Ethernet network switch or hub. Normally, when started tinc will detach and run in the background. In a native Windows environment this means tinc will intall itself as a service, which will restart after reboots. To prevent tinc from detaching or running as a service, use the -D option. The status of the VPN can be queried using the "tinc" command, which connects to a running tinc daemon via a control connection. The same tool also makes it easy to start and stop tinc, and to change its configuration.