Annotation of src/usr.bin/ssh/ssh-keygen.1, Revision 1.192
1.192 ! naddy 1: .\" $OpenBSD: ssh-keygen.1,v 1.191 2020/01/14 15:07:30 naddy 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: .\"
1.192 ! naddy 38: .Dd $Mdocdate: January 14 2020 $
1.2 deraadt 39: .Dt SSH-KEYGEN 1
40: .Os
41: .Sh NAME
42: .Nm ssh-keygen
1.179 jmc 43: .Nd OpenSSH authentication key utility
1.2 deraadt 44: .Sh SYNOPSIS
45: .Nm ssh-keygen
1.25 markus 46: .Op Fl q
1.2 deraadt 47: .Op Fl b Ar bits
48: .Op Fl C Ar comment
1.20 markus 49: .Op Fl f Ar output_keyfile
1.155 djm 50: .Op Fl m Ar format
1.175 djm 51: .Op Fl t Cm dsa | ecdsa | ecdsa-sk | ed25519 | ed25519-sk | rsa
1.171 jmc 52: .Op Fl N Ar new_passphrase
1.191 naddy 53: .Op Fl O Ar option
1.173 naddy 54: .Op Fl w Ar provider
1.2 deraadt 55: .Nm ssh-keygen
56: .Fl p
1.9 markus 57: .Op Fl f Ar keyfile
1.155 djm 58: .Op Fl m Ar format
1.171 jmc 59: .Op Fl N Ar new_passphrase
60: .Op Fl P Ar old_passphrase
1.2 deraadt 61: .Nm ssh-keygen
1.37 markus 62: .Fl i
1.171 jmc 63: .Op Fl f Ar input_keyfile
1.95 djm 64: .Op Fl m Ar key_format
1.16 deraadt 65: .Nm ssh-keygen
1.37 markus 66: .Fl e
1.171 jmc 67: .Op Fl f Ar input_keyfile
1.95 djm 68: .Op Fl m Ar key_format
1.16 deraadt 69: .Nm ssh-keygen
1.17 markus 70: .Fl y
1.20 markus 71: .Op Fl f Ar input_keyfile
1.17 markus 72: .Nm ssh-keygen
1.2 deraadt 73: .Fl c
74: .Op Fl C Ar comment
1.9 markus 75: .Op Fl f Ar keyfile
1.171 jmc 76: .Op Fl P Ar passphrase
1.9 markus 77: .Nm ssh-keygen
78: .Fl l
1.125 naddy 79: .Op Fl v
1.124 djm 80: .Op Fl E Ar fingerprint_hash
1.35 markus 81: .Op Fl f Ar input_keyfile
82: .Nm ssh-keygen
83: .Fl B
1.20 markus 84: .Op Fl f Ar input_keyfile
1.48 jakob 85: .Nm ssh-keygen
1.82 jmc 86: .Fl D Ar pkcs11
1.48 jakob 87: .Nm ssh-keygen
1.64 djm 88: .Fl F Ar hostname
1.170 jmc 89: .Op Fl lv
1.64 djm 90: .Op Fl f Ar known_hosts_file
91: .Nm ssh-keygen
92: .Fl H
93: .Op Fl f Ar known_hosts_file
94: .Nm ssh-keygen
1.187 djm 95: .Fl K
96: .Op Fl w Ar provider
97: .Nm ssh-keygen
1.64 djm 98: .Fl R Ar hostname
99: .Op Fl f Ar known_hosts_file
1.57 jakob 100: .Nm ssh-keygen
101: .Fl r Ar hostname
1.170 jmc 102: .Op Fl g
1.57 jakob 103: .Op Fl f Ar input_keyfile
1.60 djm 104: .Nm ssh-keygen
1.184 djm 105: .Fl M Cm generate
106: .Op Fl O Ar option
1.191 naddy 107: .Ar output_file
1.60 djm 108: .Nm ssh-keygen
1.184 djm 109: .Fl M Cm screen
1.191 naddy 110: .Op Fl f Ar input_file
1.184 djm 111: .Op Fl O Ar option
1.191 naddy 112: .Ar output_file
1.84 djm 113: .Nm ssh-keygen
1.171 jmc 114: .Fl I Ar certificate_identity
1.84 djm 115: .Fl s Ar ca_key
1.170 jmc 116: .Op Fl hU
1.142 djm 117: .Op Fl D Ar pkcs11_provider
1.84 djm 118: .Op Fl n Ar principals
1.93 djm 119: .Op Fl O Ar option
1.84 djm 120: .Op Fl V Ar validity_interval
1.93 djm 121: .Op Fl z Ar serial_number
1.84 djm 122: .Ar
1.86 djm 123: .Nm ssh-keygen
124: .Fl L
125: .Op Fl f Ar input_keyfile
1.102 stevesk 126: .Nm ssh-keygen
127: .Fl A
1.143 djm 128: .Op Fl f Ar prefix_path
1.111 djm 129: .Nm ssh-keygen
130: .Fl k
131: .Fl f Ar krl_file
132: .Op Fl u
1.112 jmc 133: .Op Fl s Ar ca_public
134: .Op Fl z Ar version_number
1.111 djm 135: .Ar
136: .Nm ssh-keygen
137: .Fl Q
138: .Fl f Ar krl_file
139: .Ar
1.163 djm 140: .Nm ssh-keygen
1.171 jmc 141: .Fl Y Cm check-novalidate
142: .Fl n Ar namespace
143: .Fl s Ar signature_file
144: .Nm ssh-keygen
1.163 djm 145: .Fl Y Cm sign
146: .Fl f Ar key_file
147: .Fl n Ar namespace
148: .Ar
149: .Nm ssh-keygen
150: .Fl Y Cm verify
1.171 jmc 151: .Fl f Ar allowed_signers_file
1.163 djm 152: .Fl I Ar signer_identity
153: .Fl n Ar namespace
154: .Fl s Ar signature_file
155: .Op Fl r Ar revocation_file
1.13 aaron 156: .Sh DESCRIPTION
1.2 deraadt 157: .Nm
1.37 markus 158: generates, manages and converts authentication keys for
1.2 deraadt 159: .Xr ssh 1 .
