568 lines
29 KiB
Plaintext
568 lines
29 KiB
Plaintext
Remote Bridging with IP Tunnels mini-HOWTO
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Alexander Alekseev
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alex@zapad.msk.ru
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v1.0, May 12, 2002
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Revision History
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Revision 1.0 2002-05-12 Revised by: aa
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first release
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This document describes how to unite two separate ethernet LANs with an IP
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tunnel between them.
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-----------------------------------------------------------------------------
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Table of Contents
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1. How does it work?
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1.1. Bridging IP over ethernet traffic between 2 LANs.
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1.2. What about other protocols?
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2. Copyright
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2.1. GNU Free Documentation License
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2.2. PREAMBLE
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2.3. APPLICABILITY AND DEFINITIONS
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2.4. VERBATIM COPYING
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2.5. COPYING IN QUANTITY
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2.6. MODIFICATIONS
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2.7. COMBINING DOCUMENTS
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2.8. COLLECTIONS OF DOCUMENTS
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2.9. AGGREGATION WITH INDEPENDENT WORKS
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2.10. TRANSLATION
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2.11. TERMINATION
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2.12. FUTURE REVISIONS OF THIS LICENSE
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2.13. How to use this License for your documents
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1. How does it work?
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You can transparently bridge traffic between 2 ethernet LANs to unite them,
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if both of them are connected to Internet.
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There is no way to do a "real" bridge, you can only bridge third level
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protocols, which linux knows how to route, but ethernet traffic with those
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protocols will seem bridged. You can make 2 ethernet bridges, to bridge IP
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and/or IPX traffic. You cannot transparently bridge any other third level
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protocols between distinct LANs. You should read the rest of this document to
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determine whether you can bridge any other protocol.
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-----------------------------------------------------------------------------
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1.1. Bridging IP over ethernet traffic between 2 LANs.
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If you have:
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+---------------------------------------------------------------------------+
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|PC1 (192.168.0.1 /24)--| |
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|PC3 (192.168.0.3 /24)--| |
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|PC5 (192.168.0.5 /24)--|--[ eth0 - bridge_1 - eth1 (195.0.0.1) ] |
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| |
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|PC253 (192.168.0.253/24)--| |
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| | (192.168.0.2 /24) PC2 |
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| | (192.168.0.4 /24) PC4 |
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|[ (192.0.0.1) eth1 - bridge_2 - eth0 ] --| (192.168.0.6 /24) PC6 |
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| |
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| | (192.168.0.254/24) PC254 |
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+---------------------------------------------------------------------------+
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bridge_1 and bridge_2 are your Linux bridges and externally connected to the
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Internet interface eth1. So 195.0.0.1 and 192.0.0.1 can be any valid Internet
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addresses given to you by your ISP.
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So, you should:
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1. Get two linux computers with kernels 2.2 or 2.4. Kernels should be
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compiled with PPP and Advanced Router. You also need the iproute2 package
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properly installed. Information on iproute2 can be found in
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Configure.help of your kernel in the comments under Advanced Router. You
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also need the following utilities:
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<20><>+<2B>pppd (PPP daemon) - [ftp://cs.anu.edu.au/pub/software/ppp/] ftp://
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cs.anu.edu.au/pub/software/ppp/
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<20><>+<2B>PopTop (PPTP server) - [http://poptop.lineo.com/] http://
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poptop.lineo.com
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<20><>+<2B>PPTP (Linux PPTP Client, by C.S. Ananian) - [http://
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www.pdos.lcs.mit.edu/~cananian/Projects/PPTP/] http://
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www.pdos.lcs.mit.edu/~cananian/Projects/PPTP/
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<20><>+<2B>tarpd (a trivial proxy arp daemon) - [http://www.cs.hut.fi/~tricky/
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utils/net/tarpd-1.6.tar.gz] htp://www.cs.hut.fi/~tricky/utils/net/
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tarpd-1.6.tar.gz
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You can also find them on [http://www.freshmeat.net] http://
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www.freshmeat.net
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Please, keep in mind that you need special patches for pppd and the
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kernel if you want to do MS Chap and MS Encryption (MPPE). Refer to the
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PoPTop manual for instructions on how to get and install these patches.
