diff options
author | Colin Watson <cjwatson@debian.org> | 2012-09-06 19:11:34 +0100 |
---|---|---|
committer | Colin Watson <cjwatson@debian.org> | 2012-09-06 19:11:34 +0100 |
commit | 8b13b5bdc4f19bd52ee673104d66b71c21153b96 (patch) | |
tree | 833867a296a373e08233b2e1f549d4bcff79dda6 /ssh-keygen.0 | |
parent | 4eb0a532efe679917e07655721145c6882bdb4c7 (diff) | |
parent | b9bc38990c5eb5d99e28ca5af6d3491fd4a0060a (diff) |
Import 6.1p1 tarball
Diffstat (limited to 'ssh-keygen.0')
-rw-r--r-- | ssh-keygen.0 | 468 |
1 files changed, 468 insertions, 0 deletions
diff --git a/ssh-keygen.0 b/ssh-keygen.0 new file mode 100644 index 000000000..8f9fbd179 --- /dev/null +++ b/ssh-keygen.0 | |||
@@ -0,0 +1,468 @@ | |||
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 | [-J num_lines] [-j start_line] [-K checkpt] [-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 | ssh-keygen -A | ||
28 | |||
29 | DESCRIPTION | ||
30 | ssh-keygen generates, manages and converts authentication keys for | ||
31 | ssh(1). ssh-keygen can create RSA keys for use by SSH protocol version 1 | ||
32 | and DSA, ECDSA or RSA keys for use by SSH protocol version 2. The type | ||
33 | of key to be generated is specified with the -t option. If invoked | ||
34 | without any arguments, ssh-keygen will generate an RSA key for use in SSH | ||
35 | protocol 2 connections. | ||
36 | |||
37 | ssh-keygen is also used to generate groups for use in Diffie-Hellman | ||
38 | group exchange (DH-GEX). See the MODULI GENERATION section for details. | ||
39 | |||
40 | Normally each user wishing to use SSH with public key authentication runs | ||
41 | this once to create the authentication key in ~/.ssh/identity, | ||
42 | ~/.ssh/id_ecdsa, ~/.ssh/id_dsa or ~/.ssh/id_rsa. Additionally, the | ||
43 | system administrator may use this to generate host keys, as seen in | ||
44 | /etc/rc. | ||
45 | |||
46 | Normally this program generates the key and asks for a file in which to | ||
47 | store the private key. The public key is stored in a file with the same | ||
48 | name but ``.pub'' appended. The program also asks for a passphrase. The | ||
49 | passphrase may be empty to indicate no passphrase (host keys must have an | ||
50 | empty passphrase), or it may be a string of arbitrary length. A | ||
51 | passphrase is similar to a password, except it can be a phrase with a | ||
52 | series of words, punctuation, numbers, whitespace, or any string of | ||
53 | characters you want. Good passphrases are 10-30 characters long, are not | ||
54 | simple sentences or otherwise easily guessable (English prose has only | ||
55 | 1-2 bits of entropy per character, and provides very bad passphrases), | ||
56 | and contain a mix of upper and lowercase letters, numbers, and non- | ||
57 | alphanumeric characters. The passphrase can be changed later by using | ||
58 | the -p option. | ||
59 | |||
60 | There is no way to recover a lost passphrase. If the passphrase is lost | ||
61 | or forgotten, a new key must be generated and the corresponding public | ||
62 | key copied to other machines. | ||
63 | |||
64 | For RSA1 keys, there is also a comment field in the key file that is only | ||
65 | for convenience to the user to help identify the key. The comment can | ||
66 | tell what the key is for, or whatever is useful. The comment is | ||
67 | initialized to ``user@host'' when the key is created, but can be changed | ||
68 | using the -c option. | ||
69 | |||
70 | After a key is generated, instructions below detail where the keys should | ||
71 | be placed to be activated. | ||
72 | |||
73 | The options are as follows: | ||
74 | |||
75 | -A For each of the key types (rsa1, rsa, dsa and ecdsa) for which | ||
76 | host keys do not exist, generate the host keys with the default | ||
