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Revision: 1.2
Committed: Thu Nov 11 17:41:55 2004 UTC (19 years, 6 months ago) by pcg
Branch: MAIN
Changes since 1.1: +4 -2 lines
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131     .IX Title "GVPE 5"
132 pcg 1.2 .TH GVPE 5 "2004-09-18" "1.7" "GNU Virtual Private Ethernet"
133 pcg 1.1 .SH "NAME"
134     GNU\-VPE \- Overview of the GNU Virtual Private Ethernet suite.
135     .SH "DESCRIPTION"
136     .IX Header "DESCRIPTION"
137     \&\s-1GVPE\s0 is a suite designed to provide a virtual private network for multiple
138     nodes over an untrusted network.
139     .PP
140     \&\*(L"Virtual\*(R" means that no physical network is created (of course), but an
141     ethernet is emulated by creating multiple tunnels between the member
142     nodes.
143     .IX Xref "Virtual"
144     .PP
145     \&\*(L"Private\*(R" means that non-participating nodes cannot decode (\*(L"sniff)\*(R" nor
146     inject (\*(L"spoof\*(R") packets.
147     .IX Xref "Private"
148     .PP
149     In the case of gvpe, even participating nodes cannot sniff packets send to
150     other nodes or spoof packets as if sent from other nodes.
151     .PP
152     \&\*(L"Network\*(R" means that more than two parties can participate in the
153     network, so for instance it's possible to connect multiple branches of a
154     company into a single network. Many so-called \*(L"vpn\*(R" solutions only create
155     point-to-point tunnels.
156     .IX Xref "Network"
157     .Sh "\s-1DESIGN\s0 \s-1GOALS\s0"
158     .IX Subsection "DESIGN GOALS"
159     .IP "\s-1SIMPLE\s0 \s-1DESIGN\s0" 4
160     .IX Item "SIMPLE DESIGN"
161     Cipher, \s-1HMAC\s0 algorithms and other key parameters must be selected
162     at compile time \- this makes it possible to only link in algorithms
163     you actually need. It also makes the crypto part of the source very
164     transparent and easy to inspect.
165     .IP "\s-1EASY\s0 \s-1TO\s0 \s-1SETUP\s0" 4
166     .IX Item "EASY TO SETUP"
167     A few lines of config (the config file is shared unmodified between all
168     hosts) and a single run of \f(CW\*(C`gvpectrl\*(C'\fR to generate the keys suffices to
169     make it work.
170     .IP "MAC-BASED \s-1SECURITY\s0" 4
171     .IX Item "MAC-BASED SECURITY"
172     Since every host has it's own private key, other hosts cannot spoof
173     traffic from this host. That makes it possible to filter packet by \s-1MAC\s0
174     address, e.g. to ensure that packets from a specific \s-1IP\s0 address come, in
175     fact, from a specific host that is associated with that \s-1IP\s0 and not from
176     another host.
177     .SH "PROGRAMS"
178     .IX Header "PROGRAMS"
179     Vpe comes with two programs: one daemon (\f(CW\*(C`gvpe\*(C'\fR) and one control program
180     (\f(CW\*(C`gvpectrl\*(C'\fR).
181     .IP "gvpectrl" 4
182     .IX Item "gvpectrl"
183     Is used to generate the keys, check and give an overview of of the
184     configuration and contorl the daemon (restarting etc.).
185     .IP "gvpe" 4
186     .IX Item "gvpe"
187     Is the daemon used to establish and maintain connections to the other
188     network members. It should be run on the gateway machine.
189     .SH "COMPILETIME CONFIGURATION"
190     .IX Header "COMPILETIME CONFIGURATION"
191     Please have a look at the \f(CW\*(C`gvpe.osdep(5)\*(C'\fR manpage for platform-specific
192     information.
193     .PP
194     Here are a few recipes for compiling your gvpe:
195     .Sh "\s-1AS\s0 \s-1LOW\s0 \s-1PACKET\s0 \s-1OVERHEAD\s0 \s-1AS\s0 \s-1POSSIBLE\s0"
196     .IX Subsection "AS LOW PACKET OVERHEAD AS POSSIBLE"
197     .Vb 1
198     \& ./configure --enable-hmac-length=4 --enable-rand-length=0
199     .Ve
200     .PP
201     Minimize the header overhead of \s-1VPN\s0 packets (the above will result in only
202     4 bytes of overhead over the raw ethernet frame).
