Configuration Reference¶
Description¶
Configuration files for Knot DNS use simplified YAML format. Simplified means that not all of the features are supported.
For the description of configuration items, we have to declare a meaning of the following symbols:
INT– IntegerSTR– Textual stringHEXSTR– Hexadecimal string (with0xprefix)BOOL– Boolean value (on/offortrue/false)TIME– Number of seconds, an integer with possible time multiplier suffix (s~ 1,m~ 60,h~ 3600 ord~ 24 * 3600)SIZE– Number of bytes, an integer with possible size multiplier suffix (B~ 1,K~ 1024,M~ 1024^2 orG~ 1024^3)BASE64– Base64 encoded stringADDR– IPv4 or IPv6 addressDNAME– Domain name...– Multi-valued item, order of the values is preserved[]– Optional value|– Choice
The configuration consists of several fixed sections and optional module sections. There are 16 fixed sections (module, server, xdp, control, log, statistics, database, keystore, key, remote, remotes, acl, submission, policy, template, zone). Module sections are prefixed with the mod- prefix (e.g. mod-stats).
Most of the sections (e.g. zone) are sequences of settings blocks. Each settings block begins with a unique identifier, which can be used as a reference from other sections (such an identifier must be defined in advance).
A multi-valued item can be specified either as a YAML sequence:
address: [10.0.0.1, 10.0.0.2]
or as more single-valued items each on an extra line:
address: 10.0.0.1
address: 10.0.0.2
If an item value contains spaces or other special characters, it is necessary to enclose such a value within double quotes " ".
If not specified otherwise, an item representing a file or a directory path may be defined either as an absolute path (starting with /), or a path relative to the same directory as the default value of the item.
Including configuration¶
Another configuration file or files, matching a pattern, can be included at the top level in the current file.
include: STR
include¶
A path or a matching pattern specifying one or more files that are included at the place of the include option position in the configuration. If the path is not absolute, then it is considered to be relative to the current file. The pattern can be an arbitrary string meeting POSIX glob requirements, e.g. dir/*.conf. Matching files are processed in sorted order.
Default: not set
module section¶
Dynamic modules loading configuration.
Note
If configured with non-empty --with-moduledir=path parameter, all shared modules in this directory will be automatically loaded.
module:
- id: STR
file: STR
id¶
A module identifier in the form of the mod- prefix and module name suffix.
file¶
A path to a shared library file with the module implementation.
Warning
If the path is not absolute, the library is searched in the set of system directories. See man dlopen for more details.
Default: ${libdir}/knot/modules-${version}/module_name.so (or ${path}/module_name.so if configured with --with-moduledir=path)
server section¶
General options related to the server.
server:
identity: [STR]
version: [STR]
nsid: [STR|HEXSTR]
rundir: STR
user: STR[:STR]
pidfile: STR
udp-workers: INT
tcp-workers: INT
background-workers: INT
async-start: BOOL
tcp-idle-timeout: TIME
tcp-io-timeout: INT
tcp-remote-io-timeout: INT
tcp-max-clients: INT
tcp-reuseport: BOOL
tcp-fastopen: BOOL
quic-max-clients: INT
quic-outbuf-max-size: SIZE
quic-idle-close-timeout: TIME
remote-pool-limit: INT
remote-pool-timeout: TIME
remote-retry-delay: TIME
socket-affinity: BOOL
udp-max-payload: SIZE
udp-max-payload-ipv4: SIZE
udp-max-payload-ipv6: SIZE
key-file: STR
cert-file: STR
edns-client-subnet: BOOL
answer-rotation: BOOL
automatic-acl: BOOL
proxy-allowlist: ADDR[/INT] | ADDR-ADDR ...
dbus-event: none | running | zone-updated | ksk-submission | dnssec-invalid ...
dbus-init-delay: TIME
listen: ADDR[@INT] ...
Caution
When you change configuration parameters dynamically or via configuration file reload, some parameters in the Server section require restarting the Knot server so that the changes take effect. See below for the details.
identity¶
An identity of the server returned in the response to the query for TXT record id.server. or hostname.bind. in the CHAOS class (RFC 4892). Set to an empty value to disable.
Default: FQDN hostname
version¶
A version of the server software returned in the response to the query for TXT record version.server. or version.bind. in the CHAOS class (RFC 4892). Set to an empty value to disable.
Default: server version
nsid¶
A DNS name server identifier (RFC 5001). Set to an empty value to disable.
Default: FQDN hostname at the moment of the daemon start
rundir¶
A path for storing run-time data (PID file, unix sockets, etc.). A non-absolute path is relative to the knotd startup directory.
Depending on the usage of this parameter, its change may require restart of the Knot server to take effect.
Default: ${localstatedir}/run/knot (configured with --with-rundir=path)
user¶
A system user with an optional system group (user:group) under which the server is run after starting and binding to interfaces. Linux capabilities are employed if supported.
Change of this parameter requires restart of the Knot server to take effect.
Default: root:root
pidfile¶
A PID file location.
Change of this parameter requires restart of the Knot server to take effect.
Default: rundir/knot.pid
udp-workers¶
A number of UDP workers (threads) used to process incoming queries over UDP.
Change of this parameter requires restart of the Knot server to take effect.
Default: equal to the number of online CPUs
tcp-workers¶
A number of TCP workers (threads) used to process incoming queries over TCP.
Change of this parameter requires restart of the Knot server to take effect.
Default: equal to the number of online CPUs, default value is at least 10
background-workers¶
A number of workers (threads) used to execute background operations (zone loading, zone updates, etc.).
Change of this parameter requires restart of the Knot server to take effect.
Default: equal to the number of online CPUs, default value is at most 10
async-start¶
If enabled, server doesn't wait for the zones to be loaded and starts responding immediately with SERVFAIL answers until the zone loads.
Default: off
tcp-idle-timeout¶
Maximum idle time (in seconds) between requests on an inbound TCP connection. It means if there is no activity on an inbound TCP connection during this limit, the connection is closed by the server.
Minimum: 1
Default: 10
tcp-io-timeout¶
Maximum time (in milliseconds) to receive or send one DNS message over an inbound TCP connection. It means this limit applies to normal DNS queries and replies, incoming DDNS, and outgoing zone transfers. The timeout is measured since some data is already available for processing. Set to 0 for infinity.
