Annotation of src/usr.bin/ssh/ssh-keygen.1, Revision 1.195
1.195 ! jmc 1: .\" $OpenBSD: ssh-keygen.1,v 1.194 2020/01/23 02:43:48 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: .\"
1.195 ! jmc 38: .Dd $Mdocdate: January 23 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
1.194 djm 141: .Fl Y Cm find-principal
142: .Fl s Ar signature_file
143: .Fl f Ar allowed_signers_file
144: .Nm ssh-keygen
1.171 jmc 145: .Fl Y Cm check-novalidate
146: .Fl n Ar namespace
147: .Fl s Ar signature_file
148: .Nm ssh-keygen
1.163 djm 149: .Fl Y Cm sign
150: .Fl f Ar key_file
151: .Fl n Ar namespace
152: .Ar
153: .Nm ssh-keygen
154: .Fl Y Cm verify
1.171 jmc 155: .Fl f Ar allowed_signers_file
1.163 djm 156: .Fl I Ar signer_identity
157: .Fl n Ar namespace
158: .Fl s Ar signature_file
159: .Op Fl r Ar revocation_file
1.13 aaron 160: .Sh DESCRIPTION
1.2 deraadt 161: .Nm
1.37 markus 162: generates, manages and converts authentication keys for
1.2 deraadt 163: .Xr ssh 1 .
1.15 deraadt 164: .Nm
1.140 jmc 165: can create keys for use by SSH protocol version 2.
1.130 jmc 166: .Pp
1.58 jmc 167: The type of key to be generated is specified with the
1.25 markus 168: .Fl t
1.52 djm 169: option.
1.70 djm 170: If invoked without any arguments,
171: .Nm
1.141 naddy 172: will generate an RSA key.
1.15 deraadt 173: .Pp
1.60 djm 174: .Nm
175: is also used to generate groups for use in Diffie-Hellman group
176: exchange (DH-GEX).
177: See the
178: .Sx MODULI GENERATION
179: section for details.
180: .Pp
1.111 djm 181: Finally,
182: .Nm
183: can be used to generate and update Key Revocation Lists, and to test whether
1.112 jmc 184: given keys have been revoked by one.
185: See the
1.111 djm 186: .Sx KEY REVOCATION LISTS
187: section for details.
188: .Pp
1.2 deraadt 189: Normally each user wishing to use SSH
1.99 djm 190: with public key authentication runs this once to create the authentication
1.1 deraadt 191: key in
1.118 naddy 192: .Pa ~/.ssh/id_dsa ,
1.99 djm 193: .Pa ~/.ssh/id_ecdsa ,
1.173 naddy 194: .Pa ~/.ssh/id_ecdsa_sk ,
1.176 naddy 195: .Pa ~/.ssh/id_ed25519 ,
196: .Pa ~/.ssh/id_ed25519_sk
1.15 deraadt 197: or
1.68 djm 198: .Pa ~/.ssh/id_rsa .
1.15 deraadt 199: Additionally, the system administrator may use this to generate host keys,
200: as seen in
201: .Pa /etc/rc .
1.2 deraadt 202: .Pp
1.1 deraadt 203: Normally this program generates the key and asks for a file in which
1.12 aaron 204: to store the private key.
205: The public key is stored in a file with the same name but
1.2 deraadt 206: .Dq .pub
1.12 aaron 207: appended.
208: The program also asks for a passphrase.
209: The passphrase may be empty to indicate no passphrase
1.26 markus 210: (host keys must have an empty passphrase), or it may be a string of
1.12 aaron 211: arbitrary length.
1.51 stevesk 212: A passphrase is similar to a password, except it can be a phrase with a
213: series of words, punctuation, numbers, whitespace, or any string of
214: characters you want.
215: Good passphrases are 10-30 characters long, are
1.1 deraadt 216: not simple sentences or otherwise easily guessable (English
1.42 markus 217: prose has only 1-2 bits of entropy per character, and provides very bad
1.51 stevesk 218: passphrases), and contain a mix of upper and lowercase letters,
219: numbers, and non-alphanumeric characters.
1.12 aaron 220: The passphrase can be changed later by using the
1.2 deraadt 221: .Fl p
1.1 deraadt 222: option.
1.2 deraadt 223: .Pp
1.12 aaron 224: There is no way to recover a lost passphrase.
1.105 djm 225: If the passphrase is lost or forgotten, a new key must be generated
226: and the corresponding public key copied to other machines.
1.2 deraadt 227: .Pp
1.153 djm 228: .Nm
229: will by default write keys in an OpenSSH-specific format.
230: This format is preferred as it offers better protection for
231: keys at rest as well as allowing storage of key comments within
232: the private key file itself.
233: The key comment may be useful to help identify the key.
1.12 aaron 234: The comment is initialized to
1.2 deraadt 235: .Dq user@host
236: when the key is created, but can be changed using the
237: .Fl c
1.1 deraadt 238: option.
1.153 djm 239: .Pp
240: It is still possible for
241: .Nm
242: to write the previously-used PEM format private keys using the
243: .Fl m
244: flag.
245: This may be used when generating new keys, and existing new-format
246: keys may be converted using this option in conjunction with the
247: .Fl p
248: (change passphrase) flag.
1.2 deraadt 249: .Pp
1.15 deraadt 250: After a key is generated, instructions below detail where the keys
251: should be placed to be activated.
252: .Pp
1.2 deraadt 253: The options are as follows:
254: .Bl -tag -width Ds
1.102 stevesk 255: .It Fl A
1.175 djm 256: For each of the key types (rsa, dsa, ecdsa and ed25519)
1.118 naddy 257: for which host keys
1.102 stevesk 258: do not exist, generate the host keys with the default key file path,
259: an empty passphrase, default bits for the key type, and default comment.
