]>
Commit | Line | Data |
---|---|---|
c9f39d2c | 1 | .\" $OpenBSD: ssh-keygen.1,v 1.63 2004/08/13 00:01:43 jmc Exp $ |
3c0ef626 | 2 | .\" |
3 | .\" -*- nroff -*- | |
4 | .\" | |
5 | .\" Author: Tatu Ylonen <ylo@cs.hut.fi> | |
6 | .\" Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland | |
7 | .\" All rights reserved | |
8 | .\" | |
9 | .\" As far as I am concerned, the code I have written for this software | |
10 | .\" can be used freely for any purpose. Any derived versions of this | |
11 | .\" software must be clearly marked as such, and if the derived work is | |
12 | .\" incompatible with the protocol description in the RFC file, it must be | |
13 | .\" called by a name other than "ssh" or "Secure Shell". | |
14 | .\" | |
15 | .\" | |
16 | .\" Copyright (c) 1999,2000 Markus Friedl. All rights reserved. | |
17 | .\" Copyright (c) 1999 Aaron Campbell. All rights reserved. | |
18 | .\" Copyright (c) 1999 Theo de Raadt. All rights reserved. | |
19 | .\" | |
20 | .\" Redistribution and use in source and binary forms, with or without | |
21 | .\" modification, are permitted provided that the following conditions | |
22 | .\" are met: | |
23 | .\" 1. Redistributions of source code must retain the above copyright | |
24 | .\" notice, this list of conditions and the following disclaimer. | |
25 | .\" 2. Redistributions in binary form must reproduce the above copyright | |
26 | .\" notice, this list of conditions and the following disclaimer in the | |
27 | .\" documentation and/or other materials provided with the distribution. | |
28 | .\" | |
29 | .\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR | |
30 | .\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES | |
31 | .\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. | |
32 | .\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, | |
33 | .\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT | |
34 | .\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, | |
35 | .\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY | |
36 | .\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT | |
37 | .\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF | |
38 | .\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. | |
39 | .\" | |
40 | .Dd September 25, 1999 | |
41 | .Dt SSH-KEYGEN 1 | |
42 | .Os | |
43 | .Sh NAME | |
44 | .Nm ssh-keygen | |
45 | .Nd authentication key generation, management and conversion | |
46 | .Sh SYNOPSIS | |
47 | .Nm ssh-keygen | |
6a9b3198 | 48 | .Bk -words |
3c0ef626 | 49 | .Op Fl q |
50 | .Op Fl b Ar bits | |
e9a17296 | 51 | .Fl t Ar type |
3c0ef626 | 52 | .Op Fl N Ar new_passphrase |
53 | .Op Fl C Ar comment | |
54 | .Op Fl f Ar output_keyfile | |
6a9b3198 | 55 | .Ek |
3c0ef626 | 56 | .Nm ssh-keygen |
57 | .Fl p | |
58 | .Op Fl P Ar old_passphrase | |
59 | .Op Fl N Ar new_passphrase | |
60 | .Op Fl f Ar keyfile | |
61 | .Nm ssh-keygen | |
62 | .Fl i | |
63 | .Op Fl f Ar input_keyfile | |
64 | .Nm ssh-keygen | |
65 | .Fl e | |
66 | .Op Fl f Ar input_keyfile | |
67 | .Nm ssh-keygen | |
68 | .Fl y | |
69 | .Op Fl f Ar input_keyfile | |
70 | .Nm ssh-keygen | |
71 | .Fl c | |
72 | .Op Fl P Ar passphrase | |
73 | .Op Fl C Ar comment | |
74 | .Op Fl f Ar keyfile | |
75 | .Nm ssh-keygen | |
76 | .Fl l | |
77 | .Op Fl f Ar input_keyfile | |
78 | .Nm ssh-keygen | |
79 | .Fl B | |
80 | .Op Fl f Ar input_keyfile | |
81 | .Nm ssh-keygen | |
82 | .Fl D Ar reader | |
83 | .Nm ssh-keygen | |
84 | .Fl U Ar reader | |
85 | .Op Fl f Ar input_keyfile | |
