diff options
author | Colin Watson <cjwatson@debian.org> | 2010-08-23 22:50:14 +0100 |
---|---|---|
committer | Colin Watson <cjwatson@debian.org> | 2010-08-23 22:50:14 +0100 |
commit | 43094ebf14c9b16f1ea398bc5b65a7335e947288 (patch) | |
tree | 10f5da5fe4f61992d238da7a71692157a609c819 /ssh-keygen.0 | |
parent | 4b8ebe7e3647d3078fd4d025f4325b8cc1ac20d6 (diff) | |
parent | ff0095389ba9a9e4599e6051c8d5bae6777c4d64 (diff) |
Import 5.6p1 tarball
Diffstat (limited to 'ssh-keygen.0')
-rw-r--r-- | ssh-keygen.0 | 456 |
1 files changed, 456 insertions, 0 deletions
diff --git a/ssh-keygen.0 b/ssh-keygen.0 new file mode 100644 index 000000000..fb7838724 --- /dev/null +++ b/ssh-keygen.0 | |||
@@ -0,0 +1,456 @@ | |||
1 | SSH-KEYGEN(1) OpenBSD Reference Manual SSH-KEYGEN(1) | ||
2 | |||
3 | NAME | ||
4 | ssh-keygen - authentication key generation, management and conversion | ||
5 | |||
6 | SYNOPSIS | ||
7 | ssh-keygen [-q] [-b bits] -t type [-N new_passphrase] [-C comment] | ||
8 | [-f output_keyfile] | ||
9 | ssh-keygen -p [-P old_passphrase] [-N new_passphrase] [-f keyfile] | ||
10 | ssh-keygen -i [-m key_format] [-f input_keyfile] | ||
11 | ssh-keygen -e [-m key_format] [-f input_keyfile] | ||
12 | ssh-keygen -y [-f input_keyfile] | ||
13 | ssh-keygen -c [-P passphrase] [-C comment] [-f keyfile] | ||
14 | ssh-keygen -l [-f input_keyfile] | ||
15 | ssh-keygen -B [-f input_keyfile] | ||
16 | ssh-keygen -D pkcs11 | ||
17 | ssh-keygen -F hostname [-f known_hosts_file] [-l] | ||
18 | ssh-keygen -H [-f known_hosts_file] | ||
19 | ssh-keygen -R hostname [-f known_hosts_file] | ||
20 | ssh-keygen -r hostname [-f input_keyfile] [-g] | ||
21 | ssh-keygen -G output_file [-v] [-b bits] [-M memory] [-S start_point] | ||
22 | ssh-keygen -T output_file -f input_file [-v] [-a num_trials] | ||
23 | [-W generator] | ||
24 | ssh-keygen -s ca_key -I certificate_identity [-h] [-n principals] | ||
25 | [-O option] [-V validity_interval] [-z serial_number] file ... | ||
26 | ssh-keygen -L [-f input_keyfile] | ||
27 | |||
28 | DESCRIPTION | ||
29 | ssh-keygen generates, manages and converts authentication keys for | ||
30 | ssh(1). ssh-keygen can create RSA keys for use by SSH protocol version 1 | ||
31 | and RSA or DSA keys for use by SSH protocol version 2. The type of key | ||
32 | to be generated is specified with the -t option. If invoked without any | ||
33 | arguments, ssh-keygen will generate an RSA key for use in SSH protocol 2 | ||
34 | connections. | ||
35 | |||
36 | ssh-keygen is also used to generate groups for use in Diffie-Hellman | ||
37 | group exchange (DH-GEX). See the MODULI GENERATION section for details. | ||
38 | |||
39 | Normally each user wishing to use SSH with RSA or DSA authentication runs | ||
40 | this once to create the authentication key in ~/.ssh/identity, | ||
41 | ~/.ssh/id_dsa or ~/.ssh/id_rsa. Additionally, the system administrator | ||
42 | may use this to generate host keys, as seen in /etc/rc. | ||
43 | |||
44 | Normally this program generates the key and asks for a file in which to | ||
45 | store the private key. The public key is stored in a file with the same | ||
46 | name but ``.pub'' appended. The program also asks for a passphrase. The | ||
47 | passphrase may be empty to indicate no passphrase (host keys must have an | ||
48 | empty passphrase), or it may be a string of arbitrary length. A | ||
49 | passphrase is similar to a password, except it can be a phrase with a | ||
50 | series of words, punctuation, numbers, whitespace, or any string of | ||
51 | characters you want. Good passphrases are 10-30 characters long, are not | ||
52 | simple sentences or otherwise easily guessable (English prose has only 1- | ||
53 | 2 bits of entropy per character, and provides very bad passphrases), and | ||
54 | contain a mix of upper and lowercase letters, numbers, and non- | ||
55 | alphanumeric characters. The passphrase can be changed later by using | ||