77 | key file path, an empty passphrase, default bits for the key | ||
78 | type, and default comment. This is used by /etc/rc to generate | ||
79 | new host keys. | ||
80 | |||
81 | -a trials | ||
82 | Specifies the number of primality tests to perform when screening | ||
83 | DH-GEX candidates using the -T command. | ||
84 | |||
85 | -B Show the bubblebabble digest of specified private or public key | ||
86 | file. | ||
87 | |||
88 | -b bits | ||
89 | Specifies the number of bits in the key to create. For RSA keys, | ||
90 | the minimum size is 768 bits and the default is 2048 bits. | ||
91 | Generally, 2048 bits is considered sufficient. DSA keys must be | ||
92 | exactly 1024 bits as specified by FIPS 186-2. For ECDSA keys, | ||
93 | the -b flag determines the key length by selecting from one of | ||
94 | three elliptic curve sizes: 256, 384 or 521 bits. Attempting to | ||
95 | use bit lengths other than these three values for ECDSA keys will | ||
96 | fail. | ||
97 | |||
98 | -C comment | ||
99 | Provides a new comment. | ||
100 | |||
101 | -c Requests changing the comment in the private and public key | ||
102 | files. This operation is only supported for RSA1 keys. The | ||
103 | program will prompt for the file containing the private keys, for | ||
104 | the passphrase if the key has one, and for the new comment. | ||
105 | |||
106 | -D pkcs11 | ||
107 | Download the RSA public keys provided by the PKCS#11 shared | ||
108 | library pkcs11. When used in combination with -s, this option | ||
109 | indicates that a CA key resides in a PKCS#11 token (see the | ||
110 | CERTIFICATES section for details). | ||
111 | |||
112 | -e This option will read a private or public OpenSSH key file and | ||
113 | print to stdout the key in one of the formats specified by the -m | ||
114 | option. The default export format is ``RFC4716''. This option | ||
115 | allows exporting OpenSSH keys for use by other programs, | ||
116 | including several commercial SSH implementations. | ||
117 | |||
118 | -F hostname | ||
119 | Search for the specified hostname in a known_hosts file, listing | ||
120 | any occurrences found. This option is useful to find hashed host | ||
121 | names or addresses and may also be used in conjunction with the | ||
122 | -H option to print found keys in a hashed format. | ||
123 | |||
124 | -f filename | ||
125 | Specifies the filename of the key file. | ||
126 | |||
127 | -G output_file | ||
128 | Generate candidate primes for DH-GEX. These primes must be | ||
129 | screened for safety (using the -T option) before use. | ||
130 | |||
131 | -g Use generic DNS format when printing fingerprint resource records | ||
132 | using the -r command. | ||
133 | |||
134 | -H Hash a known_hosts file. This replaces all hostnames and | ||
135 | addresses with hashed representations within the specified file; | ||
136 | the original content is moved to a file with a .old suffix. | ||
137 | These hashes may be used normally by ssh and sshd, but they do | ||
138 | not reveal identifying information should the file's contents be | ||
139 | disclosed. This option will not modify existing hashed hostnames | ||
140 | and is therefore safe to use on files that mix hashed and non- | ||
141 | hashed names. | ||
142 | |||
143 | -h When signing a key, create a host certificate instead of a user | ||
144 | certificate. Please see the CERTIFICATES section for details. | ||
145 | |||
146 | -I certificate_identity | ||
147 | Specify the key identity when signing a public key. Please see | ||
148 | the CERTIFICATES section for details. | ||
149 | |||
150 | -i This option will read an unencrypted private (or public) key file | ||
151 | in the format specified by the -m option and print an OpenSSH | ||
152 | compatible private (or public) key to stdout. | ||