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2. Connect your routers to Internet, or establish any other communication
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between them with the exception of IP.
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3. Make a PPTP tunnel between them. There are example configurations in the
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PoPToP (server) and pptp (client) manuals.
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4. Now you should have two bridges and an IP tunnel between then, possibly
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encrypted (refer to the PPP manual). Let's configure bridging.
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5. Remember that the bridge is really a router, so we need to run the
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following commands on our bridges (this assumes bridge_1 and bridge_2 are
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IP addresses, assigned to each end of the PPTP tunnel between bridges):
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+---------------------------------------------------------------+
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| bridge_1$ip route add 192.168.0.2 via bridge_2 |
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| bridge_1$ip route add 192.168.0.4 via bridge_2 |
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| bridge_1$ip route add 192.168.0.6 via bridge_2 |
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| |
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| bridge_1$ip route add 192.168.0.254 via bridge_2 |
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| bridge_1$ip route add 192.168.0.255 via bridge_2 |
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| |
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+---------------------------------------------------------------+
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On the other side:
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+---------------------------------------------------------------+
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| bridge_2$ip route add 192.168.0.1 via bridge_1 |
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| bridge_2$ip route add 192.168.0.3 via bridge_1 |
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| bridge_2$ip route add 192.168.0.5 via bridge_1 |
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| bridge_2$ip route add 192.168.0.253 via bridge_1 |
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+---------------------------------------------------------------+
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This will tell each of bridges which hosts are on the other side. You can
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do the same with the old-style route command. It will look like:
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+---------------------------------------------------------------+
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| bridge_1$route add -host 192.168.0.2 gw bridge_2 |
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| bridge_1$route add -host 192.168.0.4 gw bridge_2 |
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| bridge_1$route add -host 192.168.0.6 gw bridge_2 |
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| |
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| bridge_1$route add -host 192.168.0.254 gw bridge_2 |
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| bridge_1$route add -host 192.168.0.255 gw bridge_2 |
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+---------------------------------------------------------------+
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On the other side:
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+---------------------------------------------------------------+
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| bridge_2$route add -host 192.168.0.1 gw bridge_1 |
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| bridge_2$route add -host 192.168.0.3 gw bridge_1 |
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| bridge_2$route add -host 192.168.0.5 gw bridge_1 |
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| bridge_2$route add -host 192.168.0.253 gw bridge_1 |
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+---------------------------------------------------------------+
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Please note once more that bridge_1 and bridge_2 are not IP addresses
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given by your ISP, but IP addresses which you assigned to each end of the
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PPTP tunnel.
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6. Now you have two bridges and each of them knows where to find a
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particular IP. But how do you tell those computers to send their traffic
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for the remote network to the local bridge? You need tarpd.
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tarpd is a very simple daemon, which replies to arp requests for certain
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IP addresses. You only need to run a tarpd on each bridge, and specify
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the list of IP addresses found on the remote end.
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For example, for those two bridges you should run:
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+---------------------------------------------------------------+
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| bridge_1$tarpd eth0 192.168.0.2 255.255.255.255 \ |
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| 192.168.0.4 255.255.255.255 \ |
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| 192.168.0.254 255.255.255.255 |
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+---------------------------------------------------------------+
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On the other side:
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+---------------------------------------------------------------+
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| bridge_2$tarpd eth0 192.168.0.1 255.255.255.255 \ |
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| 192.168.0.3 255.255.255.255 \ |
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| 192.168.0.253 255.255.255.255 |
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+---------------------------------------------------------------+
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You specify 128 remote pairs (IP/mask. Mask should be 255.255.255.255 in
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order not to confuse tarpd!) on each bridge.
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7. Enjoy your bridges!
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-----------------------------------------------------------------------------
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1.2. What about other protocols?
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Really, I can say nothing about other protocol routing. I never used them.
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But I suppose if you are familiar with other protocols, it should not be too
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difficult to bridge it this way.
