DNSSEC-SIGNZONE(1) BIND 9 DNSSEC-SIGNZONE(1)

NAME

dnssec-signzone - DNSSEC zone signing tool

SYNOPSIS

dnssec-signzone [-a] [-c class] [-d directory] [-D] [-E engine] [-e
end-time] [-f output-file] [-g] [-h] [-i interval] [-I input-format]
[-j jitter] [-K directory] [-k key] [-L serial] [-M maxttl] [-N
soa-serial-format] [-o origin] [-O output-format] [-P] [-Q] [-q] [-R]
[-S] [-s start-time] [-T ttl] [-t] [-u] [-v level] [-V] [-X extended
end-time] [-x] [-z] [-3 salt] [-H iterations] [-A] {zonefile}
[key...]

DESCRIPTION

dnssec-signzone signs a zone; it generates NSEC and RRSIG records and
produces a signed version of the zone. The security status of
delegations from the signed zone (that is, whether the child zones
are secure) is determined by the presence or absence of a keyset file
for each child zone.

OPTIONS

-a This option verifies all generated signatures.

-c class
This option specifies the DNS class of the zone.

-C This option sets compatibility mode, in which a
keyset-zonename file is generated in addition to
dsset-zonename when signing a zone, for use by older versions
of dnssec-signzone.

-d directory
This option indicates the directory where BIND 9 should look
for dsset- or keyset- files.

-D This option indicates that only those record types
automatically managed by dnssec-signzone, i.e., RRSIG, NSEC,
NSEC3 and NSEC3PARAM records, should be included in the
output. If smart signing (-S) is used, DNSKEY records are
also included. The resulting file can be included in the
original zone file with $INCLUDE. This option cannot be
combined with -O raw or serial-number updating.

-E engine
This option specifies the hardware to use for cryptographic
operations, such as a secure key store used for signing, when
applicable.

When BIND 9 is built with OpenSSL, this needs to be set to the
OpenSSL engine identifier that drives the cryptographic
accelerator or hardware service module (usually pkcs11).

-g This option indicates that DS records for child zones should
be generated from a dsset- or keyset- file. Existing DS
records are removed.

-K directory
This option specifies the directory to search for DNSSEC keys.
If not specified, it defaults to the current directory.

-k key This option tells BIND 9 to treat the specified key as a
key-signing key, ignoring any key flags. This option may be
specified multiple times.

-M maxttl
This option sets the maximum TTL for the signed zone. Any TTL
higher than maxttl in the input zone is reduced to maxttl in
the output. This provides certainty as to the largest possible
TTL in the signed zone, which is useful to know when rolling
keys. The maxttl is the longest possible time before
signatures that have been retrieved by resolvers expire from
resolver caches. Zones that are signed with this option should
be configured to use a matching max-zone-ttl in named.conf.
(Note: This option is incompatible with -D, because it
modifies non-DNSSEC data in the output zone.)

-s start-time
This option specifies the date and time when the generated
RRSIG records become valid. This can be either an absolute or
relative time. An absolute start time is indicated by a number
in YYYYMMDDHHMMSS notation; 20000530144500 denotes 14:45:00
UTC on May 30th, 2000. A relative start time is indicated by
+N, which is N seconds from the current time. If no start-time
is specified, the current time minus 1 hour (to allow for
clock skew) is used.

-e end-time
This option specifies the date and time when the generated
RRSIG records expire. As with start-time, an absolute time is
indicated in YYYYMMDDHHMMSS notation. A time relative to the
start time is indicated with +N, which is N seconds from the
start time. A time relative to the current time is indicated
with now+N. If no end-time is specified, 30 days from the
start time is the default. end-time must be later than
start-time.

-X extended end-time
This option specifies the date and time when the generated
RRSIG records for the DNSKEY RRset expire. This is to be used
in cases when the DNSKEY signatures need to persist longer
than signatures on other records; e.g., when the private
component of the KSK is kept offline and the KSK signature is
to be refreshed manually.

As with end-time, an absolute time is indicated in
YYYYMMDDHHMMSS notation. A time relative to the start time is
indicated with +N, which is N seconds from the start time. A
time relative to the current time is indicated with now+N. If
no extended end-time is specified, the value of end-time is
used as the default. (end-time, in turn, defaults to 30 days
from the start time.) extended end-time must be later than
start-time.

-f output-file
This option indicates the name of the output file containing
the signed zone. The default is to append .signed to the input
filename. If output-file is set to -, then the signed zone is
written to the standard output, with a default output format
of full.

-h This option prints a short summary of the options and
arguments to dnssec-signzone.

-V This option prints version information.