153 | |||
154 | -J num_lines | ||
155 | Exit after screening the specified number of lines while | ||
156 | performing DH candidate screening using the -T option. | ||
157 | |||
158 | -j start_line | ||
159 | Start screening at the specified line number while performing DH | ||
160 | candidate screening using the -T option. | ||
161 | |||
162 | -K checkpt | ||
163 | Write the last line processed to the file checkpt while | ||
164 | performing DH candidate screening using the -T option. This will | ||
165 | be used to skip lines in the input file that have already been | ||
166 | processed if the job is restarted. This option allows importing | ||
167 | keys from other software, including several commercial SSH | ||
168 | implementations. The default import format is ``RFC4716''. | ||
169 | |||
170 | -L Prints the contents of a certificate. | ||
171 | |||
172 | -l Show fingerprint of specified public key file. Private RSA1 keys | ||
173 | are also supported. For RSA and DSA keys ssh-keygen tries to | ||
174 | find the matching public key file and prints its fingerprint. If | ||
175 | combined with -v, an ASCII art representation of the key is | ||
176 | supplied with the fingerprint. | ||
177 | |||
178 | -M memory | ||
179 | Specify the amount of memory to use (in megabytes) when | ||
180 | generating candidate moduli for DH-GEX. | ||
181 | |||
182 | -m key_format | ||
183 | Specify a key format for the -i (import) or -e (export) | ||
184 | conversion options. The supported key formats are: ``RFC4716'' | ||
185 | (RFC 4716/SSH2 public or private key), ``PKCS8'' (PEM PKCS8 | ||
186 | public key) or ``PEM'' (PEM public key). The default conversion | ||
187 | format is ``RFC4716''. | ||
188 | |||
189 | -N new_passphrase | ||
190 | Provides the new passphrase. | ||
191 | |||
192 | -n principals | ||
193 | Specify one or more principals (user or host names) to be | ||
194 | included in a certificate when signing a key. Multiple | ||
195 | principals may be specified, separated by commas. Please see the | ||
196 | CERTIFICATES section for details. | ||
197 | |||
198 | -O option | ||
199 | Specify a certificate option when signing a key. This option may | ||
200 | be specified multiple times. Please see the CERTIFICATES section | ||
201 | for details. The options that are valid for user certificates | ||
202 | are: | ||
203 | |||
204 | clear Clear all enabled permissions. This is useful for | ||
205 | clearing the default set of permissions so permissions | ||
206 | may be added individually. | ||
207 | |||
208 | force-command=command | ||
209 | Forces the execution of command instead of any shell or | ||
210 | command specified by the user when the certificate is | ||
211 | used for authentication. | ||
212 | |||
213 | no-agent-forwarding | ||
214 | Disable ssh-agent(1) forwarding (permitted by default). | ||
215 | |||
216 | no-port-forwarding | ||
217 | Disable port forwarding (permitted by default). | ||
218 | |||
219 | no-pty Disable PTY allocation (permitted by default). | ||
220 | |||
221 | no-user-rc | ||
222 | Disable execution of ~/.ssh/rc by sshd(8) (permitted by | ||
223 | default). | ||
224 | |||
225 | no-x11-forwarding | ||
226 | Disable X11 forwarding (permitted by default). | ||
227 | |||
228 | permit-agent-forwarding | ||
229 | Allows ssh-agent(1) forwarding. | ||
230 | |||
231 | permit-port-forwarding | ||
232 | Allows port forwarding. | ||
233 | |||
234 | permit-pty | ||
235 | Allows PTY allocation. | ||
236 | |||
237 | permit-user-rc | ||
238 | Allows execution of ~/.ssh/rc by sshd(8). | ||
239 | |||
240 | permit-x11-forwarding | ||
241 | Allows X11 forwarding. | ||
242 | |||
243 | source-address=address_list | ||
244 | Restrict the source addresses from which the certificate | ||
245 | is considered valid. The address_list is a comma- | ||
