packages icon



 unbound.conf(5)                 NLnet Labs                  unbound.conf(5)
 unbound 1.10.1                                               unbound 1.10.1

                                May 19, 2020



 NAME
      unbound.conf - Unbound configuration file.

 SYNOPSIS
      unbound.conf

 DESCRIPTION
      unbound.conf is used to configure unbound(8).  The file format has
      attributes and values. Some attributes have attributes inside them.
      The notation is: attribute: value.

      Comments start with # and last to the end of line. Empty lines are
      ignored as is whitespace at the beginning of a line.

      The utility unbound-checkconf(8) can be used to check unbound.conf
      prior to usage.

 EXAMPLE
      An example config file is shown below. Copy this to
      /etc/unbound/unbound.conf and start the server with:

           $ unbound -c /etc/unbound/unbound.conf

      Most settings are the defaults. Stop the server with:

           $ kill `cat /etc/unbound/unbound.pid`

      Below is a minimal config file. The source distribution contains an
      extensive example.conf file with all the options.

      # unbound.conf(5) config file for unbound(8).
      server:
           directory: "/etc/unbound"
           username: unbound
           # make sure unbound can access entropy from inside the chroot.
           # e.g. on linux the use these commands (on BSD, devfs(8) is used):
           #      mount --bind -n /dev/urandom /etc/unbound/dev/urandom
           # and  mount --bind -n /dev/log /etc/unbound/dev/log
           chroot: "/etc/unbound"
           # logfile: "/etc/unbound/unbound.log"  #uncomment to use logfile.
           pidfile: "/etc/unbound/unbound.pid"
           # verbosity: 1      # uncomment and increase to get more logging.
           # listen on all interfaces, answer queries from the local subnet.
           interface: 0.0.0.0
           interface: ::0
           access-control: 10.0.0.0/8 allow
           access-control: 2001:DB8::/64 allow

 FILE FORMAT



                                    - 1 -           Formatted:  June 4, 2020






 unbound.conf(5)                 NLnet Labs                  unbound.conf(5)
 unbound 1.10.1                                               unbound 1.10.1

                                May 19, 2020



      There must be whitespace between keywords.  Attribute keywords end
      with a colon ':'.  An attribute is followed by a value, or its
      containing attributes in which case it is referred to as a clause.
      Clauses can be repeated throughout the file (or included files) to
      group attributes under the same clause.

      Files can be included using the include: directive. It can appear
      anywhere, it accepts a single file name as argument.  Processing
      continues as if the text from the included file was copied into the
      config file at that point.  If also using chroot, using full path
      names for the included files works, relative pathnames for the
      included names work if the directory where the daemon is started
      equals its chroot/working directory or is specified before the include
      statement with directory: dir.  Wildcards can be used to include
      multiple files, see glob(7).

    Server Options
      These options are part of the server: clause.

      verbosity: <number>
           The verbosity number, level 0 means no verbosity, only errors.
           Level 1 gives operational information. Level 2 gives detailed
           operational information. Level 3 gives query level information,
           output per query.  Level 4 gives algorithm level information.
           Level 5 logs client identification for cache misses.  Default is
           level 1.  The verbosity can also be increased from the
           commandline, see unbound(8).

      statistics-interval: <seconds>
           The number of seconds between printing statistics to the log for
           every thread.  Disable with value 0 or "". Default is disabled.
           The histogram statistics are only printed if replies were sent
           during the statistics interval, requestlist statistics are
           printed for every interval (but can be 0).  This is because the
           median calculation requires data to be present.

      statistics-cumulative: <yes or no>
           If enabled, statistics are cumulative since starting unbound,
           without clearing the statistics counters after logging the
           statistics. Default is no.

      extended-statistics: <yes or no>
           If enabled, extended statistics are printed from
           unbound-control(8).  Default is off, because keeping track of
           more statistics takes time.  The counters are listed in
           unbound-control(8).

      num-threads: <number>
           The number of threads to create to serve clients. Use 1 for no



                                    - 2 -           Formatted:  June 4, 2020






 unbound.conf(5)                 NLnet Labs                  unbound.conf(5)
 unbound 1.10.1                                               unbound 1.10.1

                                May 19, 2020



           threading.

      port: <port number>
           The port number, default 53, on which the server responds to
           queries.

      interface: <ip address[@port]>
           Interface to use to connect to the network. This interface is
           listened to for queries from clients, and answers to clients are
           given from it.  Can be given multiple times to work on several
           interfaces. If none are given the default is to listen to
           localhost.  The interfaces are not changed on a reload (kill
           -HUP) but only on restart.  A port number can be specified with
           @port (without spaces between interface and port number), if not
           specified the default port (from port) is used.

      ip-address: <ip address[@port]>
           Same as interface: (for ease of compatibility with nsd.conf).

      interface-automatic: <yes or no>
           Detect source interface on UDP queries and copy them to replies.
           This feature is experimental, and needs support in your OS for
           particular socket options.  Default value is no.

      outgoing-interface: <ip address or ip6 netblock>
           Interface to use to connect to the network. This interface is
           used to send queries to authoritative servers and receive their
           replies. Can be given multiple times to work on several
           interfaces. If none are given the default (all) is used. You can
           specify the same interfaces in interface: and outgoing-interface:
           lines, the interfaces are then used for both purposes. Outgoing
           queries are sent via a random outgoing interface to counter
           spoofing.

           If an IPv6 netblock is specified instead of an individual IPv6
           address, outgoing UDP queries will use a randomised source
           address taken from the netblock to counter spoofing. Requires the
           IPv6 netblock to be routed to the host running unbound, and
           requires OS support for unprivileged non-local binds (currently
           only supported on Linux). Several netblocks may be specified with
           multiple outgoing-interface: options, but do not specify both an
           individual IPv6 address and an IPv6 netblock, or the
           randomisation will be compromised.  Consider combining with
           prefer-ip6: yes to increase the likelihood of IPv6 nameservers
           being selected for queries.  On Linux you need these two commands
           to be able to use the freebind socket option to receive traffic
           for the ip6 netblock: ip -6 addr add mynetblock/64 dev lo && ip
           -6 route add local mynetblock/64 dev lo




                                    - 3 -           Formatted:  June 4, 2020






 unbound.conf(5)                 NLnet Labs                  unbound.conf(5)
 unbound 1.10.1                                               unbound 1.10.1

                                May 19, 2020



      outgoing-range: <number>
           Number of ports to open. This number of file descriptors can be
           opened per thread. Must be at least 1. Default depends on compile
           options. Larger numbers need extra resources from the operating
           system.  For performance a very large value is best, use libevent
           to make this possible.

      outgoing-port-permit: <port number or range>
           Permit unbound to open this port or range of ports for use to
           send queries.  A larger number of permitted outgoing ports
           increases resilience against spoofing attempts. Make sure these
           ports are not needed by other daemons.  By default only ports
           above 1024 that have not been assigned by IANA are used.  Give a
           port number or a range of the form "low-high", without spaces.

           The outgoing-port-permit and outgoing-port-avoid statements are
           processed in the line order of the config file, adding the
           permitted ports and subtracting the avoided ports from the set of
           allowed ports.  The processing starts with the non IANA allocated
           ports above 1024 in the set of allowed ports.

      outgoing-port-avoid: <port number or range>
           Do not permit unbound to open this port or range of ports for use
           to send queries. Use this to make sure unbound does not grab a
           port that another daemon needs. The port is avoided on all
           outgoing interfaces, both IP4 and IP6.  By default only ports
           above 1024 that have not been assigned by IANA are used.  Give a
           port number or a range of the form "low-high", without spaces.

      outgoing-num-tcp: <number>
           Number of outgoing TCP buffers to allocate per thread. Default is
           10. If set to 0, or if do-tcp is "no", no TCP queries to
           authoritative servers are done.  For larger installations
           increasing this value is a good idea.

      incoming-num-tcp: <number>
           Number of incoming TCP buffers to allocate per thread. Default is
           10. If set to 0, or if do-tcp is "no", no TCP queries from
           clients are accepted. For larger installations increasing this
           value is a good idea.

      edns-buffer-size: <number>
           Number of bytes size to advertise as the EDNS reassembly buffer
           size.  This is the value put into datagrams over UDP towards
           peers.  The actual buffer size is determined by msg-buffer-size
           (both for TCP and UDP).  Do not set higher than that value.
           Default is 4096 which is RFC recommended.  If you have
           fragmentation reassembly problems, usually seen as timeouts, then
           a value of 1472 can fix it.  Setting to 512 bypasses even the



                                    - 4 -           Formatted:  June 4, 2020






 unbound.conf(5)                 NLnet Labs                  unbound.conf(5)
 unbound 1.10.1                                               unbound 1.10.1

                                May 19, 2020



           most stringent path MTU problems, but is seen as extreme, since
           the amount of TCP fallback generated is excessive (probably also
           for this resolver, consider tuning the outgoing tcp number).

      max-udp-size: <number>
           Maximum UDP response size (not applied to TCP response).  65536
           disables the udp response size maximum, and uses the choice from
           the client, always.  Suggested values are 512 to 4096. Default is
           4096.

      stream-wait-size: <number>
           Number of bytes size maximum to use for waiting stream buffers.
           Default is 4 megabytes.  A plain number is in bytes, append 'k',
           'm' or 'g' for kilobytes, megabytes or gigabytes (1024*1024 bytes
           in a megabyte).  As TCP and TLS streams queue up multiple
           results, the amount of memory used for these buffers does not
           exceed this number, otherwise the responses are dropped.  This
           manages the total memory usage of the server (under heavy use),
           the number of requests that can be queued up per connection is
           also limited, with further requests waiting in TCP buffers.

      msg-buffer-size: <number>
           Number of bytes size of the message buffers. Default is 65552
           bytes, enough for 64 Kb packets, the maximum DNS message size. No
           message larger than this can be sent or received. Can be reduced
           to use less memory, but some requests for DNS data, such as for
           huge resource records, will result in a SERVFAIL reply to the
           client.

      msg-cache-size: <number>
           Number of bytes size of the message cache. Default is 4
           megabytes.  A plain number is in bytes, append 'k', 'm' or 'g'
           for kilobytes, megabytes or gigabytes (1024*1024 bytes in a
           megabyte).

      msg-cache-slabs: <number>
           Number of slabs in the message cache. Slabs reduce lock
           contention by threads.  Must be set to a power of 2. Setting
           (close) to the number of cpus is a reasonable guess.

      num-queries-per-thread: <number>
           The number of queries that every thread will service
           simultaneously.  If more queries arrive that need servicing, and
           no queries can be jostled out (see jostle-timeout), then the
           queries are dropped. This forces the client to resend after a
           timeout; allowing the server time to work on the existing
           queries. Default depends on compile options, 512 or 1024.

      jostle-timeout: <msec>



                                    - 5 -           Formatted:  June 4, 2020






 unbound.conf(5)                 NLnet Labs                  unbound.conf(5)
 unbound 1.10.1                                               unbound 1.10.1

                                May 19, 2020



           Timeout used when the server is very busy.  Set to a value that
           usually results in one roundtrip to the authority servers.  If
           too many queries arrive, then 50% of the queries are allowed to
           run to completion, and the other 50% are replaced with the new
           incoming query if they have already spent more than their allowed
           time.  This protects against denial of service by slow queries or
           high query rates.  Default 200 milliseconds.  The effect is that
           the qps for long-lasting queries is about (numqueriesperthread /
           2) / (average time for such long queries) qps.  The qps for short
           queries can be about (numqueriesperthread / 2) / (jostletimeout
           in whole seconds) qps per thread, about (1024/2)*5 = 2560 qps by
           default.

      delay-close: <msec>
           Extra delay for timeouted UDP ports before they are closed, in
           msec.  Default is 0, and that disables it.  This prevents very
           delayed answer packets from the upstream (recursive) servers from
           bouncing against closed ports and setting off all sort of close-
           port counters, with eg. 1500 msec.  When timeouts happen you need
           extra sockets, it checks the ID and remote IP of packets, and
           unwanted packets are added to the unwanted packet counter.

      unknown-server-time-limit: <msec>
           The wait time in msec for waiting for an unknown server to reply.
           Increase this if you are behind a slow satellite link, to eg.
           1128.  That would then avoid re-querying every initial query
           because it times out.  Default is 376 msec.

      so-rcvbuf: <number>
           If not 0, then set the SO_RCVBUF socket option to get more buffer
           space on UDP port 53 incoming queries.  So that short spikes on
           busy servers do not drop packets (see counter in netstat -su).
           Default is 0 (use system value).  Otherwise, the number of bytes
           to ask for, try "4m" on a busy server.  The OS caps it at a
           maximum, on linux unbound needs root permission to bypass the
           limit, or the admin can use sysctl net.core.rmem_max.  On BSD
           change kern.ipc.maxsockbuf in /etc/sysctl.conf.  On OpenBSD
           change header and recompile kernel. On Solaris ndd -set /dev/udp
           udp_max_buf 8388608.