-i interval
This option indicates that, when a previously signed zone is
passed as input, records may be re-signed. The interval option
specifies the cycle interval as an offset from the current
time, in seconds. If a RRSIG record expires after the cycle
interval, it is retained; otherwise, it is considered to be
expiring soon and it is replaced.

The default cycle interval is one quarter of the difference
between the signature end and start times. So if neither
end-time nor start-time is specified, dnssec-signzone
generates signatures that are valid for 30 days, with a cycle
interval of 7.5 days. Therefore, if any existing RRSIG records
are due to expire in less than 7.5 days, they are replaced.

Note that the calculation of cycle interval is based upon the
validity period of the replacement signatures that would be
generated by dnssec-signzone, not on the valid lifetimes of
the input RRSIGs being considered for pre-expiry replacement.

-I input-format
This option sets the format of the input zone file. Possible
formats are text (the default), and raw. This option is
primarily intended to be used for dynamic signed zones, so
that the dumped zone file in a non-text format containing
updates can be signed directly. This option is not useful for
non-dynamic zones.

-j jitter
When signing a zone with a fixed signature lifetime, all RRSIG
records issued at the time of signing expire simultaneously.
If the zone is incrementally signed, i.e., a previously signed
zone is passed as input to the signer, all expired signatures
must be regenerated at approximately the same time. The jitter
option specifies a jitter window that is used to randomize the
signature expire time, thus spreading incremental signature
regeneration over time.

Signature lifetime jitter also, to some extent, benefits
validators and servers by spreading out cache expiration,
i.e., if large numbers of RRSIGs do not expire at the same
time from all caches, there is less congestion than if all
validators need to refetch at around the same time.

-L serial
When writing a signed zone to "raw" format, this option sets
the "source serial" value in the header to the specified
serial number. (This is expected to be used primarily for
testing purposes.)

-n ncpus
This option specifies the number of threads to use. By
default, one thread is started for each detected CPU.

-N soa-serial-format
This option sets the SOA serial number format of the signed
zone. Possible formats are keep (the default), increment,
unixtime, and date.

keep This format indicates that the SOA serial number should
not be modified.

increment
This format increments the SOA serial number using RFC
1982 arithmetic.

unixtime
This format sets the SOA serial number to the number of
seconds since the beginning of the Unix epoch, unless
the serial number is already greater than or equal to
that value, in which case it is simply incremented by
one.

date This format sets the SOA serial number to today's date,
in YYYYMMDDNN format, unless the serial number is
already greater than or equal to that value, in which
case it is simply incremented by one.

-o origin
This option sets the zone origin. If not specified, the name
of the zone file is assumed to be the origin.

-O output-format
This option sets the format of the output file containing the
signed zone. Possible formats are text (the default), which is
the standard textual representation of the zone; full, which
is text output in a format suitable for processing by external
scripts; and raw and raw=N, which store the zone in binary
formats for rapid loading by named. raw=N specifies the format
version of the raw zone file: if N is 0, the raw file can be
read by any version of named; if N is 1, the file can be read
by release 9.9.0 or higher. The default is 1.

-P This option disables post-sign verification tests.

The post-sign verification tests ensure that for each
algorithm in use there is at least one non-revoked self-signed
KSK key, that all revoked KSK keys are self-signed, and that
all records in the zone are signed by the algorithm. This
option skips these tests.

-Q This option removes signatures from keys that are no longer
active.

Normally, when a previously signed zone is passed as input to
the signer, and a DNSKEY record has been removed and replaced
with a new one, signatures from the old key that are still
within their validity period are retained. This allows the
zone to continue to validate with cached copies of the old
DNSKEY RRset. The -Q option forces dnssec-signzone to remove
signatures from keys that are no longer active. This enables
ZSK rollover using the procedure described in RFC 6781 Section
4.1.1.1 ("Pre-Publish Zone Signing Key Rollover").

-q This option enables quiet mode, which suppresses unnecessary
output. Without this option, when dnssec-signzone is run it
prints three pieces of information to standard output: the
number of keys in use; the algorithms used to verify the zone
was signed correctly and other status information; and the
filename containing the signed zone. With the option that
output is suppressed, leaving only the filename.

-R This option removes signatures from keys that are no longer
published.

This option is similar to -Q, except it forces dnssec-signzone
to remove signatures from keys that are no longer published.
This enables ZSK rollover using the procedure described in RFC
6781 Section 4.1.1.2 ("Double Signature Zone Signing Key
Rollover").

-S This option enables smart signing, which instructs
dnssec-signzone to search the key repository for keys that
match the zone being signed, and to include them in the zone
if appropriate.