56 | the -p option. | ||
57 | |||
58 | There is no way to recover a lost passphrase. If the passphrase is lost | ||
59 | or forgotten, a new key must be generated and copied to the corresponding | ||
60 | public key to other machines. | ||
61 | |||
62 | For RSA1 keys, there is also a comment field in the key file that is only | ||
63 | for convenience to the user to help identify the key. The comment can | ||
64 | tell what the key is for, or whatever is useful. The comment is | ||
65 | initialized to ``user@host'' when the key is created, but can be changed | ||
66 | using the -c option. | ||
67 | |||
68 | After a key is generated, instructions below detail where the keys should | ||
69 | be placed to be activated. | ||
70 | |||
71 | The options are as follows: | ||
72 | |||
73 | -a trials | ||
74 | Specifies the number of primality tests to perform when screening | ||
75 | DH-GEX candidates using the -T command. | ||
76 | |||
77 | -B Show the bubblebabble digest of specified private or public key | ||
78 | file. | ||
79 | |||
80 | -b bits | ||
81 | Specifies the number of bits in the key to create. For RSA keys, | ||
82 | the minimum size is 768 bits and the default is 2048 bits. | ||
83 | Generally, 2048 bits is considered sufficient. DSA keys must be | ||
84 | exactly 1024 bits as specified by FIPS 186-2. | ||
85 | |||
86 | -C comment | ||
87 | Provides a new comment. | ||
88 | |||
89 | -c Requests changing the comment in the private and public key | ||
90 | files. This operation is only supported for RSA1 keys. The | ||
91 | program will prompt for the file containing the private keys, for | ||
92 | the passphrase if the key has one, and for the new comment. | ||
93 | |||
94 | -D pkcs11 | ||
95 | Download the RSA public keys provided by the PKCS#11 shared | ||
96 | library pkcs11. When used in combination with -s, this option | ||
97 | indicates that a CA key resides in a PKCS#11 token (see the | ||
98 | CERTIFICATES section for details). | ||
99 | |||
100 | -e This option will read a private or public OpenSSH key file and | ||
101 | print to stdout the key in one of the formats specified by the -m | ||
102 | option. The default export format is ``RFC4716''. This option | ||
103 | allows exporting OpenSSH keys for use by other programs, | ||
104 | including several commercial SSH implementations. | ||
105 | |||
106 | -F hostname | ||
107 | Search for the specified hostname in a known_hosts file, listing | ||
108 | any occurrences found. This option is useful to find hashed host | ||
109 | names or addresses and may also be used in conjunction with the | ||
110 | -H option to print found keys in a hashed format. | ||
111 | |||
112 | -f filename | ||
113 | Specifies the filename of the key file. | ||
114 | |||
115 | -G output_file | ||
116 | Generate candidate primes for DH-GEX. These primes must be | ||
117 | screened for safety (using the -T option) before use. | ||
118 | |||
119 | -g Use generic DNS format when printing fingerprint resource records | ||
120 | using the -r command. | ||
121 | |||
122 | -H Hash a known_hosts file. This replaces all hostnames and | ||
123 | addresses with hashed representations within the specified file; | ||
124 | the original content is moved to a file with a .old suffix. | ||
125 | These hashes may be used normally by ssh and sshd, but they do | ||
126 | not reveal identifying information should the file's contents be | ||
127 | disclosed. This option will not modify existing hashed hostnames | ||
128 | and is therefore safe to use on files that mix hashed and non- | ||
129 | hashed names. | ||
130 | |||
131 | -h When signing a key, create a host certificate instead of a user | ||
132 | certificate. Please see the CERTIFICATES section for details. | ||
133 | |||
134 | -I certificate_identity | ||
135 | Specify the key identity when signing a public key. Please see | ||
