aboutsummaryrefslogtreecommitdiffstats
path: root/lib/ssh/doc/src/ssh.xml
blob: ddfb50ebd2983eb558cf8f807cd9675aed123f96 (plain) (blame)
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
<?xml version="1.0" encoding="iso-8859-1" ?>
<!DOCTYPE erlref SYSTEM "erlref.dtd">

<erlref>
  <header>
    <copyright>
      <year>2004</year><year>2013</year>
      <holder>Ericsson AB. All Rights Reserved.</holder>
    </copyright>
    <legalnotice>
      The contents of this file are subject to the Erlang Public License,
      Version 1.1, (the "License"); you may not use this file except in
      compliance with the License. You should have received a copy of the
      Erlang Public License along with this software. If not, it can be
      retrieved online at http://www.erlang.org/.

      Software distributed under the License is distributed on an "AS IS"
      basis, WITHOUT WARRANTY OF ANY KIND, either express or implied. See
      the License for the specific language governing rights and limitations
      under the License.

    </legalnotice>
    
    <title>ssh</title>
    <date>2007-10-06</date>
  </header>
  <module>ssh</module>
  <modulesummary>Main API of the SSH application</modulesummary>
  <description>
    <p>Interface module for the SSH application. </p>
  </description>

   <section>
    <title>SSH</title>

    <list type="bulleted">
      <item>SSH requires the crypto and public_key applications.</item>
      <item>Supported SSH version is 2.0 </item>
      <item>Supported MAC algorithms: hmac-sha1</item>
      <item>Supported encryption algorithms: aes128-cb and 3des-cbc</item>
    </list>
 
  </section>
  
  <section>
    <title>DATA TYPES </title>
    <p>Type definitions that are used more than once in
    this module and/or abstractions to indicate the intended use of the data
    type:</p>
    <p><c>boolean() = true | false </c></p>
    <p><c>string() = [byte()]</c></p>
    <p><c>ssh_daemon_ref() - opaque to the user
    returned by ssh:daemon/[1,2,3]</c></p>
    <p><c>ssh_connection_ref() - opaque to the user
    returned by ssh:connect/3</c></p>
    <p><c>ip_address() - {N1,N2,N3,N4} % IPv4 |
    {K1,K2,K3,K4,K5,K6,K7,K8} % IPv6</c></p>
    <p><c>subsystem_spec() = {subsystem_name(),
    {channel_callback(), channel_init_args()}} </c></p>
    <p><c>subsystem_name() = string() </c></p>
    <p><c>channel_callback() = atom() - Name of the erlang module
    implementing the subsystem using the ssh_channel behavior see</c>
    <seealso marker="ssh_channel">ssh_channel(3)</seealso></p>
    <p><c>channel_init_args() = list()</c></p>
 </section>

 <funcs>
   
   <func>
     <name>close(ConnectionRef) -> ok </name>
      <fsummary>Closes an SSH connection</fsummary>
      <type>
	<v>ConnectionRef = ssh_connection_ref()</v>
      </type>
      <desc><p>Closes an SSH connection.</p>
      </desc>
    </func>
    
