4.14. dnssec-keygen --- DNSKEY and KEY generator¶
dnssec-keygen [-a <algorithm>] [-b <key-size>] [-n name-type] [-A date/offset] [-c class] [-D date/offset] [-E <engine-name>] [-f flag] [-G] [-g generator] [-h] [-I date/offset] [-i interval] [-K directory] [-L <ttl>] [-P date/offset] [-p protocol] [-q] [-R date/offset] [-S key] [-s strength] [-T <rrtype>] [-t type] [-v level] [-V] [-z] <name>
dnssec-keygen generates keys for DNSSEC (Secure DNS), as defined in RFC 2535 and RFC 4034. It can also generate keys for use with TSIG (Transaction Signatures) as defined in RFC 2845, or TKEY (Transaction Key) as defined in RFC 2930.
Selects the cryptographic algorithm. For DNSSEC keys, the value of <algorithm> must be one of RSASHA1, NSEC3RSASHA1, RSASHA256, RSASHA512, ECDSAP256SHA256, ECDSAP384SHA384, ED25519 or ED448. For TSIG/TKEY, the value must be DH (Diffie Hellman), HMAC-MD5, HMAC-SHA1, HMAC-SHA224, HMAC-SHA256, HMAC-SHA384, or HMAC-SHA512. These values are case-insensitive.
If no algorithm is specified, then ECDSAP256SHA256 will be used by default.
DH, HMAC-MD5, HMAC-SHA1, HMAC-SHA224, HMAC-SHA256, HMAC-SHA384, and HMAC-SHA512 automatically set the
Specifies the number of bits in the key. The choice of key size depends on the algorithm used. RSA keys must be between 512 and 4096 bits. Diffie Hellman keys must be between 128 and 4096 bits. HMAC keys must be between 1 and 512 bits. Elliptic curve algorithms don't need this parameter.
The key size does not need to be specified if using the default algorithm. However, if an algorithm is explicitly specified with the
-aoption, then there may be no default key size, and the
-boption should be used.
Specifies the owner type of the key. The value of <name-type> must either be ZONE (for a DNSSEC zone key (KEY/DNSKEY)), HOST or ENTITY (for a key associated with a host (KEY)), USER (for a key associated with a user(KEY)) or OTHER (DNSKEY). These values are case-insensitive. Defaults to ZONE for DNSKEY generation.
Indicates that the DNS record containing the key should have the specified class. If not specified, class IN is used.
Specifies the OpenSSL engine to use for cryptographic operations, such as a secure key store used for signing.
If generating a Diffie Hellman key, use this generator. Allowed <generator> values are 2 and 5. If no generator is specified, a known prime from RFC 2539 will be used if possible; otherwise the default is 2.
Sets the directory in which the key files are to be written.
Sets the default TTL to use for this key when it is converted into a DNSKEY RR. If the key is imported into a zone, this is the TTL that will be used for it, unless there was already a DNSKEY RRset in place, in which case the existing TTL would take precedence. If this value is not set and there is no existing DNSKEY RRset, the TTL will default to the SOA TTL. Setting the default TTL to 0 or none is the same as leaving it unset.
Sets the protocol value for the key. The protocol is a number between 0 and 255. The default is 3 (DNSSEC). Other possible values for this argument are listed in RFC 2535 and its successors.
Quiet mode: Suppresses unnecessary output, including progress indication. Without this option, when dnssec-keygen is run interactively to generate an RSA or DSA key pair, it will print a string of symbols to standard-error indicating the progress of the key generation. A dot(.) indicates that a random number has been found which passed an initial sieve test; plus(+) means a number has passed a single round of the Miller-Rabin primality test; a space means that the number has passed all the tests and is a satisfactory key.
Create a new key as an explicit successor to an existing key. The name, algorithm, size, and type of the key will be set to match the existing key. The activation date of the new key will be set to the inactivation date of the existing one. The publication date will be set to the activation date minus the pre-publication interval, which defaults to 30 days.
