Annotation of src/usr.bin/ssh/ssh-keygen.1, Revision 1.99
1.99 ! djm 1: .\" $OpenBSD: ssh-keygen.1,v 1.98 2010/08/04 06:07:11 djm 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.
32: .\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
33: .\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
34: .\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
35: .\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
36: .\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
37: .\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
38: .\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
1.1 deraadt 39: .\"
1.99 ! djm 40: .Dd $Mdocdate: August 4 2010 $
1.2 deraadt 41: .Dt SSH-KEYGEN 1
42: .Os
43: .Sh NAME
44: .Nm ssh-keygen
1.37 markus 45: .Nd authentication key generation, management and conversion
1.2 deraadt 46: .Sh SYNOPSIS
1.97 schwarze 47: .Bk -words
1.2 deraadt 48: .Nm ssh-keygen
1.25 markus 49: .Op Fl q
1.2 deraadt 50: .Op Fl b Ar bits
1.53 stevesk 51: .Fl t Ar type
1.2 deraadt 52: .Op Fl N Ar new_passphrase
53: .Op Fl C Ar comment
1.20 markus 54: .Op Fl f Ar output_keyfile
1.2 deraadt 55: .Nm ssh-keygen
56: .Fl p
57: .Op Fl P Ar old_passphrase
58: .Op Fl N Ar new_passphrase
1.9 markus 59: .Op Fl f Ar keyfile
1.2 deraadt 60: .Nm ssh-keygen
1.37 markus 61: .Fl i
1.95 djm 62: .Op Fl m Ar key_format
1.20 markus 63: .Op Fl f Ar input_keyfile
1.16 deraadt 64: .Nm ssh-keygen
1.37 markus 65: .Fl e
1.95 djm 66: .Op Fl m Ar key_format
1.20 markus 67: .Op Fl f Ar input_keyfile
1.16 deraadt 68: .Nm ssh-keygen
1.17 markus 69: .Fl y
1.20 markus 70: .Op Fl f Ar input_keyfile
1.17 markus 71: .Nm ssh-keygen
1.2 deraadt 72: .Fl c
73: .Op Fl P Ar passphrase
74: .Op Fl C Ar comment
1.9 markus 75: .Op Fl f Ar keyfile
76: .Nm ssh-keygen
77: .Fl l
1.35 markus 78: .Op Fl f Ar input_keyfile
79: .Nm ssh-keygen
80: .Fl B
1.20 markus 81: .Op Fl f Ar input_keyfile
1.48 jakob 82: .Nm ssh-keygen
1.82 jmc 83: .Fl D Ar pkcs11
1.48 jakob 84: .Nm ssh-keygen
1.64 djm 85: .Fl F Ar hostname
86: .Op Fl f Ar known_hosts_file
1.79 sthen 87: .Op Fl l
1.64 djm 88: .Nm ssh-keygen
89: .Fl H
90: .Op Fl f Ar known_hosts_file
91: .Nm ssh-keygen
92: .Fl R Ar hostname
93: .Op Fl f Ar known_hosts_file
1.57 jakob 94: .Nm ssh-keygen
95: .Fl r Ar hostname
96: .Op Fl f Ar input_keyfile
97: .Op Fl g
1.60 djm 98: .Nm ssh-keygen
99: .Fl G Ar output_file
1.61 djm 100: .Op Fl v
1.60 djm 101: .Op Fl b Ar bits
102: .Op Fl M Ar memory
103: .Op Fl S Ar start_point
104: .Nm ssh-keygen
105: .Fl T Ar output_file
106: .Fl f Ar input_file
1.61 djm 107: .Op Fl v
1.60 djm 108: .Op Fl a Ar num_trials
109: .Op Fl W Ar generator
1.84 djm 110: .Nm ssh-keygen
111: .Fl s Ar ca_key
112: .Fl I Ar certificate_identity
113: .Op Fl h
114: .Op Fl n Ar principals
1.93 djm 115: .Op Fl O Ar option
1.84 djm 116: .Op Fl V Ar validity_interval
1.93 djm 117: .Op Fl z Ar serial_number
1.84 djm 118: .Ar
1.86 djm 119: .Nm ssh-keygen
120: .Fl L
121: .Op Fl f Ar input_keyfile
1.85 jmc 122: .Ek
1.13 aaron 123: .Sh DESCRIPTION
1.2 deraadt 124: .Nm
1.37 markus 125: generates, manages and converts authentication keys for
1.2 deraadt 126: .Xr ssh 1 .
