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1 | SSH-KEYGEN(1) General Commands Manual SSH-KEYGEN(1) | ||
2 | |||
3 | NAME | ||
4 | ssh-keygen M-bM-^@M-^S authentication key generation, management and conversion | ||
5 | |||
6 | SYNOPSIS | ||
7 | ssh-keygen [-q] [-b bits] [-t dsa | ecdsa | ed25519 | rsa] | ||
8 | [-N new_passphrase] [-C comment] [-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 [-v] [-E fingerprint_hash] [-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 rounds] [-J num_lines] | ||
23 | [-j start_line] [-K checkpt] [-W generator] | ||
24 | ssh-keygen -s ca_key -I certificate_identity [-h] [-U] | ||
25 | [-D pkcs11_provider] [-n principals] [-O option] | ||
26 | [-V validity_interval] [-z serial_number] file ... | ||
27 | ssh-keygen -L [-f input_keyfile] | ||
28 | ssh-keygen -A [-f prefix_path] | ||
29 | ssh-keygen -k -f krl_file [-u] [-s ca_public] [-z version_number] | ||
30 | file ... | ||
31 | ssh-keygen -Q -f krl_file file ... | ||
32 | |||
33 | DESCRIPTION | ||
34 | ssh-keygen generates, manages and converts authentication keys for | ||
35 | ssh(1). ssh-keygen can create keys for use by SSH protocol version 2. | ||
36 | |||
37 | The type of key to be generated is specified with the -t option. If | ||
38 | invoked without any arguments, ssh-keygen will generate an RSA key. | ||
39 | |||
40 | ssh-keygen is also used to generate groups for use in Diffie-Hellman | ||
41 | group exchange (DH-GEX). See the MODULI GENERATION section for details. | ||
42 | |||
43 | Finally, ssh-keygen can be used to generate and update Key Revocation | ||
44 | Lists, and to test whether given keys have been revoked by one. See the | ||
45 | KEY REVOCATION LISTS section for details. | ||
46 | |||
47 | Normally each user wishing to use SSH with public key authentication runs | ||
48 | this once to create the authentication key in ~/.ssh/id_dsa, | ||
49 | ~/.ssh/id_ecdsa, ~/.ssh/id_ed25519 or ~/.ssh/id_rsa. Additionally, the | ||
50 | system administrator may use this to generate host keys, as seen in | ||
51 | /etc/rc. | ||
52 | |||
53 | Normally this program generates the key and asks for a file in which to | ||
54 | store the private key. The public key is stored in a file with the same | ||
55 | name but M-bM-^@M-^\.pubM-bM-^@M-^] appended. The program also asks for a passphrase. The | ||
56 | passphrase may be empty to indicate no passphrase (host keys must have an | ||
57 | empty passphrase), or it may be a string of arbitrary length. A | ||
58 | passphrase is similar to a password, except it can be a phrase with a | ||
59 | series of words, punctuation, numbers, whitespace, or any string of | ||
60 | characters you want. Good passphrases are 10-30 characters long, are not | ||
61 | simple sentences or otherwise easily guessable (English prose has only | ||
62 | 1-2 bits of entropy per character, and provides very bad passphrases), | ||
63 | and contain a mix of upper and lowercase letters, numbers, and non- | ||
64 | alphanumeric characters. The passphrase can be changed later by using | ||
65 | the -p option. | ||
66 | |||
67 | There is no way to recover a lost passphrase. If the passphrase is lost | ||
68 | or forgotten, a new key must be generated and the corresponding public | ||
69 | key copied to other machines. | ||
70 | |||
71 | For keys stored in the newer OpenSSH format, there is also a comment | ||
72 | field in the key file that is only for convenience to the user to help | ||
73 | identify the key. The comment can tell what the key is for, or whatever | ||
74 | is useful. The comment is initialized to M-bM-^@M-^\user@hostM-bM-^@M-^] when the key is | ||
75 | created, but can be changed using the -c option. | ||
76 | |||
77 | After a key is generated, instructions below detail where the keys should | ||
78 | be placed to be activated. | ||
79 | |||
80 | The options are as follows: | ||
81 | |||
82 | -A For each of the key types (rsa, dsa, ecdsa and ed25519) for which | ||
83 | host keys do not exist, generate the host keys with the default | ||
84 | key file path, an empty passphrase, default bits for the key | ||
