summaryrefslogtreecommitdiff
path: root/bitmask_android/openvpn/doc/management-notes.txt
blob: ef39b8553913d13fc4af4a05d146b958da331126 (plain)
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
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
OpenVPN Management Interface Notes
----------------------------------

The OpenVPN Management interface allows OpenVPN to
be administratively controlled from an external program via
a TCP or unix domain socket.

The interface has been specifically designed for developers
who would like to programmatically or remotely control
an OpenVPN daemon, and can be used when OpenVPN is running
as a client or server.

The management interface is implemented using a client/server TCP
connection or unix domain socket where OpenVPN will listen on a
provided IP address and port for incoming management client connections.

The management protocol is currently cleartext without an explicit
security layer.  For this reason, it is recommended that the
management interface either listen on a unix domain socket,
localhost (127.0.0.1), or on the local VPN address.  It's possible
to remotely connect to the management interface over the VPN itself,
though some capabilities will be limited in this mode, such as the
ability to provide private key passwords.

The management interface is enabled in the OpenVPN
configuration file using the following directive:

--management

See the man page for documentation on this and related
directives.

Once OpenVPN has started with the management layer enabled,
you can telnet to the management port (make sure to use
a telnet client which understands "raw" mode).

Once connected to the management port, you can use
the "help" command to list all commands.

COMMAND -- bytecount
--------------------

The bytecount command is used to request real-time notification
of OpenVPN bandwidth usage.

Command syntax:

  bytecount n (where n > 0) -- set up automatic notification of
                               bandwidth usage once every n seconds
  bytecount 0 -- turn off bytecount notifications

If OpenVPN is running as a client, the bytecount notification
will look like this:

  >BYTECOUNT:{BYTES_IN},{BYTES_OUT}

BYTES_IN is the number of bytes that have been received from
the server and BYTES_OUT is the number of bytes that have been
sent to the server.

If OpenVPN is running as a server, the bytecount notification
will look like this:

  >BYTECOUNT_CLI:{CID},{BYTES_IN},{BYTES_OUT}
 
CID is the Client ID, BYTES_IN is the number of bytes that have
been received from the client and BYTES_OUT is the number of
bytes that have been sent to the client.

Note that when the bytecount command is used on the server, every
connected client will report its bandwidth numbers once every n
seconds.

When the client disconnects, the final bandwidth numbers will be
placed in the 'bytes_received' and 'bytes_sent' environmental variables
as included in the >CLIENT:DISCONNECT notification.

COMMAND -- echo
---------------

The echo capability is used to allow GUI-specific
parameters to be either embedded in the OpenVPN config file
or pushed to an OpenVPN client from a server.

Command examples:

  echo on      -- turn on real-time notification of echo messages
  echo all     -- print the current echo history list
  echo off     -- turn off real-time notification of echo messages
  echo on all  -- atomically enable real-time notification,
                  plus show any messages in history buffer

For example, suppose you are developing a OpenVPN GUI and
you want to give the OpenVPN server the ability to ask
the GUI to forget any saved passwords.

In the OpenVPN server config file, add:

  push "echo forget-passwords"

When the OpenVPN client receives its pulled list of directives
from the server, the "echo forget-passwords" directive will
be in the list, and it will cause the management interface
to save the "forget-passwords" string in its list of echo
parameters.

The management client can use "echo all" to output the full
list of echoed parameters, "echo on" to turn on real-time
notification of echoed parameters via the ">ECHO:" prefix,
or "echo off" to turn off real-time notification.

When the GUI connects to the OpenVPN management socket, it
can issue an "echo all" command, which would produce output
like this:

  1101519562,forget-passwords
  END

Essentially the echo command allowed us to pass parameters from
the OpenVPN server to the OpenVPN client, and then to the
management client (such as a GUI).  The large integer is the
unix date/time when the echo parameter was received.

If the management client had issued the command "echo on",
it would have enabled real-time notifications of echo
parameters.  In this case, our "forget-passwords" message
would be output like this:

  >ECHO:1101519562,forget-passwords

Like the log command, the echo command can atomically show
history while simultaneously activating real-time updates:

  echo on all

The size of the echo buffer is currently hardcoded to 100
messages.

COMMAND -- exit, quit
---------------------

Close the managment session, and resume listening on the
management port for connections from other clients. Currently,
the OpenVPN daemon can at most support a single management client
any one time.

COMMAND -- help
---------------

Print a summary of commands.