136 | the CERTIFICATES section for details. | ||
137 | |||
138 | -i This option will read an unencrypted private (or public) key file | ||
139 | in the format specified by the -m option and print an OpenSSH | ||
140 | compatible private (or public) key to stdout. This option allows | ||
141 | importing keys from other software, including several commercial | ||
142 | SSH implementations. The default import format is ``RFC4716''. | ||
143 | |||
144 | -L Prints the contents of a certificate. | ||
145 | |||
146 | -l Show fingerprint of specified public key file. Private RSA1 keys | ||
147 | are also supported. For RSA and DSA keys ssh-keygen tries to | ||
148 | find the matching public key file and prints its fingerprint. If | ||
149 | combined with -v, an ASCII art representation of the key is | ||
150 | supplied with the fingerprint. | ||
151 | |||
152 | -M memory | ||
153 | Specify the amount of memory to use (in megabytes) when | ||
154 | generating candidate moduli for DH-GEX. | ||
155 | |||
156 | -m key_format | ||
157 | Specify a key format for the -i (import) or -e (export) | ||
158 | conversion options. The supported key formats are: ``RFC4716'' | ||
159 | (RFC 4716/SSH2 public or private key), ``PKCS8'' (PEM PKCS8 | ||
160 | public key) or ``PEM'' (PEM public key). The default conversion | ||
161 | format is ``RFC4716''. | ||
162 | |||
163 | -N new_passphrase | ||
164 | Provides the new passphrase. | ||
165 | |||
166 | -n principals | ||
167 | Specify one or more principals (user or host names) to be | ||
168 | included in a certificate when signing a key. Multiple | ||
169 | principals may be specified, separated by commas. Please see the | ||
170 | CERTIFICATES section for details. | ||
171 | |||
172 | -O option | ||
173 | Specify a certificate option when signing a key. This option may | ||
174 | be specified multiple times. Please see the CERTIFICATES section | ||
175 | for details. The options that are valid for user certificates | ||
176 | are: | ||
177 | |||
178 | clear Clear all enabled permissions. This is useful for | ||
179 | clearing the default set of permissions so permissions | ||
180 | may be added individually. | ||
181 | |||
182 | force-command=command | ||
183 | Forces the execution of command instead of any shell or | ||
184 | command specified by the user when the certificate is | ||
185 | used for authentication. | ||
186 | |||
187 | no-agent-forwarding | ||
188 | Disable ssh-agent(1) forwarding (permitted by default). | ||
189 | |||
190 | no-port-forwarding | ||
191 | Disable port forwarding (permitted by default). | ||
192 | |||
193 | no-pty Disable PTY allocation (permitted by default). | ||
194 | |||
195 | no-user-rc | ||
196 | Disable execution of ~/.ssh/rc by sshd(8) (permitted by | ||
197 | default). | ||
198 | |||
199 | no-x11-forwarding | ||
200 | Disable X11 forwarding (permitted by default). | ||
201 | |||
202 | permit-agent-forwarding | ||
203 | Allows ssh-agent(1) forwarding. | ||
204 | |||
205 | permit-port-forwarding | ||
206 | Allows port forwarding. | ||
207 | |||
208 | permit-pty | ||
209 | Allows PTY allocation. | ||
210 | |||
211 | permit-user-rc | ||
212 | Allows execution of ~/.ssh/rc by sshd(8). | ||
213 | |||
214 | permit-x11-forwarding | ||
215 | Allows X11 forwarding. | ||
216 | |||
217 | source-address=address_list | ||
218 | Restrict the source addresses from which the certificate | ||
219 | is considered valid. The address_list is a comma- | ||
220 | separated list of one or more address/netmask pairs in | ||
221 | CIDR format. | ||
222 | |||
223 | At present, no options are valid for host keys. | ||
224 | |||
225 | -P passphrase | ||
226 | Provides the (old) passphrase. | ||
227 | |||
228 | -p Requests changing the passphrase of a private key file instead of | ||
229 | creating a new private key. The program will prompt for the file | ||
230 | containing the private key, for the old passphrase, and twice for | ||
