Skip site navigation (1)Skip section navigation (2)

FreeBSD Man Pages

Man Page or Keyword Search:
Man Architecture
Apropos Keyword Search (all sections) Output format
home | help
unbound.conf(5)                 unbound 1.4.20                 unbound.conf(5)

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/random /etc/unbound/dev/random
            # 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
       There must be whitespace between keywords. Attribute keywords end with
       a colon ':'. An attribute is followed by its containing attributes, or
       a value.

       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.  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
              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.

       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_
              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.

       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 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.

       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.

       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 1480 can fix it.  Setting to 512 bypasses even
              the 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).

       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_
              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.

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

       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). If the maximum kicks in,
              responses to clients still get decrementing TTLs based on the
              original (larger) values.  When the internal TTL expires, the
              cache item has expired.  Can be set lower to force the resolver
              to query for data often, and not trust (very large) TTL values.

       cache-min-ttl: _seconds_
              Time to live minimum for RRsets and messages in the cache.
              Default is 0.  If the 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.

       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.

       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.

       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-upstream: _yes or no_
              Enable or disable whether the upstream queries use TCP only for
              transport.  Default is no.  Useful in tunneling scenarios.

       ssl-upstream: _yes or no_
              Enabled or disable whether the upstream queries use SSL only for
              transport.  Default is no.  Useful in tunneling scenarios.  The
              SSL contains plain DNS in TCP wireformat.  The other server must
              support this (see ssl-service-key).

       ssl-service-key: _file_
              If enabled, the server provider SSL service on its TCP sockets.
              The clients have to use ssl-upstream: yes.  The file is the
              private key for the TLS session.  The public certificate is in
              the ssl-service-pem file.  Default is "", turned off.  Requires
              a restart (a reload is not enough) if changed, because the
              private key is read while root permissions are held and before
              chroot (if any).  Normal DNS TCP service is not provided and
              gives errors, this service is best run with a different port:
              config or @port suffixes in the interface config.

       ssl-service-pem: _file_
              The public key certificate pem file for the ssl service.
              Default is "", turned off.

       ssl-port: _number_
              The port number on which to provide TCP SSL service, default
              443, only interfaces configured with that port number as @number
              get the SSL service.

       do-daemonize: _yes or no_
              Enable or disable whether the unbound server forks into the
              background as a daemon. Default is yes.

       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 or allow_snoop.

              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
              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 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.

       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.

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

              If given a chroot is done to the given directory. The default is
              "/var/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
              needed.

       directory: _directory_
              Sets the working directory for the program. Default is
              "/var/unbound".

       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-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 '?'.

       pidfile: _filename_
              The process id is written to the file. Default is
              "/var/unbound/unbound.pid".  So,
              kill -HUP `cat /var/unbound/unbound.pid`
              triggers a reload,
              kill -QUIT `cat /var/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.

       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 on.

       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 on.

       harden-below-nxdomain: _yes or no_
              From draft-vixie-dnsext-resimprove, 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 (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 off.

       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 off, 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.

       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.

       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 occurence 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.

       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 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.

       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 no, because the DNS protocol RFCs mandate these
              sections, and the additional content could be of use and save
              roundtrips for clients.

       module-config: _"module names"_
              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.

       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 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.

       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.

       dlv-anchor-file: _filename_
              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-anchor: _"Resource Record"_
              Much like trust-anchor, this is a DLV anchor with the DS or
              DNSKEY inline.

       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 - 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
              protentially 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 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".

       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.

       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.

       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).

       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, 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.
                 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.

       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.

       The default zones are localhost, reverse 127.0.0.1 and ::1, 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." static
                 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."
                 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."

       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.

       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.

       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"

   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 server
       uses these clauses to setup SSLv3 / 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>
            Give IPv4 or IPv6 addresses 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.

       control-port: <port number>
            The port number to listen on for control commands, default is
            8953.  If you change this port number, and permissions have been
            dropped, a reload is not sufficient to open the port again, you
            must then restart.

       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.

       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.

       name: _domain name_
              Name of the stub zone.

       stub-host: _domain name_
              Name of stub zone nameserver. Is itself resolved before it is
              used.

       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 off.  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.

   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.  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
              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.

       forward-first: _yes or no_
              If enabled, a query is attempted without the forward 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.

   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).

       python-script: _python file_
              The script file to load.

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

FILES
       /var/unbound
              default unbound working directory.

       /var/unbound
              default chroot(2) location.

       /var/unbound/unbound.conf
              unbound configuration file.

       /var/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.

NLnet Labs                      March 21, 2013                 unbound.conf(5)

NAME | SYNOPSIS | DESCRIPTION | EXAMPLE | FILE FORMAT | MEMORY CONTROL EXAMPLE | FILES | SEE ALSO | AUTHORS

Want to link to this manual page? Use this URL:
<https://www.freebsd.org/cgi/man.cgi?query=unbound.conf&sektion=5&manpath=FreeBSD+10.0-RELEASE>

home | help