COMMAND -- hold
---------------

The hold command can be used to manipulate the hold flag,
or release OpenVPN from a hold state.

If the hold flag is set on initial startup or
restart, OpenVPN will hibernate prior to initializing
the tunnel until the management interface receives
a "hold release" command.

The --management-hold directive of OpenVPN can be used
to start OpenVPN with the hold flag set.

The hold flag setting is persistent and will not
be reset by restarts.

OpenVPN will indicate that it is in a hold state by
sending a real-time notification to the management
client:

  >HOLD:Waiting for hold release

Command examples:

  hold         -- show current hold flag, 0=off, 1=on.
  hold on      -- turn on hold flag so that future restarts
                  will hold.
  hold off     -- turn off hold flag so that future restarts will
                  not hold.
  hold release -- leave hold state and start OpenVPN, but
                  do not alter the current hold flag setting.

COMMAND -- kill
---------------

In server mode, kill a particlar client instance.

Command examples:

  kill Test-Client -- kill the client instance having a
                      common name of "Test-Client".
  kill 1.2.3.4:4000 -- kill the client instance having a
                       source address and port of 1.2.3.4:4000

Use the "status" command to see which clients are connected.

COMMAND -- log
--------------

Show the OpenVPN log file.  Only the most recent n lines
of the log file are cached by the management interface, where
n is controlled by the OpenVPN --management-log-cache directive.

Command examples:

  log on     -- Enable real-time output of log messages.
  log all    -- Show currently cached log file history.
  log on all -- Atomically show all currently cached log file
                history then enable real-time notification of
                new log file messages.
  log off    -- Turn off real-time notification of log messages.
  log 20     -- Show the most recent 20 lines of log file history.

Real-time notification format:

Real-time log messages begin with the ">LOG:" prefix followed
by the following comma-separated fields:

  (a) unix integer date/time,
  (b) zero or more message flags in a single string:
      I -- informational
      F -- fatal error
      N -- non-fatal error
      W -- warning
      D -- debug, and
  (c) message text.

COMMAND -- mute
---------------

Change the OpenVPN --mute parameter.  The mute parameter is
used to silence repeating messages of the same message
category.

Command examples:

  mute 40 -- change the mute parameter to 40
  mute    -- show the current mute setting

COMMAND -- net
--------------

(Windows Only) Produce output equivalent to the OpenVPN
--show-net directive.  The output includes OpenVPN's view
of the system network adapter list and routing table based
on information returned by the Windows IP helper API.

COMMAND -- pid
--------------

Shows the process ID of the current OpenVPN process.

COMMAND -- password and username
--------------------------------

  The password command is used to pass passwords to OpenVPN.

  If OpenVPN is run with the --management-query-passwords
  directive, it will query the management interface for RSA
  private key passwords and the --auth-user-pass
  username/password.

  When OpenVPN needs a password from the management interface,
  it will produce a real-time ">PASSWORD:" message.

  Example 1:

    >PASSWORD:Need 'Private Key' password

  OpenVPN is indicating that it needs a password of type
  "Private Key".

  The management client should respond to this query as follows:

    password "Private Key" foo

  Example 2:

    >PASSWORD:Need 'Auth' username/password

  OpenVPN needs a --auth-user-pass password.  The management
  client should respond:

    username "Auth" foo
    password "Auth" bar

  The username/password itself can be in quotes, and special
  characters such as double quote or backslash must be escaped,
  for example,

    password "Private Key" "foo\"bar"

  The escaping rules are the same as for the config file.
  See the "Command Parsing" section below for more info.

  The PASSWORD real-time message type can also be used to
  indicate password or other types of authentication failure:

  Example 3: The private key password is incorrect and OpenVPN
  is exiting:

    >PASSWORD:Verification Failed: 'Private Key'

  Example 4: The --auth-user-pass username/password failed,
  and OpenVPN is exiting:

    >PASSWORD:Verification Failed: 'Auth'

  Example 5: The --auth-user-pass username/password failed,
  and the server provided a custom client-reason-text string
  using the client-deny server-side management interface command.

    >PASSWORD:Verification Failed: 'custom server-generated string'

COMMAND -- forget-passwords
---------------------------

The forget-passwords command will cause the daemon to forget passwords
entered during the session.

Command example:

  forget-passwords -- forget passwords entered so far.

