Annotation of src/usr.bin/ssh/ssh-keygen.1, Revision 1.106
1.106 ! djm 1: .\" $OpenBSD: ssh-keygen.1,v 1.105 2011/04/13 04:02:48 djm 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,
33: .\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
34: .\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
35: .\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
36: .\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
1.1 deraadt 37: .\"
1.106 ! djm 38: .Dd $Mdocdate: April 13 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
107: .Op Fl W Ar generator
1.84 djm 108: .Nm ssh-keygen
109: .Fl s Ar ca_key
110: .Fl I Ar certificate_identity
111: .Op Fl h
112: .Op Fl n Ar principals
1.93 djm 113: .Op Fl O Ar option
1.84 djm 114: .Op Fl V Ar validity_interval
1.93 djm 115: .Op Fl z Ar serial_number
1.84 djm 116: .Ar
1.86 djm 117: .Nm ssh-keygen
118: .Fl L
119: .Op Fl f Ar input_keyfile
1.102 stevesk 120: .Nm ssh-keygen
121: .Fl A
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
1.100 naddy 128: can create RSA keys for use by SSH protocol version 1 and DSA, ECDSA or RSA
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.
1.105 djm 178: If the passphrase is lost or forgotten, a new key must be generated
179: and the corresponding public key copied to other machines.
1.2 deraadt 180: .Pp
1.37 markus 181: For RSA1 keys,
182: there is also a comment field in the key file that is only for
1.12 aaron 183: convenience to the user to help identify the key.
184: The comment can tell what the key is for, or whatever is useful.
185: The comment is initialized to
1.2 deraadt 186: .Dq user@host
187: when the key is created, but can be changed using the
188: .Fl c
1.1 deraadt 189: option.
1.2 deraadt 190: .Pp
1.15 deraadt 191: After a key is generated, instructions below detail where the keys
192: should be placed to be activated.
193: .Pp
1.2 deraadt 194: The options are as follows:
195: .Bl -tag -width Ds
1.102 stevesk 196: .It Fl A
197: For each of the key types (rsa1, rsa, dsa and ecdsa) for which host keys
198: do not exist, generate the host keys with the default key file path,
199: an empty passphrase, default bits for the key type, and default comment.
1.104 jmc 200: This is used by
1.102 stevesk 201: .Pa /etc/rc
202: to generate new host keys.
1.60 djm 203: .It Fl a Ar trials
204: Specifies the number of primality tests to perform when screening DH-GEX
205: candidates using the
206: .Fl T
207: command.
1.66 jmc 208: .It Fl B
209: Show the bubblebabble digest of specified private or public key file.
1.2 deraadt 210: .It Fl b Ar bits
1.12 aaron 211: Specifies the number of bits in the key to create.
1.72 dtucker 212: For RSA keys, the minimum size is 768 bits and the default is 2048 bits.
1.69 djm 213: Generally, 2048 bits is considered sufficient.
1.72 dtucker 214: DSA keys must be exactly 1024 bits as specified by FIPS 186-2.
1.106 ! djm 215: For ECDSA keys, the
! 216: .Fl b
! 217: flag determines they key length by selecting from one of three elliptic
! 218: curve sizes: 256, 384 or 521 bits.
! 219: Attempting to use bit lengths other than these three values for ECDSA keys
! 220: will fail.
1.66 jmc 221: .It Fl C Ar comment
222: Provides a new comment.
1.2 deraadt 223: .It Fl c
1.1 deraadt 224: Requests changing the comment in the private and public key files.
1.50 markus 225: This operation is only supported for RSA1 keys.
1.1 deraadt 226: The program will prompt for the file containing the private keys, for
1.41 stevesk 227: the passphrase if the key has one, and for the new comment.
1.81 markus 228: .It Fl D Ar pkcs11
1.83 markus 229: Download the RSA public keys provided by the PKCS#11 shared library
230: .Ar pkcs11 .
1.98 djm 231: When used in combination with
232: .Fl s ,
233: this option indicates that a CA key resides in a PKCS#11 token (see the
234: .Sx CERTIFICATES
235: section for details).
1.37 markus 236: .It Fl e
1.40 markus 237: This option will read a private or public OpenSSH key file and
1.95 djm 238: print to stdout the key in one of the formats specified by the
239: .Fl m
240: option.
241: The default export format is
242: .Dq RFC4716 .
1.96 jmc 243: This option allows exporting OpenSSH keys for use by other programs, including
1.95 djm 244: several commercial SSH implementations.
