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unbound.conf(5)			 unbound 1.5.3		       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 any-
       where, 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 command-
	      line, 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  sta-
	      tistics. Default is no.

       extended-statistics: _yes or no_
	      If  enabled,  extended  statistics are printed from unbound-con-
	      trol(8).	Default	is off,	because	keeping	track of more  statis-
	      tics 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	local-
	      host.   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 spec-
	      ified the	default	port (from port) is used.

       ip-address: _ip address[@port]_
	      Same as interface: (for easy 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_
	      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	inter-
	      faces.  If  none	are  given  the	default	(all) is used. You can
	      specify the same interfaces in  interface:  and  outgoing-inter-
	      face:  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  com-
	      pile options. Larger numbers need	extra resources	from the oper-
	      ating 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 per-
	      mitted ports and subtracting the avoided ports from the  set  of
	      allowed  ports.	The  processing	starts with the	non IANA allo-
	      cated 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 fragmen-
	      tation 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).

       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.

       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 con-
	      tention 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 simultane-
	      ously.  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 (num-
	      queriesperthread / 2) / (average time  for  such	long  queries)
	      qps.   The  qps  for  short  queries  can	 be about (numqueries-
	      perthread	/ 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	 pack-
	      ets,  and	 unwanted  packets  are	 added	to the unwanted	packet
	      counter.

       so-rcvbuf: _number_
	      If not 0,	then set the SO_RCVBUF socket option to	get more  buf-
	      fer 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 buf-
	      fer 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 sys-
	      tem 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.

       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 no.  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	avail-
	      able  at compile time, if	that works it is used, if it fails, it
	      continues	silently (unless verbosity 3) without the option.

       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 kilo-
	      bytes, 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  con-
	      tains  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	infra-
	      structure	cache. Default is 50 milliseconds. Increase this value
	      if using forwarders needing more time to do recursive name reso-
	      lution.

       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.
	      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.

       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 pri-
	      vate  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, allow_snoop, deny_non_local or refuse_non_local.

	      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	opera-
	      tions 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  pol-
	      icy,  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.

       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  por-
	      tion.

	      The  pidfile can be either a relative path to the	working	direc-
	      tory, 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	daemo-
	      nized.  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 sys-
	      log(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 (signifi-
	      cantly) 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 num-
	      bers.   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 nxdo-
	      main.  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 vali-
	      dation 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 tar-
	      get-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 addi-
	      tional 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 spam-
	      blocklists 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 num-
	      ber  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  spa-
	      ces,  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 addi-
	      tion 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 ver-
	      ifying RRSIG inception and expiration dates, instead of the cur-
	      rent  date.  Do  not set this unless you are debugging signature
	      inception	and expiration.	The value -1 ignores  the  date	 alto-
	      gether, 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  (expira-
	      tion  -  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	signa-
	      tures.

       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 (expira-
	      tion - 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  sec-
	      tion  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 Dis-
	      abled) flag does not disable checking any	more.  This is	useful
	      if  legacy (w2008) servers that set the CD flag but cannot vali-
	      date DNSSEC themselves are the clients, and  then	 unbound  pro-
	      vides 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	 kilo-
	      bytes, 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: _yesno_
	      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 net-
	      work resolver for	a group	of machines, where such	lookups	should
	      be filtered (RFC compliance), this  also	stops  potential  data
	      leakage about the	local network to the upstream DNS servers.

       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, typetranspar-
	      ent, inform, 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.exam-
		 ple.com and www.foo.example.com are redirected, so that users
		 with  web  browsers  cannot  access  sites  with suffix exam-
		 ple.com.

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

	    nodefault
		 Used  to turn off default contents for	AS112 zones. The other
		 types also turn off default contents for the zone. The	'node-
		 fault'	 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 pro-
       vide  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.	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.

	    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	deter-
	    mines further processing. If local-data is configured that is  not
	    a  subdomain  of a local-zone, a transparent local-zone is config-
	    ured.  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 con-
       trol 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 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.

       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_
	    Whether  to	 require certificate authentication of control connec-
	    tions.  The	default	is "yes".  This	should not be  changed	unless
	    there  are	other  mechanisms  in place to prevent untrusted users
	    from accessing the remote control interface.

       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-con-
	    trol-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_con-
	    trol.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_con-
	    trol.pem.  This certificate	has to be signed with the server  cer-
	    tificate.	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 name-
       servers 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  authorita-
       tive  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 for-
       ward-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.

   DNS64 Module	Options
       The  dns64  module must be configured in	the module-config: "dns64 val-
       idator 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.

MEMORY CONTROL EXAMPLE
       In the example config settings below memory usage is reduced. Some ser-
       vice  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 ser-
       vice, 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  dis-
       tribution for further details.

NLnet Labs			 Mar 10, 2015		       unbound.conf(5)

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

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