Annotation of src/usr.bin/ssh/ssh-keygen.1, Revision 1.33
1.33 ! deraadt 1: .\" $OpenBSD: ssh-keygen.1,v 1.32 2001/02/22 08:03:51 deraadt Exp $
1.29 niklas 2: .\"
1.1 deraadt 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: .\"
1.22 deraadt 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: .\"
1.33 ! deraadt 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.
1.22 deraadt 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.
1.1 deraadt 28: .\"
1.22 deraadt 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.
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1.1 deraadt 39: .\"
1.2 deraadt 40: .Dd September 25, 1999
41: .Dt SSH-KEYGEN 1
42: .Os
43: .Sh NAME
44: .Nm ssh-keygen
45: .Nd authentication key generation
46: .Sh SYNOPSIS
47: .Nm ssh-keygen
1.25 markus 48: .Op Fl q
1.2 deraadt 49: .Op Fl b Ar bits
1.25 markus 50: .Op Fl t Ar type
1.2 deraadt 51: .Op Fl N Ar new_passphrase
52: .Op Fl C Ar comment
1.20 markus 53: .Op Fl f Ar output_keyfile
1.2 deraadt 54: .Nm ssh-keygen
55: .Fl p
56: .Op Fl P Ar old_passphrase
57: .Op Fl N Ar new_passphrase
1.9 markus 58: .Op Fl f Ar keyfile
1.2 deraadt 59: .Nm ssh-keygen
1.16 deraadt 60: .Fl x
1.20 markus 61: .Op Fl f Ar input_keyfile
1.16 deraadt 62: .Nm ssh-keygen
63: .Fl X
1.20 markus 64: .Op Fl f Ar input_keyfile
1.16 deraadt 65: .Nm ssh-keygen
1.17 markus 66: .Fl y
1.20 markus 67: .Op Fl f Ar input_keyfile
1.17 markus 68: .Nm ssh-keygen
1.2 deraadt 69: .Fl c
70: .Op Fl P Ar passphrase
71: .Op Fl C Ar comment
1.9 markus 72: .Op Fl f Ar keyfile
73: .Nm ssh-keygen
74: .Fl l
1.20 markus 75: .Op Fl f Ar input_keyfile
1.13 aaron 76: .Sh DESCRIPTION
1.2 deraadt 77: .Nm
1.13 aaron 78: generates and manages authentication keys for
1.2 deraadt 79: .Xr ssh 1 .
1.15 deraadt 80: .Nm
81: defaults to generating an RSA key for use by protocols 1.3 and 1.5;
82: specifying the
1.25 markus 83: .Fl t
1.26 markus 84: option allows you to create a key for use by protocol 2.0.
1.15 deraadt 85: .Pp
1.2 deraadt 86: Normally each user wishing to use SSH
1.15 deraadt 87: with RSA or DSA authentication runs this once to create the authentication
1.1 deraadt 88: key in
1.15 deraadt 89: .Pa $HOME/.ssh/identity
90: or
91: .Pa $HOME/.ssh/id_dsa .
92: Additionally, the system administrator may use this to generate host keys,
93: as seen in
94: .Pa /etc/rc .
1.2 deraadt 95: .Pp
1.1 deraadt 96: Normally this program generates the key and asks for a file in which
1.12 aaron 97: to store the private key.
98: The public key is stored in a file with the same name but
1.2 deraadt 99: .Dq .pub
1.12 aaron 100: appended.
101: The program also asks for a passphrase.
102: The passphrase may be empty to indicate no passphrase
1.26 markus 103: (host keys must have an empty passphrase), or it may be a string of
1.12 aaron 104: arbitrary length.
105: Good passphrases are 10-30 characters long and are
1.1 deraadt 106: not simple sentences or otherwise easily guessable (English
107: prose has only 1-2 bits of entropy per word, and provides very bad
1.12 aaron 108: passphrases).
109: The passphrase can be changed later by using the
1.2 deraadt 110: .Fl p
1.1 deraadt 111: option.
1.2 deraadt 112: .Pp
1.12 aaron 113: There is no way to recover a lost passphrase.
114: If the passphrase is
1.1 deraadt 115: lost or forgotten, you will have to generate a new key and copy the
116: corresponding public key to other machines.
1.2 deraadt 117: .Pp
1.15 deraadt 118: For RSA, there is also a comment field in the key file that is only for
1.12 aaron 119: convenience to the user to help identify the key.
120: The comment can tell what the key is for, or whatever is useful.
121: The comment is initialized to
1.2 deraadt 122: .Dq user@host
123: when the key is created, but can be changed using the
124: .Fl c
1.1 deraadt 125: option.
1.2 deraadt 126: .Pp
1.15 deraadt 127: After a key is generated, instructions below detail where the keys
128: should be placed to be activated.
129: .Pp
1.2 deraadt 130: The options are as follows:
131: .Bl -tag -width Ds
132: .It Fl b Ar bits
1.12 aaron 133: Specifies the number of bits in the key to create.