Default: 500 (milliseconds)
Caution
In order to reduce the risk of Slow Loris attacks, it's recommended setting this limit as low as possible on public servers.
tcp-remote-io-timeout¶
Maximum time (in milliseconds) to receive or send one DNS message over an outbound TCP connection which has already been established to a configured remote server. It means this limit applies to incoming zone transfers, sending NOTIFY, DDNS forwarding, and DS check or push. This timeout includes the time needed for a network round-trip and for a query processing by the remote. Set to 0 for infinity.
Default: 5000 (milliseconds)
tcp-reuseport¶
If enabled, each TCP worker listens on its own socket and the OS kernel socket load balancing is employed using SO_REUSEPORT (or SO_REUSEPORT_LB on FreeBSD). Due to the lack of one shared socket, the server can offer higher response rate processing over TCP. However, in the case of time-consuming requests (e.g. zone transfers of a TLD zone), enabled reuseport may result in delayed or not being responded client requests. So it is advisable to use this option on secondary servers.
Change of this parameter requires restart of the Knot server to take effect.
Default: off
tcp-fastopen¶
If enabled, use TCP Fast Open for outbound TCP communication (client side): incoming zone transfers, sending NOTIFY, and DDNS forwarding. This mode simplifies TCP handshake and can result in better networking performance. TCP Fast Open for inbound TCP communication (server side) isn't affected by this configuration as it's enabled automatically if supported by OS.
Note
The TCP Fast Open support must also be enabled on the OS level:
Linux/macOS: ensure kernel parameter
net.ipv4.tcp_fastopenis2or3for server side, and1or3for client side.FreeBSD: ensure kernel parameter
net.inet.tcp.fastopen.server_enableis1for server side, andnet.inet.tcp.fastopen.client_enableis1for client side.
Default: off
quic-max-clients¶
A maximum number of QUIC clients connected in parallel.
See also quic.
Change of this parameter requires restart of the Knot server to take effect.
Minimum: 128
Default: 10000 (ten thousand)
quic-outbuf-max-size¶
Maximum cumulative size of memory used for buffers of unACKed sent messages. This limit is per one UDP worker.
Note
Set low if little memory is available (together with quic-max-clients since QUIC connections are memory-heavy). Set to high value if outgoing zone transfers of big zone over QUIC are expected.
Change of this parameter requires restart of the Knot server to take effect.
Minimum: 1M (1 MiB)
Default: 100M (100 MiB)
quic-idle-close-timeout¶
Time in seconds, after which any idle QUIC connection is gracefully closed.
Change of this parameter requires restart of the Knot server to take effect.
Minimum: 1
Default: 4
remote-pool-limit¶
If nonzero, the server will keep up to this number of outgoing TCP connections open for later use. This is an optimization to avoid frequent opening of TCP connections to the same remote.
Change of this parameter requires restart of the Knot server to take effect.
Default: 0
remote-pool-timeout¶
The timeout in seconds after which the unused kept-open outgoing TCP connections to remote servers are closed.
Default: 5
remote-retry-delay¶
When a connection attempt times out to some remote address, this information will be kept for this specified time (in milliseconds) and other connections to the same address won't be attempted. This prevents repetitive waiting for timeout on an unreachable remote.
Default: 0
socket-affinity¶
If enabled and if SO_REUSEPORT is available on Linux, all configured network sockets are bound to UDP and TCP workers in order to increase the networking performance. This mode isn't recommended for setups where the number of network card queues is lower than the number of UDP or TCP workers.
Change of this parameter requires restart of the Knot server to take effect.
Default: off
tcp-max-clients¶
A maximum number of TCP clients connected in parallel, set this below the file descriptor limit to avoid resource exhaustion.
Note
It is advisable to adjust the maximum number of open files per process in your operating system configuration.
Default: one half of the file descriptor limit for the server process
udp-max-payload¶
Maximum EDNS0 UDP payload size default for both IPv4 and IPv6.
Default: 1232
udp-max-payload-ipv4¶
Maximum EDNS0 UDP payload size for IPv4.
Default: 1232
udp-max-payload-ipv6¶
Maximum EDNS0 UDP payload size for IPv6.
Default: 1232
key-file¶
Path to a server key PEM file which is used for DNS over QUIC communication. A non-absolute path of a user specified key file is relative to the @config_dir@ directory.
Change of this parameter requires restart of the Knot server to take effect.
Default: one-time in-memory key
cert-file¶
Path to a server certificate PEM file which is used for DNS over QUIC communication. A non-absolute path is relative to the @config_dir@ directory.
Change of this parameter requires restart of the Knot server to take effect.
Default: one-time in-memory certificate
edns-client-subnet¶
Enable or disable EDNS Client Subnet support. If enabled, responses to queries containing the EDNS Client Subnet option always contain a valid EDNS Client Subnet option according to RFC 7871.
Default: off
answer-rotation¶
Enable or disable sorted-rrset rotation in the answer section of normal replies. The rotation shift is simply determined by a query ID.
Default: off
automatic-acl¶
If enabled, automatic ACL setting of configured remotes is considered when evaluating authorized operations.
Default: off
proxy-allowlist¶
An ordered list of IP addresses, network subnets, or network ranges which are allowed as a source address of proxied DNS traffic over UDP. The supported proxy protocol is haproxy PROXY v2.
Note
TCP is not supported.
Default: not set
dbus-event¶
Specification of server or zone states which emit a D-Bus signal on the system bus. The bus name is cz.nic.knotd, the object path is /cz/nic/knotd, and the interface name is cz.nic.knotd.events.
Possible values:
none– No signal is emitted.running– There are two possible signals emitted:startedwhen the server is started and all configured zones (including catalog zones and their members) are loaded or successfully bootstrapped.stoppedwhen the server shutdown sequence is initiated.
zone-updated– The signalzone_updatedis emitted when a zone has been updated; the signal parameters are zone name and zone SOA serial.ksk-submission– The signalzone_ksk_submissionis emitted if there is a ready KSK present when the zone is signed; the signal parameters are zone name, KSK keytag, and KSK KASP id.dnssec-invalid– The signalzone_dnssec_invalidis emitted when DNSSEC validation fails; the signal parameter is zone name.
Note
This function requires systemd version at least 221.
Change of this parameter requires restart of the Knot server to take effect.
Default: none
dbus-init-delay¶
Time in seconds which the server waits upon D-Bus initialization to ensure the D-Bus client is ready to receive signals.