COMMAND -- signal
-----------------

The signal command will send a signal to the OpenVPN daemon.
The signal can be one of SIGHUP, SIGTERM, SIGUSR1, or SIGUSR2.

Command example:

  signal SIGUSR1 -- send a SIGUSR1 signal to daemon

COMMAND -- state
----------------

Show the current OpenVPN state, show state history, or
enable real-time notification of state changes.

These are the OpenVPN states:

CONNECTING    -- OpenVPN's initial state.
WAIT          -- (Client only) Waiting for initial response
                 from server.
AUTH          -- (Client only) Authenticating with server.
GET_CONFIG    -- (Client only) Downloading configuration options
                 from server.
ASSIGN_IP     -- Assigning IP address to virtual network
                 interface.
ADD_ROUTES    -- Adding routes to system.
CONNECTED     -- Initialization Sequence Completed.
RECONNECTING  -- A restart has occurred.
EXITING       -- A graceful exit is in progress.

Command examples:

  state        -- Print current OpenVPN state.
  state on     -- Enable real-time notification of state changes.
  state off    -- Disable real-time notification of state changes.
  state all    -- Print current state history.
  state 3      -- Print the 3 most recent state transitions.
  state on all -- Atomically show state history while at the
                  same time enable real-time state notification
		  of future state transitions.

The output format consists of 4 comma-separated parameters: 
  (a) the integer unix date/time,
  (b) the state name,
  (c) optional descriptive string (used mostly on RECONNECTING
      and EXITING to show the reason for the disconnect),
  (d) optional TUN/TAP local IP address (shown for ASSIGN_IP
      and CONNECTED), and
  (e) optional address of remote server (OpenVPN 2.1 or higher).

Real-time state notifications will have a ">STATE:" prefix
prepended to them.

COMMAND -- status
-----------------

Show current daemon status information, in the same format as
that produced by the OpenVPN --status directive.

Command examples:

status   -- Show status information using the default status
            format version.

status 3 -- Show status information using the format of
            --status-version 3.

COMMAND -- username
-------------------

See the "password" section above.

COMMAND -- verb
---------------

Change the OpenVPN --verb parameter.  The verb parameter
controls the output verbosity, and may range from 0 (no output)
to 15 (maximum output).  See the OpenVPN man page for additional
info on verbosity levels.

Command examples:

  verb 4  -- change the verb parameter to 4
  mute    -- show the current verb setting

COMMAND -- version
------------------

Show the current OpenVPN and Management Interface versions.


COMMAND -- auth-retry
---------------------

Set the --auth-retry setting to control how OpenVPN responds to
username/password authentication errors.  See the manual page
for more info.

Command examples:

  auth-retry interact -- Don't exit when bad username/passwords are entered.
                         Query for new input and retry.

COMMAND -- needok  (OpenVPN 2.1 or higher)
------------------------------------------

Confirm a ">NEED-OK" real-time notification, normally used by
OpenVPN to block while waiting for a specific user action.

Example:

  OpenVPN needs the user to insert a cryptographic token,
  so it sends a real-time notification:

    >NEED-OK:Need 'token-insertion-request' confirmation MSG:Please insert your cryptographic token

  The management client, if it is a GUI, can flash a dialog
  box containing the text after the "MSG:" marker to the user.
  When the user acknowledges the dialog box,
  the management client can issue this command:

     needok token-insertion-request ok
  or
     needok token-insertion-request cancel

COMMAND -- needstr  (OpenVPN 2.1 or higher)
-------------------------------------------

Confirm a ">NEED-STR" real-time notification, normally used by
OpenVPN to block while waiting for a specific user input.

Example:

  OpenVPN needs the user to specify some input, so it sends a
  real-time notification:

    >NEED-STR:Need 'name' input MSG:Please specify your name

  The management client, if it is a GUI, can flash a dialog
  box containing the text after the "MSG:" marker to the user.
  When the user acknowledges the dialog box,
  the management client can issue this command:

     needstr name "John"

COMMAND -- pkcs11-id-count  (OpenVPN 2.1 or higher)
---------------------------------------------------

Retrieve available number of certificates.

Example:

     pkcs11-id-count
     >PKCS11ID-COUNT:5

COMMAND -- pkcs11-id-get  (OpenVPN 2.1 or higher)
-------------------------------------------------

Retrieve certificate by index, the ID string should be provided
as PKCS#11 identity, the blob is BASE64 encoded certificate.