      so-sndbuf: <number>
           If not 0, then set the SO_SNDBUF socket option to get more buffer
           space on UDP port 53 outgoing queries.  This for very busy
           servers handles spikes in answer traffic, otherwise 'send:
           resource temporarily unavailable' can get logged, the buffer
           overrun is also visible by netstat -su.  Default is 0 (use system
           value).  Specify the number of bytes to ask for, try "4m" on a
           very busy server.  The OS caps it at a maximum, on linux unbound
           needs root permission to bypass the limit, or the admin can use



                                    - 6 -           Formatted:  June 4, 2020






 unbound.conf(5)                 NLnet Labs                  unbound.conf(5)
 unbound 1.10.1                                               unbound 1.10.1

                                May 19, 2020



           sysctl net.core.wmem_max.  On BSD, Solaris changes are similar to
           so-rcvbuf.

      so-reuseport: <yes or no>
           If yes, then open dedicated listening sockets for incoming
           queries for each thread and try to set the SO_REUSEPORT socket
           option on each socket.  May distribute incoming queries to
           threads more evenly.  Default is yes.  On Linux it is supported
           in kernels >= 3.9.  On other systems, FreeBSD, OSX it may also
           work.  You can enable it (on any platform and kernel), it then
           attempts to open the port and passes the option if it was
           available at compile time, if that works it is used, if it fails,
           it continues silently (unless verbosity 3) without the option.
           At extreme load it could be better to turn it off to distribute
           the queries evenly, reported for Linux systems (4.4.x).

      ip-transparent: <yes or no>
           If yes, then use IP_TRANSPARENT socket option on sockets where
           unbound is listening for incoming traffic.  Default no.  Allows
           you to bind to non-local interfaces.  For example for
           non-existent IP addresses that are going to exist later on, with
           host failover configuration.  This is a lot like
           interface-automatic, but that one services all interfaces and
           with this option you can select which (future) interfaces unbound
           provides service on.  This option needs unbound to be started
           with root permissions on some systems.  The option uses
           IP_BINDANY on FreeBSD systems and SO_BINDANY on OpenBSD systems.

      ip-freebind: <yes or no>
           If yes, then use IP_FREEBIND socket option on sockets where
           unbound is listening to incoming traffic.  Default no.  Allows
           you to bind to IP addresses that are nonlocal or do not exist,
           like when the network interface or IP address is down.  Exists
           only on Linux, where the similar ip-transparent option is also
           available.

      rrset-cache-size: <number>
           Number of bytes size of the RRset cache. Default is 4 megabytes.
           A plain number is in bytes, append 'k', 'm' or 'g' for kilobytes,
           megabytes or gigabytes (1024*1024 bytes in a megabyte).

      rrset-cache-slabs: <number>
           Number of slabs in the RRset cache. Slabs reduce lock contention
           by threads.  Must be set to a power of 2.

      cache-max-ttl: <seconds>
           Time to live maximum for RRsets and messages in the cache.
           Default is 86400 seconds (1 day).  When the TTL expires, the
           cache item has expired.  Can be set lower to force the resolver



                                    - 7 -           Formatted:  June 4, 2020






 unbound.conf(5)                 NLnet Labs                  unbound.conf(5)
 unbound 1.10.1                                               unbound 1.10.1

                                May 19, 2020



           to query for data often, and not trust (very large) TTL values.
           Downstream clients also see the lower TTL.

      cache-min-ttl: <seconds>
           Time to live minimum for RRsets and messages in the cache.
           Default is 0.  If the minimum kicks in, the data is cached for
           longer than the domain owner intended, and thus less queries are
           made to look up the data.  Zero makes sure the data in the cache
           is as the domain owner intended, higher values, especially more
           than an hour or so, can lead to trouble as the data in the cache
           does not match up with the actual data any more.

      cache-max-negative-ttl: <seconds>
           Time to live maximum for negative responses, these have a SOA in
           the authority section that is limited in time.  Default is 3600.
           This applies to nxdomain and nodata answers.

      infra-host-ttl: <seconds>
           Time to live for entries in the host cache. The host cache
           contains roundtrip timing, lameness and EDNS support information.
           Default is 900.

      infra-cache-slabs: <number>
           Number of slabs in the infrastructure cache. Slabs reduce lock
           contention by threads. Must be set to a power of 2.

      infra-cache-numhosts: <number>
           Number of hosts for which information is cached. Default is
           10000.

      infra-cache-min-rtt: <msec>
           Lower limit for dynamic retransmit timeout calculation in
           infrastructure cache. Default is 50 milliseconds. Increase this
           value if using forwarders needing more time to do recursive name
           resolution.

      define-tag: <"list of tags">
           Define the tags that can be used with local-zone and
           access-control.  Enclose the list between quotes ("") and put
           spaces between tags.

      do-ip4: <yes or no>
           Enable or disable whether ip4 queries are answered or issued.
           Default is yes.

      do-ip6: <yes or no>
           Enable or disable whether ip6 queries are answered or issued.
           Default is yes.  If disabled, queries are not answered on IPv6,
           and queries are not sent on IPv6 to the internet nameservers.



                                    - 8 -           Formatted:  June 4, 2020






 unbound.conf(5)                 NLnet Labs                  unbound.conf(5)
 unbound 1.10.1                                               unbound 1.10.1

                                May 19, 2020



           With this option you can disable the ipv6 transport for sending
           DNS traffic, it does not impact the contents of the DNS traffic,
           which may have ip4 and ip6 addresses in it.

      prefer-ip6: <yes or no>
           If enabled, prefer IPv6 transport for sending DNS queries to
           internet nameservers. Default is no.

      do-udp: <yes or no>
           Enable or disable whether UDP queries are answered or issued.
           Default is yes.

      do-tcp: <yes or no>
           Enable or disable whether TCP queries are answered or issued.
           Default is yes.

      tcp-mss: <number>
           Maximum segment size (MSS) of TCP socket on which the server
           responds to queries. Value lower than common MSS on Ethernet
           (1220 for example) will address path MTU problem.  Note that not
           all platform supports socket option to set MSS (TCP_MAXSEG).
           Default is system default MSS determined by interface MTU and
           negotiation between server and client.

      outgoing-tcp-mss: <number>
           Maximum segment size (MSS) of TCP socket for outgoing queries
           (from Unbound to other servers). Value lower than common MSS on
           Ethernet (1220 for example) will address path MTU problem.  Note
           that not all platform supports socket option to set MSS
           (TCP_MAXSEG).  Default is system default MSS determined by
           interface MTU and negotiation between Unbound and other servers.

      tcp-idle-timeout: <msec>
           The period Unbound will wait for a query on a TCP connection.  If
           this timeout expires Unbound closes the connection.  This option
           defaults to 30000 milliseconds.  When the number of free incoming
           TCP buffers falls below 50% of the total number configured, the
           option value used is progressively reduced, first to 1% of the
           configured value, then to 0.2% of the configured value if the
           number of free buffers falls below 35% of the total number
           configured, and finally to 0 if the number of free buffers falls
           below 20% of the total number configured. A minimum timeout of
           200 milliseconds is observed regardless of the option value used.

      edns-tcp-keepalive: <yes or no>
           Enable or disable EDNS TCP Keepalive. Default is no.

      edns-tcp-keepalive-timeout: <msec>
           The period Unbound will wait for a query on a TCP connection when



                                    - 9 -           Formatted:  June 4, 2020






 unbound.conf(5)                 NLnet Labs                  unbound.conf(5)
 unbound 1.10.1                                               unbound 1.10.1

                                May 19, 2020



           EDNS TCP Keepalive is active. If this timeout expires Unbound
           closes the connection. If the client supports the EDNS TCP
           Keepalive option, Unbound sends the timeout value to the client
           to encourage it to close the connection before the server times
           out.  This option defaults to 120000 milliseconds.  When the
           number of free incoming TCP buffers falls below 50% of the total
           number configured, the advertised timeout is progressively
           reduced to 1% of the configured value, then to 0.2% of the
           configured value if the number of free buffers falls below 35% of
           the total number configured, and finally to 0 if the number of
           free buffers falls below 20% of the total number configured.  A
           minimum actual timeout of 200 milliseconds is observed regardless
           of the advertised timeout.

      tcp-upstream: <yes or no>
           Enable or disable whether the upstream queries use TCP only for
           transport.  Default is no.  Useful in tunneling scenarios.

      udp-upstream-without-downstream: <yes or no>
           Enable udp upstream even if do-udp is no.  Default is no, and
           this does not change anything.  Useful for TLS service providers,
           that want no udp downstream but use udp to fetch data upstream.

      tls-upstream: <yes or no>
           Enabled or disable whether the upstream queries use TLS only for
           transport.  Default is no.  Useful in tunneling scenarios.  The
           TLS contains plain DNS in TCP wireformat.  The other server must
           support this (see tls-service-key).  If you enable this, also
           configure a tls-cert-bundle or use tls-win-cert to load CA certs,
           otherwise the connections cannot be authenticated.  This option
           enables TLS for all of them, but if you do not set this you can
           configure TLS specifically for some forward zones with
           forward-tls-upstream.  And also with stub-tls-upstream.

      ssl-upstream: <yes or no>
           Alternate syntax for tls-upstream.  If both are present in the
           config file the last is used.

      tls-service-key: <file>
           If enabled, the server provides TLS service on the TCP ports
           marked implicitly or explicitly for TLS service with tls-port.
           The file must contain the private key for the TLS session, the
           public certificate is in the tls-service-pem file and it must
           also be specified if tls-service-key is specified.  The default
           is "", turned off.  Enabling or disabling this service requires a
           restart (a reload is not enough), because the key is read while
           root permissions are held and before chroot (if any).  The ports
           enabled implicitly or explicitly via tls-port: do not provide
           normal DNS TCP service.



                                   - 10 -           Formatted:  June 4, 2020






 unbound.conf(5)                 NLnet Labs                  unbound.conf(5)
 unbound 1.10.1                                               unbound 1.10.1

                                May 19, 2020



      ssl-service-key: <file>
           Alternate syntax for tls-service-key.

      tls-service-pem: <file>
           The public key certificate pem file for the tls service.  Default
           is "", turned off.

      ssl-service-pem: <file>
           Alternate syntax for tls-service-pem.

      tls-port: <number>
           The port number on which to provide TCP TLS service, default 853,
           only interfaces configured with that port number as @number get
           the TLS service.

      ssl-port: <number>
           Alternate syntax for tls-port.

      tls-cert-bundle: <file>
           If null or "", no file is used.  Set it to the certificate bundle
           file, for example "/etc/pki/tls/certs/ca-bundle.crt".  These
           certificates are used for authenticating connections made to
           outside peers.  For example auth-zone urls, and also DNS over TLS
           connections.

      ssl-cert-bundle: <file>
           Alternate syntax for tls-cert-bundle.

      tls-win-cert: <yes or no>
           Add the system certificates to the cert bundle certificates for
           authentication.  If no cert bundle, it uses only these
           certificates.  Default is no.  On windows this option uses the
           certificates from the cert store.  Use the tls-cert-bundle option
           on other systems.

      tls-additional-port: <portnr>
           List portnumbers as tls-additional-port, and when interfaces are
           defined, eg. with the @port suffix, as this port number, they
           provide dns over TLS service.  Can list multiple, each on a new
           statement.

      tls-session-ticket-keys: <file>
           If not "", lists files with 80 bytes of random contents that are
           used to perform TLS session resumption for clients using the
           unbound server.  These files contain the secret key for the TLS
           session tickets.  First key use to encrypt and decrypt TLS
           session tickets.  Other keys use to decrypt only.  With this you
           can roll over to new keys, by generating a new first file and
           allowing decrypt of the old file by listing it after the first



                                   - 11 -           Formatted:  June 4, 2020






 unbound.conf(5)                 NLnet Labs                  unbound.conf(5)
 unbound 1.10.1                                               unbound 1.10.1

                                May 19, 2020



           file for some time, after the wait clients are not using the old
           key any more and the old key can be removed.  One way to create
           the file is dd if=/dev/random bs=1 count=80 of=ticket.dat The
           first 16 bytes should be different from the old one if you create
           a second key, that is the name used to identify the key.  Then
           there is 32 bytes random data for an AES key and then 32 bytes
           random data for the HMAC key.

      tls-ciphers: <string with cipher list>
           Set the list of ciphers to allow when serving TLS.  Use "" for
           defaults, and that is the default.

      tls-ciphersuites: <string with ciphersuites list>
           Set the list of ciphersuites to allow when serving TLS.  This is
           for newer TLS 1.3 connections.  Use "" for defaults, and that is
           the default.

      use-systemd: <yes or no>
           Enable or disable systemd socket activation.  Default is no.

      do-daemonize: <yes or no>
           Enable or disable whether the unbound server forks into the
           background as a daemon.  Set the value to no when unbound runs as
           systemd service.  Default is yes.

      tcp-connection-limit: <IP netblock> <limit>
           Allow up to limit simultaneous TCP connections from the given
           netblock.  When at the limit, further connections are accepted
           but closed immediately.  This option is experimental at this
           time.

      access-control: <IP netblock> <action>
           The netblock is given as an IP4 or IP6 address with /size
           appended for a classless network block. The action can be deny,
           refuse, allow, allow_setrd, allow_snoop, deny_non_local or
           refuse_non_local.  The most specific netblock match is used, if
           none match deny is used.  The order of the access-control
           statements therefore does not matter.