Specifies the strength value of the key. The strength is a number between 0 and 15, and currently has no defined purpose in DNSSEC.
Specifies the resource record type to use for the key. <rrtype> must be either DNSKEY or KEY. The default is DNSKEY when using a DNSSEC algorithm, but it can be overridden to KEY for use with SIG(0).
Using any TSIG algorithm (HMAC-* or DH) forces this option to KEY.
Indicates the use of the key. <type> must be one of AUTHCONF, NOAUTHCONF, NOAUTH, or NOCONF. The default is AUTHCONF. AUTH refers to the ability to authenticate data, and CONF the ability to encrypt data.
Print program usage information and exit.
Set the verbosity level.
Print the program's version and exit.
The name of the key. For DNSSEC keys, this must match the name of the zone for which the key is being generated.
4.14.4. Timing options¶
Dates can be expressed in the format YYYYMMDD or YYYYMMDDHHMMSS. If the argument begins with a + or -, it is interpreted as an offset from the present time. For convenience, if such an offset is followed by one of the suffixes y, mo, w, d, h, or mi, then the offset is computed in years (defined as 365 24-hour days, ignoring leap years), months (defined as 30 24-hour days), weeks, days, hours, or minutes, respectively. Without a suffix, the offset is computed in seconds. To explicitly prevent a date from being set, use none or never.
Sets the date on which a key is to be published to the zone. After that date, the key will be included in the zone but will not be used to sign it. If not set, and if the
-Goption has not been used, the default is now.
Sets the date on which the key is to be deleted. After that date, the key will no longer be included in the zone. (It may remain in the key repository, however.)
Sets the date on which the key is to be activated. After that date, the key will be included in the zone and used to sign it. If not set, and if the
-Goption has not been used, the default is now. If set, and if
-Pis not set, then the publication date will be set to the activation date minus the prepublication interval.
Sets the date on which the key is to be revoked. After that date, the key will be flagged as revoked. It will be included in the zone and will be used to sign it.
Sets the date on which the key is to be retired. After that date, the key will still be included in the zone, but it will not be used to sign it.
Sets the pre-publication interval for a key. If set, then the publication and activation dates must be separated by at least this much time. If the activation date is specified but the publication date isn't, then the publication date will default to this much time before the activation date; conversely, if the publication date is specified but activation date isn't, then activation will be set to this much time after publication.
If the key is being created as an explicit successor to another key, then the default prepublication interval is 30 days; otherwise it is zero.
As with date offsets, if the argument is followed by one of the suffixes y, mo, w, d, h, or mi, then the interval is measured in years, months, weeks, days, hours, or minutes, respectively. Without a suffix, the interval is measured in seconds.
4.14.5. Generated key files¶
When dnssec-keyfromlabel completes successfully, it prints a string of the form Knnnn.+aaa+iiiii to the standard output. This is an identification string for the key files it has generated.
<nnnn> is the key name.
<aaa> is the numeric representation of the algorithm.
<iiiii> is the key identifier (or footprint).
dnssec-keyfromlabel creates two files, with names based on the printed string. Knnnn.+aaa+iiiii.key contains the public key, and Knnnn.+aaa+iiiii.private contains the private key.
The .key file contains a DNSKEY record that can be inserted into a zone file (directly or with a $INCLUDE statement).
The .private file contains algorithm-specific fields. For obvious security reasons, this file does not have general read permission.
Both .key and .private files are generated even for symmetric cryptography algorithms such as HMAC-MD5, even though the public and private key are equivalent.
To generate a DNSKEY for the domain example.com, the following command would be issued:
[muks@naina ~]$ dnssec-keygen example.com Generating key pair. Kexample.com.+013+32634 [muks@naina ~]$
The command would print a string of the form:
In this example, dnssec-keygen creates the files
Kexample.com.+013+32634.private, containing a key of the default
ECDSAP256SHA256 algorithm type.
4.14.7. See also¶
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