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Upgrade guide for rec-4.3
[thirdparty/pdns.git] / pdns / recursordist / docs / settings.rst
1 PowerDNS Recursor Settings
2 ==========================
3 Each setting can appear on the command line, prefixed by '--', or in the configuration file.
4 The command line overrides the configuration file.
5
6 **Note**: Settings marked as 'Boolean' can either be set to an empty value, which means on, or to 'no' or 'off' which means off.
7 Anything else means on.
8
9 As an example:
10
11 - ``serve-rfc1918`` on its own means: do serve those zones.
12 - ``serve-rfc1918=off`` or ``serve-rfc1918=no`` means: do not serve those zones.
13 - Anything else means: do serve those zones.
14
15 .. _setting-allow-from:
16
17 ``allow-from``
18 --------------
19 - IP ranges, separated by commas
20 - Default: 10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16
21
22 Netmasks (both IPv4 and IPv6) that are allowed to use the server.
23 The default allows access only from :rfc:`1918` private IP addresses.
24 Due to the aggressive nature of the internet these days, it is highly recommended to not open up the recursor for the entire internet.
25 Questions from IP addresses not listed here are ignored and do not get an answer.
26
27 .. _setting-allow-from-file:
28
29 ``allow-from-file``
30 -------------------
31 - Path
32
33 Like `allow-from`_, except reading from file.
34 Overrides the `allow-from`_ setting. To use this feature, supply one netmask per line, with optional comments preceded by a "#".
35
36 .. _setting-any-to-tcp:
37
38 ``any-to-tcp``
39 --------------
40 - Boolean
41 - Default: no
42
43 Answer questions for the ANY type on UDP with a truncated packet that refers the remote server to TCP.
44 Useful for mitigating ANY reflection attacks.
45
46 .. _setting-allow-trust-anchor-query:
47
48 ``allow-trust-anchor-query``
49 ----------------------------
50 .. versionadded:: 4.3.0
51
52 - Boolean
53 - Default: no
54
55 Allow ``trustanchor.server CH TXT`` and ``negativetrustanchor.server CH TXT`` queries to view the configured :doc:`DNSSEC <dnssec>` (negative) trust anchors.
56
57 .. _setting-api-config-dir:
58
59 ``api-config-dir``
60 ------------------
61 .. versionadded:: 4.0.0
62
63 - Path
64 - Default: unset
65
66 Directory where the REST API stores its configuration and zones.
67
68 .. _setting-api-key:
69
70 ``api-key``
71 -----------
72 .. versionadded:: 4.0.0
73
74 - String
75 - Default: unset
76
77 Static pre-shared authentication key for access to the REST API.
78
79 .. _setting-api-readonly:
80
81 ``api-readonly``
82 ----------------
83 .. versionchanged:: 4.2.0
84 This setting has been removed.
85
86 - Boolean
87 - Default: no
88
89 Disallow data modification through the REST API when set.
90
91 .. _setting-api-logfile:
92
93 ``api-logfile``
94 ---------------
95 .. versionchanged:: 4.2.0
96 This setting has been removed.
97
98 - Path
99 - Default: unset
100
101 Location of the server logfile (used by the REST API).
102
103 .. _setting-auth-can-lower-ttl:
104
105 ``auth-can-lower-ttl``
106 ----------------------
107 - Boolean
108 - Default: no
109
110 Authoritative zones can transmit a TTL value that is lower than that specified in the parent zone.
111 This is called a 'delegation inconsistency'.
112 To follow :rfc:`RFC 2181 section 5.2<2181#section-5.2>` and :rfc:`5.4 <2181#section-5.4>` to the letter, enable this feature.
113 This will mean a slight deterioration of performance, and it will not solve any problems, but does make the recursor more standards compliant.
114 Not recommended unless you have to tick an 'RFC 2181 compliant' box.
115
116 .. _setting-auth-zones:
117
118 ``auth-zones``
119 --------------
120 - Comma separated list of 'zonename=filename' pairs
121
122 Zones read from these files (in BIND format) are served authoritatively.
123 DNSSEC is not supported. Example:
124
125 .. code-block:: none
126
127 auth-zones=example.org=/var/zones/example.org, powerdns.com=/var/zones/powerdns.com
128
129 .. _setting-carbon-interval:
130
131 ``carbon-interval``
132 -------------------
133 - Integer
134 - Default: 30
135
136 If sending carbon updates, this is the interval between them in seconds.
137 See :doc:`metrics`.
138
139 .. _setting-carbon-namespace:
140
141 ``carbon-namespace``
142 --------------------
143 .. versionadded:: 4.2.0
144
145 - String
146
147 Change the namespace or first string of the metric key. The default is pdns.
148
149 .. _setting-carbon-ourname:
150
151 ``carbon-ourname``
152 ------------------
153 - String
154
155 If sending carbon updates, if set, this will override our hostname.
156 Be careful not to include any dots in this setting, unless you know what you are doing.
157 See :ref:`metricscarbon`.
158
159 .. _setting-carbon-instance:
160
161 ``carbon-instance``
162 --------------------
163 .. versionadded:: 4.2.0
164
165 - String
166
167 Change the instance or third string of the metric key. The default is recursor.
168
169 .. _setting-carbon-server:
170
171 ``carbon-server``
172 -----------------
173 - IP address
174
175 If set to an IP or IPv6 address, will send all available metrics to this server via the carbon protocol, which is used by graphite and metronome. Moreover you can specify more than one server using a comma delimited list, ex: carbon-server=10.10.10.10,10.10.10.20.
176 You may specify an alternate port by appending :port, for example: ``127.0.0.1:2004``.
177 See :doc:`metrics`.
178
179 .. _setting-chroot:
180
181 ``chroot``
182 ----------
183 - Path to a Directory
184
185 If set, chroot to this directory for more security.
186 See :doc:`security`
187
188 Make sure that ``/dev/log`` is available from within the chroot.
189 Logging will silently fail over time otherwise (on logrotate).
190
191 When using ``chroot``, all other paths (except for `config-dir`_) set in the configuration are relative to the new root.
192
193 When using ``chroot`` and the API (`webserver`_), `api-readonly`_ **must** be set and `api-config-dir`_ unset.
194
195 When running on a system where systemd manages services, ``chroot`` does not work out of the box, as PowerDNS cannot use the ``NOTIFY_SOCKET``.
196 Either do not ``chroot`` on these systems or set the 'Type' of this service to 'simple' instead of 'notify' (refer to the systemd documentation on how to modify unit-files).
197
198 .. _setting-client-tcp-timeout:
199
200 ``client-tcp-timeout``
201 ----------------------
202 - Integer
203 - Default: 2
204
205 Time to wait for data from TCP clients.
206
207 .. _setting-config-dir:
208
209 ``config-dir``
210 --------------
211 - Path
212
213 Location of configuration directory (``recursor.conf``).
214 Usually ``/etc/powerdns``, but this depends on ``SYSCONFDIR`` during compile-time.
215
216 .. _setting-config-name:
217
218 ``config-name``
219 ---------------
220 - String
221 - Default: unset
222
223 When running multiple recursors on the same server, read settings from :file:`recursor-{name}.conf`, this will also rename the binary image.
224
225 .. _setting-cpu-map:
226
227 ``cpu-map``
228 -----------
229 .. versionadded:: 4.1.0
230
231 - String
232 - Default: unset
233
234 Set CPU affinity for worker threads, asking the scheduler to run those threads on a single CPU, or a set of CPUs.
235 This parameter accepts a space separated list of thread-id=cpu-id, or thread-id=cpu-id-1,cpu-id-2,...,cpu-id-N.
236 For example, to make the worker thread 0 run on CPU id 0 and the worker thread 1 on CPUs 1 and 2::
237
238 cpu-map=0=0 1=1,2
239
240 The number of worker threads is determined by the :ref:`setting-threads` setting.
241 If :ref:`setting-pdns-distributes-queries` is set, an additional thread is started, assigned the id 0,
242 and is the only one listening on client sockets and accepting queries, distributing them to the other worker threads afterwards.
243
244 Starting with version 4.2.0, the thread handling the control channel, the webserver and other internal stuff has been assigned
245 id 0 and more than one distributor thread can be started using the :ref:`setting-distributor-threads` setting, so the distributor
246 threads if any are assigned id 1 and counting, and the other threads follow behind.