    <func>
      <name>connect(Host, Port, Options) -> </name>
      <name>connect(Host, Port, Options, Timeout) -> {ok,
      ssh_connection_ref()} | {error, Reason}</name>
      <fsummary>Connect to an ssh server.</fsummary>
      <type>
        <v>Host = string()</v>
	<v>Port = integer()</v>
	<d>The default is <c><![CDATA[22]]></c>, the assigned well known port
	number for SSH.</d>
	<v>Options = [{Option, Value}]</v>
	<v>Timeout = infinity | integer(milliseconds)</v>
	<d>Negotiation timeout, for connection timeout use the option <c>{connect_timeout, timeout()}</c>.</d>
      </type>
      <desc>
	<p>Connects to an SSH server. No channel is started. This is done
	by calling
	<seealso marker="ssh_connection#session_channel/2">ssh_connection:session_channel/[2, 4]</seealso>.</p>
	<p>Options are:</p>
	<taglist>
          <tag><c><![CDATA[{user_dir, string()}]]></c></tag>
	  <item>
	    <p>Sets the user directory i.e. the directory containing
	    ssh configuration files for the user such as
	    <c><![CDATA[known_hosts]]></c>, <c><![CDATA[id_rsa,
	    id_dsa]]></c> and
	    <c><![CDATA[authorized_key]]></c>. Defaults to the
	    directory normally referred to as
	    <c><![CDATA[~/.ssh]]></c> </p>
	  </item>
	  <tag><c><![CDATA[{dsa_pass_phrase, string()}]]></c></tag>
	  <item>
	    <p>If the user dsa key is protected by a passphrase it can be
	    supplied with this option.
	    </p>
	  </item>
	  <tag><c><![CDATA[{rsa_pass_phrase, string()}]]></c></tag>
	  <item>
	    <p>If the user rsa key is protected by a passphrase it can be
	    supplied with this option.
	    </p>
	  </item>
          <tag><c><![CDATA[{silently_accept_hosts, boolean()}]]></c></tag>
	  <item>
	    <p>When true hosts are added to the
	    file <c><![CDATA[known_hosts]]></c> without asking the user.
	    Defaults to false.
	    </p>
	  </item>
	  <tag><c><![CDATA[{user_interaction, boolean()}]]></c></tag>
	  <item>
	    <p>If false disables the client to connect to the server
	    if any user interaction is needed such as accepting that
	    the server will be added to the <c>known_hosts</c> file or
	    supplying a password. Defaults to true.
	    Even if user interaction is allowed it can be
	    suppressed by other options such as silently_accept_hosts and
	    password. Do note that it may not always be desirable to use
	    those options from a security point of view.</p>
	  </item>
	  <tag><c><![CDATA[{public_key_alg, 'ssh-rsa' | 'ssh-dss'}]]></c></tag>
	  <item>
            <p>Sets the preferred public key algorithm to use for user
	    authentication. If the the preferred algorithm fails for
	    some reason, the other algorithm is tried. The  default is
	    to try <c><![CDATA['ssh-rsa']]></c> first.</p>
	  </item>
	  <tag><c><![CDATA[{pref_public_key_algs, list()}]]></c></tag>
	  <item>
            <p>List of public key algorithms to try to use, 'ssh-rsa' and 'ssh-dss' available. 
	    Will override <c><![CDATA[{public_key_alg, 'ssh-rsa' | 'ssh-dss'}]]></c></p>
	  </item>
	  <tag><c><![CDATA[{connect_timeout, timeout()}]]></c></tag>
	  <item>
	    <p>Sets a timeout on the transport layer
	    connection. Defaults to <c>infinity</c>.</p>
	  </item>
	  <tag><c><![CDATA[{user, string()}]]></c></tag>
          <item>
	    <p>Provides a user name. If this option is not given, ssh
	    reads from the environment (<c><![CDATA[LOGNAME]]></c> or
	    <c><![CDATA[USER]]></c> on unix,
	    <c><![CDATA[USERNAME]]></c> on Windows).</p>
          </item>
	  <tag><c><![CDATA[{password, string()}]]></c></tag>
          <item>
	    <p>Provide a password for password authentication.  If
	    this option is not given, the user will be asked for a
	    password if the password authentication method is
	    attempted.</p>
          </item>
	  <tag><c><![CDATA[{key_cb, atom()}]]></c></tag>
	  <item>
	    <p>Module implementing the behaviour <seealso marker="ssh_client_key_api">ssh_client_key_api</seealso>.
	    Can be used to customize the handling of public keys.
	    </p>
	  </item>
	  <tag><c><![CDATA[{quiet_mode, atom() = boolean()}]]></c></tag>
	  <item>
	    <p>If true, the client will not print out anything on authorization.</p>
	  </item>
	  <tag><c><![CDATA[{fd, file_descriptor()}]]></c></tag>
	  <item>
	    <p>Allow an existing file descriptor to be used
	  (simply passed on to the transport protocol).</p></item>
	  <tag><c><![CDATA[{ipv6_disabled, boolean()}]]></c></tag>
	  <item>
	    <p>Determines if SSH shall use IPv6 or not.</p>
	  </item>
	  <tag><c><![CDATA[{rekey_limit, integer()}]]></c></tag>
	  <item>
	    <p>Provide, in bytes, when rekeying should be initiated, 
	    defaults to one time each GB and one time per hour.</p>
	  </item>
	  <tag><c><![CDATA[{idle_time, integer()}]]></c></tag>
	  <item>
 	  <p>Sets a timeout on connection when no channels are active, default is infinity</p></item>
	</taglist>
      </desc>   
    </func>