1.66 jmc 245: .It Fl F Ar hostname
246: Search for the specified
247: .Ar hostname
248: in a
249: .Pa known_hosts
250: file, listing any occurrences found.
251: This option is useful to find hashed host names or addresses and may also be
252: used in conjunction with the
253: .Fl H
254: option to print found keys in a hashed format.
255: .It Fl f Ar filename
256: Specifies the filename of the key file.
257: .It Fl G Ar output_file
258: Generate candidate primes for DH-GEX.
259: These primes must be screened for
260: safety (using the
261: .Fl T
262: option) before use.
1.57 jakob 263: .It Fl g
1.62 jakob 264: Use generic DNS format when printing fingerprint resource records using the
1.63 jmc 265: .Fl r
1.62 jakob 266: command.
1.66 jmc 267: .It Fl H
268: Hash a
269: .Pa known_hosts
1.67 dtucker 270: file.
271: This replaces all hostnames and addresses with hashed representations
272: within the specified file; the original content is moved to a file with
273: a .old suffix.
1.66 jmc 274: These hashes may be used normally by
275: .Nm ssh
276: and
277: .Nm sshd ,
278: but they do not reveal identifying information should the file's contents
279: be disclosed.
280: This option will not modify existing hashed hostnames and is therefore safe
281: to use on files that mix hashed and non-hashed names.
1.84 djm 282: .It Fl h
283: When signing a key, create a host certificate instead of a user
284: certificate.
285: Please see the
286: .Sx CERTIFICATES
287: section for details.
1.85 jmc 288: .It Fl I Ar certificate_identity
1.84 djm 289: Specify the key identity when signing a public key.
290: Please see the
291: .Sx CERTIFICATES
292: section for details.
1.37 markus 293: .It Fl i
294: This option will read an unencrypted private (or public) key file
1.95 djm 295: in the format specified by the
296: .Fl m
297: option and print an OpenSSH compatible private
1.37 markus 298: (or public) key to stdout.
1.95 djm 299: This option allows importing keys from other software, including several
300: commercial SSH implementations.
301: The default import format is
302: .Dq RFC4716 .
1.86 djm 303: .It Fl L
304: Prints the contents of a certificate.
1.9 markus 305: .It Fl l
1.77 grunk 306: Show fingerprint of specified public key file.
1.50 markus 307: Private RSA1 keys are also supported.
308: For RSA and DSA keys
309: .Nm
1.78 jmc 310: tries to find the matching public key file and prints its fingerprint.
311: If combined with
312: .Fl v ,
313: an ASCII art representation of the key is supplied with the fingerprint.
1.96 jmc 314: .It Fl M Ar memory
315: Specify the amount of memory to use (in megabytes) when generating
316: candidate moduli for DH-GEX.
1.95 djm 317: .It Fl m Ar key_format
318: Specify a key format for the
319: .Fl i
320: (import) or
321: .Fl e
1.96 jmc 322: (export) conversion options.
1.95 djm 323: The supported key formats are:
324: .Dq RFC4716
1.96 jmc 325: (RFC 4716/SSH2 public or private key),
1.95 djm 326: .Dq PKCS8
327: (PEM PKCS8 public key)
328: or
329: .Dq PEM
330: (PEM public key).
331: The default conversion format is
332: .Dq RFC4716 .
1.66 jmc 333: .It Fl N Ar new_passphrase
334: Provides the new passphrase.
1.84 djm 335: .It Fl n Ar principals
336: Specify one or more principals (user or host names) to be included in
337: a certificate when signing a key.
338: Multiple principals may be specified, separated by commas.
339: Please see the
340: .Sx CERTIFICATES
341: section for details.
1.93 djm 342: .It Fl O Ar option
343: Specify a certificate option when signing a key.
1.84 djm 344: This option may be specified multiple times.
345: Please see the
346: .Sx CERTIFICATES
347: section for details.
1.93 djm 348: The options that are valid for user certificates are:
1.84 djm 349: .Bl -tag -width Ds
1.89 jmc 350: .It Ic clear
351: Clear all enabled permissions.
352: This is useful for clearing the default set of permissions so permissions may
353: be added individually.
354: .It Ic force-command Ns = Ns Ar command
355: Forces the execution of
356: .Ar command
357: instead of any shell or command specified by the user when
358: the certificate is used for authentication.
