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Revision: 1.1
Committed: Fri Jun 11 15:56:12 2004 UTC (19 years, 11 months ago) by pcg
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# Content
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131 .IX Title "GVPE 5"
132 .TH GVPE 5 "2004-06-11" "1.7" "GNU Virtual Private Ethernet"
133 .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 with 8 bytes of random data.
219 .PP
220 In general, remember that \s-1AES\-128\s0 seems to be more secure and faster than
221 \&\s-1AES\-192\s0 or \s-1AES\-256\s0, more randomness helps against sniffing and a longer
222 \&\s-1HMAC\s0 helps against spoofing. \s-1MD4\s0 is a fast digest, \s-1SHA1\s0 or \s-1RIPEMD160\s0 are
223 better, and Blowfish is a fast cipher (and also quite secure).
224 .SH "HOW TO SET UP A SIMPLE VPN"
225 .IX Header "HOW TO SET UP A SIMPLE VPN"
226 In this section I will describe how to get a simple \s-1VPN\s0 consisting of
227 three hosts up and running.
228 .Sh "\s-1STEP\s0 1: configuration"
229 .IX Subsection "STEP 1: configuration"
230 First you have to create a daemon configuation file and put it into the
231 configuration directory. This is usually \f(CW\*(C`/etc/gvpe\*(C'\fR, depending on how you
232 configured gvpe, and can be overwritten using the \f(CW\*(C`\-c\*(C'\fR commandline switch.
233 .PP
234 Put the following lines into \f(CW\*(C`/etc/gvpe/gvpe.conf\*(C'\fR:
235 .PP
236 .Vb 3
237 \& udp-port = 50000 # the external port to listen on (configure your firewall)
238 \& mtu = 1400 # minimum MTU of all outgoing interfaces on all hosts
239 \& ifname = vpn0 # the local network device name
240 .Ve
241 .PP
242 .Vb 2
243 \& node = first # just a nickname
244 \& hostname = first.example.net # the DNS name or IP address of the host
245 .Ve
246 .PP
247 .Vb 2
248 \& node = second
249 \& hostname = 133.55.82.9
250 .Ve
251 .PP
252 .Vb 2
253 \& node = third
254 \& hostname = third.example.net
255 .Ve
256 .PP
257 The only other file neccessary if the \f(CW\*(C`if\-up\*(C'\fR script that initializes the
258 local ethernet interface. Put the following lines into \f(CW\*(C`/etc/gvpe/if\-up\*(C'\fR
259 and make it execute (\f(CW\*(C`chmod 755 /etc/gvpe/if\-up\*(C'\fR):
260 .PP
261 .Vb 6
262 \& #!/bin/sh
263 \& ip link set $IFNAME address $MAC mtu $MTU up
264 \& [ $NODENAME = first ] && ip addr add 10.0.1.1 dev $IFNAME
265 \& [ $NODENAME = second ] && ip addr add 10.0.2.1 dev $IFNAME
266 \& [ $NODENAME = third ] && ip addr add 10.0.3.1 dev $IFNAME
267 \& ip route add 10.0.0.0/16 dev $IFNAME
268 .Ve
269 .PP
270 This script will give each node a different \s-1IP\s0 address in the \f(CW\*(C`10.0/16\*(C'\fR
271 network. The internal network (e.g. the \f(CW\*(C`eth0\*(C'\fR interface) should then be
272 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,
273 \&\f(CW\*(C`10.0.2.0/24\*(C'\fR on node \f(CW\*(C`second\*(C'\fR, and so on.
274 .PP
275 By enabling routing on the gateway host that runs \f(CW\*(C`gvpe\*(C'\fR all nodes will
276 be able to reach the other nodes. You can, of course, also use proxy arp
277 or other means of pseudo-bridging (or even real briding), or (best) full
278 routing \- the choice is yours.
279 .Sh "\s-1STEP\s0 2: create the \s-1RSA\s0 key pairs for all hosts"
280 .IX Subsection "STEP 2: create the RSA key pairs for all hosts"
281 Run the following command to generate all key pairs (that might take a
282 while):
283 .PP
284 .Vb 1
285 \& gvpectrl -c /etc/gvpe -g
286 .Ve
287 .PP
288 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.