1.15 deraadt 127: .Nm
1.99 ! djm 128: can create RSA keys for use by SSH protocol version 1 and RSA, DSA or ECDSA
1.58 jmc 129: keys for use by SSH protocol version 2.
130: The type of key to be generated is specified with the
1.25 markus 131: .Fl t
1.52 djm 132: option.
1.70 djm 133: If invoked without any arguments,
134: .Nm
1.71 jmc 135: will generate an RSA key for use in SSH protocol 2 connections.
1.15 deraadt 136: .Pp
1.60 djm 137: .Nm
138: is also used to generate groups for use in Diffie-Hellman group
139: exchange (DH-GEX).
140: See the
141: .Sx MODULI GENERATION
142: section for details.
143: .Pp
1.2 deraadt 144: Normally each user wishing to use SSH
1.99 ! djm 145: with public key authentication runs this once to create the authentication
1.1 deraadt 146: key in
1.68 djm 147: .Pa ~/.ssh/identity ,
1.99 ! djm 148: .Pa ~/.ssh/id_ecdsa ,
1.68 djm 149: .Pa ~/.ssh/id_dsa
1.15 deraadt 150: or
1.68 djm 151: .Pa ~/.ssh/id_rsa .
1.15 deraadt 152: Additionally, the system administrator may use this to generate host keys,
153: as seen in
154: .Pa /etc/rc .
1.2 deraadt 155: .Pp
1.1 deraadt 156: Normally this program generates the key and asks for a file in which
1.12 aaron 157: to store the private key.
158: The public key is stored in a file with the same name but
1.2 deraadt 159: .Dq .pub
1.12 aaron 160: appended.
161: The program also asks for a passphrase.
162: The passphrase may be empty to indicate no passphrase
1.26 markus 163: (host keys must have an empty passphrase), or it may be a string of
1.12 aaron 164: arbitrary length.
1.51 stevesk 165: A passphrase is similar to a password, except it can be a phrase with a
166: series of words, punctuation, numbers, whitespace, or any string of
167: characters you want.
168: Good passphrases are 10-30 characters long, are
1.1 deraadt 169: not simple sentences or otherwise easily guessable (English
1.42 markus 170: prose has only 1-2 bits of entropy per character, and provides very bad
1.51 stevesk 171: passphrases), and contain a mix of upper and lowercase letters,
172: numbers, and non-alphanumeric characters.
1.12 aaron 173: The passphrase can be changed later by using the
1.2 deraadt 174: .Fl p
1.1 deraadt 175: option.
1.2 deraadt 176: .Pp
1.12 aaron 177: There is no way to recover a lost passphrase.
178: If the passphrase is
1.49 deraadt 179: lost or forgotten, a new key must be generated and copied to the
1.1 deraadt 180: corresponding public key to other machines.
1.2 deraadt 181: .Pp
1.37 markus 182: For RSA1 keys,
183: there is also a comment field in the key file that is only for
1.12 aaron 184: convenience to the user to help identify the key.
185: The comment can tell what the key is for, or whatever is useful.
186: The comment is initialized to
1.2 deraadt 187: .Dq user@host
188: when the key is created, but can be changed using the
189: .Fl c
1.1 deraadt 190: option.
1.2 deraadt 191: .Pp
1.15 deraadt 192: After a key is generated, instructions below detail where the keys
193: should be placed to be activated.
194: .Pp
1.2 deraadt 195: The options are as follows:
196: .Bl -tag -width Ds
1.60 djm 197: .It Fl a Ar trials
198: Specifies the number of primality tests to perform when screening DH-GEX
199: candidates using the
200: .Fl T
201: command.
1.66 jmc 202: .It Fl B
203: Show the bubblebabble digest of specified private or public key file.
1.2 deraadt 204: .It Fl b Ar bits
1.12 aaron 205: Specifies the number of bits in the key to create.
