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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:: 4.1.4
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-mthreads:
865
866 ``max-mthreads``
867 ----------------
868 - Integer
869 - Default: 2048
870
871 Maximum number of simultaneous MTasker threads.
872
873 .. _setting-max-packetcache-entries:
874
875 ``max-packetcache-entries``
876 ---------------------------
877 - Integer
878 - Default: 500000
879
880 Maximum number of Packet Cache entries.
881 1 million per thread will generally suffice for most installations.
882
883 .. _setting-max-qperq:
884
885 ``max-qperq``
886 -------------
887 - Integer
888 - Default: 50
889
890 The maximum number of outgoing queries that will be sent out during the resolution of a single client query.
891 This is used to limit endlessly chasing CNAME redirections.
892
893 .. _setting-max-negative-ttl:
894
895 ``max-negative-ttl``
896 --------------------
897 - Integer
898 - Default: 3600
899
900 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.
901 In practice, caches can become saturated with hundreds of thousands of hosts which are tried only once.
902 This setting, which defaults to 3600 seconds, puts a maximum on the amount of time negative entries are cached.
903
904 .. _setting-max-recursion-depth:
905
906 ``max-recursion-depth``
907 -----------------------
908 - Integer
909 - Default: 40
910
911 Total maximum number of internal recursion calls the server may use to answer a single query.
912 0 means unlimited.
913 The value of `stack-size`_ should be increased together with this one to prevent the stack from overflowing.
914
915 .. versionchanged:: 4.1.0
916
917 Before 4.1.0, this settings was unlimited.
918
919 .. _setting-max-tcp-clients:
920
921 ``max-tcp-clients``
922 -------------------
923 - Integer
924 - Default: 128
925
926 Maximum number of simultaneous incoming TCP connections allowed.
927
928 .. _setting-max-tcp-per-client:
929
930 ``max-tcp-per-client``
931 ----------------------
932 - Integer
933 - Default: 0 (unlimited)
934
935 Maximum number of simultaneous incoming TCP connections allowed per client (remote IP address).
936
937 .. _setting-max-tcp-queries-per-connection:
938
939 ``max-tcp-queries-per-connection``
940 ----------------------------------
941 .. versionadded:: 4.1.0
942
943 - Integer
944 - Default: 0 (unlimited)
945
946 Maximum number of DNS queries in a TCP connection.
947
948 .. _setting-max-total-msec:
949
950 ``max-total-msec``
951 ------------------
952 - Integer
953 - Default: 7000
954
955 Total maximum number of milliseconds of wallclock time the server may use to answer a single query.
956
957 .. _setting-max-udp-queries-per-round:
958
959 ``max-udp-queries-per-round``
960 ----------------------------------
961 .. versionadded:: 4.1.4
962
963 - Integer
964 - Default: 10000
965
966 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
967 neglect scheduling new ``mthreads``, handling responses from authoritative servers or responding to :doc:`rec_control <manpages/rec_control.1>`
968 requests.
969 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
970 returning back to normal processing and handling other events.
971
972 .. _setting-minimum-ttl-override:
973
974 ``minimum-ttl-override``
975 ------------------------
976 - Integer
977 - Default: 0 (disabled)
978
979 This setting artificially raises all TTLs to be at least this long.
980 While this is a gross hack, and violates RFCs, under conditions of DoS, it may enable you to continue serving your customers.
981 Can be set at runtime using ``rec_control set-minimum-ttl 3600``.
982
983 .. _setting-new-domain-tracking:
984
985 ``new-domain-tracking``
986 -----------------------
987 .. versionadded:: 4.2.0
988
989 - Boolean
990 - Default: no (disabled)
991
992 Whether to track newly observed domains, i.e. never seen before. This
993 is a probablistic algorithm, using a stable bloom filter to store
994 records of previously seen domains. When enabled for the first time,
995 all domains will appear to be newly observed, so the feature is best
996 left enabled for e.g. a week or longer before using the results. Note
997 that this feature is optional and must be enabled at compile-time,
998 thus it may not be available in all pre-built packages.
999 If protobuf is enabled and configured, then the newly observed domain
1000 status will appear as a flag in Response messages.
