1 .TH "unbound.conf" "5" "Sep 27, 2016" "NLnet Labs" "unbound 1.5.10"
3 .\" unbound.conf.5 -- unbound.conf manual
5 .\" Copyright (c) 2007, NLnet Labs. All rights reserved.
7 .\" See LICENSE for the license.
12 \- Unbound configuration file.
19 The file format has attributes and values. Some attributes have attributes inside them.
20 The notation is: attribute: value.
22 Comments start with # and last to the end of line. Empty lines are
23 ignored as is whitespace at the beginning of a line.
26 \fIunbound\-checkconf\fR(8)
27 can be used to check unbound.conf prior to usage.
29 An example config file is shown below. Copy this to /etc/unbound/unbound.conf
30 and start the server with:
33 $ unbound \-c /etc/unbound/unbound.conf
36 Most settings are the defaults. Stop the server with:
39 $ kill `cat /etc/unbound/unbound.pid`
42 Below is a minimal config file. The source distribution contains an extensive
43 example.conf file with all the options.
46 # unbound.conf(5) config file for unbound(8).
48 directory: "/etc/unbound"
50 # make sure unbound can access entropy from inside the chroot.
51 # e.g. on linux the use these commands (on BSD, devfs(8) is used):
52 # mount \-\-bind \-n /dev/random /etc/unbound/dev/random
53 # and mount \-\-bind \-n /dev/log /etc/unbound/dev/log
54 chroot: "/etc/unbound"
55 # logfile: "/etc/unbound/unbound.log" #uncomment to use logfile.
56 pidfile: "/etc/unbound/unbound.pid"
57 # verbosity: 1 # uncomment and increase to get more logging.
58 # listen on all interfaces, answer queries from the local subnet.
61 access\-control: 10.0.0.0/8 allow
62 access\-control: 2001:DB8::/64 allow
65 There must be whitespace between keywords. Attribute keywords end with a colon ':'. An attribute
66 is followed by its containing attributes, or a value.
68 Files can be included using the
70 directive. It can appear anywhere, it accepts a single file name as argument.
71 Processing continues as if the text from the included file was copied into
72 the config file at that point. If also using chroot, using full path names
73 for the included files works, relative pathnames for the included names work
74 if the directory where the daemon is started equals its chroot/working
75 directory or is specified before the include statement with directory: dir.
76 Wildcards can be used to include multiple files, see \fIglob\fR(7).
78 These options are part of the
82 .B verbosity: \fI<number>
83 The verbosity number, level 0 means no verbosity, only errors. Level 1
84 gives operational information. Level 2 gives detailed operational
85 information. Level 3 gives query level information, output per query.
86 Level 4 gives algorithm level information. Level 5 logs client
87 identification for cache misses. Default is level 1.
88 The verbosity can also be increased from the commandline, see \fIunbound\fR(8).
90 .B statistics\-interval: \fI<seconds>
91 The number of seconds between printing statistics to the log for every thread.
92 Disable with value 0 or "". Default is disabled. The histogram statistics
93 are only printed if replies were sent during the statistics interval,
94 requestlist statistics are printed for every interval (but can be 0).
95 This is because the median calculation requires data to be present.
97 .B statistics\-cumulative: \fI<yes or no>
98 If enabled, statistics are cumulative since starting unbound, without clearing
99 the statistics counters after logging the statistics. Default is no.
101 .B extended\-statistics: \fI<yes or no>
102 If enabled, extended statistics are printed from \fIunbound\-control\fR(8).
103 Default is off, because keeping track of more statistics takes time. The
104 counters are listed in \fIunbound\-control\fR(8).
106 .B num\-threads: \fI<number>
107 The number of threads to create to serve clients. Use 1 for no threading.
109 .B port: \fI<port number>
110 The port number, default 53, on which the server responds to queries.
112 .B interface: \fI<ip address[@port]>
113 Interface to use to connect to the network. This interface is listened to
114 for queries from clients, and answers to clients are given from it.
115 Can be given multiple times to work on several interfaces. If none are
116 given the default is to listen to localhost.
117 The interfaces are not changed on a reload (kill \-HUP) but only on restart.
118 A port number can be specified with @port (without spaces between
119 interface and port number), if not specified the default port (from
122 .B ip\-address: \fI<ip address[@port]>
123 Same as interface: (for easy of compatibility with nsd.conf).
125 .B interface\-automatic: \fI<yes or no>
126 Detect source interface on UDP queries and copy them to replies. This
127 feature is experimental, and needs support in your OS for particular socket
128 options. Default value is no.
130 .B outgoing\-interface: \fI<ip address or ip6 netblock>
131 Interface to use to connect to the network. This interface is used to send
132 queries to authoritative servers and receive their replies. Can be given
133 multiple times to work on several interfaces. If none are given the
134 default (all) is used. You can specify the same interfaces in
137 .B outgoing\-interface:
138 lines, the interfaces are then used for both purposes. Outgoing queries are
139 sent via a random outgoing interface to counter spoofing.
141 If an IPv6 netblock is specified instead of an individual IPv6 address,
142 outgoing UDP queries will use a randomised source address taken from the
143 netblock to counter spoofing. Requires the IPv6 netblock to be routed to the
144 host running unbound, and requires OS support for unprivileged non-local binds
145 (currently only supported on Linux). Several netblocks may be specified with
147 .B outgoing\-interface:
148 options, but do not specify both an individual IPv6 address and an IPv6
149 netblock, or the randomisation will be compromised. Consider combining with
151 to increase the likelihood of IPv6 nameservers being selected for queries.
152 On Linux you need these two commands to be able to use the freebind socket
153 option to receive traffic for the ip6 netblock:
154 ip -6 addr add mynetblock/64 dev lo &&
155 ip -6 route add local mynetblock/64 dev lo
157 .B outgoing\-range: \fI<number>
158 Number of ports to open. This number of file descriptors can be opened per
159 thread. Must be at least 1. Default depends on compile options. Larger
160 numbers need extra resources from the operating system. For performance a
161 very large value is best, use libevent to make this possible.
163 .B outgoing\-port\-permit: \fI<port number or range>
164 Permit unbound to open this port or range of ports for use to send queries.
165 A larger number of permitted outgoing ports increases resilience against
166 spoofing attempts. Make sure these ports are not needed by other daemons.
167 By default only ports above 1024 that have not been assigned by IANA are used.
168 Give a port number or a range of the form "low\-high", without spaces.
170 The \fBoutgoing\-port\-permit\fR and \fBoutgoing\-port\-avoid\fR statements
171 are processed in the line order of the config file, adding the permitted ports
172 and subtracting the avoided ports from the set of allowed ports. The
173 processing starts with the non IANA allocated ports above 1024 in the set
176 .B outgoing\-port\-avoid: \fI<port number or range>
177 Do not permit unbound to open this port or range of ports for use to send
178 queries. Use this to make sure unbound does not grab a port that another
179 daemon needs. The port is avoided on all outgoing interfaces, both IP4 and IP6.
180 By default only ports above 1024 that have not been assigned by IANA are used.
181 Give a port number or a range of the form "low\-high", without spaces.
183 .B outgoing\-num\-tcp: \fI<number>
184 Number of outgoing TCP buffers to allocate per thread. Default is 10. If
185 set to 0, or if do\-tcp is "no", no TCP queries to authoritative servers
186 are done. For larger installations increasing this value is a good idea.
188 .B incoming\-num\-tcp: \fI<number>
189 Number of incoming TCP buffers to allocate per thread. Default is
190 10. If set to 0, or if do\-tcp is "no", no TCP queries from clients are
191 accepted. For larger installations increasing this value is a good idea.
193 .B edns\-buffer\-size: \fI<number>
194 Number of bytes size to advertise as the EDNS reassembly buffer size.
195 This is the value put into datagrams over UDP towards peers. The actual
196 buffer size is determined by msg\-buffer\-size (both for TCP and UDP). Do
197 not set higher than that value. Default is 4096 which is RFC recommended.
