1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
|
<?xml version="1.0" encoding="utf-8" ?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<meta name="generator" content="Docutils 0.16: http://docutils.sourceforge.net/" />
<title>openvpn examples</title>
<style type="text/css">
/*
:Author: David Goodger (goodger@python.org)
:Id: $Id: html4css1.css 7952 2016-07-26 18:15:59Z milde $
:Copyright: This stylesheet has been placed in the public domain.
Default cascading style sheet for the HTML output of Docutils.
See http://docutils.sf.net/docs/howto/html-stylesheets.html for how to
customize this style sheet.
*/
/* used to remove borders from tables and images */
.borderless, table.borderless td, table.borderless th {
border: 0 }
table.borderless td, table.borderless th {
/* Override padding for "table.docutils td" with "! important".
The right padding separates the table cells. */
padding: 0 0.5em 0 0 ! important }
.first {
/* Override more specific margin styles with "! important". */
margin-top: 0 ! important }
.last, .with-subtitle {
margin-bottom: 0 ! important }
.hidden {
display: none }
.subscript {
vertical-align: sub;
font-size: smaller }
.superscript {
vertical-align: super;
font-size: smaller }
a.toc-backref {
text-decoration: none ;
color: black }
blockquote.epigraph {
margin: 2em 5em ; }
dl.docutils dd {
margin-bottom: 0.5em }
object[type="image/svg+xml"], object[type="application/x-shockwave-flash"] {
overflow: hidden;
}
/* Uncomment (and remove this text!) to get bold-faced definition list terms
dl.docutils dt {
font-weight: bold }
*/
div.abstract {
margin: 2em 5em }
div.abstract p.topic-title {
font-weight: bold ;
text-align: center }
div.admonition, div.attention, div.caution, div.danger, div.error,
div.hint, div.important, div.note, div.tip, div.warning {
margin: 2em ;
border: medium outset ;
padding: 1em }
div.admonition p.admonition-title, div.hint p.admonition-title,
div.important p.admonition-title, div.note p.admonition-title,
div.tip p.admonition-title {
font-weight: bold ;
font-family: sans-serif }
div.attention p.admonition-title, div.caution p.admonition-title,
div.danger p.admonition-title, div.error p.admonition-title,
div.warning p.admonition-title, .code .error {
color: red ;
font-weight: bold ;
font-family: sans-serif }
/* Uncomment (and remove this text!) to get reduced vertical space in
compound paragraphs.
div.compound .compound-first, div.compound .compound-middle {
margin-bottom: 0.5em }
div.compound .compound-last, div.compound .compound-middle {
margin-top: 0.5em }
*/
div.dedication {
margin: 2em 5em ;
text-align: center ;
font-style: italic }
div.dedication p.topic-title {
font-weight: bold ;
font-style: normal }
div.figure {
margin-left: 2em ;
margin-right: 2em }
div.footer, div.header {
clear: both;
font-size: smaller }
div.line-block {
display: block ;
margin-top: 1em ;
margin-bottom: 1em }
div.line-block div.line-block {
margin-top: 0 ;
margin-bottom: 0 ;
margin-left: 1.5em }
div.sidebar {
margin: 0 0 0.5em 1em ;
border: medium outset ;
padding: 1em ;
background-color: #ffffee ;
width: 40% ;
float: right ;
clear: right }
div.sidebar p.rubric {
font-family: sans-serif ;
font-size: medium }
div.system-messages {
margin: 5em }
div.system-messages h1 {
color: red }
div.system-message {
border: medium outset ;
padding: 1em }
div.system-message p.system-message-title {
color: red ;
font-weight: bold }
div.topic {
margin: 2em }
h1.section-subtitle, h2.section-subtitle, h3.section-subtitle,
h4.section-subtitle, h5.section-subtitle, h6.section-subtitle {
margin-top: 0.4em }
h1.title {
text-align: center }
h2.subtitle {
text-align: center }
hr.docutils {
width: 75% }
img.align-left, .figure.align-left, object.align-left, table.align-left {
clear: left ;
float: left ;
margin-right: 1em }
img.align-right, .figure.align-right, object.align-right, table.align-right {
clear: right ;
float: right ;
margin-left: 1em }
img.align-center, .figure.align-center, object.align-center {
display: block;
margin-left: auto;
margin-right: auto;
}
table.align-center {
margin-left: auto;
margin-right: auto;
}
.align-left {
text-align: left }
.align-center {
clear: both ;
text-align: center }