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-----------------------------------------------------------------------------
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2. Copyright
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Copyright <20> 2002 Alexander Alekseev
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Permission is granted to copy, distribute and/or modify this document under
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the terms of the GNU Free Documentation License, Version 1.1 or any later
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version published by the Free Software Foundation; with no Invariant
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Sections, no Front-Cover Texts, and no Back-Cover Texts. A copy of the
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license is included in the section entitled "GNU Free Documentation License".
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-----------------------------------------------------------------------------
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2.1. GNU Free Documentation License
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Version 1.1, March 2000
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Copyright (C) 2000 Free Software Foundation, Inc. 59 Temple Place, Suite
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330, Boston, MA 02111-1307 USA Everyone is permitted to copy and
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distribute verbatim copies of this license document, but changing it is
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not allowed.
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-----------------------------------------------------------------------------
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2.2. PREAMBLE
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The purpose of this License is to make a manual, textbook, or other written
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document "free" in the sense of freedom: to assure everyone the effective
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freedom to copy and redistribute it, with or without modifying it, either
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commercially or noncommercially. Secondarily, this License preserves for the
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author and publisher a way to get credit for their work, while not being
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considered responsible for modifications made by others.
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This License is a kind of "copyleft", which means that derivative works of
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the document must themselves be free in the same sense. It complements the
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GNU General Public License, which is a copyleft license designed for free
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software.
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We have designed this License in order to use it for manuals for free
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software, because free software needs free documentation: a free program
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should come with manuals providing the same freedoms that the software does.
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But this License is not limited to software manuals; it can be used for any
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printed book. We recommend this License principally for works whose purpose
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is instruction or reference.
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-----------------------------------------------------------------------------
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2.3. APPLICABILITY AND DEFINITIONS
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This License applies to any manual or other work that contains a notice
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placed by the copyright holder saying it can be distributed under the terms
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of this License. The "Document", below, refers to any such manual or work.
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Any member of the public is a licensee, and is addressed as "you".
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A "Modified Version" of the Document means any work containing the Document
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or a portion of it, either copied verbatim, or with modifications and/or
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A "Secondary Section" is a named appendix or a front-matter section of the
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Document that deals exclusively with the relationship of the publishers or
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The "Invariant Sections" are certain Secondary Sections whose titles are
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designated, as being those of Invariant Sections, in the notice that says
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The "Cover Texts" are certain short passages of text that are listed, as
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Front-Cover Texts or Back-Cover Texts, in the notice that says that the
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A "Transparent" copy of the Document means a machine-readable copy,
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Examples of suitable formats for Transparent copies include plain ASCII
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The "Title Page" means, for a printed book, the title page itself, plus such
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text.
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-----------------------------------------------------------------------------
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2.4. VERBATIM COPYING
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You may copy and distribute the Document in any medium, either commercially
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or noncommercially, provided that this License, the copyright notices, and
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the license notice saying this License applies to the Document are reproduced
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in all copies, and that you add no other conditions whatsoever to those of
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this License. You may not use technical measures to obstruct or control the
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reading or further copying of the copies you make or distribute. However, you
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may accept compensation in exchange for copies. If you distribute a large
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You may also lend copies, under the same conditions stated above, and you may
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publicly display copies.
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-----------------------------------------------------------------------------
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2.5. COPYING IN QUANTITY
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If you publish printed copies of the Document numbering more than 100, and
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the Document's license notice requires Cover Texts, you must enclose the
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copies in covers that carry, clearly and legibly, all these Cover Texts:
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Front-Cover Texts on the front cover, and Back-Cover Texts on the back cover.
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Both covers must also clearly and legibly identify you as the publisher of
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they preserve the title of the Document and satisfy these conditions, can be
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treated as verbatim copying in other respects.
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If the required texts for either cover are too voluminous to fit legibly, you
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should put the first ones listed (as many as fit reasonably) on the actual
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If you publish or distribute Opaque copies of the Document numbering more
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It is requested, but not required, that you contact the authors of the
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-----------------------------------------------------------------------------
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2.6. MODIFICATIONS
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You may copy and distribute a Modified Version of the Document under the
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conditions of sections 2 and 3 above, provided that you release the Modified
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A. Use in the Title Page (and on the covers, if any) a title distinct from
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if there were any, be listed in the History section of the Document). You
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may use the same title as a previous version if the original publisher of
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that version gives permission.