198 If you have fragmentation reassembly problems, usually seen as timeouts,
199 then a value of 1480 can fix it. Setting to 512 bypasses even the most
200 stringent path MTU problems, but is seen as extreme, since the amount
201 of TCP fallback generated is excessive (probably also for this resolver,
202 consider tuning the outgoing tcp number).
204 .B max\-udp\-size: \fI<number>
205 Maximum UDP response size (not applied to TCP response). 65536 disables the
206 udp response size maximum, and uses the choice from the client, always.
207 Suggested values are 512 to 4096. Default is 4096.
209 .B msg\-buffer\-size: \fI<number>
210 Number of bytes size of the message buffers. Default is 65552 bytes, enough
211 for 64 Kb packets, the maximum DNS message size. No message larger than this
212 can be sent or received. Can be reduced to use less memory, but some requests
213 for DNS data, such as for huge resource records, will result in a SERVFAIL
216 .B msg\-cache\-size: \fI<number>
217 Number of bytes size of the message cache. Default is 4 megabytes.
218 A plain number is in bytes, append 'k', 'm' or 'g' for kilobytes, megabytes
219 or gigabytes (1024*1024 bytes in a megabyte).
221 .B msg\-cache\-slabs: \fI<number>
222 Number of slabs in the message cache. Slabs reduce lock contention by threads.
223 Must be set to a power of 2. Setting (close) to the number of cpus is a
226 .B num\-queries\-per\-thread: \fI<number>
227 The number of queries that every thread will service simultaneously.
228 If more queries arrive that need servicing, and no queries can be jostled out
229 (see \fIjostle\-timeout\fR), then the queries are dropped. This forces
230 the client to resend after a timeout; allowing the server time to work on
231 the existing queries. Default depends on compile options, 512 or 1024.
233 .B jostle\-timeout: \fI<msec>
234 Timeout used when the server is very busy. Set to a value that usually
235 results in one roundtrip to the authority servers. If too many queries
236 arrive, then 50% of the queries are allowed to run to completion, and
237 the other 50% are replaced with the new incoming query if they have already
238 spent more than their allowed time. This protects against denial of
239 service by slow queries or high query rates. Default 200 milliseconds.
240 The effect is that the qps for long-lasting queries is about
241 (numqueriesperthread / 2) / (average time for such long queries) qps.
242 The qps for short queries can be about (numqueriesperthread / 2)
243 / (jostletimeout in whole seconds) qps per thread, about (1024/2)*5 = 2560
246 .B delay\-close: \fI<msec>
247 Extra delay for timeouted UDP ports before they are closed, in msec.
248 Default is 0, and that disables it. This prevents very delayed answer
249 packets from the upstream (recursive) servers from bouncing against
250 closed ports and setting off all sort of close-port counters, with
251 eg. 1500 msec. When timeouts happen you need extra sockets, it checks
252 the ID and remote IP of packets, and unwanted packets are added to the
253 unwanted packet counter.
255 .B so\-rcvbuf: \fI<number>
256 If not 0, then set the SO_RCVBUF socket option to get more buffer
257 space on UDP port 53 incoming queries. So that short spikes on busy
258 servers do not drop packets (see counter in netstat \-su). Default is
259 0 (use system value). Otherwise, the number of bytes to ask for, try
260 "4m" on a busy server. The OS caps it at a maximum, on linux unbound
261 needs root permission to bypass the limit, or the admin can use sysctl
262 net.core.rmem_max. On BSD change kern.ipc.maxsockbuf in /etc/sysctl.conf.
263 On OpenBSD change header and recompile kernel. On Solaris ndd \-set
264 /dev/udp udp_max_buf 8388608.
266 .B so\-sndbuf: \fI<number>
267 If not 0, then set the SO_SNDBUF socket option to get more buffer space on
268 UDP port 53 outgoing queries. This for very busy servers handles spikes
269 in answer traffic, otherwise 'send: resource temporarily unavailable'
270 can get logged, the buffer overrun is also visible by netstat \-su.
271 Default is 0 (use system value). Specify the number of bytes to ask
272 for, try "4m" on a very busy server. The OS caps it at a maximum, on
273 linux unbound needs root permission to bypass the limit, or the admin
274 can use sysctl net.core.wmem_max. On BSD, Solaris changes are similar
277 .B so\-reuseport: \fI<yes or no>
278 If yes, then open dedicated listening sockets for incoming queries for each
279 thread and try to set the SO_REUSEPORT socket option on each socket. May
280 distribute incoming queries to threads more evenly. Default is no. On Linux
281 it is supported in kernels >= 3.9. On other systems, FreeBSD, OSX it may
282 also work. You can enable it (on any platform and kernel),
283 it then attempts to open the port and passes the option if it was available
284 at compile time, if that works it is used, if it fails, it continues
285 silently (unless verbosity 3) without the option.
287 .B ip\-transparent: \fI<yes or no>
288 If yes, then use IP_TRANSPARENT socket option on sockets where unbound
289 is listening for incoming traffic. Default no. Allows you to bind to
290 non\-local interfaces. For example for non\-existant IP addresses that
291 are going to exist later on, with host failover configuration. This is
292 a lot like interface\-automatic, but that one services all interfaces
293 and with this option you can select which (future) interfaces unbound
294 provides service on. This option needs unbound to be started with root
295 permissions on some systems. The option uses IP_BINDANY on FreeBSD systems.
297 .B ip\-freebind: \fI<yes or no>
298 If yes, then use IP_FREEBIND socket option on sockets where unbound
299 is listening to incoming traffic. Default no. Allows you to bind to
300 IP addresses that are nonlocal or do not exist, like when the network
301 interface or IP address is down. Exists only on Linux, where the similar
302 ip\-transparent option is also available.
304 .B rrset\-cache\-size: \fI<number>
305 Number of bytes size of the RRset cache. Default is 4 megabytes.
306 A plain number is in bytes, append 'k', 'm' or 'g' for kilobytes, megabytes
307 or gigabytes (1024*1024 bytes in a megabyte).
309 .B rrset\-cache\-slabs: \fI<number>
310 Number of slabs in the RRset cache. Slabs reduce lock contention by threads.
311 Must be set to a power of 2.
313 .B cache\-max\-ttl: \fI<seconds>
314 Time to live maximum for RRsets and messages in the cache. Default is
315 86400 seconds (1 day). If the maximum kicks in, responses to clients
316 still get decrementing TTLs based on the original (larger) values.
317 When the internal TTL expires, the cache item has expired.
318 Can be set lower to force the resolver to query for data often, and not
319 trust (very large) TTL values.
321 .B cache\-min\-ttl: \fI<seconds>
322 Time to live minimum for RRsets and messages in the cache. Default is 0.
323 If the minimum kicks in, the data is cached for longer than the domain
324 owner intended, and thus less queries are made to look up the data.
325 Zero makes sure the data in the cache is as the domain owner intended,
326 higher values, especially more than an hour or so, can lead to trouble as
327 the data in the cache does not match up with the actual data any more.
329 .B cache\-max\-negative\-ttl: \fI<seconds>
330 Time to live maximum for negative responses, these have a SOA in the
331 authority section that is limited in time. Default is 3600.
333 .B infra\-host\-ttl: \fI<seconds>
334 Time to live for entries in the host cache. The host cache contains
335 roundtrip timing, lameness and EDNS support information. Default is 900.
337 .B infra\-cache\-slabs: \fI<number>
338 Number of slabs in the infrastructure cache. Slabs reduce lock contention
339 by threads. Must be set to a power of 2.
341 .B infra\-cache\-numhosts: \fI<number>
342 Number of hosts for which information is cached. Default is 10000.
344 .B infra\-cache\-min\-rtt: \fI<msec>
345 Lower limit for dynamic retransmit timeout calculation in infrastructure
346 cache. Default is 50 milliseconds. Increase this value if using forwarders
347 needing more time to do recursive name resolution.