247
248 This parameter is only available on OS that provides the `pthread_setaffinity_np()` function.
249
250 .. _setting-daemon:
251
252 ``daemon``
253 ----------
254 - Boolean
255 - Default: no
256
257 .. versionchanged:: 4.0.0
258
259 Default is now "no", was "yes" before.
260
261 Operate in the background.
262
263 .. _setting-delegation-only:
264
265 ``delegation-only``
266 -------------------
267 - Domains, comma separated
268
269 Which domains we only accept delegations from (a Verisign special).
270
271 .. _setting-dont-throttle-names:
272
273 ``dont-throttle-names``
274 ----------------------------
275 .. versionadded:: 4.2.0
276
277 - Comma separated list of domain-names
278 - Default: (empty)
279
280 When an authoritative server does not answer a query or sends a reply the recursor does not like, it is throttled.
281 Any servers' name suffix-matching the supplied names will never be throttled.
282
283 .. warning::
284 Most servers on the internet do not respond for a good reason (overloaded or unreachable), ``dont-throttle-names`` could make this load on the upstream server even higher, resulting in further service degradation.
285
286 .. _setting-dont-throttle-netmasks:
287
288 ``dont-throttle-netmasks``
289 ----------------------------
290 .. versionadded:: 4.2.0
291
292 - Comma separated list of netmasks
293 - Default: (empty)
294
295 When an authoritative server does not answer a query or sends a reply the recursor does not like, it is throttled.
296 Any servers matching the supplied netmasks will never be throttled.
297
298 This can come in handy on lossy networks when forwarding, where the same server is configured multiple times (e.g. with ``forward-zones-recurse=example.com=192.0.2.1;192.0.2.1``).
299 By default, the PowerDNS Recursor would throttle the "first" server on a timeout and hence not retry the "second" one.
300 In this case, ``dont-throttle-netmasks`` could be set to ``192.0.2.1``.
301
302 .. warning::
303 Most servers on the internet do not respond for a good reason (overloaded or unreachable), ``dont-throttle-netmasks`` could make this load on the upstream server even higher, resulting in further service degradation.
304
305 .. _setting-disable-packetcache:
306
307 ``disable-packetcache``
308 -----------------------
309 - Boolean
310 - Default: no
311
312 Turn off the packet cache. Useful when running with Lua scripts that can
313 not be cached.
314
315 .. _setting-disable-syslog:
316
317 ``disable-syslog``
318 ------------------
319 - Boolean
320 - Default: no
321
322 Do not log to syslog, only to stdout.
323 Use this setting when running inside a supervisor that handles logging (like systemd).
324 **Note**: do not use this setting in combination with `daemon`_ as all logging will disappear.
325
326 .. _setting-distribution-load-factor:
327
328 ``distribution-load-factor``
329 ----------------------------
330 .. versionadded:: 4.1.12
331
332 - Double
333 - Default: 0.0
334
335 If `pdns-distributes-queries`_ is set and this setting is set to another value
336 than 0, the distributor thread will use a bounded load-balancing algorithm while
337 distributing queries to worker threads, making sure that no thread is assigned
338 more queries than distribution-load-factor times the average number of queries
339 currently processed by all the workers.
340 For example, with a value of 1.25, no server should get more than 125 % of the
341 average load. This helps making sure that all the workers have roughly the same
342 share of queries, even if the incoming traffic is very skewed, with a larger
343 number of requests asking for the same qname.
344
345 .. _setting-distribution-pipe-buffer-size:
346
347 ``distribution-pipe-buffer-size``
348 ---------------------------------
349 .. versionadded:: 4.2.0
350
351 - Integer
352 - Default: 0
353
354 Size in bytes of the internal buffer of the pipe used by the distributor to pass incoming queries to a worker thread.
355 Requires support for `F_SETPIPE_SZ` which is present in Linux since 2.6.35. The actual size might be rounded up to
356 a multiple of a page size. 0 means that the OS default size is used.
357 A large buffer might allow the recursor to deal with very short-lived load spikes during which a worker thread gets
358 overloaded, but it will be at the cost of an increased latency.
359
360 .. _setting-distributor-threads:
361
362 ``distributor-threads``
363 -----------------------
364 .. versionadded:: 4.2.0
365
366 - Integer
367 - Default: 1 if `pdns-distributes-queries`_ is set, 0 otherwise
368
369 If `pdns-distributes-queries`_ is set, spawn this number of distributor threads on startup. Distributor threads
370 handle incoming queries and distribute them to other threads based on a hash of the query, to maximize the cache hit
371 ratio.
372
373 .. _setting-dnssec:
374
375 ``dnssec``
376 ----------
377 .. versionadded:: 4.0.0
378
379 - One of ``off``, ``process-no-validate``, ``process``, ``log-fail``, ``validate``, String
380 - Default: ``process-no-validate``
381
382 Set the mode for DNSSEC processing:
383
384 off
385 ^^^
386 No DNSSEC processing whatsoever.
387 Ignore DO-bits in queries, don't request any DNSSEC information from authoritative servers.
388 This behaviour is similar to PowerDNS Recursor pre-4.0.
389
390 process-no-validate
391 ^^^^^^^^^^^^^^^^^^^
392 Respond with DNSSEC records to clients that ask for it, set the DO bit on all outgoing queries.
393 Don't do any validation.
394
395 process
396 ^^^^^^^
397 Respond with DNSSEC records to clients that ask for it, set the DO bit on all outgoing queries.
398 Do validation for clients that request it (by means of the AD- bit or DO-bit in the query).
399
400 log-fail
401 ^^^^^^^^
402 Similar behaviour to ``process``, but validate RRSIGs on responses and log bogus responses.
403
404 validate
405 ^^^^^^^^
406 Full blown DNSSEC validation. Send SERVFAIL to clients on bogus responses.
407
408 .. _setting-dnssec-log-bogus:
409
410 ``dnssec-log-bogus``
411 --------------------
412 - Boolean
413 - Default: no
414
415 Log every DNSSEC validation failure.
416 **Note**: This is not logged per-query but every time records are validated as Bogus.
417
418 .. _setting-dont-query:
419
420 ``dont-query``
421 --------------
422 - Netmasks, comma separated
423 - Default: 127.0.0.0/8, 10.0.0.0/8, 100.64.0.0/10, 169.254.0.0/16, 192.168.0.0/16, 172.16.0.0/12, ::1/128, fc00::/7, fe80::/10, 0.0.0.0/8, 192.0.0.0/24, 192.0.2.0/24, 198.51.100.0/24, 203.0.113.0/24, 240.0.0.0/4, ::/96, ::ffff:0:0/96, 100::/64, 2001:db8::/32
424
425 The DNS is a public database, but sometimes contains delegations to private IP addresses, like for example 127.0.0.1.
426 This can have odd effects, depending on your network, and may even be a security risk.
427 Therefore, the PowerDNS Recursor by default does not query private space IP addresses.
428 This setting can be used to expand or reduce the limitations.
429
430 Queries to addresses for zones as configured in any of the settings `forward-zones`_, `forward-zones-file`_ or `forward-zones-recurse`_ are performed regardless of these limitations.
431
432 .. _setting-ecs-add-for:
433
434 ``ecs-add-for``
435 ---------------
436 .. versionadded:: 4.2.0
437
438 - Comma separated list of netmasks
439 - Default: 0.0.0.0/0, ::, !127.0.0.0/8, !10.0.0.0/8, !100.64.0.0/10, !169.254.0.0/16, !192.168.0.0/16, !172.16.0.0/12, !::1/128, !fc00::/7, !fe80::/10
440
441 List of requestor netmasks for which the requestor IP Address should be used as the :rfc:`EDNS Client Subnet <7871>` for outgoing queries. Outgoing queries for requestors that do not match this list will use the `ecs-scope-zero-address`_ instead.
442 Valid incoming ECS values from `use-incoming-edns-subnet`_ are not replaced.
443
444 Regardless of the value of this setting, ECS values are only sent for outgoing queries matching the conditions in the `edns-subnet-whitelist`_ setting. This setting only controls the actual value being sent.
445
446 This defaults to not using the requestor address inside RFC1918 and similar "private" IP address spaces.
447
448 .. _setting-ecs-ipv4-bits:
449
450 ``ecs-ipv4-bits``
451 -----------------
452 .. versionadded:: 4.1.0
453
454 - Integer
455 - Default: 24
456
457 Number of bits of client IPv4 address to pass when sending EDNS Client Subnet address information.
458
459 .. _setting-ecs-ipv4-cache-bits:
460
461 ``ecs-ipv4-cache-bits``
462 -----------------------
463 .. versionadded:: 4.1.12
464
465 - Integer
466 - Default: 24
467
468 Maximum number of bits of client IPv4 address used by the authoritative server (as indicated by the EDNS Client Subnet scope in the answer) for an answer to be inserted into the query cache. This condition applies in conjunction with ``ecs-cache-limit-ttl``.