           The action deny stops queries from hosts from that netblock.

           The action refuse stops queries too, but sends a DNS rcode
           REFUSED error message back.

           The action allow gives access to clients from that netblock.  It
           gives only access for recursion clients (which is what almost all
           clients need).  Nonrecursive queries are refused.

           The allow action does allow nonrecursive queries to access the



                                   - 12 -           Formatted:  June 4, 2020






 unbound.conf(5)                 NLnet Labs                  unbound.conf(5)
 unbound 1.10.1                                               unbound 1.10.1

                                May 19, 2020



           local-data that is configured.  The reason is that this does not
           involve the unbound server recursive lookup algorithm, and static
           data is served in the reply.  This supports normal operations
           where nonrecursive queries are made for the authoritative data.
           For nonrecursive queries any replies from the dynamic cache are
           refused.

           The allow_setrd action ignores the recursion desired (RD) bit and
           treats all requests as if the recursion desired bit is set.  Note
           that this behavior violates RFC 1034 which states that a name
           server should never perform recursive service unless asked via
           the RD bit since this interferes with trouble shooting of name
           servers and their databases. This prohibited behavior may be
           useful if another DNS server must forward requests for specific
           zones to a resolver DNS server, but only supports stub domains
           and sends queries to the resolver DNS server with the RD bit
           cleared.

           The action allow_snoop gives nonrecursive access too.  This give
           both recursive and non recursive access.  The name allow_snoop
           refers to cache snooping, a technique to use nonrecursive queries
           to examine the cache contents (for malicious acts).  However,
           nonrecursive queries can also be a valuable debugging tool (when
           you want to examine the cache contents). In that case use
           allow_snoop for your administration host.

           By default only localhost is allowed, the rest is refused.  The
           default is refused, because that is protocol-friendly. The DNS
           protocol is not designed to handle dropped packets due to policy,
           and dropping may result in (possibly excessive) retried queries.

           The deny_non_local and refuse_non_local settings are for hosts
           that are only allowed to query for the authoritative local-data,
           they are not allowed full recursion but only the static data.
           With deny_non_local, messages that are disallowed are dropped,
           with refuse_non_local they receive error code REFUSED.

      access-control-tag: <IP netblock> <"list of tags">
           Assign tags to access-control elements. Clients using this access
           control element use localzones that are tagged with one of these
           tags. Tags must be defined in define-tags.  Enclose list of tags
           in quotes ("") and put spaces between tags. If access-control-tag
           is configured for a netblock that does not have an
           access-control, an access-control element with action allow is
           configured for this netblock.

      access-control-tag-action: <IP netblock> <tag> <action>
           Set action for particular tag for given access control element.
           If you have multiple tag values, the tag used to lookup the



                                   - 13 -           Formatted:  June 4, 2020






 unbound.conf(5)                 NLnet Labs                  unbound.conf(5)
 unbound 1.10.1                                               unbound 1.10.1

                                May 19, 2020



           action is the first tag match between access-control-tag and
           local-zone-tag where "first" comes from the order of the define-
           tag values.

      access-control-tag-data: <IP netblock> <tag> <"resource record
           Set redirect data for particular tag for given access control
           element.

      access-control-view: <IP netblock> <view name>
           Set view for given access control element.

      chroot: <directory>
           If chroot is enabled, you should pass the configfile (from the
           commandline) as a full path from the original root. After the
           chroot has been performed the now defunct portion of the config
           file path is removed to be able to reread the config after a
           reload.

           All other file paths (working dir, logfile, roothints, and key
           files) can be specified in several ways: as an absolute path
           relative to the new root, as a relative path to the working
           directory, or as an absolute path relative to the original root.
           In the last case the path is adjusted to remove the unused
           portion.

           The pidfile can be either a relative path to the working
           directory, or an absolute path relative to the original root. It
           is written just prior to chroot and dropping permissions. This
           allows the pidfile to be /var/run/unbound.pid and the chroot to
           be /var/unbound, for example. Note that Unbound is not able to
           remove the pidfile after termination when it is located outside
           of the chroot directory.

           Additionally, unbound may need to access /dev/urandom (for
           entropy) from inside the chroot.

           If given a chroot is done to the given directory. By default
           chroot is enabled and the default is "/usr/local/etc/unbound". If
           you give "" no chroot is performed.

      username: <name>
           If given, after binding the port the user privileges are dropped.
           Default is "unbound". If you give username: "" no user change is
           performed.

           If this user is not capable of binding the port, reloads (by
           signal HUP) will still retain the opened ports.  If you change
           the port number in the config file, and that new port number
           requires privileges, then a reload will fail; a restart is



                                   - 14 -           Formatted:  June 4, 2020






 unbound.conf(5)                 NLnet Labs                  unbound.conf(5)
 unbound 1.10.1                                               unbound 1.10.1

                                May 19, 2020



           needed.

      directory: <directory>
           Sets the working directory for the program. Default is
           "/usr/local/etc/unbound".  On Windows the string "%EXECUTABLE%"
           tries to change to the directory that unbound.exe resides in.  If
           you give a server: directory: dir before include: file statements
           then those includes can be relative to the working directory.

      logfile: <filename>
           If "" is given, logging goes to stderr, or nowhere once
           daemonized.  The logfile is appended to, in the following format:
           [seconds since 1970] unbound[pid:tid]: type: message.
           If this option is given, the use-syslog is option is set to "no".
           The logfile is reopened (for append) when the config file is
           reread, on SIGHUP.

      use-syslog: <yes or no>
           Sets unbound to send log messages to the syslogd, using
           syslog(3).  The log facility LOG_DAEMON is used, with identity
           "unbound".  The logfile setting is overridden when use-syslog is
           turned on.  The default is to log to syslog.

      log-identity: <string>
           If "" is given (default), then the name of the executable,
           usually "unbound" is used to report to the log.  Enter a string
           to override it with that, which is useful on systems that run
           more than one instance of unbound, with different configurations,
           so that the logs can be easily distinguished against.

      log-time-ascii: <yes or no>
           Sets logfile lines to use a timestamp in UTC ascii. Default is
           no, which prints the seconds since 1970 in brackets. No effect if
           using syslog, in that case syslog formats the timestamp printed
           into the log files.

      log-queries: <yes or no>
           Prints one line per query to the log, with the log timestamp and
           IP address, name, type and class.  Default is no.  Note that it
           takes time to print these lines which makes the server
           (significantly) slower.  Odd (nonprintable) characters in names
           are printed as '?'.

      log-replies: <yes or no>
           Prints one line per reply to the log, with the log timestamp and
           IP address, name, type, class, return code, time to resolve, from
           cache and response size.  Default is no.  Note that it takes time
           to print these lines which makes the server (significantly)
           slower.  Odd (nonprintable) characters in names are printed as



                                   - 15 -           Formatted:  June 4, 2020






 unbound.conf(5)                 NLnet Labs                  unbound.conf(5)
 unbound 1.10.1                                               unbound 1.10.1

                                May 19, 2020



           '?'.

      log-tag-queryreply: <yes or no>
           Prints the word 'query' and 'reply' with log-queries and
           log-replies.  This makes filtering logs easier.  The default is
           off (for backwards compatibility).

      log-local-actions: <yes or no>
           Print log lines to inform about local zone actions.  These lines
           are like the local-zone type inform prints out, but they are also
           printed for the other types of local zones.

      log-servfail: <yes or no>
           Print log lines that say why queries return SERVFAIL to clients.
           This is separate from the verbosity debug logs, much smaller, and
           printed at the error level, not the info level of debug info from
           verbosity.

      pidfile: <filename>
           The process id is written to the file. Default is
           "/usr/local/etc/unbound/unbound.pid".  So,
           kill -HUP `cat /usr/local/etc/unbound/unbound.pid`
           triggers a reload,
           kill -TERM `cat /usr/local/etc/unbound/unbound.pid`
           gracefully terminates.

      root-hints: <filename>
           Read the root hints from this file. Default is nothing, using
           builtin hints for the IN class. The file has the format of zone
           files, with root nameserver names and addresses only. The default
           may become outdated, when servers change, therefore it is good
           practice to use a root-hints file.

      hide-identity: <yes or no>
           If enabled id.server and hostname.bind queries are refused.

      identity: <string>
           Set the identity to report. If set to "", the default, then the
           hostname of the server is returned.

      hide-version: <yes or no>
           If enabled version.server and version.bind queries are refused.

      version: <string>
           Set the version to report. If set to "", the default, then the
           package version is returned.

      hide-trustanchor: <yes or no>
           If enabled trustanchor.unbound queries are refused.



                                   - 16 -           Formatted:  June 4, 2020






 unbound.conf(5)                 NLnet Labs                  unbound.conf(5)
 unbound 1.10.1                                               unbound 1.10.1

                                May 19, 2020



      target-fetch-policy: <"list of numbers">
           Set the target fetch policy used by unbound to determine if it
           should fetch nameserver target addresses opportunistically. The
           policy is described per dependency depth.

           The number of values determines the maximum dependency depth that
           unbound will pursue in answering a query.  A value of -1 means to
           fetch all targets opportunistically for that dependency depth. A
           value of 0 means to fetch on demand only. A positive value
           fetches that many targets opportunistically.

           Enclose the list between quotes ("") and put spaces between
           numbers.  The default is "3 2 1 0 0". Setting all zeroes, "0 0 0
           0 0" gives behaviour closer to that of BIND 9, while setting "-1
           -1 -1 -1 -1" gives behaviour rumoured to be closer to that of
           BIND 8.

      harden-short-bufsize: <yes or no>
           Very small EDNS buffer sizes from queries are ignored. Default is
           off, since it is legal protocol wise to send these, and unbound
           tries to give very small answers to these queries, where
           possible.

      harden-large-queries: <yes or no>
           Very large queries are ignored. Default is off, since it is legal
           protocol wise to send these, and could be necessary for operation
           if TSIG or EDNS payload is very large.

      harden-glue: <yes or no>
           Will trust glue only if it is within the servers authority.
           Default is yes.

      harden-dnssec-stripped: <yes or no>
           Require DNSSEC data for trust-anchored zones, if such data is
           absent, the zone becomes bogus. If turned off, and no DNSSEC data
           is received (or the DNSKEY data fails to validate), then the zone
           is made insecure, this behaves like there is no trust anchor. You
           could turn this off if you are sometimes behind an intrusive
           firewall (of some sort) that removes DNSSEC data from packets, or
           a zone changes from signed to unsigned to badly signed often. If
           turned off you run the risk of a downgrade attack that disables
           security for a zone. Default is yes.

      harden-below-nxdomain: <yes or no>
           From RFC 8020 (with title "NXDOMAIN: There Really Is Nothing
           Underneath"), returns nxdomain to queries for a name below
           another name that is already known to be nxdomain.  DNSSEC
           mandates noerror for empty nonterminals, hence this is possible.
           Very old software might return nxdomain for empty nonterminals



                                   - 17 -           Formatted:  June 4, 2020






 unbound.conf(5)                 NLnet Labs                  unbound.conf(5)
 unbound 1.10.1                                               unbound 1.10.1

                                May 19, 2020



           (that usually happen for reverse IP address lookups), and thus
           may be incompatible with this.  To try to avoid this only
           DNSSEC-secure nxdomains are used, because the old software does
           not have DNSSEC.  Default is yes.  The nxdomain must be secure,
           this means nsec3 with optout is insufficient.

      harden-referral-path: <yes or no>
           Harden the referral path by performing additional queries for
           infrastructure data.  Validates the replies if trust anchors are
           configured and the zones are signed.  This enforces DNSSEC
           validation on nameserver NS sets and the nameserver addresses
           that are encountered on the referral path to the answer.  Default
           no, because it burdens the authority servers, and it is not RFC
           standard, and could lead to performance problems because of the
           extra query load that is generated.  Experimental option.  If you
           enable it consider adding more numbers after the
           target-fetch-policy to increase the max depth that is checked to.

      harden-algo-downgrade: <yes or no>
           Harden against algorithm downgrade when multiple algorithms are
           advertised in the DS record.  If no, allows the weakest algorithm
           to validate the zone.  Default is no.  Zone signers must produce
           zones that allow this feature to work, but sometimes they do not,
           and turning this option off avoids that validation failure.

      use-caps-for-id: <yes or no>
           Use 0x20-encoded random bits in the query to foil spoof attempts.
           This perturbs the lowercase and uppercase of query names sent to
           authority servers and checks if the reply still has the correct
           casing.  Disabled by default.  This feature is an experimental
           implementation of draft dns-0x20.

      caps-whitelist: <domain>
           Whitelist the domain so that it does not receive caps-for-id
           perturbed queries.  For domains that do not support 0x20 and also
           fail with fallback because they keep sending different answers,
           like some load balancers.  Can be given multiple times, for
           different domains.