.align-right {
text-align: right }
/* reset inner alignment in figures */
div.align-right {
text-align: inherit }
/* div.align-center * { */
/* text-align: left } */
.align-top {
vertical-align: top }
.align-middle {
vertical-align: middle }
.align-bottom {
vertical-align: bottom }
ol.simple, ul.simple {
margin-bottom: 1em }
ol.arabic {
list-style: decimal }
ol.loweralpha {
list-style: lower-alpha }
ol.upperalpha {
list-style: upper-alpha }
ol.lowerroman {
list-style: lower-roman }
ol.upperroman {
list-style: upper-roman }
p.attribution {
text-align: right ;
margin-left: 50% }
p.caption {
font-style: italic }
p.credits {
font-style: italic ;
font-size: smaller }
p.label {
white-space: nowrap }
p.rubric {
font-weight: bold ;
font-size: larger ;
color: maroon ;
text-align: center }
p.sidebar-title {
font-family: sans-serif ;
font-weight: bold ;
font-size: larger }
p.sidebar-subtitle {
font-family: sans-serif ;
font-weight: bold }
p.topic-title {
font-weight: bold }
pre.address {
margin-bottom: 0 ;
margin-top: 0 ;
font: inherit }
pre.literal-block, pre.doctest-block, pre.math, pre.code {
margin-left: 2em ;
margin-right: 2em }
pre.code .ln { color: grey; } /* line numbers */
pre.code, code { background-color: #eeeeee }
pre.code .comment, code .comment { color: #5C6576 }
pre.code .keyword, code .keyword { color: #3B0D06; font-weight: bold }
pre.code .literal.string, code .literal.string { color: #0C5404 }
pre.code .name.builtin, code .name.builtin { color: #352B84 }
pre.code .deleted, code .deleted { background-color: #DEB0A1}
pre.code .inserted, code .inserted { background-color: #A3D289}
span.classifier {
font-family: sans-serif ;
font-style: oblique }
span.classifier-delimiter {
font-family: sans-serif ;
font-weight: bold }
span.interpreted {
font-family: sans-serif }
span.option {
white-space: nowrap }
span.pre {
white-space: pre }
span.problematic {
color: red }
span.section-subtitle {
/* font-size relative to parent (h1..h6 element) */
font-size: 80% }
table.citation {
border-left: solid 1px gray;
margin-left: 1px }
table.docinfo {
margin: 2em 4em }
table.docutils {
margin-top: 0.5em ;
margin-bottom: 0.5em }
table.footnote {
border-left: solid 1px black;
margin-left: 1px }
table.docutils td, table.docutils th,
table.docinfo td, table.docinfo th {
padding-left: 0.5em ;
padding-right: 0.5em ;
vertical-align: top }
table.docutils th.field-name, table.docinfo th.docinfo-name {
font-weight: bold ;
text-align: left ;
white-space: nowrap ;
padding-left: 0 }
/* "booktabs" style (no vertical lines) */
table.docutils.booktabs {
border: 0px;
border-top: 2px solid;
border-bottom: 2px solid;
border-collapse: collapse;
}
table.docutils.booktabs * {
border: 0px;
}
table.docutils.booktabs th {
border-bottom: thin solid;
text-align: left;
}
h1 tt.docutils, h2 tt.docutils, h3 tt.docutils,
h4 tt.docutils, h5 tt.docutils, h6 tt.docutils {
font-size: 100% }
ul.auto-toc {
list-style-type: none }
</style>
</head>
<body>
<div class="document" id="openvpn-examples">
<h1 class="title">openvpn examples</h1>
<h2 class="subtitle" id="secure-ip-tunnel-daemon">Secure IP tunnel daemon</h2>
<table class="docinfo" frame="void" rules="none">
<col class="docinfo-name" />
<col class="docinfo-content" />
<tbody valign="top">
<tr class="manual-section field"><th class="docinfo-name">Manual section:</th><td class="field-body">5</td>
</tr>
<tr class="manual-group field"><th class="docinfo-name">Manual group:</th><td class="field-body">Configuration files</td>
</tr>
</tbody>
</table>
<div class="section" id="introduction">
<h1>INTRODUCTION</h1>
<p>This man page gives a few simple examples to create OpenVPN setups and configuration files.</p>
</div>
<div class="section" id="examples">
<h1>EXAMPLES</h1>
<p>Prior to running these examples, you should have OpenVPN installed on
two machines with network connectivity between them. If you have not yet
installed OpenVPN, consult the INSTALL file included in the OpenVPN
distribution.</p>
<div class="section" id="firewall-setup">
<h2>Firewall Setup:</h2>
<p>If firewalls exist between the two machines, they should be set to
forward the port OpenVPN is configured to use, in both directions.