1.15 deraadt 160: .Nm
1.140 jmc 161: can create keys for use by SSH protocol version 2.
1.130 jmc 162: .Pp
1.58 jmc 163: The type of key to be generated is specified with the
1.25 markus 164: .Fl t
1.52 djm 165: option.
1.70 djm 166: If invoked without any arguments,
167: .Nm
1.141 naddy 168: will generate an RSA key.
1.15 deraadt 169: .Pp
1.60 djm 170: .Nm
171: is also used to generate groups for use in Diffie-Hellman group
172: exchange (DH-GEX).
173: See the
174: .Sx MODULI GENERATION
175: section for details.
176: .Pp
1.111 djm 177: Finally,
178: .Nm
179: can be used to generate and update Key Revocation Lists, and to test whether
1.112 jmc 180: given keys have been revoked by one.
181: See the
1.111 djm 182: .Sx KEY REVOCATION LISTS
183: section for details.
184: .Pp
1.2 deraadt 185: Normally each user wishing to use SSH
1.99 djm 186: with public key authentication runs this once to create the authentication
1.1 deraadt 187: key in
1.118 naddy 188: .Pa ~/.ssh/id_dsa ,
1.99 djm 189: .Pa ~/.ssh/id_ecdsa ,
1.173 naddy 190: .Pa ~/.ssh/id_ecdsa_sk ,
1.176 naddy 191: .Pa ~/.ssh/id_ed25519 ,
192: .Pa ~/.ssh/id_ed25519_sk
1.15 deraadt 193: or
1.68 djm 194: .Pa ~/.ssh/id_rsa .
1.15 deraadt 195: Additionally, the system administrator may use this to generate host keys,
196: as seen in
197: .Pa /etc/rc .
1.2 deraadt 198: .Pp
1.1 deraadt 199: Normally this program generates the key and asks for a file in which
1.12 aaron 200: to store the private key.
201: The public key is stored in a file with the same name but
1.2 deraadt 202: .Dq .pub
1.12 aaron 203: appended.
204: The program also asks for a passphrase.
205: The passphrase may be empty to indicate no passphrase
1.26 markus 206: (host keys must have an empty passphrase), or it may be a string of
1.12 aaron 207: arbitrary length.
1.51 stevesk 208: A passphrase is similar to a password, except it can be a phrase with a
209: series of words, punctuation, numbers, whitespace, or any string of
210: characters you want.
211: Good passphrases are 10-30 characters long, are
1.1 deraadt 212: not simple sentences or otherwise easily guessable (English
1.42 markus 213: prose has only 1-2 bits of entropy per character, and provides very bad
1.51 stevesk 214: passphrases), and contain a mix of upper and lowercase letters,
215: numbers, and non-alphanumeric characters.
1.12 aaron 216: The passphrase can be changed later by using the
1.2 deraadt 217: .Fl p
1.1 deraadt 218: option.
1.2 deraadt 219: .Pp
1.12 aaron 220: There is no way to recover a lost passphrase.
1.105 djm 221: If the passphrase is lost or forgotten, a new key must be generated
222: and the corresponding public key copied to other machines.
1.2 deraadt 223: .Pp
1.153 djm 224: .Nm
225: will by default write keys in an OpenSSH-specific format.
226: This format is preferred as it offers better protection for
227: keys at rest as well as allowing storage of key comments within
228: the private key file itself.
229: The key comment may be useful to help identify the key.
1.12 aaron 230: The comment is initialized to
1.2 deraadt 231: .Dq user@host
232: when the key is created, but can be changed using the
233: .Fl c
1.1 deraadt 234: option.
1.153 djm 235: .Pp
236: It is still possible for
237: .Nm
238: to write the previously-used PEM format private keys using the
239: .Fl m
240: flag.
241: This may be used when generating new keys, and existing new-format
242: keys may be converted using this option in conjunction with the
243: .Fl p
244: (change passphrase) flag.
1.2 deraadt 245: .Pp
1.15 deraadt 246: After a key is generated, instructions below detail where the keys
247: should be placed to be activated.
248: .Pp
1.2 deraadt 249: The options are as follows:
250: .Bl -tag -width Ds
1.102 stevesk 251: .It Fl A
1.175 djm 252: For each of the key types (rsa, dsa, ecdsa and ed25519)
1.118 naddy 253: for which host keys
1.102 stevesk 254: do not exist, generate the host keys with the default key file path,
255: an empty passphrase, default bits for the key type, and default comment.
1.144 jmc 256: If
1.143 djm 257: .Fl f
1.144 jmc 258: has also been specified, its argument is used as a prefix to the
1.143 djm 259: default path for the resulting host key files.
1.104 jmc 260: This is used by
1.102 stevesk 261: .Pa /etc/rc
262: to generate new host keys.
1.117 djm 263: .It Fl a Ar rounds
1.169 jmc 264: When saving a private key, this option specifies the number of KDF
1.148 djm 265: (key derivation function) rounds used.
1.117 djm 266: Higher numbers result in slower passphrase verification and increased
267: resistance to brute-force password cracking (should the keys be stolen).
1.66 jmc 268: .It Fl B
269: Show the bubblebabble digest of specified private or public key file.
1.2 deraadt 270: .It Fl b Ar bits
1.12 aaron 271: Specifies the number of bits in the key to create.
1.158 dtucker 272: For RSA keys, the minimum size is 1024 bits and the default is 3072 bits.
273: Generally, 3072 bits is considered sufficient.
1.72 dtucker 274: DSA keys must be exactly 1024 bits as specified by FIPS 186-2.
1.106 djm 275: For ECDSA keys, the
276: .Fl b
1.107 deraadt 277: flag determines the key length by selecting from one of three elliptic
1.106 djm 278: curve sizes: 256, 384 or 521 bits.
279: Attempting to use bit lengths other than these three values for ECDSA keys
280: will fail.
1.176 naddy 281: ECDSA-SK, Ed25519 and Ed25519-SK keys have a fixed length and the
1.118 naddy 282: .Fl b
283: flag will be ignored.
1.66 jmc 284: .It Fl C Ar comment
285: Provides a new comment.