231 | the new passphrase. | ||
232 | |||
233 | -q Silence ssh-keygen. Used by /etc/rc when creating a new key. | ||
234 | |||
235 | -R hostname | ||
236 | Removes all keys belonging to hostname from a known_hosts file. | ||
237 | This option is useful to delete hashed hosts (see the -H option | ||
238 | above). | ||
239 | |||
240 | -r hostname | ||
241 | Print the SSHFP fingerprint resource record named hostname for | ||
242 | the specified public key file. | ||
243 | |||
244 | -S start | ||
245 | Specify start point (in hex) when generating candidate moduli for | ||
246 | DH-GEX. | ||
247 | |||
248 | -s ca_key | ||
249 | Certify (sign) a public key using the specified CA key. Please | ||
250 | see the CERTIFICATES section for details. | ||
251 | |||
252 | -T output_file | ||
253 | Test DH group exchange candidate primes (generated using the -G | ||
254 | option) for safety. | ||
255 | |||
256 | -t type | ||
257 | Specifies the type of key to create. The possible values are | ||
258 | ``rsa1'' for protocol version 1 and ``rsa'' or ``dsa'' for | ||
259 | protocol version 2. | ||
260 | |||
261 | -V validity_interval | ||
262 | Specify a validity interval when signing a certificate. A | ||
263 | validity interval may consist of a single time, indicating that | ||
264 | the certificate is valid beginning now and expiring at that time, | ||
265 | or may consist of two times separated by a colon to indicate an | ||
266 | explicit time interval. The start time may be specified as a | ||
267 | date in YYYYMMDD format, a time in YYYYMMDDHHMMSS format or a | ||
268 | relative time (to the current time) consisting of a minus sign | ||
269 | followed by a relative time in the format described in the TIME | ||
270 | FORMATS section of sshd_config(5). The end time may be specified | ||
271 | as a YYYYMMDD date, a YYYYMMDDHHMMSS time or a relative time | ||
272 | starting with a plus character. | ||
273 | |||
274 | For example: ``+52w1d'' (valid from now to 52 weeks and one day | ||
275 | from now), ``-4w:+4w'' (valid from four weeks ago to four weeks | ||
276 | from now), ``20100101123000:20110101123000'' (valid from 12:30 | ||
277 | PM, January 1st, 2010 to 12:30 PM, January 1st, 2011), | ||
278 | ``-1d:20110101'' (valid from yesterday to midnight, January 1st, | ||
279 | 2011). | ||
280 | |||
281 | -v Verbose mode. Causes ssh-keygen to print debugging messages | ||
282 | about its progress. This is helpful for debugging moduli | ||
283 | generation. Multiple -v options increase the verbosity. The | ||
284 | maximum is 3. | ||
285 | |||
286 | -W generator | ||
287 | Specify desired generator when testing candidate moduli for DH- | ||
288 | GEX. | ||
289 | |||
290 | -y This option will read a private OpenSSH format file and print an | ||
291 | OpenSSH public key to stdout. | ||
292 | |||
293 | -z serial_number | ||
294 | Specifies a serial number to be embedded in the certificate to | ||
295 | distinguish this certificate from others from the same CA. The | ||
296 | default serial number is zero. | ||
297 | |||
298 | MODULI GENERATION | ||
299 | ssh-keygen may be used to generate groups for the Diffie-Hellman Group | ||
300 | Exchange (DH-GEX) protocol. Generating these groups is a two-step | ||
301 | process: first, candidate primes are generated using a fast, but memory | ||
302 | intensive process. These candidate primes are then tested for | ||
303 | suitability (a CPU-intensive process). | ||
304 | |||
305 | Generation of primes is performed using the -G option. The desired | ||
306 | length of the primes may be specified by the -b option. For example: | ||
307 | |||
308 | # ssh-keygen -G moduli-2048.candidates -b 2048 | ||
309 | |||
310 | By default, the search for primes begins at a random point in the desired | ||
311 | length range. This may be overridden using the -S option, which | ||
312 | specifies a different start point (in hex). | ||