Example:

     pkcs11-id-get 1
     PKCS11ID-ENTRY:'1', ID:'<snip>', BLOB:'<snip>'

COMMAND -- client-auth  (OpenVPN 2.1 or higher)
-----------------------------------------------

Authorize a ">CLIENT:CONNECT" or ">CLIENT:REAUTH" request and specify
"client-connect" configuration directives in a subsequent text block.

The OpenVPN server should have been started with the
--management-client-auth directive so that it will ask the management
interface to approve client connections.


  client-auth {CID} {KID}
  line_1
  line_2
  ...
  line_n
  END

CID,KID -- client ID and Key ID.  See documentation for ">CLIENT:"
notification for more info.

line_1 to line_n -- client-connect configuration text block, as would be
returned by a --client-connect script.  The text block may be null, with
"END" immediately following the "client-auth" line (using a null text
block is equivalent to using the client-auth-nt command).

A client-connect configuration text block contains OpenVPN directives
that will be applied to the client instance object representing a newly
connected client.

COMMAND -- client-auth-nt  (OpenVPN 2.1 or higher)
--------------------------------------------------

Authorize a ">CLIENT:CONNECT" or ">CLIENT:REAUTH" request without specifying
client-connect configuration text.

The OpenVPN server should have been started with the
--management-client-auth directive so that it will ask the management
interface to approve client connections.

  client-auth-nt {CID} {KID}

CID,KID -- client ID and Key ID.  See documentation for ">CLIENT:"
notification for more info.

COMMAND -- client-deny  (OpenVPN 2.1 or higher)
-----------------------------------------------

Deny a ">CLIENT:CONNECT" or ">CLIENT:REAUTH" request.

  client-deny {CID} {KID} "reason-text" ["client-reason-text"]

CID,KID -- client ID and Key ID.  See documentation for ">CLIENT:"
notification for more info.

reason-text: a human-readable message explaining why the authentication
request was denied.  This message will be output to the OpenVPN log
file or syslog.

client-reason-text: a message that will be sent to the client as
part of the AUTH_FAILED message.

Note that client-deny denies a specific Key ID (pertaining to a
TLS renegotiation).  A client-deny command issued in response to
an initial TLS key negotiation (notified by ">CLIENT:CONNECT") will
terminate the client session after returning "AUTH-FAILED" to the client.
On the other hand, a client-deny command issued in response to
a TLS renegotiation (">CLIENT:REAUTH") will invalidate the renegotiated
key, however the TLS session associated with the currently active
key will continue to live for up to --tran-window seconds before
expiration.

To immediately kill a client session, use "client-kill".

COMMAND -- client-kill  (OpenVPN 2.1 or higher)
-----------------------------------------------

Immediately kill a client instance by CID.

  client-kill {CID}

CID -- client ID.  See documentation for ">CLIENT:" notification for more
info.

COMMAND -- client-pf  (OpenVPN 2.1 or higher)
---------------------------------------------

Push a packet filter file to a specific client.

The OpenVPN server should have been started with the
--management-client-pf directive so that it will require that
VPN tunnel packets sent or received by client instances must
conform to that client's packet filter configuration.

  client-pf {CID}
  line_1
  line_2
  ...
  line_n
  END

CID -- client ID.  See documentation for ">CLIENT:" notification for
more info.

line_1 to line_n -- the packet filter configuration file for this
client.

Packet filter file grammar:

 [CLIENTS DROP|ACCEPT]
 {+|-}common_name1
 {+|-}common_name2
 . . .
 [SUBNETS DROP|ACCEPT]
 {+|-}subnet1
 {+|-}subnet2
 . . .
 [END]

 Subnet: IP-ADDRESS | IP-ADDRESS/NUM_NETWORK_BITS | "unknown"

 CLIENTS refers to the set of clients (by their common-name) which
 this instance is allowed ('+') to connect to, or is excluded ('-')
 from connecting to.  Note that in the case of client-to-client
 connections, such communication must be allowed by the packet filter
 configuration files of both clients AND the --client-to-client
 directive must have been specified in the OpenVPN server config.

 SUBNETS refers to IP addresses or IP address subnets which this
 client instance may connect to ('+') or is excluded ('-') from
 connecting to, and applies to IPv4 and ARP packets.  The special
 "unknown" tag refers to packets of unknown type, i.e. a packet that
 is not IPv4 or ARP.

 DROP or ACCEPT defines default policy when there is no explicit match
 for a common-name or subnet.  The [END] tag must exist.