1.72 dtucker 206: For RSA keys, the minimum size is 768 bits and the default is 2048 bits.
1.69 djm 207: Generally, 2048 bits is considered sufficient.
1.72 dtucker 208: DSA keys must be exactly 1024 bits as specified by FIPS 186-2.
1.66 jmc 209: .It Fl C Ar comment
210: Provides a new comment.
1.2 deraadt 211: .It Fl c
1.1 deraadt 212: Requests changing the comment in the private and public key files.
1.50 markus 213: This operation is only supported for RSA1 keys.
1.1 deraadt 214: The program will prompt for the file containing the private keys, for
1.41 stevesk 215: the passphrase if the key has one, and for the new comment.
1.81 markus 216: .It Fl D Ar pkcs11
1.83 markus 217: Download the RSA public keys provided by the PKCS#11 shared library
218: .Ar pkcs11 .
1.98 djm 219: When used in combination with
220: .Fl s ,
221: this option indicates that a CA key resides in a PKCS#11 token (see the
222: .Sx CERTIFICATES
223: section for details).
1.37 markus 224: .It Fl e
1.40 markus 225: This option will read a private or public OpenSSH key file and
1.95 djm 226: print to stdout the key in one of the formats specified by the
227: .Fl m
228: option.
229: The default export format is
230: .Dq RFC4716 .
1.96 jmc 231: This option allows exporting OpenSSH keys for use by other programs, including
1.95 djm 232: several commercial SSH implementations.
1.66 jmc 233: .It Fl F Ar hostname
234: Search for the specified
235: .Ar hostname
236: in a
237: .Pa known_hosts
238: file, listing any occurrences found.
239: This option is useful to find hashed host names or addresses and may also be
240: used in conjunction with the
241: .Fl H
242: option to print found keys in a hashed format.
243: .It Fl f Ar filename
244: Specifies the filename of the key file.
245: .It Fl G Ar output_file
246: Generate candidate primes for DH-GEX.
247: These primes must be screened for
248: safety (using the
249: .Fl T
250: option) before use.
1.57 jakob 251: .It Fl g
1.62 jakob 252: Use generic DNS format when printing fingerprint resource records using the
1.63 jmc 253: .Fl r
1.62 jakob 254: command.
1.66 jmc 255: .It Fl H
256: Hash a
257: .Pa known_hosts
1.67 dtucker 258: file.
259: This replaces all hostnames and addresses with hashed representations
260: within the specified file; the original content is moved to a file with
261: a .old suffix.
1.66 jmc 262: These hashes may be used normally by
263: .Nm ssh
264: and
265: .Nm sshd ,
266: but they do not reveal identifying information should the file's contents
267: be disclosed.
268: This option will not modify existing hashed hostnames and is therefore safe
269: to use on files that mix hashed and non-hashed names.
1.84 djm 270: .It Fl h
271: When signing a key, create a host certificate instead of a user
272: certificate.
273: Please see the
274: .Sx CERTIFICATES
275: section for details.
1.85 jmc 276: .It Fl I Ar certificate_identity
1.84 djm 277: Specify the key identity when signing a public key.
278: Please see the
279: .Sx CERTIFICATES
280: section for details.
1.37 markus 281: .It Fl i
282: This option will read an unencrypted private (or public) key file
1.95 djm 283: in the format specified by the
284: .Fl m
285: option and print an OpenSSH compatible private
1.37 markus 286: (or public) key to stdout.
1.95 djm 287: This option allows importing keys from other software, including several
288: commercial SSH implementations.
289: The default import format is
290: .Dq RFC4716 .
1.86 djm 291: .It Fl L
292: Prints the contents of a certificate.
1.9 markus 293: .It Fl l
1.77 grunk 294: Show fingerprint of specified public key file.
1.50 markus 295: Private RSA1 keys are also supported.
296: For RSA and DSA keys
297: .Nm
1.78 jmc 298: tries to find the matching public key file and prints its fingerprint.
299: If combined with
300: .Fl v ,
301: an ASCII art representation of the key is supplied with the fingerprint.
1.96 jmc 302: .It Fl M Ar memory
303: Specify the amount of memory to use (in megabytes) when generating
304: candidate moduli for DH-GEX.
