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diff --git a/crypto/openssh/ssh-keygen.1 b/crypto/openssh/ssh-keygen.1 new file mode 100644 index 0000000..6c55c22 --- /dev/null +++ b/crypto/openssh/ssh-keygen.1 @@ -0,0 +1,689 @@ +.\" $OpenBSD: ssh-keygen.1,v 1.106 2011/04/13 04:09:37 djm Exp $ +.\" $FreeBSD$ +.\" +.\" Author: Tatu Ylonen <ylo@cs.hut.fi> +.\" Copyright (c) 1995 Tatu Ylonen <ylo@cs.hut.fi>, Espoo, Finland +.\" All rights reserved +.\" +.\" As far as I am concerned, the code I have written for this software +.\" can be used freely for any purpose. Any derived versions of this +.\" software must be clearly marked as such, and if the derived work is +.\" incompatible with the protocol description in the RFC file, it must be +.\" called by a name other than "ssh" or "Secure Shell". +.\" +.\" +.\" Copyright (c) 1999,2000 Markus Friedl. All rights reserved. +.\" Copyright (c) 1999 Aaron Campbell. All rights reserved. +.\" Copyright (c) 1999 Theo de Raadt. All rights reserved. +.\" +.\" Redistribution and use in source and binary forms, with or without +.\" modification, are permitted provided that the following conditions +.\" are met: +.\" 1. Redistributions of source code must retain the above copyright +.\" notice, this list of conditions and the following disclaimer. +.\" 2. Redistributions in binary form must reproduce the above copyright +.\" notice, this list of conditions and the following disclaimer in the +.\" documentation and/or other materials provided with the distribution. +.\" +.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR +.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES +.\" OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. +.\" IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, +.\" INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT +.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, +.\" DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY +.\" THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT +.\" (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF +.\" THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. +.\" +.Dd April 13, 2011 +.Dt SSH-KEYGEN 1 +.Os +.Sh NAME +.Nm ssh-keygen +.Nd authentication key generation, management and conversion +.Sh SYNOPSIS +.Bk -words +.Nm ssh-keygen +.Op Fl q +.Op Fl b Ar bits +.Fl t Ar type +.Op Fl N Ar new_passphrase +.Op Fl C Ar comment +.Op Fl f Ar output_keyfile +.Nm ssh-keygen +.Fl p +.Op Fl P Ar old_passphrase +.Op Fl N Ar new_passphrase +.Op Fl f Ar keyfile +.Nm ssh-keygen +.Fl i +.Op Fl m Ar key_format +.Op Fl f Ar input_keyfile +.Nm ssh-keygen +.Fl e +.Op Fl m Ar key_format +.Op Fl f Ar input_keyfile +.Nm ssh-keygen +.Fl y +.Op Fl f Ar input_keyfile +.Nm ssh-keygen +.Fl c +.Op Fl P Ar passphrase +.Op Fl C Ar comment +.Op Fl f Ar keyfile +.Nm ssh-keygen +.Fl l +.Op Fl f Ar input_keyfile +.Nm ssh-keygen +.Fl B +.Op Fl f Ar input_keyfile +.Nm ssh-keygen +.Fl D Ar pkcs11 +.Nm ssh-keygen +.Fl F Ar hostname +.Op Fl f Ar known_hosts_file +.Op Fl l +.Nm ssh-keygen +.Fl H +.Op Fl f Ar known_hosts_file +.Nm ssh-keygen +.Fl R Ar hostname +.Op Fl f Ar known_hosts_file +.Nm ssh-keygen +.Fl r Ar hostname +.Op Fl f Ar input_keyfile +.Op Fl g +.Nm ssh-keygen +.Fl G Ar output_file +.Op Fl v +.Op Fl b Ar bits +.Op Fl M Ar memory +.Op Fl S Ar start_point +.Nm ssh-keygen +.Fl T Ar output_file +.Fl f Ar input_file +.Op Fl v +.Op Fl a Ar num_trials +.Op Fl W Ar generator +.Nm ssh-keygen +.Fl s Ar ca_key +.Fl I Ar certificate_identity +.Op Fl h +.Op Fl n Ar principals +.Op Fl O Ar option +.Op Fl V Ar validity_interval +.Op Fl z Ar serial_number +.Ar +.Nm ssh-keygen +.Fl L +.Op Fl f Ar input_keyfile +.Nm ssh-keygen +.Fl A +.Ek +.Sh DESCRIPTION +.Nm +generates, manages and converts authentication keys for +.Xr ssh 1 . +.Nm +can create RSA keys for use by SSH protocol version 1 and DSA, ECDSA or RSA +keys for use by SSH protocol version 2. +The type of key to be generated is specified with the +.Fl t +option. +If invoked without any arguments, +.Nm +will generate an RSA key for use in SSH protocol 2 connections. +.Pp +.Nm +is also used to generate groups for use in Diffie-Hellman group +exchange (DH-GEX). +See the +.Sx MODULI GENERATION +section for details. +.Pp +Normally each user wishing to use SSH +with public key authentication runs this once to create the authentication +key in +.Pa ~/.ssh/identity , +.Pa ~/.ssh/id_ecdsa , +.Pa ~/.ssh/id_dsa +or +.Pa ~/.ssh/id_rsa . +Additionally, the system administrator may use this to generate host keys, +as seen in +.Pa /etc/rc . +.Pp +Normally this program generates the key and asks for a file in which +to store the private key. +The public key is stored in a file with the same name but +.Dq .pub +appended. +The program also asks for a passphrase. +The passphrase may be empty to indicate no passphrase +(host keys must have an empty passphrase), or it may be a string of +arbitrary length. +A passphrase is similar to a password, except it can be a phrase with a +series of words, punctuation, numbers, whitespace, or any string of +characters you want. +Good passphrases are 10-30 characters long, are +not simple sentences or otherwise easily guessable (English +prose has only 1-2 bits of entropy per character, and provides very bad +passphrases), and contain a mix of upper and lowercase letters, +numbers, and non-alphanumeric characters. +The passphrase can be changed later by using the +.Fl p +option. +.Pp +There is no way to recover a lost passphrase. +If the passphrase is lost or forgotten, a new key must be generated +and the corresponding public key copied to other machines. +.Pp +For RSA1 keys, +there is also a comment field in the key file that is only for +convenience to the user to help identify the key. +The comment can tell what the key is for, or whatever is useful. +The comment is initialized to +.Dq user@host +when the key is created, but can be changed using the +.Fl c +option. +.Pp +After a key is generated, instructions below detail where the keys +should be placed to be activated. +.Pp +The options are as follows: +.Bl -tag -width Ds +.It Fl A +For each of the key types (rsa1, rsa, dsa and ecdsa) for which host keys +do not exist, generate the host keys with the default key file path, +an empty passphrase, default bits for the key type, and default comment. +This is used by +.Pa /etc/rc +to generate new host keys. +.It Fl a Ar trials +Specifies the number of primality tests to perform when screening DH-GEX +candidates using the +.Fl T +command. +.It Fl B +Show the bubblebabble digest of specified private or public key file. +.It Fl b Ar bits +Specifies the number of bits in the key to create. +For RSA keys, the minimum size is 768 bits and the default is 2048 bits. +Generally, 2048 bits is considered sufficient. +DSA keys must be exactly 1024 bits as specified by FIPS 186-2. +For ECDSA keys, the +.Fl b +flag determines they key length by selecting from one of three elliptic +curve sizes: 256, 384 or 521 bits. +Attempting to use bit lengths other than these three values for ECDSA keys +will fail. +.It Fl C Ar comment +Provides a new comment. +.It Fl c +Requests changing the comment in the private and public key files. +This operation is only supported for RSA1 keys. +The program will prompt for the file containing the private keys, for +the passphrase if the key has one, and for the new comment. +.It Fl D Ar pkcs11 +Download the RSA public keys provided by the PKCS#11 shared library +.Ar pkcs11 . +When used in combination with +.Fl s , +this option indicates that a CA key resides in a PKCS#11 token (see the +.Sx CERTIFICATES +section for details). +.It Fl e +This option will read a private or public OpenSSH key file and +print to stdout the key in one of the formats specified by the +.Fl m +option. +The default export format is +.Dq RFC4716 . +This option allows exporting OpenSSH keys for use by other programs, including +several commercial SSH implementations. +.It Fl F Ar hostname +Search for the specified +.Ar hostname +in a +.Pa known_hosts +file, listing any occurrences found. +This option is useful to find hashed host names or addresses and may also be +used in conjunction with the +.Fl H +option to print found keys in a hashed format. +.It Fl f Ar filename +Specifies the filename of the key file. +.It Fl G Ar output_file +Generate candidate primes for DH-GEX. +These primes must be screened for +safety (using the +.Fl T +option) before use. +.It Fl g +Use generic DNS format when printing fingerprint resource records using the +.Fl r +command. +.It Fl H +Hash a +.Pa known_hosts +file. +This replaces all hostnames and addresses with hashed representations +within the specified file; the original content is moved to a file with +a .old suffix. +These hashes may be used normally by +.Nm ssh +and +.Nm sshd , +but they do not reveal identifying information should the file's contents +be disclosed. +This option will not modify existing hashed hostnames and is therefore safe +to use on files that mix hashed and non-hashed names. +.It Fl h +When signing a key, create a host certificate instead of a user +certificate. +Please see the +.Sx CERTIFICATES +section for details. +.It Fl I Ar certificate_identity +Specify the key identity when signing a public key. +Please see the +.Sx CERTIFICATES +section for details. +.It Fl i +This option will read an unencrypted private (or public) key file +in the format specified by the +.Fl m +option and print an OpenSSH compatible private +(or public) key to stdout. +This option allows importing keys from other software, including several +commercial SSH implementations. +The default import format is +.Dq RFC4716 . +.It Fl L +Prints the contents of a certificate. +.It Fl l +Show fingerprint of specified public key file. +Private RSA1 keys are also supported. +For RSA and DSA keys +.Nm +tries to find the matching public key file and prints its fingerprint. +If combined with +.Fl v , +an ASCII art representation of the key is supplied with the fingerprint. +.It Fl M Ar memory +Specify the amount of memory to use (in megabytes) when generating +candidate moduli for DH-GEX. +.It Fl m Ar key_format +Specify a key format for the +.Fl i +(import) or +.Fl e +(export) conversion options. +The supported key formats are: +.Dq RFC4716 +(RFC 4716/SSH2 public or private key), +.Dq PKCS8 +(PEM PKCS8 public key) +or +.Dq PEM +(PEM public key). +The default conversion format is +.Dq RFC4716 . +.It Fl N Ar new_passphrase +Provides the new passphrase. +.It Fl n Ar principals +Specify one or more principals (user or host names) to be included in +a certificate when signing a key. +Multiple principals may be specified, separated by commas. +Please see the +.Sx CERTIFICATES +section for details. +.It Fl O Ar option +Specify a certificate option when signing a key. +This option may be specified multiple times. +Please see the +.Sx CERTIFICATES +section for details. +The options that are valid for user certificates are: +.Bl -tag -width Ds +.It Ic clear +Clear all enabled permissions. +This is useful for clearing the default set of permissions so permissions may +be added individually. +.It Ic force-command Ns = Ns Ar command +Forces the execution of +.Ar command +instead of any shell or command specified by the user when +the certificate is used for authentication. +.It Ic no-agent-forwarding +Disable +.Xr ssh-agent 1 +forwarding (permitted by default). +.It Ic no-port-forwarding +Disable port forwarding (permitted by default). +.It Ic no-pty +Disable PTY allocation (permitted by default). +.It Ic no-user-rc +Disable execution of +.Pa ~/.ssh/rc +by +.Xr sshd 8 +(permitted by default). +.It Ic no-x11-forwarding +Disable X11 forwarding (permitted by default). +.It Ic permit-agent-forwarding +Allows +.Xr ssh-agent 1 +forwarding. +.It Ic permit-port-forwarding +Allows port forwarding. +.It Ic permit-pty +Allows PTY allocation. +.It Ic permit-user-rc +Allows execution of +.Pa ~/.ssh/rc +by +.Xr sshd 8 . +.It Ic permit-x11-forwarding +Allows X11 forwarding. +.It Ic source-address Ns = Ns Ar address_list +Restrict the source addresses from which the certificate is considered valid. +The +.Ar address_list +is a comma-separated list of one or more address/netmask pairs in CIDR +format. +.El +.Pp +At present, no options are valid for host keys. +.It Fl P Ar passphrase +Provides the (old) passphrase. +.It Fl p +Requests changing the passphrase of a private key file instead of +creating a new private key. +The program will prompt for the file +containing the private key, for the old passphrase, and twice for the +new passphrase. +.It Fl q +Silence +.Nm ssh-keygen . +.It Fl R Ar hostname +Removes all keys belonging to +.Ar hostname +from a +.Pa known_hosts +file. +This option is useful to delete hashed hosts (see the +.Fl H +option above). +.It Fl r Ar hostname +Print the SSHFP fingerprint resource record named +.Ar hostname +for the specified public key file. +.It Fl S Ar start +Specify start point (in hex) when generating candidate moduli for DH-GEX. +.It Fl s Ar ca_key +Certify (sign) a public key using the specified CA key. +Please