Change of this parameter requires restart of the Knot server to take effect.
Minimum: 0
Default: 1
listen¶
One or more IP addresses where the server listens for incoming queries. Optional port specification (default is 53) can be appended to each address using @ separator. Use 0.0.0.0 for all configured IPv4 addresses or :: for all configured IPv6 addresses. Filesystem path can be specified for listening on local unix SOCK_STREAM socket. Non-local address binding is automatically enabled if supported by the operating system.
Change of this parameter requires restart of the Knot server to take effect.
Default: not set
xdp section¶
Various options related to XDP listening, especially TCP.
xdp:
listen: STR[@INT] | ADDR[@INT] ...
udp: BOOL
tcp: BOOL
quic: BOOL
quic-port: INT
quic-log: BOOL
tcp-max-clients: INT
tcp-inbuf-max-size: SIZE
tcp-outbuf-max-size: SIZE
tcp-idle-close-timeout: TIME
tcp-idle-reset-timeout: TIME
tcp-resend-timeout: TIME
route-check: BOOL
Caution
When you change configuration parameters dynamically or via configuration file reload, some parameters in the XDP section require restarting the Knot server so that the changes take effect.
listen¶
One or more network device names (e.g. ens786f0) on which the Mode XDP is enabled. Alternatively, an IP address can be used instead of a device name, but the server will still listen on all addresses belonging to the same interface! Optional port specification (default is 53) can be appended to each device name or address using @ separator.
Change of this parameter requires restart of the Knot server to take effect.
Caution
If XDP workers only process regular DNS traffic over UDP, it is strongly recommended to also listen on the addresses which are intended to offer the DNS service, at least to fulfil the DNS requirement for working TCP.
Default: not set
udp¶
If enabled, DNS over UDP is processed with XDP workers.
Change of this parameter requires restart of the Knot server to take effect.
Default: on
tcp¶
If enabled, DNS over TCP traffic is processed with XDP workers.
The TCP stack limitations:
Congestion control is not implemented.
Lost packets that do not contain TCP payload may not be resend.
Not optimized for transfers of non-trivial zones.
Change of this parameter requires restart of the Knot server to take effect.
Default: off
quic¶
If enabled, DNS over QUIC is processed with XDP workers.
Change of this parameter requires restart of the Knot server to take effect.
Default: off
quic-port¶
DNS over QUIC will listen on the interfaces configured by listen, but on different port, configured by this option.
Change of this parameter requires restart of the Knot server to take effect.
Default: 853
quic-log¶
Triggers extensive logging of all QUIC protocol internals for every connection.
Change of this parameter requires restart of the Knot server to take effect.
Default: off
tcp-max-clients¶
A maximum number of TCP clients connected in parallel.
Minimum: 1024
Default: 1000000 (one million)
tcp-inbuf-max-size¶
Maximum cumulative size of memory used for buffers of incompletely received messages.
Minimum: 1M (1 MiB)
Default: 100M (100 MiB)
tcp-outbuf-max-size¶
Maximum cumulative size of memory used for buffers of unACKed sent messages.
Minimum: 1M (1 MiB)
Default: 100M (100 MiB)
tcp-idle-close-timeout¶
Time in seconds, after which any idle connection is gracefully closed.
Minimum: 1
Default: 10
tcp-idle-reset-timeout¶
Time in seconds, after which any idle connection is forcibly closed.
Minimum: 1
Default: 20
tcp-resend-timeout¶
Resend outgoing data packets (with DNS response payload) if not ACKed before this timeout.
Minimum: 1
Default: 5
route-check¶
If enabled, routing information from the operating system is considered when processing every incoming DNS packet received over the XDP interface:
If the outgoing interface of the corresponding DNS response differs from the incoming one, the packet is processed normally by UDP/TCP workers (XDP isn't used).
If the destination address is blackholed, unreachable, or prohibited, the DNS packet is dropped without any response.
The destination MAC address and possible VLAN tag for the response are taken from the routing system.
If disabled, symmetrical routing is applied. It means that the query source MAC address is used as a response destination MAC address. Possible VLAN tag is preserved.
Change of this parameter requires restart of the Knot server to take effect.
Note
This mode requires forwarding enabled on the loopback interface (sysctl -w net.ipv4.conf.lo.forwarding=1 and sysctl -w net.ipv6.conf.lo.forwarding=1). If forwarding is disabled, all incoming DNS packets are dropped!
Only VLAN 802.1Q is supported.
Default: off
control section¶
Configuration of the server control interface.
control:
listen: STR
timeout: TIME
listen¶
A UNIX socket path where the server listens for control commands.
Default: rundir/knot.sock
timeout¶
Maximum time (in seconds) the control socket operations can take. Set to 0 for infinity.
Default: 5
log section¶
Server can be configured to log to the standard output, standard error output, syslog (or systemd journal if systemd is enabled) or into an arbitrary file.
There are 6 logging severity levels:
critical– Non-recoverable error resulting in server shutdown.error– Recoverable error, action should be taken.warning– Warning that might require user action.notice– Server notice or hint.info– Informational message.debug– Debug or detailed message.
In the case of a missing log section, warning or more serious messages will be logged to both standard error output and syslog. The info and notice messages will be logged to standard output.
log:
- target: stdout | stderr | syslog | STR
server: critical | error | warning | notice | info | debug
control: critical | error | warning | notice | info | debug
zone: critical | error | warning | notice | info | debug
any: critical | error | warning | notice | info | debug
target¶
A logging output.
Possible values:
stdout– Standard output.stderr– Standard error output.syslog– Syslog or systemd journal.file_name – A specific file.
With syslog target, syslog service is used. However, if Knot DNS has been compiled with systemd support and operating system has been booted with systemd, systemd journal is used for logging instead of syslog.
A file_name may be specified as an absolute path or a path relative to the knotd startup directory.
server¶
Minimum severity level for messages related to general operation of the server to be logged.
Default: not set
control¶
Minimum severity level for messages related to server control to be logged.
Default: not set
zone¶
Minimum severity level for messages related to zones to be logged.
Default: not set
any¶
Minimum severity level for all message types to be logged.
Default: not set
stats section¶
Periodic server statistics dumping.
statistics:
timer: TIME
file: STR
append: BOOL
timer¶
A period after which all available statistics metrics will by written to the file.