1.95 djm 305: .It Fl m Ar key_format
306: Specify a key format for the
307: .Fl i
308: (import) or
309: .Fl e
1.96 jmc 310: (export) conversion options.
1.95 djm 311: The supported key formats are:
312: .Dq RFC4716
1.96 jmc 313: (RFC 4716/SSH2 public or private key),
1.95 djm 314: .Dq PKCS8
315: (PEM PKCS8 public key)
316: or
317: .Dq PEM
318: (PEM public key).
319: The default conversion format is
320: .Dq RFC4716 .
1.66 jmc 321: .It Fl N Ar new_passphrase
322: Provides the new passphrase.
1.84 djm 323: .It Fl n Ar principals
324: Specify one or more principals (user or host names) to be included in
325: a certificate when signing a key.
326: Multiple principals may be specified, separated by commas.
327: Please see the
328: .Sx CERTIFICATES
329: section for details.
1.93 djm 330: .It Fl O Ar option
331: Specify a certificate option when signing a key.
1.84 djm 332: This option may be specified multiple times.
333: Please see the
334: .Sx CERTIFICATES
335: section for details.
1.93 djm 336: The options that are valid for user certificates are:
1.84 djm 337: .Bl -tag -width Ds
1.89 jmc 338: .It Ic clear
339: Clear all enabled permissions.
340: This is useful for clearing the default set of permissions so permissions may
341: be added individually.
342: .It Ic force-command Ns = Ns Ar command
343: Forces the execution of
344: .Ar command
345: instead of any shell or command specified by the user when
346: the certificate is used for authentication.
1.84 djm 347: .It Ic no-agent-forwarding
348: Disable
349: .Xr ssh-agent 1
1.85 jmc 350: forwarding (permitted by default).
1.84 djm 351: .It Ic no-port-forwarding
1.85 jmc 352: Disable port forwarding (permitted by default).
1.84 djm 353: .It Ic no-pty
1.85 jmc 354: Disable PTY allocation (permitted by default).
1.84 djm 355: .It Ic no-user-rc
356: Disable execution of
357: .Pa ~/.ssh/rc
358: by
1.85 jmc 359: .Xr sshd 8
360: (permitted by default).
1.89 jmc 361: .It Ic no-x11-forwarding
362: Disable X11 forwarding (permitted by default).
1.88 djm 363: .It Ic permit-agent-forwarding
364: Allows
365: .Xr ssh-agent 1
366: forwarding.
1.84 djm 367: .It Ic permit-port-forwarding
368: Allows port forwarding.
369: .It Ic permit-pty
370: Allows PTY allocation.
371: .It Ic permit-user-rc
372: Allows execution of
373: .Pa ~/.ssh/rc
374: by
375: .Xr sshd 8 .
1.89 jmc 376: .It Ic permit-x11-forwarding
377: Allows X11 forwarding.
378: .It Ic source-address Ns = Ns Ar address_list
1.90 jmc 379: Restrict the source addresses from which the certificate is considered valid.
1.84 djm 380: The
381: .Ar address_list
382: is a comma-separated list of one or more address/netmask pairs in CIDR
383: format.
384: .El
385: .Pp
1.93 djm 386: At present, no options are valid for host keys.
1.66 jmc 387: .It Fl P Ar passphrase
388: Provides the (old) passphrase.
1.2 deraadt 389: .It Fl p
1.1 deraadt 390: Requests changing the passphrase of a private key file instead of
1.12 aaron 391: creating a new private key.
392: The program will prompt for the file
1.1 deraadt 393: containing the private key, for the old passphrase, and twice for the
394: new passphrase.
1.5 aaron 395: .It Fl q
396: Silence
397: .Nm ssh-keygen .
398: Used by
399: .Pa /etc/rc
400: when creating a new key.
1.64 djm 401: .It Fl R Ar hostname
402: Removes all keys belonging to
403: .Ar hostname
1.65 jmc 404: from a
1.64 djm 405: .Pa known_hosts
406: file.
1.65 jmc 407: This option is useful to delete hashed hosts (see the
1.64 djm 408: .Fl H
409: option above).