203     .Sh "\s-1MINIMIZE\s0 \s-1CPU\s0 \s-1TIME\s0 \s-1REQUIRED\s0"
204     .IX Subsection "MINIMIZE CPU TIME REQUIRED"
205     .Vb 1
206     \& ./configure --enable-cipher=bf --enable-digest=md4
207     .Ve
208     .PP
209     Use the fastest cipher and digest algorithms currently available in gvpe.
210     .Sh "\s-1MAXIMIZE\s0 \s-1SECURITY\s0"
211     .IX Subsection "MAXIMIZE SECURITY"
212     .Vb 1
213     \& ./configure --enable-hmac-length=16 --enable-rand-length=8 --enable-digest=sha1
214     .Ve
215     .PP
216     This uses a 16 byte \s-1HMAC\s0 checksum to authenticate packets (I guess 8\-12
217     would also be pretty secure ;) and will additionally prefix each packet
218 pcg 1.2 with 8 bytes of random data. In the long run, people should move to
219     \&\s-1SHA\-224\s0 and beyond, but support in openssl is missing as of writing this
220     document.
221 pcg 1.1 .PP
222     In general, remember that \s-1AES\-128\s0 seems to be more secure and faster than
223     \&\s-1AES\-192\s0 or \s-1AES\-256\s0, more randomness helps against sniffing and a longer
224     \&\s-1HMAC\s0 helps against spoofing. \s-1MD4\s0 is a fast digest, \s-1SHA1\s0 or \s-1RIPEMD160\s0 are
225     better, and Blowfish is a fast cipher (and also quite secure).
226     .SH "HOW TO SET UP A SIMPLE VPN"
227     .IX Header "HOW TO SET UP A SIMPLE VPN"
228     In this section I will describe how to get a simple \s-1VPN\s0 consisting of
229     three hosts up and running.
230     .Sh "\s-1STEP\s0 1: configuration"
231     .IX Subsection "STEP 1: configuration"
232     First you have to create a daemon configuation file and put it into the
233     configuration directory. This is usually \f(CW\*(C`/etc/gvpe\*(C'\fR, depending on how you
234     configured gvpe, and can be overwritten using the \f(CW\*(C`\-c\*(C'\fR commandline switch.
235     .PP
236     Put the following lines into \f(CW\*(C`/etc/gvpe/gvpe.conf\*(C'\fR:
237     .PP
238     .Vb 3
239     \& udp-port = 50000 # the external port to listen on (configure your firewall)
240     \& mtu = 1400 # minimum MTU of all outgoing interfaces on all hosts
241     \& ifname = vpn0 # the local network device name
242     .Ve
243     .PP
244     .Vb 2
245     \& node = first # just a nickname
246     \& hostname = first.example.net # the DNS name or IP address of the host
247     .Ve
248     .PP
249     .Vb 2
250     \& node = second
251     \& hostname = 133.55.82.9
252     .Ve
253     .PP
254     .Vb 2
255     \& node = third
256     \& hostname = third.example.net
257     .Ve
258     .PP
259     The only other file neccessary if the \f(CW\*(C`if\-up\*(C'\fR script that initializes the
260     local ethernet interface. Put the following lines into \f(CW\*(C`/etc/gvpe/if\-up\*(C'\fR
261     and make it execute (\f(CW\*(C`chmod 755 /etc/gvpe/if\-up\*(C'\fR):
262     .PP
263     .Vb 6
264     \& #!/bin/sh
265     \& ip link set $IFNAME address $MAC mtu $MTU up
266     \& [ $NODENAME = first ] && ip addr add 10.0.1.1 dev $IFNAME
267     \& [ $NODENAME = second ] && ip addr add 10.0.2.1 dev $IFNAME
268     \& [ $NODENAME = third ] && ip addr add 10.0.3.1 dev $IFNAME
269     \& ip route add 10.0.0.0/16 dev $IFNAME
270     .Ve
271     .PP
272     This script will give each node a different \s-1IP\s0 address in the \f(CW\*(C`10.0/16\*(C'\fR
273     network. The internal network (e.g. the \f(CW\*(C`eth0\*(C'\fR interface) should then be
274     set to a subset of that network, e.g. \f(CW\*(C`10.0.1.0/24\*(C'\fR on node \f(CW\*(C`first\*(C'\fR,
275     \&\f(CW\*(C`10.0.2.0/24\*(C'\fR on node \f(CW\*(C`second\*(C'\fR, and so on.
276     .PP
277     By enabling routing on the gateway host that runs \f(CW\*(C`gvpe\*(C'\fR all nodes will
278     be able to reach the other nodes. You can, of course, also use proxy arp
279     or other means of pseudo-bridging (or even real briding), or (best) full
280     routing \- the choice is yours.