1.144 jmc 260: If
1.143 djm 261: .Fl f
1.144 jmc 262: has also been specified, its argument is used as a prefix to the
1.143 djm 263: default path for the resulting host key files.
1.104 jmc 264: This is used by
1.102 stevesk 265: .Pa /etc/rc
266: to generate new host keys.
1.117 djm 267: .It Fl a Ar rounds
1.169 jmc 268: When saving a private key, this option specifies the number of KDF
1.148 djm 269: (key derivation function) rounds used.
1.117 djm 270: Higher numbers result in slower passphrase verification and increased
271: resistance to brute-force password cracking (should the keys be stolen).
1.66 jmc 272: .It Fl B
273: Show the bubblebabble digest of specified private or public key file.
1.2 deraadt 274: .It Fl b Ar bits
1.12 aaron 275: Specifies the number of bits in the key to create.
1.158 dtucker 276: For RSA keys, the minimum size is 1024 bits and the default is 3072 bits.
277: Generally, 3072 bits is considered sufficient.
1.72 dtucker 278: DSA keys must be exactly 1024 bits as specified by FIPS 186-2.
1.106 djm 279: For ECDSA keys, the
280: .Fl b
1.107 deraadt 281: flag determines the key length by selecting from one of three elliptic
1.106 djm 282: curve sizes: 256, 384 or 521 bits.
283: Attempting to use bit lengths other than these three values for ECDSA keys
284: will fail.
1.176 naddy 285: ECDSA-SK, Ed25519 and Ed25519-SK keys have a fixed length and the
1.118 naddy 286: .Fl b
287: flag will be ignored.
1.66 jmc 288: .It Fl C Ar comment
289: Provides a new comment.
1.2 deraadt 290: .It Fl c
1.1 deraadt 291: Requests changing the comment in the private and public key files.
292: The program will prompt for the file containing the private keys, for
1.41 stevesk 293: the passphrase if the key has one, and for the new comment.
1.81 markus 294: .It Fl D Ar pkcs11
1.157 naddy 295: Download the public keys provided by the PKCS#11 shared library
1.83 markus 296: .Ar pkcs11 .
1.98 djm 297: When used in combination with
298: .Fl s ,
299: this option indicates that a CA key resides in a PKCS#11 token (see the
300: .Sx CERTIFICATES
301: section for details).
1.124 djm 302: .It Fl E Ar fingerprint_hash
303: Specifies the hash algorithm used when displaying key fingerprints.
304: Valid options are:
305: .Dq md5
306: and
307: .Dq sha256 .
308: The default is
309: .Dq sha256 .
1.37 markus 310: .It Fl e
1.40 markus 311: This option will read a private or public OpenSSH key file and
1.154 djm 312: print to stdout a public key in one of the formats specified by the
1.95 djm 313: .Fl m
314: option.
315: The default export format is
316: .Dq RFC4716 .
1.96 jmc 317: This option allows exporting OpenSSH keys for use by other programs, including
1.95 djm 318: several commercial SSH implementations.
1.151 djm 319: .It Fl F Ar hostname | [hostname]:port
1.66 jmc 320: Search for the specified
321: .Ar hostname
1.151 djm 322: (with optional port number)
1.66 jmc 323: in a
324: .Pa known_hosts
325: file, listing any occurrences found.
326: This option is useful to find hashed host names or addresses and may also be
327: used in conjunction with the
328: .Fl H
329: option to print found keys in a hashed format.
330: .It Fl f Ar filename
331: Specifies the filename of the key file.
1.57 jakob 332: .It Fl g
1.62 jakob 333: Use generic DNS format when printing fingerprint resource records using the
1.63 jmc 334: .Fl r
1.62 jakob 335: command.
1.66 jmc 336: .It Fl H
337: Hash a
338: .Pa known_hosts
1.67 dtucker 339: file.
340: This replaces all hostnames and addresses with hashed representations
341: within the specified file; the original content is moved to a file with
342: a .old suffix.
1.66 jmc 343: These hashes may be used normally by
344: .Nm ssh
345: and
346: .Nm sshd ,
347: but they do not reveal identifying information should the file's contents
348: be disclosed.
349: This option will not modify existing hashed hostnames and is therefore safe
350: to use on files that mix hashed and non-hashed names.
1.84 djm 351: .It Fl h
352: When signing a key, create a host certificate instead of a user
353: certificate.
354: Please see the
355: .Sx CERTIFICATES
356: section for details.
1.85 jmc 357: .It Fl I Ar certificate_identity
1.84 djm 358: Specify the key identity when signing a public key.
359: Please see the
360: .Sx CERTIFICATES
361: section for details.
1.37 markus 362: .It Fl i
363: This option will read an unencrypted private (or public) key file
1.95 djm 364: in the format specified by the
365: .Fl m
366: option and print an OpenSSH compatible private
1.37 markus 367: (or public) key to stdout.
1.122 jmc 368: This option allows importing keys from other software, including several
369: commercial SSH implementations.
370: The default import format is
371: .Dq RFC4716 .
1.188 jmc 372: .It Fl K
1.187 djm 373: Download resident keys from a FIDO authenticator.
374: Public and private key files will be written to the current directory for
375: each downloaded key.
1.111 djm 376: .It Fl k
377: Generate a KRL file.
378: In this mode,
379: .Nm
380: will generate a KRL file at the location specified via the
381: .Fl f
1.114 jmc 382: flag that revokes every key or certificate presented on the command line.