0fff78ff | 86 | .Nm ssh-keygen |
87 | .Fl r Ar hostname | |
88 | .Op Fl f Ar input_keyfile | |
89 | .Op Fl g | |
90 | .Nm ssh-keygen | |
91 | .Fl G Ar output_file | |
cdd66111 | 92 | .Op Fl v |
0fff78ff | 93 | .Op Fl b Ar bits |
94 | .Op Fl M Ar memory | |
95 | .Op Fl S Ar start_point | |
96 | .Nm ssh-keygen | |
97 | .Fl T Ar output_file | |
98 | .Fl f Ar input_file | |
cdd66111 | 99 | .Op Fl v |
0fff78ff | 100 | .Op Fl a Ar num_trials |
101 | .Op Fl W Ar generator | |
3c0ef626 | 102 | .Sh DESCRIPTION |
103 | .Nm | |
104 | generates, manages and converts authentication keys for | |
105 | .Xr ssh 1 . | |
106 | .Nm | |
f5799ae1 | 107 | can create RSA keys for use by SSH protocol version 1 and RSA or DSA |
0fff78ff | 108 | keys for use by SSH protocol version 2. |
109 | The type of key to be generated is specified with the | |
3c0ef626 | 110 | .Fl t |
e9a17296 | 111 | option. |
3c0ef626 | 112 | .Pp |
0fff78ff | 113 | .Nm |
114 | is also used to generate groups for use in Diffie-Hellman group | |
115 | exchange (DH-GEX). | |
116 | See the | |
117 | .Sx MODULI GENERATION | |
118 | section for details. | |
119 | .Pp | |
3c0ef626 | 120 | Normally each user wishing to use SSH |
121 | with RSA or DSA authentication runs this once to create the authentication | |
122 | key in | |
123 | .Pa $HOME/.ssh/identity , | |
124 | .Pa $HOME/.ssh/id_dsa | |
125 | or | |
126 | .Pa $HOME/.ssh/id_rsa . | |
127 | Additionally, the system administrator may use this to generate host keys, | |
128 | as seen in | |
129 | .Pa /etc/rc . | |
130 | .Pp | |
131 | Normally this program generates the key and asks for a file in which | |
132 | to store the private key. | |
133 | The public key is stored in a file with the same name but | |
134 | .Dq .pub | |
135 | appended. | |
136 | The program also asks for a passphrase. | |
137 | The passphrase may be empty to indicate no passphrase | |
138 | (host keys must have an empty passphrase), or it may be a string of | |
139 | arbitrary length. | |
e9a17296 | 140 | A passphrase is similar to a password, except it can be a phrase with a |
141 | series of words, punctuation, numbers, whitespace, or any string of | |
142 | characters you want. | |
143 | Good passphrases are 10-30 characters long, are | |
3c0ef626 | 144 | not simple sentences or otherwise easily guessable (English |
145 | prose has only 1-2 bits of entropy per character, and provides very bad | |
e9a17296 | 146 | passphrases), and contain a mix of upper and lowercase letters, |
147 | numbers, and non-alphanumeric characters. | |
3c0ef626 | 148 | The passphrase can be changed later by using the |
149 | .Fl p | |
150 | option. | |
151 | .Pp | |
152 | There is no way to recover a lost passphrase. | |
153 | If the passphrase is | |
154 | lost or forgotten, a new key must be generated and copied to the | |
155 | corresponding public key to other machines. | |
156 | .Pp | |
157 | For RSA1 keys, | |
158 | there is also a comment field in the key file that is only for | |
159 | convenience to the user to help identify the key. | |
160 | The comment can tell what the key is for, or whatever is useful. | |
161 | The comment is initialized to | |
162 | .Dq user@host | |
163 | when the key is created, but can be changed using the | |
164 | .Fl c | |
165 | option. | |
166 | .Pp | |
167 | After a key is generated, instructions below detail where the keys | |
168 | should be placed to be activated. | |
169 | .Pp | |
170 | The options are as follows: | |
171 | .Bl -tag -width Ds | |
0fff78ff | 172 | .It Fl a Ar trials |
