[ViewVC] Annotation of: cvs/gvpe/README


==== NAME ====

    GNU-VPE - Overview of the GNU Virtual Private Ethernet suite.


==== DESCRIPTION ====

    GVPE is a suite designed to provide a virtual private network for
    multiple nodes over an untrusted network.

    "Virtual" means that no physical network is created (of course), but an
    ethernet is emulated by creating multiple tunnels between the member
    nodes.

    "Private" means that non-participating nodes cannot decode ("sniff)" nor
    inject ("spoof") packets.

    In the case of gvpe, even participating nodes cannot sniff packets send
    to other nodes or spoof packets as if sent from other nodes.

    "Network" means that more than two parties can participate in the
    network, so for instance it's possible to connect multiple branches of a
    company into a single network. Many so-called "vpn" solutions only
    create point-to-point tunnels.


==   DESIGN GOALS   ==

:   SIMPLE DESIGN
        Cipher, HMAC algorithms and other key parameters must be selected at
        compile time - this makes it possible to only link in algorithms you
        actually need. It also makes the crypto part of the source very
        transparent and easy to inspect.

:   EASY TO SETUP
        A few lines of config (the config file is shared unmodified between
        all hosts) and a single run of ``gvpectrl'' to generate the keys
        suffices to make it work.

:   MAC-BASED SECURITY
        Since every host has it's own private key, other hosts cannot spoof
        traffic from this host. That makes it possible to filter packet by
        MAC address, e.g. to ensure that packets from a specific IP address
        come, in fact, from a specific host that is associated with that IP
        and not from another host.


==== PROGRAMS ====

    Vpe comes with two programs: one daemon (``gvpe'') and one control
    program (``gvpectrl'').

:   gvpectrl
        Is used to generate the keys, check and give an overview of of the
        configuration and contorl the daemon (restarting etc.).

:   gvpe
        Is the daemon used to establish and maintain connections to the
        other network members. It should be run on the gateway machine.


==== COMPILETIME CONFIGURATION ====

    Please have a look at the ``gvpe.osdep(5)'' manpage for
    platform-specific information.

    Here are a few recipes for compiling your gvpe:


==   AS LOW PACKET OVERHEAD AS POSSIBLE   ==

       ./configure --enable-hmac-length=4 --enable-rand-length=0

    Minimize the header overhead of VPN packets (the above will result in
    only 4 bytes of overhead over the raw ethernet frame).


==   MINIMIZE CPU TIME REQUIRED   ==

       ./configure --enable-cipher=bf --enable-digest=md4

    Use the fastest cipher and digest algorithms currently available in
    gvpe.


==   MAXIMIZE SECURITY   ==

       ./configure --enable-hmac-length=16 --enable-rand-length=8 --enable-digest=sha1

    This uses a 16 byte HMAC checksum to authenticate packets (I guess 8-12
    would also be pretty secure ;) and will additionally prefix each packet
    with 8 bytes of random data.

    In general, remember that AES-128 seems to be more secure and faster
    than AES-192 or AES-256, more randomness helps against sniffing and a
    longer HMAC helps against spoofing. MD4 is a fast digest, SHA1 or
    RIPEMD160 are better, and Blowfish is a fast cipher (and also quite
    secure).


==== HOW TO SET UP A SIMPLE VPN ====

    In this section I will describe how to get a simple VPN consisting of
    three hosts up and running.


==   STEP 1: configuration   ==

    First you have to create a daemon configuation file and put it into the
    configuration directory. This is usually ``/etc/gvpe'', depending on how
    you configured gvpe, and can be overwritten using the ``-c'' commandline
    switch.