1.111 djm 383: Keys/certificates to be revoked may be specified by public key file or
384: using the format described in the
385: .Sx KEY REVOCATION LISTS
386: section.
1.86 djm 387: .It Fl L
1.129 djm 388: Prints the contents of one or more certificates.
1.9 markus 389: .It Fl l
1.77 grunk 390: Show fingerprint of specified public key file.
1.50 markus 391: For RSA and DSA keys
392: .Nm
1.78 jmc 393: tries to find the matching public key file and prints its fingerprint.
394: If combined with
395: .Fl v ,
1.132 jmc 396: a visual ASCII art representation of the key is supplied with the
1.131 djm 397: fingerprint.
1.184 djm 398: .It Fl M Cm generate
399: Generate candidate Diffie-Hellman Group Exchange (DH-GEX) parameters for
400: eventual use by the
401: .Sq diffie-hellman-group-exchange-*
402: key exchange methods.
403: The numbers generated by this operation must be further screened before
404: use.
405: See the
406: .Sx MODULI GENERATION
407: section for more information.
408: .It Fl M Cm screen
409: Screen candidate parameters for Diffie-Hellman Group Exchange.
410: This will accept a list of candidate numbers and test that they are
411: safe (Sophie Germain) primes with acceptable group generators.
412: The results of this operation may be added to the
413: .Pa /etc/moduli
414: file.
415: See the
416: .Sx MODULI GENERATION
417: section for more information.
1.95 djm 418: .It Fl m Ar key_format
1.155 djm 419: Specify a key format for key generation, the
1.95 djm 420: .Fl i
1.155 djm 421: (import),
1.95 djm 422: .Fl e
1.155 djm 423: (export) conversion options, and the
424: .Fl p
425: change passphrase operation.
426: The latter may be used to convert between OpenSSH private key and PEM
427: private key formats.
1.95 djm 428: The supported key formats are:
429: .Dq RFC4716
1.96 jmc 430: (RFC 4716/SSH2 public or private key),
1.95 djm 431: .Dq PKCS8
1.161 djm 432: (PKCS8 public or private key)
1.95 djm 433: or
434: .Dq PEM
435: (PEM public key).
1.161 djm 436: By default OpenSSH will write newly-generated private keys in its own
437: format, but when converting public keys for export the default format is
1.95 djm 438: .Dq RFC4716 .
1.148 djm 439: Setting a format of
440: .Dq PEM
441: when generating or updating a supported private key type will cause the
442: key to be stored in the legacy PEM private key format.
1.66 jmc 443: .It Fl N Ar new_passphrase
444: Provides the new passphrase.
1.84 djm 445: .It Fl n Ar principals
446: Specify one or more principals (user or host names) to be included in
447: a certificate when signing a key.
448: Multiple principals may be specified, separated by commas.
449: Please see the
450: .Sx CERTIFICATES
451: section for details.
1.93 djm 452: .It Fl O Ar option
1.184 djm 453: Specify a key/value option.
454: These are specific to the operation that
455: .Nm
456: has been requested to perform.
457: .Pp
458: When signing certificates, one of the options listed in the
1.183 djm 459: .Sx CERTIFICATES
1.184 djm 460: section may be specified here.
461: .Pp
462: When performing moduli generation or screening, one of the options
463: listed in the
464: .Sx MODULI GENERATION
465: section may be specified.
466: .Pp
1.190 jmc 467: When generating a key that will be hosted on a FIDO authenticator,
468: this flag may be used to specify key-specific options.
469: Those supported at present are:
470: .Bl -tag -width Ds
471: .It Cm application
472: Override the default FIDO application/origin string of
1.189 djm 473: .Dq ssh: .
1.190 jmc 474: This may be useful when generating host or domain-specific resident keys.
475: .It Cm device
476: Explicitly specify a
1.189 djm 477: .Xr fido 4
478: device to use, rather than letting the token middleware select one.
1.190 jmc 479: .It Cm no-touch-required
480: Indicate that the generated private key should not require touch
1.185 djm 481: events (user presence) when making signatures.
482: Note that
483: .Xr sshd 8
484: will refuse such signatures by default, unless overridden via
485: an authorized_keys option.
1.190 jmc 486: .It Cm resident
487: Indicate that the key should be stored on the FIDO authenticator itself.
1.185 djm 488: Resident keys may be supported on FIDO2 tokens and typically require that
489: a PIN be set on the token prior to generation.
490: Resident keys may be loaded off the token using
491: .Xr ssh-add 1 .
1.190 jmc 492: .It Cm user
493: A username to be associated with a resident key,
1.189 djm 494: overriding the empty default username.
495: Specifying a username may be useful when generating multiple resident keys
496: for the same application name.
1.190 jmc 497: .El
1.185 djm 498: .Pp
499: The
500: .Fl O
501: option may be specified multiple times.
1.66 jmc 502: .It Fl P Ar passphrase
503: Provides the (old) passphrase.
1.2 deraadt 504: .It Fl p
1.1 deraadt 505: Requests changing the passphrase of a private key file instead of
1.12 aaron 506: creating a new private key.
507: The program will prompt for the file
1.1 deraadt 508: containing the private key, for the old passphrase, and twice for the
509: new passphrase.
1.113 jmc 510: .It Fl Q
511: Test whether keys have been revoked in a KRL.
1.5 aaron 512: .It Fl q
513: Silence
514: .Nm ssh-keygen .
1.152 djm 515: .It Fl R Ar hostname | [hostname]:port
1.151 djm 516: Removes all keys belonging to the specified
1.64 djm 517: .Ar hostname
1.151 djm 518: (with optional port number)
1.65 jmc 519: from a
1.64 djm 520: .Pa known_hosts
521: file.