246 | separated list of one or more address/netmask pairs in | ||
247 | CIDR format. | ||
248 | |||
249 | At present, no options are valid for host keys. | ||
250 | |||
251 | -P passphrase | ||
252 | Provides the (old) passphrase. | ||
253 | |||
254 | -p Requests changing the passphrase of a private key file instead of | ||
255 | creating a new private key. The program will prompt for the file | ||
256 | containing the private key, for the old passphrase, and twice for | ||
257 | the new passphrase. | ||
258 | |||
259 | -q Silence ssh-keygen. | ||
260 | |||
261 | -R hostname | ||
262 | Removes all keys belonging to hostname from a known_hosts file. | ||
263 | This option is useful to delete hashed hosts (see the -H option | ||
264 | above). | ||
265 | |||
266 | -r hostname | ||
267 | Print the SSHFP fingerprint resource record named hostname for | ||
268 | the specified public key file. | ||
269 | |||
270 | -S start | ||
271 | Specify start point (in hex) when generating candidate moduli for | ||
272 | DH-GEX. | ||
273 | |||
274 | -s ca_key | ||
275 | Certify (sign) a public key using the specified CA key. Please | ||
276 | see the CERTIFICATES section for details. | ||
277 | |||
278 | -T output_file | ||
279 | Test DH group exchange candidate primes (generated using the -G | ||
280 | option) for safety. | ||
281 | |||
282 | -t type | ||
283 | Specifies the type of key to create. The possible values are | ||
284 | ``rsa1'' for protocol version 1 and ``dsa'', ``ecdsa'' or ``rsa'' | ||
285 | for protocol version 2. | ||
286 | |||
287 | -V validity_interval | ||
288 | Specify a validity interval when signing a certificate. A | ||
289 | validity interval may consist of a single time, indicating that | ||
290 | the certificate is valid beginning now and expiring at that time, | ||
291 | or may consist of two times separated by a colon to indicate an | ||
292 | explicit time interval. The start time may be specified as a | ||
293 | date in YYYYMMDD format, a time in YYYYMMDDHHMMSS format or a | ||
294 | relative time (to the current time) consisting of a minus sign | ||
295 | followed by a relative time in the format described in the TIME | ||
296 | FORMATS section of sshd_config(5). The end time may be specified | ||
297 | as a YYYYMMDD date, a YYYYMMDDHHMMSS time or a relative time | ||
298 | starting with a plus character. | ||
299 | |||
300 | For example: ``+52w1d'' (valid from now to 52 weeks and one day | ||
301 | from now), ``-4w:+4w'' (valid from four weeks ago to four weeks | ||
302 | from now), ``20100101123000:20110101123000'' (valid from 12:30 | ||
303 | PM, January 1st, 2010 to 12:30 PM, January 1st, 2011), | ||
304 | ``-1d:20110101'' (valid from yesterday to midnight, January 1st, | ||
305 | 2011). | ||
306 | |||
307 | -v Verbose mode. Causes ssh-keygen to print debugging messages | ||
308 | about its progress. This is helpful for debugging moduli | ||
309 | generation. Multiple -v options increase the verbosity. The | ||
310 | maximum is 3. | ||
311 | |||
312 | -W generator | ||
313 | Specify desired generator when testing candidate moduli for DH- | ||
314 | GEX. | ||
315 | |||
316 | -y This option will read a private OpenSSH format file and print an | ||
317 | OpenSSH public key to stdout. | ||
318 | |||
319 | -z serial_number | ||
320 | Specifies a serial number to be embedded in the certificate to | ||
321 | distinguish this certificate from others from the same CA. The | ||
322 | default serial number is zero. | ||
323 | |||
324 | MODULI GENERATION | ||
325 | ssh-keygen may be used to generate groups for the Diffie-Hellman Group | ||
326 | Exchange (DH-GEX) protocol. Generating these groups is a two-step | ||
327 | process: first, candidate primes are generated using a fast, but memory | ||