1.84 djm 359: .It Ic no-agent-forwarding
360: Disable
361: .Xr ssh-agent 1
1.85 jmc 362: forwarding (permitted by default).
1.84 djm 363: .It Ic no-port-forwarding
1.85 jmc 364: Disable port forwarding (permitted by default).
1.84 djm 365: .It Ic no-pty
1.85 jmc 366: Disable PTY allocation (permitted by default).
1.84 djm 367: .It Ic no-user-rc
368: Disable execution of
369: .Pa ~/.ssh/rc
370: by
1.85 jmc 371: .Xr sshd 8
372: (permitted by default).
1.89 jmc 373: .It Ic no-x11-forwarding
374: Disable X11 forwarding (permitted by default).
1.88 djm 375: .It Ic permit-agent-forwarding
376: Allows
377: .Xr ssh-agent 1
378: forwarding.
1.84 djm 379: .It Ic permit-port-forwarding
380: Allows port forwarding.
381: .It Ic permit-pty
382: Allows PTY allocation.
383: .It Ic permit-user-rc
384: Allows execution of
385: .Pa ~/.ssh/rc
386: by
387: .Xr sshd 8 .
1.89 jmc 388: .It Ic permit-x11-forwarding
389: Allows X11 forwarding.
390: .It Ic source-address Ns = Ns Ar address_list
1.90 jmc 391: Restrict the source addresses from which the certificate is considered valid.
1.84 djm 392: The
393: .Ar address_list
394: is a comma-separated list of one or more address/netmask pairs in CIDR
395: format.
396: .El
397: .Pp
1.93 djm 398: At present, no options are valid for host keys.
1.66 jmc 399: .It Fl P Ar passphrase
400: Provides the (old) passphrase.
1.2 deraadt 401: .It Fl p
1.1 deraadt 402: Requests changing the passphrase of a private key file instead of
1.12 aaron 403: creating a new private key.
404: The program will prompt for the file
1.1 deraadt 405: containing the private key, for the old passphrase, and twice for the
406: new passphrase.
1.5 aaron 407: .It Fl q
408: Silence
409: .Nm ssh-keygen .
1.64 djm 410: .It Fl R Ar hostname
411: Removes all keys belonging to
412: .Ar hostname
1.65 jmc 413: from a
1.64 djm 414: .Pa known_hosts
415: file.
1.65 jmc 416: This option is useful to delete hashed hosts (see the
1.64 djm 417: .Fl H
418: option above).
1.66 jmc 419: .It Fl r Ar hostname
420: Print the SSHFP fingerprint resource record named
421: .Ar hostname
422: for the specified public key file.
1.60 djm 423: .It Fl S Ar start
424: Specify start point (in hex) when generating candidate moduli for DH-GEX.
1.84 djm 425: .It Fl s Ar ca_key
426: Certify (sign) a public key using the specified CA key.
427: Please see the
428: .Sx CERTIFICATES
429: section for details.
1.60 djm 430: .It Fl T Ar output_file
431: Test DH group exchange candidate primes (generated using the
432: .Fl G
433: option) for safety.
1.66 jmc 434: .It Fl t Ar type
435: Specifies the type of key to create.
436: The possible values are
437: .Dq rsa1
438: for protocol version 1 and
1.100 naddy 439: .Dq dsa ,
440: .Dq ecdsa
441: or
1.66 jmc 442: .Dq rsa
443: for protocol version 2.
1.84 djm 444: .It Fl V Ar validity_interval
445: Specify a validity interval when signing a certificate.
446: A validity interval may consist of a single time, indicating that the
447: certificate is valid beginning now and expiring at that time, or may consist
448: of two times separated by a colon to indicate an explicit time interval.
449: The start time may be specified as a date in YYYYMMDD format, a time
450: in YYYYMMDDHHMMSS format or a relative time (to the current time) consisting
451: of a minus sign followed by a relative time in the format described in the
452: .Sx TIME FORMATS
453: section of
1.90 jmc 454: .Xr sshd_config 5 .
1.84 djm 455: The end time may be specified as a YYYYMMDD date, a YYYYMMDDHHMMSS time or
456: a relative time starting with a plus character.
457: .Pp
458: For example:
459: .Dq +52w1d
460: (valid from now to 52 weeks and one day from now),
461: .Dq -4w:+4w
462: (valid from four weeks ago to four weeks from now),
463: .Dq 20100101123000:20110101123000
464: (valid from 12:30 PM, January 1st, 2010 to 12:30 PM, January 1st, 2011),
465: .Dq -1d:20110101
466: (valid from yesterday to midnight, January 1st, 2011).