    Put the following lines into ``/etc/gvpe/gvpe.conf'':

       udp-port = 50000 # the external port to listen on (configure your firewall)
       mtu = 1400       # minimum MTU of all outgoing interfaces on all hosts
       ifname = vpn0    # the local network device name

       node = first     # just a nickname
       hostname = first.example.net # the DNS name or IP address of the host

       node = second
       hostname = 133.55.82.9

       node = third
       hostname = third.example.net

    The only other file neccessary if the ``if-up'' script that initializes
    the local ethernet interface. Put the following lines into
    ``/etc/gvpe/if-up'' and make it execute (``chmod 755 /etc/gvpe/if-up''):

       #!/bin/sh
       ip link set $IFNAME address $MAC mtu $MTU up
       [ $NODENAME = first  ] && ip addr add 10.0.1.1 dev $IFNAME
       [ $NODENAME = second ] && ip addr add 10.0.2.1 dev $IFNAME
       [ $NODENAME = third  ] && ip addr add 10.0.3.1 dev $IFNAME
       ip route add 10.0.0.0/16 dev $IFNAME

    This script will give each node a different IP address in the
    ``10.0/16'' network. The internal network (e.g. the ``eth0'' interface)
    should then be set to a subset of that network, e.g. ``10.0.1.0/24'' on
    node ``first'', ``10.0.2.0/24'' on node ``second'', and so on.

    By enabling routing on the gateway host that runs ``gvpe'' all nodes
    will be able to reach the other nodes. You can, of course, also use
    proxy arp or other means of pseudo-bridging (or even real briding), or
    (best) full routing - the choice is yours.


==   STEP 2: create the RSA key pairs for all hosts   ==

    Run the following command to generate all key pairs (that might take a
    while):

       gvpectrl -c /etc/gvpe -g

    This command will put the public keys into
    ``/etc/gvpe/pubkeys/*nodename*'' and the private keys into
    ``/etc/gvpe/hostkeys/*nodename*''.


==   STEP 3: distribute the config files to all nodes   ==

    Now distribute the config files to the other nodes. This should be done
    in two steps, since the private keys should not be distributed. The
    example uses rsync-over-ssh

    First all the config files without the hostkeys should be distributed:

       rsync -avzessh /etc/gvpe first.example.net:/etc/. --exclude hostkeys
       rsync -avzessh /etc/gvpe 133.55.82.9:/etc/. --exclude hostkeys
       rsync -avzessh /etc/gvpe third.example.net:/etc/. --exclude hostkeys

    Then the hostkeys should be copied:

       rsync -avzessh /etc/gvpe/hostkeys/first  first.example.net:/etc/hostkey
       rsync -avzessh /etc/gvpe/hostkeys/second 133.55.82.9:/etc/hostkey
       rsync -avzessh /etc/gvpe/hostkeys/third  third.example.net:/etc/hostkey

    You should now check the configration by issuing the command ``gvpectrl
    -c /etc/gvpe -s'' on each node and verify it's output.


==   STEP 4: starting gvpe   ==

    You should then start gvpe on each node by issuing a command like:

       gvpe -D -linfo first # first is the nodename

    This will make the gvpe stay in foreground. You should then see
    "connection established" messages. If you don't see them check your
    firewall and routing (use tcpdump ;).

    If this works you should check your networking setup by pinging various
    endpoints.

    To make gvpe run more permanently you can either run it as a daemon (by
    starting it without the ``-D'' switch), or, much better, from your
    inittab. I use a line like this on my systems:

       t1:2345:respawn:/opt/gvpe/sbin/gvpe -D -L first >/dev/null 2>&1


==   STEP 5: enjoy   ==

    ... and play around. Sending a -HUP (``gvpectrl -kHUP'') to the daemon
    will make it try to connect to all other nodes again. If you run it from
    inittab, as is recommended, ``gvpectrl -k'' (or simply ``killall gvpe'')
    will kill the daemon, start it again, making it read it's configuration
    files again.


==== SEE ALSO ====

    gvpe.osdep(5) for OS-depedendent information, gvpe.conf(5), gvpectrl(8),
    and for a description of the protocol and routing algorithms,
    gvpe.protocol(7).


==== AUTHOR ====

    Marc Lehmann <gvpe@plan9.de>


==== COPYRIGHTS AND LICENSES ====

    Vpe itself is distributed under the GENERAL PUBLIC LICENSE (see the file
    COPYING that should be part of your distribution).

    In some configurations it uses modified versions of the tinc vpn suite,
    which is also available under the GENERAL PUBLIC LICENSE.

    In some configurations (notably darwin), it uses a poll emulation
    library that comes with the following license notice:

      Copyright (c) 1995-2002 Brian M. Clapper
      All rights reserved.