The default for OpenVPN is 1194/udp. If you do not have control
over the firewalls between the two machines, you may still be able to
use OpenVPN by adding <tt class="docutils literal"><span class="pre">--ping</span> 15</tt> to each of the <tt class="docutils literal">openvpn</tt> commands
used below in the examples (this will cause each peer to send out a UDP
ping to its remote peer once every 15 seconds which will cause many
stateful firewalls to forward packets in both directions without an
explicit firewall rule).</p>
<p>Please see your operating system guides for how to configure the firewall
on your systems.</p>
</div>
<div class="section" id="vpn-address-setup">
<h2>VPN Address Setup:</h2>
<p>For purposes of our example, our two machines will be called
<tt class="docutils literal">bob.example.com</tt> and <tt class="docutils literal">alice.example.com</tt>. If you are constructing a
VPN over the internet, then replace <tt class="docutils literal">bob.example.com</tt> and
<tt class="docutils literal">alice.example.com</tt> with the internet hostname or IP address that each
machine will use to contact the other over the internet.</p>
<p>Now we will choose the tunnel endpoints. Tunnel endpoints are private IP
addresses that only have meaning in the context of the VPN. Each machine
will use the tunnel endpoint of the other machine to access it over the
VPN. In our example, the tunnel endpoint for bob.example.com will be
10.4.0.1 and for alice.example.com, 10.4.0.2.</p>
<p>Once the VPN is established, you have essentially created a secure
alternate path between the two hosts which is addressed by using the
tunnel endpoints. You can control which network traffic passes between
the hosts (a) over the VPN or (b) independently of the VPN, by choosing
whether to use (a) the VPN endpoint address or (b) the public internet
address, to access the remote host. For example if you are on
bob.example.com and you wish to connect to <tt class="docutils literal">alice.example.com</tt> via
<tt class="docutils literal">ssh</tt> without using the VPN (since <strong>ssh</strong> has its own built-in security)
you would use the command <tt class="docutils literal">ssh alice.example.com</tt>. However in the same
scenario, you could also use the command <tt class="docutils literal">telnet 10.4.0.2</tt> to create a
telnet session with alice.example.com over the VPN, that would use the
VPN to secure the session rather than <tt class="docutils literal">ssh</tt>.</p>
<p>You can use any address you wish for the tunnel endpoints but make sure
that they are private addresses (such as those that begin with 10 or
192.168) and that they are not part of any existing subnet on the
networks of either peer, unless you are bridging. If you use an address
that is part of your local subnet for either of the tunnel endpoints,
you will get a weird feedback loop.</p>
</div>
<div class="section" id="example-1-a-simple-tunnel-without-security">
<h2>Example 1: A simple tunnel without security</h2>
<p>On bob:</p>
<pre class="literal-block">
openvpn --remote alice.example.com --dev tun1 \
--ifconfig 10.4.0.1 10.4.0.2 --verb 9
</pre>
<p>On alice:</p>
<pre class="literal-block">
openvpn --remote bob.example.com --dev tun1 \
--ifconfig 10.4.0.2 10.4.0.1 --verb 9
</pre>
<p>Now verify the tunnel is working by pinging across the tunnel.</p>
<p>On bob:</p>
<pre class="literal-block">
ping 10.4.0.2
</pre>
<p>On alice:</p>
<pre class="literal-block">
ping 10.4.0.1
</pre>
<p>The <tt class="docutils literal"><span class="pre">--verb</span> 9</tt> option will produce verbose output, similar to the
<tt class="docutils literal">tcpdump</tt>(8) program. Omit the <tt class="docutils literal"><span class="pre">--verb</span> 9</tt> option to have OpenVPN run
quietly.</p>
</div>
<div class="section" id="example-2-a-tunnel-with-static-key-security-i-e-using-a-pre-shared-secret">
<h2>Example 2: A tunnel with static-key security (i.e. using a pre-shared secret)</h2>
<p>First build a static key on bob.</p>
<pre class="literal-block">
openvpn --genkey --secret key
</pre>
<p>This command will build a key file called <tt class="docutils literal">key</tt> (in ascii format). Now
copy <tt class="docutils literal">key</tt> to <tt class="docutils literal">alice.example.com</tt> over a secure medium such as by using
the <tt class="docutils literal">scp</tt>(1) program.</p>
<p>On bob:</p>
<pre class="literal-block">
openvpn --remote alice.example.com --dev tun1 \
--ifconfig 10.4.0.1 10.4.0.2 --verb 5 \
--secret key
</pre>
<p>On alice:</p>
<pre class="literal-block">
openvpn --remote bob.example.com --dev tun1 \
--ifconfig 10.4.0.2 10.4.0.1 --verb 5 \
--secret key
</pre>
<p>Now verify the tunnel is working by pinging across the tunnel.</p>
<p>On bob:</p>
<pre class="literal-block">
ping 10.4.0.2
</pre>
<p>On alice:</p>
<pre class="literal-block">
ping 10.4.0.1
</pre>
</div>
<div class="section" id="example-3-a-tunnel-with-full-tls-based-security">
<h2>Example 3: A tunnel with full TLS-based security</h2>
<p>For this test, we will designate <tt class="docutils literal">bob</tt> as the TLS client and <tt class="docutils literal">alice</tt>
as the TLS server.</p>
<dl class="docutils">
<dt><em>Note:</em></dt>
<dd>The client or server designation only has
meaning for the TLS subsystem. It has no bearing on OpenVPN's
peer-to-peer, UDP-based communication model.*</dd>
</dl>
<p>First, build a separate certificate/key pair for both bob and alice (see
above where <tt class="docutils literal"><span class="pre">--cert</span></tt> is discussed for more info). Then construct
Diffie Hellman parameters (see above where <tt class="docutils literal"><span class="pre">--dh</span></tt> is discussed for
more info). You can also use the included test files <code>client.crt</code>,
<code>client.key</code>, <code>server.crt</code>, <code>server.key</code> and
<code>ca.crt</code>. The <tt class="docutils literal">.crt</tt> files are certificates/public-keys, the
<tt class="docutils literal">.key</tt> files are private keys, and <code>ca.crt</code> is a certification
authority who has signed both <code>client.crt</code> and <code>server.crt</code>.