328 | intensive process. These candidate primes are then tested for | ||
329 | suitability (a CPU-intensive process). | ||
330 | |||
331 | Generation of primes is performed using the -G option. The desired | ||
332 | length of the primes may be specified by the -b option. For example: | ||
333 | |||
334 | # ssh-keygen -G moduli-2048.candidates -b 2048 | ||
335 | |||
336 | By default, the search for primes begins at a random point in the desired | ||
337 | length range. This may be overridden using the -S option, which | ||
338 | specifies a different start point (in hex). | ||
339 | |||
340 | Once a set of candidates have been generated, they must be screened for | ||
341 | suitability. This may be performed using the -T option. In this mode | ||
342 | ssh-keygen will read candidates from standard input (or a file specified | ||
343 | using the -f option). For example: | ||
344 | |||
345 | # ssh-keygen -T moduli-2048 -f moduli-2048.candidates | ||
346 | |||
347 | By default, each candidate will be subjected to 100 primality tests. | ||
348 | This may be overridden using the -a option. The DH generator value will | ||
349 | be chosen automatically for the prime under consideration. If a specific | ||
350 | generator is desired, it may be requested using the -W option. Valid | ||
351 | generator values are 2, 3, and 5. | ||
352 | |||
353 | Screened DH groups may be installed in /etc/moduli. It is important that | ||
354 | this file contains moduli of a range of bit lengths and that both ends of | ||
355 | a connection share common moduli. | ||
356 | |||
357 | CERTIFICATES | ||
358 | ssh-keygen supports signing of keys to produce certificates that may be | ||
359 | used for user or host authentication. Certificates consist of a public | ||
360 | key, some identity information, zero or more principal (user or host) | ||
361 | names and a set of options that are signed by a Certification Authority | ||
362 | (CA) key. Clients or servers may then trust only the CA key and verify | ||
363 | its signature on a certificate rather than trusting many user/host keys. | ||
364 | Note that OpenSSH certificates are a different, and much simpler, format | ||
365 | to the X.509 certificates used in ssl(8). | ||
366 | |||
367 | ssh-keygen supports two types of certificates: user and host. User | ||
368 | certificates authenticate users to servers, whereas host certificates | ||
369 | authenticate server hosts to users. To generate a user certificate: | ||
370 | |||
371 | $ ssh-keygen -s /path/to/ca_key -I key_id /path/to/user_key.pub | ||
372 | |||
373 | The resultant certificate will be placed in /path/to/user_key-cert.pub. | ||
374 | A host certificate requires the -h option: | ||
375 | |||
376 | $ ssh-keygen -s /path/to/ca_key -I key_id -h /path/to/host_key.pub | ||
377 | |||
378 | The host certificate will be output to /path/to/host_key-cert.pub. | ||
379 | |||
380 | It is possible to sign using a CA key stored in a PKCS#11 token by | ||
381 | providing the token library using -D and identifying the CA key by | ||
382 | providing its public half as an argument to -s: | ||
383 | |||
384 | $ ssh-keygen -s ca_key.pub -D libpkcs11.so -I key_id host_key.pub | ||
385 | |||
386 | In all cases, key_id is a "key identifier" that is logged by the server | ||
387 | when the certificate is used for authentication. | ||
388 | |||
389 | Certificates may be limited to be valid for a set of principal | ||
390 | (user/host) names. By default, generated certificates are valid for all | ||
391 | users or hosts. To generate a certificate for a specified set of | ||
392 | principals: | ||
393 | |||
394 | $ ssh-keygen -s ca_key -I key_id -n user1,user2 user_key.pub | ||
395 | $ ssh-keygen -s ca_key -I key_id -h -n host.domain user_key.pub | ||
396 | |||