85 | type, and default comment. If -f has also been specified, its | ||
86 | argument is used as a prefix to the default path for the | ||
87 | resulting host key files. This is used by /etc/rc to generate | ||
88 | new host keys. | ||
89 | |||
90 | -a rounds | ||
91 | When saving a new-format private key (i.e. an ed25519 key or when | ||
92 | the -o flag is set), this option specifies the number of KDF (key | ||
93 | derivation function) rounds used. Higher numbers result in | ||
94 | slower passphrase verification and increased resistance to brute- | ||
95 | force password cracking (should the keys be stolen). | ||
96 | |||
97 | When screening DH-GEX candidates (using the -T command). This | ||
98 | option specifies the number of primality tests to perform. | ||
99 | |||
100 | -B Show the bubblebabble digest of specified private or public key | ||
101 | file. | ||
102 | |||
103 | -b bits | ||
104 | Specifies the number of bits in the key to create. For RSA keys, | ||
105 | the minimum size is 1024 bits and the default is 2048 bits. | ||
106 | Generally, 2048 bits is considered sufficient. DSA keys must be | ||
107 | exactly 1024 bits as specified by FIPS 186-2. For ECDSA keys, | ||
108 | the -b flag determines the key length by selecting from one of | ||
109 | three elliptic curve sizes: 256, 384 or 521 bits. Attempting to | ||
110 | use bit lengths other than these three values for ECDSA keys will | ||
111 | fail. Ed25519 keys have a fixed length and the -b flag will be | ||
112 | ignored. | ||
113 | |||
114 | -C comment | ||
115 | Provides a new comment. | ||
116 | |||
117 | -c Requests changing the comment in the private and public key | ||
118 | files. This operation is only supported for keys stored in the | ||
119 | newer OpenSSH format. The program will prompt for the file | ||
120 | containing the private keys, for the passphrase if the key has | ||
121 | one, and for the new comment. | ||
122 | |||
123 | -D pkcs11 | ||
124 | Download the RSA public keys provided by the PKCS#11 shared | ||
125 | library pkcs11. When used in combination with -s, this option | ||
126 | indicates that a CA key resides in a PKCS#11 token (see the | ||
127 | CERTIFICATES section for details). | ||
128 | |||
129 | -E fingerprint_hash | ||
130 | Specifies the hash algorithm used when displaying key | ||
131 | fingerprints. Valid options are: M-bM-^@M-^\md5M-bM-^@M-^] and M-bM-^@M-^\sha256M-bM-^@M-^]. The | ||
132 | default is M-bM-^@M-^\sha256M-bM-^@M-^]. | ||
133 | |||
134 | -e This option will read a private or public OpenSSH key file and | ||
135 | print to stdout the key in one of the formats specified by the -m | ||
136 | option. The default export format is M-bM-^@M-^\RFC4716M-bM-^@M-^]. This option | ||
137 | allows exporting OpenSSH keys for use by other programs, | ||
138 | including several commercial SSH implementations. | ||
139 | |||
140 | -F hostname | ||
141 | Search for the specified hostname in a known_hosts file, listing | ||
142 | any occurrences found. This option is useful to find hashed host | ||
143 | names or addresses and may also be used in conjunction with the | ||
144 | -H option to print found keys in a hashed format. | ||
145 | |||
146 | -f filename | ||
147 | Specifies the filename of the key file. | ||
148 | |||
149 | -G output_file | ||
150 | Generate candidate primes for DH-GEX. These primes must be | ||
151 | screened for safety (using the -T option) before use. | ||
152 | |||
153 | -g Use generic DNS format when printing fingerprint resource records | ||
154 | using the -r command. | ||
155 | |||
156 | -H Hash a known_hosts file. This replaces all hostnames and | ||
157 | addresses with hashed representations within the specified file; | ||
158 | the original content is moved to a file with a .old suffix. | ||
159 | These hashes may be used normally by ssh and sshd, but they do | ||
160 | not reveal identifying information should the file's contents be | ||
161 | disclosed. This option will not modify existing hashed hostnames | ||
162 | and is therefore safe to use on files that mix hashed and non- | ||