349 .B define\-tag: \fI<"list of tags">
350 Define the tags that can be used with local\-zone and access\-control.
351 Enclose the list between quotes ("") and put spaces between tags.
353 .B do\-ip4: \fI<yes or no>
354 Enable or disable whether ip4 queries are answered or issued. Default is yes.
356 .B do\-ip6: \fI<yes or no>
357 Enable or disable whether ip6 queries are answered or issued. Default is yes.
358 If disabled, queries are not answered on IPv6, and queries are not sent on
359 IPv6 to the internet nameservers. With this option you can disable the
360 ipv6 transport for sending DNS traffic, it does not impact the contents of
361 the DNS traffic, which may have ip4 and ip6 addresses in it.
363 .B prefer\-ip6: \fI<yes or no>
364 If enabled, prefer IPv6 transport for sending DNS queries to internet
365 nameservers. Default is no.
367 .B do\-udp: \fI<yes or no>
368 Enable or disable whether UDP queries are answered or issued. Default is yes.
370 .B do\-tcp: \fI<yes or no>
371 Enable or disable whether TCP queries are answered or issued. Default is yes.
373 .B tcp\-mss: \fI<number>
374 Maximum segment size (MSS) of TCP socket on which the server responds
375 to queries. Value lower than common MSS on Ethernet
376 (1220 for example) will address path MTU problem.
377 Note that not all platform supports socket option to set MSS (TCP_MAXSEG).
378 Default is system default MSS determined by interface MTU and
379 negotiation between server and client.
381 .B outgoing\-tcp\-mss: \fI<number>
382 Maximum segment size (MSS) of TCP socket for outgoing queries
383 (from Unbound to other servers). Value lower than
384 common MSS on Ethernet (1220 for example) will address path MTU problem.
385 Note that not all platform supports socket option to set MSS (TCP_MAXSEG).
386 Default is system default MSS determined by interface MTU and
387 negotiation between Unbound and other servers.
389 .B tcp\-upstream: \fI<yes or no>
390 Enable or disable whether the upstream queries use TCP only for transport.
391 Default is no. Useful in tunneling scenarios.
393 .B ssl\-upstream: \fI<yes or no>
394 Enabled or disable whether the upstream queries use SSL only for transport.
395 Default is no. Useful in tunneling scenarios. The SSL contains plain DNS in
396 TCP wireformat. The other server must support this (see \fBssl\-service\-key\fR).
398 .B ssl\-service-key: \fI<file>
399 If enabled, the server provider SSL service on its TCP sockets. The clients
400 have to use ssl\-upstream: yes. The file is the private key for the TLS
401 session. The public certificate is in the ssl\-service\-pem file. Default
402 is "", turned off. Requires a restart (a reload is not enough) if changed,
403 because the private key is read while root permissions are held and before
404 chroot (if any). Normal DNS TCP service is not provided and gives errors,
405 this service is best run with a different \fBport:\fR config or \fI@port\fR
406 suffixes in the \fBinterface\fR config.
408 .B ssl\-service\-pem: \fI<file>
409 The public key certificate pem file for the ssl service. Default is "",
412 .B ssl\-port: \fI<number>
413 The port number on which to provide TCP SSL service, default 853, only
414 interfaces configured with that port number as @number get the SSL service.
416 .B do\-daemonize: \fI<yes or no>
417 Enable or disable whether the unbound server forks into the background as
418 a daemon. Default is yes.
420 .B access\-control: \fI<IP netblock> <action>
421 The netblock is given as an IP4 or IP6 address with /size appended for a
422 classless network block. The action can be \fIdeny\fR, \fIrefuse\fR,
423 \fIallow\fR, \fIallow_snoop\fR, \fIdeny_non_local\fR or \fIrefuse_non_local\fR.
424 The most specific netblock match is used, if none match \fIdeny\fR is used.
426 The action \fIdeny\fR stops queries from hosts from that netblock.
428 The action \fIrefuse\fR stops queries too, but sends a DNS rcode REFUSED
431 The action \fIallow\fR gives access to clients from that netblock.
432 It gives only access for recursion clients (which is
433 what almost all clients need). Nonrecursive queries are refused.
435 The \fIallow\fR action does allow nonrecursive queries to access the
436 local\-data that is configured. The reason is that this does not involve
437 the unbound server recursive lookup algorithm, and static data is served
438 in the reply. This supports normal operations where nonrecursive queries
439 are made for the authoritative data. For nonrecursive queries any replies
440 from the dynamic cache are refused.
442 The action \fIallow_snoop\fR gives nonrecursive access too. This give
443 both recursive and non recursive access. The name \fIallow_snoop\fR refers
444 to cache snooping, a technique to use nonrecursive queries to examine
445 the cache contents (for malicious acts). However, nonrecursive queries can
446 also be a valuable debugging tool (when you want to examine the cache
447 contents). In that case use \fIallow_snoop\fR for your administration host.
449 By default only localhost is \fIallow\fRed, the rest is \fIrefuse\fRd.
450 The default is \fIrefuse\fRd, because that is protocol\-friendly. The DNS
451 protocol is not designed to handle dropped packets due to policy, and
452 dropping may result in (possibly excessive) retried queries.
454 The deny_non_local and refuse_non_local settings are for hosts that are
455 only allowed to query for the authoritative local\-data, they are not
456 allowed full recursion but only the static data. With deny_non_local,
457 messages that are disallowed are dropped, with refuse_non_local they
458 receive error code REFUSED.
460 .B access\-control\-tag: \fI<IP netblock> <"list of tags">
461 Assign tags to access-control elements. Clients using this access control
462 element use localzones that are tagged with one of these tags. Tags must be
463 defined in \fIdefine\-tags\fR. Enclose list of tags in quotes ("") and put
464 spaces between tags. If access\-control\-tag is configured for a netblock that
465 does not have an access\-control, an access\-control element with action
466 \fIallow\fR is configured for this netblock.
468 .B access\-control\-tag\-action: \fI<IP netblock> <tag> <action>
469 Set action for particular tag for given access control element. If you have
470 multiple tag values, the tag used to lookup the action is the first tag match
471 between access\-control\-tag and local\-zone\-tag where "first" comes from the
472 order of the define-tag values.
474 .B access\-control\-tag\-data: \fI<IP netblock> <tag> <"resource record string">
475 Set redirect data for particular tag for given access control element.
477 .B chroot: \fI<directory>
478 If chroot is enabled, you should pass the configfile (from the
479 commandline) as a full path from the original root. After the
480 chroot has been performed the now defunct portion of the config
481 file path is removed to be able to reread the config after a reload.
483 All other file paths (working dir, logfile, roothints, and
484 key files) can be specified in several ways:
485 as an absolute path relative to the new root,
486 as a relative path to the working directory, or
487 as an absolute path relative to the original root.
488 In the last case the path is adjusted to remove the unused portion.
490 The pidfile can be either a relative path to the working directory, or
491 an absolute path relative to the original root. It is written just prior
492 to chroot and dropping permissions. This allows the pidfile to be
493 /var/run/unbound.pid and the chroot to be /var/unbound, for example.
495 Additionally, unbound may need to access /dev/random (for entropy)
496 from inside the chroot.
498 If given a chroot is done to the given directory. The default is
499 "/var/unbound". If you give "" no chroot is performed.
501 .B username: \fI<name>
502 If given, after binding the port the user privileges are dropped. Default is
503 "unbound". If you give username: "" no user change is performed.
505 If this user is not capable of binding the
506 port, reloads (by signal HUP) will still retain the opened ports.
507 If you change the port number in the config file, and that new port number
508 requires privileges, then a reload will fail; a restart is needed.
510 .B directory: \fI<directory>
511 Sets the working directory for the program. Default is "/var/unbound".
512 On Windows the string "%EXECUTABLE%" tries to change to the directory
513 that unbound.exe resides in.
514 If you give a server: directory: dir before include: file statements
515 then those includes can be relative to the working directory.
517 .B logfile: \fI<filename>
518 If "" is given, logging goes to stderr, or nowhere once daemonized.
519 The logfile is appended to, in the following format:
521 [seconds since 1970] unbound[pid:tid]: type: message.