1001
1002 .. _setting-new-domain-log:
1003
1004 ``new-domain-log``
1005 ------------------
1006 .. versionadded:: 4.2.0
1007
1008 - Boolean
1009 - Default: yes (enabled)
1010
1011 If a newly observed domain is detected, log that domain in the
1012 recursor log file. The log line looks something like::
1013
1014 Jul 18 11:31:25 Newly observed domain nod=sdfoijdfio.com
1015
1016 .. _setting-new-domain-lookup:
1017
1018 ``new-domain-lookup``
1019 ---------------------
1020 .. versionadded:: 4.2.0
1021
1022 - Domain Name
1023 - Example: nod.powerdns.com
1024
1025 If a domain is specified, then each time a newly observed domain is
1026 detected, the recursor will perform an A record lookup of "<newly
1027 observed domain>.<lookup domain>". For example if 'new-domain-lookup'
1028 is configured as 'nod.powerdns.com', and a new domain 'xyz123.tv' is
1029 detected, then an A record lookup will be made for
1030 'xyz123.tv.nod.powerdns.com'. This feature gives a way to share the
1031 newly observed domain with partners, vendors or security teams. The
1032 result of the DNS lookup will be ignored by the recursor.
1033
1034 .. _setting-new-domain-db-size:
1035
1036 ``new-domain-db-size``
1037 ----------------------
1038 .. versionadded:: 4.2.0
1039
1040 - Integer
1041 - Example: 67108864
1042
1043 The default size of the stable bloom filter used to store previously
1044 observed domains is 67108864. To change the number of cells, use this
1045 setting. For each cell, the SBF uses 1 bit of memory, and one byte of
1046 disk for the persistent file.
1047 If there are already persistent files saved to disk, this setting will
1048 have no effect unless you remove the existing files.
1049
1050 .. _setting-new-domain-history-dir:
1051
1052 ``new-domain-history-dir``
1053 --------------------------
1054 .. versionadded:: 4.2.0
1055
1056 - Path
1057
1058 This setting controls which directory is used to store the on-disk
1059 cache of previously observed domains.
1060
1061 The default depends on ``LOCALSTATEDIR`` when building the software.
1062 Usually this comes down to ``/var/lib/pdns-recursor/nod`` or ``/usr/local/var/lib/pdns-recursor/nod``).
1063
1064 The newly observed domain feature uses a stable bloom filter to store
1065 a history of previously observed domains. The data structure is
1066 synchronized to disk every 10 minutes, and is also initialized from
1067 disk on startup. This ensures that previously observed domains are
1068 preserved across recursor restarts.
1069 If you change the new-domain-db-size setting, you must remove any files
1070 from this directory.
1071
1072 .. _setting-new-domain-whitelist:
1073
1074 ``new-domain-whitelist``
1075 ------------------------
1076 .. versionadded:: 4.2.0
1077
1078 - List of Domain Names, comma separated
1079 - Example: xyz.com, abc.com
1080
1081 This setting is a list of all domains (and implicitly all subdomains)
1082 that will never be considered a new domain. For example, if the domain
1083 'xyz123.tv' is in the list, then 'foo.bar.xyz123.tv' will never be
1084 considered a new domain. One use-case for the whitelist is to never
1085 reveal details of internal subdomains via the new-domain-lookup
1086 feature.
1087
1088 .. _setting-new-domain-pb-tag:
1089
1090 ``new-domain-pb-tag``
1091 ---------------------
1092 .. versionadded:: 4.2.0
1093
1094 - String
1095 - Default: pnds-nod
1096
1097 If protobuf is configured, then this tag will be added to all protobuf response messages when
1098 a new domain is observed.
1099
1100 .. _setting-network-timeout:
1101
1102 ``network-timeout``
1103 -------------------
1104 - Integer
1105 - Default: 1500
1106
1107 Number of milliseconds to wait for a remote authoritative server to respond.
1108
1109 .. _setting-nsec3-max-iterations:
1110
1111 ``nsec3-max-iterations``
1112 ------------------------
1113 .. versionadded:: 4.1.0
1114
1115 - Integer
1116 - Default: 2500
1117
1118 Maximum number of iterations allowed for an NSEC3 record.
1119 If an answer containing an NSEC3 record with more iterations is received, its DNSSEC validation status is treated as Insecure.
1120
1121 .. _setting-packetcache-ttl:
1122
1123 ``packetcache-ttl``
1124 -------------------
1125 - Integer
1126 - Default: 3600
1127
1128 Maximum number of seconds to cache an item in the packet cache, no matter what the original TTL specified.
1129
1130 .. _setting-packetcache-servfail-ttl:
1131
1132 ``packetcache-servfail-ttl``
1133 ----------------------------
1134 - Integer
1135 - Default: 60
1136
1137 Maximum number of seconds to cache a 'server failure' answer in the packet cache.
1138
1139 .. versionchanged:: 4.0.0
1140
1141 This setting's maximum is capped to `packetcache-ttl`_.
1142 i.e. setting ``packetcache-ttl=15`` and keeping ``packetcache-servfail-ttl`` at the default will lower ``packetcache-servfail-ttl`` to ``15``.