163 | hashed names. | ||
164 | |||
165 | -h When signing a key, create a host certificate instead of a user | ||
166 | certificate. Please see the CERTIFICATES section for details. | ||
167 | |||
168 | -I certificate_identity | ||
169 | Specify the key identity when signing a public key. Please see | ||
170 | the CERTIFICATES section for details. | ||
171 | |||
172 | -i This option will read an unencrypted private (or public) key file | ||
173 | in the format specified by the -m option and print an OpenSSH | ||
174 | compatible private (or public) key to stdout. This option allows | ||
175 | importing keys from other software, including several commercial | ||
176 | SSH implementations. The default import format is M-bM-^@M-^\RFC4716M-bM-^@M-^]. | ||
177 | |||
178 | -J num_lines | ||
179 | Exit after screening the specified number of lines while | ||
180 | performing DH candidate screening using the -T option. | ||
181 | |||
182 | -j start_line | ||
183 | Start screening at the specified line number while performing DH | ||
184 | candidate screening using the -T option. | ||
185 | |||
186 | -K checkpt | ||
187 | Write the last line processed to the file checkpt while | ||
188 | performing DH candidate screening using the -T option. This will | ||
189 | be used to skip lines in the input file that have already been | ||
190 | processed if the job is restarted. | ||
191 | |||
192 | -k Generate a KRL file. In this mode, ssh-keygen will generate a | ||
193 | KRL file at the location specified via the -f flag that revokes | ||
194 | every key or certificate presented on the command line. | ||
195 | Keys/certificates to be revoked may be specified by public key | ||
196 | file or using the format described in the KEY REVOCATION LISTS | ||
197 | section. | ||
198 | |||
199 | -L Prints the contents of one or more certificates. | ||
200 | |||
201 | -l Show fingerprint of specified public key file. For RSA and DSA | ||
202 | keys ssh-keygen tries to find the matching public key file and | ||
203 | prints its fingerprint. If combined with -v, a visual ASCII art | ||
204 | representation of the key is supplied with the fingerprint. | ||
205 | |||
206 | -M memory | ||
207 | Specify the amount of memory to use (in megabytes) when | ||
208 | generating candidate moduli for DH-GEX. | ||
209 | |||
210 | -m key_format | ||
211 | Specify a key format for the -i (import) or -e (export) | ||
212 | conversion options. The supported key formats are: M-bM-^@M-^\RFC4716M-bM-^@M-^] | ||
213 | (RFC 4716/SSH2 public or private key), M-bM-^@M-^\PKCS8M-bM-^@M-^] (PEM PKCS8 public | ||
214 | key) or M-bM-^@M-^\PEMM-bM-^@M-^] (PEM public key). The default conversion format is | ||
215 | M-bM-^@M-^\RFC4716M-bM-^@M-^]. | ||
216 | |||
217 | -N new_passphrase | ||
218 | Provides the new passphrase. | ||
219 | |||
220 | -n principals | ||
221 | Specify one or more principals (user or host names) to be | ||
222 | included in a certificate when signing a key. Multiple | ||
223 | principals may be specified, separated by commas. Please see the | ||
224 | CERTIFICATES section for details. | ||
225 | |||
226 | -O option | ||
227 | Specify a certificate option when signing a key. This option may | ||
228 | be specified multiple times. See also the CERTIFICATES section | ||
229 | for further details. The options that are valid for user | ||
230 | certificates are: | ||
231 | |||
232 | clear Clear all enabled permissions. This is useful for | ||
233 | clearing the default set of permissions so permissions | ||
234 | may be added individually. | ||
235 | |||
236 | critical:name[=contents] | ||
237 | extension:name[=contents] | ||
238 | Includes an arbitrary certificate critical option or | ||
239 | extension. The specified name should include a domain | ||
240 | suffix, e.g. M-bM-^@M-^\name@example.comM-bM-^@M-^]. If contents is | ||
241 | specified then it is included as the contents of the | ||
242 | extension/option encoded as a string, otherwise the | ||
243 | extension/option is created with no contents (usually | ||