523 If this option is given, the use\-syslog is option is set to "no".
524 The logfile is reopened (for append) when the config file is reread, on
527 .B use\-syslog: \fI<yes or no>
528 Sets unbound to send log messages to the syslogd, using
530 The log facility LOG_DAEMON is used, with identity "unbound".
531 The logfile setting is overridden when use\-syslog is turned on.
532 The default is to log to syslog.
534 .B log\-time\-ascii: \fI<yes or no>
535 Sets logfile lines to use a timestamp in UTC ascii. Default is no, which
536 prints the seconds since 1970 in brackets. No effect if using syslog, in
537 that case syslog formats the timestamp printed into the log files.
539 .B log\-queries: \fI<yes or no>
540 Prints one line per query to the log, with the log timestamp and IP address,
541 name, type and class. Default is no. Note that it takes time to print these
542 lines which makes the server (significantly) slower. Odd (nonprintable)
543 characters in names are printed as '?'.
545 .B pidfile: \fI<filename>
546 The process id is written to the file. Default is "/var/unbound/unbound.pid".
549 kill \-HUP `cat /var/unbound/unbound.pid`
553 kill \-TERM `cat /var/unbound/unbound.pid`
555 gracefully terminates.
557 .B root\-hints: \fI<filename>
558 Read the root hints from this file. Default is nothing, using builtin hints
559 for the IN class. The file has the format of zone files, with root
560 nameserver names and addresses only. The default may become outdated,
561 when servers change, therefore it is good practice to use a root\-hints file.
563 .B hide\-identity: \fI<yes or no>
564 If enabled id.server and hostname.bind queries are refused.
566 .B identity: \fI<string>
567 Set the identity to report. If set to "", the default, then the hostname
568 of the server is returned.
570 .B hide\-version: \fI<yes or no>
571 If enabled version.server and version.bind queries are refused.
573 .B version: \fI<string>
574 Set the version to report. If set to "", the default, then the package
577 .B target\-fetch\-policy: \fI<"list of numbers">
578 Set the target fetch policy used by unbound to determine if it should fetch
579 nameserver target addresses opportunistically. The policy is described per
582 The number of values determines the maximum dependency depth
583 that unbound will pursue in answering a query.
584 A value of \-1 means to fetch all targets opportunistically for that dependency
585 depth. A value of 0 means to fetch on demand only. A positive value fetches
586 that many targets opportunistically.
588 Enclose the list between quotes ("") and put spaces between numbers.
589 The default is "3 2 1 0 0". Setting all zeroes, "0 0 0 0 0" gives behaviour
590 closer to that of BIND 9, while setting "\-1 \-1 \-1 \-1 \-1" gives behaviour
591 rumoured to be closer to that of BIND 8.
593 .B harden\-short\-bufsize: \fI<yes or no>
594 Very small EDNS buffer sizes from queries are ignored. Default is off, since
595 it is legal protocol wise to send these, and unbound tries to give very
596 small answers to these queries, where possible.
598 .B harden\-large\-queries: \fI<yes or no>
599 Very large queries are ignored. Default is off, since it is legal protocol
600 wise to send these, and could be necessary for operation if TSIG or EDNS
601 payload is very large.
603 .B harden\-glue: \fI<yes or no>
604 Will trust glue only if it is within the servers authority. Default is on.
606 .B harden\-dnssec\-stripped: \fI<yes or no>
607 Require DNSSEC data for trust\-anchored zones, if such data is absent,
608 the zone becomes bogus. If turned off, and no DNSSEC data is received
609 (or the DNSKEY data fails to validate), then the zone is made insecure,
610 this behaves like there is no trust anchor. You could turn this off if
611 you are sometimes behind an intrusive firewall (of some sort) that
612 removes DNSSEC data from packets, or a zone changes from signed to
613 unsigned to badly signed often. If turned off you run the risk of a
614 downgrade attack that disables security for a zone. Default is on.
616 .B harden\-below\-nxdomain: \fI<yes or no>
617 From draft\-vixie\-dnsext\-resimprove, returns nxdomain to queries for a name
618 below another name that is already known to be nxdomain. DNSSEC mandates
619 noerror for empty nonterminals, hence this is possible. Very old software
620 might return nxdomain for empty nonterminals (that usually happen for reverse
621 IP address lookups), and thus may be incompatible with this. To try to avoid
622 this only DNSSEC-secure nxdomains are used, because the old software does not
623 have DNSSEC. Default is off.
624 Currently, draft\-ietf\-dnsop\-nxdomain\-cut promotes this technique.
626 .B harden\-referral\-path: \fI<yes or no>
627 Harden the referral path by performing additional queries for
628 infrastructure data. Validates the replies if trust anchors are configured
629 and the zones are signed. This enforces DNSSEC validation on nameserver
630 NS sets and the nameserver addresses that are encountered on the referral
632 Default off, because it burdens the authority servers, and it is
633 not RFC standard, and could lead to performance problems because of the
634 extra query load that is generated. Experimental option.
635 If you enable it consider adding more numbers after the target\-fetch\-policy
636 to increase the max depth that is checked to.
638 .B harden\-algo\-downgrade: \fI<yes or no>
639 Harden against algorithm downgrade when multiple algorithms are
640 advertised in the DS record. If no, allows the weakest algorithm to
641 validate the zone. Default is no. Zone signers must produce zones
642 that allow this feature to work, but sometimes they do not, and turning
643 this option off avoids that validation failure.
645 .B use\-caps\-for\-id: \fI<yes or no>
646 Use 0x20\-encoded random bits in the query to foil spoof attempts.
647 This perturbs the lowercase and uppercase of query names sent to
648 authority servers and checks if the reply still has the correct casing.
650 This feature is an experimental implementation of draft dns\-0x20.
652 .B caps\-whitelist: \fI<domain>
653 Whitelist the domain so that it does not receive caps\-for\-id perturbed
654 queries. For domains that do not support 0x20 and also fail with fallback
655 because they keep sending different answers, like some load balancers.
656 Can be given multiple times, for different domains.
658 .B qname\-minimisation: \fI<yes or no>
659 Send minimum amount of information to upstream servers to enhance privacy.
660 Only sent minimum required labels of the QNAME and set QTYPE to NS when
661 possible. Best effort approach, full QNAME and original QTYPE will be sent when
662 upstream replies with a RCODE other than NOERROR. Default is off.
664 .B private\-address: \fI<IP address or subnet>
665 Give IPv4 of IPv6 addresses or classless subnets. These are addresses
666 on your private network, and are not allowed to be returned for
667 public internet names. Any occurrence of such addresses are removed
668 from DNS answers. Additionally, the DNSSEC validator may mark the
669 answers bogus. This protects against so\-called DNS Rebinding, where
670 a user browser is turned into a network proxy, allowing remote access
671 through the browser to other parts of your private network. Some names
672 can be allowed to contain your private addresses, by default all the
673 \fBlocal\-data\fR that you configured is allowed to, and you can specify
674 additional names using \fBprivate\-domain\fR. No private addresses are
675 enabled by default. We consider to enable this for the RFC1918 private
676 IP address space by default in later releases. That would enable private
677 addresses for 10.0.0.0/8 172.16.0.0/12 192.168.0.0/16 169.254.0.0/16
678 fd00::/8 and fe80::/10, since the RFC standards say these addresses
679 should not be visible on the public internet. Turning on 127.0.0.0/8
680 would hinder many spamblocklists as they use that. Adding ::ffff:0:0/96
681 stops IPv4-mapped IPv6 addresses from bypassing the filter.
683 .B private\-domain: \fI<domain name>
684 Allow this domain, and all its subdomains to contain private addresses.
685 Give multiple times to allow multiple domain names to contain private
686 addresses. Default is none.
688 .B unwanted\-reply\-threshold: \fI<number>
689 If set, a total number of unwanted replies is kept track of in every thread.
690 When it reaches the threshold, a defensive action is taken and a warning
691 is printed to the log. The defensive action is to clear the rrset and
692 message caches, hopefully flushing away any poison. A value of 10 million
693 is suggested. Default is 0 (turned off).
695 .B do\-not\-query\-address: \fI<IP address>
696 Do not query the given IP address. Can be IP4 or IP6. Append /num to
697 indicate a classless delegation netblock, for example like
698 10.2.3.4/24 or 2001::11/64.