      qname-minimisation: <yes or no>
           Send minimum amount of information to upstream servers to enhance
           privacy.  Only send minimum required labels of the QNAME and set
           QTYPE to A when possible. Best effort approach; full QNAME and
           original QTYPE will be sent when upstream replies with a RCODE
           other than NOERROR, except when receiving NXDOMAIN from a DNSSEC
           signed zone. Default is yes.

      qname-minimisation-strict: <yes or no>
           QNAME minimisation in strict mode. Do not fall-back to sending



                                   - 18 -           Formatted:  June 4, 2020






 unbound.conf(5)                 NLnet Labs                  unbound.conf(5)
 unbound 1.10.1                                               unbound 1.10.1

                                May 19, 2020



           full QNAME to potentially broken nameservers. A lot of domains
           will not be resolvable when this option in enabled. Only use if
           you know what you are doing.  This option only has effect when
           qname-minimisation is enabled. Default is off.

      aggressive-nsec: <yes or no>
           Aggressive NSEC uses the DNSSEC NSEC chain to synthesize NXDOMAIN
           and other denials, using information from previous NXDOMAINs
           answers.  Default is no.  It helps to reduce the query rate
           towards targets that get a very high nonexistent name lookup
           rate.

      private-address: <IP address or subnet>
           Give IPv4 of IPv6 addresses or classless subnets. These are
           addresses on your private network, and are not allowed to be
           returned for public internet names.  Any occurrence of such
           addresses are removed from DNS answers. Additionally, the DNSSEC
           validator may mark the answers bogus. This protects against
           so-called DNS Rebinding, where a user browser is turned into a
           network proxy, allowing remote access through the browser to
           other parts of your private network.  Some names can be allowed
           to contain your private addresses, by default all the local-data
           that you configured is allowed to, and you can specify additional
           names using private-domain.  No private addresses are enabled by
           default.  We consider to enable this for the RFC1918 private IP
           address space by default in later releases. That would enable
           private addresses for 10.0.0.0/8 172.16.0.0/12 192.168.0.0/16
           169.254.0.0/16 fd00::/8 and fe80::/10, since the RFC standards
           say these addresses should not be visible on the public internet.
           Turning on 127.0.0.0/8 would hinder many spamblocklists as they
           use that.  Adding ::ffff:0:0/96 stops IPv4-mapped IPv6 addresses
           from bypassing the filter.

      private-domain: <domain name>
           Allow this domain, and all its subdomains to contain private
           addresses.  Give multiple times to allow multiple domain names to
           contain private addresses. Default is none.

      unwanted-reply-threshold: <number>
           If set, a total number of unwanted replies is kept track of in
           every thread.  When it reaches the threshold, a defensive action
           is taken and a warning is printed to the log.  The defensive
           action is to clear the rrset and message caches, hopefully
           flushing away any poison.  A value of 10 million is suggested.
           Default is 0 (turned off).

      do-not-query-address: <IP address>
           Do not query the given IP address. Can be IP4 or IP6. Append /num
           to indicate a classless delegation netblock, for example like



                                   - 19 -           Formatted:  June 4, 2020






 unbound.conf(5)                 NLnet Labs                  unbound.conf(5)
 unbound 1.10.1                                               unbound 1.10.1

                                May 19, 2020



           10.2.3.4/24 or 2001::11/64.

      do-not-query-localhost: <yes or no>
           If yes, localhost is added to the do-not-query-address entries,
           both IP6 ::1 and IP4 127.0.0.1/8. If no, then localhost can be
           used to send queries to. Default is yes.

      prefetch: <yes or no>
           If yes, message cache elements are prefetched before they expire
           to keep the cache up to date.  Default is no.  Turning it on
           gives about 10 percent more traffic and load on the machine, but
           popular items do not expire from the cache.

      prefetch-key: <yes or no>
           If yes, fetch the DNSKEYs earlier in the validation process, when
           a DS record is encountered.  This lowers the latency of requests.
           It does use a little more CPU.  Also if the cache is set to 0, it
           is no use. Default is no.

      deny-any: <yes or no>
           If yes, deny queries of type ANY with an empty response.  Default
           is no.  If disabled, unbound responds with a short list of
           resource records if some can be found in the cache and makes the
           upstream type ANY query if there are none.

      rrset-roundrobin: <yes or no>
           If yes, Unbound rotates RRSet order in response (the random
           number is taken from the query ID, for speed and thread safety).
           Default is no.

      minimal-responses: <yes or no>
           If yes, Unbound doesn't insert authority/additional sections into
           response messages when those sections are not required.  This
           reduces response size significantly, and may avoid TCP fallback
           for some responses.  This may cause a slight speedup.  The
           default is yes, even though the DNS protocol RFCs mandate these
           sections, and the additional content could be of use and save
           roundtrips for clients.  Because they are not used, and the saved
           roundtrips are easier saved with prefetch, whilst this is faster.

      disable-dnssec-lame-check: <yes or no>
           If true, disables the DNSSEC lameness check in the iterator.
           This check sees if RRSIGs are present in the answer, when dnssec
           is expected, and retries another authority if RRSIGs are
           unexpectedly missing.  The validator will insist in RRSIGs for
           DNSSEC signed domains regardless of this setting, if a trust
           anchor is loaded.

      module-config: <"module names">



                                   - 20 -           Formatted:  June 4, 2020






 unbound.conf(5)                 NLnet Labs                  unbound.conf(5)
 unbound 1.10.1                                               unbound 1.10.1

                                May 19, 2020



           Module configuration, a list of module names separated by spaces,
           surround the string with quotes (""). The modules can be
           validator, iterator.  Setting this to "iterator" will result in a
           non-validating server.  Setting this to "validator iterator" will
           turn on DNSSEC validation.  The ordering of the modules is
           important.  You must also set trust-anchors for validation to be
           useful.  The default is "validator iterator".  When the server is
           built with EDNS client subnet support the default is "subnetcache
           validator iterator".  Most modules that need to be listed here
           have to be listed at the beginning of the line.  The cachedb
           module has to be listed just before the iterator.  The python
           module can be listed in different places, it then processes the
           output of the module it is just before.

      trust-anchor-file: <filename>
           File with trusted keys for validation. Both DS and DNSKEY entries
           can appear in the file. The format of the file is the standard
           DNS Zone file format.  Default is "", or no trust anchor file.

      auto-trust-anchor-file: <filename>
           File with trust anchor for one zone, which is tracked with
           RFC5011 probes.  The probes are run several times per month, thus
           the machine must be online frequently.  The initial file can be
           one with contents as described in trust-anchor-file.  The file is
           written to when the anchor is updated, so the unbound user must
           have write permission.  Write permission to the file, but also to
           the directory it is in (to create a temporary file, which is
           necessary to deal with filesystem full events), it must also be
           inside the chroot (if that is used).

      trust-anchor: <"Resource Record">
           A DS or DNSKEY RR for a key to use for validation. Multiple
           entries can be given to specify multiple trusted keys, in
           addition to the trust-anchor-files.  The resource record is
           entered in the same format as 'dig' or 'drill' prints them, the
           same format as in the zone file. Has to be on a single line, with
           "" around it. A TTL can be specified for ease of cut and paste,
           but is ignored.  A class can be specified, but class IN is
           default.

      trusted-keys-file: <filename>
           File with trusted keys for validation. Specify more than one file
           with several entries, one file per entry. Like trust-anchor-file
           but has a different file format. Format is BIND-9 style format,
           the trusted-keys { name flag proto algo "key"; }; clauses are
           read.  It is possible to use wildcards with this statement, the
           wildcard is expanded on start and on reload.

      trust-anchor-signaling: <yes or no>



                                   - 21 -           Formatted:  June 4, 2020






 unbound.conf(5)                 NLnet Labs                  unbound.conf(5)
 unbound 1.10.1                                               unbound 1.10.1

                                May 19, 2020



           Send RFC8145 key tag query after trust anchor priming. Default is
           yes.

      root-key-sentinel: <yes or no>
           Root key trust anchor sentinel. Default is yes.

      dlv-anchor-file: <filename>
           This option was used during early days DNSSEC deployment when no
           parent-side DS record registrations were easily available.
           Nowadays, it is best to have DS records registered with the
           parent zone (many top level zones are signed).  File with trusted
           keys for DLV (DNSSEC Lookaside Validation). Both DS and DNSKEY
           entries can be used in the file, in the same format as for
           trust-anchor-file: statements. Only one DLV can be configured,
           more would be slow. The DLV configured is used as a root trusted
           DLV, this means that it is a lookaside for the root. Default is
           "", or no dlv anchor file. DLV is going to be decommissioned.
           Please do not use it any more.

      dlv-anchor: <"Resource Record">
           Much like trust-anchor, this is a DLV anchor with the DS or
           DNSKEY inline.  DLV is going to be decommissioned.  Please do not
           use it any more.

      domain-insecure: <domain name>
           Sets domain name to be insecure, DNSSEC chain of trust is ignored
           towards the domain name.  So a trust anchor above the domain name
           can not make the domain secure with a DS record, such a DS record
           is then ignored.  Also keys from DLV are ignored for the domain.
           Can be given multiple times to specify multiple domains that are
           treated as if unsigned.  If you set trust anchors for the domain
           they override this setting (and the domain is secured).

           This can be useful if you want to make sure a trust anchor for
           external lookups does not affect an (unsigned) internal domain.
           A DS record externally can create validation failures for that
           internal domain.

      val-override-date: <rrsig-style date spec>
           Default is "" or "0", which disables this debugging feature. If
           enabled by giving a RRSIG style date, that date is used for
           verifying RRSIG inception and expiration dates, instead of the
           current date. Do not set this unless you are debugging signature
           inception and expiration. The value -1 ignores the date
           altogether, useful for some special applications.

      val-sig-skew-min: <seconds>
           Minimum number of seconds of clock skew to apply to validated
           signatures.  A value of 10% of the signature lifetime (expiration



                                   - 22 -           Formatted:  June 4, 2020






 unbound.conf(5)                 NLnet Labs                  unbound.conf(5)
 unbound 1.10.1                                               unbound 1.10.1

                                May 19, 2020



           - inception) is used, capped by this setting.  Default is 3600 (1
           hour) which allows for daylight savings differences.  Lower this
           value for more strict checking of short lived signatures.

      val-sig-skew-max: <seconds>
           Maximum number of seconds of clock skew to apply to validated
           signatures.  A value of 10% of the signature lifetime (expiration
           - inception) is used, capped by this setting.  Default is 86400
           (24 hours) which allows for timezone setting problems in stable
           domains.  Setting both min and max very low disables the clock
           skew allowances.  Setting both min and max very high makes the
           validator check the signature timestamps less strictly.

      val-bogus-ttl: <number>
           The time to live for bogus data. This is data that has failed
           validation; due to invalid signatures or other checks. The TTL
           from that data cannot be trusted, and this value is used instead.
           The value is in seconds, default 60.  The time interval prevents
           repeated revalidation of bogus data.

      val-clean-additional: <yes or no>
           Instruct the validator to remove data from the additional section
           of secure messages that are not signed properly. Messages that
           are insecure, bogus, indeterminate or unchecked are not affected.
           Default is yes. Use this setting to protect the users that rely
           on this validator for authentication from potentially bad data in
           the additional section.

      val-log-level: <number>
           Have the validator print validation failures to the log.
           Regardless of the verbosity setting.  Default is 0, off.  At 1,
           for every user query that fails a line is printed to the logs.
           This way you can monitor what happens with validation.  Use a
           diagnosis tool, such as dig or drill, to find out why validation
           is failing for these queries.  At 2, not only the query that
           failed is printed but also the reason why unbound thought it was
           wrong and which server sent the faulty data.

      val-permissive-mode: <yes or no>
           Instruct the validator to mark bogus messages as indeterminate.
           The security checks are performed, but if the result is bogus
           (failed security), the reply is not withheld from the client with
           SERVFAIL as usual. The client receives the bogus data. For
           messages that are found to be secure the AD bit is set in
           replies. Also logging is performed as for full validation.  The
           default value is "no".

      ignore-cd-flag: <yes or no>
           Instruct unbound to ignore the CD flag from clients and refuse to



                                   - 23 -           Formatted:  June 4, 2020






 unbound.conf(5)                 NLnet Labs                  unbound.conf(5)
 unbound 1.10.1                                               unbound 1.10.1

                                May 19, 2020



           return bogus answers to them.  Thus, the CD (Checking Disabled)
           flag does not disable checking any more.  This is useful if
           legacy (w2008) servers that set the CD flag but cannot validate
           DNSSEC themselves are the clients, and then unbound provides them
           with DNSSEC protection.  The default value is "no".

      serve-expired: <yes or no>
           If enabled, unbound attempts to serve old responses from cache
           with a TTL of serve-expired-reply-ttl in the response without
           waiting for the actual resolution to finish.  The actual
           resolution answer ends up in the cache later on.  Default is
           "no".

      serve-expired-ttl: <seconds>
           Limit serving of expired responses to configured seconds after
           expiration. 0 disables the limit.  This option only applies when
           serve-expired is enabled.  A suggested value per draft-ietf-
           dnsop-serve-stale-10 is between 86400 (1 day) and 259200 (3
           days).  The default is 0.

      serve-expired-ttl-reset: <yes or no>
           Set the TTL of expired records to the serve-expired-ttl value
           after a failed attempt to retrieve the record from upstream.
           This makes sure that the expired records will be served as long
           as there are queries for it.  Default is "no".

      serve-expired-reply-ttl: <seconds>
           TTL value to use when replying with expired data.  If
           serve-expired-client-timeout is also used then it is RECOMMENDED
           to use 30 as the value (draft-ietf-dnsop-serve-stale-10).  The
           default is 30.

      serve-expired-client-timeout: <msec>
           Time in milliseconds before replying to the client with expired
           data.  This essentially enables the serve-stale behavior as
           specified in draft-ietf-dnsop-serve-stale-10 that first tries to
           resolve before immediately responding with expired data.  A
           recommended value per draft-ietf-dnsop-serve-stale-10 is 1800.
           Setting this to 0 will disable this behavior.  Default is 0.

      val-nsec3-keysize-iterations: <"list of values">
           List of keysize and iteration count values, separated by spaces,
           surrounded by quotes. Default is "1024 150 2048 500 4096 2500".
           This determines the maximum allowed NSEC3 iteration count before
           a message is simply marked insecure instead of performing the
           many hashing iterations. The list must be in ascending order and
           have at least one entry. If you set it to "1024 65535" there is
           no restriction to NSEC3 iteration values.  This table must be
           kept short; a very long list could cause slower operation.



