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3c0ef626 | 1 | .\" $OpenBSD: ssh-keygen.1,v 1.50 2001/10/25 21:14:32 markus Exp $ |
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 | |
48 | .Op Fl q | |
49 | .Op Fl b Ar bits | |
50 | .Op Fl t Ar type | |
51 | .Op Fl N Ar new_passphrase | |
52 | .Op Fl C Ar comment | |
53 | .Op Fl f Ar output_keyfile | |
54 | .Nm ssh-keygen | |
55 | .Fl p | |
56 | .Op Fl P Ar old_passphrase | |
57 | .Op Fl N Ar new_passphrase | |
58 | .Op Fl f Ar keyfile | |
59 | .Nm ssh-keygen | |
60 | .Fl i | |
61 | .Op Fl f Ar input_keyfile | |
62 | .Nm ssh-keygen | |
63 | .Fl e | |
64 | .Op Fl f Ar input_keyfile | |
65 | .Nm ssh-keygen | |
66 | .Fl y | |
67 | .Op Fl f Ar input_keyfile | |
68 | .Nm ssh-keygen | |
69 | .Fl c | |
70 | .Op Fl P Ar passphrase | |
71 | .Op Fl C Ar comment | |
72 | .Op Fl f Ar keyfile | |
73 | .Nm ssh-keygen | |
74 | .Fl l | |
75 | .Op Fl f Ar input_keyfile | |
76 | .Nm ssh-keygen | |
77 | .Fl B | |
78 | .Op Fl f Ar input_keyfile | |
79 | .Nm ssh-keygen | |
80 | .Fl D Ar reader | |
81 | .Nm ssh-keygen | |
82 | .Fl U Ar reader | |
83 | .Op Fl f Ar input_keyfile | |
84 | .Sh DESCRIPTION | |
85 | .Nm | |
86 | generates, manages and converts authentication keys for | |
87 | .Xr ssh 1 . | |
88 | .Nm | |
89 | defaults to generating a RSA1 key for use by SSH protocol version 1. | |
90 | Specifying the | |
91 | .Fl t | |
92 | option instead creates a key for use by SSH protocol version 2. | |
93 | .Pp | |
94 | Normally each user wishing to use SSH | |
95 | with RSA or DSA authentication runs this once to create the authentication | |
96 | key in | |
97 | .Pa $HOME/.ssh/identity , | |
98 | .Pa $HOME/.ssh/id_dsa | |
99 | or | |
100 | .Pa $HOME/.ssh/id_rsa . | |
101 | Additionally, the system administrator may use this to generate host keys, | |
102 | as seen in | |
103 | .Pa /etc/rc . | |
104 | .Pp | |
105 | Normally this program generates the key and asks for a file in which | |
106 | to store the private key. | |
107 | The public key is stored in a file with the same name but | |
108 | .Dq .pub | |
109 | appended. | |
110 | The program also asks for a passphrase. | |
111 | The passphrase may be empty to indicate no passphrase | |
112 | (host keys must have an empty passphrase), or it may be a string of | |
113 | arbitrary length. | |
114 | Good passphrases are 10-30 characters long and are | |
115 | not simple sentences or otherwise easily guessable (English | |
116 | prose has only 1-2 bits of entropy per character, and provides very bad | |
117 | passphrases). | |
118 | The passphrase can be changed later by using the | |
119 | .Fl p | |
120 | option. | |
121 | .Pp | |
122 | There is no way to recover a lost passphrase. | |
123 | If the passphrase is | |
124 | lost or forgotten, a new key must be generated and copied to the | |
125 | corresponding public key to other machines. | |
126 | .Pp | |
127 | For RSA1 keys, | |
128 | there is also a comment field in the key file that is only for | |
129 | convenience to the user to help identify the key. | |
130 | The comment can tell what the key is for, or whatever is useful. | |
131 | The comment is initialized to | |
132 | .Dq user@host | |
133 | when the key is created, but can be changed using the | |
134 | .Fl c | |
135 | option. | |
136 | .Pp | |
137 | After a key is generated, instructions below detail where the keys | |
138 | should be placed to be activated. | |
139 | .Pp | |
140 | The options are as follows: | |
141 | .Bl -tag -width Ds | |
142 | .It Fl b Ar bits | |
143 | Specifies the number of bits in the key to create. | |
144 | Minimum is 512 bits. | |
145 | Generally 1024 bits is considered sufficient, and key sizes | |
146 | above that no longer improve security but make things slower. | |
147 | The default is 1024 bits. | |
148 | .It Fl c | |
149 | Requests changing the comment in the private and public key files. | |
150 | This operation is only supported for RSA1 keys. | |
151 | The program will prompt for the file containing the private keys, for | |
152 | the passphrase if the key has one, and for the new comment. | |
153 | .It Fl e | |
154 | This option will read a private or public OpenSSH key file and | |
155 | print the key in a | |
156 | .Sq SECSH Public Key File Format | |
157 | to stdout. | |
158 | This option allows exporting keys for use by several commercial | |
159 | SSH implementations. | |
160 | .It Fl f Ar filename | |
161 | Specifies the filename of the key file. | |
162 | .It Fl i | |
163 | This option will read an unencrypted private (or public) key file | |
164 | in SSH2-compatible format and print an OpenSSH compatible private | |
165 | (or public) key to stdout. | |
166 | .Nm | |
167 | also reads the | |
168 | .Sq SECSH Public Key File Format . | |
169 | This option allows importing keys from several commercial | |
170 | SSH implementations. | |
171 | .It Fl l | |
172 | Show fingerprint of specified public key file. | |
173 | Private RSA1 keys are also supported. | |
174 | For RSA and DSA keys | |
175 | .Nm | |
176 | tries to find the matching public key file and prints its fingerprint. | |
