Annotation of src/usr.bin/ssh/ssh-keygen.1, Revision 1.108
1.108 ! dtucker 1: .\" $OpenBSD: ssh-keygen.1,v 1.107 2011/09/07 02:18:31 deraadt Exp $
1.1 deraadt 2: .\"
3: .\" Author: Tatu Ylonen <ylo@cs.hut.fi>
4: .\" Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland
5: .\" All rights reserved
6: .\"
1.22 deraadt 7: .\" As far as I am concerned, the code I have written for this software
8: .\" can be used freely for any purpose. Any derived versions of this
9: .\" software must be clearly marked as such, and if the derived work is
10: .\" incompatible with the protocol description in the RFC file, it must be
11: .\" called by a name other than "ssh" or "Secure Shell".
12: .\"
13: .\"
1.33 deraadt 14: .\" Copyright (c) 1999,2000 Markus Friedl. All rights reserved.
15: .\" Copyright (c) 1999 Aaron Campbell. All rights reserved.
16: .\" Copyright (c) 1999 Theo de Raadt. All rights reserved.
1.22 deraadt 17: .\"
18: .\" Redistribution and use in source and binary forms, with or without
19: .\" modification, are permitted provided that the following conditions
20: .\" are met:
21: .\" 1. Redistributions of source code must retain the above copyright
22: .\" notice, this list of conditions and the following disclaimer.
23: .\" 2. Redistributions in binary form must reproduce the above copyright
24: .\" notice, this list of conditions and the following disclaimer in the
25: .\" documentation and/or other materials provided with the distribution.
1.1 deraadt 26: .\"
1.22 deraadt 27: .\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
28: .\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
29: .\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
30: .\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
31: .\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
32: .\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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36: .\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
1.1 deraadt 37: .\"
1.108 ! dtucker 38: .Dd $Mdocdate: September 7 2011 $
1.2 deraadt 39: .Dt SSH-KEYGEN 1
40: .Os
41: .Sh NAME
42: .Nm ssh-keygen
1.37 markus 43: .Nd authentication key generation, management and conversion
1.2 deraadt 44: .Sh SYNOPSIS
1.97 schwarze 45: .Bk -words
1.2 deraadt 46: .Nm ssh-keygen
1.25 markus 47: .Op Fl q
1.2 deraadt 48: .Op Fl b Ar bits
1.53 stevesk 49: .Fl t Ar type
1.2 deraadt 50: .Op Fl N Ar new_passphrase
51: .Op Fl C Ar comment
1.20 markus 52: .Op Fl f Ar output_keyfile
1.2 deraadt 53: .Nm ssh-keygen
54: .Fl p
55: .Op Fl P Ar old_passphrase
56: .Op Fl N Ar new_passphrase
1.9 markus 57: .Op Fl f Ar keyfile
1.2 deraadt 58: .Nm ssh-keygen
1.37 markus 59: .Fl i
1.95 djm 60: .Op Fl m Ar key_format
1.20 markus 61: .Op Fl f Ar input_keyfile
1.16 deraadt 62: .Nm ssh-keygen
1.37 markus 63: .Fl e
1.95 djm 64: .Op Fl m Ar key_format
1.20 markus 65: .Op Fl f Ar input_keyfile
1.16 deraadt 66: .Nm ssh-keygen
1.17 markus 67: .Fl y
1.20 markus 68: .Op Fl f Ar input_keyfile
1.17 markus 69: .Nm ssh-keygen
1.2 deraadt 70: .Fl c
71: .Op Fl P Ar passphrase
72: .Op Fl C Ar comment
1.9 markus 73: .Op Fl f Ar keyfile
74: .Nm ssh-keygen
75: .Fl l
1.35 markus 76: .Op Fl f Ar input_keyfile
77: .Nm ssh-keygen
78: .Fl B
1.20 markus 79: .Op Fl f Ar input_keyfile
1.48 jakob 80: .Nm ssh-keygen
1.82 jmc 81: .Fl D Ar pkcs11
1.48 jakob 82: .Nm ssh-keygen
1.64 djm 83: .Fl F Ar hostname
84: .Op Fl f Ar known_hosts_file
1.79 sthen 85: .Op Fl l