      Redistribution and use in source and binary forms are permitted
      provided that: (1) source distributions retain this entire
      copyright notice and comment; (2) modifications made to the
      software are prominently mentioned, and a copy of the original
      software (or a pointer to its location) are included; and (3)
      distributions including binaries display the following
      acknowledgement: "This product includes software developed by Brian
      M. Clapper <bmc@clapper.org>" in the documentation or other
      materials provided with the distribution. The name of the author
      may not be used to endorse or promote products derived from this
      software without specific prior written permission.

      THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
      IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
      WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.

Revision:	1.7
Committed:	Fri Jun 11 15:56:03 2004 UTC (19 years, 11 months ago) by pcg
Branch:	MAIN
CVS Tags:	rel-1_7
Changes since 1.6:	+43 -41 lines
Log Message:	* empty log message *
#	User	Rev	Content
1	pcg	1.1
2	pcg	1.2	==== NAME ====
3
4	pcg	1.6	GNU-VPE - Overview of the GNU Virtual Private Ethernet suite.
5	pcg	1.2
6
7			==== DESCRIPTION ====
8
9	pcg	1.7	GVPE is a suite designed to provide a virtual private network for
10	pcg	1.2	multiple nodes over an untrusted network.
11
12			"Virtual" means that no physical network is created (of course), but an
13			ethernet is emulated by creating multiple tunnels between the member
14	pcg	1.4	nodes.
15
16			"Private" means that non-participating nodes cannot decode ("sniff)" nor
17			inject ("spoof") packets.
18
19	pcg	1.7	In the case of gvpe, even participating nodes cannot sniff packets send
20	pcg	1.4	to other nodes or spoof packets as if sent from other nodes.
21
22			"Network" means that more than two parties can participate in the
23			network, so for instance it's possible to connect multiple branches of a
24			company into a single network. Many so-called "vpn" solutions only
25			create point-to-point tunnels.
26	pcg	1.2
27
28			== DESIGN GOALS ==
29
30			: SIMPLE DESIGN
31			Cipher, HMAC algorithms and other key parameters must be selected at
32			compile time - this makes it possible to only link in algorithms you
33			actually need. It also makes the crypto part of the source very
34			transparent and easy to inspect.
35
36			: EASY TO SETUP
37			A few lines of config (the config file is shared unmodified between
38	pcg	1.7	all hosts) and a single run of ``gvpectrl'' to generate the keys
39	pcg	1.2	suffices to make it work.
40
41			: MAC-BASED SECURITY
42			Since every host has it's own private key, other hosts cannot spoof
43	pcg	1.7	traffic from this host. That makes it possible to filter packet by
44	pcg	1.2	MAC address, e.g. to ensure that packets from a specific IP address
45	pcg	1.7	come, in fact, from a specific host that is associated with that IP
46			and not from another host.
47	pcg	1.2
48
49			==== PROGRAMS ====
50
51	pcg	1.7	Vpe comes with two programs: one daemon (``gvpe'') and one control
52			program (``gvpectrl'').
53	pcg	1.2
54	pcg	1.7	: gvpectrl
55	pcg	1.3	Is used to generate the keys, check and give an overview of of the
56			configuration and contorl the daemon (restarting etc.).
57	pcg	1.2
58	pcg	1.7	: gvpe
59			Is the daemon used to establish and maintain connections to the
60	pcg	1.2	other network members. It should be run on the gateway machine.
61
62
63	pcg	1.3	==== COMPILETIME CONFIGURATION ====
64	pcg	1.2
65	pcg	1.7	Please have a look at the ``gvpe.osdep(5)'' manpage for
66			platform-specific information.
67	pcg	1.6
68	pcg	1.7	Here are a few recipes for compiling your gvpe:
69	pcg	1.2
70
71			== AS LOW PACKET OVERHEAD AS POSSIBLE ==
72
73	pcg	1.3	./configure --enable-hmac-length=4 --enable-rand-length=0