700 .B do\-not\-query\-localhost: \fI<yes or no>
701 If yes, localhost is added to the do\-not\-query\-address entries, both
702 IP6 ::1 and IP4 127.0.0.1/8. If no, then localhost can be used to send
703 queries to. Default is yes.
705 .B prefetch: \fI<yes or no>
706 If yes, message cache elements are prefetched before they expire to
707 keep the cache up to date. Default is no. Turning it on gives about
708 10 percent more traffic and load on the machine, but popular items do
709 not expire from the cache.
711 .B prefetch-key: \fI<yes or no>
712 If yes, fetch the DNSKEYs earlier in the validation process, when a DS
713 record is encountered. This lowers the latency of requests. It does use
714 a little more CPU. Also if the cache is set to 0, it is no use. Default is no.
716 .B rrset-roundrobin: \fI<yes or no>
717 If yes, Unbound rotates RRSet order in response (the random number is taken
718 from the query ID, for speed and thread safety). Default is no.
720 .B minimal-responses: \fI<yes or no>
721 If yes, Unbound doesn't insert authority/additional sections into response
722 messages when those sections are not required. This reduces response
723 size significantly, and may avoid TCP fallback for some responses.
724 This may cause a slight speedup. The default is no, because the DNS
725 protocol RFCs mandate these sections, and the additional content could
726 be of use and save roundtrips for clients.
728 .B disable-dnssec-lame-check: \fI<yes or no>
729 If true, disables the DNSSEC lameness check in the iterator. This check
730 sees if RRSIGs are present in the answer, when dnssec is expected,
731 and retries another authority if RRSIGs are unexpectedly missing.
732 The validator will insist in RRSIGs for DNSSEC signed domains regardless
733 of this setting, if a trust anchor is loaded.
735 .B module\-config: \fI<"module names">
736 Module configuration, a list of module names separated by spaces, surround
737 the string with quotes (""). The modules can be validator, iterator.
738 Setting this to "iterator" will result in a non\-validating server.
739 Setting this to "validator iterator" will turn on DNSSEC validation.
740 The ordering of the modules is important.
741 You must also set trust\-anchors for validation to be useful.
743 .B trust\-anchor\-file: \fI<filename>
744 File with trusted keys for validation. Both DS and DNSKEY entries can appear
745 in the file. The format of the file is the standard DNS Zone file format.
746 Default is "", or no trust anchor file.
748 .B auto\-trust\-anchor\-file: \fI<filename>
749 File with trust anchor for one zone, which is tracked with RFC5011 probes.
750 The probes are several times per month, thus the machine must be online
751 frequently. The initial file can be one with contents as described in
752 \fBtrust\-anchor\-file\fR. The file is written to when the anchor is updated,
753 so the unbound user must have write permission. Write permission to the file,
754 but also to the directory it is in (to create a temporary file, which is
755 necessary to deal with filesystem full events).
757 .B trust\-anchor: \fI<"Resource Record">
758 A DS or DNSKEY RR for a key to use for validation. Multiple entries can be
759 given to specify multiple trusted keys, in addition to the trust\-anchor\-files.
760 The resource record is entered in the same format as 'dig' or 'drill' prints
761 them, the same format as in the zone file. Has to be on a single line, with
762 "" around it. A TTL can be specified for ease of cut and paste, but is ignored.
763 A class can be specified, but class IN is default.
765 .B trusted\-keys\-file: \fI<filename>
766 File with trusted keys for validation. Specify more than one file
767 with several entries, one file per entry. Like \fBtrust\-anchor\-file\fR
768 but has a different file format. Format is BIND\-9 style format,
769 the trusted\-keys { name flag proto algo "key"; }; clauses are read.
770 It is possible to use wildcards with this statement, the wildcard is
771 expanded on start and on reload.
773 .B dlv\-anchor\-file: \fI<filename>
774 This option was used during early days DNSSEC deployment when no parent-side
775 DS record registrations were easily available. Nowadays, it is best to have
776 DS records registered with the parent zone (many top level zones are signed).
777 File with trusted keys for DLV (DNSSEC Lookaside Validation). Both DS and
778 DNSKEY entries can be used in the file, in the same format as for
779 \fItrust\-anchor\-file:\fR statements. Only one DLV can be configured, more
780 would be slow. The DLV configured is used as a root trusted DLV, this
781 means that it is a lookaside for the root. Default is "", or no dlv anchor file.
782 DLV is going to be decommissioned. Please do not use it any more.
784 .B dlv\-anchor: \fI<"Resource Record">
785 Much like trust\-anchor, this is a DLV anchor with the DS or DNSKEY inline.
786 DLV is going to be decommissioned. Please do not use it any more.
788 .B domain\-insecure: \fI<domain name>
789 Sets domain name to be insecure, DNSSEC chain of trust is ignored towards
790 the domain name. So a trust anchor above the domain name can not make the
791 domain secure with a DS record, such a DS record is then ignored.
792 Also keys from DLV are ignored for the domain. Can be given multiple times
793 to specify multiple domains that are treated as if unsigned. If you set
794 trust anchors for the domain they override this setting (and the domain
797 This can be useful if you want to make sure a trust anchor for external
798 lookups does not affect an (unsigned) internal domain. A DS record
799 externally can create validation failures for that internal domain.
801 .B val\-override\-date: \fI<rrsig\-style date spec>
802 Default is "" or "0", which disables this debugging feature. If enabled by
803 giving a RRSIG style date, that date is used for verifying RRSIG inception
804 and expiration dates, instead of the current date. Do not set this unless
805 you are debugging signature inception and expiration. The value \-1 ignores
806 the date altogether, useful for some special applications.
808 .B val\-sig\-skew\-min: \fI<seconds>
809 Minimum number of seconds of clock skew to apply to validated signatures.
810 A value of 10% of the signature lifetime (expiration \- inception) is
811 used, capped by this setting. Default is 3600 (1 hour) which allows for
812 daylight savings differences. Lower this value for more strict checking
813 of short lived signatures.
815 .B val\-sig\-skew\-max: \fI<seconds>
816 Maximum number of seconds of clock skew to apply to validated signatures.
817 A value of 10% of the signature lifetime (expiration \- inception)
818 is used, capped by this setting. Default is 86400 (24 hours) which
819 allows for timezone setting problems in stable domains. Setting both
820 min and max very low disables the clock skew allowances. Setting both
821 min and max very high makes the validator check the signature timestamps
824 .B val\-bogus\-ttl: \fI<number>
825 The time to live for bogus data. This is data that has failed validation;
826 due to invalid signatures or other checks. The TTL from that data cannot be
827 trusted, and this value is used instead. The value is in seconds, default 60.
828 The time interval prevents repeated revalidation of bogus data.
830 .B val\-clean\-additional: \fI<yes or no>
831 Instruct the validator to remove data from the additional section of secure
832 messages that are not signed properly. Messages that are insecure, bogus,
833 indeterminate or unchecked are not affected. Default is yes. Use this setting
834 to protect the users that rely on this validator for authentication from
835 potentially bad data in the additional section.
837 .B val\-log\-level: \fI<number>
838 Have the validator print validation failures to the log. Regardless of
839 the verbosity setting. Default is 0, off. At 1, for every user query
840 that fails a line is printed to the logs. This way you can monitor what
841 happens with validation. Use a diagnosis tool, such as dig or drill,
842 to find out why validation is failing for these queries. At 2, not only
843 the query that failed is printed but also the reason why unbound thought
844 it was wrong and which server sent the faulty data.
846 .B val\-permissive\-mode: \fI<yes or no>
847 Instruct the validator to mark bogus messages as indeterminate. The security
848 checks are performed, but if the result is bogus (failed security), the
849 reply is not withheld from the client with SERVFAIL as usual. The client
850 receives the bogus data. For messages that are found to be secure the AD bit
851 is set in replies. Also logging is performed as for full validation.
852 The default value is "no".
854 .B ignore\-cd\-flag: \fI<yes or no>
855 Instruct unbound to ignore the CD flag from clients and refuse to
856 return bogus answers to them. Thus, the CD (Checking Disabled) flag
857 does not disable checking any more. This is useful if legacy (w2008)
858 servers that set the CD flag but cannot validate DNSSEC themselves are
859 the clients, and then unbound provides them with DNSSEC protection.