313 | |||
314 | Once a set of candidates have been generated, they must be tested for | ||
315 | suitability. This may be performed using the -T option. In this mode | ||
316 | ssh-keygen will read candidates from standard input (or a file specified | ||
317 | using the -f option). For example: | ||
318 | |||
319 | # ssh-keygen -T moduli-2048 -f moduli-2048.candidates | ||
320 | |||
321 | By default, each candidate will be subjected to 100 primality tests. | ||
322 | This may be overridden using the -a option. The DH generator value will | ||
323 | be chosen automatically for the prime under consideration. If a specific | ||
324 | generator is desired, it may be requested using the -W option. Valid | ||
325 | generator values are 2, 3, and 5. | ||
326 | |||
327 | Screened DH groups may be installed in /etc/moduli. It is important that | ||
328 | this file contains moduli of a range of bit lengths and that both ends of | ||
329 | a connection share common moduli. | ||
330 | |||
331 | CERTIFICATES | ||
332 | ssh-keygen supports signing of keys to produce certificates that may be | ||
333 | used for user or host authentication. Certificates consist of a public | ||
334 | key, some identity information, zero or more principal (user or host) | ||
335 | names and a set of options that are signed by a Certification Authority | ||
336 | (CA) key. Clients or servers may then trust only the CA key and verify | ||
337 | its signature on a certificate rather than trusting many user/host keys. | ||
338 | Note that OpenSSH certificates are a different, and much simpler, format | ||
339 | to the X.509 certificates used in ssl(8). | ||
340 | |||
341 | ssh-keygen supports two types of certificates: user and host. User | ||
342 | certificates authenticate users to servers, whereas host certificates | ||
343 | authenticate server hosts to users. To generate a user certificate: | ||
344 | |||
345 | $ ssh-keygen -s /path/to/ca_key -I key_id /path/to/user_key.pub | ||
346 | |||
347 | The resultant certificate will be placed in /path/to/user_key-cert.pub. | ||
348 | A host certificate requires the -h option: | ||
349 | |||
350 | $ ssh-keygen -s /path/to/ca_key -I key_id -h /path/to/host_key.pub | ||
351 | |||
352 | The host certificate will be output to /path/to/host_key-cert.pub. | ||
353 | |||
354 | It is possible to sign using a CA key stored in a PKCS#11 token by | ||
355 | providing the token library using -D and identifying the CA key by | ||
356 | providing its public half as an argument to -s: | ||
357 | |||
358 | $ ssh-keygen -s ca_key.pub -D libpkcs11.so -I key_id host_key.pub | ||
359 | |||
360 | In all cases, key_id is a "key identifier" that is logged by the server | ||
361 | when the certificate is used for authentication. | ||
362 | |||
363 | Certificates may be limited to be valid for a set of principal | ||
364 | (user/host) names. By default, generated certificates are valid for all | ||
365 | users or hosts. To generate a certificate for a specified set of | ||
366 | principals: | ||
367 | |||
368 | $ ssh-keygen -s ca_key -I key_id -n user1,user2 user_key.pub | ||
369 | $ ssh-keygen -s ca_key -I key_id -h -n host.domain user_key.pub | ||
370 | |||
371 | Additional limitations on the validity and use of user certificates may | ||
372 | be specified through certificate options. A certificate option may | ||
373 | disable features of the SSH session, may be valid only when presented | ||
374 | from particular source addresses or may force the use of a specific | ||
375 | command. For a list of valid certificate options, see the documentation | ||
376 | for the -O option above. | ||
377 | |||
378 | Finally, certificates may be defined with a validity lifetime. The -V | ||
379 | option allows specification of certificate start and end times. A | ||
380 | certificate that is presented at a time outside this range will not be | ||