134: Minimum is 512 bits.
135: Generally 1024 bits is considered sufficient, and key sizes
136: above that no longer improve security but make things slower.
137: The default is 1024 bits.
1.2 deraadt 138: .It Fl c
1.1 deraadt 139: Requests changing the comment in the private and public key files.
140: The program will prompt for the file containing the private keys, for
141: passphrase if the key has one, and for the new comment.
1.9 markus 142: .It Fl f
143: Specifies the filename of the key file.
144: .It Fl l
145: Show fingerprint of specified private or public key file.
1.2 deraadt 146: .It Fl p
1.1 deraadt 147: Requests changing the passphrase of a private key file instead of
1.12 aaron 148: creating a new private key.
149: The program will prompt for the file
1.1 deraadt 150: containing the private key, for the old passphrase, and twice for the
151: new passphrase.
1.5 aaron 152: .It Fl q
153: Silence
154: .Nm ssh-keygen .
155: Used by
156: .Pa /etc/rc
157: when creating a new key.
1.25 markus 158: .It Fl t Ar type
159: Specifies the type of the key to create.
160: The possible values are
161: .Dq rsa1
162: for protocol version 1 and
163: .Dq rsa
164: or
165: .Dq dsa
166: for protocol version 2.
167: The default is
1.31 deraadt 168: .Dq rsa1 .
1.2 deraadt 169: .It Fl C Ar comment
1.1 deraadt 170: Provides the new comment.
1.2 deraadt 171: .It Fl N Ar new_passphrase
1.1 deraadt 172: Provides the new passphrase.
1.2 deraadt 173: .It Fl P Ar passphrase
1.1 deraadt 174: Provides the (old) passphrase.
1.16 deraadt 175: .It Fl x
1.17 markus 176: This option will read a private
1.18 hugh 177: OpenSSH DSA format file and print a SSH2-compatible public key to stdout.
1.16 deraadt 178: .It Fl X
1.23 markus 179: This option will read a unencrypted
180: SSH2-compatible private (or public) key file and
181: print an OpenSSH compatible private (or public) key to stdout.
1.17 markus 182: .It Fl y
183: This option will read a private
1.25 markus 184: OpenSSH format file and print an OpenSSH public key to stdout.
1.2 deraadt 185: .El
186: .Sh FILES
187: .Bl -tag -width Ds
188: .It Pa $HOME/.ssh/identity
1.12 aaron 189: Contains the RSA authentication identity of the user.
190: This file should not be readable by anyone but the user.
191: It is possible to
1.1 deraadt 192: specify a passphrase when generating the key; that passphrase will be
1.12 aaron 193: used to encrypt the private part of this file using 3DES.
194: This file is not automatically accessed by
1.2 deraadt 195: .Nm
1.1 deraadt 196: but it is offered as the default file for the private key.
1.15 deraadt 197: .Xr sshd 8
198: will read this file when a login attempt is made.
1.2 deraadt 199: .It Pa $HOME/.ssh/identity.pub
1.12 aaron 200: Contains the public key for authentication.
201: The contents of this file should be added to
1.2 deraadt 202: .Pa $HOME/.ssh/authorized_keys
203: on all machines
1.12 aaron 204: where you wish to log in using RSA authentication.
1.15 deraadt 205: There is no need to keep the contents of this file secret.
206: .It Pa $HOME/.ssh/id_dsa
207: Contains the DSA authentication identity of the user.
208: This file should not be readable by anyone but the user.
209: It is possible to
210: specify a passphrase when generating the key; that passphrase will be
211: used to encrypt the private part of this file using 3DES.
212: This file is not automatically accessed by
213: .Nm
214: but it is offered as the default file for the private key.
215: .Xr sshd 8
216: will read this file when a login attempt is made.
217: .It Pa $HOME/.ssh/id_dsa.pub
218: Contains the public key for authentication.
219: The contents of this file should be added to
220: .Pa $HOME/.ssh/authorized_keys2
221: on all machines
1.25 markus 222: where you wish to log in using public key authentication.
1.12 aaron 223: There is no need to keep the contents of this file secret.
1.19 aaron 224: .El
1.24 aaron 225: .Sh AUTHORS
1.28 markus 226: OpenSSH is a derivative of the original and free
227: ssh 1.2.12 release by Tatu Ylonen.
228: Aaron Campbell, Bob Beck, Markus Friedl, Niels Provos,
229: Theo de Raadt and Dug Song
230: removed many bugs, re-added newer features and
231: created OpenSSH.
232: Markus Friedl contributed the support for SSH
233: protocol versions 1.5 and 2.0.
1.2 deraadt 234: .Sh SEE ALSO
235: .Xr ssh 1 ,
236: .Xr ssh-add 1 ,
1.8 ericj 237: .Xr ssh-agent 1 ,
1.30 itojun 238: .Xr sshd 8