244 | indicating a flag). Extensions may be ignored by a | ||
245 | client or server that does not recognise them, whereas | ||
246 | unknown critical options will cause the certificate to be | ||
247 | refused. | ||
248 | |||
249 | At present, no standard options are valid for host keys. | ||
250 | |||
251 | force-command=command | ||
252 | Forces the execution of command instead of any shell or | ||
253 | command specified by the user when the certificate is | ||
254 | used for authentication. | ||
255 | |||
256 | no-agent-forwarding | ||
257 | Disable ssh-agent(1) forwarding (permitted by default). | ||
258 | |||
259 | no-port-forwarding | ||
260 | Disable port forwarding (permitted by default). | ||
261 | |||
262 | no-pty Disable PTY allocation (permitted by default). | ||
263 | |||
264 | no-user-rc | ||
265 | Disable execution of ~/.ssh/rc by sshd(8) (permitted by | ||
266 | default). | ||
267 | |||
268 | no-x11-forwarding | ||
269 | Disable X11 forwarding (permitted by default). | ||
270 | |||
271 | permit-agent-forwarding | ||
272 | Allows ssh-agent(1) forwarding. | ||
273 | |||
274 | permit-port-forwarding | ||
275 | Allows port forwarding. | ||
276 | |||
277 | permit-pty | ||
278 | Allows PTY allocation. | ||
279 | |||
280 | permit-user-rc | ||
281 | Allows execution of ~/.ssh/rc by sshd(8). | ||
282 | |||
283 | permit-x11-forwarding | ||
284 | Allows X11 forwarding. | ||
285 | |||
286 | source-address=address_list | ||
287 | Restrict the source addresses from which the certificate | ||
288 | is considered valid. The address_list is a comma- | ||
289 | separated list of one or more address/netmask pairs in | ||
290 | CIDR format. | ||
291 | |||
292 | -o Causes ssh-keygen to save private keys using the new OpenSSH | ||
293 | format rather than the more compatible PEM format. The new | ||
294 | format has increased resistance to brute-force password cracking | ||
295 | but is not supported by versions of OpenSSH prior to 6.5. | ||
296 | Ed25519 keys always use the new private key format. | ||
297 | |||
298 | -P passphrase | ||
299 | Provides the (old) passphrase. | ||
300 | |||
301 | -p Requests changing the passphrase of a private key file instead of | ||
302 | creating a new private key. The program will prompt for the file | ||
303 | containing the private key, for the old passphrase, and twice for | ||
304 | the new passphrase. | ||
305 | |||
306 | -Q Test whether keys have been revoked in a KRL. | ||
307 | |||
308 | -q Silence ssh-keygen. | ||
309 | |||
310 | -R hostname | ||
311 | Removes all keys belonging to hostname from a known_hosts file. | ||
312 | This option is useful to delete hashed hosts (see the -H option | ||
313 | above). | ||
314 | |||
315 | -r hostname | ||
316 | Print the SSHFP fingerprint resource record named hostname for | ||
317 | the specified public key file. | ||
318 | |||
319 | -S start | ||
320 | Specify start point (in hex) when generating candidate moduli for | ||
321 | DH-GEX. | ||
322 | |||
323 | -s ca_key | ||
324 | Certify (sign) a public key using the specified CA key. Please | ||
325 | see the CERTIFICATES section for details. | ||
326 | |||
327 | When generating a KRL, -s specifies a path to a CA public key | ||
328 | file used to revoke certificates directly by key ID or serial | ||
329 | number. See the KEY REVOCATION LISTS section for details. | ||
330 | |||
331 | -T output_file | ||
332 | Test DH group exchange candidate primes (generated using the -G | ||
333 | option) for safety. | ||
334 | |||
335 | -t dsa | ecdsa | ed25519 | rsa | ||
336 | Specifies the type of key to create. The possible values are | ||
337 | M-bM-^@M-^\dsaM-bM-^@M-^], M-bM-^@M-^\ecdsaM-bM-^@M-^], M-bM-^@M-^\ed25519M-bM-^@M-^], or M-bM-^@M-^\rsaM-bM-^@M-^]. | ||
338 | |||
339 | -U When used in combination with -s, this option indicates that a CA | ||
340 | key resides in a ssh-agent(1). See the CERTIFICATES section for | ||
341 | more information. | ||
342 | |||
343 | -u Update a KRL. When specified with -k, keys listed via the | ||
344 | command line are added to the existing KRL rather than a new KRL | ||
345 | being created. | ||