1.66 jmc 410: .It Fl r Ar hostname
411: Print the SSHFP fingerprint resource record named
412: .Ar hostname
413: for the specified public key file.
1.60 djm 414: .It Fl S Ar start
415: Specify start point (in hex) when generating candidate moduli for DH-GEX.
1.84 djm 416: .It Fl s Ar ca_key
417: Certify (sign) a public key using the specified CA key.
418: Please see the
419: .Sx CERTIFICATES
420: section for details.
1.60 djm 421: .It Fl T Ar output_file
422: Test DH group exchange candidate primes (generated using the
423: .Fl G
424: option) for safety.
1.66 jmc 425: .It Fl t Ar type
426: Specifies the type of key to create.
427: The possible values are
428: .Dq rsa1
429: for protocol version 1 and
430: .Dq rsa
431: or
432: .Dq dsa
433: for protocol version 2.
1.84 djm 434: .It Fl V Ar validity_interval
435: Specify a validity interval when signing a certificate.
436: A validity interval may consist of a single time, indicating that the
437: certificate is valid beginning now and expiring at that time, or may consist
438: of two times separated by a colon to indicate an explicit time interval.
439: The start time may be specified as a date in YYYYMMDD format, a time
440: in YYYYMMDDHHMMSS format or a relative time (to the current time) consisting
441: of a minus sign followed by a relative time in the format described in the
442: .Sx TIME FORMATS
443: section of
1.90 jmc 444: .Xr sshd_config 5 .
1.84 djm 445: The end time may be specified as a YYYYMMDD date, a YYYYMMDDHHMMSS time or
446: a relative time starting with a plus character.
447: .Pp
448: For example:
449: .Dq +52w1d
450: (valid from now to 52 weeks and one day from now),
451: .Dq -4w:+4w
452: (valid from four weeks ago to four weeks from now),
453: .Dq 20100101123000:20110101123000
454: (valid from 12:30 PM, January 1st, 2010 to 12:30 PM, January 1st, 2011),
455: .Dq -1d:20110101
456: (valid from yesterday to midnight, January 1st, 2011).
1.61 djm 457: .It Fl v
458: Verbose mode.
459: Causes
460: .Nm
461: to print debugging messages about its progress.
462: This is helpful for debugging moduli generation.
463: Multiple
464: .Fl v
465: options increase the verbosity.
466: The maximum is 3.
1.66 jmc 467: .It Fl W Ar generator
468: Specify desired generator when testing candidate moduli for DH-GEX.
469: .It Fl y
470: This option will read a private
471: OpenSSH format file and print an OpenSSH public key to stdout.
1.93 djm 472: .It Fl z Ar serial_number
473: Specifies a serial number to be embedded in the certificate to distinguish
474: this certificate from others from the same CA.
475: The default serial number is zero.
1.2 deraadt 476: .El
1.60 djm 477: .Sh MODULI GENERATION
478: .Nm
479: may be used to generate groups for the Diffie-Hellman Group Exchange
480: (DH-GEX) protocol.
481: Generating these groups is a two-step process: first, candidate
482: primes are generated using a fast, but memory intensive process.
483: These candidate primes are then tested for suitability (a CPU-intensive
484: process).
485: .Pp
486: Generation of primes is performed using the
487: .Fl G
488: option.
489: The desired length of the primes may be specified by the
490: .Fl b
491: option.
492: For example:
493: .Pp
1.66 jmc 494: .Dl # ssh-keygen -G moduli-2048.candidates -b 2048
1.60 djm 495: .Pp
496: By default, the search for primes begins at a random point in the
497: desired length range.
498: This may be overridden using the
499: .Fl S
500: option, which specifies a different start point (in hex).
501: .Pp
502: Once a set of candidates have been generated, they must be tested for
503: suitability.
504: This may be performed using the
505: .Fl T
506: option.
507: In this mode
508: .Nm
509: will read candidates from standard input (or a file specified using the
510: .Fl f
511: option).
512: For example:
513: .Pp
1.66 jmc 514: .Dl # ssh-keygen -T moduli-2048 -f moduli-2048.candidates
1.60 djm 515: .Pp
516: By default, each candidate will be subjected to 100 primality tests.