1.61 djm 467: .It Fl v
468: Verbose mode.
469: Causes
470: .Nm
471: to print debugging messages about its progress.
472: This is helpful for debugging moduli generation.
473: Multiple
474: .Fl v
475: options increase the verbosity.
476: The maximum is 3.
1.66 jmc 477: .It Fl W Ar generator
478: Specify desired generator when testing candidate moduli for DH-GEX.
479: .It Fl y
480: This option will read a private
481: OpenSSH format file and print an OpenSSH public key to stdout.
1.93 djm 482: .It Fl z Ar serial_number
483: Specifies a serial number to be embedded in the certificate to distinguish
484: this certificate from others from the same CA.
485: The default serial number is zero.
1.2 deraadt 486: .El
1.60 djm 487: .Sh MODULI GENERATION
488: .Nm
489: may be used to generate groups for the Diffie-Hellman Group Exchange
490: (DH-GEX) protocol.
491: Generating these groups is a two-step process: first, candidate
492: primes are generated using a fast, but memory intensive process.
493: These candidate primes are then tested for suitability (a CPU-intensive
494: process).
495: .Pp
496: Generation of primes is performed using the
497: .Fl G
498: option.
499: The desired length of the primes may be specified by the
500: .Fl b
501: option.
502: For example:
503: .Pp
1.66 jmc 504: .Dl # ssh-keygen -G moduli-2048.candidates -b 2048
1.60 djm 505: .Pp
506: By default, the search for primes begins at a random point in the
507: desired length range.
508: This may be overridden using the
509: .Fl S
510: option, which specifies a different start point (in hex).
511: .Pp
512: Once a set of candidates have been generated, they must be tested for
513: suitability.
514: This may be performed using the
515: .Fl T
516: option.
517: In this mode
518: .Nm
519: will read candidates from standard input (or a file specified using the
520: .Fl f
521: option).
522: For example:
523: .Pp
1.66 jmc 524: .Dl # ssh-keygen -T moduli-2048 -f moduli-2048.candidates
1.60 djm 525: .Pp
526: By default, each candidate will be subjected to 100 primality tests.
527: This may be overridden using the
528: .Fl a
529: option.
530: The DH generator value will be chosen automatically for the
531: prime under consideration.
532: If a specific generator is desired, it may be requested using the
533: .Fl W
534: option.
1.66 jmc 535: Valid generator values are 2, 3, and 5.
1.60 djm 536: .Pp
537: Screened DH groups may be installed in
538: .Pa /etc/moduli .
539: It is important that this file contains moduli of a range of bit lengths and
540: that both ends of a connection share common moduli.
1.84 djm 541: .Sh CERTIFICATES
542: .Nm
543: supports signing of keys to produce certificates that may be used for
544: user or host authentication.
545: Certificates consist of a public key, some identity information, zero or
1.94 jmc 546: more principal (user or host) names and a set of options that
1.84 djm 547: are signed by a Certification Authority (CA) key.
548: Clients or servers may then trust only the CA key and verify its signature
549: on a certificate rather than trusting many user/host keys.
550: Note that OpenSSH certificates are a different, and much simpler, format to
551: the X.509 certificates used in
552: .Xr ssl 8 .
553: .Pp
554: .Nm
555: supports two types of certificates: user and host.
556: User certificates authenticate users to servers, whereas host certificates
1.85 jmc 557: authenticate server hosts to users.
558: To generate a user certificate:
1.84 djm 559: .Pp
560: .Dl $ ssh-keygen -s /path/to/ca_key -I key_id /path/to/user_key.pub
561: .Pp
562: The resultant certificate will be placed in
1.91 djm 563: .Pa /path/to/user_key-cert.pub .
1.84 djm 564: A host certificate requires the
565: .Fl h
566: option:
567: .Pp
568: .Dl $ ssh-keygen -s /path/to/ca_key -I key_id -h /path/to/host_key.pub
569: .Pp
570: The host certificate will be output to
1.91 djm 571: .Pa /path/to/host_key-cert.pub .