1.2 deraadt 286: .It Fl c
1.1 deraadt 287: Requests changing the comment in the private and public key files.
288: The program will prompt for the file containing the private keys, for
1.41 stevesk 289: the passphrase if the key has one, and for the new comment.
1.81 markus 290: .It Fl D Ar pkcs11
1.157 naddy 291: Download the public keys provided by the PKCS#11 shared library
1.83 markus 292: .Ar pkcs11 .
1.98 djm 293: When used in combination with
294: .Fl s ,
295: this option indicates that a CA key resides in a PKCS#11 token (see the
296: .Sx CERTIFICATES
297: section for details).
1.124 djm 298: .It Fl E Ar fingerprint_hash
299: Specifies the hash algorithm used when displaying key fingerprints.
300: Valid options are:
301: .Dq md5
302: and
303: .Dq sha256 .
304: The default is
305: .Dq sha256 .
1.37 markus 306: .It Fl e
1.40 markus 307: This option will read a private or public OpenSSH key file and
1.154 djm 308: print to stdout a public key in one of the formats specified by the
1.95 djm 309: .Fl m
310: option.
311: The default export format is
312: .Dq RFC4716 .
1.96 jmc 313: This option allows exporting OpenSSH keys for use by other programs, including
1.95 djm 314: several commercial SSH implementations.
1.151 djm 315: .It Fl F Ar hostname | [hostname]:port
1.66 jmc 316: Search for the specified
317: .Ar hostname
1.151 djm 318: (with optional port number)
1.66 jmc 319: in a
320: .Pa known_hosts
321: file, listing any occurrences found.
322: This option is useful to find hashed host names or addresses and may also be
323: used in conjunction with the
324: .Fl H
325: option to print found keys in a hashed format.
326: .It Fl f Ar filename
327: Specifies the filename of the key file.
1.57 jakob 328: .It Fl g
1.62 jakob 329: Use generic DNS format when printing fingerprint resource records using the
1.63 jmc 330: .Fl r
1.62 jakob 331: command.
1.66 jmc 332: .It Fl H
333: Hash a
334: .Pa known_hosts
1.67 dtucker 335: file.
336: This replaces all hostnames and addresses with hashed representations
337: within the specified file; the original content is moved to a file with
338: a .old suffix.
1.66 jmc 339: These hashes may be used normally by
340: .Nm ssh
341: and
342: .Nm sshd ,
343: but they do not reveal identifying information should the file's contents
344: be disclosed.
345: This option will not modify existing hashed hostnames and is therefore safe
346: to use on files that mix hashed and non-hashed names.
1.84 djm 347: .It Fl h
348: When signing a key, create a host certificate instead of a user
349: certificate.
350: Please see the
351: .Sx CERTIFICATES
352: section for details.
1.85 jmc 353: .It Fl I Ar certificate_identity
1.84 djm 354: Specify the key identity when signing a public key.
355: Please see the
356: .Sx CERTIFICATES
357: section for details.
1.37 markus 358: .It Fl i
359: This option will read an unencrypted private (or public) key file
1.95 djm 360: in the format specified by the
361: .Fl m
362: option and print an OpenSSH compatible private
1.37 markus 363: (or public) key to stdout.
1.122 jmc 364: This option allows importing keys from other software, including several
365: commercial SSH implementations.
366: The default import format is
367: .Dq RFC4716 .
1.188 jmc 368: .It Fl K
1.187 djm 369: Download resident keys from a FIDO authenticator.
370: Public and private key files will be written to the current directory for
371: each downloaded key.
1.111 djm 372: .It Fl k
373: Generate a KRL file.
374: In this mode,
375: .Nm
376: will generate a KRL file at the location specified via the
377: .Fl f
1.114 jmc 378: flag that revokes every key or certificate presented on the command line.
1.111 djm 379: Keys/certificates to be revoked may be specified by public key file or
380: using the format described in the
381: .Sx KEY REVOCATION LISTS
382: section.
1.86 djm 383: .It Fl L
1.129 djm 384: Prints the contents of one or more certificates.
1.9 markus 385: .It Fl l
1.77 grunk 386: Show fingerprint of specified public key file.
1.50 markus 387: For RSA and DSA keys
388: .Nm
1.78 jmc 389: tries to find the matching public key file and prints its fingerprint.
390: If combined with
391: .Fl v ,
1.132 jmc 392: a visual ASCII art representation of the key is supplied with the
1.131 djm 393: fingerprint.
1.184 djm 394: .It Fl M Cm generate
395: Generate candidate Diffie-Hellman Group Exchange (DH-GEX) parameters for
396: eventual use by the
397: .Sq diffie-hellman-group-exchange-*
398: key exchange methods.
399: The numbers generated by this operation must be further screened before
400: use.
401: See the
402: .Sx MODULI GENERATION
403: section for more information.
404: .It Fl M Cm screen
405: Screen candidate parameters for Diffie-Hellman Group Exchange.
406: This will accept a list of candidate numbers and test that they are
407: safe (Sophie Germain) primes with acceptable group generators.
408: The results of this operation may be added to the
409: .Pa /etc/moduli
410: file.
411: See the
412: .Sx MODULI GENERATION
413: section for more information.
1.95 djm 414: .It Fl m Ar key_format
1.155 djm 415: Specify a key format for key generation, the
1.95 djm 416: .Fl i
1.155 djm 417: (import),
1.95 djm 418: .Fl e
1.155 djm 419: (export) conversion options, and the
420: .Fl p
421: change passphrase operation.
422: The latter may be used to convert between OpenSSH private key and PEM
423: private key formats.
1.95 djm 424: The supported key formats are:
425: .Dq RFC4716
1.96 jmc 426: (RFC 4716/SSH2 public or private key),
1.95 djm 427: .Dq PKCS8
1.161 djm 428: (PKCS8 public or private key)
1.95 djm 429: or
430: .Dq PEM
431: (PEM public key).
1.161 djm 432: By default OpenSSH will write newly-generated private keys in its own
433: format, but when converting public keys for export the default format is
1.95 djm 434: .Dq RFC4716 .