517: This may be overridden using the
518: .Fl a
519: option.
520: The DH generator value will be chosen automatically for the
521: prime under consideration.
522: If a specific generator is desired, it may be requested using the
523: .Fl W
524: option.
1.66 jmc 525: Valid generator values are 2, 3, and 5.
1.60 djm 526: .Pp
527: Screened DH groups may be installed in
528: .Pa /etc/moduli .
529: It is important that this file contains moduli of a range of bit lengths and
530: that both ends of a connection share common moduli.
1.84 djm 531: .Sh CERTIFICATES
532: .Nm
533: supports signing of keys to produce certificates that may be used for
534: user or host authentication.
535: Certificates consist of a public key, some identity information, zero or
1.94 jmc 536: more principal (user or host) names and a set of options that
1.84 djm 537: are signed by a Certification Authority (CA) key.
538: Clients or servers may then trust only the CA key and verify its signature
539: on a certificate rather than trusting many user/host keys.
540: Note that OpenSSH certificates are a different, and much simpler, format to
541: the X.509 certificates used in
542: .Xr ssl 8 .
543: .Pp
544: .Nm
545: supports two types of certificates: user and host.
546: User certificates authenticate users to servers, whereas host certificates
1.85 jmc 547: authenticate server hosts to users.
548: To generate a user certificate:
1.84 djm 549: .Pp
550: .Dl $ ssh-keygen -s /path/to/ca_key -I key_id /path/to/user_key.pub
551: .Pp
552: The resultant certificate will be placed in
1.91 djm 553: .Pa /path/to/user_key-cert.pub .
1.84 djm 554: A host certificate requires the
555: .Fl h
556: option:
557: .Pp
558: .Dl $ ssh-keygen -s /path/to/ca_key -I key_id -h /path/to/host_key.pub
559: .Pp
560: The host certificate will be output to
1.91 djm 561: .Pa /path/to/host_key-cert.pub .
1.98 djm 562: .Pp
563: It is possible to sign using a CA key stored in a PKCS#11 token by
564: providing the token library using
565: .Fl D
566: and identifying the CA key by providing its public half as an argument
567: to
568: .Fl s :
569: .Pp
570: .Dl $ ssh-keygen -s ca_key.pub -D libpkcs11.so -I key_id host_key.pub
571: .Pp
572: In all cases,
1.84 djm 573: .Ar key_id
574: is a "key identifier" that is logged by the server when the certificate
575: is used for authentication.
576: .Pp
577: Certificates may be limited to be valid for a set of principal (user/host)
578: names.
579: By default, generated certificates are valid for all users or hosts.
580: To generate a certificate for a specified set of principals:
581: .Pp
582: .Dl $ ssh-keygen -s ca_key -I key_id -n user1,user2 user_key.pub
1.92 jmc 583: .Dl "$ ssh-keygen -s ca_key -I key_id -h -n host.domain user_key.pub"
1.84 djm 584: .Pp
585: Additional limitations on the validity and use of user certificates may
1.94 jmc 586: be specified through certificate options.
1.93 djm 587: A certificate option may disable features of the SSH session, may be
1.84 djm 588: valid only when presented from particular source addresses or may
589: force the use of a specific command.
1.93 djm 590: For a list of valid certificate options, see the documentation for the
1.84 djm 591: .Fl O
592: option above.
593: .Pp
594: Finally, certificates may be defined with a validity lifetime.
595: The
596: .Fl V
597: option allows specification of certificate start and end times.
598: A certificate that is presented at a time outside this range will not be
599: considered valid.
600: By default, certificates have a maximum validity interval.
601: .Pp
602: For certificates to be used for user or host authentication, the CA
603: public key must be trusted by
604: .Xr sshd 8
605: or
606: .Xr ssh 1 .
607: Please refer to those manual pages for details.
1.2 deraadt 608: .Sh FILES
609: .Bl -tag -width Ds
1.68 djm 610: .It Pa ~/.ssh/identity
1.36 itojun 611: Contains the protocol version 1 RSA authentication identity of the user.
1.12 aaron 612: This file should not be readable by anyone but the user.
