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Commands Reference, Volume 2
dnssec-keygen Command
Purpose
DNSSEC key generation tool.
Syntax
dnssec-keygen [ -a algorithm ] [ -b keysize ] [ -n nametype ] [-c class ] [ -e ] [-g generator ] [ -h ] [ -p protocol ] [ -r randomdev ] [ -s strength ] [ -t type ] [ -v level ] [ name ]
Description
The dnssec-keygen command generates keys for DNSSEC
(Secure DNS), as defined in RFC 2535. It can also generate keys for use with
TSIG (Transaction Signatures), as defined in RFC 2845.
Flags
-a algorithm |
Selects the cryptographic algorithm. The value of algorithm
must be one of RSAMD5 or RSA, DSA, DH (Diffie Hellman), or HMAC-MD5. These
values are case insensitive. Note that for DNSSEC, DSA is a mandatory to
implement algorithm, and RSA is recommended. For TSIG, HMAC-MD5 is mandatory. |
-b keysize |
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
2048 bits. Diffie Hellman keys must be between 128 and 4096 bits. DSA keys
must be between 512 and 1024 bits and an exact multiple of 64. HMAC-MD5 keys
must be between 1 and 512 bits. |
-n nametype |
Specifies the owner type of the key. The value of nametype
must either be ZONE (for a DNSSEC zone key), HOST or ENTITY (for a key associated
with a host), or USER (for a key associated with a user). These values are
case insensitive. |
-c class |
Indicates that the DNS record containing the key should
have the specified class. If not specified, class IN is used. |
-e |
If generating an RSA key, use a large exponent. |
-g generator |
If generating a Diffie Hellman key, use this generator.
Allowed 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. |
-h |
Prints a short summary of the options and arguments
to dnssec-keygen. |
-p protocol |
Sets the protocol value for the generated key. The
protocol is a number between 0 and 255. The default is 2 (email) for keys
of type USER and 3 (DNSSEC) for all other key types. Other possible values
for this argument are listed in RFC 2535 and its successors. |
-r randomdev |
Specifies the source of randomness. If the operating
system does not provide a /dev/random or equivalent
device, the default source of randomness is keyboard input. randomdev specifies
the name of a character device or file containing random data to be used instead
of the default. The special value keyboard indicates that keyboard input should
be used. |
-s strength |
Specifies the strength value of the key. The strength
is a number between 0 and 15, and currently has no defined purpose in DNSSEC. |
-t type |
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. |
-v level |
Sets the debugging level. |
Generated Keys
When dnssec-keygen completes successfully, it prints
a string of the form Knnnn.+aaa+iiiii to
the standard output. This is an identification string for the key it has generated.
These strings can be used as arguments to dnssec-makekeyset.
- nnnn is the key name.
- aaa is the numeric representation of
the algorithm.
- iiiii is the key identifier (or footprint).
dnssec-keygen 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 DNS KEY
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 for symmetric encryption algorithm such as HMAC-MD5,
even though the public and private key are equivalent.
Examples
To generate a 768-bit DSA key for the domain example.com, the following
command would be issued:
dnssec-keygen -a DSA -b 768 -n ZONE example.com
The command would print a string of the form:
Kexample.com.+003+26160
In this example, dnssec-keygen creates the files Kexample.com.+003+26160.key and Kexample.com.+003+26160.private.
Related Information
The dnssec-makekeyset, dnssec-signkey, and dnssec-signzone, commands
The BIND 9 Administrator Reference Manual.
RFC 2535, RFC 2845, and RFC 2539.
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