    <func>
      <name>connection_info(ConnectionRef, [Option]) ->[{Option,
      Value}] </name>
      <fsummary> Retrieves information about a connection. </fsummary>
      <type>
        <v>Option = client_version | server_version | peer</v>
	<v>Value = term() </v>
      </type>
      <desc>
        <p> Retrieves information about a connection. 
	</p>
      </desc>
    </func>
    
    <func>
      <name>daemon(Port) -> </name>
      <name>daemon(Port, Options) -> </name>
      <name>daemon(HostAddress, Port, Options) -> {ok,
      ssh_daemon_ref()} | {error, atom()}</name>
      <fsummary>Starts a server listening for SSH connections 
      on the given port.</fsummary>
      <type>
        <v>Port = integer()</v>
	<v>HostAddress = ip_address() | any</v>
	<v>Options = [{Option, Value}]</v>
        <v>Option = atom()</v>
	<v>Value = term()</v>
      </type>
      <desc>
        <p>Starts a server listening for SSH connections on the given
        port.</p>
	<p>Options are:</p>
        <taglist>
	  <tag><c><![CDATA[{subsystems, [subsystem_spec()]]]></c></tag>
	  <item>
	    Provides specifications for handling of subsystems. The
	    "sftp" subsystem spec can be retrieved by calling
	    ssh_sftpd:subsystem_spec/1. If the subsystems option in
	    not present the value of
	    <c>[ssh_sftpd:subsystem_spec([])]</c> will be used.  It is
	    of course possible to set the option to the empty list if
	    you do not want the daemon to run any subsystems at all.
	  </item>
	  <tag><c><![CDATA[{shell, {Module, Function, Args} |
	  fun(string() = User) - > pid() | fun(string() = User,
	  ip_address() = PeerAddr) -> pid()}]]></c></tag>
	  <item>
	    Defines the read-eval-print loop used when a shell is
	    requested by the client. Default is to use the erlang shell:
	    <c><![CDATA[{shell, start, []}]]></c>
	  </item>
	  <tag><c><![CDATA[{ssh_cli, {channel_callback(),
	  channel_init_args()}}]]></c></tag>
	  <item>
	    Provides your own cli implementation, i.e. a channel callback
	    module that implements a shell and command execution. Note
	    that you may customize the shell read-eval-print loop using the
	    option <c>shell</c> which is much less work than implementing
	    your own cli channel.
	  </item>
	  <tag><c><![CDATA[{user_dir, String}]]></c></tag>
	  <item>
	    <p>Sets the user directory i.e. the directory containing
	    ssh configuration files for the user such as
	    <c><![CDATA[known_hosts]]></c>, <c><![CDATA[id_rsa,
	    id_dsa]]></c> and
	    <c><![CDATA[authorized_key]]></c>. Defaults to the
	    directory normally referred to as
	    <c><![CDATA[~/.ssh]]></c> </p>
	  </item>
          <tag><c><![CDATA[{system_dir, string()}]]></c></tag>
          <item>
            <p>Sets the system directory, containing the host key files
            that identifies the host keys for ssh. The default is
            <c><![CDATA[/etc/ssh]]></c>, note that for security reasons
            this directory is normally only accessible by the root user.</p>
	  </item>
	  <tag><c><![CDATA[{auth_methods, string()}]]></c></tag>
	  <item>
	    <p>Comma separated string that determines which
	    authentication methodes that the server should support and
	    in what order they will be tried. Defaults to
	    <c><![CDATA["publickey,keyboard-interactive,password"]]></c></p>
          </item>
	  <tag><c><![CDATA[{user_passwords, [{string() = User,
	  string() = Password}]}]]></c></tag>
	  <item>
            <p>Provide passwords for password authentication.They will
	    be used when someone tries to connect to the server and
	    public key user authentication fails. The option provides
	    a list of valid user names and the corresponding password.
	    </p>
          </item>
          <tag><c><![CDATA[{password, string()}]]></c></tag>
          <item>
            <p>Provide a global password that will authenticate any
              user. From a security perspective this option makes
	      the server very vulnerable.</p>
	  </item>
	  <tag><c><![CDATA[{pwdfun, fun(User::string(), password::string() -> boolean()}]]></c></tag>
	  <item>
	    <p>Provide a function for password validation. This is called
	      with user and password as strings, and should return
	      <c><![CDATA[true]]></c> if the password is valid and
	      <c><![CDATA[false]]></c> otherwise.</p>
	  </item>
	  <tag><c><![CDATA[{key_cb, atom()}]]></c></tag>
	  <item>
	    <p>Module implementing the behaviour <seealso marker="ssh_server_key_api">ssh_server_key_api</seealso>.
	    Can be used to customize the handling of public keys.
	    </p>
	  </item>
	  <tag><c><![CDATA[{fd, file_descriptor()}]]></c></tag>
	  <item>
	    <p>Allow an existing file-descriptor to be used
	  (simply passed on to the transport protocol).</p></item>
	  <tag><c><![CDATA[{ip_v6_disabled, boolean()}]]></c></tag>
	  <item>
	    <p>Determines if SSH shall use IPv6 or not (only used when 
               HostAddress is set to any).</p></item>
	  <tag><c><![CDATA[{failfun, fun()}]]></c></tag>
	  <item>
	    <p>Provide a fun() to implement your own logging when a user fails to authenticate.</p>
	  </item>
	  <tag><c><![CDATA[{connectfun, fun()}]]></c></tag>
	  <item>
	    <p>Provide a fun() to implement your own logging when a user authenticates to the server.</p>
	  </item>
	  <tag><c><![CDATA[{disconnectfun, fun()}]]></c></tag>
	  <item>
	    <p>Provide a fun() to implement your own logging when a user disconnects from the server.</p>
	  </item>
        </taglist>
      </desc>
    </func>