173 | Specifies the number of primality tests to perform when screening DH-GEX | |
174 | candidates using the | |
175 | .Fl T | |
176 | command. | |
3c0ef626 | 177 | .It Fl b Ar bits |
178 | Specifies the number of bits in the key to create. | |
179 | Minimum is 512 bits. | |
6a9b3198 | 180 | Generally, 1024 bits is considered sufficient. |
3c0ef626 | 181 | The default is 1024 bits. |
182 | .It Fl c | |
183 | Requests changing the comment in the private and public key files. | |
184 | This operation is only supported for RSA1 keys. | |
185 | The program will prompt for the file containing the private keys, for | |
186 | the passphrase if the key has one, and for the new comment. | |
187 | .It Fl e | |
188 | This option will read a private or public OpenSSH key file and | |
189 | print the key in a | |
190 | .Sq SECSH Public Key File Format | |
191 | to stdout. | |
192 | This option allows exporting keys for use by several commercial | |
193 | SSH implementations. | |
0fff78ff | 194 | .It Fl g |
c9f39d2c | 195 | Use generic DNS format when printing fingerprint resource records using the |
196 | .Fl r | |
197 | command. | |
3c0ef626 | 198 | .It Fl f Ar filename |
199 | Specifies the filename of the key file. | |
200 | .It Fl i | |
201 | This option will read an unencrypted private (or public) key file | |
202 | in SSH2-compatible format and print an OpenSSH compatible private | |
203 | (or public) key to stdout. | |
204 | .Nm | |
205 | also reads the | |
206 | .Sq SECSH Public Key File Format . | |
207 | This option allows importing keys from several commercial | |
208 | SSH implementations. | |
209 | .It Fl l | |
210 | Show fingerprint of specified public key file. | |
211 | Private RSA1 keys are also supported. | |
212 | For RSA and DSA keys | |
213 | .Nm | |
214 | tries to find the matching public key file and prints its fingerprint. | |
215 | .It Fl p | |
216 | Requests changing the passphrase of a private key file instead of | |
217 | creating a new private key. | |
218 | The program will prompt for the file | |
219 | containing the private key, for the old passphrase, and twice for the | |
220 | new passphrase. | |
221 | .It Fl q | |
222 | Silence | |
223 | .Nm ssh-keygen . | |
224 | Used by | |
225 | .Pa /etc/rc | |
226 | when creating a new key. | |
227 | .It Fl y | |
228 | This option will read a private | |
229 | OpenSSH format file and print an OpenSSH public key to stdout. | |
230 | .It Fl t Ar type | |
231 | Specifies the type of the key to create. | |
232 | The possible values are | |
233 | .Dq rsa1 | |
234 | for protocol version 1 and | |
235 | .Dq rsa | |
236 | or | |
237 | .Dq dsa | |
238 | for protocol version 2. | |
3c0ef626 | 239 | .It Fl B |
240 | Show the bubblebabble digest of specified private or public key file. | |
241 | .It Fl C Ar comment | |
242 | Provides the new comment. | |
243 | .It Fl D Ar reader | |
244 | Download the RSA public key stored in the smartcard in | |
245 | .Ar reader . | |
0fff78ff | 246 | .It Fl G Ar output_file |
247 | Generate candidate primes for DH-GEX. | |
248 | These primes must be screened for | |
249 | safety (using the | |
250 | .Fl T | |
251 | option) before use. | |
252 | .It Fl M Ar memory | |
253 | Specify the amount of memory to use (in megabytes) when generating | |
254 | candidate moduli for DH-GEX. | |
3c0ef626 | 255 | .It Fl N Ar new_passphrase |
256 | Provides the new passphrase. | |
257 | .It Fl P Ar passphrase | |
258 | Provides the (old) passphrase. | |