1.64 djm 86: .Nm ssh-keygen
87: .Fl H
88: .Op Fl f Ar known_hosts_file
89: .Nm ssh-keygen
90: .Fl R Ar hostname
91: .Op Fl f Ar known_hosts_file
1.57 jakob 92: .Nm ssh-keygen
93: .Fl r Ar hostname
94: .Op Fl f Ar input_keyfile
95: .Op Fl g
1.60 djm 96: .Nm ssh-keygen
97: .Fl G Ar output_file
1.61 djm 98: .Op Fl v
1.60 djm 99: .Op Fl b Ar bits
100: .Op Fl M Ar memory
101: .Op Fl S Ar start_point
102: .Nm ssh-keygen
103: .Fl T Ar output_file
104: .Fl f Ar input_file
1.61 djm 105: .Op Fl v
1.60 djm 106: .Op Fl a Ar num_trials
1.108 ! dtucker 107: .Op Fl K Ar checkpt
1.60 djm 108: .Op Fl W Ar generator
1.84 djm 109: .Nm ssh-keygen
110: .Fl s Ar ca_key
111: .Fl I Ar certificate_identity
112: .Op Fl h
113: .Op Fl n Ar principals
1.93 djm 114: .Op Fl O Ar option
1.84 djm 115: .Op Fl V Ar validity_interval
1.93 djm 116: .Op Fl z Ar serial_number
1.84 djm 117: .Ar
1.86 djm 118: .Nm ssh-keygen
119: .Fl L
120: .Op Fl f Ar input_keyfile
1.102 stevesk 121: .Nm ssh-keygen
122: .Fl A
1.85 jmc 123: .Ek
1.13 aaron 124: .Sh DESCRIPTION
1.2 deraadt 125: .Nm
1.37 markus 126: generates, manages and converts authentication keys for
1.2 deraadt 127: .Xr ssh 1 .
1.15 deraadt 128: .Nm
1.100 naddy 129: can create RSA keys for use by SSH protocol version 1 and DSA, ECDSA or RSA
1.58 jmc 130: keys for use by SSH protocol version 2.
131: The type of key to be generated is specified with the
1.25 markus 132: .Fl t
1.52 djm 133: option.
1.70 djm 134: If invoked without any arguments,
135: .Nm
1.71 jmc 136: will generate an RSA key for use in SSH protocol 2 connections.
1.15 deraadt 137: .Pp
1.60 djm 138: .Nm
139: is also used to generate groups for use in Diffie-Hellman group
140: exchange (DH-GEX).
141: See the
142: .Sx MODULI GENERATION
143: section for details.
144: .Pp
1.2 deraadt 145: Normally each user wishing to use SSH
1.99 djm 146: with public key authentication runs this once to create the authentication
1.1 deraadt 147: key in
1.68 djm 148: .Pa ~/.ssh/identity ,
1.99 djm 149: .Pa ~/.ssh/id_ecdsa ,
1.68 djm 150: .Pa ~/.ssh/id_dsa
1.15 deraadt 151: or
1.68 djm 152: .Pa ~/.ssh/id_rsa .
1.15 deraadt 153: Additionally, the system administrator may use this to generate host keys,
154: as seen in
155: .Pa /etc/rc .
1.2 deraadt 156: .Pp
1.1 deraadt 157: Normally this program generates the key and asks for a file in which
1.12 aaron 158: to store the private key.
159: The public key is stored in a file with the same name but
1.2 deraadt 160: .Dq .pub
1.12 aaron 161: appended.
162: The program also asks for a passphrase.
163: The passphrase may be empty to indicate no passphrase
1.26 markus 164: (host keys must have an empty passphrase), or it may be a string of
1.12 aaron 165: arbitrary length.
1.51 stevesk 166: A passphrase is similar to a password, except it can be a phrase with a
167: series of words, punctuation, numbers, whitespace, or any string of
168: characters you want.
169: Good passphrases are 10-30 characters long, are
1.1 deraadt 170: not simple sentences or otherwise easily guessable (English
1.42 markus 171: prose has only 1-2 bits of entropy per character, and provides very bad
1.51 stevesk 172: passphrases), and contain a mix of upper and lowercase letters,
173: numbers, and non-alphanumeric characters.
1.12 aaron 174: The passphrase can be changed later by using the
1.2 deraadt 175: .Fl p
1.1 deraadt 176: option.
1.2 deraadt 177: .Pp
1.12 aaron 178: There is no way to recover a lost passphrase.