469 That is, only if both the limits apply, the record will not be cached.
470
471 .. _setting-ecs-ipv6-bits:
472
473 ``ecs-ipv6-bits``
474 -----------------
475 .. versionadded:: 4.1.0
476
477 - Integer
478 - Default: 56
479
480 Number of bits of client IPv6 address to pass when sending EDNS Client Subnet address information.
481
482 .. _setting-ecs-ipv6-cache-bits:
483
484 ``ecs-ipv6-cache-bits``
485 -----------------------
486 .. versionadded:: 4.1.12
487
488 - Integer
489 - Default: 56
490
491 Maximum number of bits of client IPv6 address used by the authoritative server (as indicated by the EDNS Client Subnet scope in the answer) for an answer to be inserted into the query cache. This condition applies in conjunction with ``ecs-cache-limit-ttl``.
492 That is, only if both the limits apply, the record will not be cached.
493
494 .. _setting-ecs-minimum-ttl-override:
495
496 ``ecs-minimum-ttl-override``
497 ----------------------------
498 - Integer
499 - Default: 0 (disabled)
500
501 This setting artificially raises the TTLs of records in the ANSWER section of ECS-specific answers to be at least this long.
502 While this is a gross hack, and violates RFCs, under conditions of DoS, it may enable you to continue serving your customers.
503 Can be set at runtime using ``rec_control set-ecs-minimum-ttl 3600``.
504
505 .. _setting-ecs-cache-limit-ttl:
506
507 ``ecs-cache-limit-ttl``
508 -----------------------
509 .. versionadded:: 4.1.12
510
511 - Integer
512 - Default: 0 (disabled)
513
514 The minimum TTL for an ECS-specific answer to be inserted into the query cache. This condition applies in conjunction with ``ecs-ipv4-cache-bits`` or ``ecs-ipv6-cache-bits``.
515 That is, only if both the limits apply, the record will not be cached.
516
517 .. _setting-ecs-scope-zero-address:
518
519 ``ecs-scope-zero-address``
520 --------------------------
521 .. versionadded:: 4.1.0
522
523 - IPv4 or IPv6 Address
524 - Default: empty
525
526 The IP address sent via EDNS Client Subnet to authoritative servers listed in
527 `edns-subnet-whitelist`_ when `use-incoming-edns-subnet`_ is set and the query has
528 an ECS source prefix-length set to 0.
529 The default is to look for the first usable (not an ``any`` one) address in
530 `query-local-address`_ then `query-local-address6`_. If no suitable address is
531 found, the recursor fallbacks to sending 127.0.0.1.
532
533 .. _setting-edns-outgoing-bufsize:
534
535 ``edns-outgoing-bufsize``
536 -------------------------
537 .. versionchanged:: 4.2.0
538 Before 4.2.0, the default was 1680
539
540 - Integer
541 - Default: 1232
542
543 .. note:: Why 1232?
544
545 1232 is the largest number of payload bytes that can fit in the smallest IPv6 packet.
546 IPv6 has a minimum MTU of 1280 bytes (:rfc:`RFC 8200, section 5 <8200#section-5>`), minus 40 bytes for the IPv6 header, minus 8 bytes for the UDP header gives 1232, the maximum payload size for the DNS response.
547
548 This is the value set for the EDNS0 buffer size in outgoing packets.
549 Lower this if you experience timeouts.
550
551 .. _setting-edns-subnet-whitelist:
552
553 ``edns-subnet-whitelist``
554 -------------------------
555 - Comma separated list of domain names and netmasks
556 - Default: (none)
557
558 List of netmasks and domains that :rfc:`EDNS Client Subnet <7871>` should be enabled for in outgoing queries.
559
560 For example, an EDNS Client Subnet option containing the address of the initial requestor (but see `ecs-add-for`_) will be added to an outgoing query sent to server 192.0.2.1 for domain X if 192.0.2.1 matches one of the supplied netmasks, or if X matches one of the supplied domains.
561 The initial requestor address will be truncated to 24 bits for IPv4 (see `ecs-ipv4-bits`_) and to 56 bits for IPv6 (see `ecs-ipv6-bits`_), as recommended in the privacy section of RFC 7871.
562
563 By default, this option is empty, meaning no EDNS Client Subnet information is sent.
564
565 .. _setting-entropy-source:
566
567 ``entropy-source``
568 ------------------
569 - Path
570 - Default: /dev/urandom
571
572 PowerDNS can read entropy from a (hardware) source.
573 This is used for generating random numbers which are very hard to predict.
574 Generally on UNIX platforms, this source will be ``/dev/urandom``, which will always supply random numbers, even if entropy is lacking.
575 Change to ``/dev/random`` if PowerDNS should block waiting for enough entropy to arrive.
576
577 .. _setting-etc-hosts-file:
578
579 ``etc-hosts-file``
580 ------------------
581 - Path
582 - Default: /etc/hosts
583
584 The path to the /etc/hosts file, or equivalent.
585 This file can be used to serve data authoritatively using `export-etc-hosts`_.
586
587 .. _setting-export-etc-hosts:
588
589 ``export-etc-hosts``
590 --------------------
591 - Boolean
592 - Default: no
593
594 If set, this flag will export the host names and IP addresses mentioned in ``/etc/hosts``.
595
596 .. _setting-export-etc-hosts-search-suffix:
597
598 ``export-etc-hosts-search-suffix``
599 ----------------------------------
600 - String
601
602 If set, all hostnames in the `export-etc-hosts`_ file are loaded in canonical form, based on this suffix, unless the name contains a '.', in which case the name is unchanged.
603 So an entry called 'pc' with ``export-etc-hosts-search-suffix='home.com'`` will lead to the generation of 'pc.home.com' within the recursor.
604 An entry called 'server1.home' will be stored as 'server1.home', regardless of this setting.
605
606 .. _setting-forward-zones:
607
608 ``forward-zones``
609 -----------------
610 - 'zonename=IP' pairs, comma separated
611
612 Queries for zones listed here will be forwarded to the IP address listed. i.e.
613
614 .. code-block:: none
615
616 forward-zones=example.org=203.0.113.210, powerdns.com=2001:DB8::BEEF:5
617
618 Multiple IP addresses can be specified and port numbers other than 53 can be configured:
619
620 .. code-block:: none
621
622 forward-zones=example.org=203.0.113.210:5300;127.0.0.1, powerdns.com=127.0.0.1;198.51.100.10:530;[2001:DB8::1:3]:5300
623
624 Forwarded queries have the 'recursion desired' bit set to 0, meaning that this setting is intended to forward queries to authoritative servers.
625
626 **IMPORTANT**: When using DNSSEC validation (which is default), forwards to non-delegated (e.g. internal) zones that have a DNSSEC signed parent zone will validate as Bogus.
627 To prevent this, add a Negative Trust Anchor (NTA) for this zone in the `lua-config-file`_ with ``addNTA("your.zone", "A comment")``.
628 If this forwarded zone is signed, instead of adding NTA, add the DS record to the `lua-config-file`_.
629 See the :doc:`dnssec` information.
630
631 .. _setting-forward-zones-file:
632
633 ``forward-zones-file``
634 ----------------------
635 - Path
636
637 Same as `forward-zones`_, parsed from a file. Only 1 zone is allowed per line, specified as follows:
638
639 .. code-block:: none
640
641 example.org=203.0.113.210, 192.0.2.4:5300
642
643 Zones prefixed with a '+' are forwarded with the recursion-desired bit set, for which see `forward-zones-recurse`_.
644 Default behaviour without '+' is as with `forward-zones`_.
645
646 .. versionchanged:: 4.0.0
647
648 Comments are allowed, everything behind '#' is ignored.
649
650 The DNSSEC notes from `forward-zones`_ apply here as well.
651
652 .. _setting-forward-zones-recurse:
653
654 ``forward-zones-recurse``
655 -------------------------
656 - 'zonename=IP' pairs, comma separated
657
658 Like regular `forward-zones`_, but forwarded queries have the 'recursion desired' bit set to 1, meaning that this setting is intended to forward queries to other recursive servers.