 Notes:

 * The SUBNETS section currently only supports IPv4 addresses and
   subnets.

 * A given client or subnet rule applies to both incoming and
   outgoing packets.

 * The CLIENTS list is order-invariant.  Because the list is stored
   as a hash-table, the order of the list does not affect its function.

 * The SUBNETS table is scanned sequentially, and the first item to
   match is chosen.  Therefore the SUBNETS table is NOT order-invariant.

 * No client-to-client communication is allowed unless the
   --client-to-client configuration directive is enabled AND
   the CLIENTS list of BOTH clients allows the communication.

Example packet filter spec, as transmitted to the management interface:

 client-pf 42
 [CLIENTS ACCEPT]
 -accounting
 -enigma
 [SUBNETS DROP]
 -10.46.79.9
 +10.0.0.0/8
 [END]
 END

The above example sets the packet filter policy for the client
identified by CID=42.  This client may connect to all other clients
except those having a common name of "accounting" or "enigma".
The client may only interact with external IP addresses in the
10.0.0.0/8 subnet, however access to 10.46.79.9 is specifically
excluded.

Another example packet filter spec, as transmitted to the
management interface:

 client-pf 99
 [CLIENTS DENY]
 +public
 [SUBNETS ACCEPT]
 +10.10.0.1
 -10.0.0.0/8
 -unknown
 [END]
 END

The above example sets the packet filter policy for the client
identified by CID=99.  This client may not connect to any other
clients except those having a common name of "public".  It may
interact with any external IP address except those in the
10.0.0.0/8 netblock.  However interaction with one address in
the 10.0.0.0/8 netblock is allowed: 10.10.0.1.  Also, the client
may not interact with external IP addresses using an "unknown"
protocol (i.e. one that is not IPv4 or ARP).

COMMAND -- remote  (OpenVPN AS 2.1.5/OpenVPN 2.3 or higher)
--------------------------------------------

Provide remote host/port in response to a >REMOTE notification
(client only).  Requires that the --management-query-remote
directive is used.

  remote ACTION [HOST PORT]

The "remote" command should only be given in response to a >REMOTE
notification.  For example, the following >REMOTE notification
indicates that the client config file would ordinarily connect
to vpn.example.com port 1194 (UDP):

  >REMOTE:vpn.example.com,1194,udp

Now, suppose we want to override the host and port, connecting
instead to vpn.otherexample.com port 1234.  After receiving
the above notification, use this command:

  remote MOD vpn.otherexample.com 1234

To accept the same host and port as the client would ordinarily
have connected to, use this command:

  remote ACCEPT

To skip the current connection entry and advance to the next one,
use this command:

  remote SKIP

COMMAND -- proxy  (OpenVPN 2.3 or higher)
--------------------------------------------

Provide proxy server host/port and flags in response to a >PROXY
notification (client only).  Requires that the --management-query-proxy
directive is used.

  proxy TYPE HOST PORT ["nct"]

The "proxy" command must only be given in response to a >PROXY
notification.  Use the "nct" flag if you only want to allow
non-cleartext auth with the proxy server.  The following >PROXY
notification indicates that the client config file would ordinarily
connect to the first --remote configured, vpn.example.com using TCP:

  >PROXY:1,TCP,vpn.example.com

Now, suppose we want to connect to the remote host using the proxy server
proxy.intranet port 8080 with secure authentication only, if required.
After receiving the above notification, use this command:

  proxy HTTP proxy.intranet 8080 nct

You can also use the SOCKS keyword to pass a SOCKS server address, like:

  proxy SOCKS fe00::1 1080

To accept connecting to the host and port directly, use this command:

  proxy NONE

COMMAND -- rsa-sig (OpenVPN 2.3 or higher)
------------------------------------------
Provides support for external storage of the private key. Requires the
--management-external-key option. This option can be used instead of "key"
in client mode, and allows the client to run without the need to load the
actual private key. When the SSL protocol needs to perform an RSA sign
operation, the data to be signed will be sent to the management interface
via a notification as follows:

>RSA_SIGN:[BASE64_DATA]

The management interface client should then sign BASE64_DATA
using the private key and return the SSL signature as follows:

rsa-sig
[BASE64_SIG_LINE]
.
.
.
END

Base64 encoded output of RSA_sign(NID_md5_sha1,... will provide a
correct signature.

This capability is intended to allow the use of arbitrary cryptographic
service providers with OpenVPN via the management interface.