860 The default value is "no".
862 .B val\-nsec3\-keysize\-iterations: \fI<"list of values">
863 List of keysize and iteration count values, separated by spaces, surrounded
864 by quotes. Default is "1024 150 2048 500 4096 2500". This determines the
865 maximum allowed NSEC3 iteration count before a message is simply marked
866 insecure instead of performing the many hashing iterations. The list must
867 be in ascending order and have at least one entry. If you set it to
868 "1024 65535" there is no restriction to NSEC3 iteration values.
869 This table must be kept short; a very long list could cause slower operation.
871 .B add\-holddown: \fI<seconds>
872 Instruct the \fBauto\-trust\-anchor\-file\fR probe mechanism for RFC5011
873 autotrust updates to add new trust anchors only after they have been
874 visible for this time. Default is 30 days as per the RFC.
876 .B del\-holddown: \fI<seconds>
877 Instruct the \fBauto\-trust\-anchor\-file\fR probe mechanism for RFC5011
878 autotrust updates to remove revoked trust anchors after they have been
879 kept in the revoked list for this long. Default is 30 days as per
882 .B keep\-missing: \fI<seconds>
883 Instruct the \fBauto\-trust\-anchor\-file\fR probe mechanism for RFC5011
884 autotrust updates to remove missing trust anchors after they have been
885 unseen for this long. This cleans up the state file if the target zone
886 does not perform trust anchor revocation, so this makes the auto probe
887 mechanism work with zones that perform regular (non\-5011) rollovers.
888 The default is 366 days. The value 0 does not remove missing anchors,
891 .B permit\-small\-holddown: \fI<yes or no>
892 Debug option that allows the autotrust 5011 rollover timers to assume
893 very small values. Default is no.
895 .B key\-cache\-size: \fI<number>
896 Number of bytes size of the key cache. Default is 4 megabytes.
897 A plain number is in bytes, append 'k', 'm' or 'g' for kilobytes, megabytes
898 or gigabytes (1024*1024 bytes in a megabyte).
900 .B key\-cache\-slabs: \fI<number>
901 Number of slabs in the key cache. Slabs reduce lock contention by threads.
902 Must be set to a power of 2. Setting (close) to the number of cpus is a
905 .B neg\-cache\-size: \fI<number>
906 Number of bytes size of the aggressive negative cache. Default is 1 megabyte.
907 A plain number is in bytes, append 'k', 'm' or 'g' for kilobytes, megabytes
908 or gigabytes (1024*1024 bytes in a megabyte).
910 .B unblock\-lan\-zones: \fI<yesno>
911 Default is disabled. If enabled, then for private address space,
912 the reverse lookups are no longer filtered. This allows unbound when
913 running as dns service on a host where it provides service for that host,
914 to put out all of the queries for the 'lan' upstream. When enabled,
915 only localhost, 127.0.0.1 reverse and ::1 reverse zones are configured
916 with default local zones. Disable the option when unbound is running
917 as a (DHCP-) DNS network resolver for a group of machines, where such
918 lookups should be filtered (RFC compliance), this also stops potential
919 data leakage about the local network to the upstream DNS servers.
921 .B insecure\-lan\-zones: \fI<yesno>
922 Default is disabled. If enabled, then reverse lookups in private
923 address space are not validated. This is usually required whenever
924 \fIunblock\-lan\-zones\fR is used.
926 .B local\-zone: \fI<zone> <type>
927 Configure a local zone. The type determines the answer to give if
928 there is no match from local\-data. The types are deny, refuse, static,
929 transparent, redirect, nodefault, typetransparent, inform, inform_deny,
930 always_transparent, always_refuse, always_nxdomain,
931 and are explained below. After that the default settings are listed. Use
932 local\-data: to enter data into the local zone. Answers for local zones
933 are authoritative DNS answers. By default the zones are class IN.
935 If you need more complicated authoritative data, with referrals, wildcards,
936 CNAME/DNAME support, or DNSSEC authoritative service, setup a stub\-zone for
937 it as detailed in the stub zone section below.
940 Do not send an answer, drop the query.
941 If there is a match from local data, the query is answered.
944 Send an error message reply, with rcode REFUSED.
945 If there is a match from local data, the query is answered.
948 If there is a match from local data, the query is answered.
949 Otherwise, the query is answered with nodata or nxdomain.
950 For a negative answer a SOA is included in the answer if present
951 as local\-data for the zone apex domain.
953 \h'5'\fItransparent\fR
954 If there is a match from local data, the query is answered.
955 Otherwise if the query has a different name, the query is resolved normally.
956 If the query is for a name given in localdata but no such type of data is
957 given in localdata, then a noerror nodata answer is returned.
958 If no local\-zone is given local\-data causes a transparent zone
959 to be created by default.
961 \h'5'\fItypetransparent\fR
962 If there is a match from local data, the query is answered. If the query
963 is for a different name, or for the same name but for a different type,
964 the query is resolved normally. So, similar to transparent but types
965 that are not listed in local data are resolved normally, so if an A record
966 is in the local data that does not cause a nodata reply for AAAA queries.
969 The query is answered from the local data for the zone name.
970 There may be no local data beneath the zone name.
971 This answers queries for the zone, and all subdomains of the zone
972 with the local data for the zone.
973 It can be used to redirect a domain to return a different address record
974 to the end user, with
975 local\-zone: "example.com." redirect and
976 local\-data: "example.com. A 127.0.0.1"
977 queries for www.example.com and www.foo.example.com are redirected, so
978 that users with web browsers cannot access sites with suffix example.com.
981 The query is answered normally. The client IP address (@portnumber)
982 is printed to the logfile. The log message is: timestamp, unbound-pid,
983 info: zonename inform IP@port queryname type class. This option can be
984 used for normal resolution, but machines looking up infected names are
985 logged, eg. to run antivirus on them.
987 \h'5'\fIinform_deny\fR
988 The query is dropped, like 'deny', and logged, like 'inform'. Ie. find
989 infected machines without answering the queries.
991 \h'5'\fIalways_transparent\fR
992 Like transparent, but ignores local data and resolves normally.
994 \h'5'\fIalways_refuse\fR
995 Like refuse, but ignores local data and refuses the query.
997 \h'5'\fIalways_nxdomain\fR
998 Like static, but ignores local data and returns nxdomain for the query.
1000 \h'5'\fInodefault\fR
1001 Used to turn off default contents for AS112 zones. The other types
1002 also turn off default contents for the zone. The 'nodefault' option
1003 has no other effect than turning off default contents for the
1004 given zone. Use \fInodefault\fR if you use exactly that zone, if you want to
1005 use a subzone, use \fItransparent\fR.
1007 The default zones are localhost, reverse 127.0.0.1 and ::1, the onion and
1008 the AS112 zones. The AS112 zones are reverse DNS zones for private use and
1009 reserved IP addresses for which the servers on the internet cannot provide
1010 correct answers. They are configured by default to give nxdomain (no reverse
1011 information) answers. The defaults can be turned off by specifying your
1012 own local\-zone of that name, or using the 'nodefault' type. Below is a
1013 list of the default zone contents.
1015 \h'5'\fIlocalhost\fR
1016 The IP4 and IP6 localhost information is given. NS and SOA records are provided
1017 for completeness and to satisfy some DNS update tools. Default content:
1019 local\-zone: "localhost." static
1020 local\-data: "localhost. 10800 IN NS localhost."
1021 local\-data: "localhost. 10800 IN
1022 SOA localhost. nobody.invalid. 1 3600 1200 604800 10800"
1023 local\-data: "localhost. 10800 IN A 127.0.0.1"
1024 local\-data: "localhost. 10800 IN AAAA ::1"
1027 \h'5'\fIreverse IPv4 loopback\fR
1030 local\-zone: "127.in\-addr.arpa." static
1031 local\-data: "127.in\-addr.arpa. 10800 IN NS localhost."