659
660 The DNSSEC notes from `forward-zones`_ apply here as well.
661
662 .. _setting-gettag-needs-edns-options:
663
664 ``gettag-needs-edns-options``
665 -----------------------------
666 .. versionadded:: 4.1.0
667
668 - Boolean
669 - Default: no
670
671 If set, EDNS options in incoming queries are extracted and passed to the :func:`gettag` hook in the ``ednsoptions`` table.
672
673 .. _setting-hint-file:
674
675 ``hint-file``
676 -------------
677 - Path
678
679 If set, the root-hints are read from this file. If unset, default root hints are used.
680
681 .. _setting-include-dir:
682
683 ``include-dir``
684 ---------------
685 - Path
686
687 Directory to scan for additional config files. All files that end with .conf are loaded in order using ``POSIX`` as locale.
688
689 .. _setting-latency-statistic-size:
690
691 ``latency-statistic-size``
692 --------------------------
693 - Integer
694 - Default: 10000
695
696 Indication of how many queries will be averaged to get the average latency reported by the 'qa-latency' metric.
697
698 .. _setting-local-address:
699
700 ``local-address``
701 -----------------
702 - IP addresses, comma separated
703 - Default: 127.0.0.1
704
705 Local IPv4 or IPv6 addresses to bind to.
706 Addresses can also contain port numbers, for IPv4 specify like this: ``192.0.2.4:5300``, for IPv6: ``[::1]:5300``.
707
708 **Warning**: When binding to wildcard addresses, UNIX semantics mean that answers may not be sent from the address a query was received on.
709 It is highly recommended to bind to explicit addresses.
710
711 .. _setting-local-port:
712
713 ``local-port``
714 --------------
715 - Integer
716 - Default: 53
717
718 Local port to bind to.
719 If an address in `local-address`_ does not have an explicit port, this port is used.
720
721 .. _setting-log-timestamp:
722
723 ``log-timestamp``
724 -----------------
725
726 .. versionadded:: 4.1.0
727
728 - Bool
729 - Default: yes
730
731 When printing log lines to stdout, prefix them with timestamps.
732 Disable this if the process supervisor timestamps these lines already.
733
734 .. note::
735 The systemd unit file supplied with the source code already disables timestamp printing
736
737 .. _setting-non-local-bind:
738
739 ``non-local-bind``
740 ------------------
741 - Boolean
742 - Default: no
743
744 Bind to addresses even if one or more of the `local-address`_'s do not exist on this server.
745 Setting this option will enable the needed socket options to allow binding to non-local addresses.
746 This feature is intended to facilitate ip-failover setups, but it may also mask configuration issues and for this reason it is disabled by default.
747
748 .. _setting-loglevel:
749
750 ``loglevel``
751 ------------
752 - Integer between 0 and 9
753 - Default: 6
754
755 Amount of logging.
756 Higher is more, more logging may destroy performance.
757 It is recommended not to set this below 3.
758
759 .. _setting-log-common-errors:
760
761 ``log-common-errors``
762 ---------------------
763 - Boolean
764 - Default: no
765
766 Some DNS errors occur rather frequently and are no cause for alarm.
767
768 ``log-rpz-changes``
769 -------------------
770 .. versionadded:: 4.1.0
771
772 - Boolean
773 - Default: no
774
775 Log additions and removals to RPZ zones at Info (6) level instead of Debug (7).
776
777 .. _setting-logging-facility:
778
779 ``logging-facility``
780 --------------------
781 - Integer
782
783 If set to a digit, logging is performed under this LOCAL facility.
784 See :ref:`logging`.
785 Do not pass names like 'local0'!
786
787 .. _setting-lowercase-outgoing:
788
789 ``lowercase-outgoing``
790 ----------------------
791 - Boolean
792 - Default: no
793
794 Set to true to lowercase the outgoing queries.
795 When set to 'no' (the default) a query from a client using mixed case in the DNS labels (such as a user entering mixed-case names or `draft-vixie-dnsext-dns0x20-00 <http://tools.ietf.org/html/draft-vixie-dnsext-dns0x20-00>`_), PowerDNS preserves the case of the query.
796 Broken authoritative servers might give a wrong or broken answer on this encoding.
797 Setting ``lowercase-outgoing`` to 'yes' makes the PowerDNS Recursor lowercase all the labels in the query to the authoritative servers, but still return the proper case to the client requesting.
798
799 .. _setting-lua-config-file:
800
801 ``lua-config-file``
802 -------------------
803 - Filename
804
805 If set, and Lua support is compiled in, this will load an additional configuration file for newer features and more complicated setups.
806 See :doc:`lua-config/index` for the options that can be set in this file.
807
808 .. _setting-lua-dns-script:
809
810 ``lua-dns-script``
811 ------------------
812 - Path
813 - Default: unset
814
815 Path to a lua file to manipulate the Recursor's answers. See :doc:`lua-scripting/index` for more information.
816
817 .. _setting-maintenance-interval:
818
819 ``lua-maintenance-interval``
820 ----------------------------
821 .. versionadded:: 4.2.0
822
823 - Integer
824 - Default: 1
825
826
827 The interval between calls to the Lua user defined `maintenance()` function in seconds.
828 See :ref:`hooks-maintenance-callback`
829
830 .. _setting-max-cache-bogus-ttl:
831
832 ``max-cache-bogus-ttl``
833 -----------------------
834 .. versionadded:: 4.2.0
835
836 - Integer
837 - Default: 3600
838
839 Maximum number of seconds to cache an item in the DNS cache (negative or positive) if its DNSSEC validation failed, no matter what the original TTL specified, to reduce the impact of a broken domain.
840
841 .. _setting-max-cache-entries:
842
843 ``max-cache-entries``
844 ---------------------
845 - Integer
846 - Default: 1000000
847
848 Maximum number of DNS cache entries.
849 1 million per thread will generally suffice for most installations.
850
851 .. _setting-max-cache-ttl:
852
853 ``max-cache-ttl``
854 -----------------
855 - Integer
856 - Default: 86400
857
858 Maximum number of seconds to cache an item in the DNS cache, no matter what the original TTL specified.
859
860 .. versionchanged:: 4.1.0
861
862 The minimum value of this setting is 15. i.e. setting this to lower than 15 will make this value 15.
863
864 .. _setting max-concurrent-requests-per-tcp-connection:
865
866 ``max-concurrent-requests-per-tcp-connection``
867 ----------------------------------------------
868
869 .. versionadded:: 4.3.0
870
871 - Integer
872 - Default: 10
873
874 Maximum number of incoming requests handled concurrently per tcp
875 connection. This number must be larger than 0 and smaller than 65536
876 and also smaller than `max-mthreads`.
877
878 .. _setting-max-generate-steps:
879
880 ``max-generate-steps``
881 ----------------------
882
883 .. versionadded:: 4.3.0
884
885 - Integer
886 - Default: 0
887
888 Maximum number of steps for a '$GENERATE' directive when parsing a
889 zone file. This is a protection measure to prevent consuming a lot of
890 CPU and memory when untrusted zones are loaded. Default to 0 which
891 means unlimited.
892
893 .. _setting-max-mthreads:
894
895 ``max-mthreads``
896 ----------------
897 - Integer
898 - Default: 2048
899
900 Maximum number of simultaneous MTasker threads.
901
902 .. _setting-max-packetcache-entries:
903
904 ``max-packetcache-entries``
905 ---------------------------
906 - Integer
907 - Default: 500000
908
909 Maximum number of Packet Cache entries.
910 1 million per thread will generally suffice for most installations.
911
912 .. _setting-max-qperq:
913
914 ``max-qperq``
915 -------------
916 - Integer
917 - Default: 50
918
919 The maximum number of outgoing queries that will be sent out during the resolution of a single client query.
920 This is used to limit endlessly chasing CNAME redirections.
921
922 .. _setting-max-negative-ttl:
923
924 ``max-negative-ttl``
925 --------------------
926 - Integer
927 - Default: 3600
928
929 A query for which there is authoritatively no answer is cached to quickly deny a record's existence later on, without putting a heavy load on the remote server.
930 In practice, caches can become saturated with hundreds of thousands of hosts which are tried only once.
931 This setting, which defaults to 3600 seconds, puts a maximum on the amount of time negative entries are cached.
932
933 .. _setting-max-recursion-depth:
934
935 ``max-recursion-depth``
936 -----------------------
937 - Integer
938 - Default: 40
939
940 Total maximum number of internal recursion calls the server may use to answer a single query.
941 0 means unlimited.