                                   - 24 -           Formatted:  June 4, 2020






 unbound.conf(5)                 NLnet Labs                  unbound.conf(5)
 unbound 1.10.1                                               unbound 1.10.1

                                May 19, 2020



      add-holddown: <seconds>
           Instruct the auto-trust-anchor-file probe mechanism for RFC5011
           autotrust updates to add new trust anchors only after they have
           been visible for this time.  Default is 30 days as per the RFC.

      del-holddown: <seconds>
           Instruct the auto-trust-anchor-file probe mechanism for RFC5011
           autotrust updates to remove revoked trust anchors after they have
           been kept in the revoked list for this long.  Default is 30 days
           as per the RFC.

      keep-missing: <seconds>
           Instruct the auto-trust-anchor-file probe mechanism for RFC5011
           autotrust updates to remove missing trust anchors after they have
           been unseen for this long.  This cleans up the state file if the
           target zone does not perform trust anchor revocation, so this
           makes the auto probe mechanism work with zones that perform
           regular (non-5011) rollovers.  The default is 366 days.  The
           value 0 does not remove missing anchors, as per the RFC.

      permit-small-holddown: <yes or no>
           Debug option that allows the autotrust 5011 rollover timers to
           assume very small values.  Default is no.

      key-cache-size: <number>
           Number of bytes size of the key cache. Default is 4 megabytes.  A
           plain number is in bytes, append 'k', 'm' or 'g' for kilobytes,
           megabytes or gigabytes (1024*1024 bytes in a megabyte).

      key-cache-slabs: <number>
           Number of slabs in the key cache. Slabs reduce lock contention by
           threads.  Must be set to a power of 2. Setting (close) to the
           number of cpus is a reasonable guess.

      neg-cache-size: <number>
           Number of bytes size of the aggressive negative cache. Default is
           1 megabyte.  A plain number is in bytes, append 'k', 'm' or 'g'
           for kilobytes, megabytes or gigabytes (1024*1024 bytes in a
           megabyte).

      unblock-lan-zones: <yes or no>
           Default is disabled.  If enabled, then for private address space,
           the reverse lookups are no longer filtered.  This allows unbound
           when running as dns service on a host where it provides service
           for that host, to put out all of the queries for the 'lan'
           upstream.  When enabled, only localhost, 127.0.0.1 reverse and
           ::1 reverse zones are configured with default local zones.
           Disable the option when unbound is running as a (DHCP-) DNS
           network resolver for a group of machines, where such lookups



                                   - 25 -           Formatted:  June 4, 2020






 unbound.conf(5)                 NLnet Labs                  unbound.conf(5)
 unbound 1.10.1                                               unbound 1.10.1

                                May 19, 2020



           should be filtered (RFC compliance), this also stops potential
           data leakage about the local network to the upstream DNS servers.

      insecure-lan-zones: <yes or no>
           Default is disabled.  If enabled, then reverse lookups in private
           address space are not validated.  This is usually required
           whenever unblock-lan-zones is used.

      local-zone: <zone> <type>
           Configure a local zone. The type determines the answer to give if
           there is no match from local-data. The types are deny, refuse,
           static, transparent, redirect, nodefault, typetransparent,
           inform, inform_deny, inform_redirect, always_transparent,
           always_refuse, always_nxdomain, noview, and are explained below.
           After that the default settings are listed. Use local-data: to
           enter data into the local zone. Answers for local zones are
           authoritative DNS answers. By default the zones are class IN.

           If you need more complicated authoritative data, with referrals,
           wildcards, CNAME/DNAME support, or DNSSEC authoritative service,
           setup a stub-zone for it as detailed in the stub zone section
           below.

           deny Do not send an answer, drop the query.  If there is a match
                from local data, the query is answered.

           refuse
                Send an error message reply, with rcode REFUSED.  If there
                is a match from local data, the query is answered.

           static
                If there is a match from local data, the query is answered.
                Otherwise, the query is answered with nodata or nxdomain.
                For a negative answer a SOA is included in the answer if
                present as local-data for the zone apex domain.

           transparent
                If there is a match from local data, the query is answered.
                Otherwise if the query has a different name, the query is
                resolved normally.  If the query is for a name given in
                localdata but no such type of data is given in localdata,
                then a noerror nodata answer is returned.  If no local-zone
                is given local-data causes a transparent zone to be created
                by default.

           typetransparent
                If there is a match from local data, the query is answered.
                If the query is for a different name, or for the same name
                but for a different type, the query is resolved normally.



                                   - 26 -           Formatted:  June 4, 2020






 unbound.conf(5)                 NLnet Labs                  unbound.conf(5)
 unbound 1.10.1                                               unbound 1.10.1

                                May 19, 2020



                So, similar to transparent but types that are not listed in
                local data are resolved normally, so if an A record is in
                the local data that does not cause a nodata reply for AAAA
                queries.

           redirect
                The query is answered from the local data for the zone name.
                There may be no local data beneath the zone name.  This
                answers queries for the zone, and all subdomains of the zone
                with the local data for the zone.  It can be used to
                redirect a domain to return a different address record to
                the end user, with local-zone: "example.com." redirect and
                local-data: "example.com. A 127.0.0.1" queries for
                www.example.com and www.foo.example.com are redirected, so
                that users with web browsers cannot access sites with suffix
                example.com.

           inform
                The query is answered normally, same as transparent.  The
                client IP address (@portnumber) is printed to the logfile.
                The log message is: timestamp, unbound-pid, info: zonename
                inform IP@port queryname type class.  This option can be
                used for normal resolution, but machines looking up infected
                names are logged, eg. to run antivirus on them.

           inform_deny
                The query is dropped, like 'deny', and logged, like
                'inform'.  Ie. find infected machines without answering the
                queries.

           inform_redirect
                The query is redirected, like 'redirect', and logged, like
                'inform'.  Ie. answer queries with fixed data and also log
                the machines that ask.

           always_transparent
                Like transparent, but ignores local data and resolves
                normally.

           always_refuse
                Like refuse, but ignores local data and refuses the query.

           always_nxdomain
                Like static, but ignores local data and returns nxdomain for
                the query.

           noview
                Breaks out of that view and moves towards the global local
                zones for answer to the query.  If the view first is no,



                                   - 27 -           Formatted:  June 4, 2020






 unbound.conf(5)                 NLnet Labs                  unbound.conf(5)
 unbound 1.10.1                                               unbound 1.10.1

                                May 19, 2020



                it'll resolve normally.  If view first is enabled, it'll
                break perform that step and check the global answers.  For
                when the view has view specific overrides but some zone has
                to be answered from global local zone contents.

           nodefault
                Used to turn off default contents for AS112 zones. The other
                types also turn off default contents for the zone. The
                'nodefault' option has no other effect than turning off
                default contents for the given zone.  Use nodefault if you
                use exactly that zone, if you want to use a subzone, use
                transparent.

      The default zones are localhost, reverse 127.0.0.1 and ::1, the onion,
      test, invalid and the AS112 zones. The AS112 zones are reverse DNS
      zones for private use and reserved IP addresses for which the servers
      on the internet cannot provide correct answers. They are configured by
      default to give nxdomain (no reverse information) answers. The
      defaults can be turned off by specifying your own local-zone of that
      name, or using the 'nodefault' type. Below is a list of the default
      zone contents.

           localhost
                The IP4 and IP6 localhost information is given. NS and SOA
                records are provided for completeness and to satisfy some
                DNS update tools. Default content:
                local-zone: "localhost." redirect
                local-data: "localhost. 10800 IN NS localhost."
                local-data: "localhost. 10800 IN
                    SOA localhost. nobody.invalid. 1 3600 1200 604800 10800"
                local-data: "localhost. 10800 IN A 127.0.0.1"
                local-data: "localhost. 10800 IN AAAA ::1"

           reverse IPv4 loopback
                Default content:
                local-zone: "127.in-addr.arpa." static
                local-data: "127.in-addr.arpa. 10800 IN NS localhost."
                local-data: "127.in-addr.arpa. 10800 IN
                    SOA localhost. nobody.invalid. 1 3600 1200 604800 10800"
                local-data: "1.0.0.127.in-addr.arpa. 10800 IN
                    PTR localhost."

           reverse IPv6 loopback
                Default content:
                local-zone: "1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.
                    0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.ip6.arpa." static
                local-data: "1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.
                    0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.ip6.arpa. 10800 IN
                    NS localhost."



                                   - 28 -           Formatted:  June 4, 2020






 unbound.conf(5)                 NLnet Labs                  unbound.conf(5)
 unbound 1.10.1                                               unbound 1.10.1

                                May 19, 2020



                local-data: "1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.
                    0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.ip6.arpa. 10800 IN
                    SOA localhost. nobody.invalid. 1 3600 1200 604800 10800"
                local-data: "1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.
                    0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.ip6.arpa. 10800 IN
                    PTR localhost."

           onion (RFC 7686)
                Default content:
                local-zone: "onion." static
                local-data: "onion. 10800 IN NS localhost."
                local-data: "onion. 10800 IN
                    SOA localhost. nobody.invalid. 1 3600 1200 604800 10800"

           test (RFC 6761)
                Default content:
                local-zone: "test." static
                local-data: "test. 10800 IN NS localhost."
                local-data: "test. 10800 IN
                    SOA localhost. nobody.invalid. 1 3600 1200 604800 10800"

           invalid (RFC 6761)
                Default content:
                local-zone: "invalid." static
                local-data: "invalid. 10800 IN NS localhost."
                local-data: "invalid. 10800 IN
                    SOA localhost. nobody.invalid. 1 3600 1200 604800 10800"

           reverse RFC1918 local use zones
                Reverse data for zones 10.in-addr.arpa, 16.172.in-addr.arpa
                to 31.172.in-addr.arpa, 168.192.in-addr.arpa.  The
                local-zone: is set static and as local-data: SOA and NS
                records are provided.

           reverse RFC3330 IP4 this, link-local, testnet and broadcast
                Reverse data for zones 0.in-addr.arpa, 254.169.in-addr.arpa,
                2.0.192.in-addr.arpa (TEST NET 1), 100.51.198.in-addr.arpa
                (TEST NET 2), 113.0.203.in-addr.arpa (TEST NET 3),
                255.255.255.255.in-addr.arpa.  And from 64.100.in-addr.arpa
                to 127.100.in-addr.arpa (Shared Address Space).

           reverse RFC4291 IP6 unspecified
                Reverse data for zone
                0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.
                0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.ip6.arpa.

           reverse RFC4193 IPv6 Locally Assigned Local Addresses
                Reverse data for zone D.F.ip6.arpa.




                                   - 29 -           Formatted:  June 4, 2020






 unbound.conf(5)                 NLnet Labs                  unbound.conf(5)
 unbound 1.10.1                                               unbound 1.10.1

                                May 19, 2020



           reverse RFC4291 IPv6 Link Local Addresses
                Reverse data for zones 8.E.F.ip6.arpa to B.E.F.ip6.arpa.

           reverse IPv6 Example Prefix
                Reverse data for zone 8.B.D.0.1.0.0.2.ip6.arpa. This zone is
                used for tutorials and examples. You can remove the block on
                this zone with:
                  local-zone: 8.B.D.0.1.0.0.2.ip6.arpa. nodefault
                You can also selectively unblock a part of the zone by
                making that part transparent with a local-zone statement.
                This also works with the other default zones.

      local-data: "<resource record string>"
           Configure local data, which is served in reply to queries for it.
           The query has to match exactly unless you configure the
           local-zone as redirect. If not matched exactly, the local-zone
           type determines further processing. If local-data is configured
           that is not a subdomain of a local-zone, a transparent local-zone
           is configured.  For record types such as TXT, use single quotes,
           as in local-data: 'example. TXT "text"'.