Default: not set
file¶
A file path of statistics output in the YAML format.
Default: rundir/stats.yaml
append¶
If enabled, the output will be appended to the file instead of file replacement.
Default: off
database section¶
Configuration of databases for zone contents, DNSSEC metadata, or event timers.
database:
storage: STR
journal-db: STR
journal-db-mode: robust | asynchronous
journal-db-max-size: SIZE
kasp-db: STR
kasp-db-max-size: SIZE
timer-db: STR
timer-db-max-size: SIZE
catalog-db: str
catalog-db-max-size: SIZE
storage¶
A data directory for storing journal, KASP, and timer databases. A non-absolute path is relative to the knotd startup directory.
Default: ${localstatedir}/lib/knot (configured with --with-storage=path)
journal-db¶
An explicit specification of the persistent journal database directory.
Default: storage/journal
journal-db-mode¶
Specifies journal LMDB backend configuration, which influences performance and durability.
Possible values:
robust– The journal database disk synchronization ensures database durability but is generally slower.asynchronous– The journal database disk synchronization is optimized for better performance at the expense of lower database durability in the case of a crash. This mode is recommended on secondary servers with many zones.
Default: robust
journal-db-max-size¶
The hard limit for the journal database maximum size. There is no cleanup logic in journal to recover from reaching this limit. Journal simply starts refusing changes across all zones. Decreasing this value has no effect if it is lower than the actual database file size.
It is recommended to limit journal-max-usage per-zone instead of journal-db-max-size in most cases. Please keep this value larger than the sum of all zones' journal usage limits. See more details regarding journal behaviour.
Note
This value also influences server's usage of virtual memory.
Default: 20G (20 GiB), or 512M (512 MiB) for 32-bit
kasp-db¶
An explicit specification of the KASP database directory.
Default: storage/keys
kasp-db-max-size¶
The hard limit for the KASP database maximum size.
Note
This value also influences server's usage of virtual memory.
Default: 500M (500 MiB)
timer-db¶
An explicit specification of the persistent timer database directory.
Default: storage/timers
timer-db-max-size¶
The hard limit for the timer database maximum size.
Note
This value also influences server's usage of virtual memory.
Default: 100M (100 MiB)
catalog-db¶
An explicit specification of the zone catalog database directory. Only useful if Catalog zones are enabled.
Default: storage/catalog
catalog-db-max-size¶
The hard limit for the catalog database maximum size.
Note
This value also influences server's usage of virtual memory.
Default: 20G (20 GiB), or 512M (512 MiB) for 32-bit
keystore section¶
DNSSEC keystore configuration.
keystore:
- id: STR
backend: pem | pkcs11
config: STR
key-label: BOOL
id¶
A keystore identifier.
backend¶
A key storage backend type.
Possible values:
pem– PEM files.pkcs11– PKCS #11 storage.
Default: pem
config¶
A backend specific configuration. A directory with PEM files (the path can be specified as a relative path to kasp-db) or a configuration string for PKCS #11 storage (<pkcs11-uri> <module-path>). The PKCS #11 URI Scheme is defined in RFC 7512.
Note
Example configuration string for PKCS #11:
"pkcs11:token=knot;pin-value=1234 /usr/lib64/pkcs11/libsofthsm2.so"
Default: kasp-db/keys
key-label¶
If enabled in combination with the PKCS #11 backend, generated keys are labeled in the form <zone_name> KSK|ZSK.
Default: off
key section¶
Shared TSIG keys used to authenticate communication with the server.
key:
- id: DNAME
algorithm: hmac-md5 | hmac-sha1 | hmac-sha224 | hmac-sha256 | hmac-sha384 | hmac-sha512
secret: BASE64
id¶
A key name identifier.
Note
This value MUST be exactly the same as the name of the TSIG key on the opposite primary/secondary server(s).
algorithm¶
A TSIG key algorithm. See TSIG Algorithm Numbers.
Possible values:
hmac-md5hmac-sha1hmac-sha224hmac-sha256hmac-sha384hmac-sha512
Default: not set
secret¶
Shared key secret.
Default: not set
remote section¶
Definitions of remote servers for outgoing connections (source of a zone transfer, target for a notification, etc.).
remote:
- id: STR
address: ADDR[@INT] ...
via: ADDR[@INT] ...
key: key_id
block-notify-after-transfer: BOOL
no-edns: BOOL
automatic-acl: BOOL
id¶
A remote identifier.
address¶
An ordered list of destination IP addresses which are used for communication with the remote server. The addresses are tried in sequence until the remote is reached. Optional destination port (default is 53) can be appended to the address using @ separator.
Default: not set
Note
If the remote is contacted and it refuses to perform requested action, no more addresses will be tried for this remote.
via¶
An ordered list of source IP addresses. The first address with the same family as the destination address is used as a source address for communication with the remote. This option can help if the server listens on more addresses. Optional source port (default is random) can be appended to the address using @ separator.
Default: not set
key¶
A reference to the TSIG key which is used to authenticate the communication with the remote server.
Default: not set
block-notify-after-transfer¶
When incoming AXFR/IXFR from this remote (as a primary server), suppress sending NOTIFY messages to all configured secondary servers.
Default: off
no-edns¶
If enabled, no OPT record (EDNS) is inserted to outgoing requests to this remote server. This mode is necessary for communication with some broken implementations (e.g. Windows Server 2016).
Note
This option effectively disables zone expire timer updates via EDNS EXPIRE option specified in RFC 7314.
Default: off
automatic-acl¶
If enabled, some authorized operations for the remote are automatically allowed based on the context:
Incoming NOTIFY is allowed from the remote if it's configured as a primary server for the zone.
Outgoing zone transfer is allowed to the remote if it's configured as a NOTIFY target for the zone.
Automatic ACL rules are evaluated before explicit zone ACL configuration.
Note
This functionality requires global activation via automatic-acl in the server section.
Default: on
remotes section¶
Definitions of groups of remote servers. Remote grouping can simplify the configuration.
remotes:
- id: STR
remote: remote_id ...
id¶
A remote group identifier.
remote¶
An ordered list of references to remote server definitions.