74	pcg	1.2
75	pcg	1.3	Minimize the header overhead of VPN packets (the above will result in
76			only 4 bytes of overhead over the raw ethernet frame).
77	pcg	1.2
78
79			== MINIMIZE CPU TIME REQUIRED ==
80
81	pcg	1.3	./configure --enable-cipher=bf --enable-digest=md4
82	pcg	1.2
83	pcg	1.7	Use the fastest cipher and digest algorithms currently available in
84			gvpe.
85	pcg	1.2
86
87			== MAXIMIZE SECURITY ==
88
89	pcg	1.3	./configure --enable-hmac-length=16 --enable-rand-length=8 --enable-digest=sha1
90
91			This uses a 16 byte HMAC checksum to authenticate packets (I guess 8-12
92			would also be pretty secure ;) and will additionally prefix each packet
93			with 8 bytes of random data.
94	pcg	1.2
95			In general, remember that AES-128 seems to be more secure and faster
96	pcg	1.3	than AES-192 or AES-256, more randomness helps against sniffing and a
97			longer HMAC helps against spoofing. MD4 is a fast digest, SHA1 or
98			RIPEMD160 are better, and Blowfish is a fast cipher (and also quite
99			secure).
100	pcg	1.2
101
102			==== HOW TO SET UP A SIMPLE VPN ====
103
104			In this section I will describe how to get a simple VPN consisting of
105			three hosts up and running.
106
107
108			== STEP 1: configuration ==
109
110			First you have to create a daemon configuation file and put it into the
111	pcg	1.7	configuration directory. This is usually ``/etc/gvpe'', depending on how
112			you configured gvpe, and can be overwritten using the ``-c'' commandline
113	pcg	1.2	switch.
114
115	pcg	1.7	Put the following lines into ``/etc/gvpe/gvpe.conf'':
116	pcg	1.2
117	pcg	1.3	udp-port = 50000 # the external port to listen on (configure your firewall)
118			mtu = 1400 # minimum MTU of all outgoing interfaces on all hosts
119			ifname = vpn0 # the local network device name
120	pcg	1.2
121	pcg	1.3	node = first # just a nickname
122			hostname = first.example.net # the DNS name or IP address of the host
123	pcg	1.2
124	pcg	1.3	node = second
125			hostname = 133.55.82.9
126	pcg	1.2
127	pcg	1.3	node = third
128			hostname = third.example.net
129	pcg	1.2
130			The only other file neccessary if the ``if-up'' script that initializes
131			the local ethernet interface. Put the following lines into
132	pcg	1.7	``/etc/gvpe/if-up'' and make it execute (``chmod 755 /etc/gvpe/if-up''):
133	pcg	1.2
134	pcg	1.3	#!/bin/sh
135			ip link set $IFNAME address $MAC mtu $MTU up
136			[ $NODENAME = first ] && ip addr add 10.0.1.1 dev $IFNAME
137			[ $NODENAME = second ] && ip addr add 10.0.2.1 dev $IFNAME
138			[ $NODENAME = third ] && ip addr add 10.0.3.1 dev $IFNAME
139			ip route add 10.0.0.0/16 dev $IFNAME
140	pcg	1.2
141			This script will give each node a different IP address in the
142			``10.0/16'' network. The internal network (e.g. the ``eth0'' interface)
143			should then be set to a subset of that network, e.g. ``10.0.1.0/24'' on
144			node ``first'', ``10.0.2.0/24'' on node ``second'', and so on.
145
146	pcg	1.7	By enabling routing on the gateway host that runs ``gvpe'' all nodes
147	pcg	1.2	will be able to reach the other nodes. You can, of course, also use
148			proxy arp or other means of pseudo-bridging (or even real briding), or
149			(best) full routing - the choice is yours.
150
151
152			== STEP 2: create the RSA key pairs for all hosts ==
153
154			Run the following command to generate all key pairs (that might take a
155			while):
156
157	pcg	1.7	gvpectrl -c /etc/gvpe -g
158	pcg	1.2
159			This command will put the public keys into
160	pcg	1.7	``/etc/gvpe/pubkeys/nodename'' and the private keys into
161			``/etc/gvpe/hostkeys/nodename''.
162	pcg	1.2
163
164			== STEP 3: distribute the config files to all nodes ==
165
166			Now distribute the config files to the other nodes. This should be done
167			in two steps, since the private keys should not be distributed. The