1.105 djm 179: If the passphrase is lost or forgotten, a new key must be generated
180: and the corresponding public key copied 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
1.102 stevesk 197: .It Fl A
198: For each of the key types (rsa1, rsa, dsa and ecdsa) for which host keys
199: do not exist, generate the host keys with the default key file path,
200: an empty passphrase, default bits for the key type, and default comment.
1.104 jmc 201: This is used by
1.102 stevesk 202: .Pa /etc/rc
203: to generate new host keys.
1.60 djm 204: .It Fl a Ar trials
205: Specifies the number of primality tests to perform when screening DH-GEX
206: candidates using the
207: .Fl T
208: command.
1.66 jmc 209: .It Fl B
210: Show the bubblebabble digest of specified private or public key file.
1.2 deraadt 211: .It Fl b Ar bits
1.12 aaron 212: Specifies the number of bits in the key to create.
1.72 dtucker 213: For RSA keys, the minimum size is 768 bits and the default is 2048 bits.
1.69 djm 214: Generally, 2048 bits is considered sufficient.
1.72 dtucker 215: DSA keys must be exactly 1024 bits as specified by FIPS 186-2.
1.106 djm 216: For ECDSA keys, the
217: .Fl b
1.107 deraadt 218: flag determines the key length by selecting from one of three elliptic
1.106 djm 219: curve sizes: 256, 384 or 521 bits.
220: Attempting to use bit lengths other than these three values for ECDSA keys
221: will fail.
1.66 jmc 222: .It Fl C Ar comment
223: Provides a new comment.
1.2 deraadt 224: .It Fl c
1.1 deraadt 225: Requests changing the comment in the private and public key files.
1.50 markus 226: This operation is only supported for RSA1 keys.
1.1 deraadt 227: The program will prompt for the file containing the private keys, for
1.41 stevesk 228: the passphrase if the key has one, and for the new comment.
1.81 markus 229: .It Fl D Ar pkcs11
1.83 markus 230: Download the RSA public keys provided by the PKCS#11 shared library
231: .Ar pkcs11 .
1.98 djm 232: When used in combination with
233: .Fl s ,
234: this option indicates that a CA key resides in a PKCS#11 token (see the
235: .Sx CERTIFICATES
236: section for details).
1.37 markus 237: .It Fl e
1.40 markus 238: This option will read a private or public OpenSSH key file and
1.95 djm 239: print to stdout the key in one of the formats specified by the
240: .Fl m
241: option.
242: The default export format is
243: .Dq RFC4716 .
1.96 jmc 244: This option allows exporting OpenSSH keys for use by other programs, including
1.95 djm 245: several commercial SSH implementations.
1.66 jmc 246: .It Fl F Ar hostname
247: Search for the specified
248: .Ar hostname
249: in a
250: .Pa known_hosts
251: file, listing any occurrences found.
252: This option is useful to find hashed host names or addresses and may also be
253: used in conjunction with the
254: .Fl H
255: option to print found keys in a hashed format.
256: .It Fl f Ar filename
257: Specifies the filename of the key file.
258: .It Fl G Ar output_file
259: Generate candidate primes for DH-GEX.
260: These primes must be screened for
261: safety (using the
262: .Fl T
263: option) before use.
1.57 jakob 264: .It Fl g
1.62 jakob 265: Use generic DNS format when printing fingerprint resource records using the
1.63 jmc 266: .Fl r
1.62 jakob 267: command.
1.66 jmc 268: .It Fl H
269: Hash a
270: .Pa known_hosts
1.67 dtucker 271: file.
272: This replaces all hostnames and addresses with hashed representations
273: within the specified file; the original content is moved to a file with
274: a .old suffix.
1.66 jmc 275: These hashes may be used normally by
276: .Nm ssh
277: and
278: .Nm sshd ,
279: but they do not reveal identifying information should the file's contents
280: be disclosed.
281: This option will not modify existing hashed hostnames and is therefore safe
282: to use on files that mix hashed and non-hashed names.
1.84 djm 283: .It Fl h
284: When signing a key, create a host certificate instead of a user
285: certificate.
286: Please see the
287: .Sx CERTIFICATES
288: section for details.
1.85 jmc 289: .It Fl I Ar certificate_identity
1.84 djm 290: Specify the key identity when signing a public key.
291: Please see the
292: .Sx CERTIFICATES
293: section for details.