Default: not set
acl section¶
Access control list rule definitions. An ACL rule is a description of one or more authorized operations (zone transfer request, zone change notification, and dynamic DNS update) which are allowed to be processed or denied.
acl:
- id: STR
address: ADDR[/INT] | ADDR-ADDR ...
key: key_id ...
remote: remote_id | remotes_id ...
action: query | notify | transfer | update ...
deny: BOOL
update-type: STR ...
update-owner: key | zone | name
update-owner-match: sub-or-equal | equal | sub
update-owner-name: STR ...
id¶
An ACL rule identifier.
address¶
An ordered list of IP addresses, network subnets, or network ranges. The query's source address must match one of them. If this item is not set, address match is not required.
Default: not set
key¶
An ordered list of references to TSIG keys. The query must match one of them. If this item is not set, transaction authentication is not used.
Default: not set
remote¶
An ordered list of references remote and remotes. The query must match one of the remotes. Specifically, one of the remote's addresses and remote's TSIG key if configured must match.
Default: not set
action¶
An ordered list of allowed (or denied) actions.
Possible values:
query– Allow regular DNS query. As normal queries are always allowed, this action is only useful in combination with TSIG key.notify– Allow incoming notify (NOTIFY).transfer– Allow zone transfer (AXFR, IXFR).update– Allow zone updates (DDNS).
Default: query
deny¶
If enabled, instead of allowing, deny the specified action, address, key, or combination if these items. If no action is specified, deny all actions.
Default: off
update-type¶
A list of allowed types of Resource Records in a zone update. Every record in an update must match one of the specified types.
Default: not set
update-owner¶
This option restricts possible owners of Resource Records in a zone update by comparing them to either the TSIG key identity, the current zone name, or to a list of domain names given by the update-owner-name option. The comparison method is given by the update-owner-match option.
Possible values:
key— The owner of each updated RR must match the identity of the TSIG key if used.name— The owner of each updated RR must match at least one name in the update-owner-name list.zone— The owner of each updated RR must match the current zone name.
Default: not set
update-owner-match¶
This option defines how the owners of Resource Records in an update are matched to the domain name(s) set by the update-owner option.
Possible values:
sub-or-equal— The owner of each RR in an update must either be equal to or be a subdomain of at least one domain name set by update-owner.equal— The owner of each updated RR must be equal to at least one domain name set by update-owner.sub— The owner of each updated RR must be a subdomain of, but MUST NOT be equal to at least one domain name set by update-owner.
Default: sub-or-equal
update-owner-name¶
A list of allowed owners of RRs in a zone update used with update-owner set to name. Every listed owner name which is not FQDN (i.e. it doesn't end in a dot) is considered as if it was appended with the target zone name. Such a relative owner name specification allows better ACL rule reusability across multiple zones.
Default: not set
submission section¶
Parameters of KSK submission checks.
submission:
- id: STR
parent: remote_id | remotes_id ...
check-interval: TIME
timeout: TIME
parent-delay: TIME
id¶
A submission identifier.
parent¶
A list of references remote and remotes to parent's DNS servers to be checked for presence of corresponding DS records in the case of KSK submission. All of them must have a corresponding DS for the rollover to continue. If none is specified, the rollover must be pushed forward manually.
Default: not set
Tip
A DNSSEC-validating resolver can be set as a parent.
check-interval¶
Interval for periodic checks of DS presence on parent's DNS servers, in the case of the KSK submission.
Default: 1h (1 hour)
timeout¶
After this time period (in seconds) the KSK submission is automatically considered successful, even if all the checks were negative or no parents are configured. Set to 0 for infinity.
Default: 0
parent-delay¶
After successful parent DS check, wait for this period before continuing the next key roll-over step. This delay shall cover the propagation delay of update in the parent zone.
Default: 0
policy section¶
DNSSEC policy configuration.
policy:
- id: STR
keystore: keystore_id
manual: BOOL
single-type-signing: BOOL
algorithm: rsasha1 | rsasha1-nsec3-sha1 | rsasha256 | rsasha512 | ecdsap256sha256 | ecdsap384sha384 | ed25519 | ed448
ksk-size: SIZE
zsk-size: SIZE
ksk-shared: BOOL
dnskey-ttl: TIME
zone-max-ttl: TIME
ksk-lifetime: TIME
zsk-lifetime: TIME
delete-delay: TIME
propagation-delay: TIME
rrsig-lifetime: TIME
rrsig-refresh: TIME
rrsig-pre-refresh: TIME
reproducible-signing: BOOL
nsec3: BOOL
nsec3-iterations: INT
nsec3-opt-out: BOOL
nsec3-salt-length: INT
nsec3-salt-lifetime: TIME
signing-threads: INT
ksk-submission: submission_id
ds-push: remote_id | remotes_id ...
cds-cdnskey-publish: none | delete-dnssec | rollover | always | double-ds
cds-digest-type: sha256 | sha384
dnskey-management: full | incremental
offline-ksk: BOOL
unsafe-operation: none | no-check-keyset | no-update-dnskey | no-update-nsec | no-update-expired ...
id¶
A policy identifier.
keystore¶
A reference to a keystore holding private key material for zones.
Default: an imaginary keystore with all default values
Note
A configured keystore called "default" won't be used unless explicitly referenced.
manual¶
If enabled, automatic key management is not used.
Default: off
single-type-signing¶
If enabled, Single-Type Signing Scheme is used in the automatic key management mode.
Default: off (module onlinesign has default on)
algorithm¶
An algorithm of signing keys and issued signatures. See DNSSEC Algorithm Numbers.
Possible values:
rsasha1rsasha1-nsec3-sha1rsasha256rsasha512ecdsap256sha256ecdsap384sha384ed25519ed448
Note
Ed25519 algorithm is only available if compiled with GnuTLS 3.6.0+.
Ed448 algorithm is only available if compiled with GnuTLS 3.6.12+ and Nettle 3.6+.
Default: ecdsap256sha256
ksk-size¶
A length of newly generated KSK or CSK keys.
Default: 2048 (rsa*), 256 (ecdsap256), 384 (ecdsap384), 256 (ed25519), 456 (ed448)
zsk-size¶
A length of newly generated ZSK keys.
Default: see default for ksk-size
dnskey-ttl¶
A TTL value for DNSKEY records added into zone apex.
Note
Has influence over ZSK key lifetime.
Warning
Ensure all DNSKEYs with updated TTL are propagated before any subsequent DNSKEY rollover starts.
Default: zone SOA TTL
zone-max-ttl¶
Declare (override) maximal TTL value among all the records in zone.