397 | Additional limitations on the validity and use of user certificates may | ||
398 | be specified through certificate options. A certificate option may | ||
399 | disable features of the SSH session, may be valid only when presented | ||
400 | from particular source addresses or may force the use of a specific | ||
401 | command. For a list of valid certificate options, see the documentation | ||
402 | for the -O option above. | ||
403 | |||
404 | Finally, certificates may be defined with a validity lifetime. The -V | ||
405 | option allows specification of certificate start and end times. A | ||
406 | certificate that is presented at a time outside this range will not be | ||
407 | considered valid. By default, certificates have a maximum validity | ||
408 | interval. | ||
409 | |||
410 | For certificates to be used for user or host authentication, the CA | ||
411 | public key must be trusted by sshd(8) or ssh(1). Please refer to those | ||
412 | manual pages for details. | ||
413 | |||
414 | FILES | ||
415 | ~/.ssh/identity | ||
416 | Contains the protocol version 1 RSA authentication identity of | ||
417 | the user. This file should not be readable by anyone but the | ||
418 | user. It is possible to specify a passphrase when generating the | ||
419 | key; that passphrase will be used to encrypt the private part of | ||
420 | this file using 3DES. This file is not automatically accessed by | ||
421 | ssh-keygen but it is offered as the default file for the private | ||
422 | key. ssh(1) will read this file when a login attempt is made. | ||
423 | |||
424 | ~/.ssh/identity.pub | ||
425 | Contains the protocol version 1 RSA public key for | ||
426 | authentication. The contents of this file should be added to | ||
427 | ~/.ssh/authorized_keys on all machines where the user wishes to | ||
428 | log in using RSA authentication. There is no need to keep the | ||
429 | contents of this file secret. | ||
430 | |||
431 | ~/.ssh/id_dsa | ||
432 | ~/.ssh/id_ecdsa | ||
433 | ~/.ssh/id_rsa | ||
434 | Contains the protocol version 2 DSA, ECDSA or RSA authentication | ||
435 | identity of the user. This file should not be readable by anyone | ||
436 | but the user. It is possible to specify a passphrase when | ||
437 | generating the key; that passphrase will be used to encrypt the | ||
438 | private part of this file using 128-bit AES. This file is not | ||
439 | automatically accessed by ssh-keygen but it is offered as the | ||
440 | default file for the private key. ssh(1) will read this file | ||
441 | when a login attempt is made. | ||
442 | |||
443 | ~/.ssh/id_dsa.pub | ||
444 | ~/.ssh/id_ecdsa.pub | ||
445 | ~/.ssh/id_rsa.pub | ||
446 | Contains the protocol version 2 DSA, ECDSA or RSA public key for | ||
447 | authentication. The contents of this file should be added to | ||
448 | ~/.ssh/authorized_keys on all machines where the user wishes to | ||
449 | log in using public key authentication. There is no need to keep | ||
450 | the contents of this file secret. | ||
451 | |||
452 | /etc/moduli | ||
453 | Contains Diffie-Hellman groups used for DH-GEX. The file format | ||
454 | is described in moduli(5). | ||
455 | |||
456 | SEE ALSO | ||
457 | ssh(1), ssh-add(1), ssh-agent(1), moduli(5), sshd(8) | ||
458 | |||
459 | The Secure Shell (SSH) Public Key File Format, RFC 4716, 2006. | ||
460 | |||
461 | AUTHORS | ||
462 | OpenSSH is a derivative of the original and free ssh 1.2.12 release by | ||
463 | Tatu Ylonen. Aaron Campbell, Bob Beck, Markus Friedl, Niels Provos, Theo | ||
464 | de Raadt and Dug Song removed many bugs, re-added newer features and | ||
465 | created OpenSSH. Markus Friedl contributed the support for SSH protocol | ||
466 | versions 1.5 and 2.0. | ||
467 | |||
468 | OpenBSD 5.2 July 6, 2012 OpenBSD 5.2 | ||