1.37 markus 294: .It Fl i
295: This option will read an unencrypted private (or public) key file
1.95 djm 296: in the format specified by the
297: .Fl m
298: option and print an OpenSSH compatible private
1.37 markus 299: (or public) key to stdout.
1.108 ! dtucker 300: .It Fl K Ar checkpt
! 301: Write the last line processed to the file
! 302: .Ar checkpt
! 303: while performing DH candidate screening using the
! 304: .Fl T
! 305: option.
! 306: This will be used to skip lines in the input file that have already been
! 307: processed if the job is restarted.
1.95 djm 308: This option allows importing keys from other software, including several
309: commercial SSH implementations.
310: The default import format is
311: .Dq RFC4716 .
1.86 djm 312: .It Fl L
313: Prints the contents of a certificate.
1.9 markus 314: .It Fl l
1.77 grunk 315: Show fingerprint of specified public key file.
1.50 markus 316: Private RSA1 keys are also supported.
317: For RSA and DSA keys
318: .Nm
1.78 jmc 319: tries to find the matching public key file and prints its fingerprint.
320: If combined with
321: .Fl v ,
322: an ASCII art representation of the key is supplied with the fingerprint.
1.96 jmc 323: .It Fl M Ar memory
324: Specify the amount of memory to use (in megabytes) when generating
325: candidate moduli for DH-GEX.
1.95 djm 326: .It Fl m Ar key_format
327: Specify a key format for the
328: .Fl i
329: (import) or
330: .Fl e
1.96 jmc 331: (export) conversion options.
1.95 djm 332: The supported key formats are:
333: .Dq RFC4716
1.96 jmc 334: (RFC 4716/SSH2 public or private key),
1.95 djm 335: .Dq PKCS8
336: (PEM PKCS8 public key)
337: or
338: .Dq PEM
339: (PEM public key).
340: The default conversion format is
341: .Dq RFC4716 .
1.66 jmc 342: .It Fl N Ar new_passphrase
343: Provides the new passphrase.
1.84 djm 344: .It Fl n Ar principals
345: Specify one or more principals (user or host names) to be included in
346: a certificate when signing a key.
347: Multiple principals may be specified, separated by commas.
348: Please see the
349: .Sx CERTIFICATES
350: section for details.
1.93 djm 351: .It Fl O Ar option
352: Specify a certificate option when signing a key.
1.84 djm 353: This option may be specified multiple times.
354: Please see the
355: .Sx CERTIFICATES
356: section for details.
1.93 djm 357: The options that are valid for user certificates are:
1.84 djm 358: .Bl -tag -width Ds
1.89 jmc 359: .It Ic clear
360: Clear all enabled permissions.
361: This is useful for clearing the default set of permissions so permissions may
362: be added individually.
363: .It Ic force-command Ns = Ns Ar command
364: Forces the execution of
365: .Ar command
366: instead of any shell or command specified by the user when
367: the certificate is used for authentication.
1.84 djm 368: .It Ic no-agent-forwarding
369: Disable
370: .Xr ssh-agent 1
1.85 jmc 371: forwarding (permitted by default).
1.84 djm 372: .It Ic no-port-forwarding
1.85 jmc 373: Disable port forwarding (permitted by default).
1.84 djm 374: .It Ic no-pty
1.85 jmc 375: Disable PTY allocation (permitted by default).
1.84 djm 376: .It Ic no-user-rc
377: Disable execution of
378: .Pa ~/.ssh/rc
379: by
1.85 jmc 380: .Xr sshd 8
381: (permitted by default).
1.89 jmc 382: .It Ic no-x11-forwarding
383: Disable X11 forwarding (permitted by default).
1.88 djm 384: .It Ic permit-agent-forwarding
385: Allows
386: .Xr ssh-agent 1
387: forwarding.
1.84 djm 388: .It Ic permit-port-forwarding
389: Allows port forwarding.
390: .It Ic permit-pty
391: Allows PTY allocation.
392: .It Ic permit-user-rc
393: Allows execution of
394: .Pa ~/.ssh/rc
395: by
396: .Xr sshd 8 .
1.89 jmc 397: .It Ic permit-x11-forwarding
398: Allows X11 forwarding.
399: .It Ic source-address Ns = Ns Ar address_list
1.90 jmc 400: Restrict the source addresses from which the certificate is considered valid.