1.148 djm 435: Setting a format of
436: .Dq PEM
437: when generating or updating a supported private key type will cause the
438: key to be stored in the legacy PEM private key format.
1.66 jmc 439: .It Fl N Ar new_passphrase
440: Provides the new passphrase.
1.84 djm 441: .It Fl n Ar principals
442: Specify one or more principals (user or host names) to be included in
443: a certificate when signing a key.
444: Multiple principals may be specified, separated by commas.
445: Please see the
446: .Sx CERTIFICATES
447: section for details.
1.93 djm 448: .It Fl O Ar option
1.184 djm 449: Specify a key/value option.
450: These are specific to the operation that
451: .Nm
452: has been requested to perform.
453: .Pp
454: When signing certificates, one of the options listed in the
1.183 djm 455: .Sx CERTIFICATES
1.184 djm 456: section may be specified here.
457: .Pp
458: When performing moduli generation or screening, one of the options
459: listed in the
460: .Sx MODULI GENERATION
461: section may be specified.
462: .Pp
1.190 jmc 463: When generating a key that will be hosted on a FIDO authenticator,
464: this flag may be used to specify key-specific options.
465: Those supported at present are:
466: .Bl -tag -width Ds
467: .It Cm application
468: Override the default FIDO application/origin string of
1.189 djm 469: .Dq ssh: .
1.190 jmc 470: This may be useful when generating host or domain-specific resident keys.
471: .It Cm device
472: Explicitly specify a
1.189 djm 473: .Xr fido 4
474: device to use, rather than letting the token middleware select one.
1.190 jmc 475: .It Cm no-touch-required
476: Indicate that the generated private key should not require touch
1.185 djm 477: events (user presence) when making signatures.
478: Note that
479: .Xr sshd 8
480: will refuse such signatures by default, unless overridden via
481: an authorized_keys option.
1.190 jmc 482: .It Cm resident
483: Indicate that the key should be stored on the FIDO authenticator itself.
1.185 djm 484: Resident keys may be supported on FIDO2 tokens and typically require that
485: a PIN be set on the token prior to generation.
486: Resident keys may be loaded off the token using
487: .Xr ssh-add 1 .
1.190 jmc 488: .It Cm user
489: A username to be associated with a resident key,
1.189 djm 490: overriding the empty default username.
491: Specifying a username may be useful when generating multiple resident keys
492: for the same application name.
1.190 jmc 493: .El
1.185 djm 494: .Pp
495: The
496: .Fl O
497: option may be specified multiple times.
1.66 jmc 498: .It Fl P Ar passphrase
499: Provides the (old) passphrase.
1.2 deraadt 500: .It Fl p
1.1 deraadt 501: Requests changing the passphrase of a private key file instead of
1.12 aaron 502: creating a new private key.
503: The program will prompt for the file
1.1 deraadt 504: containing the private key, for the old passphrase, and twice for the
505: new passphrase.
1.113 jmc 506: .It Fl Q
507: Test whether keys have been revoked in a KRL.
1.5 aaron 508: .It Fl q
509: Silence
510: .Nm ssh-keygen .
1.152 djm 511: .It Fl R Ar hostname | [hostname]:port
1.151 djm 512: Removes all keys belonging to the specified
1.64 djm 513: .Ar hostname
1.151 djm 514: (with optional port number)
1.65 jmc 515: from a
1.64 djm 516: .Pa known_hosts
517: file.
1.65 jmc 518: This option is useful to delete hashed hosts (see the
1.64 djm 519: .Fl H
520: option above).
1.66 jmc 521: .It Fl r Ar hostname
522: Print the SSHFP fingerprint resource record named
523: .Ar hostname
524: for the specified public key file.
1.84 djm 525: .It Fl s Ar ca_key
526: Certify (sign) a public key using the specified CA key.
527: Please see the
528: .Sx CERTIFICATES
529: section for details.
1.111 djm 530: .Pp
531: When generating a KRL,
532: .Fl s
1.112 jmc 533: specifies a path to a CA public key file used to revoke certificates directly
1.111 djm 534: by key ID or serial number.
535: See the
536: .Sx KEY REVOCATION LISTS
537: section for details.
1.175 djm 538: .It Fl t Cm dsa | ecdsa | ecdsa-sk | ed25519 | ed25519-sk | rsa
1.66 jmc 539: Specifies the type of key to create.
540: The possible values are
1.100 naddy 541: .Dq dsa ,
1.118 naddy 542: .Dq ecdsa ,
1.173 naddy 543: .Dq ecdsa-sk ,
1.118 naddy 544: .Dq ed25519 ,
1.175 djm 545: .Dq ed25519-sk ,
1.100 naddy 546: or
1.139 jmc 547: .Dq rsa .
1.159 djm 548: .Pp
549: This flag may also be used to specify the desired signature type when
1.160 jmc 550: signing certificates using an RSA CA key.
1.159 djm 551: The available RSA signature variants are
552: .Dq ssh-rsa
553: (SHA1 signatures, not recommended),
1.160 jmc 554: .Dq rsa-sha2-256 ,
555: and
1.159 djm 556: .Dq rsa-sha2-512
557: (the default).
1.142 djm 558: .It Fl U
559: When used in combination with
560: .Fl s ,
561: this option indicates that a CA key resides in a
562: .Xr ssh-agent 1 .
563: See the
564: .Sx CERTIFICATES
565: section for more information.
1.112 jmc 566: .It Fl u
567: Update a KRL.
568: When specified with
569: .Fl k ,
1.114 jmc 570: keys listed via the command line are added to the existing KRL rather than
1.112 jmc 571: a new KRL being created.
1.84 djm 572: .It Fl V Ar validity_interval
573: Specify a validity interval when signing a certificate.
574: A validity interval may consist of a single time, indicating that the
575: certificate is valid beginning now and expiring at that time, or may consist
576: of two times separated by a colon to indicate an explicit time interval.
1.145 djm 577: .Pp
578: The start time may be specified as the string
579: .Dq always
580: to indicate the certificate has no specified start time,
1.147 djm 581: a date in YYYYMMDD format, a time in YYYYMMDDHHMM[SS] format,
1.145 djm 582: a relative time (to the current time) consisting of a minus sign followed by
583: an interval in the format described in the
1.116 jmc 584: TIME FORMATS section of
1.90 jmc 585: .Xr sshd_config 5 .