942 The value of `stack-size`_ should be increased together with this one to prevent the stack from overflowing.
943
944 .. versionchanged:: 4.1.0
945
946 Before 4.1.0, this settings was unlimited.
947
948 .. _setting-max-tcp-clients:
949
950 ``max-tcp-clients``
951 -------------------
952 - Integer
953 - Default: 128
954
955 Maximum number of simultaneous incoming TCP connections allowed.
956
957 .. _setting-max-tcp-per-client:
958
959 ``max-tcp-per-client``
960 ----------------------
961 - Integer
962 - Default: 0 (unlimited)
963
964 Maximum number of simultaneous incoming TCP connections allowed per client (remote IP address).
965
966 .. _setting-max-tcp-queries-per-connection:
967
968 ``max-tcp-queries-per-connection``
969 ----------------------------------
970 .. versionadded:: 4.1.0
971
972 - Integer
973 - Default: 0 (unlimited)
974
975 Maximum number of DNS queries in a TCP connection.
976
977 .. _setting-max-total-msec:
978
979 ``max-total-msec``
980 ------------------
981 - Integer
982 - Default: 7000
983
984 Total maximum number of milliseconds of wallclock time the server may use to answer a single query.
985
986 .. _setting-max-udp-queries-per-round:
987
988 ``max-udp-queries-per-round``
989 ----------------------------------
990 .. versionadded:: 4.1.4
991
992 - Integer
993 - Default: 10000
994
995 Under heavy load the recursor might be busy processing incoming UDP queries for a long while before there is no more of these, and might therefore
996 neglect scheduling new ``mthreads``, handling responses from authoritative servers or responding to :doc:`rec_control <manpages/rec_control.1>`
997 requests.
998 This setting caps the maximum number of incoming UDP DNS queries processed in a single round of looping on ``recvmsg()`` after being woken up by the multiplexer, before
999 returning back to normal processing and handling other events.
1000
1001 .. _setting-minimum-ttl-override:
1002
1003 ``minimum-ttl-override``
1004 ------------------------
1005 - Integer
1006 - Default: 0 (disabled)
1007
1008 This setting artificially raises all TTLs to be at least this long.
1009 While this is a gross hack, and violates RFCs, under conditions of DoS, it may enable you to continue serving your customers.
1010 Can be set at runtime using ``rec_control set-minimum-ttl 3600``.
1011
1012 .. _setting-new-domain-tracking:
1013
1014 ``new-domain-tracking``
1015 -----------------------
1016 .. versionadded:: 4.2.0
1017
1018 - Boolean
1019 - Default: no (disabled)
1020
1021 Whether to track newly observed domains, i.e. never seen before. This
1022 is a probablistic algorithm, using a stable bloom filter to store
1023 records of previously seen domains. When enabled for the first time,
1024 all domains will appear to be newly observed, so the feature is best
1025 left enabled for e.g. a week or longer before using the results. Note
1026 that this feature is optional and must be enabled at compile-time,
1027 thus it may not be available in all pre-built packages.
1028 If protobuf is enabled and configured, then the newly observed domain
1029 status will appear as a flag in Response messages.
1030
1031 .. _setting-new-domain-log:
1032
1033 ``new-domain-log``
1034 ------------------
1035 .. versionadded:: 4.2.0
1036
1037 - Boolean
1038 - Default: yes (enabled)
1039
1040 If a newly observed domain is detected, log that domain in the
1041 recursor log file. The log line looks something like::
1042
1043 Jul 18 11:31:25 Newly observed domain nod=sdfoijdfio.com
1044
1045 .. _setting-new-domain-lookup:
1046
1047 ``new-domain-lookup``
1048 ---------------------
1049 .. versionadded:: 4.2.0
1050
1051 - Domain Name
1052 - Example: nod.powerdns.com
1053
1054 If a domain is specified, then each time a newly observed domain is
1055 detected, the recursor will perform an A record lookup of "<newly
1056 observed domain>.<lookup domain>". For example if 'new-domain-lookup'
1057 is configured as 'nod.powerdns.com', and a new domain 'xyz123.tv' is
1058 detected, then an A record lookup will be made for
1059 'xyz123.tv.nod.powerdns.com'. This feature gives a way to share the
1060 newly observed domain with partners, vendors or security teams. The
1061 result of the DNS lookup will be ignored by the recursor.
1062
1063 .. _setting-new-domain-db-size:
1064
1065 ``new-domain-db-size``
1066 ----------------------
1067 .. versionadded:: 4.2.0
1068
1069 - Integer
1070 - Example: 67108864
1071
1072 The default size of the stable bloom filter used to store previously
1073 observed domains is 67108864. To change the number of cells, use this
1074 setting. For each cell, the SBF uses 1 bit of memory, and one byte of
1075 disk for the persistent file.
1076 If there are already persistent files saved to disk, this setting will
1077 have no effect unless you remove the existing files.
1078
1079 .. _setting-new-domain-history-dir:
1080
1081 ``new-domain-history-dir``
1082 --------------------------
1083 .. versionadded:: 4.2.0
1084
1085 - Path
1086
1087 This setting controls which directory is used to store the on-disk
1088 cache of previously observed domains.
1089
1090 The default depends on ``LOCALSTATEDIR`` when building the software.
1091 Usually this comes down to ``/var/lib/pdns-recursor/nod`` or ``/usr/local/var/lib/pdns-recursor/nod``).
1092
1093 The newly observed domain feature uses a stable bloom filter to store
1094 a history of previously observed domains. The data structure is
1095 synchronized to disk every 10 minutes, and is also initialized from
1096 disk on startup. This ensures that previously observed domains are
1097 preserved across recursor restarts.
1098 If you change the new-domain-db-size setting, you must remove any files
1099 from this directory.
1100
1101 .. _setting-new-domain-whitelist:
1102
1103 ``new-domain-whitelist``
1104 ------------------------
1105 .. versionadded:: 4.2.0
1106
1107 - List of Domain Names, comma separated
1108 - Example: xyz.com, abc.com
1109
1110 This setting is a list of all domains (and implicitly all subdomains)
1111 that will never be considered a new domain. For example, if the domain
1112 'xyz123.tv' is in the list, then 'foo.bar.xyz123.tv' will never be
1113 considered a new domain. One use-case for the whitelist is to never
1114 reveal details of internal subdomains via the new-domain-lookup
1115 feature.
1116
1117 .. _setting-new-domain-pb-tag:
1118
1119 ``new-domain-pb-tag``
1120 ---------------------
1121 .. versionadded:: 4.2.0
1122
1123 - String
1124 - Default: pnds-nod
1125
1126 If protobuf is configured, then this tag will be added to all protobuf response messages when
1127 a new domain is observed.
1128
1129 .. _setting-network-timeout:
1130
1131 ``network-timeout``
1132 -------------------
1133 - Integer
1134 - Default: 1500
1135
1136 Number of milliseconds to wait for a remote authoritative server to respond.
1137
1138 .. _setting-nothing-below-nxdomain:
1139
1140 ``nothing-below-nxdomain``
1141 --------------------------
1142 .. versionadded:: 4.3.0
1143
1144 - One of ``no``, ``dnssec``, ``yes``, String
1145 - Default: ``dnssec``
1146
1147 The type of :rfc:`8020` handling using cached NXDOMAIN responses.
1148 This RFC specifies that NXDOMAIN means that the DNS tree under the denied name MUST be empty.
1149 When an NXDOMAIN exists in the cache for a shorter name than the qname, no lookup is done and an NXDOMAIN is sent to the client.
1150
1151 For instance, when ``foo.example.net`` is negatively cached, any query
1152 matching ``*.foo.example.net`` will be answered with NXDOMAIN directly
1153 without consulting authoritative servers.
1154
1155 no
1156 ^^
1157 No :rfc:`8020` processing is done.
1158
1159 dnssec
1160 ^^^^^^
1161 :rfc:`8020` processing is only done using cached NXDOMAIN records that are
1162 DNSSEC validated.
1163
1164 yes
1165 ^^^
1166 :rfc:`8020` processing is done using any non-Bogus NXDOMAIN record
1167 available in the cache.
1168
1169 .. _setting-nsec3-max-iterations:
1170
1171 ``nsec3-max-iterations``
1172 ------------------------
1173 .. versionadded:: 4.1.0
1174
1175 - Integer
1176 - Default: 2500
1177
1178 Maximum number of iterations allowed for an NSEC3 record.
1179 If an answer containing an NSEC3 record with more iterations is received, its DNSSEC validation status is treated as Insecure.