0fff78ff | 259 | .It Fl S Ar start |
260 | Specify start point (in hex) when generating candidate moduli for DH-GEX. | |
261 | .It Fl T Ar output_file | |
262 | Test DH group exchange candidate primes (generated using the | |
263 | .Fl G | |
264 | option) for safety. | |
265 | .It Fl W Ar generator | |
266 | Specify desired generator when testing candidate moduli for DH-GEX. | |
3c0ef626 | 267 | .It Fl U Ar reader |
268 | Upload an existing RSA private key into the smartcard in | |
269 | .Ar reader . | |
cdd66111 | 270 | .It Fl v |
271 | Verbose mode. | |
272 | Causes | |
273 | .Nm | |
274 | to print debugging messages about its progress. | |
275 | This is helpful for debugging moduli generation. | |
276 | Multiple | |
277 | .Fl v | |
278 | options increase the verbosity. | |
279 | The maximum is 3. | |
0fff78ff | 280 | .It Fl r Ar hostname |
c9f39d2c | 281 | Print the SSHFP fingerprint resource record named |
282 | .Ar hostname | |
283 | for the specified public key file. | |
3c0ef626 | 284 | .El |
0fff78ff | 285 | .Sh MODULI GENERATION |
286 | .Nm | |
287 | may be used to generate groups for the Diffie-Hellman Group Exchange | |
288 | (DH-GEX) protocol. | |
289 | Generating these groups is a two-step process: first, candidate | |
290 | primes are generated using a fast, but memory intensive process. | |
291 | These candidate primes are then tested for suitability (a CPU-intensive | |
292 | process). | |
293 | .Pp | |
294 | Generation of primes is performed using the | |
295 | .Fl G | |
296 | option. | |
297 | The desired length of the primes may be specified by the | |
298 | .Fl b | |
299 | option. | |
300 | For example: | |
301 | .Pp | |
302 | .Dl ssh-keygen -G moduli-2048.candidates -b 2048 | |
303 | .Pp | |
304 | By default, the search for primes begins at a random point in the | |
305 | desired length range. | |
306 | This may be overridden using the | |
307 | .Fl S | |
308 | option, which specifies a different start point (in hex). | |
309 | .Pp | |
310 | Once a set of candidates have been generated, they must be tested for | |
311 | suitability. | |
312 | This may be performed using the | |
313 | .Fl T | |
314 | option. | |
315 | In this mode | |
316 | .Nm | |
317 | will read candidates from standard input (or a file specified using the | |
318 | .Fl f | |
319 | option). | |
320 | For example: | |
321 | .Pp | |
322 | .Dl ssh-keygen -T moduli-2048 -f moduli-2048.candidates | |
323 | .Pp | |
324 | By default, each candidate will be subjected to 100 primality tests. | |
325 | This may be overridden using the | |
326 | .Fl a | |
327 | option. | |
328 | The DH generator value will be chosen automatically for the | |
329 | prime under consideration. | |
330 | If a specific generator is desired, it may be requested using the | |
331 | .Fl W | |
332 | option. | |
333 | Valid generator values are 2, 3 and 5. | |
334 | .Pp | |
335 | Screened DH groups may be installed in | |
336 | .Pa /etc/moduli . | |
337 | It is important that this file contains moduli of a range of bit lengths and | |
338 | that both ends of a connection share common moduli. | |
3c0ef626 | 339 | .Sh FILES |
340 | .Bl -tag -width Ds | |
341 | .It Pa $HOME/.ssh/identity | |
342 | Contains the protocol version 1 RSA authentication identity of the user. | |
343 | This file should not be readable by anyone but the user. | |
344 | It is possible to | |
345 | specify a passphrase when generating the key; that passphrase will be | |
346 | used to encrypt the private part of this file using 3DES. | |