OUTPUT FORMAT
-------------

(1) Command success/failure indicated by "SUCCESS: [text]" or
    "ERROR: [text]".

(2) For commands which print multiple lines of output,
    the last line will be "END".

(3) Real-time messages will be in the form ">[source]:[text]",
    where source is "CLIENT", "ECHO", "FATAL", "HOLD", "INFO", "LOG",
    "NEED-OK", "PASSWORD", or "STATE".

REAL-TIME MESSAGE FORMAT
------------------------

The OpenVPN management interface produces two kinds of
output: (a) output from a command, or (b) asynchronous,
real-time output which can be generated at any time.

Real-time messages start with a '>' character in the first
column and are immediately followed by a type keyword
indicating the type of real-time message.  The following
types are currently defined:

BYTECOUNT -- Real-time bandwidth usage notification, as enabled
             by "bytecount" command when OpenVPN is running as
             a client.

BYTECOUNT_CLI -- Real-time bandwidth usage notification per-client,
	         as enabled by "bytecount" command when OpenVPN is
                 running as a server.

CLIENT   -- Notification of client connections and disconnections
            on an OpenVPN server.  Enabled when OpenVPN is started
            with the --management-client-auth option.  CLIENT
            notifications may be multi-line.  See "The CLIENT
            notification" section below for detailed info.

ECHO     -- Echo messages as controlled by the "echo" command.

FATAL    -- A fatal error which is output to the log file just
            prior to OpenVPN exiting.

HOLD     -- Used to indicate that OpenVPN is in a holding state
            and will not start until it receives a
            "hold release" command.

INFO     -- Informational messages such as the welcome message.

LOG      -- Log message output as controlled by the "log" command.

NEED-OK  -- OpenVPN needs the end user to do something, such as
            insert a cryptographic token.  The "needok" command can
            be used to tell OpenVPN to continue.

NEED-STR -- OpenVPN needs information from end, such as
            a certificate to use.  The "needstr" command can
            be used to tell OpenVPN to continue.

PASSWORD -- Used to tell the management client that OpenVPN
            needs a password, also to indicate password
            verification failure.

STATE    -- Shows the current OpenVPN state, as controlled
            by the "state" command.

The CLIENT notification
-----------------------

The ">CLIENT:" notification is enabled by the --management-client-auth
OpenVPN configuration directive that gives the management interface client
the responsibility to authenticate OpenVPN clients after their client
certificate has been verified.  CLIENT notifications may be multi-line, and
the sequentiality of a given CLIENT notification, its associated environmental
variables, and the terminating ">CLIENT:ENV,END" line are guaranteed to be
atomic.

CLIENT notification types:

(1) Notify new client connection ("CONNECT") or existing client TLS session
    renegotiation ("REAUTH").  Information about the client is provided
    by a list of environmental variables which are documented in the OpenVPN
    man page.  The environmental variables passed are equivalent to those
    that would be passed to an --auth-user-pass-verify script.

    >CLIENT:CONNECT|REAUTH,{CID},{KID}
    >CLIENT:ENV,name1=val1
    >CLIENT:ENV,name2=val2
    >CLIENT:ENV,...
    >CLIENT:ENV,END

(2) Notify successful client authentication and session initiation.
    Called after CONNECT.

    >CLIENT:ESTABLISHED,{CID}
    >CLIENT:ENV,name1=val1
    >CLIENT:ENV,name2=val2
    >CLIENT:ENV,...
    >CLIENT:ENV,END

(3) Notify existing client disconnection.  The environmental variables passed
    are equivalent to those that would be passed to a --client-disconnect
    script.

    >CLIENT:DISCONNECT,{CID}
    >CLIENT:ENV,name1=val1
    >CLIENT:ENV,name2=val2
    >CLIENT:ENV,...
    >CLIENT:ENV,END

(4) Notify that a particular virtual address or subnet
    is now associated with a specific client.

    >CLIENT:ADDRESS,{CID},{ADDR},{PRI}

Variables:

CID --  Client ID, numerical ID for each connecting client, sequence = 0,1,2,...
KID --  Key ID, numerical ID for the key associated with a given client TLS session,
        sequence = 0,1,2,...
PRI --  Primary (1) or Secondary (0) VPN address/subnet.  All clients have at least
        one primary IP address.  Secondary address/subnets are associated with
        client-specific "iroute" directives.
ADDR -- IPv4 address/subnet in the form 1.2.3.4 or 1.2.3.0/255.255.255.0

In the unlikely scenario of an extremely long-running OpenVPN server,
CID and KID should be assumed to recycle to 0 after (2^32)-1, however this
recycling behavior is guaranteed to be collision-free.