1180
1181 .. _setting-packetcache-ttl:
1182
1183 ``packetcache-ttl``
1184 -------------------
1185 - Integer
1186 - Default: 3600
1187
1188 Maximum number of seconds to cache an item in the packet cache, no matter what the original TTL specified.
1189
1190 .. _setting-packetcache-servfail-ttl:
1191
1192 ``packetcache-servfail-ttl``
1193 ----------------------------
1194 - Integer
1195 - Default: 60
1196
1197 Maximum number of seconds to cache a 'server failure' answer in the packet cache.
1198
1199 .. versionchanged:: 4.0.0
1200
1201 This setting's maximum is capped to `packetcache-ttl`_.
1202 i.e. setting ``packetcache-ttl=15`` and keeping ``packetcache-servfail-ttl`` at the default will lower ``packetcache-servfail-ttl`` to ``15``.
1203
1204 .. _setting-pdns-distributes-queries:
1205
1206 ``pdns-distributes-queries``
1207 ----------------------------
1208 - Boolean
1209 - Default: yes
1210
1211 If set, PowerDNS will have only 1 thread listening on client sockets, and distribute work by itself over threads by using a hash of the query,
1212 maximizing the cache hit ratio. Starting with version 4.2.0, more than one distributing thread can be started using the `distributor-threads`_
1213 setting.
1214 Improves performance on Linux.
1215
1216 .. _setting-protobuf-use-kernel-timestamp:
1217
1218 ``protobuf-use-kernel-timestamp``
1219 ---------------------------------
1220 .. versionadded:: 4.2.0
1221
1222 - Boolean
1223 - Default: false
1224
1225 Whether to compute the latency of responses in protobuf messages using the timestamp set by the kernel when the query packet was received (when available), instead of computing it based on the moment we start processing the query.
1226
1227 .. _setting-public-suffix-list-file:
1228
1229 ``public-suffix-list-file``
1230 ---------------------------
1231 .. versionadded:: 4.2.0
1232
1233 - Path
1234 - Default: unset
1235
1236 Path to the Public Suffix List file, if any. If set, PowerDNS will try to load the Public Suffix List from this file instead of using the built-in list. The PSL is used to group the queries by relevant domain names when displaying the top queries.
1237
1238 .. _setting-qname-minimization:
1239
1240 ``qname-minimization``
1241 ----------------------
1242 .. versionadded:: 4.3.0
1243
1244 - Boolean
1245 - Default: yes
1246
1247 Enable Query Name Minimization. This implements a relaxed form of Query Name Mimimization as
1248 described in :rfc:`7816`.
1249
1250 .. _setting-query-local-address:
1251
1252 ``query-local-address``
1253 -----------------------
1254 - IPv4 Address, comma separated
1255 - Default: 0.0.0.0
1256
1257 Send out local queries from this address, or addresses, by adding multiple addresses, increased spoofing resilience is achieved.
1258
1259 .. _setting-query-local-address6:
1260
1261 ``query-local-address6``
1262 ------------------------
1263 - IPv6 addresses, comma separated
1264 - Default: unset
1265
1266 Send out local IPv6 queries from this address or addresses.
1267 Disabled by default, which also disables outgoing IPv6 support.
1268
1269 .. _setting-quiet:
1270
1271 ``quiet``
1272 ---------
1273 - Boolean
1274 - Default: yes
1275
1276 Don't log queries.
1277
1278 .. _setting-reuseport:
1279
1280 ``reuseport``
1281 -------------
1282 - Boolean
1283 - Default: no
1284
1285 If ``SO_REUSEPORT`` support is available, allows multiple processes to open a listening socket on the same port.
1286
1287 Since 4.1.0, when ``pdns-distributes-queries`` is set to false and ``reuseport`` is enabled, every thread will open a separate listening socket to let the kernel distribute the incoming queries, avoiding any thundering herd issue as well as the distributor thread being a bottleneck, thus leading to much higher performance on multi-core boxes.
1288
1289 .. _setting-rng:
1290
1291 ``rng``
1292 -------
1293
1294 - String
1295 - Default: auto
1296
1297 Specify which random number generator to use. Permissible choises are
1298 - auto - choose automatically
1299 - sodium - Use libsodium ``randombytes_uniform``
1300 - openssl - Use libcrypto ``RAND_bytes``
1301 - getrandom - Use libc getrandom, falls back to urandom if it does not really work
1302 - arc4random - Use BSD ``arc4random_uniform``
1303 - urandom - Use ``/dev/urandom``
1304 - kiss - Use simple settable deterministic RNG. **FOR TESTING PURPOSES ONLY!**
1305
1306 .. note::
1307 Not all choises are available on all systems.
1308
1309 .. _setting-root-nx-trust:
1310
1311 ``root-nx-trust``
1312 -----------------
1313 - Boolean
1314 - Default: yes
1315
1316 If set, an NXDOMAIN from the root-servers will serve as a blanket NXDOMAIN for the entire TLD the query belonged to.
1317 The effect of this is far fewer queries to the root-servers.
1318
1319 .. versionchanged:: 4.0.0
1320
1321 Default is 'yes' now, was 'no' before 4.0.0
1322
1323 .. _setting-security-poll-suffix:
1324
1325 ``security-poll-suffix``
1326 ------------------------
1327 - String
1328 - Default: secpoll.powerdns.com.
1329
1330 Domain name from which to query security update notifications.
1331 Setting this to an empty string disables secpoll.
1332
1333 .. _setting-serve-rfc1918:
1334
1335 ``serve-rfc1918``
1336 -----------------
1337 - Boolean
1338 - Default: yes
1339
1340 This makes the server authoritatively aware of: ``10.in-addr.arpa``, ``168.192.in-addr.arpa``, ``16-31.172.in-addr.arpa``, which saves load on the AS112 servers.
1341 Individual parts of these zones can still be loaded or forwarded.
1342
1343 .. _setting-server-down-max-fails:
1344
1345 ``server-down-max-fails``
1346 -------------------------
1347 - Integer
1348 - Default: 64
1349
1350 If a server has not responded in any way this many times in a row, no longer send it any queries for `server-down-throttle-time`_ seconds.
1351 Afterwards, we will try a new packet, and if that also gets no response at all, we again throttle for `server-down-throttle-time`_ seconds.
1352 Even a single response packet will drop the block.
1353
1354 .. _setting-server-down-throttle-time:
1355
1356 ``server-down-throttle-time``
1357 -----------------------------
1358 - Integer
1359 - Default: 60
1360
1361 Throttle a server that has failed to respond `server-down-max-fails`_ times for this many seconds.
1362
1363 .. _setting-server-id:
1364
1365 ``server-id``
1366 -------------
1367 - String
1368 - Default: The hostname of the server
1369
1370 The reply given by The PowerDNS recursor to a query for 'id.server' with its hostname, useful for in clusters.
1371 When a query contains the :rfc:`NSID EDNS0 Option <5001>`, this value is returned in the response as the NSID value.
1372
1373 This setting can be used to override the answer given to these queries.
1374 Set to "disabled" to disable NSID and 'id.server' answers.
1375
1376 Query example (where 192.0.2.14 is your server):
1377
1378 .. code-block:: sh
1379
1380 dig @192.0.2.14 CHAOS TXT id.server.
1381 dig @192.0.2.14 example.com IN A +nsid
1382
1383 ``setgid``, ``setuid``
1384 ----------------------
1385 - String
1386 - Default: unset
1387
1388 PowerDNS can change its user and group id after binding to its socket.
1389 Can be used for better :doc:`security <security>`.
1390
1391 .. _setting-signature-inception-skew:
1392
1393 ``signature-inception-skew``
1394 ----------------------------------
1395 .. versionadded:: 4.1.5
1396
1397 - Integer
1398 - Default: 60
1399
1400 Allow the signature inception to be off by this number of seconds. Negative values are not allowed.
1401
1402 .. versionchanged:: 4.2.0
1403
1404 Default is now 60, was 0 before.
1405
1406 .. _setting-single-socket:
1407
1408 ``single-socket``
1409 -----------------
1410 - Boolean
1411 - Default: no
1412
1413 Use only a single socket for outgoing queries.
1414
1415 .. _setting-snmp-agent:
1416
1417 ``snmp-agent``
1418 --------------
1419 .. versionadded:: 4.1.0
1420
1421 - Boolean
1422 - Default: no
1423
1424 If set to true and PowerDNS has been compiled with SNMP support, it will register as an SNMP agent to provide statistics and be able to send traps.