346 | |||
347 | -V validity_interval | ||
348 | Specify a validity interval when signing a certificate. A | ||
349 | validity interval may consist of a single time, indicating that | ||
350 | the certificate is valid beginning now and expiring at that time, | ||
351 | or may consist of two times separated by a colon to indicate an | ||
352 | explicit time interval. The start time may be specified as a | ||
353 | date in YYYYMMDD format, a time in YYYYMMDDHHMMSS format or a | ||
354 | relative time (to the current time) consisting of a minus sign | ||
355 | followed by a relative time in the format described in the TIME | ||
356 | FORMATS section of sshd_config(5). The end time may be specified | ||
357 | as a YYYYMMDD date, a YYYYMMDDHHMMSS time or a relative time | ||
358 | starting with a plus character. | ||
359 | |||
360 | For example: M-bM-^@M-^\+52w1dM-bM-^@M-^] (valid from now to 52 weeks and one day | ||
361 | from now), M-bM-^@M-^\-4w:+4wM-bM-^@M-^] (valid from four weeks ago to four weeks | ||
362 | from now), M-bM-^@M-^\20100101123000:20110101123000M-bM-^@M-^] (valid from 12:30 PM, | ||
363 | January 1st, 2010 to 12:30 PM, January 1st, 2011), M-bM-^@M-^\-1d:20110101M-bM-^@M-^] | ||
364 | (valid from yesterday to midnight, January 1st, 2011). | ||
365 | |||
366 | -v Verbose mode. Causes ssh-keygen to print debugging messages | ||
367 | about its progress. This is helpful for debugging moduli | ||
368 | generation. Multiple -v options increase the verbosity. The | ||
369 | maximum is 3. | ||
370 | |||
371 | -W generator | ||
372 | Specify desired generator when testing candidate moduli for DH- | ||
373 | GEX. | ||
374 | |||
375 | -y This option will read a private OpenSSH format file and print an | ||
376 | OpenSSH public key to stdout. | ||
377 | |||
378 | -z serial_number | ||
379 | Specifies a serial number to be embedded in the certificate to | ||
380 | distinguish this certificate from others from the same CA. The | ||
381 | default serial number is zero. | ||
382 | |||
383 | When generating a KRL, the -z flag is used to specify a KRL | ||
384 | version number. | ||
385 | |||
386 | MODULI GENERATION | ||
387 | ssh-keygen may be used to generate groups for the Diffie-Hellman Group | ||
388 | Exchange (DH-GEX) protocol. Generating these groups is a two-step | ||
389 | process: first, candidate primes are generated using a fast, but memory | ||
390 | intensive process. These candidate primes are then tested for | ||
391 | suitability (a CPU-intensive process). | ||
392 | |||
393 | Generation of primes is performed using the -G option. The desired | ||
394 | length of the primes may be specified by the -b option. For example: | ||
395 | |||
396 | # ssh-keygen -G moduli-2048.candidates -b 2048 | ||
397 | |||
398 | By default, the search for primes begins at a random point in the desired | ||
399 | length range. This may be overridden using the -S option, which | ||
400 | specifies a different start point (in hex). | ||
401 | |||
402 | Once a set of candidates have been generated, they must be screened for | ||
403 | suitability. This may be performed using the -T option. In this mode | ||
404 | ssh-keygen will read candidates from standard input (or a file specified | ||
405 | using the -f option). For example: | ||
406 | |||
407 | # ssh-keygen -T moduli-2048 -f moduli-2048.candidates | ||
408 | |||
409 | By default, each candidate will be subjected to 100 primality tests. | ||
410 | This may be overridden using the -a option. The DH generator value will | ||
411 | be chosen automatically for the prime under consideration. If a specific | ||
412 | generator is desired, it may be requested using the -W option. Valid | ||
413 | generator values are 2, 3, and 5. | ||
414 | |||
415 | Screened DH groups may be installed in /etc/moduli. It is important that | ||
416 | this file contains moduli of a range of bit lengths and that both ends of | ||
417 | a connection share common moduli. | ||
418 | |||
419 | CERTIFICATES | ||
420 | ssh-keygen supports signing of keys to produce certificates that may be | ||