1032 local\-data: "127.in\-addr.arpa. 10800 IN
1033 SOA localhost. nobody.invalid. 1 3600 1200 604800 10800"
1034 local\-data: "1.0.0.127.in\-addr.arpa. 10800 IN
1038 \h'5'\fIreverse IPv6 loopback\fR
1041 local\-zone: "1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.
1042 0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.ip6.arpa." static
1043 local\-data: "1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.
1044 0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.ip6.arpa. 10800 IN
1046 local\-data: "1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.
1047 0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.ip6.arpa. 10800 IN
1048 SOA localhost. nobody.invalid. 1 3600 1200 604800 10800"
1049 local\-data: "1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.
1050 0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.ip6.arpa. 10800 IN
1054 \h'5'\fIonion (RFC 7686)\fR
1057 local\-zone: "onion." static
1058 local\-data: "onion. 10800 IN NS localhost."
1059 local\-data: "onion. 10800 IN
1060 SOA localhost. nobody.invalid. 1 3600 1200 604800 10800"
1063 \h'5'\fIreverse RFC1918 local use zones\fR
1064 Reverse data for zones 10.in\-addr.arpa, 16.172.in\-addr.arpa to
1065 31.172.in\-addr.arpa, 168.192.in\-addr.arpa.
1066 The \fBlocal\-zone:\fR is set static and as \fBlocal\-data:\fR SOA and NS
1067 records are provided.
1069 \h'5'\fIreverse RFC3330 IP4 this, link\-local, testnet and broadcast\fR
1070 Reverse data for zones 0.in\-addr.arpa, 254.169.in\-addr.arpa,
1071 2.0.192.in\-addr.arpa (TEST NET 1), 100.51.198.in\-addr.arpa (TEST NET 2),
1072 113.0.203.in\-addr.arpa (TEST NET 3), 255.255.255.255.in\-addr.arpa.
1073 And from 64.100.in\-addr.arpa to 127.100.in\-addr.arpa (Shared Address Space).
1075 \h'5'\fIreverse RFC4291 IP6 unspecified\fR
1076 Reverse data for zone
1078 0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.
1079 0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.ip6.arpa.
1082 \h'5'\fIreverse RFC4193 IPv6 Locally Assigned Local Addresses\fR
1083 Reverse data for zone D.F.ip6.arpa.
1085 \h'5'\fIreverse RFC4291 IPv6 Link Local Addresses\fR
1086 Reverse data for zones 8.E.F.ip6.arpa to B.E.F.ip6.arpa.
1088 \h'5'\fIreverse IPv6 Example Prefix\fR
1089 Reverse data for zone 8.B.D.0.1.0.0.2.ip6.arpa. This zone is used for
1090 tutorials and examples. You can remove the block on this zone with:
1092 local\-zone: 8.B.D.0.1.0.0.2.ip6.arpa. nodefault
1094 You can also selectively unblock a part of the zone by making that part
1095 transparent with a local\-zone statement.
1096 This also works with the other default zones.
1097 .\" End of local-zone listing.
1099 .B local\-data: \fI"<resource record string>"
1100 Configure local data, which is served in reply to queries for it.
1101 The query has to match exactly unless you configure the local\-zone as
1102 redirect. If not matched exactly, the local\-zone type determines
1103 further processing. If local\-data is configured that is not a subdomain of
1104 a local\-zone, a transparent local\-zone is configured.
1105 For record types such as TXT, use single quotes, as in
1106 local\-data: 'example. TXT "text"'.
1108 If you need more complicated authoritative data, with referrals, wildcards,
1109 CNAME/DNAME support, or DNSSEC authoritative service, setup a stub\-zone for
1110 it as detailed in the stub zone section below.
1112 .B local\-data\-ptr: \fI"IPaddr name"
1113 Configure local data shorthand for a PTR record with the reversed IPv4 or
1114 IPv6 address and the host name. For example "192.0.2.4 www.example.com".
1115 TTL can be inserted like this: "2001:DB8::4 7200 www.example.com"
1117 .B local\-zone\-tag: \fI<zone> <"list of tags">
1118 Assign tags to localzones. Tagged localzones will only be applied when the
1119 used access-control element has a matching tag. Tags must be defined in
1120 \fIdefine\-tags\fR. Enclose list of tags in quotes ("") and put spaces between
1123 .B local\-zone\-override: \fI<zone> <IP netblock> <type>
1124 Override the localzone type for queries from addresses matching netblock.
1125 Use this localzone type, regardless the type configured for the local-zone
1126 (both tagged and untagged) and regardless the type configured using
1127 access\-control\-tag\-action.
1129 .B ratelimit: \fI<number or 0>
1130 Enable ratelimiting of queries sent to nameserver for performing recursion.
1131 If 0, the default, it is disabled. This option is experimental at this time.
1132 The ratelimit is in queries per second that are allowed. More queries are
1133 turned away with an error (servfail). This stops recursive floods, eg. random
1134 query names, but not spoofed reflection floods. Cached responses are not
1135 ratelimited by this setting. The zone of the query is determined by examining
1136 the nameservers for it, the zone name is used to keep track of the rate.
1137 For example, 1000 may be a suitable value to stop the server from being
1138 overloaded with random names, and keeps unbound from sending traffic to the
1139 nameservers for those zones.
1141 .B ratelimit\-size: \fI<memory size>
1142 Give the size of the data structure in which the current ongoing rates are
1143 kept track in. Default 4m. In bytes or use m(mega), k(kilo), g(giga).
1144 The ratelimit structure is small, so this data structure likely does
1145 not need to be large.
1147 .B ratelimit\-slabs: \fI<number>
1148 Give power of 2 number of slabs, this is used to reduce lock contention
1149 in the ratelimit tracking data structure. Close to the number of cpus is
1150 a fairly good setting.
1152 .B ratelimit\-factor: \fI<number>
1153 Set the amount of queries to rate limit when the limit is exceeded.
1154 If set to 0, all queries are dropped for domains where the limit is
1155 exceeded. If set to another value, 1 in that number is allowed through
1156 to complete. Default is 10, allowing 1/10 traffic to flow normally.
1157 This can make ordinary queries complete (if repeatedly queried for),
1158 and enter the cache, whilst also mitigating the traffic flow by the
1161 .B ratelimit\-for\-domain: \fI<domain> <number qps>
1162 Override the global ratelimit for an exact match domain name with the listed
1163 number. You can give this for any number of names. For example, for
1164 a top\-level\-domain you may want to have a higher limit than other names.
1166 .B ratelimit\-below\-domain: \fI<domain> <number qps>
1167 Override the global ratelimit for a domain name that ends in this name.
1168 You can give this multiple times, it then describes different settings
1169 in different parts of the namespace. The closest matching suffix is used
1170 to determine the qps limit. The rate for the exact matching domain name
1171 is not changed, use ratelimit\-for\-domain to set that, you might want
1172 to use different settings for a top\-level\-domain and subdomains.
1173 .SS "Remote Control Options"
1176 clause are the declarations for the remote control facility. If this is
1177 enabled, the \fIunbound\-control\fR(8) utility can be used to send
1178 commands to the running unbound server. The server uses these clauses
1179 to setup SSLv3 / TLSv1 security for the connection. The
1180 \fIunbound\-control\fR(8) utility also reads the \fBremote\-control\fR
1181 section for options. To setup the correct self\-signed certificates use the
1182 \fIunbound\-control\-setup\fR(8) utility.
1184 .B control\-enable: \fI<yes or no>
1185 The option is used to enable remote control, default is "no".
1186 If turned off, the server does not listen for control commands.
1188 .B control\-interface: \fI<ip address or path>
1189 Give IPv4 or IPv6 addresses or local socket path to listen on for
1191 By default localhost (127.0.0.1 and ::1) is listened to.
1192 Use 0.0.0.0 and ::0 to listen to all interfaces.
1193 If you change this and permissions have been dropped, you must restart
1194 the server for the change to take effect.
1196 .B control\-port: \fI<port number>
1197 The port number to listen on for IPv4 or IPv6 control interfaces,
1199 If you change this and permissions have been dropped, you must restart
1200 the server for the change to take effect.