           If you need more complicated authoritative data, with referrals,
           wildcards, CNAME/DNAME support, or DNSSEC authoritative service,
           setup a stub-zone for it as detailed in the stub zone section
           below.

      local-data-ptr: "IPaddr name"
           Configure local data shorthand for a PTR record with the reversed
           IPv4 or IPv6 address and the host name.  For example "192.0.2.4
           www.example.com".  TTL can be inserted like this: "2001:DB8::4
           7200 www.example.com"

      local-zone-tag: <zone> <"list of tags">
           Assign tags to localzones. Tagged localzones will only be applied
           when the used access-control element has a matching tag. Tags
           must be defined in define-tags.  Enclose list of tags in quotes
           ("") and put spaces between tags.  When there are multiple tags
           it checks if the intersection of the list of tags for the query
           and local-zone-tag is non-empty.

      local-zone-override: <zone> <IP netblock> <type>
           Override the localzone type for queries from addresses matching
           netblock.  Use this localzone type, regardless the type
           configured for the local-zone (both tagged and untagged) and
           regardless the type configured using access-control-tag-action.

      ratelimit: <number or 0>
           Enable ratelimiting of queries sent to nameserver for performing
           recursion.  If 0, the default, it is disabled.  This option is



                                   - 30 -           Formatted:  June 4, 2020






 unbound.conf(5)                 NLnet Labs                  unbound.conf(5)
 unbound 1.10.1                                               unbound 1.10.1

                                May 19, 2020



           experimental at this time.  The ratelimit is in queries per
           second that are allowed.  More queries are turned away with an
           error (servfail).  This stops recursive floods, eg. random query
           names, but not spoofed reflection floods.  Cached responses are
           not ratelimited by this setting.  The zone of the query is
           determined by examining the nameservers for it, the zone name is
           used to keep track of the rate.  For example, 1000 may be a
           suitable value to stop the server from being overloaded with
           random names, and keeps unbound from sending traffic to the
           nameservers for those zones.

      ratelimit-size: <memory size>
           Give the size of the data structure in which the current ongoing
           rates are kept track in.  Default 4m.  In bytes or use m(mega),
           k(kilo), g(giga).  The ratelimit structure is small, so this data
           structure likely does not need to be large.

      ratelimit-slabs: <number>
           Give power of 2 number of slabs, this is used to reduce lock
           contention in the ratelimit tracking data structure.  Close to
           the number of cpus is a fairly good setting.

      ratelimit-factor: <number>
           Set the amount of queries to rate limit when the limit is
           exceeded.  If set to 0, all queries are dropped for domains where
           the limit is exceeded.  If set to another value, 1 in that number
           is allowed through to complete.  Default is 10, allowing 1/10
           traffic to flow normally.  This can make ordinary queries
           complete (if repeatedly queried for), and enter the cache, whilst
           also mitigating the traffic flow by the factor given.

      ratelimit-for-domain: <domain> <number qps or 0>
           Override the global ratelimit for an exact match domain name with
           the listed number.  You can give this for any number of names.
           For example, for a top-level-domain you may want to have a higher
           limit than other names.  A value of 0 will disable ratelimiting
           for that domain.

      ratelimit-below-domain: <domain> <number qps or 0>
           Override the global ratelimit for a domain name that ends in this
           name.  You can give this multiple times, it then describes
           different settings in different parts of the namespace.  The
           closest matching suffix is used to determine the qps limit.  The
           rate for the exact matching domain name is not changed, use
           ratelimit-for-domain to set that, you might want to use different
           settings for a top-level-domain and subdomains.  A value of 0
           will disable ratelimiting for domain names that end in this name.

      ip-ratelimit: <number or 0>



                                   - 31 -           Formatted:  June 4, 2020






 unbound.conf(5)                 NLnet Labs                  unbound.conf(5)
 unbound 1.10.1                                               unbound 1.10.1

                                May 19, 2020



           Enable global ratelimiting of queries accepted per ip address.
           If 0, the default, it is disabled.  This option is experimental
           at this time.  The ratelimit is in queries per second that are
           allowed.  More queries are completely dropped and will not
           receive a reply, SERVFAIL or otherwise.  IP ratelimiting happens
           before looking in the cache. This may be useful for mitigating
           amplification attacks.

      ip-ratelimit-size: <memory size>
           Give the size of the data structure in which the current ongoing
           rates are kept track in.  Default 4m.  In bytes or use m(mega),
           k(kilo), g(giga).  The ip ratelimit structure is small, so this
           data structure likely does not need to be large.

      ip-ratelimit-slabs: <number>
           Give power of 2 number of slabs, this is used to reduce lock
           contention in the ip ratelimit tracking data structure.  Close to
           the number of cpus is a fairly good setting.

      ip-ratelimit-factor: <number>
           Set the amount of queries to rate limit when the limit is
           exceeded.  If set to 0, all queries are dropped for addresses
           where the limit is exceeded.  If set to another value, 1 in that
           number is allowed through to complete.  Default is 10, allowing
           1/10 traffic to flow normally.  This can make ordinary queries
           complete (if repeatedly queried for), and enter the cache, whilst
           also mitigating the traffic flow by the factor given.

      fast-server-permil: <number>
           Specify how many times out of 1000 to pick from the set of
           fastest servers.  0 turns the feature off.  A value of 900 would
           pick from the fastest servers 90 percent of the time, and would
           perform normal exploration of random servers for the remaining
           time. When prefetch is enabled (or serve-expired), such
           prefetches are not sped up, because there is no one waiting for
           it, and it presents a good moment to perform server exploration.
           The fast-server-num option can be used to specify the size of the
           fastest servers set. The default for fast-server-permil is 0.

      fast-server-num: <number>
           Set the number of servers that should be used for fast server
           selection. Only use the fastest specified number of servers with
           the fast-server-permil option, that turns this on or off. The
           default is to use the fastest 3 servers.

    Remote Control Options
      In the remote-control: clause are the declarations for the remote
      control facility.  If this is enabled, the unbound-control(8) utility
      can be used to send commands to the running unbound server.  The



                                   - 32 -           Formatted:  June 4, 2020






 unbound.conf(5)                 NLnet Labs                  unbound.conf(5)
 unbound 1.10.1                                               unbound 1.10.1

                                May 19, 2020



      server uses these clauses to setup TLSv1 security for the connection.
      The unbound-control(8) utility also reads the remote-control section
      for options.  To setup the correct self-signed certificates use the
      unbound-control-setup(8) utility.

      control-enable: <yes or no>
           The option is used to enable remote control, default is "no".  If
           turned off, the server does not listen for control commands.

      control-interface: <ip address or path>
           Give IPv4 or IPv6 addresses or local socket path to listen on for
           control commands.  By default localhost (127.0.0.1 and ::1) is
           listened to.  Use 0.0.0.0 and ::0 to listen to all interfaces.
           If you change this and permissions have been dropped, you must
           restart the server for the change to take effect.

           If you set it to an absolute path, a local socket is used.  The
           local socket does not use the certificates and keys, so those
           files need not be present.  To restrict access, unbound sets
           permissions on the file to the user and group that is configured,
           the access bits are set to allow the group members to access the
           control socket file.  Put users that need to access the socket in
           the that group.  To restrict access further, create a directory
           to put the control socket in and restrict access to that
           directory.

      control-port: <port number>
           The port number to listen on for IPv4 or IPv6 control interfaces,
           default is 8953.  If you change this and permissions have been
           dropped, you must restart the server for the change to take
           effect.

      control-use-cert: <yes or no>
           For localhost control-interface you can disable the use of TLS by
           setting this option to "no", default is "yes".  For local
           sockets, TLS is disabled and the value of this option is ignored.

      server-key-file: <private key file>
           Path to the server private key, by default unbound_server.key.
           This file is generated by the unbound-control-setup utility.
           This file is used by the unbound server, but not by
           unbound-control.

      server-cert-file: <certificate file.pem>
           Path to the server self signed certificate, by default
           unbound_server.pem.  This file is generated by the
           unbound-control-setup utility.  This file is used by the unbound
           server, and also by unbound-control.




                                   - 33 -           Formatted:  June 4, 2020






 unbound.conf(5)                 NLnet Labs                  unbound.conf(5)
 unbound 1.10.1                                               unbound 1.10.1

                                May 19, 2020



      control-key-file: <private key file>
           Path to the control client private key, by default
           unbound_control.key.  This file is generated by the
           unbound-control-setup utility.  This file is used by
           unbound-control.

      control-cert-file: <certificate file.pem>
           Path to the control client certificate, by default
           unbound_control.pem.  This certificate has to be signed with the
           server certificate.  This file is generated by the
           unbound-control-setup utility.  This file is used by
           unbound-control.

    Stub Zone Options
      There may be multiple stub-zone: clauses. Each with a name: and zero
      or more hostnames or IP addresses.  For the stub zone this list of
      nameservers is used. Class IN is assumed.  The servers should be
      authority servers, not recursors; unbound performs the recursive
      processing itself for stub zones.

      The stub zone can be used to configure authoritative data to be used
      by the resolver that cannot be accessed using the public internet
      servers.  This is useful for company-local data or private zones.
      Setup an authoritative server on a different host (or different port).
      Enter a config entry for unbound with stub-addr: <ip address of
      host[@port]>.  The unbound resolver can then access the data, without
      referring to the public internet for it.

      This setup allows DNSSEC signed zones to be served by that
      authoritative server, in which case a trusted key entry with the
      public key can be put in config, so that unbound can validate the data
      and set the AD bit on replies for the private zone (authoritative
      servers do not set the AD bit).  This setup makes unbound capable of
      answering queries for the private zone, and can even set the AD bit
      ('authentic'), but the AA ('authoritative') bit is not set on these
      replies.

      Consider adding server: statements for domain-insecure: and for
      local-zone: name nodefault for the zone if it is a locally served
      zone.  The insecure clause stops DNSSEC from invalidating the zone.
      The local zone nodefault (or transparent) clause makes the (reverse-)
      zone bypass unbound's filtering of RFC1918 zones.

      name: <domain name>
           Name of the stub zone.

      stub-host: <domain name>
           Name of stub zone nameserver. Is itself resolved before it is
           used.



                                   - 34 -           Formatted:  June 4, 2020






 unbound.conf(5)                 NLnet Labs                  unbound.conf(5)
 unbound 1.10.1                                               unbound 1.10.1

                                May 19, 2020



      stub-addr: <IP address>
           IP address of stub zone nameserver. Can be IP 4 or IP 6.  To use
           a nondefault port for DNS communication append '@' with the port
           number.

      stub-prime: <yes or no>
           This option is by default no.  If enabled it performs NS set
           priming, which is similar to root hints, where it starts using
           the list of nameservers currently published by the zone.  Thus,
           if the hint list is slightly outdated, the resolver picks up a
           correct list online.

      stub-first: <yes or no>
           If enabled, a query is attempted without the stub clause if it
           fails.  The data could not be retrieved and would have caused
           SERVFAIL because the servers are unreachable, instead it is tried
           without this clause.  The default is no.

      stub-tls-upstream: <yes or no>
           Enabled or disable whether the queries to this stub use TLS for
           transport.  Default is no.

      stub-ssl-upstream: <yes or no>
           Alternate syntax for stub-tls-upstream.

      stub-no-cache: <yes or no>
           Default is no.  If enabled, data inside the stub is not cached.
           This is useful when you want immediate changes to be visible.

    Forward Zone Options
      There may be multiple forward-zone: clauses. Each with a name: and
      zero or more hostnames or IP addresses.  For the forward zone this
      list of nameservers is used to forward the queries to. The servers
      listed as forward-host: and forward-addr: have to handle further
      recursion for the query.  Thus, those servers are not authority
      servers, but are (just like unbound is) recursive servers too; unbound
      does not perform recursion itself for the forward zone, it lets the
      remote server do it.  Class IN is assumed.  CNAMEs are chased by
      unbound itself, asking the remote server for every name in the
      indirection chain, to protect the local cache from illegal indirect
      referenced items.  A forward-zone entry with name "." and a
      forward-addr target will forward all queries to that other server
      (unless it can answer from the cache).

      name: <domain name>
           Name of the forward zone.

      forward-host: <domain name>
           Name of server to forward to. Is itself resolved before it is



                                   - 35 -           Formatted:  June 4, 2020






 unbound.conf(5)                 NLnet Labs                  unbound.conf(5)
 unbound 1.10.1                                               unbound 1.10.1

                                May 19, 2020



           used.

      forward-addr: <IP address>
           IP address of server to forward to. Can be IP 4 or IP 6.  To use
           a nondefault port for DNS communication append '@' with the port
           number.  If tls is enabled, then you can append a '#' and a name,
           then it'll check the tls authentication certificates with that
           name.  If you combine the '@' and '#', the '@' comes first.

