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diff --git a/ssh-keygen.0 b/ssh-keygen.0 new file mode 100644 index 0000000..906a338 --- /dev/null +++ b/ssh-keygen.0 @@ -0,0 +1,585 @@ +SSH-KEYGEN(1) General Commands Manual SSH-KEYGEN(1) + +NAME + ssh-keygen M-bM-^@M-^S authentication key generation, management and conversion + +SYNOPSIS + ssh-keygen [-q] [-b bits] [-t dsa | ecdsa | ed25519 | rsa] + [-N new_passphrase] [-C comment] [-f output_keyfile] + ssh-keygen -p [-P old_passphrase] [-N new_passphrase] [-f keyfile] + ssh-keygen -i [-m key_format] [-f input_keyfile] + ssh-keygen -e [-m key_format] [-f input_keyfile] + ssh-keygen -y [-f input_keyfile] + ssh-keygen -c [-P passphrase] [-C comment] [-f keyfile] + ssh-keygen -l [-v] [-E fingerprint_hash] [-f input_keyfile] + ssh-keygen -B [-f input_keyfile] + ssh-keygen -D pkcs11 + ssh-keygen -F hostname [-f known_hosts_file] [-l] + ssh-keygen -H [-f known_hosts_file] + ssh-keygen -R hostname [-f known_hosts_file] + ssh-keygen -r hostname [-f input_keyfile] [-g] + ssh-keygen -G output_file [-v] [-b bits] [-M memory] [-S start_point] + ssh-keygen -T output_file -f input_file [-v] [-a rounds] [-J num_lines] + [-j start_line] [-K checkpt] [-W generator] + ssh-keygen -s ca_key -I certificate_identity [-h] [-U] + [-D pkcs11_provider] [-n principals] [-O option] + [-V validity_interval] [-z serial_number] file ... + ssh-keygen -L [-f input_keyfile] + ssh-keygen -A [-f prefix_path] + ssh-keygen -k -f krl_file [-u] [-s ca_public] [-z version_number] + file ... + ssh-keygen -Q -f krl_file file ... + +DESCRIPTION + ssh-keygen generates, manages and converts authentication keys for + ssh(1). ssh-keygen can create keys for use by SSH protocol version 2. + + The type of key to be generated is specified with the -t option. If + invoked without any arguments, ssh-keygen will generate an RSA key. + + ssh-keygen is also used to generate groups for use in Diffie-Hellman + group exchange (DH-GEX). See the MODULI GENERATION section for details. + + Finally, ssh-keygen can be used to generate and update Key Revocation + Lists, and to test whether given keys have been revoked by one. See the + KEY REVOCATION LISTS section for details. + + Normally each user wishing to use SSH with public key authentication runs + this once to create the authentication key in ~/.ssh/id_dsa, + ~/.ssh/id_ecdsa, ~/.ssh/id_ed25519 or ~/.ssh/id_rsa. Additionally, the + system administrator may use this to generate host keys, as seen in + /etc/rc. + + 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 M-bM-^@M-^\.pubM-bM-^@M-^] 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 -p option. + + 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. + + For keys stored in the newer OpenSSH format, 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 M-bM-^@M-^\user@hostM-bM-^@M-^] when the key is + created, but can be changed using the -c option. + + After a key is generated, instructions below detail where the keys should + be placed to be activated. + + The options are as follows: + + -A For each of the key types (rsa, dsa, ecdsa and ed25519) 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. If -f has also been specified, its + argument is used as a prefix to the default path for the + resulting host key files. This is used by /etc/rc to generate + new host keys. + + -a rounds + When saving a private key this option specifies the number of KDF + (key derivation function) rounds used. Higher numbers result in + slower passphrase verification and increased resistance to brute- + force password cracking (should the keys be stolen). + + When screening DH-GEX candidates (using the -T command). This + option specifies the number of primality tests to perform. + + -B Show the bubblebabble digest of specified private or public key + file. + + -b bits + Specifies the number of bits in the key to create. For RSA keys, + the minimum size is 1024 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 -b flag determines the 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. Ed25519 keys have a fixed length and the -b flag will be + ignored. + + -C comment + Provides a new comment. + + -c Requests changing the comment in the private and public key + files. The program will prompt for the file containing the + private keys, for the passphrase if the key has one, and for the + new comment. + + -D pkcs11 + Download the RSA public keys provided by the PKCS#11 shared + library pkcs11. When used in combination with -s, this option + indicates that a CA key resides in a PKCS#11 token (see the + CERTIFICATES section for details). + + -E fingerprint_hash + Specifies the hash algorithm used when displaying key + fingerprints. Valid options are: M-bM-^@M-^\md5M-bM-^@M-^] and M-bM-^@M-^\sha256M-bM-^@M-^]. The + default is M-bM-^@M-^\sha256M-bM-^@M-^]. + + -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 -m + option. The default export format is M-bM-^@M-^\RFC4716M-bM-^@M-^]. This option + allows exporting OpenSSH keys for use by other programs, + including several commercial SSH implementations. + + -F hostname + Search for the specified hostname in a 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 + -H option to print found keys in a hashed format. + + -f filename + Specifies the filename of the key file. + + -G output_file + Generate candidate primes for DH-GEX. These primes must be + screened for safety (using the -T option) before use. + + -g Use generic DNS format when printing fingerprint resource records + using the -r command. + + -H Hash a 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 ssh and 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. + + -h When signing a key, create a host certificate instead of a user + certificate. Please see the CERTIFICATES section for details. + + -I certificate_identity + Specify the key identity when signing a public key. Please see + the CERTIFICATES section for details. + + -i This option will read an unencrypted private (or public) key file + in the format specified by the -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 M-bM-^@M-^\RFC4716M-bM-^@M-^]. + + -J num_lines + Exit after screening the specified number of lines while + performing DH candidate screening using the -T option. + + -j start_line + Start screening at the specified line number while performing DH + candidate screening using the -T option. + + -K checkpt + Write the last line processed to the file checkpt while + performing DH candidate screening using the -T option. This will + be used to skip lines in the input file that have already been + processed if the job is restarted. + + -k Generate a KRL file. In this mode, ssh-keygen will generate a + KRL file at the location specified via the -f flag that revokes + every key or certificate presented on the command line. + Keys/certificates to be revoked may be specified by public key + file or using the format described in the KEY REVOCATION LISTS + section. + + -L Prints the contents of one or more certificates. + + -l Show fingerprint of specified public key file. For RSA and DSA + keys ssh-keygen tries to find the matching public key file and + prints its fingerprint. If combined with -v, a visual ASCII art + representation of the key is supplied with the fingerprint. + + -M memory + Specify the amount of memory to use (in megabytes) when + generating candidate moduli for DH-GEX. + + -m key_format + Specify a key format for the -i (import) or -e (export) + conversion options. The supported key formats are: M-bM-^@M-^\RFC4716M-bM-^@M-^] + (RFC 4716/SSH2 public or private key), M-bM-^@M-^\PKCS8M-bM-^@M-^] (PEM PKCS8 public + key) or M-bM-^@M-^\PEMM-bM-^@M-^] (PEM public key). The default conversion format is + M-bM-^@M-^\RFC4716M-bM-^@M-^]. Setting a format of M-bM-^@M-^\PEMM-bM-^@M-^] when generating or updating + a supported private key type will cause the key to be stored in + the legacy PEM private key format. + + -N new_passphrase + Provides the new passphrase. + + -n 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 + CERTIFICATES section for details. + + -O option + Specify a certificate option when signing a key. This option may + be specified multiple times. See also the CERTIFICATES section + for further details. + + At present, no standard options are valid for host keys. The + options that are valid for user certificates are: + + clear Clear all enabled permissions. This is useful for + clearing the default set of permissions so permissions + may be added individually. + + critical:name[=contents] + extension:name[=contents] + Includes an arbitrary certificate critical option or + extension. The specified name should include a domain + suffix, e.g. M-bM-^@M-^\name@example.comM-bM-^@M-^]. If contents is + specified then it is included as the contents of the + extension/option encoded as a string, otherwise the + extension/option is created with no contents (usually + indicating a flag). Extensions may be ignored by a + client or server that does not recognise them, whereas + unknown critical options will cause the certificate to be + refused. + + force-command=command + Forces the execution of command instead of any shell or + command specified by the user when the certificate is + used for authentication. + + no-agent-forwarding + Disable ssh-agent(1) forwarding (permitted by default). + + no-port-forwarding + Disable port forwarding (permitted by default). + + no-pty Disable PTY allocation (permitted by default). + + no-user-rc + Disable execution of ~/.ssh/rc by sshd(8) (permitted by + default). + + no-x11-forwarding + Disable X11 forwarding (permitted by default). + + permit-agent-forwarding + Allows ssh-agent(1) forwarding. + + permit-port-forwarding + Allows port forwarding. + + permit-pty + Allows PTY allocation. + + permit-user-rc + Allows execution of ~/.ssh/rc by sshd(8). + + permit-X11-forwarding + Allows X11 forwarding. + + source-address=address_list + Restrict the