For Diffie Hellman parameters you can use the included file
<code>dh2048.pem</code>.</p>
<dl class="docutils">
<dt><em>WARNING:</em></dt>
<dd>All client, server, and certificate authority certificates
and keys included in the OpenVPN distribution are totally
insecure and should be used for testing only.</dd>
</dl>
<p>On bob:</p>
<pre class="literal-block">
openvpn --remote alice.example.com --dev tun1 \
--ifconfig 10.4.0.1 10.4.0.2 \
--tls-client --ca ca.crt \
--cert client.crt --key client.key \
--reneg-sec 60 --verb 5
</pre>
<p>On alice:</p>
<pre class="literal-block">
openvpn --remote bob.example.com --dev tun1 \
--ifconfig 10.4.0.2 10.4.0.1 \
--tls-server --dh dh1024.pem --ca ca.crt \
--cert server.crt --key server.key \
--reneg-sec 60 --verb 5
</pre>
<p>Now verify the tunnel is working by pinging across the tunnel.</p>
<p>On bob:</p>
<pre class="literal-block">
ping 10.4.0.2
</pre>
<p>On alice:</p>
<pre class="literal-block">
ping 10.4.0.1
</pre>
<p>Notice the <tt class="docutils literal"><span class="pre">--reneg-sec</span> 60</tt> option we used above. That tells OpenVPN
to renegotiate the data channel keys every minute. Since we used
<tt class="docutils literal"><span class="pre">--verb</span> 5</tt> above, you will see status information on each new key
negotiation.</p>
<p>For production operations, a key renegotiation interval of 60 seconds is
probably too frequent. Omit the <tt class="docutils literal"><span class="pre">--reneg-sec</span> 60</tt> option to use
OpenVPN's default key renegotiation interval of one hour.</p>
</div>
<div class="section" id="routing">
<h2>Routing:</h2>
<p>Assuming you can ping across the tunnel, the next step is to route a
real subnet over the secure tunnel. Suppose that bob and alice have two
network interfaces each, one connected to the internet, and the other to
a private network. Our goal is to securely connect both private
networks. We will assume that bob's private subnet is <em>10.0.0.0/24</em> and
alice's is <em>10.0.1.0/24</em>.</p>
<p>First, ensure that IP forwarding is enabled on both peers. On Linux,
enable routing:</p>
<pre class="literal-block">
echo 1 > /proc/sys/net/ipv4/ip_forward
</pre>
<p>This setting is not persistent. Please see your operating systems
documentation how to properly configure IP forwarding, which is also
persistent through system boots.</p>
<p>If your system is configured with a firewall. Please see your operating
systems guide on how to configure the firewall. You typically want to
allow traffic coming from and going to the tun/tap adapter OpenVPN is
configured to use.</p>
<p>On bob:</p>
<pre class="literal-block">
route add -net 10.0.1.0 netmask 255.255.255.0 gw 10.4.0.2
</pre>
<p>On alice:</p>
<pre class="literal-block">
route add -net 10.0.0.0 netmask 255.255.255.0 gw 10.4.0.1
</pre>
<p>Now any machine on the <em>10.0.0.0/24</em> subnet can access any machine on the
<em>10.0.1.0/24</em> subnet over the secure tunnel (or vice versa).</p>
<p>In a production environment, you could put the route command(s) in a
script and execute with the <tt class="docutils literal"><span class="pre">--up</span></tt> option.</p>
</div>
</div>
</div>
</body>
</html>
|