1.98 djm 572: .Pp
573: It is possible to sign using a CA key stored in a PKCS#11 token by
574: providing the token library using
575: .Fl D
576: and identifying the CA key by providing its public half as an argument
577: to
578: .Fl s :
579: .Pp
580: .Dl $ ssh-keygen -s ca_key.pub -D libpkcs11.so -I key_id host_key.pub
581: .Pp
582: In all cases,
1.84 djm 583: .Ar key_id
584: is a "key identifier" that is logged by the server when the certificate
585: is used for authentication.
586: .Pp
587: Certificates may be limited to be valid for a set of principal (user/host)
588: names.
589: By default, generated certificates are valid for all users or hosts.
590: To generate a certificate for a specified set of principals:
591: .Pp
592: .Dl $ ssh-keygen -s ca_key -I key_id -n user1,user2 user_key.pub
1.92 jmc 593: .Dl "$ ssh-keygen -s ca_key -I key_id -h -n host.domain user_key.pub"
1.84 djm 594: .Pp
595: Additional limitations on the validity and use of user certificates may
1.94 jmc 596: be specified through certificate options.
1.93 djm 597: A certificate option may disable features of the SSH session, may be
1.84 djm 598: valid only when presented from particular source addresses or may
599: force the use of a specific command.
1.93 djm 600: For a list of valid certificate options, see the documentation for the
1.84 djm 601: .Fl O
602: option above.
603: .Pp
604: Finally, certificates may be defined with a validity lifetime.
605: The
606: .Fl V
607: option allows specification of certificate start and end times.
608: A certificate that is presented at a time outside this range will not be
609: considered valid.
610: By default, certificates have a maximum validity interval.
611: .Pp
612: For certificates to be used for user or host authentication, the CA
613: public key must be trusted by
614: .Xr sshd 8
615: or
616: .Xr ssh 1 .
617: Please refer to those manual pages for details.
1.2 deraadt 618: .Sh FILES
1.100 naddy 619: .Bl -tag -width Ds -compact
1.68 djm 620: .It Pa ~/.ssh/identity
1.36 itojun 621: Contains the protocol version 1 RSA authentication identity of the user.
1.12 aaron 622: This file should not be readable by anyone but the user.
623: It is possible to
1.1 deraadt 624: specify a passphrase when generating the key; that passphrase will be
1.100 naddy 625: used to encrypt the private part of this file using 3DES.
1.12 aaron 626: This file is not automatically accessed by
1.2 deraadt 627: .Nm
1.1 deraadt 628: but it is offered as the default file for the private key.
1.46 markus 629: .Xr ssh 1
1.15 deraadt 630: will read this file when a login attempt is made.
1.100 naddy 631: .Pp
1.68 djm 632: .It Pa ~/.ssh/identity.pub
1.36 itojun 633: Contains the protocol version 1 RSA public key for authentication.
1.12 aaron 634: The contents of this file should be added to
1.68 djm 635: .Pa ~/.ssh/authorized_keys
1.2 deraadt 636: on all machines
1.49 deraadt 637: where the user wishes to log in using RSA authentication.
1.15 deraadt 638: There is no need to keep the contents of this file secret.
1.100 naddy 639: .Pp
1.68 djm 640: .It Pa ~/.ssh/id_dsa
1.100 naddy 641: .It Pa ~/.ssh/id_ecdsa
642: .It Pa ~/.ssh/id_rsa
643: Contains the protocol version 2 DSA, ECDSA or RSA authentication identity of the user.
1.15 deraadt 644: This file should not be readable by anyone but the user.
645: It is possible to
646: specify a passphrase when generating the key; that passphrase will be
1.80 dtucker 647: used to encrypt the private part of this file using 128-bit AES.
1.15 deraadt 648: This file is not automatically accessed by
649: .Nm
650: but it is offered as the default file for the private key.
1.46 markus 651: .Xr ssh 1
1.15 deraadt 652: will read this file when a login attempt is made.
1.100 naddy 653: .Pp
1.68 djm 654: .It Pa ~/.ssh/id_dsa.pub
1.100 naddy 655: .It Pa ~/.ssh/id_ecdsa.pub
1.68 djm 656: .It Pa ~/.ssh/id_rsa.pub
1.100 naddy 657: Contains the protocol version 2 DSA, ECDSA or RSA public key for authentication.
1.15 deraadt 658: The contents of this file should be added to
1.68 djm 659: .Pa ~/.ssh/authorized_keys
1.15 deraadt 660: on all machines
1.49 deraadt 661: where the user wishes to log in using public key authentication.
1.12 aaron 662: There is no need to keep the contents of this file secret.
1.100 naddy 663: .Pp
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.
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