613: It is possible to
1.1 deraadt 614: specify a passphrase when generating the key; that passphrase will be
1.80 dtucker 615: used to encrypt the private part of this file using 128-bit AES.
1.12 aaron 616: This file is not automatically accessed by
1.2 deraadt 617: .Nm
1.1 deraadt 618: but it is offered as the default file for the private key.
1.46 markus 619: .Xr ssh 1
1.15 deraadt 620: will read this file when a login attempt is made.
1.68 djm 621: .It Pa ~/.ssh/identity.pub
1.36 itojun 622: Contains the protocol version 1 RSA public key for authentication.
1.12 aaron 623: The contents of this file should be added to
1.68 djm 624: .Pa ~/.ssh/authorized_keys
1.2 deraadt 625: on all machines
1.49 deraadt 626: where the user wishes to log in using RSA authentication.
1.15 deraadt 627: There is no need to keep the contents of this file secret.
1.68 djm 628: .It Pa ~/.ssh/id_dsa
1.36 itojun 629: Contains the protocol version 2 DSA authentication identity of the user.
1.15 deraadt 630: This file should not be readable by anyone but the user.
631: It is possible to
632: specify a passphrase when generating the key; that passphrase will be
1.80 dtucker 633: used to encrypt the private part of this file using 128-bit AES.
1.15 deraadt 634: This file is not automatically accessed by
635: .Nm
636: but it is offered as the default file for the private key.
1.46 markus 637: .Xr ssh 1
1.15 deraadt 638: will read this file when a login attempt is made.
1.68 djm 639: .It Pa ~/.ssh/id_dsa.pub
1.36 itojun 640: Contains the protocol version 2 DSA public key for authentication.
641: The contents of this file should be added to
1.68 djm 642: .Pa ~/.ssh/authorized_keys
1.36 itojun 643: on all machines
1.49 deraadt 644: where the user wishes to log in using public key authentication.
1.36 itojun 645: There is no need to keep the contents of this file secret.
1.68 djm 646: .It Pa ~/.ssh/id_rsa
1.36 itojun 647: Contains the protocol version 2 RSA authentication identity of the user.
648: This file should not be readable by anyone but the user.
649: It is possible to
650: specify a passphrase when generating the key; that passphrase will be
1.80 dtucker 651: used to encrypt the private part of this file using 128-bit AES.
1.36 itojun 652: This file is not automatically accessed by
653: .Nm
654: but it is offered as the default file for the private key.
1.46 markus 655: .Xr ssh 1
1.36 itojun 656: will read this file when a login attempt is made.
1.68 djm 657: .It Pa ~/.ssh/id_rsa.pub
1.36 itojun 658: Contains the protocol version 2 RSA public key for authentication.
1.15 deraadt 659: The contents of this file should be added to
1.68 djm 660: .Pa ~/.ssh/authorized_keys
1.15 deraadt 661: on all machines
1.49 deraadt 662: where the user wishes to log in using public key authentication.
1.12 aaron 663: There is no need to keep the contents of this file secret.
1.60 djm 664: .It Pa /etc/moduli
665: Contains Diffie-Hellman groups used for DH-GEX.
666: The file format is described in
667: .Xr moduli 5 .
1.19 aaron 668: .El
1.2 deraadt 669: .Sh SEE ALSO
670: .Xr ssh 1 ,
671: .Xr ssh-add 1 ,
1.8 ericj 672: .Xr ssh-agent 1 ,
1.60 djm 673: .Xr moduli 5 ,
1.30 itojun 674: .Xr sshd 8
1.37 markus 675: .Rs
1.73 markus 676: .%R RFC 4716
677: .%T "The Secure Shell (SSH) Public Key File Format"
678: .%D 2006
1.37 markus 679: .Re
1.59 jmc 680: .Sh AUTHORS
681: OpenSSH is a derivative of the original and free
682: ssh 1.2.12 release by Tatu Ylonen.
683: Aaron Campbell, Bob Beck, Markus Friedl, Niels Provos,
684: Theo de Raadt and Dug Song
685: removed many bugs, re-added newer features and
686: created OpenSSH.
687: Markus Friedl contributed the support for SSH
688: protocol versions 1.5 and 2.0.