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B. List on the Title Page, as authors, one or more persons or entities
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responsible for authorship of the modifications in the Modified Version,
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together with at least five of the principal authors of the Document (all
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C. State on the Title page the name of the publisher of the Modified
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Version, as the publisher.
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D. Preserve all the copyright notices of the Document.
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E. Add an appropriate copyright notice for your modifications adjacent to
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F. Include, immediately after the copyright notices, a license notice giving
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G. Preserve in that license notice the full lists of Invariant Sections and
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required Cover Texts given in the Document's license notice.
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I. Preserve the section entitled "History", and its title, and add to it an
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J. Preserve the network location, if any, given in the Document for public
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These may be placed in the "History" section. You may omit a network
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therein.
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L. Preserve all the Invariant Sections of the Document, unaltered in their
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text and in their titles. Section numbers or the equivalent are not
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M. Delete any section entitled "Endorsements". Such a section may not be
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If the Modified Version includes new front-matter sections or appendices that
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qualify as Secondary Sections and contain no material copied from the
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Document, you may at your option designate some or all of these sections as
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invariant. To do this, add their titles to the list of Invariant Sections in
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the Modified Version's license notice. These titles must be distinct from any
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other section titles.
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You may add a section entitled "Endorsements", provided it contains nothing
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but endorsements of your Modified Version by various parties--for example,
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statements of peer review or that the text has been approved by an
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organization as the authoritative definition of a standard.
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You may add a passage of up to five words as a Front-Cover Text, and a
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passage of up to 25 words as a Back-Cover Text, to the end of the list of
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previously added by you or by arrangement made by the same entity you are
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acting on behalf of, you may not add another; but you may replace the old
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one, on explicit permission from the previous publisher that added the old
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one.
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The author(s) and publisher(s) of the Document do not by this License give
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permission to use their names for publicity for or to assert or imply
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endorsement of any Modified Version.
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-----------------------------------------------------------------------------
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|
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2.7. COMBINING DOCUMENTS
|
||
|
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You may combine the Document with other documents released under this
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License, under the terms defined in section 4 above for modified versions,
|
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provided that you include in the combination all of the Invariant Sections of
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all of the original documents, unmodified, and list them all as Invariant
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Sections of your combined work in its license notice.
|
||
|
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The combined work need only contain one copy of this License, and multiple
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||
identical Invariant Sections may be replaced with a single copy. If there are
|
||
multiple Invariant Sections with the same name but different contents, make
|
||
the title of each such section unique by adding at the end of it, in
|
||
parentheses, the name of the original author or publisher of that section if
|
||
known, or else a unique number. Make the same adjustment to the section
|
||
titles in the list of Invariant Sections in the license notice of the
|
||
combined work.
|
||
|
||
In the combination, you must combine any sections entitled "History" in the
|
||
various original documents, forming one section entitled "History"; likewise
|
||
combine any sections entitled "Acknowledgements", and any sections entitled
|
||
"Dedications". You must delete all sections entitled "Endorsements."
|
||
-----------------------------------------------------------------------------
|
||
|
||
2.8. COLLECTIONS OF DOCUMENTS
|
||
|
||
You may make a collection consisting of the Document and other documents
|
||
released under this License, and replace the individual copies of this
|
||
License in the various documents with a single copy that is included in the
|
||
collection, provided that you follow the rules of this License for verbatim
|
||
copying of each of the documents in all other respects.
|
||
|
||
You may extract a single document from such a collection, and distribute it
|
||
individually under this License, provided you insert a copy of this License
|
||
into the extracted document, and follow this License in all other respects
|
||
regarding verbatim copying of that document.