1.65 jmc 522: This option is useful to delete hashed hosts (see the
1.64 djm 523: .Fl H
524: option above).
1.66 jmc 525: .It Fl r Ar hostname
526: Print the SSHFP fingerprint resource record named
527: .Ar hostname
528: for the specified public key file.
1.84 djm 529: .It Fl s Ar ca_key
530: Certify (sign) a public key using the specified CA key.
531: Please see the
532: .Sx CERTIFICATES
533: section for details.
1.111 djm 534: .Pp
535: When generating a KRL,
536: .Fl s
1.112 jmc 537: specifies a path to a CA public key file used to revoke certificates directly
1.111 djm 538: by key ID or serial number.
539: See the
540: .Sx KEY REVOCATION LISTS
541: section for details.
1.175 djm 542: .It Fl t Cm dsa | ecdsa | ecdsa-sk | ed25519 | ed25519-sk | rsa
1.66 jmc 543: Specifies the type of key to create.
544: The possible values are
1.100 naddy 545: .Dq dsa ,
1.118 naddy 546: .Dq ecdsa ,
1.173 naddy 547: .Dq ecdsa-sk ,
1.118 naddy 548: .Dq ed25519 ,
1.175 djm 549: .Dq ed25519-sk ,
1.100 naddy 550: or
1.139 jmc 551: .Dq rsa .
1.159 djm 552: .Pp
553: This flag may also be used to specify the desired signature type when
1.160 jmc 554: signing certificates using an RSA CA key.
1.159 djm 555: The available RSA signature variants are
556: .Dq ssh-rsa
557: (SHA1 signatures, not recommended),
1.160 jmc 558: .Dq rsa-sha2-256 ,
559: and
1.159 djm 560: .Dq rsa-sha2-512
561: (the default).
1.142 djm 562: .It Fl U
563: When used in combination with
564: .Fl s ,
565: this option indicates that a CA key resides in a
566: .Xr ssh-agent 1 .
567: See the
568: .Sx CERTIFICATES
569: section for more information.
1.112 jmc 570: .It Fl u
571: Update a KRL.
572: When specified with
573: .Fl k ,
1.114 jmc 574: keys listed via the command line are added to the existing KRL rather than
1.112 jmc 575: a new KRL being created.
1.84 djm 576: .It Fl V Ar validity_interval
577: Specify a validity interval when signing a certificate.
578: A validity interval may consist of a single time, indicating that the
579: certificate is valid beginning now and expiring at that time, or may consist
580: of two times separated by a colon to indicate an explicit time interval.
1.145 djm 581: .Pp
582: The start time may be specified as the string
583: .Dq always
584: to indicate the certificate has no specified start time,
1.147 djm 585: a date in YYYYMMDD format, a time in YYYYMMDDHHMM[SS] format,
1.145 djm 586: a relative time (to the current time) consisting of a minus sign followed by
587: an interval in the format described in the
1.116 jmc 588: TIME FORMATS section of
1.90 jmc 589: .Xr sshd_config 5 .
1.145 djm 590: .Pp
1.147 djm 591: The end time may be specified as a YYYYMMDD date, a YYYYMMDDHHMM[SS] time,
1.145 djm 592: a relative time starting with a plus character or the string
593: .Dq forever
594: to indicate that the certificate has no expirty date.
1.84 djm 595: .Pp
596: For example:
597: .Dq +52w1d
598: (valid from now to 52 weeks and one day from now),
599: .Dq -4w:+4w
600: (valid from four weeks ago to four weeks from now),
601: .Dq 20100101123000:20110101123000
602: (valid from 12:30 PM, January 1st, 2010 to 12:30 PM, January 1st, 2011),
603: .Dq -1d:20110101
604: (valid from yesterday to midnight, January 1st, 2011).
1.145 djm 605: .Dq -1m:forever
606: (valid from one minute ago and never expiring).
1.61 djm 607: .It Fl v
608: Verbose mode.
609: Causes
610: .Nm
611: to print debugging messages about its progress.
612: This is helpful for debugging moduli generation.
613: Multiple
614: .Fl v
615: options increase the verbosity.
616: The maximum is 3.
1.173 naddy 617: .It Fl w Ar provider
1.180 naddy 618: Specifies a path to a library that will be used when creating
619: FIDO authenticator-hosted keys, overriding the default of using
620: the internal USB HID support.
1.194 djm 621: .It Fl Y Cm find-principal
622: Find the principal associated with the public key of a signature,
623: provided using the
624: .Fl s
625: flag in an authorized signers file provided using the
626: .Fl f
627: flag.
628: The format of the allowed signers file is documented in the
629: .Sx ALLOWED SIGNERS
1.195 ! jmc 630: section below.
! 631: If a matching principal is found, it is returned on standard output.
1.182 jmc 632: .It Fl Y Cm check-novalidate
633: Checks that a signature generated using
634: .Nm
635: .Fl Y Cm sign
636: has a valid structure.
637: This does not validate if a signature comes from an authorized signer.
638: When testing a signature,
639: .Nm
640: accepts a message on standard input and a signature namespace using
641: .Fl n .
642: A file containing the corresponding signature must also be supplied using the
643: .Fl s
644: flag.
645: Successful testing of the signature is signalled by
646: .Nm
647: returning a zero exit status.
1.166 jmc 648: .It Fl Y Cm sign
1.163 djm 649: Cryptographically sign a file or some data using a SSH key.
650: When signing,
651: .Nm
652: accepts zero or more files to sign on the command-line - if no files
653: are specified then
654: .Nm
655: will sign data presented on standard input.