347 | This file is not automatically accessed by | |
348 | .Nm | |
349 | but it is offered as the default file for the private key. | |
350 | .Xr ssh 1 | |
351 | will read this file when a login attempt is made. | |
352 | .It Pa $HOME/.ssh/identity.pub | |
353 | Contains the protocol version 1 RSA public key for authentication. | |
354 | The contents of this file should be added to | |
355 | .Pa $HOME/.ssh/authorized_keys | |
356 | on all machines | |
357 | where the user wishes to log in using RSA authentication. | |
358 | There is no need to keep the contents of this file secret. | |
359 | .It Pa $HOME/.ssh/id_dsa | |
360 | Contains the protocol version 2 DSA authentication identity of the user. | |
361 | This file should not be readable by anyone but the user. | |
362 | It is possible to | |
363 | specify a passphrase when generating the key; that passphrase will be | |
364 | used to encrypt the private part of this file using 3DES. | |
365 | This file is not automatically accessed by | |
366 | .Nm | |
367 | but it is offered as the default file for the private key. | |
368 | .Xr ssh 1 | |
369 | will read this file when a login attempt is made. | |
370 | .It Pa $HOME/.ssh/id_dsa.pub | |
371 | Contains the protocol version 2 DSA public key for authentication. | |
372 | The contents of this file should be added to | |
373 | .Pa $HOME/.ssh/authorized_keys | |
374 | on all machines | |
375 | where the user wishes to log in using public key authentication. | |
376 | There is no need to keep the contents of this file secret. | |
377 | .It Pa $HOME/.ssh/id_rsa | |
378 | Contains the protocol version 2 RSA authentication identity of the user. | |
379 | This file should not be readable by anyone but the user. | |
380 | It is possible to | |
381 | specify a passphrase when generating the key; that passphrase will be | |
382 | used to encrypt the private part of this file using 3DES. | |
383 | This file is not automatically accessed by | |
384 | .Nm | |
385 | but it is offered as the default file for the private key. | |
386 | .Xr ssh 1 | |
387 | will read this file when a login attempt is made. | |
388 | .It Pa $HOME/.ssh/id_rsa.pub | |
389 | Contains the protocol version 2 RSA public key for authentication. | |
390 | The contents of this file should be added to | |
391 | .Pa $HOME/.ssh/authorized_keys | |
392 | on all machines | |
393 | where the user wishes to log in using public key authentication. | |
394 | There is no need to keep the contents of this file secret. | |
0fff78ff | 395 | .It Pa /etc/moduli |
396 | Contains Diffie-Hellman groups used for DH-GEX. | |
397 | The file format is described in | |
398 | .Xr moduli 5 . | |
3c0ef626 | 399 | .El |
3c0ef626 | 400 | .Sh SEE ALSO |
401 | .Xr ssh 1 , | |
402 | .Xr ssh-add 1 , | |
403 | .Xr ssh-agent 1 , | |
0fff78ff | 404 | .Xr moduli 5 , |
3c0ef626 | 405 | .Xr sshd 8 |
406 | .Rs | |
407 | .%A J. Galbraith | |
408 | .%A R. Thayer | |
409 | .%T "SECSH Public Key File Format" | |
410 | .%N draft-ietf-secsh-publickeyfile-01.txt | |
411 | .%D March 2001 | |
412 | .%O work in progress material | |
413 | .Re | |
0fff78ff | 414 | .Sh AUTHORS |
415 | OpenSSH is a derivative of the original and free | |
416 | ssh 1.2.12 release by Tatu Ylonen. | |
417 | Aaron Campbell, Bob Beck, Markus Friedl, Niels Provos, | |
418 | Theo de Raadt and Dug Song | |
419 | removed many bugs, re-added newer features and | |
420 | created OpenSSH. | |
421 | Markus Friedl contributed the support for SSH | |
422 | protocol versions 1.5 and 2.0. |