           At high verbosity it logs the TLS certificate, with TLS enabled.
           If you leave out the '#' and auth name from the forward-addr, any
           name is accepted.  The cert must also match a CA from the
           tls-cert-bundle.

      forward-first: <yes or no>
           If a forwarded query is met with a SERVFAIL error, and this
           option is enabled, unbound will fall back to normal recursive
           resolution for this query as if no query forwarding had been
           specified.  The default is "no".

      forward-tls-upstream: <yes or no>
           Enabled or disable whether the queries to this forwarder use TLS
           for transport.  Default is no.  If you enable this, also
           configure a tls-cert-bundle or use tls-win-cert to load CA certs,
           otherwise the connections cannot be authenticated.

      forward-ssl-upstream: <yes or no>
           Alternate syntax for forward-tls-upstream.

      forward-no-cache: <yes or no>
           Default is no.  If enabled, data inside the forward is not
           cached.  This is useful when you want immediate changes to be
           visible.

    Authority Zone Options
      Authority zones are configured with auth-zone:, and each one must have
      a name:.  There can be multiple ones, by listing multiple auth-zone
      clauses, each with a different name, pertaining to that part of the
      namespace.  The authority zone with the name closest to the name
      looked up is used.  Authority zones are processed after local-zones
      and before cache (for-downstream: yes), and when used in this manner
      make unbound respond like an authority server.  Authority zones are
      also processed after cache, just before going to the network to fetch
      information for recursion (for-upstream: yes), and when used in this
      manner provide a local copy of an authority server that speeds up
      lookups of that data.  Authority zones can be read from zonefile.  And
      can be kept updated via AXFR and IXFR.  After update the zonefile is
      rewritten.  The update mechanism uses the SOA timer values and
      performs SOA UDP queries to detect zone changes.  If the update fetch



                                   - 36 -           Formatted:  June 4, 2020






 unbound.conf(5)                 NLnet Labs                  unbound.conf(5)
 unbound 1.10.1                                               unbound 1.10.1

                                May 19, 2020



      fails, the timers in the SOA record are used to time another fetch
      attempt.  Until the SOA expiry timer is reached.  Then the zone is
      expired.  When a zone is expired, queries are SERVFAIL, and any new
      serial number is accepted from the master (even if older), and if
      fallback is enabled, the fallback activates to fetch from the upstream
      instead of the SERVFAIL.

      name: <zone name>
           Name of the authority zone.

      master: <IP address or host name>
           Where to download a copy of the zone from, with AXFR and IXFR.
           Multiple masters can be specified.  They are all tried if one
           fails.  With the "ip#name" notation a AXFR over TLS can be used.
           If you point it at another Unbound instance, it would not work
           because that does not support AXFR/IXFR for the zone, but if you
           used url: to download the zonefile as a text file from a
           webserver that would work.  If you specify the hostname, you
           cannot use the domain from the zonefile, because it may not have
           that when retrieving that data, instead use a plain IP address to
           avoid a circular dependency on retrieving that IP address.

      url: <url to zonefile>
           Where to download a zonefile for the zone.  With http or https.
           An example for the url is
           "http://www.example.com/example.org.zone".  Multiple url
           statements can be given, they are tried in turn.  If only urls
           are given the SOA refresh timer is used to wait for making new
           downloads.  If also masters are listed, the masters are first
           probed with UDP SOA queries to see if the SOA serial number has
           changed, reducing the number of downloads.  If none of the urls
           work, the masters are tried with IXFR and AXFR.  For https, the
           tls-cert-bundle and the hostname from the url are used to
           authenticate the connection.  If you specify a hostname in the
           URL, you cannot use the domain from the zonefile, because it may
           not have that when retrieving that data, instead use a plain IP
           address to avoid a circular dependency on retrieving that IP
           address.  Avoid dependencies on name lookups by using a notation
           like "http://192.0.2.1/unbound-master/example.com.zone", with an
           explicit IP address.

      allow-notify: <IP address or host name
           With allow-notify you can specify additional sources of notifies.
           When notified, the server attempts to first probe and then zone
           transfer.  If the notify is from a master, it first attempts that
           master.  Otherwise other masters are attempted.  If there are no
           masters, but only urls, the file is downloaded when notified.
           The masters from master: statements are allowed notify by
           default.



                                   - 37 -           Formatted:  June 4, 2020






 unbound.conf(5)                 NLnet Labs                  unbound.conf(5)
 unbound 1.10.1                                               unbound 1.10.1

                                May 19, 2020



      fallback-enabled: <yes or no>
           Default no.  If enabled, unbound falls back to querying the
           internet as a resolver for this zone when lookups fail.  For
           example for DNSSEC validation failures.

      for-downstream: <yes or no>
           Default yes.  If enabled, unbound serves authority responses to
           downstream clients for this zone.  This option makes unbound
           behave, for the queries with names in this zone, like one of the
           authority servers for that zone.  Turn it off if you want unbound
           to provide recursion for the zone but have a local copy of zone
           data.  If for-downstream is no and for-upstream is yes, then
           unbound will DNSSEC validate the contents of the zone before
           serving the zone contents to clients and store validation results
           in the cache.

      for-upstream: <yes or no>
           Default yes.  If enabled, unbound fetches data from this data
           collection for answering recursion queries.  Instead of sending
           queries over the internet to the authority servers for this zone,
           it'll fetch the data directly from the zone data.  Turn it on
           when you want unbound to provide recursion for downstream
           clients, and use the zone data as a local copy to speed up
           lookups.

      zonefile: <filename>
           The filename where the zone is stored.  If not given then no
           zonefile is used.  If the file does not exist or is empty,
           unbound will attempt to fetch zone data (eg. from the master
           servers).

    View Options
      There may be multiple view: clauses. Each with a name: and zero or
      more local-zone and local-data elements. Views can also contain
      view-first, response-ip, response-ip-data and local-data-ptr elements.
      View can be mapped to requests by specifying the view name in an
      access-control-view element. Options from matching views will override
      global options. Global options will be used if no matching view is
      found, or when the matching view does not have the option specified.

      name: <view name>
           Name of the view. Must be unique. This name is used in
           access-control-view elements.

      local-zone: <zone> <type>
           View specific local-zone elements. Has the same types and
           behaviour as the global local-zone elements. When there is at
           least one local-zone specified and view-first is no, the default
           local-zones will be added to this view.  Defaults can be disabled



                                   - 38 -           Formatted:  June 4, 2020






 unbound.conf(5)                 NLnet Labs                  unbound.conf(5)
 unbound 1.10.1                                               unbound 1.10.1

                                May 19, 2020



           using the nodefault type. When view-first is yes or when a view
           does not have a local-zone, the global local-zone will be used
           including it's default zones.

      local-data: "<resource record string>"
           View specific local-data elements. Has the same behaviour as the
           global local-data elements.

      local-data-ptr: "IPaddr name"
           View specific local-data-ptr elements. Has the same behaviour as
           the global local-data-ptr elements.

      view-first: <yes or no>
           If enabled, it attempts to use the global local-zone and
           local-data if there is no match in the view specific options.
           The default is no.

    Python Module Options
      The python: clause gives the settings for the python(1) script module.
      This module acts like the iterator and validator modules do, on
      queries and answers.  To enable the script module it has to be
      compiled into the daemon, and the word "python" has to be put in the
      module-config: option (usually first, or between the validator and
      iterator). Multiple instances of the python module are supported by
      adding the word "python" more than once.  If the chroot: option is
      enabled, you should make sure Python's library directory structure is
      bind mounted in the new root environment, see mount(8).  Also the
      python-script: path should be specified as an absolute path relative
      to the new root, or as a relative path to the working directory.

      python-script: <python file>
           The script file to load. Repeat this option for every python
           module instance added to the module-config: option.

    DNS64 Module Options
      The dns64 module must be configured in the module-config: "dns64
      validator iterator" directive and be compiled into the daemon to be
      enabled.  These settings go in the server: section.

      dns64-prefix: <IPv6 prefix>
           This sets the DNS64 prefix to use to synthesize AAAA records
           with.  It must be /96 or shorter.  The default prefix is
           64:ff9b::/96.

      dns64-synthall: <yes or no>
           Debug option, default no.  If enabled, synthesize all AAAA
           records despite the presence of actual AAAA records.

      dns64-ignore-aaaa: <name>



                                   - 39 -           Formatted:  June 4, 2020






 unbound.conf(5)                 NLnet Labs                  unbound.conf(5)
 unbound 1.10.1                                               unbound 1.10.1

                                May 19, 2020



           List domain for which the AAAA records are ignored and the A
           record is used by dns64 processing instead.  Can be entered
           multiple times, list a new domain for which it applies, one per
           line.  Applies also to names underneath the name given.

    DNSCrypt Options
      The dnscrypt: clause gives the settings of the dnscrypt channel. While
      those options are available, they are only meaningful if unbound was
      compiled with --enable-dnscrypt.  Currently certificate and
      secret/public keys cannot be generated by unbound.  You can use
      dnscrypt-wrapper to generate those:
      https://github.com/cofyc/dnscrypt-wrapper/blob/master/README.md#usage

      dnscrypt-enable: <yes or no>
           Whether or not the dnscrypt config should be enabled. You may
           define configuration but not activate it.  The default is no.

      dnscrypt-port: <port number>
           On which port should dnscrypt should be activated. Note that you
           should have a matching interface option defined in the server
           section for this port.

      dnscrypt-provider: <provider name>
           The provider name to use to distribute certificates. This is of
           the form: 2.dnscrypt-cert.example.com.. The name MUST end with a
           dot.

      dnscrypt-secret-key: <path to secret key file>
           Path to the time limited secret key file. This option may be
           specified multiple times.

      dnscrypt-provider-cert: <path to cert file>
           Path to the certificate related to the dnscrypt-secret-keys.
           This option may be specified multiple times.

      dnscrypt-provider-cert-rotated: <path to cert file>
           Path to a certificate that we should be able to serve existing
           connection from but do not want to advertise over
           dnscrypt-provider's TXT record certs distribution.  A typical use
           case is when rotating certificates, existing clients may still
           use the client magic from the old cert in their queries until
           they fetch and update the new cert. Likewise, it would allow one
           to prime the new cert/key without distributing the new cert yet,
           this can be useful when using a network of servers using anycast
           and on which the configuration may not get updated at the exact
           same time. By priming the cert, the servers can handle both old
           and new certs traffic while distributing only one.  This option
           may be specified multiple times.




                                   - 40 -           Formatted:  June 4, 2020






 unbound.conf(5)                 NLnet Labs                  unbound.conf(5)
 unbound 1.10.1                                               unbound 1.10.1

                                May 19, 2020



      dnscrypt-shared-secret-cache-size: <memory size>
           Give the size of the data structure in which the shared secret
           keys are kept in.  Default 4m.  In bytes or use m(mega), k(kilo),
           g(giga).  The shared secret cache is used when a same client is
           making multiple queries using the same public key. It saves a
           substantial amount of CPU.

      dnscrypt-shared-secret-cache-slabs: <number>
           Give power of 2 number of slabs, this is used to reduce lock
           contention in the dnscrypt shared secrets cache.  Close to the
           number of cpus is a fairly good setting.

      dnscrypt-nonce-cache-size: <memory size>
           Give the size of the data structure in which the client nonces
           are kept in.  Default 4m. In bytes or use m(mega), k(kilo),
           g(giga).  The nonce cache is used to prevent dnscrypt message
           replaying. Client nonce should be unique for any pair of client
           pk/server sk.

      dnscrypt-nonce-cache-slabs: <number>
           Give power of 2 number of slabs, this is used to reduce lock
           contention in the dnscrypt nonce cache.  Close to the number of
           cpus is a fairly good setting.

    EDNS Client Subnet Module Options
      The ECS module must be configured in the module-config: "subnetcache
      validator iterator" directive and be compiled into the daemon to be
      enabled.  These settings go in the server: section.  If the
      destination address is whitelisted with Unbound will add the EDNS0
      option to the query containing the relevant part of the client's
      address. When an answer contains the ECS option the response and the
      option are placed in a specialized cache. If the authority indicated
      no support, the response is stored in the regular cache.
      Additionally, when a client includes the option in its queries,
      Unbound will forward the option to the authority if present in the
      whitelist, or client-subnet-always-forward is set to yes. In this case
      the lookup in the regular cache is skipped.  The maximum size of the
      ECS cache is controlled by 'msg-cache-size' in the configuration file.
      On top of that, for each query only 100 different subnets are allowed
      to be stored for each address family. Exceeding that number, older
      entries will be purged from cache.

      send-client-subnet: <IP address>
           Send client source address to this authority. Append /num to
           indicate a classless delegation netblock, for example like
           10.2.3.4/24 or 2001::11/64. Can be given multiple times.
           Authorities not listed will not receive edns-subnet information,
           unless domain in query is specified in client-subnet-zone.