656: Signatures are written to the path of the input file with
657: .Dq .sig
658: appended, or to standard output if the message to be signed was read from
659: standard input.
660: .Pp
661: The key used for signing is specified using the
662: .Fl f
663: option and may refer to either a private key, or a public key with the private
664: half available via
665: .Xr ssh-agent 1 .
666: An additional signature namespace, used to prevent signature confusion across
667: different domains of use (e.g. file signing vs email signing) must be provided
668: via the
669: .Fl n
670: flag.
671: Namespaces are arbitrary strings, and may include:
672: .Dq file
673: for file signing,
674: .Dq email
675: for email signing.
676: For custom uses, it is recommended to use names following a
677: NAMESPACE@YOUR.DOMAIN pattern to generate unambiguous namespaces.
1.166 jmc 678: .It Fl Y Cm verify
1.163 djm 679: Request to verify a signature generated using
680: .Nm
1.166 jmc 681: .Fl Y Cm sign
1.163 djm 682: as described above.
683: When verifying a signature,
684: .Nm
685: accepts a message on standard input and a signature namespace using
686: .Fl n .
687: A file containing the corresponding signature must also be supplied using the
688: .Fl s
689: flag, along with the identity of the signer using
690: .Fl I
691: and a list of allowed signers via the
692: .Fl f
693: flag.
694: The format of the allowed signers file is documented in the
695: .Sx ALLOWED SIGNERS
696: section below.
697: A file containing revoked keys can be passed using the
698: .Fl r
1.165 jmc 699: flag.
700: The revocation file may be a KRL or a one-per-line list of public keys.
1.163 djm 701: Successful verification by an authorized signer is signalled by
702: .Nm
703: returning a zero exit status.
1.181 jmc 704: .It Fl y
705: This option will read a private
706: OpenSSH format file and print an OpenSSH public key to stdout.
1.93 djm 707: .It Fl z Ar serial_number
708: Specifies a serial number to be embedded in the certificate to distinguish
709: this certificate from others from the same CA.
1.156 djm 710: If the
711: .Ar serial_number
712: is prefixed with a
713: .Sq +
714: character, then the serial number will be incremented for each certificate
715: signed on a single command-line.
1.93 djm 716: The default serial number is zero.
1.111 djm 717: .Pp
718: When generating a KRL, the
719: .Fl z
720: flag is used to specify a KRL version number.
1.2 deraadt 721: .El
1.60 djm 722: .Sh MODULI GENERATION
723: .Nm
724: may be used to generate groups for the Diffie-Hellman Group Exchange
725: (DH-GEX) protocol.
726: Generating these groups is a two-step process: first, candidate
727: primes are generated using a fast, but memory intensive process.
728: These candidate primes are then tested for suitability (a CPU-intensive
729: process).
730: .Pp
731: Generation of primes is performed using the
1.184 djm 732: .Fl M Cm generate
1.60 djm 733: option.
734: The desired length of the primes may be specified by the
1.184 djm 735: .Fl O Cm bits
1.60 djm 736: option.
737: For example:
738: .Pp
1.184 djm 739: .Dl # ssh-keygen -M generate -O bits=2048 moduli-2048.candidates
1.60 djm 740: .Pp
741: By default, the search for primes begins at a random point in the
742: desired length range.
743: This may be overridden using the
1.184 djm 744: .Fl O Cm start
1.60 djm 745: option, which specifies a different start point (in hex).
746: .Pp
1.109 dtucker 747: Once a set of candidates have been generated, they must be screened for
1.60 djm 748: suitability.
749: This may be performed using the
1.184 djm 750: .Fl M Cm screen
1.60 djm 751: option.
752: In this mode
753: .Nm
754: will read candidates from standard input (or a file specified using the
755: .Fl f
756: option).
757: For example:
758: .Pp
1.184 djm 759: .Dl # ssh-keygen -M screen -f moduli-2048.candidates moduli-2048
1.60 djm 760: .Pp
761: By default, each candidate will be subjected to 100 primality tests.
762: This may be overridden using the
1.184 djm 763: .Fl O Cm prime-tests
1.60 djm 764: option.
765: The DH generator value will be chosen automatically for the
766: prime under consideration.
767: If a specific generator is desired, it may be requested using the
1.184 djm 768: .Fl O Cm generator
1.60 djm 769: option.
1.66 jmc 770: Valid generator values are 2, 3, and 5.
1.60 djm 771: .Pp
772: Screened DH groups may be installed in
773: .Pa /etc/moduli .
774: It is important that this file contains moduli of a range of bit lengths and
775: that both ends of a connection share common moduli.
1.184 djm 776: .Pp
777: A number of options are available for moduli generation and screening via the
778: .Fl O
779: flag:
1.186 jmc 780: .Bl -tag -width Ds
1.184 djm 781: .It Ic lines Ns = Ns Ar number
782: Exit after screening the specified number of lines while performing DH
783: candidate screening.
784: .It Ic start-line Ns = Ns Ar line-number
785: Start screening at the specified line number while performing DH candidate
786: screening.
787: .It Ic checkpoint Ns = Ns Ar filename
788: Write the last line processed to the specified file while performing DH
789: candidate screening.
790: This will be used to skip lines in the input file that have already been
791: processed if the job is restarted.
792: .It Ic memory Ns = Ns Ar mbytes
793: Specify the amount of memory to use (in megabytes) when generating
794: candidate moduli for DH-GEX.
795: .It Ic start Ns = Ns Ar hex-value
796: Specify start point (in hex) when generating candidate moduli for DH-GEX.