1.84 djm 401: The
402: .Ar address_list
403: is a comma-separated list of one or more address/netmask pairs in CIDR
404: format.
405: .El
406: .Pp
1.93 djm 407: At present, no options are valid for host keys.
1.66 jmc 408: .It Fl P Ar passphrase
409: Provides the (old) passphrase.
1.2 deraadt 410: .It Fl p
1.1 deraadt 411: Requests changing the passphrase of a private key file instead of
1.12 aaron 412: creating a new private key.
413: The program will prompt for the file
1.1 deraadt 414: containing the private key, for the old passphrase, and twice for the
415: new passphrase.
1.5 aaron 416: .It Fl q
417: Silence
418: .Nm ssh-keygen .
1.64 djm 419: .It Fl R Ar hostname
420: Removes all keys belonging to
421: .Ar hostname
1.65 jmc 422: from a
1.64 djm 423: .Pa known_hosts
424: file.
1.65 jmc 425: This option is useful to delete hashed hosts (see the
1.64 djm 426: .Fl H
427: option above).
1.66 jmc 428: .It Fl r Ar hostname
429: Print the SSHFP fingerprint resource record named
430: .Ar hostname
431: for the specified public key file.
1.60 djm 432: .It Fl S Ar start
433: Specify start point (in hex) when generating candidate moduli for DH-GEX.
1.84 djm 434: .It Fl s Ar ca_key
435: Certify (sign) a public key using the specified CA key.
436: Please see the
437: .Sx CERTIFICATES
438: section for details.
1.60 djm 439: .It Fl T Ar output_file
440: Test DH group exchange candidate primes (generated using the
441: .Fl G
442: option) for safety.
1.66 jmc 443: .It Fl t Ar type
444: Specifies the type of key to create.
445: The possible values are
446: .Dq rsa1
447: for protocol version 1 and
1.100 naddy 448: .Dq dsa ,
449: .Dq ecdsa
450: or
1.66 jmc 451: .Dq rsa
452: for protocol version 2.
1.84 djm 453: .It Fl V Ar validity_interval
454: Specify a validity interval when signing a certificate.
455: A validity interval may consist of a single time, indicating that the
456: certificate is valid beginning now and expiring at that time, or may consist
457: of two times separated by a colon to indicate an explicit time interval.
458: The start time may be specified as a date in YYYYMMDD format, a time
459: in YYYYMMDDHHMMSS format or a relative time (to the current time) consisting
460: of a minus sign followed by a relative time in the format described in the
461: .Sx TIME FORMATS
462: section of
1.90 jmc 463: .Xr sshd_config 5 .
1.84 djm 464: The end time may be specified as a YYYYMMDD date, a YYYYMMDDHHMMSS time or
465: a relative time starting with a plus character.
466: .Pp
467: For example:
468: .Dq +52w1d
469: (valid from now to 52 weeks and one day from now),
470: .Dq -4w:+4w
471: (valid from four weeks ago to four weeks from now),
472: .Dq 20100101123000:20110101123000
473: (valid from 12:30 PM, January 1st, 2010 to 12:30 PM, January 1st, 2011),
474: .Dq -1d:20110101
475: (valid from yesterday to midnight, January 1st, 2011).
1.61 djm 476: .It Fl v
477: Verbose mode.
478: Causes
479: .Nm
480: to print debugging messages about its progress.
481: This is helpful for debugging moduli generation.
482: Multiple
483: .Fl v
484: options increase the verbosity.
485: The maximum is 3.
1.66 jmc 486: .It Fl W Ar generator
487: Specify desired generator when testing candidate moduli for DH-GEX.
488: .It Fl y
489: This option will read a private
490: OpenSSH format file and print an OpenSSH public key to stdout.
1.93 djm 491: .It Fl z Ar serial_number
492: Specifies a serial number to be embedded in the certificate to distinguish
493: this certificate from others from the same CA.
494: The default serial number is zero.
1.2 deraadt 495: .El
1.60 djm 496: .Sh MODULI GENERATION
497: .Nm
498: may be used to generate groups for the Diffie-Hellman Group Exchange
499: (DH-GEX) protocol.
500: Generating these groups is a two-step process: first, candidate
501: primes are generated using a fast, but memory intensive process.
502: These candidate primes are then tested for suitability (a CPU-intensive
503: process).
504: .Pp
505: Generation of primes is performed using the
506: .Fl G
507: option.