1.145 djm 586: .Pp
1.147 djm 587: The end time may be specified as a YYYYMMDD date, a YYYYMMDDHHMM[SS] time,
1.145 djm 588: a relative time starting with a plus character or the string
589: .Dq forever
590: to indicate that the certificate has no expirty date.
1.84 djm 591: .Pp
592: For example:
593: .Dq +52w1d
594: (valid from now to 52 weeks and one day from now),
595: .Dq -4w:+4w
596: (valid from four weeks ago to four weeks from now),
597: .Dq 20100101123000:20110101123000
598: (valid from 12:30 PM, January 1st, 2010 to 12:30 PM, January 1st, 2011),
599: .Dq -1d:20110101
600: (valid from yesterday to midnight, January 1st, 2011).
1.145 djm 601: .Dq -1m:forever
602: (valid from one minute ago and never expiring).
1.61 djm 603: .It Fl v
604: Verbose mode.
605: Causes
606: .Nm
607: to print debugging messages about its progress.
608: This is helpful for debugging moduli generation.
609: Multiple
610: .Fl v
611: options increase the verbosity.
612: The maximum is 3.
1.173 naddy 613: .It Fl w Ar provider
1.180 naddy 614: Specifies a path to a library that will be used when creating
615: FIDO authenticator-hosted keys, overriding the default of using
616: the internal USB HID support.
1.182 jmc 617: .It Fl Y Cm check-novalidate
618: Checks that a signature generated using
619: .Nm
620: .Fl Y Cm sign
621: has a valid structure.
622: This does not validate if a signature comes from an authorized signer.
623: When testing a signature,
624: .Nm
625: accepts a message on standard input and a signature namespace using
626: .Fl n .
627: A file containing the corresponding signature must also be supplied using the
628: .Fl s
629: flag.
630: Successful testing of the signature is signalled by
631: .Nm
632: returning a zero exit status.
1.166 jmc 633: .It Fl Y Cm sign
1.163 djm 634: Cryptographically sign a file or some data using a SSH key.
635: When signing,
636: .Nm
637: accepts zero or more files to sign on the command-line - if no files
638: are specified then
639: .Nm
640: will sign data presented on standard input.
641: Signatures are written to the path of the input file with
642: .Dq .sig
643: appended, or to standard output if the message to be signed was read from
644: standard input.
645: .Pp
646: The key used for signing is specified using the
647: .Fl f
648: option and may refer to either a private key, or a public key with the private
649: half available via
650: .Xr ssh-agent 1 .
651: An additional signature namespace, used to prevent signature confusion across
652: different domains of use (e.g. file signing vs email signing) must be provided
653: via the
654: .Fl n
655: flag.
656: Namespaces are arbitrary strings, and may include:
657: .Dq file
658: for file signing,
659: .Dq email
660: for email signing.
661: For custom uses, it is recommended to use names following a
662: NAMESPACE@YOUR.DOMAIN pattern to generate unambiguous namespaces.
1.166 jmc 663: .It Fl Y Cm verify
1.163 djm 664: Request to verify a signature generated using
665: .Nm
1.166 jmc 666: .Fl Y Cm sign
1.163 djm 667: as described above.
668: When verifying a signature,
669: .Nm
670: accepts a message on standard input and a signature namespace using
671: .Fl n .
672: A file containing the corresponding signature must also be supplied using the
673: .Fl s
674: flag, along with the identity of the signer using
675: .Fl I
676: and a list of allowed signers via the
677: .Fl f
678: flag.
679: The format of the allowed signers file is documented in the
680: .Sx ALLOWED SIGNERS
681: section below.
682: A file containing revoked keys can be passed using the
683: .Fl r
1.165 jmc 684: flag.
685: The revocation file may be a KRL or a one-per-line list of public keys.
1.163 djm 686: Successful verification by an authorized signer is signalled by
687: .Nm
688: returning a zero exit status.
1.181 jmc 689: .It Fl y
690: This option will read a private
691: OpenSSH format file and print an OpenSSH public key to stdout.
1.93 djm 692: .It Fl z Ar serial_number
693: Specifies a serial number to be embedded in the certificate to distinguish
694: this certificate from others from the same CA.
1.156 djm 695: If the
696: .Ar serial_number
697: is prefixed with a
698: .Sq +
699: character, then the serial number will be incremented for each certificate
700: signed on a single command-line.
1.93 djm 701: The default serial number is zero.
1.111 djm 702: .Pp
703: When generating a KRL, the
704: .Fl z
705: flag is used to specify a KRL version number.
1.2 deraadt 706: .El
1.60 djm 707: .Sh MODULI GENERATION
708: .Nm
709: may be used to generate groups for the Diffie-Hellman Group Exchange
710: (DH-GEX) protocol.
711: Generating these groups is a two-step process: first, candidate
712: primes are generated using a fast, but memory intensive process.
713: These candidate primes are then tested for suitability (a CPU-intensive
714: process).
715: .Pp
716: Generation of primes is performed using the
1.184 djm 717: .Fl M Cm generate
1.60 djm 718: option.
719: The desired length of the primes may be specified by the
1.184 djm 720: .Fl O Cm bits
1.60 djm 721: option.
722: For example:
723: .Pp
1.184 djm 724: .Dl # ssh-keygen -M generate -O bits=2048 moduli-2048.candidates
1.60 djm 725: .Pp
726: By default, the search for primes begins at a random point in the
727: desired length range.
728: This may be overridden using the
1.184 djm 729: .Fl O Cm start
1.60 djm 730: option, which specifies a different start point (in hex).
731: .Pp
1.109 dtucker 732: Once a set of candidates have been generated, they must be screened for
1.60 djm 733: suitability.
734: This may be performed using the
1.184 djm 735: .Fl M Cm screen
1.60 djm 736: option.
737: In this mode
738: .Nm
739: will read candidates from standard input (or a file specified using the
740: .Fl f
741: option).