When a key is found, its timing metadata is examined to
determine how it should be used, according to the following
rules. Each successive rule takes priority over the prior
ones:
If no timing metadata has been set for the key, the key is
published in the zone and used to sign the zone.

If the key's publication date is set and is in the past,
the key is published in the zone.

If the key's activation date is set and is in the past, the
key is published (regardless of publication date) and used
to sign the zone.

If the key's revocation date is set and is in the past, and
the key is published, then the key is revoked, and the
revoked key is used to sign the zone.

If either the key's unpublication or deletion date is set
and in the past, the key is NOT published or used to sign
the zone, regardless of any other metadata.

If the key's sync publication date is set and is in the
past, synchronization records (type CDS and/or CDNSKEY) are
created.

If the key's sync deletion date is set and is in the past,
synchronization records (type CDS and/or CDNSKEY) are
removed.

-T ttl This option specifies a TTL to be used for new DNSKEY records
imported into the zone from the key repository. If not
specified, the default is the TTL value from the zone's SOA
record. This option is ignored when signing without -S, since
DNSKEY records are not imported from the key repository in
that case. It is also ignored if there are any pre-existing
DNSKEY records at the zone apex, in which case new records'
TTL values are set to match them, or if any of the imported
DNSKEY records had a default TTL value. In the event of a
conflict between TTL values in imported keys, the shortest one
is used.

-t This option prints statistics at completion.

-u This option updates the NSEC/NSEC3 chain when re-signing a
previously signed zone. With this option, a zone signed with
NSEC can be switched to NSEC3, or a zone signed with NSEC3 can
be switched to NSEC or to NSEC3 with different parameters.
Without this option, dnssec-signzone retains the existing
chain when re-signing.

-v level
This option sets the debugging level.

-x This option indicates that BIND 9 should only sign the DNSKEY,
CDNSKEY, and CDS RRsets with key-signing keys, and should omit
signatures from zone-signing keys. (This is similar to the
dnssec-dnskey-kskonly yes; zone option in named.)

-z This option indicates that BIND 9 should ignore the KSK flag
on keys when determining what to sign. This causes KSK-flagged
keys to sign all records, not just the DNSKEY RRset. (This is
similar to the update-check-ksk no; zone option in named.)

-3 salt
This option generates an NSEC3 chain with the given
hex-encoded salt. A dash (-) can be used to indicate that no
salt is to be used when generating the NSEC3 chain.

NOTE:
-3 - is the recommended configuration. Adding salt provides
no practical benefits. See RFC 9276.

-H iterations
This option indicates that, when generating an NSEC3 chain,
BIND 9 should use this many iterations. The default is 0.

WARNING:
Values greater than 0 cause interoperability issues and
also increase the risk of CPU-exhausting DoS attacks. See
RFC 9276.

-A This option indicates that, when generating an NSEC3 chain,
BIND 9 should set the OPTOUT flag on all NSEC3 records and
should not generate NSEC3 records for insecure delegations.

WARNING:
Do not use this option unless all its implications are
fully understood. This option is intended only for
extremely large zones (comparable to com.) with sparse
secure delegations. See RFC 9276.

-AA This option turns the OPTOUT flag off for all records. This is
useful when using the -u option to modify an NSEC3 chain which
previously had OPTOUT set.

zonefile
This option sets the file containing the zone to be signed.

key This option specifies which keys should be used to sign the
zone. If no keys are specified, the zone is examined for
DNSKEY records at the zone apex. If these records are found
and there are matching private keys in the current directory,
they are used for signing.

EXAMPLE

The following command signs the example.com zone with the
ECDSAP256SHA256 key generated by dnssec-keygen
(Kexample.com.+013+17247). Because the -S option is not being used,
the zone's keys must be in the master file (db.example.com). This
invocation looks for dsset files in the current directory, so that DS
records can be imported from them (-g).

% dnssec-signzone -g -o example.com db.example.com \
Kexample.com.+013+17247
db.example.com.signed
%

In the above example, dnssec-signzone creates the file
db.example.com.signed. This file should be referenced in a zone
statement in the named.conf file.

This example re-signs a previously signed zone with default
parameters. The private keys are assumed to be in the current
directory.

% cp db.example.com.signed db.example.com
% dnssec-signzone -o example.com db.example.com
db.example.com.signed
%

SEE ALSO

dnssec-keygen(8), BIND 9 Administrator Reference Manual, RFC 4033,
RFC 6781.

AUTHOR

Internet Systems Consortium

COPYRIGHT

2025, Internet Systems Consortium

9.18.34 2025-02-11 DNSSEC-SIGNZONE(1)