177 | .It Fl p | |
178 | Requests changing the passphrase of a private key file instead of | |
179 | creating a new private key. | |
180 | The program will prompt for the file | |
181 | containing the private key, for the old passphrase, and twice for the | |
182 | new passphrase. | |
183 | .It Fl q | |
184 | Silence | |
185 | .Nm ssh-keygen . | |
186 | Used by | |
187 | .Pa /etc/rc | |
188 | when creating a new key. | |
189 | .It Fl y | |
190 | This option will read a private | |
191 | OpenSSH format file and print an OpenSSH public key to stdout. | |
192 | .It Fl t Ar type | |
193 | Specifies the type of the key to create. | |
194 | The possible values are | |
195 | .Dq rsa1 | |
196 | for protocol version 1 and | |
197 | .Dq rsa | |
198 | or | |
199 | .Dq dsa | |
200 | for protocol version 2. | |
201 | The default is | |
202 | .Dq rsa1 . | |
203 | .It Fl B | |
204 | Show the bubblebabble digest of specified private or public key file. | |
205 | .It Fl C Ar comment | |
206 | Provides the new comment. | |
207 | .It Fl D Ar reader | |
208 | Download the RSA public key stored in the smartcard in | |
209 | .Ar reader . | |
210 | .It Fl N Ar new_passphrase | |
211 | Provides the new passphrase. | |
212 | .It Fl P Ar passphrase | |
213 | Provides the (old) passphrase. | |
214 | .It Fl U Ar reader | |
215 | Upload an existing RSA private key into the smartcard in | |
216 | .Ar reader . | |
217 | .El | |
218 | .Sh FILES | |
219 | .Bl -tag -width Ds | |
220 | .It Pa $HOME/.ssh/identity | |
221 | Contains the protocol version 1 RSA authentication identity of the user. | |
222 | This file should not be readable by anyone but the user. | |
223 | It is possible to | |
224 | specify a passphrase when generating the key; that passphrase will be | |
225 | used to encrypt the private part of this file using 3DES. | |
226 | This file is not automatically accessed by | |
227 | .Nm | |
228 | but it is offered as the default file for the private key. | |
229 | .Xr ssh 1 | |
230 | will read this file when a login attempt is made. | |
231 | .It Pa $HOME/.ssh/identity.pub | |
232 | Contains the protocol version 1 RSA public key for authentication. | |
233 | The contents of this file should be added to | |
234 | .Pa $HOME/.ssh/authorized_keys | |
235 | on all machines | |
236 | where the user wishes to log in using RSA authentication. | |
237 | There is no need to keep the contents of this file secret. | |
238 | .It Pa $HOME/.ssh/id_dsa | |
239 | Contains the protocol version 2 DSA authentication identity of the user. | |
240 | This file should not be readable by anyone but the user. | |
241 | It is possible to | |
242 | specify a passphrase when generating the key; that passphrase will be | |
243 | used to encrypt the private part of this file using 3DES. | |
244 | This file is not automatically accessed by | |
245 | .Nm | |
246 | but it is offered as the default file for the private key. | |
247 | .Xr ssh 1 | |
248 | will read this file when a login attempt is made. | |
249 | .It Pa $HOME/.ssh/id_dsa.pub | |
250 | Contains the protocol version 2 DSA public key for authentication. | |
251 | The contents of this file should be added to | |
252 | .Pa $HOME/.ssh/authorized_keys | |
253 | on all machines | |
254 | where the user wishes to log in using public key authentication. | |
255 | There is no need to keep the contents of this file secret. | |
256 | .It Pa $HOME/.ssh/id_rsa | |
257 | Contains the protocol version 2 RSA authentication identity of the user. | |
258 | This file should not be readable by anyone but the user. | |
259 | It is possible to | |
260 | specify a passphrase when generating the key; that passphrase will be | |
261 | used to encrypt the private part of this file using 3DES. | |
262 | This file is not automatically accessed by | |
263 | .Nm | |
264 | but it is offered as the default file for the private key. | |
265 | .Xr ssh 1 | |
266 | will read this file when a login attempt is made. | |
267 | .It Pa $HOME/.ssh/id_rsa.pub | |
268 | Contains the protocol version 2 RSA public key for authentication. | |
269 | The contents of this file should be added to | |
270 | .Pa $HOME/.ssh/authorized_keys | |
271 | on all machines | |
272 | where the user wishes to log in using public key authentication. | |
273 | There is no need to keep the contents of this file secret. | |
274 | .El | |
275 | .Sh AUTHORS | |
276 | OpenSSH is a derivative of the original and free | |
277 | ssh 1.2.12 release by Tatu Ylonen. | |
278 | Aaron Campbell, Bob Beck, Markus Friedl, Niels Provos, | |
279 | Theo de Raadt and Dug Song | |
280 | removed many bugs, re-added newer features and | |
281 | created OpenSSH. | |
282 | Markus Friedl contributed the support for SSH | |
283 | protocol versions 1.5 and 2.0. | |
284 | .Sh SEE ALSO | |
285 | .Xr ssh 1 , | |
286 | .Xr ssh-add 1 , | |
287 | .Xr ssh-agent 1 , | |
288 | .Xr sshd 8 | |
289 | .Rs | |
290 | .%A J. Galbraith | |
291 | .%A R. Thayer | |
292 | .%T "SECSH Public Key File Format" | |
293 | .%N draft-ietf-secsh-publickeyfile-01.txt | |
294 | .%D March 2001 | |
295 | .%O work in progress material | |
296 | .Re |