    <func>
      <name>peername(ConnectionRef) -> {ok, {Address,Port}} | {error,Error} </name>
      <fsummary> </fsummary>
      <type>
	<v> ConnectionRef = ssh_connection_ref()</v>
        <v> Address = ip_address()</v>
	<v> Port = integer()</v>
      </type>
      <desc>
        <p>Returns the address and port for the other end of a connection.
	</p>
      </desc>
    </func>

    <func>
      <name>shell(Host) -> </name>
      <name>shell(Host, Option) -> </name>
      <name>shell(Host, Port, Option) -> _</name>
      <fsummary> </fsummary>
      <type>
        <v> Host = string()</v>
	<v> Port = integer()</v>
	<v> Options - see ssh:connect/3</v>
      </type>
      <desc>
        <p>Starts an interactive shell via an SSH server on the
	given <c>Host</c>. The function waits for user input,
	and will not return until the remote shell is ended (i.e.
	exit from the shell).
	</p>
      </desc>
    </func>

    <func>
      <name>start() -> </name>
      <name>start(Type) -> ok | {error, Reason}</name>
      <fsummary>Starts the SSH application. </fsummary>
      <type>
        <v>Type =  permanent | transient | temporary</v>
	<v>Reason = term() </v>
      </type>
      <desc>
        <p>Utility function that starts crypto, public_key and the SSH
	application. Defult type is temporary.
	See also <seealso marker="kernel:application">application(3)</seealso>
	</p>
      </desc>
    </func>

    <func>
      <name>stop() -> ok </name>
      <fsummary>Stops the SSH application.</fsummary>
      <desc>
        <p>Stops the SSH application. See also
          <seealso marker="kernel:application">application(3)</seealso></p>
      </desc>
    </func>
    
    <func>
      <name>stop_daemon(DaemonRef) -> </name>
      <name>stop_daemon(Address, Port) -> ok </name>
      <fsummary>Stops the listener and all connections started by 
      the listener.</fsummary>
      <type>
	<v>DaemonRef = ssh_daemon_ref()</v>
	<v>Address = ip_address()</v>
	<v>Port = integer()</v>
      </type>
      <desc>
	<p>Stops the listener and all connections started by 
	the listener.</p>
      </desc>
    </func>

    <func>
      <name>stop_listener(DaemonRef) -> </name>
      <name>stop_listener(Address, Port) -> ok </name>
      <fsummary>Stops the listener, but leaves existing connections started
	by the listener up and running.</fsummary>
      <type>
	<v>DaemonRef = ssh_daemon_ref()</v>
        <v>Address = ip_address()</v>
	<v>Port = integer()</v>
      </type>
      <desc>
	<p>Stops the listener, but leaves existing connections started
	by the listener up and running.</p>
      </desc>
    </func>

  </funcs>
  
</erlref>