421 | used for user or host authentication. Certificates consist of a public | ||
422 | key, some identity information, zero or more principal (user or host) | ||
423 | names and a set of options that are signed by a Certification Authority | ||
424 | (CA) key. Clients or servers may then trust only the CA key and verify | ||
425 | its signature on a certificate rather than trusting many user/host keys. | ||
426 | Note that OpenSSH certificates are a different, and much simpler, format | ||
427 | to the X.509 certificates used in ssl(8). | ||
428 | |||
429 | ssh-keygen supports two types of certificates: user and host. User | ||
430 | certificates authenticate users to servers, whereas host certificates | ||
431 | authenticate server hosts to users. To generate a user certificate: | ||
432 | |||
433 | $ ssh-keygen -s /path/to/ca_key -I key_id /path/to/user_key.pub | ||
434 | |||
435 | The resultant certificate will be placed in /path/to/user_key-cert.pub. | ||
436 | A host certificate requires the -h option: | ||
437 | |||
438 | $ ssh-keygen -s /path/to/ca_key -I key_id -h /path/to/host_key.pub | ||
439 | |||
440 | The host certificate will be output to /path/to/host_key-cert.pub. | ||
441 | |||
442 | It is possible to sign using a CA key stored in a PKCS#11 token by | ||
443 | providing the token library using -D and identifying the CA key by | ||
444 | providing its public half as an argument to -s: | ||
445 | |||
446 | $ ssh-keygen -s ca_key.pub -D libpkcs11.so -I key_id user_key.pub | ||
447 | |||
448 | Similarly, it is possible for the CA key to be hosted in a ssh-agent(1). | ||
449 | This is indicated by the -U flag and, again, the CA key must be | ||
450 | identified by its public half. | ||
451 | |||
452 | $ ssh-keygen -Us ca_key.pub -I key_id user_key.pub | ||
453 | |||
454 | In all cases, key_id is a "key identifier" that is logged by the server | ||
455 | when the certificate is used for authentication. | ||
456 | |||
457 | Certificates may be limited to be valid for a set of principal | ||
458 | (user/host) names. By default, generated certificates are valid for all | ||
459 | users or hosts. To generate a certificate for a specified set of | ||
460 | principals: | ||
461 | |||
462 | $ ssh-keygen -s ca_key -I key_id -n user1,user2 user_key.pub | ||
463 | $ ssh-keygen -s ca_key -I key_id -h -n host.domain host_key.pub | ||
464 | |||
465 | Additional limitations on the validity and use of user certificates may | ||
466 | be specified through certificate options. A certificate option may | ||
467 | disable features of the SSH session, may be valid only when presented | ||
468 | from particular source addresses or may force the use of a specific | ||
469 | command. For a list of valid certificate options, see the documentation | ||
470 | for the -O option above. | ||
471 | |||
472 | Finally, certificates may be defined with a validity lifetime. The -V | ||
473 | option allows specification of certificate start and end times. A | ||
474 | certificate that is presented at a time outside this range will not be | ||
475 | considered valid. By default, certificates are valid from UNIX Epoch to | ||
476 | the distant future. | ||
477 | |||
478 | For certificates to be used for user or host authentication, the CA | ||
479 | public key must be trusted by sshd(8) or ssh(1). Please refer to those | ||
480 | manual pages for details. | ||
481 | |||
482 | KEY REVOCATION LISTS | ||
483 | ssh-keygen is able to manage OpenSSH format Key Revocation Lists (KRLs). | ||
484 | These binary files specify keys or certificates to be revoked using a | ||
485 | compact format, taking as little as one bit per certificate if they are | ||
486 | being revoked by serial number. | ||
487 | |||
488 | KRLs may be generated using the -k flag. This option reads one or more | ||
489 | files from the command line and generates a new KRL. The files may | ||
490 | either contain a KRL specification (see below) or public keys, listed one | ||
491 | per line. Plain public keys are revoked by listing their hash or | ||
492 | contents in the KRL and certificates revoked by serial number or key ID | ||