                                   - 41 -           Formatted:  June 4, 2020






 unbound.conf(5)                 NLnet Labs                  unbound.conf(5)
 unbound 1.10.1                                               unbound 1.10.1

                                May 19, 2020



      client-subnet-zone: <domain>
           Send client source address in queries for this domain and its
           subdomains. Can be given multiple times. Zones not listed will
           not receive edns-subnet information, unless hosted by authority
           specified in send-client-subnet.

      client-subnet-always-forward: <yes or no>
           Specify whether the ECS whitelist check (configured using
           send-client-subnet) is applied for all queries, even if the
           triggering query contains an ECS record, or only for queries for
           which the ECS record is generated using the querier address (and
           therefore did not contain ECS data in the client query). If
           enabled, the whitelist check is skipped when the client query
           contains an ECS record. Default is no.

      max-client-subnet-ipv6: <number>
           Specifies the maximum prefix length of the client source address
           we are willing to expose to third parties for IPv6.  Defaults to
           56.

      max-client-subnet-ipv4: <number>
           Specifies the maximum prefix length of the client source address
           we are willing to expose to third parties for IPv4. Defaults to
           24.

      min-client-subnet-ipv6: <number>
           Specifies the minimum prefix length of the IPv6 source mask we
           are willing to accept in queries. Shorter source masks result in
           REFUSED answers. Source mask of 0 is always accepted. Default is
           0.

      min-client-subnet-ipv4: <number>
           Specifies the minimum prefix length of the IPv4 source mask we
           are willing to accept in queries. Shorter source masks result in
           REFUSED answers. Source mask of 0 is always accepted. Default is
           0.

      max-ecs-tree-size-ipv4: <number>
           Specifies the maximum number of subnets ECS answers kept in the
           ECS radix tree.  This number applies for each qname/qclass/qtype
           tuple. Defaults to 100.

      max-ecs-tree-size-ipv6: <number>
           Specifies the maximum number of subnets ECS answers kept in the
           ECS radix tree.  This number applies for each qname/qclass/qtype
           tuple. Defaults to 100.

    Opportunistic IPsec Support Module Options
      The IPsec module must be configured in the module-config: "ipsecmod



                                   - 42 -           Formatted:  June 4, 2020






 unbound.conf(5)                 NLnet Labs                  unbound.conf(5)
 unbound 1.10.1                                               unbound 1.10.1

                                May 19, 2020



      validator iterator" directive and be compiled into the daemon to be
      enabled.  These settings go in the server: section.  When unbound
      receives an A/AAAA query that is not in the cache and finds a valid
      answer, it will withhold returning the answer and instead will
      generate an IPSECKEY subquery for the same domain name.  If an answer
      was found, unbound will call an external hook passing the following
      arguments:

           QNAME
                Domain name of the A/AAAA and IPSECKEY query.  In string
                format.

           IPSECKEY TTL
                TTL of the IPSECKEY RRset.

           A/AAAA
                String of space separated IP addresses present in the A/AAAA
                RRset.  The IP addresses are in string format.

           IPSECKEY
                String of space separated IPSECKEY RDATA present in the
                IPSECKEY RRset.  The IPSECKEY RDATA are in DNS presentation
                format.  The A/AAAA answer is then cached and returned to
                the client.  If the external hook was called the TTL changes
                to ensure it doesn't surpass ipsecmod-max-ttl.  The same
                procedure is also followed when prefetch: is used, but the
                A/AAAA answer is given to the client before the hook is
                called.  ipsecmod-max-ttl ensures that the A/AAAA answer
                given from cache is still relevant for opportunistic IPsec.

      ipsecmod-enabled: <yes or no>
                Specifies whether the IPsec module is enabled or not.  The
                IPsec module still needs to be defined in the module-config:
                directive.  This option facilitates turning on/off the
                module without restarting/reloading unbound.  Defaults to
                yes.

      ipsecmod-hook: <filename>
                Specifies the external hook that unbound will call with
                system(3).  The file can be specified as an
                absolute/relative path.  The file needs the proper
                permissions to be able to be executed by the same user that
                runs unbound.  It must be present when the IPsec module is
                defined in the module-config: directive.

      ipsecmod-strict: <yes or no>
                If enabled unbound requires the external hook to return a
                success value of 0.  Failing to do so unbound will reply
                with SERVFAIL.  The A/AAAA answer will also not be cached.



                                   - 43 -           Formatted:  June 4, 2020






 unbound.conf(5)                 NLnet Labs                  unbound.conf(5)
 unbound 1.10.1                                               unbound 1.10.1

                                May 19, 2020



                Defaults to no.

      ipsecmod-max-ttl: <seconds>
                Time to live maximum for A/AAAA cached records after calling
                the external hook.  Defaults to 3600.

      ipsecmod-ignore-bogus: <yes or no>
                Specifies the behaviour of unbound when the IPSECKEY answer
                is bogus.  If set to yes, the hook will be called and the
                A/AAAA answer will be returned to the client.  If set to no,
                the hook will not be called and the answer to the A/AAAA
                query will be SERVFAIL.  Mainly used for testing.  Defaults
                to no.

      ipsecmod-whitelist: <domain>
                Whitelist the domain so that the module logic will be
                executed.  Can be given multiple times, for different
                domains.  If the option is not specified, all domains are
                treated as being whitelisted (default).

    Cache DB Module Options
      The Cache DB module must be configured in the module-config:
      "validator cachedb iterator" directive and be compiled into the daemon
      with --enable-cachedb.  If this module is enabled and configured, the
      specified backend database works as a second level cache: When Unbound
      cannot find an answer to a query in its built-in in-memory cache, it
      consults the specified backend.  If it finds a valid answer in the
      backend, Unbound uses it to respond to the query without performing
      iterative DNS resolution.  If Unbound cannot even find an answer in
      the backend, it resolves the query as usual, and stores the answer in
      the backend.

      This module interacts with the serve-expired-* options and will reply
      with expired data if unbound is configured for that.  Currently the
      use of serve-expired-client-timeout: and serve-expired-reply-ttl: is
      not consistent for data originating from the external cache as these
      will result in a reply with 0 TTL without trying to update the data
      first, ignoring the configured values.

      If Unbound was built with --with-libhiredis on a system that has
      installed the hiredis C client library of Redis, then the "redis"
      backend can be used.  This backend communicates with the specified
      Redis server over a TCP connection to store and retrieve cache data.
      It can be used as a persistent and/or shared cache backend.  It should
      be noted that Unbound never removes data stored in the Redis server,
      even if some data have expired in terms of DNS TTL or the Redis server
      has cached too much data; if necessary the Redis server must be
      configured to limit the cache size, preferably with some kind of
      least-recently-used eviction policy.  This backend uses synchronous



                                   - 44 -           Formatted:  June 4, 2020






 unbound.conf(5)                 NLnet Labs                  unbound.conf(5)
 unbound 1.10.1                                               unbound 1.10.1

                                May 19, 2020



      communication with the Redis server based on the assumption that the
      communication is stable and sufficiently fast.  The thread waiting for
      a response from the Redis server cannot handle other DNS queries.
      Although the backend has the ability to reconnect to the server when
      the connection is closed unexpectedly and there is a configurable
      timeout in case the server is overly slow or hangs up, these cases are
      assumed to be very rare.  If connection close or timeout happens too
      often, Unbound will be effectively unusable with this backend.  It's
      the administrator's responsibility to make the assumption hold.

      The cachedb: clause gives custom settings of the cache DB module.

      backend: <backend name>
           Specify the backend database name.  The default database is the
           in-memory backend named "testframe", which, as the name suggests,
           is not of any practical use.  Depending on the build-time
           configuration, "redis" backend may also be used as described
           above.

      secret-seed: <"secret string">
           Specify a seed to calculate a hash value from query information.
           This value will be used as the key of the corresponding answer
           for the backend database and can be customized if the hash should
           not be predictable operationally.  If the backend database is
           shared by multiple Unbound instances, all instances must use the
           same secret seed.  This option defaults to "default".

      The following cachedb otions are specific to the redis backend.

      redis-server-host: <server address or name>
           The IP (either v6 or v4) address or domain name of the Redis
           server.  In general an IP address should be specified as
           otherwise Unbound will have to resolve the name of the server
           every time it establishes a connection to the server.  This
           option defaults to "127.0.0.1".

      redis-server-port: <port number>
           The TCP port number of the Redis server.  This option defaults to
           6379.

      redis-timeout: <msec>
           The period until when Unbound waits for a response from the Redis
           sever.  If this timeout expires Unbound closes the connection,
           treats it as if the Redis server does not have the requested
           data, and will try to re-establish a new connection later.  This
           option defaults to 100 milliseconds.

    Response Policy Zone Options
      Response Policy Zones are configured with rpz:, and each one must have



                                   - 45 -           Formatted:  June 4, 2020






 unbound.conf(5)                 NLnet Labs                  unbound.conf(5)
 unbound 1.10.1                                               unbound 1.10.1

                                May 19, 2020



      a name:. There can be multiple ones, by listing multiple rpz clauses,
      each with a different name. RPZ clauses are applied in order of
      configuration. The respip module needs to be added to the module-
      config, e.g.: module-config: "respip validator iterator".

      Only the QNAME and Response IP Address triggers are supported. The
      supported RPZ actions are: NXDOMAIN, NODATA, PASSTHRU, DROP and Local
      Data. RPZ QNAME triggers are applied after local-zones and before
      auth-zones.

      name: <zone name>
           Name of the authority zone.

      master: <IP address or host name>
           Where to download a copy of the zone from, with AXFR and IXFR.
           Multiple masters can be specified.  They are all tried if one
           fails.

      url: <url to zonefile>
           Where to download a zonefile for the zone.  With http or https.
           An example for the url is
           "http://www.example.com/example.org.zone".  Multiple url
           statements can be given, they are tried in turn.  If only urls
           are given the SOA refresh timer is used to wait for making new
           downloads.  If also masters are listed, the masters are first
           probed with UDP SOA queries to see if the SOA serial number has
           changed, reducing the number of downloads.  If none of the urls
           work, the masters are tried with IXFR and AXFR.  For https, the
           tls-cert-bundle and the hostname from the url are used to
           authenticate the connection.

      allow-notify: <IP address or host name
           With allow-notify you can specify additional sources of notifies.
           When notified, the server attempts to first probe and then zone
           transfer.  If the notify is from a master, it first attempts that
           master.  Otherwise other masters are attempted.  If there are no
           masters, but only urls, the file is downloaded when notified.
           The masters from master: statements are allowed notify by
           default.

      zonefile: <filename>
           The filename where the zone is stored.  If not given then no
           zonefile is used.  If the file does not exist or is empty,
           unbound will attempt to fetch zone data (eg. from the master
           servers).

      rpz-action-override: <action>
           Always use this RPZ action for matching triggers from this zone.
           Possible action are: nxdomain, nodata, passthru, drop, disabled



                                   - 46 -           Formatted:  June 4, 2020






 unbound.conf(5)                 NLnet Labs                  unbound.conf(5)
 unbound 1.10.1                                               unbound 1.10.1

                                May 19, 2020



           and cname.

      rpz-cname-override: <domain>
           The CNAME target domain to use if the cname action is configured
           for rpz-action-override.

      rpz-log: <yes or no>
           Log all applied RPZ actions for this RPZ zone. Default is no.

      rpz-log-name: <name>
           Specify a string to be part of the log line, for easy
           referencing.

      tags: <list of tags>
           Limit the policies from this RPZ clause to clients with a
           matching tag. Tags need to be defined in define-tag and can be
           assigned to client addresses using access-control-tag. Enclose
           list of tags in quotes ("") and put spaces between tags. If no
           tags are specified the policies from this clause will be applied
           for all clients.

 MEMORY CONTROL EXAMPLE
      In the example config settings below memory usage is reduced. Some
      service levels are lower, notable very large data and a high TCP load
      are no longer supported. Very large data and high TCP loads are
      exceptional for the DNS.  DNSSEC validation is enabled, just add trust
      anchors.  If you do not have to worry about programs using more than 3
      Mb of memory, the below example is not for you. Use the defaults to
      receive full service, which on BSD-32bit tops out at 30-40 Mb after
      heavy usage.

      # example settings that reduce memory usage
      server:
           num-threads: 1
           outgoing-num-tcp: 1 # this limits TCP service, uses less buffers.
           incoming-num-tcp: 1
           outgoing-range: 60  # uses less memory, but less performance.
           msg-buffer-size: 8192   # note this limits service, 'no huge stuff'.
           msg-cache-size: 100k
           msg-cache-slabs: 1
           rrset-cache-size: 100k
           rrset-cache-slabs: 1
           infra-cache-numhosts: 200
           infra-cache-slabs: 1
           key-cache-size: 100k
           key-cache-slabs: 1
           neg-cache-size: 10k
           num-queries-per-thread: 30
           target-fetch-policy: "2 1 0 0 0 0"



                                   - 47 -           Formatted:  June 4, 2020






 unbound.conf(5)                 NLnet Labs                  unbound.conf(5)
 unbound 1.10.1                                               unbound 1.10.1

                                May 19, 2020



           harden-large-queries: "yes"
           harden-short-bufsize: "yes"

 FILES
      /usr/local/etc/unbound
           default unbound working directory.

      /usr/local/etc/unbound
           default chroot(2) location.

      /usr/local/etc/unbound/unbound.conf
           unbound configuration file.

      /usr/local/etc/unbound/unbound.pid
           default unbound pidfile with process ID of the running daemon.

      unbound.log
           unbound log file. default is to log to syslog(3).

 SEE ALSO
      unbound(8), unbound-checkconf(8).

 AUTHORS
      Unbound was written by NLnet Labs. Please see CREDITS file in the
      distribution for further details.



























                                   - 48 -           Formatted:  June 4, 2020