1425
1426 .. _setting-snmp-master-socket:
1427
1428 ``snmp-master-socket``
1429 ----------------------
1430 .. versionadded:: 4.1.0
1431
1432 - String
1433 - Default: empty
1434
1435 If not empty and ``snmp-agent`` is set to true, indicates how PowerDNS should contact the SNMP master to register as an SNMP agent.
1436
1437 .. _setting-socket-dir:
1438
1439 ``socket-dir``
1440 --------------
1441 - Path
1442
1443 Where to store the control socket and pidfile.
1444 The default depends on ``LOCALSTATEDIR`` or the ``--with-socketdir`` setting when building (usually ``/var/run`` or ``/run``).
1445
1446 When using `chroot`_ the default becomes to ``/``.
1447
1448 ``socket-owner``, ``socket-group``, ``socket-mode``
1449 ---------------------------------------------------
1450 Owner, group and mode of the controlsocket.
1451 Owner and group can be specified by name, mode is in octal.
1452
1453 .. _setting-spoof-nearmiss-max:
1454
1455 ``spoof-nearmiss-max``
1456 ----------------------
1457 - Integer
1458 - Default: 20
1459
1460 If set to non-zero, PowerDNS will assume it is being spoofed after seeing this many answers with the wrong id.
1461
1462 .. _setting-stack-size:
1463
1464 ``stack-size``
1465 --------------
1466 - Integer
1467 - Default: 200000
1468
1469 Size of the stack per thread.
1470
1471 .. _setting-statistics-interval:
1472
1473 ``statistics-interval``
1474 -----------------------
1475 .. versionadded:: 4.1.0
1476
1477 - Integer
1478 - Default: 1800
1479
1480 Interval between logging statistical summary on recursor performance.
1481 Use 0 to disable.
1482
1483 .. _setting-stats-api-blacklist:
1484
1485 ``stats-api-blacklist``
1486 -----------------------
1487 .. versionadded:: 4.2.0
1488
1489 - String
1490 - Default: "cache-bytes, packetcache-bytes, special-memory-usage, ecs-v4-response-bits-*, ecs-v6-response-bits-*"
1491
1492 A list of comma-separated statistic names, that are disabled when retrieving the complete list of statistics via the API for performance reasons.
1493 These statistics can still be retrieved individually by specifically asking for it.
1494
1495 .. _setting-stats-carbon-blacklist:
1496
1497 ``stats-carbon-blacklist``
1498 --------------------------
1499 .. versionadded:: 4.2.0
1500
1501 - String
1502 - Default: "cache-bytes, packetcache-bytes, special-memory-usage, ecs-v4-response-bits-*, ecs-v6-response-bits-*"
1503
1504 A list of comma-separated statistic names, that are prevented from being exported via carbon for performance reasons.
1505
1506 .. _setting-stats-rec-control-blacklist:
1507
1508 ``stats-rec-control-blacklist``
1509 -------------------------------
1510 .. versionadded:: 4.2.0
1511
1512 - String
1513 - Default: "cache-bytes, packetcache-bytes, special-memory-usage, ecs-v4-response-bits-*, ecs-v6-response-bits-*"
1514
1515 A list of comma-separated statistic names, that are disabled when retrieving the complete list of statistics via `rec_control get-all`, for performance reasons.
1516 These statistics can still be retrieved individually.
1517
1518 .. _setting-stats-ringbuffer-entries:
1519
1520 ``stats-ringbuffer-entries``
1521 ----------------------------
1522 - Integer
1523 - Default: 10000
1524
1525 Number of entries in the remotes ringbuffer, which keeps statistics on who is querying your server.
1526 Can be read out using ``rec_control top-remotes``.
1527
1528 .. _setting-stats-snmp-blacklist:
1529
1530 ``stats-snmp-blacklist``
1531 ------------------------
1532 .. versionadded:: 4.2.0
1533
1534 - String
1535 - Default: "cache-bytes, packetcache-bytes, special-memory-usage, ecs-v4-response-bits-*, ecs-v6-response-bits-*"
1536
1537 A list of comma-separated statistic names, that are prevented from being exported via SNMP, for performance reasons.
1538
1539 .. _setting-tcp-fast-open:
1540
1541 ``tcp-fast-open``
1542 -----------------
1543 .. versionadded:: 4.1.0
1544
1545 - Integer
1546 - Default: 0 (Disabled)
1547
1548 Enable TCP Fast Open support, if available, on the listening sockets.
1549 The numerical value supplied is used as the queue size, 0 meaning disabled.
1550
1551 .. _setting-threads:
1552
1553 ``threads``
1554 -----------
1555 - Integer
1556 - Default: 2
1557
1558 Spawn this number of threads on startup.
1559
1560 .. _setting-trace:
1561
1562 ``trace``
1563 ---------
1564 - Boolean
1565 - Default: no
1566
1567 If turned on, output impressive heaps of logging.
1568 May destroy performance under load.
1569
1570 .. _setting-udp-source-port-min:
1571
1572 ``udp-source-port-min``
1573 -----------------------
1574 .. versionadded:: 4.2.0
1575
1576 - Integer
1577 - Default: 1024
1578
1579 This option sets the low limit of UDP port number to bind on.
1580
1581 In combination with `udp-source-port-max`_ it configures the UDP
1582 port range to use. Port numbers are randomized within this range on
1583 initialization, and exceptions can be configured with `udp-source-port-avoid`_
1584
1585 .. _setting-udp-source-port-max:
1586
1587 ``udp-source-port-max``
1588 -----------------------
1589 .. versionadded:: 4.2.0
1590
1591 - Integer
1592 - Default: 65535
1593
1594 This option sets the maximum limit of UDP port number to bind on.
1595
1596 See `udp-source-port-min`_.
1597
1598 .. _setting-udp-source-port-avoid:
1599
1600 ``udp-source-port-avoid``
1601 -------------------------
1602 .. versionadded:: 4.2.0
1603
1604 - String
1605 - Default: 11211
1606
1607 A list of comma-separated UDP port numbers to avoid when binding.
1608 Ex: `5300,11211`
1609
1610 See `udp-source-port-min`_.
1611
1612 .. _setting-udp-truncation-threshold:
1613
1614 ``udp-truncation-threshold``
1615 ----------------------------
1616 .. versionchanged:: 4.2.0
1617 Before 4.2.0, the default was 1680
1618
1619 - Integer
1620 - Default: 1232
1621
1622 EDNS0 allows for large UDP response datagrams, which can potentially raise performance.
1623 Large responses however also have downsides in terms of reflection attacks.
1624 This setting limits the accepted size.
1625 Maximum value is 65535, but values above 4096 should probably not be attempted.
1626
1627 To know why 1232, see the note at :ref:`setting-edns-outgoing-bufsize`.
1628
1629 .. _setting-unique-response-tracking:
1630
1631 ``unique-response-tracking``
1632 ----------------------------
1633 .. versionadded:: 4.2.0
1634
1635 - Boolean
1636 - Default: no (disabled)
1637
1638 Whether to track unique DNS responses, i.e. never seen before combinations
1639 of the triplet (query name, query type, RR[rrname, rrtype, rrdata]).
1640 This can be useful for tracking potentially suspicious domains and
1641 behaviour, e.g. DNS fast-flux.
1642 If protobuf is enabled and configured, then the Protobuf Response message
1643 will contain a flag with udr set to true for each RR that is considered
1644 unique, i.e. never seen before.
1645 This feature uses a probabilistic data structure (stable bloom filter) to
1646 track unique responses, which can have false positives as well as false
1647 negatives, thus it is a best-effort feature. Increasing the number of cells
1648 in the SBF using the unique-response-db-size setting can reduce FPs and FNs.
1649
1650 .. _setting-unique-response-log:
1651
1652 ``unique-response-log``
1653 -----------------------
1654 .. versionadded:: 4.2.0
1655
1656 - Boolean
1657 - Default: no (disabled)
1658
1659 Whether to log when a unique response is detected. The log line
1660 looks something like:
1661
1662 Oct 24 12:11:27 Unique response observed: qname=foo.com qtype=A rrtype=AAAA rrname=foo.com rrcontent=1.2.3.4
1663
1664 .. _setting-unique-response-db-size:
1665
1666 ``unique-response-db-size``
1667 ---------------------------
1668 .. versionadded:: 4.2.0
1669
1670 - Integer
1671 - Example: 67108864
1672
1673 The default size of the stable bloom filter used to store previously
1674 observed responses is 67108864. To change the number of cells, use this
1675 setting. For each cell, the SBF uses 1 bit of memory, and one byte of
1676 disk for the persistent file.