493 | (if the serial is zero or not available). | ||
494 | |||
495 | Revoking keys using a KRL specification offers explicit control over the | ||
496 | types of record used to revoke keys and may be used to directly revoke | ||
497 | certificates by serial number or key ID without having the complete | ||
498 | original certificate on hand. A KRL specification consists of lines | ||
499 | containing one of the following directives followed by a colon and some | ||
500 | directive-specific information. | ||
501 | |||
502 | serial: serial_number[-serial_number] | ||
503 | Revokes a certificate with the specified serial number. Serial | ||
504 | numbers are 64-bit values, not including zero and may be | ||
505 | expressed in decimal, hex or octal. If two serial numbers are | ||
506 | specified separated by a hyphen, then the range of serial numbers | ||
507 | including and between each is revoked. The CA key must have been | ||
508 | specified on the ssh-keygen command line using the -s option. | ||
509 | |||
510 | id: key_id | ||
511 | Revokes a certificate with the specified key ID string. The CA | ||
512 | key must have been specified on the ssh-keygen command line using | ||
513 | the -s option. | ||
514 | |||
515 | key: public_key | ||
516 | Revokes the specified key. If a certificate is listed, then it | ||
517 | is revoked as a plain public key. | ||
518 | |||
519 | sha1: public_key | ||
520 | Revokes the specified key by its SHA1 hash. | ||
521 | |||
522 | KRLs may be updated using the -u flag in addition to -k. When this | ||
523 | option is specified, keys listed via the command line are merged into the | ||
524 | KRL, adding to those already there. | ||
525 | |||
526 | It is also possible, given a KRL, to test whether it revokes a particular | ||
527 | key (or keys). The -Q flag will query an existing KRL, testing each key | ||
528 | specified on the command line. If any key listed on the command line has | ||
529 | been revoked (or an error encountered) then ssh-keygen will exit with a | ||
530 | non-zero exit status. A zero exit status will only be returned if no key | ||
531 | was revoked. | ||
532 | |||
533 | FILES | ||
534 | ~/.ssh/id_dsa | ||
535 | ~/.ssh/id_ecdsa | ||
536 | ~/.ssh/id_ed25519 | ||
537 | ~/.ssh/id_rsa | ||
538 | Contains the DSA, ECDSA, Ed25519 or RSA authentication identity | ||
539 | of the user. This file should not be readable by anyone but the | ||
540 | user. It is possible to specify a passphrase when generating the | ||
541 | key; that passphrase will be used to encrypt the private part of | ||
542 | this file using 128-bit AES. This file is not automatically | ||
543 | accessed by ssh-keygen but it is offered as the default file for | ||
544 | the private key. ssh(1) will read this file when a login attempt | ||
545 | is made. | ||
546 | |||
547 | ~/.ssh/id_dsa.pub | ||
548 | ~/.ssh/id_ecdsa.pub | ||
549 | ~/.ssh/id_ed25519.pub | ||
550 | ~/.ssh/id_rsa.pub | ||
551 | Contains the DSA, ECDSA, Ed25519 or RSA public key for | ||
552 | authentication. The contents of this file should be added to | ||
553 | ~/.ssh/authorized_keys on all machines where the user wishes to | ||
554 | log in using public key authentication. There is no need to keep | ||
555 | the contents of this file secret. | ||
556 | |||
557 | /etc/moduli | ||
558 | Contains Diffie-Hellman groups used for DH-GEX. The file format | ||
559 | is described in moduli(5). | ||
560 | |||
561 | SEE ALSO | ||
562 | ssh(1), ssh-add(1), ssh-agent(1), moduli(5), sshd(8) | ||
563 | |||
564 | The Secure Shell (SSH) Public Key File Format, RFC 4716, 2006. | ||
565 | |||
566 | AUTHORS | ||
567 | OpenSSH is a derivative of the original and free ssh 1.2.12 release by | ||
568 | Tatu Ylonen. Aaron Campbell, Bob Beck, Markus Friedl, Niels Provos, Theo | ||
569 | de Raadt and Dug Song removed many bugs, re-added newer features and | ||
570 | created OpenSSH. Markus Friedl contributed the support for SSH protocol | ||
571 | versions 1.5 and 2.0. | ||
572 | |||
573 | OpenBSD 6.2 July 8, 2017 OpenBSD 6.2 | ||