281     .Sh "\s-1STEP\s0 2: create the \s-1RSA\s0 key pairs for all hosts"
282     .IX Subsection "STEP 2: create the RSA key pairs for all hosts"
283     Run the following command to generate all key pairs (that might take a
284     while):
285     .PP
286     .Vb 1
287     \& gvpectrl -c /etc/gvpe -g
288     .Ve
289     .PP
290     This command will put the public keys into \f(CW\*(C`/etc/gvpe/pubkeys/\f(CInodename\f(CW\*(C'\fR and the private keys into \f(CW\*(C`/etc/gvpe/hostkeys/\f(CInodename\f(CW\*(C'\fR.
291     .Sh "\s-1STEP\s0 3: distribute the config files to all nodes"
292     .IX Subsection "STEP 3: distribute the config files to all nodes"
293     Now distribute the config files to the other nodes. This should be done in two steps, since the
294     private keys should not be distributed. The example uses rsync-over-ssh
295     .PP
296     First all the config files without the hostkeys should be distributed:
297     .PP
298     .Vb 3
299     \& rsync -avzessh /etc/gvpe first.example.net:/etc/. --exclude hostkeys
300     \& rsync -avzessh /etc/gvpe 133.55.82.9:/etc/. --exclude hostkeys
301     \& rsync -avzessh /etc/gvpe third.example.net:/etc/. --exclude hostkeys
302     .Ve
303     .PP
304     Then the hostkeys should be copied:
305     .PP
306     .Vb 3
307     \& rsync -avzessh /etc/gvpe/hostkeys/first first.example.net:/etc/hostkey
308     \& rsync -avzessh /etc/gvpe/hostkeys/second 133.55.82.9:/etc/hostkey
309     \& rsync -avzessh /etc/gvpe/hostkeys/third third.example.net:/etc/hostkey
310     .Ve
311     .PP
312     You should now check the configration by issuing the command \f(CW\*(C`gvpectrl \-c
313     /etc/gvpe \-s\*(C'\fR on each node and verify it's output.
314     .Sh "\s-1STEP\s0 4: starting gvpe"
315     .IX Subsection "STEP 4: starting gvpe"
316     You should then start gvpe on each node by issuing a command like:
317     .PP
318     .Vb 1
319     \& gvpe -D -linfo first # first is the nodename
320     .Ve
321     .PP
322     This will make the gvpe stay in foreground. You should then see
323     \&\*(L"connection established\*(R" messages. If you don't see them check your
324     firewall and routing (use tcpdump ;).
325     .PP
326     If this works you should check your networking setup by pinging various
327     endpoints.
328     .PP
329     To make gvpe run more permanently you can either run it as a daemon
330     (by starting it without the \f(CW\*(C`\-D\*(C'\fR switch), or, much better, from your
331     inittab. I use a line like this on my systems:
332     .PP
333     .Vb 1
334     \& t1:2345:respawn:/opt/gvpe/sbin/gvpe -D -L first >/dev/null 2>&1
335     .Ve
336     .Sh "\s-1STEP\s0 5: enjoy"
337     .IX Subsection "STEP 5: enjoy"
338     \&... and play around. Sending a \-HUP (\f(CW\*(C`gvpectrl \-kHUP\*(C'\fR) to the daemon
339     will make it try to connect to all other nodes again. If you run it from
340     inittab, as is recommended, \f(CW\*(C`gvpectrl \-k\*(C'\fR (or simply \f(CW\*(C`killall gvpe\*(C'\fR) will
341     kill the daemon, start it again, making it read it's configuration files
342     again.
343     .SH "SEE ALSO"
344     .IX Header "SEE ALSO"
345     \&\fIgvpe.osdep\fR\|(5) for OS-depedendent information, \fIgvpe.conf\fR\|(5), \fIgvpectrl\fR\|(8), and
346     for a description of the protocol and routing algorithms, \fIgvpe.protocol\fR\|(7).
347     .SH "AUTHOR"
348     .IX Header "AUTHOR"
349     Marc Lehmann <gvpe@plan9.de>
350     .SH "COPYRIGHTS AND LICENSES"
351     .IX Header "COPYRIGHTS AND LICENSES"
352     \&\s-1GVPE\s0 itself is distributed under the \s-1GENERAL\s0 \s-1PUBLIC\s0 \s-1LICENSE\s0 (see the file
353     \&\s-1COPYING\s0 that should be part of your distribution).
354     .PP
355     In some configurations it uses modified versions of the tinc vpn suite,
356     which is also available under the \s-1GENERAL\s0 \s-1PUBLIC\s0 \s-1LICENSE\s0.