Note
It's generally recommended to override the maximal TTL computation by setting this explicitly whenever possible. It's required for DNSSEC Offline KSK and really reasonable when records are generated dynamically (e.g. by a module).
Default: computed after zone is loaded
ksk-lifetime¶
A period between KSK generation and the next rollover initiation.
Note
KSK key lifetime is also influenced by propagation-delay, dnskey-ttl, and KSK submission delay.
Zero (aka infinity) value causes no KSK rollover as a result.
This applies for CSK lifetime if single-type-signing is enabled.
Default: 0
zsk-lifetime¶
A period between ZSK activation and the next rollover initiation.
Note
More exactly, this period is measured since a ZSK is activated, and after this, a new ZSK is generated to replace it within following roll-over.
ZSK key lifetime is also influenced by propagation-delay and dnskey-ttl
Zero (aka infinity) value causes no ZSK rollover as a result.
Default: 30d (30 days)
delete-delay¶
Once a key (KSK or ZSK) is rolled-over and removed from the zone, keep it in the KASP database for at least this period before deleting it completely. This might be useful in some troubleshooting cases when resurrection is needed.
Default: 0
propagation-delay¶
An extra delay added for each key rollover step. This value should be high enough to cover propagation of data from the primary server to all secondary servers, as well as the duration of signing routine itself and possible outages in signing and propagation infrastructure. In other words, this delay should ensure that within this period of time after planned change of the key set, all public-facing secondaries will already serve new DNSKEY RRSet for sure.
Note
Has influence over ZSK key lifetime.
Default: 1h (1 hour)
rrsig-lifetime¶
A validity period of newly issued signatures.
Note
The RRSIG's signature inception time is set to 90 minutes in the past. This time period is not counted to the signature lifetime.
Default: 14d (14 days)
rrsig-refresh¶
A period how long at least before a signature expiration the signature will be refreshed, in order to prevent expired RRSIGs on secondary servers or resolvers' caches.
Default: propagation-delay + zone-max-ttl
rrsig-pre-refresh¶
A period how long at most before a signature refresh time the signature might be refreshed, in order to refresh RRSIGs in bigger batches on a frequently updated zone (avoid re-sign event too often).
Default: 1h (1 hour)
reproducible-signing¶
For ECDSA algorithms, generate RRSIG signatures deterministically (RFC 6979). Besides better theoretical cryptographic security, this mode allows significant speed-up of loading signed (by the same method) zones. However, the zone signing is a bit slower.
Default: off
nsec3¶
Specifies if NSEC3 will be used instead of NSEC.
Default: off
nsec3-iterations¶
A number of additional times the hashing is performed.
Default: 0
nsec3-opt-out¶
If set, NSEC3 records won't be created for insecure delegations. This speeds up the zone signing and reduces overall zone size.
Warning
NSEC3 with the Opt-Out bit set no longer works as a proof of non-existence in this zone.
Default: off
nsec3-salt-length¶
A length of a salt field in octets, which is appended to the original owner name before hashing.
Default: 8
nsec3-salt-lifetime¶
A validity period of newly issued salt field.
Zero value means infinity.
Special value -1 triggers re-salt every time when active ZSK changes. This optimizes the number of big changes to the zone.
Default: 30d (30 days)
signing-threads¶
When signing zone or update, use this number of threads for parallel signing.
Those are extra threads independent of Background workers.
Note
Some steps of the DNSSEC signing operation are not parallelized.
Default: 1 (no extra threads)
ksk-submission¶
A reference to submission section holding parameters of KSK submission checks.
Default: not set
ds-push¶
Optional references remote and remotes to authoritative DNS server of the parent's zone. The remote server must be configured to accept DS record updates via DDNS. Whenever a CDS record in the local zone is changed, the corresponding DS record is sent as a dynamic update (DDNS) to the parent DNS server. All previous DS records are deleted within the DDNS message. It's possible to manage both child and parent zones by the same Knot DNS server.
Note
This feature requires cds-cdnskey-publish not to be set to none.
Note
The mentioned change to CDS record usually means that a KSK roll-over is running and the new key being rolled-in is in "ready" state already for the period of propagation-delay.
Note
Module Onlinesign doesn't support DS push.
Default: not set
cds-cdnskey-publish¶
Controls if and how shall the CDS and CDNSKEY be published in the zone.
Possible values:
none– Never publish any CDS or CDNSKEY records in the zone.delete-dnssec– Publish special CDS and CDNSKEY records indicating turning off DNSSEC.rollover– Publish CDS and CDNSKEY records for ready and not yet active KSK (submission phase of KSK rollover).always– Always publish one CDS and one CDNSKEY records for the current KSK.double-ds– Always publish up to two CDS and two CDNSKEY records for ready and/or active KSKs.
Note
If the zone keys are managed manually, the CDS and CDNSKEY rrsets may contain more records depending on the keys available.
Warning
The double-ds value does not trigger double-DS roll-over method. That method is only supported when performed manually, with unset ksk-submission.
Default: rollover
cds-digest-type¶
Specify digest type for published CDS records.
Default: sha256
dnskey-management¶
Specify how the DNSKEY, CDNSKEY, and CDS RRSets at the zone apex are handled when (re-)signing the zone.
Possible values:
full– Upon every zone (re-)sign, delete all unknown DNSKEY, CDNSKEY, and CDS records and keep just those that are related to the zone keys stored in the KASP database.incremental– Keep unknown DNSKEY, CDNSKEY, and CDS records in the zone, and modify server-managed records incrementally by employing changes in the KASP database.
Note
Prerequisites for incremental:
The Offline KSK isn't supported.
The delete-delay is long enough to cover possible daemon shutdown (e.g. due to server maintenance).
Avoided manual deletion of keys with keymgr.
Otherwise there might remain some DNSKEY records in the zone, belonging to deleted keys.
Default: full
offline-ksk¶
Specifies if Offline KSK feature is enabled.
Default: off
unsafe-operation¶
Turn off some DNSSEC safety features.
Possible values:
none– Nothing disabled.no-check-keyset– Don't check active keys in present algorithms. This may lead to violation of RFC 4035#section-2.2.no-update-dnskey– Don't maintain/update DNSKEY, CDNSKEY, and CDS records in the zone apex according to KASP database. Juste leave them as they are in the zone.no-update-nsec– Don't maintain/update NSEC/NSEC3 chain. Leave all the records as they are in the zone.no-update-expired– Don't update expired RRSIGs.