797: .It Ic generator Ns = Ns Ar value
798: Specify desired generator (in decimal) when testing candidate moduli for DH-GEX.
799: .El
1.84 djm 800: .Sh CERTIFICATES
801: .Nm
802: supports signing of keys to produce certificates that may be used for
803: user or host authentication.
804: Certificates consist of a public key, some identity information, zero or
1.94 jmc 805: more principal (user or host) names and a set of options that
1.84 djm 806: are signed by a Certification Authority (CA) key.
807: Clients or servers may then trust only the CA key and verify its signature
808: on a certificate rather than trusting many user/host keys.
809: Note that OpenSSH certificates are a different, and much simpler, format to
810: the X.509 certificates used in
811: .Xr ssl 8 .
812: .Pp
813: .Nm
814: supports two types of certificates: user and host.
815: User certificates authenticate users to servers, whereas host certificates
1.85 jmc 816: authenticate server hosts to users.
817: To generate a user certificate:
1.84 djm 818: .Pp
819: .Dl $ ssh-keygen -s /path/to/ca_key -I key_id /path/to/user_key.pub
820: .Pp
821: The resultant certificate will be placed in
1.91 djm 822: .Pa /path/to/user_key-cert.pub .
1.84 djm 823: A host certificate requires the
824: .Fl h
825: option:
826: .Pp
827: .Dl $ ssh-keygen -s /path/to/ca_key -I key_id -h /path/to/host_key.pub
828: .Pp
829: The host certificate will be output to
1.91 djm 830: .Pa /path/to/host_key-cert.pub .
1.98 djm 831: .Pp
832: It is possible to sign using a CA key stored in a PKCS#11 token by
833: providing the token library using
834: .Fl D
835: and identifying the CA key by providing its public half as an argument
836: to
837: .Fl s :
838: .Pp
1.127 naddy 839: .Dl $ ssh-keygen -s ca_key.pub -D libpkcs11.so -I key_id user_key.pub
1.142 djm 840: .Pp
841: Similarly, it is possible for the CA key to be hosted in a
842: .Xr ssh-agent 1 .
843: This is indicated by the
844: .Fl U
845: flag and, again, the CA key must be identified by its public half.
846: .Pp
847: .Dl $ ssh-keygen -Us ca_key.pub -I key_id user_key.pub
1.98 djm 848: .Pp
849: In all cases,
1.84 djm 850: .Ar key_id
851: is a "key identifier" that is logged by the server when the certificate
852: is used for authentication.
853: .Pp
854: Certificates may be limited to be valid for a set of principal (user/host)
855: names.
856: By default, generated certificates are valid for all users or hosts.
857: To generate a certificate for a specified set of principals:
858: .Pp
859: .Dl $ ssh-keygen -s ca_key -I key_id -n user1,user2 user_key.pub
1.127 naddy 860: .Dl "$ ssh-keygen -s ca_key -I key_id -h -n host.domain host_key.pub"
1.84 djm 861: .Pp
862: Additional limitations on the validity and use of user certificates may
1.94 jmc 863: be specified through certificate options.
1.93 djm 864: A certificate option may disable features of the SSH session, may be
1.84 djm 865: valid only when presented from particular source addresses or may
866: force the use of a specific command.
1.183 djm 867: .Pp
868: The options that are valid for user certificates are:
869: .Pp
870: .Bl -tag -width Ds -compact
871: .It Ic clear
872: Clear all enabled permissions.
873: This is useful for clearing the default set of permissions so permissions may
874: be added individually.
875: .Pp
876: .It Ic critical : Ns Ar name Ns Op Ns = Ns Ar contents
877: .It Ic extension : Ns Ar name Ns Op Ns = Ns Ar contents
878: Includes an arbitrary certificate critical option or extension.
879: The specified
880: .Ar name
881: should include a domain suffix, e.g.\&
882: .Dq name@example.com .
883: If
884: .Ar contents
885: is specified then it is included as the contents of the extension/option
886: encoded as a string, otherwise the extension/option is created with no
887: contents (usually indicating a flag).
888: Extensions may be ignored by a client or server that does not recognise them,
889: whereas unknown critical options will cause the certificate to be refused.
890: .Pp
891: .It Ic force-command Ns = Ns Ar command
892: Forces the execution of
893: .Ar command
894: instead of any shell or command specified by the user when
895: the certificate is used for authentication.
896: .Pp
897: .It Ic no-agent-forwarding
898: Disable
899: .Xr ssh-agent 1
900: forwarding (permitted by default).
901: .Pp
902: .It Ic no-port-forwarding
903: Disable port forwarding (permitted by default).
904: .Pp
905: .It Ic no-pty
906: Disable PTY allocation (permitted by default).
907: .Pp
908: .It Ic no-user-rc
909: Disable execution of
910: .Pa ~/.ssh/rc
911: by
912: .Xr sshd 8
913: (permitted by default).
914: .Pp
915: .It Ic no-x11-forwarding
916: Disable X11 forwarding (permitted by default).
917: .Pp
918: .It Ic permit-agent-forwarding
919: Allows
920: .Xr ssh-agent 1
921: forwarding.
922: .Pp
923: .It Ic permit-port-forwarding
924: Allows port forwarding.
925: .Pp
926: .It Ic permit-pty
927: Allows PTY allocation.
928: .Pp
929: .It Ic permit-user-rc
930: Allows execution of
931: .Pa ~/.ssh/rc
932: by
933: .Xr sshd 8 .
934: .Pp
935: .It Ic permit-X11-forwarding
936: Allows X11 forwarding.