742: For example:
743: .Pp
1.184 djm 744: .Dl # ssh-keygen -M screen -f moduli-2048.candidates moduli-2048
1.60 djm 745: .Pp
746: By default, each candidate will be subjected to 100 primality tests.
747: This may be overridden using the
1.184 djm 748: .Fl O Cm prime-tests
1.60 djm 749: option.
750: The DH generator value will be chosen automatically for the
751: prime under consideration.
752: If a specific generator is desired, it may be requested using the
1.184 djm 753: .Fl O Cm generator
1.60 djm 754: option.
1.66 jmc 755: Valid generator values are 2, 3, and 5.
1.60 djm 756: .Pp
757: Screened DH groups may be installed in
758: .Pa /etc/moduli .
759: It is important that this file contains moduli of a range of bit lengths and
760: that both ends of a connection share common moduli.
1.184 djm 761: .Pp
762: A number of options are available for moduli generation and screening via the
763: .Fl O
764: flag:
1.186 jmc 765: .Bl -tag -width Ds
1.184 djm 766: .It Ic lines Ns = Ns Ar number
767: Exit after screening the specified number of lines while performing DH
768: candidate screening.
769: .It Ic start-line Ns = Ns Ar line-number
770: Start screening at the specified line number while performing DH candidate
771: screening.
772: .It Ic checkpoint Ns = Ns Ar filename
773: Write the last line processed to the specified file while performing DH
774: candidate screening.
775: This will be used to skip lines in the input file that have already been
776: processed if the job is restarted.
777: .It Ic memory Ns = Ns Ar mbytes
778: Specify the amount of memory to use (in megabytes) when generating
779: candidate moduli for DH-GEX.
780: .It Ic start Ns = Ns Ar hex-value
781: Specify start point (in hex) when generating candidate moduli for DH-GEX.
782: .It Ic generator Ns = Ns Ar value
783: Specify desired generator (in decimal) when testing candidate moduli for DH-GEX.
784: .El
1.84 djm 785: .Sh CERTIFICATES
786: .Nm
787: supports signing of keys to produce certificates that may be used for
788: user or host authentication.
789: Certificates consist of a public key, some identity information, zero or
1.94 jmc 790: more principal (user or host) names and a set of options that
1.84 djm 791: are signed by a Certification Authority (CA) key.
792: Clients or servers may then trust only the CA key and verify its signature
793: on a certificate rather than trusting many user/host keys.
794: Note that OpenSSH certificates are a different, and much simpler, format to
795: the X.509 certificates used in
796: .Xr ssl 8 .
797: .Pp
798: .Nm
799: supports two types of certificates: user and host.
800: User certificates authenticate users to servers, whereas host certificates
1.85 jmc 801: authenticate server hosts to users.
802: To generate a user certificate:
1.84 djm 803: .Pp
804: .Dl $ ssh-keygen -s /path/to/ca_key -I key_id /path/to/user_key.pub
805: .Pp
806: The resultant certificate will be placed in
1.91 djm 807: .Pa /path/to/user_key-cert.pub .
1.84 djm 808: A host certificate requires the
809: .Fl h
810: option:
811: .Pp
812: .Dl $ ssh-keygen -s /path/to/ca_key -I key_id -h /path/to/host_key.pub
813: .Pp
814: The host certificate will be output to
1.91 djm 815: .Pa /path/to/host_key-cert.pub .
1.98 djm 816: .Pp
817: It is possible to sign using a CA key stored in a PKCS#11 token by
818: providing the token library using
819: .Fl D
820: and identifying the CA key by providing its public half as an argument
821: to
822: .Fl s :
823: .Pp
1.127 naddy 824: .Dl $ ssh-keygen -s ca_key.pub -D libpkcs11.so -I key_id user_key.pub
1.142 djm 825: .Pp
826: Similarly, it is possible for the CA key to be hosted in a
827: .Xr ssh-agent 1 .
828: This is indicated by the
829: .Fl U
830: flag and, again, the CA key must be identified by its public half.
831: .Pp
832: .Dl $ ssh-keygen -Us ca_key.pub -I key_id user_key.pub
1.98 djm 833: .Pp
834: In all cases,
1.84 djm 835: .Ar key_id
836: is a "key identifier" that is logged by the server when the certificate
837: is used for authentication.
838: .Pp
839: Certificates may be limited to be valid for a set of principal (user/host)
840: names.
841: By default, generated certificates are valid for all users or hosts.
842: To generate a certificate for a specified set of principals:
843: .Pp
844: .Dl $ ssh-keygen -s ca_key -I key_id -n user1,user2 user_key.pub
1.127 naddy 845: .Dl "$ ssh-keygen -s ca_key -I key_id -h -n host.domain host_key.pub"
1.84 djm 846: .Pp
847: Additional limitations on the validity and use of user certificates may
1.94 jmc 848: be specified through certificate options.
1.93 djm 849: A certificate option may disable features of the SSH session, may be
1.84 djm 850: valid only when presented from particular source addresses or may
851: force the use of a specific command.
1.183 djm 852: .Pp
853: The options that are valid for user certificates are:
854: .Pp
855: .Bl -tag -width Ds -compact
856: .It Ic clear
857: Clear all enabled permissions.
858: This is useful for clearing the default set of permissions so permissions may
859: be added individually.
860: .Pp
861: .It Ic critical : Ns Ar name Ns Op Ns = Ns Ar contents
862: .It Ic extension : Ns Ar name Ns Op Ns = Ns Ar contents
863: Includes an arbitrary certificate critical option or extension.
864: The specified
865: .Ar name
866: should include a domain suffix, e.g.\&
867: .Dq name@example.com .
868: If
869: .Ar contents
870: is specified then it is included as the contents of the extension/option
871: encoded as a string, otherwise the extension/option is created with no
872: contents (usually indicating a flag).
873: Extensions may be ignored by a client or server that does not recognise them,
874: whereas unknown critical options will cause the certificate to be refused.
875: .Pp
876: .It Ic force-command Ns = Ns Ar command
877: Forces the execution of
878: .Ar command
879: instead of any shell or command specified by the user when
880: the certificate is used for authentication.
881: .Pp
882: .It Ic no-agent-forwarding
883: Disable
884: .Xr ssh-agent 1
885: forwarding (permitted by default).