1202 .B control\-use\-cert: \fI<yes or no>
1203 Whether to require certificate authentication of control connections.
1204 The default is "yes".
1205 This should not be changed unless there are other mechanisms in place
1206 to prevent untrusted users from accessing the remote control
1209 .B server\-key\-file: \fI<private key file>
1210 Path to the server private key, by default unbound_server.key.
1211 This file is generated by the \fIunbound\-control\-setup\fR utility.
1212 This file is used by the unbound server, but not by \fIunbound\-control\fR.
1214 .B server\-cert\-file: \fI<certificate file.pem>
1215 Path to the server self signed certificate, by default unbound_server.pem.
1216 This file is generated by the \fIunbound\-control\-setup\fR utility.
1217 This file is used by the unbound server, and also by \fIunbound\-control\fR.
1219 .B control\-key\-file: \fI<private key file>
1220 Path to the control client private key, by default unbound_control.key.
1221 This file is generated by the \fIunbound\-control\-setup\fR utility.
1222 This file is used by \fIunbound\-control\fR.
1224 .B control\-cert\-file: \fI<certificate file.pem>
1225 Path to the control client certificate, by default unbound_control.pem.
1226 This certificate has to be signed with the server certificate.
1227 This file is generated by the \fIunbound\-control\-setup\fR utility.
1228 This file is used by \fIunbound\-control\fR.
1229 .SS "Stub Zone Options"
1231 There may be multiple
1233 clauses. Each with a name: and zero or more hostnames or IP addresses.
1234 For the stub zone this list of nameservers is used. Class IN is assumed.
1235 The servers should be authority servers, not recursors; unbound performs
1236 the recursive processing itself for stub zones.
1238 The stub zone can be used to configure authoritative data to be used
1239 by the resolver that cannot be accessed using the public internet servers.
1240 This is useful for company\-local data or private zones. Setup an
1241 authoritative server on a different host (or different port). Enter a config
1242 entry for unbound with
1244 <ip address of host[@port]>.
1245 The unbound resolver can then access the data, without referring to the
1246 public internet for it.
1248 This setup allows DNSSEC signed zones to be served by that
1249 authoritative server, in which case a trusted key entry with the public key
1250 can be put in config, so that unbound can validate the data and set the AD
1251 bit on replies for the private zone (authoritative servers do not set the
1252 AD bit). This setup makes unbound capable of answering queries for the
1253 private zone, and can even set the AD bit ('authentic'), but the AA
1254 ('authoritative') bit is not set on these replies.
1256 Consider adding \fBserver:\fR statements for \fBdomain\-insecure:\fR and
1257 for \fBlocal\-zone:\fI name nodefault\fR for the zone if it is a locally
1258 served zone. The insecure clause stops DNSSEC from invalidating the
1259 zone. The local zone nodefault (or \fItransparent\fR) clause makes the
1260 (reverse\-) zone bypass unbound's filtering of RFC1918 zones.
1262 .B name: \fI<domain name>
1263 Name of the stub zone.
1265 .B stub\-host: \fI<domain name>
1266 Name of stub zone nameserver. Is itself resolved before it is used.
1268 .B stub\-addr: \fI<IP address>
1269 IP address of stub zone nameserver. Can be IP 4 or IP 6.
1270 To use a nondefault port for DNS communication append '@' with the port number.
1272 .B stub\-prime: \fI<yes or no>
1273 This option is by default off. If enabled it performs NS set priming,
1274 which is similar to root hints, where it starts using the list of nameservers
1275 currently published by the zone. Thus, if the hint list is slightly outdated,
1276 the resolver picks up a correct list online.
1278 .B stub\-first: \fI<yes or no>
1279 If enabled, a query is attempted without the stub clause if it fails.
1280 The data could not be retrieved and would have caused SERVFAIL because
1281 the servers are unreachable, instead it is tried without this clause.
1283 .SS "Forward Zone Options"
1285 There may be multiple
1287 clauses. Each with a \fBname:\fR and zero or more hostnames or IP
1288 addresses. For the forward zone this list of nameservers is used to
1289 forward the queries to. The servers listed as \fBforward\-host:\fR and
1290 \fBforward\-addr:\fR have to handle further recursion for the query. Thus,
1291 those servers are not authority servers, but are (just like unbound is)
1292 recursive servers too; unbound does not perform recursion itself for the
1293 forward zone, it lets the remote server do it. Class IN is assumed.
1294 A forward\-zone entry with name "." and a forward\-addr target will
1295 forward all queries to that other server (unless it can answer from
1298 .B name: \fI<domain name>
1299 Name of the forward zone.
1301 .B forward\-host: \fI<domain name>
1302 Name of server to forward to. Is itself resolved before it is used.
1304 .B forward\-addr: \fI<IP address>
1305 IP address of server to forward to. Can be IP 4 or IP 6.
1306 To use a nondefault port for DNS communication append '@' with the port number.
1308 .B forward\-first: \fI<yes or no>
1309 If enabled, a query is attempted without the forward clause if it fails.
1310 The data could not be retrieved and would have caused SERVFAIL because
1311 the servers are unreachable, instead it is tried without this clause.
1313 .SS "Python Module Options"
1317 clause gives the settings for the \fIpython\fR(1) script module. This module
1318 acts like the iterator and validator modules do, on queries and answers.
1319 To enable the script module it has to be compiled into the daemon,
1320 and the word "python" has to be put in the \fBmodule\-config:\fR option
1321 (usually first, or between the validator and iterator).
1323 .B python\-script: \fI<python file>\fR
1324 The script file to load.
1325 .SS "DNS64 Module Options"
1327 The dns64 module must be configured in the \fBmodule\-config:\fR "dns64
1328 validator iterator" directive and be compiled into the daemon to be
1329 enabled. These settings go in the \fBserver:\fR section.
1331 .B dns64\-prefix: \fI<IPv6 prefix>\fR
1332 This sets the DNS64 prefix to use to synthesize AAAA records with.
1333 It must be /96 or shorter. The default prefix is 64:ff9b::/96.
1335 .B dns64\-synthall: \fI<yes or no>\fR
1336 Debug option, default no. If enabled, synthesize all AAAA records
1337 despite the presence of actual AAAA records.
1338 .SH "MEMORY CONTROL EXAMPLE"
1339 In the example config settings below memory usage is reduced. Some service
1340 levels are lower, notable very large data and a high TCP load are no longer
1341 supported. Very large data and high TCP loads are exceptional for the DNS.
1342 DNSSEC validation is enabled, just add trust anchors.
1343 If you do not have to worry about programs using more than 3 Mb of memory,
1344 the below example is not for you. Use the defaults to receive full service,
1345 which on BSD\-32bit tops out at 30\-40 Mb after heavy usage.
1348 # example settings that reduce memory usage
1351 outgoing\-num\-tcp: 1 # this limits TCP service, uses less buffers.
1352 incoming\-num\-tcp: 1
1353 outgoing\-range: 60 # uses less memory, but less performance.
1354 msg\-buffer\-size: 8192 # note this limits service, 'no huge stuff'.
1355 msg\-cache\-size: 100k
1356 msg\-cache\-slabs: 1
1357 rrset\-cache\-size: 100k
1358 rrset\-cache\-slabs: 1
1359 infra\-cache\-numhosts: 200
1360 infra\-cache\-slabs: 1
1361 key\-cache\-size: 100k
1362 key\-cache\-slabs: 1
1363 neg\-cache\-size: 10k
1364 num\-queries\-per\-thread: 30
1365 target\-fetch\-policy: "2 1 0 0 0 0"
1366 harden\-large\-queries: "yes"
1367 harden\-short\-bufsize: "yes"
1372 default unbound working directory.
1379 .I /var/unbound/unbound.conf
1380 unbound configuration file.
1382 .I /var/unbound/unbound.pid
1383 default unbound pidfile with process ID of the running daemon.
1386 unbound log file. default is to log to
1390 \fIunbound\-checkconf\fR(8).
1393 was written by NLnet Labs. Please see CREDITS file
1394 in the distribution for further details.
projects / FreeBSD / FreeBSD.git / blob