289 .Sh "\s-1STEP\s0 3: distribute the config files to all nodes"
290 .IX Subsection "STEP 3: distribute the config files to all nodes"
291 Now distribute the config files to the other nodes. This should be done in two steps, since the
292 private keys should not be distributed. The example uses rsync-over-ssh
293 .PP
294 First all the config files without the hostkeys should be distributed:
295 .PP
296 .Vb 3
297 \& rsync -avzessh /etc/gvpe first.example.net:/etc/. --exclude hostkeys
298 \& rsync -avzessh /etc/gvpe 133.55.82.9:/etc/. --exclude hostkeys
299 \& rsync -avzessh /etc/gvpe third.example.net:/etc/. --exclude hostkeys
300 .Ve
301 .PP
302 Then the hostkeys should be copied:
303 .PP
304 .Vb 3
305 \& rsync -avzessh /etc/gvpe/hostkeys/first first.example.net:/etc/hostkey
306 \& rsync -avzessh /etc/gvpe/hostkeys/second 133.55.82.9:/etc/hostkey
307 \& rsync -avzessh /etc/gvpe/hostkeys/third third.example.net:/etc/hostkey
308 .Ve
309 .PP
310 You should now check the configration by issuing the command \f(CW\*(C`gvpectrl \-c
311 /etc/gvpe \-s\*(C'\fR on each node and verify it's output.
312 .Sh "\s-1STEP\s0 4: starting gvpe"
313 .IX Subsection "STEP 4: starting gvpe"
314 You should then start gvpe on each node by issuing a command like:
315 .PP
316 .Vb 1
317 \& gvpe -D -linfo first # first is the nodename
318 .Ve
319 .PP
320 This will make the gvpe stay in foreground. You should then see
321 \&\*(L"connection established\*(R" messages. If you don't see them check your
322 firewall and routing (use tcpdump ;).
323 .PP
324 If this works you should check your networking setup by pinging various
325 endpoints.
326 .PP
327 To make gvpe run more permanently you can either run it as a daemon
328 (by starting it without the \f(CW\*(C`\-D\*(C'\fR switch), or, much better, from your
329 inittab. I use a line like this on my systems:
330 .PP
331 .Vb 1
332 \& t1:2345:respawn:/opt/gvpe/sbin/gvpe -D -L first >/dev/null 2>&1
333 .Ve
334 .Sh "\s-1STEP\s0 5: enjoy"
335 .IX Subsection "STEP 5: enjoy"
336 \&... and play around. Sending a \-HUP (\f(CW\*(C`gvpectrl \-kHUP\*(C'\fR) to the daemon
337 will make it try to connect to all other nodes again. If you run it from
338 inittab, as is recommended, \f(CW\*(C`gvpectrl \-k\*(C'\fR (or simply \f(CW\*(C`killall gvpe\*(C'\fR) will
339 kill the daemon, start it again, making it read it's configuration files
340 again.
341 .SH "SEE ALSO"
342 .IX Header "SEE ALSO"
343 \&\fIgvpe.osdep\fR\|(5) for OS-depedendent information, \fIgvpe.conf\fR\|(5), \fIgvpectrl\fR\|(8), and
344 for a description of the protocol and routing algorithms, \fIgvpe.protocol\fR\|(7).
345 .SH "AUTHOR"
346 .IX Header "AUTHOR"
347 Marc Lehmann <gvpe@plan9.de>
348 .SH "COPYRIGHTS AND LICENSES"
349 .IX Header "COPYRIGHTS AND LICENSES"
350 \&\s-1GVPE\s0 itself is distributed under the \s-1GENERAL\s0 \s-1PUBLIC\s0 \s-1LICENSE\s0 (see the file
351 \&\s-1COPYING\s0 that should be part of your distribution).
352 .PP
353 In some configurations it uses modified versions of the tinc vpn suite,
354 which is also available under the \s-1GENERAL\s0 \s-1PUBLIC\s0 \s-1LICENSE\s0.