168			example uses rsync-over-ssh
169
170			First all the config files without the hostkeys should be distributed:
171
172	pcg	1.7	rsync -avzessh /etc/gvpe first.example.net:/etc/. --exclude hostkeys
173			rsync -avzessh /etc/gvpe 133.55.82.9:/etc/. --exclude hostkeys
174			rsync -avzessh /etc/gvpe third.example.net:/etc/. --exclude hostkeys
175	pcg	1.2
176			Then the hostkeys should be copied:
177
178	pcg	1.7	rsync -avzessh /etc/gvpe/hostkeys/first first.example.net:/etc/hostkey
179			rsync -avzessh /etc/gvpe/hostkeys/second 133.55.82.9:/etc/hostkey
180			rsync -avzessh /etc/gvpe/hostkeys/third third.example.net:/etc/hostkey
181	pcg	1.2
182	pcg	1.7	You should now check the configration by issuing the command ``gvpectrl
183			-c /etc/gvpe -s'' on each node and verify it's output.
184	pcg	1.2
185
186	pcg	1.7	== STEP 4: starting gvpe ==
187	pcg	1.2
188	pcg	1.7	You should then start gvpe on each node by issuing a command like:
189	pcg	1.2
190	pcg	1.7	gvpe -D -linfo first # first is the nodename
191	pcg	1.2
192	pcg	1.7	This will make the gvpe stay in foreground. You should then see
193	pcg	1.2	"connection established" messages. If you don't see them check your
194			firewall and routing (use tcpdump ;).
195
196			If this works you should check your networking setup by pinging various
197			endpoints.
198
199	pcg	1.7	To make gvpe run more permanently you can either run it as a daemon (by
200	pcg	1.2	starting it without the ``-D'' switch), or, much better, from your
201			inittab. I use a line like this on my systems:
202
203	pcg	1.7	t1:2345:respawn:/opt/gvpe/sbin/gvpe -D -L first >/dev/null 2>&1
204	pcg	1.2
205
206			== STEP 5: enjoy ==
207
208	pcg	1.7	... and play around. Sending a -HUP (``gvpectrl -kHUP'') to the daemon
209	pcg	1.2	will make it try to connect to all other nodes again. If you run it from
210	pcg	1.7	inittab, as is recommended, ``gvpectrl -k'' (or simply ``killall gvpe'')
211	pcg	1.2	will kill the daemon, start it again, making it read it's configuration
212			files again.
213
214
215			==== SEE ALSO ====
216
217	pcg	1.7	gvpe.osdep(5) for OS-depedendent information, gvpe.conf(5), gvpectrl(8),
218	pcg	1.6	and for a description of the protocol and routing algorithms,
219	pcg	1.7	gvpe.protocol(7).
220	pcg	1.2
221
222			==== AUTHOR ====
223
224	pcg	1.7	Marc Lehmann <gvpe@plan9.de>
225	pcg	1.6
226
227			==== COPYRIGHTS AND LICENSES ====
228
229			Vpe itself is distributed under the GENERAL PUBLIC LICENSE (see the file
230			COPYING that should be part of your distribution).
231
232			In some configurations it uses modified versions of the tinc vpn suite,
233			which is also available under the GENERAL PUBLIC LICENSE.
234
235			In some configurations (notably darwin), it uses a poll emulation
236			library that comes with the following license notice:
237
238			Copyright (c) 1995-2002 Brian M. Clapper
239			All rights reserved.
240
241			Redistribution and use in source and binary forms are permitted
242			provided that: (1) source distributions retain this entire
243			copyright notice and comment; (2) modifications made to the
244			software are prominently mentioned, and a copy of the original
245			software (or a pointer to its location) are included; and (3)
246			distributions including binaries display the following
247			acknowledgement: "This product includes software developed by Brian
248			M. Clapper <bmc@clapper.org>" in the documentation or other
249			materials provided with the distribution. The name of the author
250			may not be used to endorse or promote products derived from this
251			software without specific prior written permission.
252
253			THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
254			IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
255			WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
256	pcg	1.2