Command Parsing
---------------

The management interface uses the same command line lexical analyzer
as is used by the OpenVPN config file parser.

Whitespace is a parameter separator.

Double quotation or single quotation characters ("", '') can be used
to enclose parameters containing whitespace.

Backslash-based shell escaping is performed, using the following
mappings, when not in single quotations:

\\       Maps to a single backslash character (\).
\"       Pass a literal doublequote character ("), don't
         interpret it as enclosing a parameter.
\[SPACE] Pass a literal space or tab character, don't
         interpret it as a parameter delimiter.

Challenge/Response Protocol
---------------------------

The OpenVPN Challenge/Response Protocol allows an OpenVPN server to
generate challenge questions that are shown to the user, and to see
the user's responses to those challenges.  Based on the responses, the
server can allow or deny access.

In this way, the OpenVPN Challenge/Response Protocol can be used
to implement multi-factor authentication.  Two different
variations on the challenge/response protocol are supported: the
"Dynamic" and "Static" protocols.

The basic idea of Challenge/Response is that the user must enter an
additional piece of information, in addition to the username and
password, to successfully authenticate.  Normally, this information
is used to prove that the user posesses a certain key-like device
such as cryptographic token or a particular mobile phone.

Dynamic protocol:

The OpenVPN dynamic challenge/response protocol works by returning
a specially formatted error message after initial successful
authentication.  This error message contains the challenge question,
and is formatted as such:

  CRV1:<flags>:<state_id>:<username_base64>:<challenge_text>

flags: a series of optional, comma-separated flags:
 E : echo the response when the user types it
 R : a response is required

state_id: an opaque string that should be returned to the server
 along with the response.

username_base64 : the username formatted as base64

challenge_text : the challenge text to be shown to the user

Example challenge:

  CRV1:R,E:Om01u7Fh4LrGBS7uh0SWmzwabUiGiW6l:Y3Ix:Please enter token PIN

After showing the challenge_text and getting a response from the user
(if R flag is specified), the client should submit the following
auth creds back to the OpenVPN server:

Username: [username decoded from username_base64]
Password: CRV1::<state_id>::<response_text>

Where state_id is taken from the challenge request and response_text
is what the user entered in response to the challenge_text.
If the R flag is not present, response_text may be the empty
string.

Example response (suppose the user enters "8675309" for the token PIN):

  Username: cr1 ("Y3Ix" base64 decoded)
  Password: CRV1::Om01u7Fh4LrGBS7uh0SWmzwabUiGiW6l::8675309

Static protocol:

The static protocol differs from the dynamic protocol in that the
challenge question and response field is given to the user in the
initial username/password dialog, and the username, password, and
response are delivered back to the server in a single transaction.

The "static-challenge" directive is used to give the challenge text
to OpenVPN and indicate whether or not the response should be echoed.

When the "static-challenge" directive is used, the management
interface will respond as such when credentials are needed:

  >PASSWORD:Need 'Auth' username/password SC:<ECHO>,<TEXT>

  ECHO: "1" if response should be echoed, "0" to not echo
  TEXT: challenge text that should be shown to the user to
      facilitate their response

For example:

  >PASSWORD:Need 'Auth' username/password SC:1,Please enter token PIN

The above notification indicates that OpenVPN needs a --auth-user-pass
password plus a response to a static challenge ("Please enter token PIN").
The "1" after the "SC:" indicates that the response should be echoed.

The management interface client in this case should add the static
challenge text to the auth dialog followed by a field for the user to
enter a response.  Then the client should pack the password and response
together into an encoded password:

  username "Auth" foo
  password "Auth" "SCRV1:<BASE64_PASSWORD>:<BASE64_RESPONSE>"

For example, if the user entered "bar" as the password and 8675309
as the PIN, the following management interface commands should be
issued:

  username "Auth" foo
  password "Auth" "SCRV1:Zm9v:ODY3NTMwOQ=="

Client-side support for challenge/response protocol:

Currently, the Access Server client and standalone OpenVPN
client support both static and dynamic challenge/response
protocols.  However, any OpenVPN client UI that drives OpenVPN
via the management interface needs to add explicit support
for the challenge/response protocol.