1677 If there are already persistent files saved to disk, this setting will
1678 have no effect unless you remove the existing files.
1679
1680 .. _setting-unique-response-history-dir:
1681
1682 ``unique-response-history-dir``
1683 -------------------------------
1684 .. versionadded:: 4.2.0
1685
1686 - Path
1687
1688 This setting controls which directory is used to store the on-disk
1689 cache of previously observed responses.
1690
1691 The default depends on ``LOCALSTATEDIR`` when building the software.
1692 Usually this comes down to ``/var/lib/pdns-recursor/udr`` or ``/usr/local/var/lib/pdns-recursor/udr``).
1693
1694 The newly observed domain feature uses a stable bloom filter to store
1695 a history of previously observed responses. The data structure is
1696 synchronized to disk every 10 minutes, and is also initialized from
1697 disk on startup. This ensures that previously observed responses are
1698 preserved across recursor restarts. If you change the
1699 unique-response-db-size, you must remove any files from this directory.
1700
1701 .. _setting-unique-response-pb-tag:
1702
1703 ``unique-response-pb-tag``
1704 --------------------------
1705 .. versionadded:: 4.2.0
1706
1707 - String
1708 - Default: pnds-udr
1709
1710 If protobuf is configured, then this tag will be added to all protobuf response messages when
1711 a unique DNS response is observed.
1712
1713 .. _setting-use-incoming-edns-subnet:
1714
1715 ``use-incoming-edns-subnet``
1716 ----------------------------
1717 - Boolean
1718 - Default: no
1719
1720 Whether to process and pass along a received EDNS Client Subnet to authoritative servers.
1721 The ECS information will only be sent for netmasks and domains listed in `edns-subnet-whitelist`_ and will be truncated if the received scope exceeds `ecs-ipv4-bits`_ for IPv4 or `ecs-ipv6-bits`_ for IPv6.
1722
1723 .. _setting-version:
1724
1725 ``version``
1726 -----------
1727 Print version of this binary. Useful for checking which version of the PowerDNS recursor is installed on a system.
1728
1729 .. _setting-version-string:
1730
1731 ``version-string``
1732 ------------------
1733 - String
1734 - Default: PowerDNS Recursor version number
1735
1736 By default, PowerDNS replies to the 'version.bind' query with its version number.
1737 Security conscious users may wish to override the reply PowerDNS issues.
1738
1739 .. _setting-webserver:
1740
1741 ``webserver``
1742 -------------
1743 - Boolean
1744 - Default: no
1745
1746 Start the webserver (for REST API).
1747
1748 .. _setting-webserver-address:
1749
1750 ``webserver-address``
1751 ---------------------
1752 - IP Address
1753 - Default: 127.0.0.1
1754
1755 IP address for the webserver to listen on.
1756
1757 .. _setting-webserver-allow-from:
1758
1759 ``webserver-allow-from``
1760 ------------------------
1761 - IP addresses, comma separated
1762 - Default: 127.0.0.1,::1
1763
1764 .. versionchanged:: 4.1.0
1765
1766 Default is now 127.0.0.1,::1, was 0.0.0.0,::/0 before.
1767
1768 These subnets are allowed to access the webserver.
1769
1770 .. _setting-webserver-loglevel:
1771
1772 ``webserver-loglevel``
1773 ----------------------
1774 .. versionadded:: 4.2.0
1775
1776 - String, one of "none", "normal", "detailed"
1777
1778 The amount of logging the webserver must do. "none" means no useful webserver information will be logged.
1779 When set to "normal", the webserver will log a line per request that should be familiar::
1780
1781 [webserver] e235780e-a5cf-415e-9326-9d33383e739e 127.0.0.1:55376 "GET /api/v1/servers/localhost/bla HTTP/1.1" 404 196
1782
1783 When set to "detailed", all information about the request and response are logged::
1784
1785 [webserver] e235780e-a5cf-415e-9326-9d33383e739e Request Details:
1786 [webserver] e235780e-a5cf-415e-9326-9d33383e739e Headers:
1787 [webserver] e235780e-a5cf-415e-9326-9d33383e739e accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
1788 [webserver] e235780e-a5cf-415e-9326-9d33383e739e accept-encoding: gzip, deflate
1789 [webserver] e235780e-a5cf-415e-9326-9d33383e739e accept-language: en-US,en;q=0.5
1790 [webserver] e235780e-a5cf-415e-9326-9d33383e739e connection: keep-alive
1791 [webserver] e235780e-a5cf-415e-9326-9d33383e739e dnt: 1
1792 [webserver] e235780e-a5cf-415e-9326-9d33383e739e host: 127.0.0.1:8081
1793 [webserver] e235780e-a5cf-415e-9326-9d33383e739e upgrade-insecure-requests: 1
1794 [webserver] e235780e-a5cf-415e-9326-9d33383e739e user-agent: Mozilla/5.0 (X11; Linux x86_64; rv:64.0) Gecko/20100101 Firefox/64.0
1795 [webserver] e235780e-a5cf-415e-9326-9d33383e739e No body
1796 [webserver] e235780e-a5cf-415e-9326-9d33383e739e Response details:
1797 [webserver] e235780e-a5cf-415e-9326-9d33383e739e Headers:
1798 [webserver] e235780e-a5cf-415e-9326-9d33383e739e Connection: close
1799 [webserver] e235780e-a5cf-415e-9326-9d33383e739e Content-Length: 49
1800 [webserver] e235780e-a5cf-415e-9326-9d33383e739e Content-Type: text/html; charset=utf-8
1801 [webserver] e235780e-a5cf-415e-9326-9d33383e739e Server: PowerDNS/0.0.15896.0.gaba8bab3ab
1802 [webserver] e235780e-a5cf-415e-9326-9d33383e739e Full body:
1803 [webserver] e235780e-a5cf-415e-9326-9d33383e739e <!html><title>Not Found</title><h1>Not Found</h1>
1804 [webserver] e235780e-a5cf-415e-9326-9d33383e739e 127.0.0.1:55376 "GET /api/v1/servers/localhost/bla HTTP/1.1" 404 196
1805
1806 The value between the hooks is a UUID that is generated for each request. This can be used to find all lines related to a single request.
1807
1808 .. note::
1809 The webserver logs these line on the NOTICE level. The :ref:`settings-loglevel` seting must be 5 or higher for these lines to end up in the log.
1810
1811 .. _setting-webserver-password:
1812
1813 ``webserver-password``
1814 ----------------------
1815 - String
1816 - Default: unset
1817
1818 Password required to access the webserver.
1819
1820 .. _setting-webserver-port:
1821
1822 ``webserver-port``
1823 ------------------
1824 - Integer
1825 - Default: 8082
1826
1827 TCP port where the webserver should listen on.
1828
1829 .. _setting-write-pid:
1830
1831 ``write-pid``
1832 -------------
1833 - Boolean
1834 - Default: yes
1835
1836 If a PID file should be written to `socket-dir`_
1837
1838 .. _setting-xpf-allow-from:
1839
1840 ``xpf-allow-from``
1841 ------------------
1842 .. versionadded:: 4.2.0
1843
1844 - IP ranges, separated by commas
1845 - Default: empty
1846
1847 .. note::
1848 This is an experimental implementation of `draft-bellis-dnsop-xpf <https://datatracker.ietf.org/doc/draft-bellis-dnsop-xpf/>`_.
1849
1850 The server will trust XPF records found in queries sent from those netmasks (both IPv4 and IPv6),
1851 and will adjust queries' source and destination accordingly. This is especially useful when the recursor
1852 is placed behind a proxy like `dnsdist <https://dnsdist.org>`_.
1853 Note that the :ref:`setting-allow-from` setting is still applied to the original source address, and thus access restriction
1854 should be done on the proxy.
1855
1856 .. _setting-xpf-rr-code:
1857
1858 ``xpf-rr-code``
1859 ---------------
1860 .. versionadded:: 4.2.0
1861
1862 - Integer
1863 - Default: 0
1864
1865 .. note::
1866 This is an experimental implementation of `draft-bellis-dnsop-xpf <https://datatracker.ietf.org/doc/draft-bellis-dnsop-xpf/>`_.
1867
1868 This option sets the resource record code to use for XPF records, as long as an official code has not been assigned to it.
1869 0 means that XPF is disabled.