Multiple values may be specified.
Warning
This mode is intended for DNSSEC experts who understand the corresponding consequences.
Default: none
template section¶
A template is shareable zone settings, which can simplify configuration by reducing duplicates. A special default template (with the default identifier) can be used for global zone configuration or as an implicit configuration if a zone doesn't have another template specified.
template:
- id: STR
global-module: STR/STR ...
# All zone options (excluding 'template' item)
Note
If an item is explicitly specified both in the referenced template and the zone, the template item value is overridden by the zone item value.
id¶
A template identifier.
global-module¶
An ordered list of references to query modules in the form of module_name or module_name/module_id. These modules apply to all queries.
Note
This option is only available in the default template.
Default: not set
zone section¶
Definition of zones served by the server.
zone:
- domain: DNAME
template: template_id
storage: STR
file: STR
master: remote_id | remotes_id ...
ddns-master: remote_id
notify: remote_id | remotes_id ...
acl: acl_id ...
provide-ixfr: BOOL
semantic-checks: BOOL | soft
zonefile-sync: TIME
zonefile-load: none | difference | difference-no-serial | whole
journal-content: none | changes | all
journal-max-usage: SIZE
journal-max-depth: INT
ixfr-by-one: BOOL
zone-max-size : SIZE
adjust-threads: INT
dnssec-signing: BOOL
dnssec-validation: BOOL
dnssec-policy: policy_id
ds-push: remote_id | remotes_id ...
zonemd-verify: BOOL
zonemd-generate: none | zonemd-sha384 | zonemd-sha512 | remove
serial-policy: increment | unixtime | dateserial
refresh-min-interval: TIME
refresh-max-interval: TIME
retry-min-interval: TIME
retry-max-interval: TIME
expire-min-interval: TIME
expire-max-interval: TIME
catalog-role: none | interpret | generate | member
catalog-template: template_id ...
catalog-zone: DNAME
catalog-group: STR
module: STR/STR ...
domain¶
A zone name identifier.
template¶
A reference to a configuration template.
Default: not set or default (if the template exists)
storage¶
A data directory for storing zone files. A non-absolute path is relative to the knotd startup directory.
Default: ${localstatedir}/lib/knot (configured with --with-storage=path)
file¶
A path to the zone file. It is also possible to use the following formatters:
%c[N]or%c[N-M]– Means the Nth character or a sequence of characters beginning from the Nth and ending with the Mth character of the textual zone name (see%s). The indexes are counted from 0 from the left. All dots (including the terminal one) are considered. If the character is not available, the formatter has no effect.%l[N]– Means the Nth label of the textual zone name (see%s). The index is counted from 0 from the right (0 ~ TLD). If the label is not available, the formatter has no effect.%s– Means the current zone name in the textual representation. The zone name doesn't include the terminating dot (the result for the root zone is the empty string!).%%– Means the%character.
Warning
Beware of special characters which are escaped or encoded in the \DDD form where DDD is corresponding decimal ASCII code.
Default: storage/%s.zone
master¶
An ordered list of references remote and remotes to zone primary servers (formerly known as master servers).
Default: not set
ddns-master¶
A reference to zone primary master. If not specified, the first master server is used.
Default: not set
notify¶
An ordered list of references remote and remotes to secondary servers to which notify message is sent if the zone changes.
Default: not set
acl¶
An ordered list of references to ACL rules which can allow or disallow zone transfers, updates or incoming notifies.
Default: not set
provide-ixfr¶
If disabled, the server is forced to respond with AXFR to IXFR queries. If enabled, IXFR requests are responded normally.
Default: on
semantic-checks¶
Selects if extra zone semantic checks are used or impacts of the mandatory checks.
There are several mandatory checks which are always enabled and cannot be turned off. An error in a mandatory check causes the zone not to be loaded. Most of the mandatory checks can be weakened by setting soft, which allows the zone to be loaded even if the check fails.
If enabled, extra checks are used. These checks don't prevent the zone from loading.
The mandatory checks are applied to zone files, zone transfers, and updates via control interface. The extra checks are applied to zone files only!
Mandatory checks:
Missing SOA record at the zone apex (RFC 1034) (*)
An extra record exists together with a CNAME record except for RRSIG and NSEC (RFC 1034)
Multiple CNAME records with the same owner exist (RFC 1034)
DNAME record having a record under it (RFC 6672)
Multiple DNAME records with the same owner exist (RFC 6672)
NS record exists together with a DNAME record (RFC 6672)
(*) The marked check can't be weakened by the soft mode. All other mandatory checks are subject to the optional soft mode.
Extra checks:
Missing NS record at the zone apex
Missing glue A or AAAA record
Invalid DS or NSEC3PARAM record
CDS or CDNSKEY inconsistency
All other DNSSEC checks executed during dnssec-validation
Note
The soft mode allows the refresh event to ignore a CNAME response to a SOA query (malformed message) and triggers a zone bootstrap instead.
Default: off
zonefile-sync¶
The time after which the current zone in memory will be synced with a zone file on the disk (see file). The server will serve the latest zone even after a restart using zone journal, but the zone file on the disk will only be synced after zonefile-sync time has expired (or after manual zone flush). This is applicable when the zone is updated via IXFR, DDNS or automatic DNSSEC signing. In order to completely disable automatic zone file synchronization, set the value to -1. In that case, it is still possible to force a manual zone flush using the -f option.
Note
If you are serving large zones with frequent updates where the immediate sync with a zone file is not desirable, increase the value.
Default: 0 (immediate)
zonefile-load¶
Selects how the zone file contents are applied during zone load.
Possible values:
none– The zone file is not used at all.difference– If the zone contents are already available during server start or reload, the difference is computed between them and the contents of the zone file. This difference is then checked for semantic errors and applied to the current zone contents.difference-no-serial– Same asdifference, but the SOA serial in the zone file is ignored, the server takes care of incrementing the serial automatically.whole– Zone contents are loaded from the zone file.
When difference is configured and there are no zone contents yet (cold start and no zone contents in the journal), it behaves the same way as whole.
Default: whole
Note
See Handling zone file, journal, changes, serials for guidance on configuring these and related options to ensure reliable operation.
journal-content¶
Selects how the journal shall be used to store zone and its changes.
