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bf740959 | 1 | .\" -*- nroff -*- |
2 | .\" | |
3 | .\" ssh-keygen.1 | |
4 | .\" | |
5 | .\" Author: Tatu Ylonen <ylo@cs.hut.fi> | |
6 | .\" | |
7 | .\" Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland | |
8 | .\" All rights reserved | |
9 | .\" | |
10 | .\" Created: Sat Apr 22 23:55:14 1995 ylo | |
11 | .\" | |
12 | .\" $Id$ | |
13 | .\" | |
14 | .Dd September 25, 1999 | |
15 | .Dt SSH-KEYGEN 1 | |
16 | .Os | |
17 | .Sh NAME | |
18 | .Nm ssh-keygen | |
19 | .Nd authentication key generation | |
20 | .Sh SYNOPSIS | |
21 | .Nm ssh-keygen | |
22 | .Op Fl q | |
23 | .Op Fl b Ar bits | |
24 | .Op Fl N Ar new_passphrase | |
25 | .Op Fl C Ar comment | |
f095fcc7 | 26 | .Op Fl f Ar keyfile |
bf740959 | 27 | .Nm ssh-keygen |
28 | .Fl p | |
29 | .Op Fl P Ar old_passphrase | |
30 | .Op Fl N Ar new_passphrase | |
f095fcc7 | 31 | .Op Fl f Ar keyfile |
bf740959 | 32 | .Nm ssh-keygen |
33 | .Fl c | |
34 | .Op Fl P Ar passphrase | |
35 | .Op Fl C Ar comment | |
f095fcc7 | 36 | .Op Fl f Ar keyfile |
37 | .Nm ssh-keygen | |
38 | .Fl l | |
39 | .Op Fl f Ar keyfile | |
bf740959 | 40 | .Sh DESCRIPTION |
41 | .Nm | |
42 | generates and manages authentication keys for | |
43 | .Xr ssh 1 . | |
44 | Normally each user wishing to use SSH | |
45 | with RSA authentication runs this once to create the authentication | |
46 | key in | |
47 | .Pa $HOME/.ssh/identity . | |
48 | Additionally, the system administrator may use this to generate host keys. | |
49 | .Pp | |
50 | Normally this program generates the key and asks for a file in which | |
4fe2af09 | 51 | to store the private key. |
52 | The public key is stored in a file with the same name but | |
bf740959 | 53 | .Dq .pub |
4fe2af09 | 54 | appended. |
55 | The program also asks for a passphrase. | |
56 | The passphrase may be empty to indicate no passphrase | |
bf740959 | 57 | (host keys must have empty passphrase), or it may be a string of |
4fe2af09 | 58 | arbitrary length. |
59 | Good passphrases are 10-30 characters long and are | |
bf740959 | 60 | not simple sentences or otherwise easily guessable (English |
61 | prose has only 1-2 bits of entropy per word, and provides very bad | |
4fe2af09 | 62 | passphrases). |
63 | The passphrase can be changed later by using the | |
bf740959 | 64 | .Fl p |
65 | option. | |
66 | .Pp | |
4fe2af09 | 67 | There is no way to recover a lost passphrase. |
68 | If the passphrase is | |
bf740959 | 69 | lost or forgotten, you will have to generate a new key and copy the |
70 | corresponding public key to other machines. | |
71 | .Pp | |
72 | There is also a comment field in the key file that is only for | |
4fe2af09 | 73 | convenience to the user to help identify the key. |
74 | The comment can tell what the key is for, or whatever is useful. | |
75 | The comment is initialized to | |
bf740959 | 76 | .Dq user@host |
77 | when the key is created, but can be changed using the | |
78 | .Fl c | |
79 | option. | |
80 | .Pp | |
81 | The options are as follows: | |
82 | .Bl -tag -width Ds | |
83 | .It Fl b Ar bits | |
4fe2af09 | 84 | Specifies the number of bits in the key to create. |
85 | Minimum is 512 bits. | |
86 | Generally 1024 bits is considered sufficient, and key sizes | |
87 | above that no longer improve security but make things slower. | |