886: .Pp
887: .It Ic no-port-forwarding
888: Disable port forwarding (permitted by default).
889: .Pp
890: .It Ic no-pty
891: Disable PTY allocation (permitted by default).
892: .Pp
893: .It Ic no-user-rc
894: Disable execution of
895: .Pa ~/.ssh/rc
896: by
897: .Xr sshd 8
898: (permitted by default).
899: .Pp
900: .It Ic no-x11-forwarding
901: Disable X11 forwarding (permitted by default).
902: .Pp
903: .It Ic permit-agent-forwarding
904: Allows
905: .Xr ssh-agent 1
906: forwarding.
907: .Pp
908: .It Ic permit-port-forwarding
909: Allows port forwarding.
910: .Pp
911: .It Ic permit-pty
912: Allows PTY allocation.
913: .Pp
914: .It Ic permit-user-rc
915: Allows execution of
916: .Pa ~/.ssh/rc
917: by
918: .Xr sshd 8 .
919: .Pp
920: .It Ic permit-X11-forwarding
921: Allows X11 forwarding.
922: .Pp
923: .It Ic no-touch-required
924: Do not require signatures made using this key require demonstration
925: of user presence (e.g. by having the user touch the key).
1.192 ! naddy 926: This option only makes sense for the FIDO authenticator algorithms
1.183 djm 927: .Cm ecdsa-sk
928: and
929: .Cm ed25519-sk .
930: .Pp
931: .It Ic source-address Ns = Ns Ar address_list
932: Restrict the source addresses from which the certificate is considered valid.
933: The
934: .Ar address_list
935: is a comma-separated list of one or more address/netmask pairs in CIDR
936: format.
937: .El
938: .Pp
939: At present, no standard options are valid for host keys.
1.84 djm 940: .Pp
941: Finally, certificates may be defined with a validity lifetime.
942: The
943: .Fl V
944: option allows specification of certificate start and end times.
945: A certificate that is presented at a time outside this range will not be
946: considered valid.
1.110 jmc 947: By default, certificates are valid from
948: .Ux
949: Epoch to the distant future.
1.84 djm 950: .Pp
951: For certificates to be used for user or host authentication, the CA
952: public key must be trusted by
953: .Xr sshd 8
954: or
955: .Xr ssh 1 .
956: Please refer to those manual pages for details.
1.111 djm 957: .Sh KEY REVOCATION LISTS
958: .Nm
959: is able to manage OpenSSH format Key Revocation Lists (KRLs).
960: These binary files specify keys or certificates to be revoked using a
1.119 tedu 961: compact format, taking as little as one bit per certificate if they are being
1.111 djm 962: revoked by serial number.
963: .Pp
964: KRLs may be generated using the
965: .Fl k
966: flag.
1.114 jmc 967: This option reads one or more files from the command line and generates a new
1.111 djm 968: KRL.
969: The files may either contain a KRL specification (see below) or public keys,
970: listed one per line.
971: Plain public keys are revoked by listing their hash or contents in the KRL and
972: certificates revoked by serial number or key ID (if the serial is zero or
973: not available).
974: .Pp
975: Revoking keys using a KRL specification offers explicit control over the
976: types of record used to revoke keys and may be used to directly revoke
977: certificates by serial number or key ID without having the complete original
978: certificate on hand.
979: A KRL specification consists of lines containing one of the following directives
980: followed by a colon and some directive-specific information.
981: .Bl -tag -width Ds
1.115 jmc 982: .It Cm serial : Ar serial_number Ns Op - Ns Ar serial_number
1.111 djm 983: Revokes a certificate with the specified serial number.
1.112 jmc 984: Serial numbers are 64-bit values, not including zero and may be expressed
1.111 djm 985: in decimal, hex or octal.
986: If two serial numbers are specified separated by a hyphen, then the range
987: of serial numbers including and between each is revoked.
988: The CA key must have been specified on the
989: .Nm
1.114 jmc 990: command line using the
1.111 djm 991: .Fl s
992: option.
993: .It Cm id : Ar key_id
994: Revokes a certificate with the specified key ID string.
995: The CA key must have been specified on the
996: .Nm
1.114 jmc 997: command line using the
1.111 djm 998: .Fl s
999: option.
1000: .It Cm key : Ar public_key
1001: Revokes the specified key.
1.112 jmc 1002: If a certificate is listed, then it is revoked as a plain public key.
1.111 djm 1003: .It Cm sha1 : Ar public_key
1.149 djm 1004: Revokes the specified key by including its SHA1 hash in the KRL.
1005: .It Cm sha256 : Ar public_key
1006: Revokes the specified key by including its SHA256 hash in the KRL.
1007: KRLs that revoke keys by SHA256 hash are not supported by OpenSSH versions
1008: prior to 7.9.
1009: .It Cm hash : Ar fingerprint
1.150 djm 1010: Revokes a key using a fingerprint hash, as obtained from a
1.149 djm 1011: .Xr sshd 8
1012: authentication log message or the
1013: .Nm
1014: .Fl l
1015: flag.
1016: Only SHA256 fingerprints are supported here and resultant KRLs are
1017: not supported by OpenSSH versions prior to 7.9.
1.111 djm 1018: .El
1019: .Pp
1020: KRLs may be updated using the
1021: .Fl u
1022: flag in addition to
1023: .Fl k .
1.114 jmc 1024: When this option is specified, keys listed via the command line are merged into
1.111 djm 1025: the KRL, adding to those already there.
1026: .Pp
1027: It is also possible, given a KRL, to test whether it revokes a particular key
1028: (or keys).
1029: The
1030: .Fl Q
1.128 jmc 1031: flag will query an existing KRL, testing each key specified on the command line.
1.114 jmc 1032: If any key listed on the command line has been revoked (or an error encountered)
1.111 djm 1033: then
1034: .Nm
1035: will exit with a non-zero exit status.
1036: A zero exit status will only be returned if no key was revoked.
1.163 djm 1037: .Sh ALLOWED SIGNERS
1038: When verifying signatures,
1039: .Nm
1040: uses a simple list of identities and keys to determine whether a signature
1041: comes from an authorized source.