Possible values:
none– The journal is not used at all.changes– Zone changes history is stored in journal.all– Zone contents and history is stored in journal.
Default: changes
Warning
When this option is changed, the journal still contains data respective to the previous setting. For example, changing it to none does not purge the journal. Also, changing it from all to changes does not cause the deletion of the zone-in-journal and the behaviour of the zone loading procedure might be different than expected. It is recommended to consider purging the journal when this option is changed.
journal-max-usage¶
Policy how much space in journal DB will the zone's journal occupy.
Note
Journal DB may grow far above the sum of journal-max-usage across all zones, because of DB free space fragmentation.
Default: 100M (100 MiB)
journal-max-depth¶
Maximum history length of the journal.
Note
Zone-in-journal changeset isn't counted to the limit.
Minimum: 2
Default: 20
ixfr-by-one¶
Within incoming IXFR, process only one changeset at a time, not multiple together. This preserves the complete history in the journal and prevents the merging of changesets when multiple changesets are IXFRed simultaneously. However, this does not prevent the merging (or deletion) of old changesets in the journal to save space, as described in journal behaviour.
This option leads to increased server load when processing IXFR, including network traffic.
Default: off
zone-max-size¶
Maximum size of the zone. The size is measured as size of the zone records in wire format without compression. The limit is enforced for incoming zone transfers and dynamic updates.
For incremental transfers (IXFR), the effective limit for the total size of the records in the transfer is twice the configured value. However the final size of the zone must satisfy the configured value.
Default: unlimited
adjust-threads¶
Parallelize internal zone adjusting procedures by using specified number of threads. This is useful with huge zones with NSEC3. Speedup observable at server startup and while processing NSEC3 re-salt.
Default: 1 (no extra threads)
dnssec-signing¶
If enabled, automatic DNSSEC signing for the zone is turned on.
Default: off
dnssec-validation¶
If enabled, the zone contents are validated for being correctly signed (including NSEC/NSEC3 chain) with DNSSEC signatures every time the zone is loaded or changed (including AXFR/IXFR).
When the validation fails, the zone being loaded or update being applied is cancelled with an error, and either none or previous zone state is published.
List of DNSSEC checks:
Every zone RRSet is correctly signed by at least one present DNSKEY.
DNSKEY RRSet is signed by KSK.
NSEC(3) RR exists for each name (unless opt-out) with correct bitmap.
Every NSEC(3) RR is linked to the lexicographically next one.
The validation is not affected by dnssec-policy configuration, except for signing-threads option, which specifies the number of threads for parallel validation.
Note
Redundant or garbage NSEC3 records are ignored.
This mode is not compatible with dnssec-signing.
Default: not set
dnssec-policy¶
A reference to DNSSEC signing policy.
Note
A configured policy called "default" won't be used unless explicitly referenced.
Default: an imaginary policy with all default values
ds-push¶
Per zone configuration of ds-push. This option overrides possible per policy option.
Default: not set
zonemd-verify¶
On each zone load/update, verify that ZONEMD is present in the zone and valid.
Note
Zone digest calculation may take much time and CPU on large zones.
Default: off
zonemd-generate¶
On each zone update, calculate ZONEMD and put it into the zone.
Possible values:
none– No action regarding ZONEMD.zonemd-sha384– Generate ZONEMD using SHA384 algorithm.zonemd-sha512– Generate ZONEMD using SHA512 algorithm.remove– Remove any ZONEMD from the zone apex.
Default: none
serial-policy¶
Specifies how the zone serial is updated after a dynamic update or automatic DNSSEC signing. If the serial is changed by the dynamic update, no change is made.
Possible values:
increment– The serial is incremented according to serial number arithmetic.unixtime– The serial is set to the current unix time.dateserial– The 10-digit serial (YYYYMMDDnn) is incremented, the first 8 digits match the current iso-date.
Note
If the resulting serial for unixtime or dateserial is lower than or equal to the current serial (this happens e.g. when migrating from other policy or frequent updates), the serial is incremented instead.
To avoid user confusion, use dateserial only if you expect at most 100 updates per day per zone and unixtime only if you expect at most one update per second per zone.
Generated catalog zones use unixtime only.
Default: increment (unixtime for generated catalog zones)
refresh-min-interval¶
Forced minimum zone refresh interval (in seconds) to avoid flooding primary server.
Minimum: 2
Default: 2
refresh-max-interval¶
Forced maximum zone refresh interval (in seconds).
Default: not set
retry-min-interval¶
Forced minimum zone retry interval (in seconds) to avoid flooding primary server.
Minimum: 1
Default: 1
retry-max-interval¶
Forced maximum zone retry interval (in seconds).
Default: not set
expire-min-interval¶
Forced minimum zone expire interval (in seconds) to avoid flooding primary server.
Minimum: 3
Default: 3
expire-max-interval¶
Forced maximum zone expire interval (in seconds).
Default: not set
catalog-role¶
Trigger zone catalog feature. Possible values:
none– Not a catalog zone.interpret– A catalog zone which is loaded from a zone file or XFR, and member zones shall be configured based on its contents.generate– A catalog zone whose contents are generated according to assigned member zones.member– A member zone that is assigned to one generated catalog zone.
Note
If set to generate, the zonefile-load option has no effect since a zone file is never loaded.
Default: none
catalog-template¶
For the catalog member zones, the specified configuration template will be applied.
Multiple catalog templates may be defined. The first one is used unless the member zone has the group property defined, matching another catalog template.
Note
This option must be set if and only if catalog-role is interpret.
Nested catalog zones aren't supported. Therefore catalog templates can't use catalog-template, catalog-role, catalog-zone, and catalog-group options.
Default: not set
catalog-zone¶
Assign this member zone to specified generated catalog zone.
Note
This option must be set if and only if catalog-role is member.
The referenced catalog zone must exist and have catalog-role set to generate.
Default: not set
catalog-group¶
Assign this member zone to specified catalog group (configuration template).
Note
This option has effect if and only if catalog-role is member.
Default: not set
module¶
An ordered list of references to query modules in the form of module_name or module_name/module_id. These modules apply only to the current zone queries.
Default: not set
Comments¶
A comment begins with a
#character and is ignored during processing. Also each configuration section or sequence block allows a permanent comment using thecommentitem which is stored in the server beside the configuration.