88 | The default is 1024 bits. | |
bf740959 | 89 | .It Fl c |
90 | Requests changing the comment in the private and public key files. | |
91 | The program will prompt for the file containing the private keys, for | |
92 | passphrase if the key has one, and for the new comment. | |
f095fcc7 | 93 | .It Fl f |
94 | Specifies the filename of the key file. | |
95 | .It Fl l | |
96 | Show fingerprint of specified private or public key file. | |
bf740959 | 97 | .It Fl p |
98 | Requests changing the passphrase of a private key file instead of | |
4fe2af09 | 99 | creating a new private key. |
100 | The program will prompt for the file | |
bf740959 | 101 | containing the private key, for the old passphrase, and twice for the |
102 | new passphrase. | |
103 | .It Fl q | |
104 | Silence | |
105 | .Nm ssh-keygen . | |
106 | Used by | |
107 | .Pa /etc/rc | |
108 | when creating a new key. | |
109 | .It Fl C Ar comment | |
110 | Provides the new comment. | |
111 | .It Fl N Ar new_passphrase | |
112 | Provides the new passphrase. | |
113 | .It Fl P Ar passphrase | |
114 | Provides the (old) passphrase. | |
115 | .El | |
116 | .Sh FILES | |
117 | .Bl -tag -width Ds | |
bf740959 | 118 | .It Pa $HOME/.ssh/identity |
4fe2af09 | 119 | Contains the RSA authentication identity of the user. |
120 | This file should not be readable by anyone but the user. | |
121 | It is possible to | |
bf740959 | 122 | specify a passphrase when generating the key; that passphrase will be |
4fe2af09 | 123 | used to encrypt the private part of this file using 3DES. |
124 | This file is not automatically accessed by | |
bf740959 | 125 | .Nm |
126 | but it is offered as the default file for the private key. | |
127 | .It Pa $HOME/.ssh/identity.pub | |
4fe2af09 | 128 | Contains the public key for authentication. |
129 | The contents of this file should be added to | |
bf740959 | 130 | .Pa $HOME/.ssh/authorized_keys |
131 | on all machines | |
4fe2af09 | 132 | where you wish to log in using RSA authentication. |
133 | There is no need to keep the contents of this file secret. | |
bf740959 | 134 | .Sh AUTHOR |
135 | Tatu Ylonen <ylo@cs.hut.fi> | |
136 | .Pp | |
137 | OpenSSH | |
138 | is a derivative of the original (free) ssh 1.2.12 release, but with bugs | |
4fe2af09 | 139 | removed and newer features re-added. |
140 | Rapidly after the 1.2.12 release, | |
141 | newer versions bore successively more restrictive licenses. | |
142 | This version of OpenSSH | |
bf740959 | 143 | .Bl -bullet |
144 | .It | |
399d9d44 | 145 | has all components of a restrictive nature (i.e., patents, see |
bf740959 | 146 | .Xr ssl 8 ) |
147 | directly removed from the source code; any licensed or patented components | |
148 | are chosen from | |
149 | external libraries. | |
150 | .It | |
151 | has been updated to support ssh protocol 1.5. | |
152 | .It | |
153 | contains added support for | |
154 | .Xr kerberos 8 | |
155 | authentication and ticket passing. | |
156 | .It | |
157 | supports one-time password authentication with | |
158 | .Xr skey 1 . | |
159 | .El | |
160 | .Pp | |
161 | The libraries described in | |
162 | .Xr ssl 8 | |
163 | are required for proper operation. | |
164 | .Sh SEE ALSO | |
165 | .Xr ssh 1 , | |
166 | .Xr ssh-add 1 , | |
0c372277 | 167 | .Xr ssh-agent 1 , |
bf740959 | 168 | .Xr sshd 8 , |
169 | .Xr ssl 8 |