508: The desired length of the primes may be specified by the
509: .Fl b
510: option.
511: For example:
512: .Pp
1.66 jmc 513: .Dl # ssh-keygen -G moduli-2048.candidates -b 2048
1.60 djm 514: .Pp
515: By default, the search for primes begins at a random point in the
516: desired length range.
517: This may be overridden using the
518: .Fl S
519: option, which specifies a different start point (in hex).
520: .Pp
521: Once a set of candidates have been generated, they must be tested for
522: suitability.
523: This may be performed using the
524: .Fl T
525: option.
526: In this mode
527: .Nm
528: will read candidates from standard input (or a file specified using the
529: .Fl f
530: option).
531: For example:
532: .Pp
1.66 jmc 533: .Dl # ssh-keygen -T moduli-2048 -f moduli-2048.candidates
1.60 djm 534: .Pp
535: By default, each candidate will be subjected to 100 primality tests.
536: This may be overridden using the
537: .Fl a
538: option.
539: The DH generator value will be chosen automatically for the
540: prime under consideration.
541: If a specific generator is desired, it may be requested using the
542: .Fl W
543: option.
1.66 jmc 544: Valid generator values are 2, 3, and 5.
1.60 djm 545: .Pp
546: Screened DH groups may be installed in
547: .Pa /etc/moduli .
548: It is important that this file contains moduli of a range of bit lengths and
549: that both ends of a connection share common moduli.
1.84 djm 550: .Sh CERTIFICATES
551: .Nm
552: supports signing of keys to produce certificates that may be used for
553: user or host authentication.
554: Certificates consist of a public key, some identity information, zero or
1.94 jmc 555: more principal (user or host) names and a set of options that
1.84 djm 556: are signed by a Certification Authority (CA) key.
557: Clients or servers may then trust only the CA key and verify its signature
558: on a certificate rather than trusting many user/host keys.
559: Note that OpenSSH certificates are a different, and much simpler, format to
560: the X.509 certificates used in
561: .Xr ssl 8 .
562: .Pp
563: .Nm
564: supports two types of certificates: user and host.
565: User certificates authenticate users to servers, whereas host certificates
1.85 jmc 566: authenticate server hosts to users.
567: To generate a user certificate:
1.84 djm 568: .Pp
569: .Dl $ ssh-keygen -s /path/to/ca_key -I key_id /path/to/user_key.pub
570: .Pp
571: The resultant certificate will be placed in
1.91 djm 572: .Pa /path/to/user_key-cert.pub .
1.84 djm 573: A host certificate requires the
574: .Fl h
575: option:
576: .Pp
577: .Dl $ ssh-keygen -s /path/to/ca_key -I key_id -h /path/to/host_key.pub
578: .Pp
579: The host certificate will be output to
1.91 djm 580: .Pa /path/to/host_key-cert.pub .
1.98 djm 581: .Pp
582: It is possible to sign using a CA key stored in a PKCS#11 token by
583: providing the token library using
584: .Fl D
585: and identifying the CA key by providing its public half as an argument
586: to
587: .Fl s :
588: .Pp
589: .Dl $ ssh-keygen -s ca_key.pub -D libpkcs11.so -I key_id host_key.pub
590: .Pp
591: In all cases,
1.84 djm 592: .Ar key_id
593: is a "key identifier" that is logged by the server when the certificate
594: is used for authentication.
595: .Pp
596: Certificates may be limited to be valid for a set of principal (user/host)
597: names.
598: By default, generated certificates are valid for all users or hosts.
599: To generate a certificate for a specified set of principals:
600: .Pp
601: .Dl $ ssh-keygen -s ca_key -I key_id -n user1,user2 user_key.pub
1.92 jmc 602: .Dl "$ ssh-keygen -s ca_key -I key_id -h -n host.domain user_key.pub"
1.84 djm 603: .Pp
604: Additional limitations on the validity and use of user certificates may
1.94 jmc 605: be specified through certificate options.
1.93 djm 606: A certificate option may disable features of the SSH session, may be
1.84 djm 607: valid only when presented from particular source addresses or may
608: force the use of a specific command.
1.93 djm 609: For a list of valid certificate options, see the documentation for the
1.84 djm 610: .Fl O
611: option above.
612: .Pp
613: Finally, certificates may be defined with a validity lifetime.
