3 .\" Author: Tatu Ylonen <ylo@cs.hut.fi>
4 .\" Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
5 .\" All rights reserved
7 .\" As far as I am concerned, the code I have written for this software
8 .\" can be used freely for any purpose. Any derived versions of this
9 .\" software must be clearly marked as such, and if the derived work is
10 .\" incompatible with the protocol description in the RFC file, it must be
11 .\" called by a name other than "ssh" or "Secure Shell".
14 .\" Copyright (c) 1999,2000 Markus Friedl. All rights reserved.
15 .\" Copyright (c) 1999 Aaron Campbell. All rights reserved.
16 .\" Copyright (c) 1999 Theo de Raadt. All rights reserved.
18 .\" Redistribution and use in source and binary forms, with or without
19 .\" modification, are permitted provided that the following conditions
21 .\" 1. Redistributions of source code must retain the above copyright
22 .\" notice, this list of conditions and the following disclaimer.
23 .\" 2. Redistributions in binary form must reproduce the above copyright
24 .\" notice, this list of conditions and the following disclaimer in the
25 .\" documentation and/or other materials provided with the distribution.
27 .\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
28 .\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
29 .\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
30 .\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
31 .\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
32 .\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
33 .\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
34 .\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
35 .\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
36 .\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
38 .Dd September 25, 1999
43 .Nd authentication key generation
49 .Op Fl N Ar new_passphrase
51 .Op Fl f Ar output_keyfile
54 .Op Fl P Ar old_passphrase
55 .Op Fl N Ar new_passphrase
59 .Op Fl f Ar input_keyfile
62 .Op Fl f Ar input_keyfile
65 .Op Fl f Ar input_keyfile
68 .Op Fl P Ar passphrase
73 .Op Fl f Ar input_keyfile
76 generates and manages authentication keys for
79 defaults to generating an RSA key for use by protocols 1.3 and 1.5;
82 option allows you to create a key for use by protocol 2.0.
84 Normally each user wishing to use SSH
85 with RSA or DSA authentication runs this once to create the authentication
87 .Pa $HOME/.ssh/identity
89 .Pa $HOME/.ssh/id_dsa .
90 Additionally, the system administrator may use this to generate host keys,
94 Normally this program generates the key and asks for a file in which
95 to store the private key.
96 The public key is stored in a file with the same name but
99 The program also asks for a passphrase.
100 The passphrase may be empty to indicate no passphrase
101 (host keys must have an empty passphrase), or it may be a string of
103 Good passphrases are 10-30 characters long and are
104 not simple sentences or otherwise easily guessable (English
105 prose has only 1-2 bits of entropy per word, and provides very bad
107 The passphrase can be changed later by using the
111 There is no way to recover a lost passphrase.
113 lost or forgotten, you will have to generate a new key and copy the
114 corresponding public key to other machines.
116 For RSA, there is also a comment field in the key file that is only for
117 convenience to the user to help identify the key.
118 The comment can tell what the key is for, or whatever is useful.
119 The comment is initialized to
121 when the key is created, but can be changed using the
125 After a key is generated, instructions below detail where the keys
126 should be placed to be activated.
128 The options are as follows:
131 Specifies the number of bits in the key to create.
133 Generally 1024 bits is considered sufficient, and key sizes
134 above that no longer improve security but make things slower.
135 The default is 1024 bits.
137 Requests changing the comment in the private and public key files.
138 The program will prompt for the file containing the private keys, for
139 passphrase if the key has one, and for the new comment.
141 Specifies the filename of the key file.
143 Show fingerprint of specified private or public key file.
145 Requests changing the passphrase of a private key file instead of
146 creating a new private key.
147 The program will prompt for the file
148 containing the private key, for the old passphrase, and twice for the
155 when creating a new key.
157 Specifies the type of the key to create.
158 The possible values are
160 for protocol version 1 and
164 for protocol version 2.
168 Provides the new comment.
169 .It Fl N Ar new_passphrase
170 Provides the new passphrase.
171 .It Fl P Ar passphrase
172 Provides the (old) passphrase.
174 This option will read a private
175 OpenSSH DSA format file and print a SSH2-compatible public key to stdout.
177 This option will read a unencrypted
178 SSH2-compatible private (or public) key file and
179 print an OpenSSH compatible private (or public) key to stdout.
181 This option will read a private
182 OpenSSH format file and print an OpenSSH public key to stdout.
186 .It Pa $HOME/.ssh/identity
187 Contains the RSA authentication identity of the user.
188 This file should not be readable by anyone but the user.
190 specify a passphrase when generating the key; that passphrase will be
191 used to encrypt the private part of this file using 3DES.
192 This file is not automatically accessed by
194 but it is offered as the default file for the private key.
196 will read this file when a login attempt is made.
197 .It Pa $HOME/.ssh/identity.pub
198 Contains the public key for authentication.
199 The contents of this file should be added to
200 .Pa $HOME/.ssh/authorized_keys
202 where you wish to log in using RSA authentication.
203 There is no need to keep the contents of this file secret.
204 .It Pa $HOME/.ssh/id_dsa
205 Contains the DSA authentication identity of the user.
206 This file should not be readable by anyone but the user.
208 specify a passphrase when generating the key; that passphrase will be
209 used to encrypt the private part of this file using 3DES.
210 This file is not automatically accessed by
212 but it is offered as the default file for the private key.
214 will read this file when a login attempt is made.
215 .It Pa $HOME/.ssh/id_dsa.pub
216 Contains the public key for authentication.
217 The contents of this file should be added to
218 .Pa $HOME/.ssh/authorized_keys2
220 where you wish to log in using public key authentication.
221 There is no need to keep the contents of this file secret.
224 Tatu Ylonen <ylo@cs.hut.fi>
227 is a derivative of the original (free) ssh 1.2.12 release, but with bugs
228 removed and newer features re-added.
229 Rapidly after the 1.2.12 release,
230 newer versions bore successively more restrictive licenses.
231 This version of OpenSSH
234 has all components of a restrictive nature (i.e., patents, see
236 directly removed from the source code; any licensed or patented components
240 has been updated to support ssh protocol 1.5.
242 contains added support for
244 authentication and ticket passing.
246 supports one-time password authentication with