937: .Pp
938: .It Ic no-touch-required
939: Do not require signatures made using this key require demonstration
1.193 naddy 940: of user presence (e.g. by having the user touch the authenticator).
1.192 naddy 941: This option only makes sense for the FIDO authenticator algorithms
1.183 djm 942: .Cm ecdsa-sk
943: and
944: .Cm ed25519-sk .
945: .Pp
946: .It Ic source-address Ns = Ns Ar address_list
947: Restrict the source addresses from which the certificate is considered valid.
948: The
949: .Ar address_list
950: is a comma-separated list of one or more address/netmask pairs in CIDR
951: format.
952: .El
953: .Pp
954: At present, no standard options are valid for host keys.
1.84 djm 955: .Pp
956: Finally, certificates may be defined with a validity lifetime.
957: The
958: .Fl V
959: option allows specification of certificate start and end times.
960: A certificate that is presented at a time outside this range will not be
961: considered valid.
1.110 jmc 962: By default, certificates are valid from
963: .Ux
964: Epoch to the distant future.
1.84 djm 965: .Pp
966: For certificates to be used for user or host authentication, the CA
967: public key must be trusted by
968: .Xr sshd 8
969: or
970: .Xr ssh 1 .
971: Please refer to those manual pages for details.
1.111 djm 972: .Sh KEY REVOCATION LISTS
973: .Nm
974: is able to manage OpenSSH format Key Revocation Lists (KRLs).
975: These binary files specify keys or certificates to be revoked using a
1.119 tedu 976: compact format, taking as little as one bit per certificate if they are being
1.111 djm 977: revoked by serial number.
978: .Pp
979: KRLs may be generated using the
980: .Fl k
981: flag.
1.114 jmc 982: This option reads one or more files from the command line and generates a new
1.111 djm 983: KRL.
984: The files may either contain a KRL specification (see below) or public keys,
985: listed one per line.
986: Plain public keys are revoked by listing their hash or contents in the KRL and
987: certificates revoked by serial number or key ID (if the serial is zero or
988: not available).
989: .Pp
990: Revoking keys using a KRL specification offers explicit control over the
991: types of record used to revoke keys and may be used to directly revoke
992: certificates by serial number or key ID without having the complete original
993: certificate on hand.
994: A KRL specification consists of lines containing one of the following directives
995: followed by a colon and some directive-specific information.
996: .Bl -tag -width Ds
1.115 jmc 997: .It Cm serial : Ar serial_number Ns Op - Ns Ar serial_number
1.111 djm 998: Revokes a certificate with the specified serial number.
1.112 jmc 999: Serial numbers are 64-bit values, not including zero and may be expressed
1.111 djm 1000: in decimal, hex or octal.
1001: If two serial numbers are specified separated by a hyphen, then the range
1002: of serial numbers including and between each is revoked.
1003: The CA key must have been specified on the
1004: .Nm
1.114 jmc 1005: command line using the
1.111 djm 1006: .Fl s
1007: option.
1008: .It Cm id : Ar key_id
1009: Revokes a certificate with the specified key ID string.
1010: The CA key must have been specified on the
1011: .Nm
1.114 jmc 1012: command line using the
1.111 djm 1013: .Fl s
1014: option.
1015: .It Cm key : Ar public_key
1016: Revokes the specified key.
1.112 jmc 1017: If a certificate is listed, then it is revoked as a plain public key.
1.111 djm 1018: .It Cm sha1 : Ar public_key
1.149 djm 1019: Revokes the specified key by including its SHA1 hash in the KRL.
1020: .It Cm sha256 : Ar public_key
1021: Revokes the specified key by including its SHA256 hash in the KRL.
1022: KRLs that revoke keys by SHA256 hash are not supported by OpenSSH versions
1023: prior to 7.9.
1024: .It Cm hash : Ar fingerprint
1.150 djm 1025: Revokes a key using a fingerprint hash, as obtained from a
1.149 djm 1026: .Xr sshd 8
1027: authentication log message or the
1028: .Nm
1029: .Fl l
1030: flag.
1031: Only SHA256 fingerprints are supported here and resultant KRLs are
1032: not supported by OpenSSH versions prior to 7.9.
1.111 djm 1033: .El
1034: .Pp
1035: KRLs may be updated using the
1036: .Fl u
1037: flag in addition to
1038: .Fl k .
1.114 jmc 1039: When this option is specified, keys listed via the command line are merged into
1.111 djm 1040: the KRL, adding to those already there.
1041: .Pp
1042: It is also possible, given a KRL, to test whether it revokes a particular key
1043: (or keys).
1044: The
1045: .Fl Q
1.128 jmc 1046: flag will query an existing KRL, testing each key specified on the command line.
1.114 jmc 1047: If any key listed on the command line has been revoked (or an error encountered)
1.111 djm 1048: then
1049: .Nm
1050: will exit with a non-zero exit status.
1051: A zero exit status will only be returned if no key was revoked.
1.163 djm 1052: .Sh ALLOWED SIGNERS
1053: When verifying signatures,
1054: .Nm
1055: uses a simple list of identities and keys to determine whether a signature
1056: comes from an authorized source.
1057: This "allowed signers" file uses a format patterned after the
1058: AUTHORIZED_KEYS FILE FORMAT described in
1.165 jmc 1059: .Xr sshd 8 .
1.163 djm 1060: Each line of the file contains the following space-separated fields:
1061: principals, options, keytype, base64-encoded key.
1062: Empty lines and lines starting with a
1063: .Ql #
1064: are ignored as comments.