614: The
615: .Fl V
616: option allows specification of certificate start and end times.
617: A certificate that is presented at a time outside this range will not be
618: considered valid.
619: By default, certificates have a maximum validity interval.
620: .Pp
621: For certificates to be used for user or host authentication, the CA
622: public key must be trusted by
623: .Xr sshd 8
624: or
625: .Xr ssh 1 .
626: Please refer to those manual pages for details.
1.2 deraadt 627: .Sh FILES
1.100 naddy 628: .Bl -tag -width Ds -compact
1.68 djm 629: .It Pa ~/.ssh/identity
1.36 itojun 630: Contains the protocol version 1 RSA authentication identity of the user.
1.12 aaron 631: This file should not be readable by anyone but the user.
632: It is possible to
1.1 deraadt 633: specify a passphrase when generating the key; that passphrase will be
1.100 naddy 634: used to encrypt the private part of this file using 3DES.
1.12 aaron 635: This file is not automatically accessed by
1.2 deraadt 636: .Nm
1.1 deraadt 637: but it is offered as the default file for the private key.
1.46 markus 638: .Xr ssh 1
1.15 deraadt 639: will read this file when a login attempt is made.
1.100 naddy 640: .Pp
1.68 djm 641: .It Pa ~/.ssh/identity.pub
1.36 itojun 642: Contains the protocol version 1 RSA public key for authentication.
1.12 aaron 643: The contents of this file should be added to
1.68 djm 644: .Pa ~/.ssh/authorized_keys
1.2 deraadt 645: on all machines
1.49 deraadt 646: where the user wishes to log in using RSA authentication.
1.15 deraadt 647: There is no need to keep the contents of this file secret.
1.100 naddy 648: .Pp
1.68 djm 649: .It Pa ~/.ssh/id_dsa
1.100 naddy 650: .It Pa ~/.ssh/id_ecdsa
651: .It Pa ~/.ssh/id_rsa
652: Contains the protocol version 2 DSA, ECDSA or RSA authentication identity of the user.
1.15 deraadt 653: This file should not be readable by anyone but the user.
654: It is possible to
655: specify a passphrase when generating the key; that passphrase will be
1.80 dtucker 656: used to encrypt the private part of this file using 128-bit AES.
1.15 deraadt 657: This file is not automatically accessed by
658: .Nm
659: but it is offered as the default file for the private key.
1.46 markus 660: .Xr ssh 1
1.15 deraadt 661: will read this file when a login attempt is made.
1.100 naddy 662: .Pp
1.68 djm 663: .It Pa ~/.ssh/id_dsa.pub
1.100 naddy 664: .It Pa ~/.ssh/id_ecdsa.pub
1.68 djm 665: .It Pa ~/.ssh/id_rsa.pub
1.100 naddy 666: Contains the protocol version 2 DSA, ECDSA or RSA public key for authentication.
1.15 deraadt 667: The contents of this file should be added to
1.68 djm 668: .Pa ~/.ssh/authorized_keys
1.15 deraadt 669: on all machines
1.49 deraadt 670: where the user wishes to log in using public key authentication.
1.12 aaron 671: There is no need to keep the contents of this file secret.
1.100 naddy 672: .Pp
1.60 djm 673: .It Pa /etc/moduli
674: Contains Diffie-Hellman groups used for DH-GEX.
675: The file format is described in
676: .Xr moduli 5 .
1.19 aaron 677: .El
1.2 deraadt 678: .Sh SEE ALSO
679: .Xr ssh 1 ,
680: .Xr ssh-add 1 ,
1.8 ericj 681: .Xr ssh-agent 1 ,
1.60 djm 682: .Xr moduli 5 ,
1.30 itojun 683: .Xr sshd 8
1.37 markus 684: .Rs
1.73 markus 685: .%R RFC 4716
686: .%T "The Secure Shell (SSH) Public Key File Format"
687: .%D 2006
1.37 markus 688: .Re
1.59 jmc 689: .Sh AUTHORS
690: OpenSSH is a derivative of the original and free
691: ssh 1.2.12 release by Tatu Ylonen.
692: Aaron Campbell, Bob Beck, Markus Friedl, Niels Provos,
693: Theo de Raadt and Dug Song
694: removed many bugs, re-added newer features and
695: created OpenSSH.
696: Markus Friedl contributed the support for SSH
697: protocol versions 1.5 and 2.0.
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