see the +.Sx CERTIFICATES +section for details. +.It Fl T Ar output_file +Test DH group exchange candidate primes (generated using the +.Fl G +option) for safety. +.It Fl t Ar type +Specifies the type of key to create. +The possible values are +.Dq rsa1 +for protocol version 1 and +.Dq dsa , +.Dq ecdsa +or +.Dq rsa +for protocol version 2. +.It Fl V Ar validity_interval +Specify a validity interval when signing a certificate. +A validity interval may consist of a single time, indicating that the +certificate is valid beginning now and expiring at that time, or may consist +of two times separated by a colon to indicate an explicit time interval. +The start time may be specified as a date in YYYYMMDD format, a time +in YYYYMMDDHHMMSS format or a relative time (to the current time) consisting +of a minus sign followed by a relative time in the format described in the +.Sx TIME FORMATS +section of +.Xr sshd_config 5 . +The end time may be specified as a YYYYMMDD date, a YYYYMMDDHHMMSS time or +a relative time starting with a plus character. +.Pp +For example: +.Dq +52w1d +(valid from now to 52 weeks and one day from now), +.Dq -4w:+4w +(valid from four weeks ago to four weeks from now), +.Dq 20100101123000:20110101123000 +(valid from 12:30 PM, January 1st, 2010 to 12:30 PM, January 1st, 2011), +.Dq -1d:20110101 +(valid from yesterday to midnight, January 1st, 2011). +.It Fl v +Verbose mode. +Causes +.Nm +to print debugging messages about its progress. +This is helpful for debugging moduli generation. +Multiple +.Fl v +options increase the verbosity. +The maximum is 3. +.It Fl W Ar generator +Specify desired generator when testing candidate moduli for DH-GEX. +.It Fl y +This option will read a private +OpenSSH format file and print an OpenSSH public key to stdout. +.It Fl z Ar serial_number +Specifies a serial number to be embedded in the certificate to distinguish +this certificate from others from the same CA. +The default serial number is zero. +.El +.Sh MODULI GENERATION +.Nm +may be used to generate groups for the Diffie-Hellman Group Exchange +(DH-GEX) protocol. +Generating these groups is a two-step process: first, candidate +primes are generated using a fast, but memory intensive process. +These candidate primes are then tested for suitability (a CPU-intensive +process). +.Pp +Generation of primes is performed using the +.Fl G +option. +The desired length of the primes may be specified by the +.Fl b +option. +For example: +.Pp +.Dl # ssh-keygen -G moduli-2048.candidates -b 2048 +.Pp +By default, the search for primes begins at a random point in the +desired length range. +This may be overridden using the +.Fl S +option, which specifies a different start point (in hex). +.Pp +Once a set of candidates have been generated, they must be tested for +suitability. +This may be performed using the +.Fl T +option. +In this mode +.Nm +will read candidates from standard input (or a file specified using the +.Fl f +option). +For example: +.Pp +.Dl # ssh-keygen -T moduli-2048 -f moduli-2048.candidates +.Pp +By default, each candidate will be subjected to 100 primality tests. +This may be overridden using the +.Fl a +option. +The DH generator value will be chosen automatically for the +prime under consideration. +If a specific generator is desired, it may be requested using the +.Fl W +option. +Valid generator values are 2, 3, and 5. +.Pp +Screened DH groups may be installed in +.Pa /etc/moduli . +It is important that this file contains moduli of a range of bit lengths and +that both ends of a connection share common moduli. +.Sh CERTIFICATES +.Nm +supports signing of keys to produce certificates that may be used for +user or host authentication. +Certificates consist of a public key, some identity information, zero or +more principal (user or host) names and a set of options that +are signed by a Certification Authority (CA) key. +Clients or servers may then trust only the CA key and verify its signature +on a certificate rather than trusting many user/host keys. +Note that OpenSSH certificates are a different, and much simpler, format to +the X.509 certificates used in +.Xr ssl 8 . +.Pp +.Nm +supports two types of certificates: user and host. +User certificates authenticate users to servers, whereas host certificates +authenticate server hosts to users. +To generate a user certificate: +.Pp +.Dl $ ssh-keygen -s /path/to/ca_key -I key_id /path/to/user_key.pub +.Pp +The resultant certificate will be placed in +.Pa /path/to/user_key-cert.pub . +A host certificate requires the +.Fl h +option: +.Pp +.Dl $ ssh-keygen -s /path/to/ca_key -I key_id -h /path/to/host_key.pub +.Pp +The host certificate will be output to +.Pa /path/to/host_key-cert.pub . +.Pp +It is possible to sign using a CA key stored in a PKCS#11 token by +providing the token library using +.Fl D +and identifying the CA key by providing its public half as an argument +to +.Fl s : +.Pp +.Dl $ ssh-keygen -s ca_key.pub -D libpkcs11.so -I key_id host_key.pub +.Pp +In all cases, +.Ar key_id +is a "key identifier" that is logged by the server when the certificate +is used for authentication. +.Pp +Certificates may be limited to be valid for a set of principal (user/host) +names. +By default, generated certificates are valid for all users or hosts. +To generate a certificate for a specified set of principals: +.Pp +.Dl $ ssh-keygen -s ca_key -I key_id -n user1,user2 user_key.pub +.Dl "$ ssh-keygen -s ca_key -I key_id -h -n host.domain user_key.pub" +.Pp +Additional limitations on the validity and use of user certificates may +be specified through certificate options. +A certificate option may disable features of the SSH session, may be +valid only when presented from particular source addresses or may +force the use of a specific command. +For a list of valid certificate options, see the documentation for the +.Fl O +option above. +.Pp +Finally, certificates may be defined with a validity lifetime. +The +.Fl V +option allows specification of certificate start and end times. +A certificate that is presented at a time outside this range will not be +considered valid. +By default, certificates have a maximum validity interval. +.Pp +For certificates to be used for user or host authentication, the CA +public key must be trusted by +.Xr sshd 8 +or +.Xr ssh 1 . +Please refer to those manual pages for details. +.Sh FILES +.Bl -tag -width Ds -compact +.It Pa ~/.ssh/identity +Contains the protocol version 1 RSA authentication identity of the user. +This file should not be readable by anyone but the user. +It is possible to +specify a passphrase when generating the key; that passphrase will be +used to encrypt the private part of this file using 3DES. +This file is not automatically accessed by +.Nm +but it is offered as the default file for the private key. +.Xr ssh 1 +will read this file when a login attempt is made. +.Pp +.It Pa ~/.ssh/identity.pub +Contains the protocol version 1 RSA public key for authentication. +The contents of this file should be added to +.Pa ~/.ssh/authorized_keys +on all machines +where the user wishes to log in using RSA authentication. +There is no need to keep the contents of this file secret. +.Pp +.It Pa ~/.ssh/id_dsa +.It Pa ~/.ssh/id_ecdsa +.It Pa ~/.ssh/id_rsa +Contains the protocol version 2 DSA, ECDSA or RSA authentication identity of the user. +This file should not be readable by anyone but the user. +It is possible to +specify a passphrase when generating the key; that passphrase will be +used to encrypt the private part of this file using 128-bit AES. +This file is not automatically accessed by +.Nm +but it is offered as the default file for the private key. +.Xr ssh 1 +will read this file when a login attempt is made. +.Pp +.It Pa ~/.ssh/id_dsa.pub +.It Pa ~/.ssh/id_ecdsa.pub +.It Pa ~/.ssh/id_rsa.pub +Contains the protocol version 2 DSA, ECDSA or RSA public key for authentication. +The contents of this file should be added to +.Pa ~/.ssh/authorized_keys +on all machines +where the user wishes to log in using public key authentication. +There is no need to keep the contents of this file secret. +.Pp +.It Pa /etc/moduli +Contains Diffie-Hellman groups used for DH-GEX. +The file format is described in +.Xr moduli 5 . +.El +.Sh SEE ALSO +.Xr ssh 1 , +.Xr ssh-add 1 , +.Xr ssh-agent 1 , +.Xr moduli 5 , +.Xr sshd 8 +.Rs +.%R RFC 4716 +.%T "The Secure Shell (SSH) Public Key File Format" +.%D 2006 +.Re +.Sh AUTHORS +OpenSSH is a derivative of the original and free +ssh 1.2.12 release by Tatu Ylonen. +Aaron Campbell, Bob Beck, Markus Friedl, Niels Provos, +Theo de Raadt and Dug Song +removed many bugs, re-added newer features and +created OpenSSH. +Markus Friedl contributed the support for SSH +protocol versions 1.5 and 2.0. |