source addresses from which the certificate + is considered valid. The address_list is a comma- + separated list of one or more address/netmask pairs in + CIDR format. + + -P passphrase + Provides the (old) passphrase. + + -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. + + -Q Test whether keys have been revoked in a KRL. + + -q Silence ssh-keygen. + + -R hostname + Removes all keys belonging to hostname from a known_hosts file. + This option is useful to delete hashed hosts (see the -H option + above). + + -r hostname + Print the SSHFP fingerprint resource record named hostname for + the specified public key file. + + -S start + Specify start point (in hex) when generating candidate moduli for + DH-GEX. + + -s ca_key + Certify (sign) a public key using the specified CA key. Please + see the CERTIFICATES section for details. + + When generating a KRL, -s specifies a path to a CA public key + file used to revoke certificates directly by key ID or serial + number. See the KEY REVOCATION LISTS section for details. + + -T output_file + Test DH group exchange candidate primes (generated using the -G + option) for safety. + + -t dsa | ecdsa | ed25519 | rsa + Specifies the type of key to create. The possible values are + M-bM-^@M-^\dsaM-bM-^@M-^], M-bM-^@M-^\ecdsaM-bM-^@M-^], M-bM-^@M-^\ed25519M-bM-^@M-^], or M-bM-^@M-^\rsaM-bM-^@M-^]. + + -U When used in combination with -s, this option indicates that a CA + key resides in a ssh-agent(1). See the CERTIFICATES section for + more information. + + -u Update a KRL. When specified with -k, keys listed via the + command line are added to the existing KRL rather than a new KRL + being created. + + -V 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 the string M-bM-^@M-^\alwaysM-bM-^@M-^] to + indicate the certificate has no specified start time, a date in + YYYYMMDD format, a time in YYYYMMDDHHMM[SS] format, a relative + time (to the current time) consisting of a minus sign followed by + an interval in the format described in the TIME FORMATS section + of sshd_config(5). + + The end time may be specified as a YYYYMMDD date, a + YYYYMMDDHHMM[SS] time, a relative time starting with a plus + character or the string M-bM-^@M-^\foreverM-bM-^@M-^] to indicate that the + certificate has no expirty date. + + For example: M-bM-^@M-^\+52w1dM-bM-^@M-^] (valid from now to 52 weeks and one day + from now), M-bM-^@M-^\-4w:+4wM-bM-^@M-^] (valid from four weeks ago to four weeks + from now), M-bM-^@M-^\20100101123000:20110101123000M-bM-^@M-^] (valid from 12:30 PM, + January 1st, 2010 to 12:30 PM, January 1st, 2011), M-bM-^@M-^\-1d:20110101M-bM-^@M-^] + (valid from yesterday to midnight, January 1st, 2011). + M-bM-^@M-^\-1m:foreverM-bM-^@M-^] (valid from one minute ago and never expiring). + + -v Verbose mode. Causes ssh-keygen to print debugging messages + about its progress. This is helpful for debugging moduli + generation. Multiple -v options increase the verbosity. The + maximum is 3. + + -W generator + Specify desired generator when testing candidate moduli for DH- + GEX. + + -y This option will read a private OpenSSH format file and print an + OpenSSH public key to stdout. + + -z 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. + + When generating a KRL, the -z flag is used to specify a KRL + version number. + +MODULI GENERATION + ssh-keygen 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). + + Generation of primes is performed using the -G option. The desired + length of the primes may be specified by the -b option. For example: + + # ssh-keygen -G moduli-2048.candidates -b 2048 + + By default, the search for primes begins at a random point in the desired + length range. This may be overridden using the -S option, which + specifies a different start point (in hex). + + Once a set of candidates have been generated, they must be screened for + suitability. This may be performed using the -T option. In this mode + ssh-keygen will read candidates from standard input (or a file specified + using the -f option). For example: + + # ssh-keygen -T moduli-2048 -f moduli-2048.candidates + + By default, each candidate will be subjected to 100 primality tests. + This may be overridden using the -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 -W option. Valid + generator values are 2, 3, and 5. + + Screened DH groups may be installed in /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. + +CERTIFICATES + ssh-keygen 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 ssl(8). + + ssh-keygen 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: + + $ ssh-keygen -s /path/to/ca_key -I key_id /path/to/user_key.pub + + The resultant certificate will be placed in /path/to/user_key-cert.pub. + A host certificate requires the -h option: + + $ ssh-keygen -s /path/to/ca_key -I key_id -h /path/to/host_key.pub + + The host certificate will be output to /path/to/host_key-cert.pub. + + It is possible to sign using a CA key stored in a PKCS#11 token by + providing the token library using -D and identifying the CA key by + providing its public half as an argument to -s: + + $ ssh-keygen -s ca_key.pub -D libpkcs11.so -I key_id user_key.pub + + Similarly, it is possible for the CA key to be hosted in a ssh-agent(1). + This is indicated by the -U flag and, again, the CA key must be + identified by its public half. + + $ ssh-keygen -Us ca_key.pub -I key_id user_key.pub + + In all cases, key_id is a "key identifier" that is logged by the server + when the certificate is used for authentication. + + 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: + + $ ssh-keygen -s ca_key -I key_id -n user1,user2 user_key.pub + $ ssh-keygen -s ca_key -I key_id -h -n host.domain host_key.pub + + 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 -O option above. + + Finally, certificates may be defined with a validity lifetime. The -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 are valid from UNIX Epoch to + the distant future. + + For certificates to be used for user or host authentication, the CA + public key must be trusted by sshd(8) or ssh(1). Please refer to those + manual pages for details. + +KEY REVOCATION LISTS + ssh-keygen is able to manage OpenSSH format Key Revocation Lists (KRLs). + These binary files specify keys or certificates to be revoked using a + compact format, taking as little as one bit per certificate if they are + being revoked by serial number. + + KRLs may be generated using the -k flag. This option reads one or more + files from the command line and generates a new KRL. The files may + either contain a KRL specification (see below) or public keys, listed one + per line. Plain public keys are revoked by listing their hash or + contents in the KRL and certificates revoked by serial number or key ID + (if the serial is zero or not available). + + Revoking keys using a KRL specification offers explicit control over the + types of record used to revoke keys and may be used to directly revoke + certificates by serial number or key ID without having the complete + original certificate on hand. A KRL specification consists of lines + containing one of the following directives followed by a colon and some + directive-specific information. + + serial: serial_number[-serial_number] + Revokes a certificate with the specified serial number. Serial + numbers are 64-bit values, not including zero and may be + expressed in decimal, hex or octal. If two serial numbers are + specified separated by a hyphen, then the range of serial numbers + including and between each is revoked. The CA key must have been + specified on the ssh-keygen command line using the -s option. + + id: key_id + Revokes a certificate with the specified key ID string. The CA + key must have been specified on the ssh-keygen command line using + the -s option. + + key: public_key + Revokes the specified key. If a certificate is listed, then it + is revoked as a plain public key. + + sha1: public_key + Revokes the specified key by including its SHA1 hash in the KRL. + + sha256: public_key + Revokes the specified key by including its SHA256 hash in the + KRL. KRLs that revoke keys by SHA256 hash are not supported by + OpenSSH versions prior to 7.9. + + hash: fingerprint + Revokes a key using a fingerprint hash, as obtained from a + sshd(8) authentication log message or the ssh-keygen -l flag. + Only SHA256 fingerprints are supported here and resultant KRLs + are not supported by OpenSSH versions prior to 7.9. + + KRLs may be updated using the -u flag in addition to -k. When this + option is specified, keys listed via the command line are merged into the + KRL, adding to those already there. + + It is also possible, given a KRL, to test whether it revokes a particular + key (or keys). The -Q flag will query an existing KRL, testing each key + specified on the command line. If any key listed on the command line has + been revoked (or an error encountered) then ssh-keygen will exit with a + non-zero exit status. A zero exit status will only be returned if no key + was revoked. + +FILES + ~/.ssh/id_dsa + ~/.ssh/id_ecdsa + ~/.ssh/id_ed25519 + ~/.ssh/id_rsa + Contains the DSA, ECDSA, Ed25519 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 ssh-keygen but it is offered as the default file for + the private key. ssh(1) will read this file when a login attempt + is made. + + ~/.ssh/id_dsa.pub + ~/.ssh/id_ecdsa.pub + ~/.ssh/id_ed25519.pub + ~/.ssh/id_rsa.pub + Contains the DSA, ECDSA, Ed25519 or RSA public key for + authentication. The contents of this file should be added to + ~/.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. + + /etc/moduli + Contains Diffie-Hellman groups used for DH-GEX. The file format + is described in moduli(5). + +SEE ALSO + ssh(1), ssh-add(1), ssh-agent(1), moduli(5), sshd(8) + + The Secure Shell (SSH) Public Key File Format, RFC 4716, 2006. + +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. + +OpenBSD 6.4 September 12, 2018 OpenBSD 6.4 |