381 | considered valid. By default, certificates have a maximum validity | ||
382 | interval. | ||
383 | |||
384 | For certificates to be used for user or host authentication, the CA | ||
385 | public key must be trusted by sshd(8) or ssh(1). Please refer to those | ||
386 | manual pages for details. | ||
387 | |||
388 | FILES | ||
389 | ~/.ssh/identity | ||
390 | Contains the protocol version 1 RSA authentication identity of | ||
391 | the user. This file should not be readable by anyone but the | ||
392 | user. It is possible to specify a passphrase when generating the | ||
393 | key; that passphrase will be used to encrypt the private part of | ||
394 | this file using 128-bit AES. This file is not automatically | ||
395 | accessed by ssh-keygen but it is offered as the default file for | ||
396 | the private key. ssh(1) will read this file when a login attempt | ||
397 | is made. | ||
398 | |||
399 | ~/.ssh/identity.pub | ||
400 | Contains the protocol version 1 RSA public key for | ||
401 | authentication. The contents of this file should be added to | ||
402 | ~/.ssh/authorized_keys on all machines where the user wishes to | ||
403 | log in using RSA authentication. There is no need to keep the | ||
404 | contents of this file secret. | ||
405 | |||
406 | ~/.ssh/id_dsa | ||
407 | Contains the protocol version 2 DSA authentication identity of | ||
408 | the user. This file should not be readable by anyone but the | ||
409 | user. It is possible to specify a passphrase when generating the | ||
410 | key; that passphrase will be used to encrypt the private part of | ||
411 | this file using 128-bit AES. This file is not automatically | ||
412 | accessed by ssh-keygen but it is offered as the default file for | ||
413 | the private key. ssh(1) will read this file when a login attempt | ||
414 | is made. | ||
415 | |||
416 | ~/.ssh/id_dsa.pub | ||
417 | Contains the protocol version 2 DSA public key for | ||
418 | authentication. The contents of this file should be added to | ||
419 | ~/.ssh/authorized_keys on all machines where the user wishes to | ||
420 | log in using public key authentication. There is no need to keep | ||
421 | the contents of this file secret. | ||
422 | |||
423 | ~/.ssh/id_rsa | ||
424 | Contains the protocol version 2 RSA authentication identity of | ||
425 | the user. This file should not be readable by anyone but the | ||
426 | user. It is possible to specify a passphrase when generating the | ||
427 | key; that passphrase will be used to encrypt the private part of | ||
428 | this file using 128-bit AES. This file is not automatically | ||
429 | accessed by ssh-keygen but it is offered as the default file for | ||
430 | the private key. ssh(1) will read this file when a login attempt | ||
431 | is made. | ||
432 | |||
433 | ~/.ssh/id_rsa.pub | ||
434 | Contains the protocol version 2 RSA public key for | ||
435 | authentication. The contents of this file should be added to | ||
436 | ~/.ssh/authorized_keys on all machines where the user wishes to | ||
437 | log in using public key authentication. There is no need to keep | ||
438 | the contents of this file secret. | ||
439 | |||
440 | /etc/moduli | ||
441 | Contains Diffie-Hellman groups used for DH-GEX. The file format | ||
442 | is described in moduli(5). | ||
443 | |||
444 | SEE ALSO | ||
445 | ssh(1), ssh-add(1), ssh-agent(1), moduli(5), sshd(8) | ||
446 | |||
447 | The Secure Shell (SSH) Public Key File Format, RFC 4716, 2006. | ||
448 | |||
449 | AUTHORS | ||
450 | OpenSSH is a derivative of the original and free ssh 1.2.12 release by | ||
451 | Tatu Ylonen. Aaron Campbell, Bob Beck, Markus Friedl, Niels Provos, Theo | ||
452 | de Raadt and Dug Song removed many bugs, re-added newer features and | ||
453 | created OpenSSH. Markus Friedl contributed the support for SSH protocol | ||
454 | versions 1.5 and 2.0. | ||
455 | |||
456 | OpenBSD 4.8 August 4, 2010 OpenBSD 4.8 | ||