1065: .Pp
1066: The principals field is a pattern-list (See PATTERNS in
1067: .Xr ssh_config 5 )
1068: consisting of one or more comma-separated USER@DOMAIN identity patterns
1069: that are accepted for signing.
1070: When verifying, the identity presented via the
1.172 jmc 1071: .Fl I
1072: option must match a principals pattern in order for the corresponding key to be
1.163 djm 1073: considered acceptable for verification.
1074: .Pp
1075: The options (if present) consist of comma-separated option specifications.
1076: No spaces are permitted, except within double quotes.
1077: The following option specifications are supported (note that option keywords
1078: are case-insensitive):
1079: .Bl -tag -width Ds
1080: .It Cm cert-authority
1081: Indicates that this key is accepted as a certificate authority (CA) and
1082: that certificates signed by this CA may be accepted for verification.
1083: .It Cm namespaces="namespace-list"
1084: Specifies a pattern-list of namespaces that are accepted for this key.
1.164 djm 1085: If this option is present, the signature namespace embedded in the
1.163 djm 1086: signature object and presented on the verification command-line must
1087: match the specified list before the key will be considered acceptable.
1088: .El
1089: .Pp
1090: When verifying signatures made by certificates, the expected principal
1091: name must match both the principals pattern in the allowed signers file and
1092: the principals embedded in the certificate itself.
1093: .Pp
1094: An example allowed signers file:
1095: .Bd -literal -offset 3n
1096: # Comments allowed at start of line
1097: user1@example.com,user2@example.com ssh-rsa AAAAX1...
1098: # A certificate authority, trusted for all principals in a domain.
1099: *@example.com cert-authority ssh-ed25519 AAAB4...
1100: # A key that is accepted only for file signing.
1101: user2@example.com namespaces="file" ssh-ed25519 AAA41...
1102: .Ed
1.173 naddy 1103: .Sh ENVIRONMENT
1104: .Bl -tag -width Ds
1105: .It Ev SSH_SK_PROVIDER
1.180 naddy 1106: Specifies the path to a library used to interact with FIDO authenticators.
1.173 naddy 1107: .El
1.2 deraadt 1108: .Sh FILES
1.100 naddy 1109: .Bl -tag -width Ds -compact
1.68 djm 1110: .It Pa ~/.ssh/id_dsa
1.100 naddy 1111: .It Pa ~/.ssh/id_ecdsa
1.173 naddy 1112: .It Pa ~/.ssh/id_ecdsa_sk
1.118 naddy 1113: .It Pa ~/.ssh/id_ed25519
1.176 naddy 1114: .It Pa ~/.ssh/id_ed25519_sk
1.100 naddy 1115: .It Pa ~/.ssh/id_rsa
1.180 naddy 1116: Contains the DSA, ECDSA, authenticator-hosted ECDSA, Ed25519,
1117: authenticator-hosted Ed25519 or RSA authentication identity of the user.
1.15 deraadt 1118: This file should not be readable by anyone but the user.
1119: It is possible to
1120: specify a passphrase when generating the key; that passphrase will be
1.80 dtucker 1121: used to encrypt the private part of this file using 128-bit AES.
1.15 deraadt 1122: This file is not automatically accessed by
1123: .Nm
1124: but it is offered as the default file for the private key.
1.46 markus 1125: .Xr ssh 1
1.15 deraadt 1126: will read this file when a login attempt is made.
1.100 naddy 1127: .Pp
1.68 djm 1128: .It Pa ~/.ssh/id_dsa.pub
1.100 naddy 1129: .It Pa ~/.ssh/id_ecdsa.pub
1.173 naddy 1130: .It Pa ~/.ssh/id_ecdsa_sk.pub
1.118 naddy 1131: .It Pa ~/.ssh/id_ed25519.pub
1.176 naddy 1132: .It Pa ~/.ssh/id_ed25519_sk.pub
1.68 djm 1133: .It Pa ~/.ssh/id_rsa.pub
1.180 naddy 1134: Contains the DSA, ECDSA, authenticator-hosted ECDSA, Ed25519,
1135: authenticator-hosted Ed25519 or RSA public key for authentication.
1.15 deraadt 1136: The contents of this file should be added to
1.68 djm 1137: .Pa ~/.ssh/authorized_keys
1.15 deraadt 1138: on all machines
1.49 deraadt 1139: where the user wishes to log in using public key authentication.
1.12 aaron 1140: There is no need to keep the contents of this file secret.
1.100 naddy 1141: .Pp
1.60 djm 1142: .It Pa /etc/moduli
1143: Contains Diffie-Hellman groups used for DH-GEX.
1144: The file format is described in
1145: .Xr moduli 5 .
1.19 aaron 1146: .El
1.2 deraadt 1147: .Sh SEE ALSO
1148: .Xr ssh 1 ,
1149: .Xr ssh-add 1 ,
1.8 ericj 1150: .Xr ssh-agent 1 ,
1.60 djm 1151: .Xr moduli 5 ,
1.30 itojun 1152: .Xr sshd 8
1.37 markus 1153: .Rs
1.73 markus 1154: .%R RFC 4716
1155: .%T "The Secure Shell (SSH) Public Key File Format"
1156: .%D 2006
1.37 markus 1157: .Re
1.59 jmc 1158: .Sh AUTHORS
1159: OpenSSH is a derivative of the original and free
1160: ssh 1.2.12 release by Tatu Ylonen.
1161: Aaron Campbell, Bob Beck, Markus Friedl, Niels Provos,
1162: Theo de Raadt and Dug Song
1163: removed many bugs, re-added newer features and
1164: created OpenSSH.
1165: Markus Friedl contributed the support for SSH
1166: protocol versions 1.5 and 2.0.