|
||
-----------------------------------------------------------------------------
|
||
|
||
2.9. AGGREGATION WITH INDEPENDENT WORKS
|
||
|
||
A compilation of the Document or its derivatives with other separate and
|
||
independent documents or works, in or on a volume of a storage or
|
||
distribution medium, does not as a whole count as a Modified Version of the
|
||
Document, provided no compilation copyright is claimed for the compilation.
|
||
Such a compilation is called an "aggregate", and this License does not apply
|
||
to the other self-contained works thus compiled with the Document, on account
|
||
of their being thus compiled, if they are not themselves derivative works of
|
||
the Document.
|
||
|
||
If the Cover Text requirement of section 3 is applicable to these copies of
|
||
the Document, then if the Document is less than one quarter of the entire
|
||
aggregate, the Document's Cover Texts may be placed on covers that surround
|
||
only the Document within the aggregate. Otherwise they must appear on covers
|
||
around the whole aggregate.
|
||
-----------------------------------------------------------------------------
|
||
|
||
2.10. TRANSLATION
|
||
|
||
Translation is considered a kind of modification, so you may distribute
|
||
translations of the Document under the terms of section 4. Replacing
|
||
Invariant Sections with translations requires special permission from their
|
||
copyright holders, but you may include translations of some or all Invariant
|
||
Sections in addition to the original versions of these Invariant Sections.
|
||
You may include a translation of this License provided that you also include
|
||
the original English version of this License. In case of a disagreement
|
||
between the translation and the original English version of this License, the
|
||
original English version will prevail.
|
||
-----------------------------------------------------------------------------
|
||
|
||
2.11. TERMINATION
|
||
|
||
You may not copy, modify, sublicense, or distribute the Document except as
|
||
expressly provided for under this License. Any other attempt to copy, modify,
|
||
sublicense or distribute the Document is void, and will automatically
|
||
terminate your rights under this License. However, parties who have received
|
||
copies, or rights, from you under this License will not have their licenses
|
||
terminated so long as such parties remain in full compliance.
|
||
-----------------------------------------------------------------------------
|
||
|
||
2.12. FUTURE REVISIONS OF THIS LICENSE
|
||
|
||
The Free Software Foundation may publish new, revised versions of the GNU
|
||
Free Documentation License from time to time. Such new versions will be
|
||
similar in spirit to the present version, but may differ in detail to address
|
||
new problems or concerns. See [http://www.gnu.org/copyleft/] http://
|
||
www.gnu.org/copyleft/.
|
||
|
||
Each version of the License is given a distinguishing version number. If the
|
||
Document specifies that a particular numbered version of this License "or any
|
||
later version" applies to it, you have the option of following the terms and
|
||
conditions either of that specified version or of any later version that has
|
||
been published (not as a draft) by the Free Software Foundation. If the
|
||
Document does not specify a version number of this License, you may choose
|
||
any version ever published (not as a draft) by the Free Software Foundation.
|
||
-----------------------------------------------------------------------------
|
||
|
||
2.13. How to use this License for your documents
|
||
|
||
To use this License in a document you have written, include a copy of the
|
||
License in the document and put the following copyright and license notices
|
||
just after the title page:
|
||
|
||
|
||
Copyright (c) YEAR YOUR NAME. Permission is granted to copy, distribute
|
||
and/or modify this document under the terms of the GNU Free Documentation
|
||
License, Version 1.1 or any later version published by the Free Software
|
||
Foundation; with the Invariant Sections being LIST THEIR TITLES, with the
|
||
Front-Cover Texts being LIST, and with the Back-Cover Texts being LIST. A
|
||
copy of the license is included in the section entitled "GNU Free
|
||
Documentation License".
|
||
|
||
If you have no Invariant Sections, write "with no Invariant Sections" instead
|
||
of saying which ones are invariant. If you have no Front-Cover Texts, write
|
||
"no Front-Cover Texts" instead of "Front-Cover Texts being LIST"; likewise
|
||
for Back-Cover Texts.
|
||
|
||
If your document contains nontrivial examples of program code, we recommend
|
||
releasing these examples in parallel under your choice of free software
|
||
license, such as the GNU General Public License, to permit their use in free
|
||
software.
|