1042: This "allowed signers" file uses a format patterned after the
1043: AUTHORIZED_KEYS FILE FORMAT described in
1.165 jmc 1044: .Xr sshd 8 .
1.163 djm 1045: Each line of the file contains the following space-separated fields:
1046: principals, options, keytype, base64-encoded key.
1047: Empty lines and lines starting with a
1048: .Ql #
1049: are ignored as comments.
1050: .Pp
1051: The principals field is a pattern-list (See PATTERNS in
1052: .Xr ssh_config 5 )
1053: consisting of one or more comma-separated USER@DOMAIN identity patterns
1054: that are accepted for signing.
1055: When verifying, the identity presented via the
1.172 jmc 1056: .Fl I
1057: option must match a principals pattern in order for the corresponding key to be
1.163 djm 1058: considered acceptable for verification.
1059: .Pp
1060: The options (if present) consist of comma-separated option specifications.
1061: No spaces are permitted, except within double quotes.
1062: The following option specifications are supported (note that option keywords
1063: are case-insensitive):
1064: .Bl -tag -width Ds
1065: .It Cm cert-authority
1066: Indicates that this key is accepted as a certificate authority (CA) and
1067: that certificates signed by this CA may be accepted for verification.
1068: .It Cm namespaces="namespace-list"
1069: Specifies a pattern-list of namespaces that are accepted for this key.
1.164 djm 1070: If this option is present, the signature namespace embedded in the
1.163 djm 1071: signature object and presented on the verification command-line must
1072: match the specified list before the key will be considered acceptable.
1073: .El
1074: .Pp
1075: When verifying signatures made by certificates, the expected principal
1076: name must match both the principals pattern in the allowed signers file and
1077: the principals embedded in the certificate itself.
1078: .Pp
1079: An example allowed signers file:
1080: .Bd -literal -offset 3n
1081: # Comments allowed at start of line
1082: user1@example.com,user2@example.com ssh-rsa AAAAX1...
1083: # A certificate authority, trusted for all principals in a domain.
1084: *@example.com cert-authority ssh-ed25519 AAAB4...
1085: # A key that is accepted only for file signing.
1086: user2@example.com namespaces="file" ssh-ed25519 AAA41...
1087: .Ed
1.173 naddy 1088: .Sh ENVIRONMENT
1089: .Bl -tag -width Ds
1090: .It Ev SSH_SK_PROVIDER
1.180 naddy 1091: Specifies the path to a library used to interact with FIDO authenticators.
1.173 naddy 1092: .El
1.2 deraadt 1093: .Sh FILES
1.100 naddy 1094: .Bl -tag -width Ds -compact
1.68 djm 1095: .It Pa ~/.ssh/id_dsa
1.100 naddy 1096: .It Pa ~/.ssh/id_ecdsa
1.173 naddy 1097: .It Pa ~/.ssh/id_ecdsa_sk
1.118 naddy 1098: .It Pa ~/.ssh/id_ed25519
1.176 naddy 1099: .It Pa ~/.ssh/id_ed25519_sk
1.100 naddy 1100: .It Pa ~/.ssh/id_rsa
1.180 naddy 1101: Contains the DSA, ECDSA, authenticator-hosted ECDSA, Ed25519,
1102: authenticator-hosted Ed25519 or RSA authentication identity of the user.
1.15 deraadt 1103: This file should not be readable by anyone but the user.
1104: It is possible to
1105: specify a passphrase when generating the key; that passphrase will be
1.80 dtucker 1106: used to encrypt the private part of this file using 128-bit AES.
1.15 deraadt 1107: This file is not automatically accessed by
1108: .Nm
1109: but it is offered as the default file for the private key.
1.46 markus 1110: .Xr ssh 1
1.15 deraadt 1111: will read this file when a login attempt is made.
1.100 naddy 1112: .Pp
1.68 djm 1113: .It Pa ~/.ssh/id_dsa.pub
1.100 naddy 1114: .It Pa ~/.ssh/id_ecdsa.pub
1.173 naddy 1115: .It Pa ~/.ssh/id_ecdsa_sk.pub
1.118 naddy 1116: .It Pa ~/.ssh/id_ed25519.pub
1.176 naddy 1117: .It Pa ~/.ssh/id_ed25519_sk.pub
1.68 djm 1118: .It Pa ~/.ssh/id_rsa.pub
1.180 naddy 1119: Contains the DSA, ECDSA, authenticator-hosted ECDSA, Ed25519,
1120: authenticator-hosted Ed25519 or RSA public key for authentication.
1.15 deraadt 1121: The contents of this file should be added to
1.68 djm 1122: .Pa ~/.ssh/authorized_keys
1.15 deraadt 1123: on all machines
1.49 deraadt 1124: where the user wishes to log in using public key authentication.
1.12 aaron 1125: There is no need to keep the contents of this file secret.
1.100 naddy 1126: .Pp
1.60 djm 1127: .It Pa /etc/moduli
1128: Contains Diffie-Hellman groups used for DH-GEX.
1129: The file format is described in
1130: .Xr moduli 5 .
1.19 aaron 1131: .El
1.2 deraadt 1132: .Sh SEE ALSO
1133: .Xr ssh 1 ,
1134: .Xr ssh-add 1 ,
1.8 ericj 1135: .Xr ssh-agent 1 ,
1.60 djm 1136: .Xr moduli 5 ,
1.30 itojun 1137: .Xr sshd 8
1.37 markus 1138: .Rs
1.73 markus 1139: .%R RFC 4716
1140: .%T "The Secure Shell (SSH) Public Key File Format"
1141: .%D 2006
1.37 markus 1142: .Re
1.59 jmc 1143: .Sh AUTHORS
1144: OpenSSH is a derivative of the original and free
1145: ssh 1.2.12 release by Tatu Ylonen.
1146: Aaron Campbell, Bob Beck, Markus Friedl, Niels Provos,
1147: Theo de Raadt and Dug Song
1148: removed many bugs, re-added newer features and
1149: created OpenSSH.
1150: Markus Friedl contributed the support for SSH
1151: protocol versions 1.5 and 2.0.
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