1143
1144 .. _setting-pdns-distributes-queries:
1145
1146 ``pdns-distributes-queries``
1147 ----------------------------
1148 - Boolean
1149 - Default: yes
1150
1151 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,
1152 maximizing the cache hit ratio. Starting with version 4.2.0, more than one distributing thread can be started using the `distributor-threads`_
1153 setting.
1154 Improves performance on Linux.
1155
1156 .. _settting-protobuf-use-kernel-timestamp:
1157
1158 ``protobuf-use-kernel-timestamp``
1159 ---------------------------------
1160 .. versionadded:: 4.2.0
1161
1162 - Boolean
1163 - Default: false
1164
1165 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.
1166
1167 .. _settting-public-suffix-list-file:
1168
1169 ``public-suffix-list-file``
1170 ---------------------------
1171 .. versionadded:: 4.2.0
1172
1173 - Path
1174 - Default: unset
1175
1176 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.
1177
1178 .. _setting-qname-minimization:
1179
1180 ``qname-minimization``
1181 ----------------------
1182 .. versionadded:: 4.3.0
1183
1184 - Boolean
1185 - Default: no
1186
1187 Enable Query Name Minimization. This is a experimental feature, implementing a relaxed form of Query Name Mimimization as
1188 described in :rfc:`7816`.
1189
1190 .. _setting-query-local-address:
1191
1192 ``query-local-address``
1193 -----------------------
1194 - IPv4 Address, comma separated
1195 - Default: 0.0.0.0
1196
1197 Send out local queries from this address, or addresses, by adding multiple addresses, increased spoofing resilience is achieved.
1198
1199 .. _setting-query-local-address6:
1200
1201 ``query-local-address6``
1202 ------------------------
1203 - IPv6 addresses, comma separated
1204 - Default: unset
1205
1206 Send out local IPv6 queries from this address or addresses.
1207 Disabled by default, which also disables outgoing IPv6 support.
1208
1209 .. _setting-quiet:
1210
1211 ``quiet``
1212 ---------
1213 - Boolean
1214 - Default: yes
1215
1216 Don't log queries.
1217
1218 .. _setting-reuseport:
1219
1220 ``reuseport``
1221 -------------
1222 - Boolean
1223 - Default: no
1224
1225 If ``SO_REUSEPORT`` support is available, allows multiple processes to open a listening socket on the same port.
1226
1227 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.
1228
1229 .. _setting-rng:
1230
1231 ``rng``
1232 -------
1233
1234 - String
1235 - Default: auto
1236
1237 Specify which random number generator to use. Permissible choises are
1238 - auto - choose automatically
1239 - sodium - Use libsodium ``randombytes_uniform``
1240 - openssl - Use libcrypto ``RAND_bytes``
1241 - getrandom - Use libc getrandom, falls back to urandom if it does not really work
1242 - arc4random - Use BSD ``arc4random_uniform``
1243 - urandom - Use ``/dev/urandom``
1244 - kiss - Use simple settable deterministic RNG. **FOR TESTING PURPOSES ONLY!**
1245
1246 .. note::
1247 Not all choises are available on all systems.
1248
1249 .. _setting-root-nx-trust:
1250
1251 ``root-nx-trust``
1252 -----------------
1253 - Boolean
1254 - Default: yes
1255
1256 If set, an NXDOMAIN from the root-servers will serve as a blanket NXDOMAIN for the entire TLD the query belonged to.
1257 The effect of this is far fewer queries to the root-servers.
1258
1259 .. versionchanged:: 4.0.0
1260
1261 Default is 'yes' now, was 'no' before 4.0.0
1262
1263 .. _setting-security-poll-suffix:
1264
1265 ``security-poll-suffix``
1266 ------------------------
1267 - String
1268 - Default: secpoll.powerdns.com.
1269
1270 Domain name from which to query security update notifications.
1271 Setting this to an empty string disables secpoll.
1272
1273 .. _setting-serve-rfc1918:
1274
1275 ``serve-rfc1918``
1276 -----------------
1277 - Boolean
1278 - Default: yes
1279
1280 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.
1281 Individual parts of these zones can still be loaded or forwarded.
1282
1283 .. _setting-server-down-max-fails:
1284
1285 ``server-down-max-fails``
1286 -------------------------
1287 - Integer
1288 - Default: 64
1289
1290 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.
1291 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.
1292 Even a single response packet will drop the block.
1293
1294 .. _setting-server-down-throttle-time:
1295
1296 ``server-down-throttle-time``
1297 -----------------------------
1298 - Integer
1299 - Default: 60
1300
1301 Throttle a server that has failed to respond `server-down-max-fails`_ times for this many seconds.
1302
1303 .. _setting-server-id:
1304
1305 ``server-id``
1306 -------------
1307 - String
1308 - Default: The hostname of the server
1309
1310 The reply given by The PowerDNS recursor to a query for 'id.server' with its hostname, useful for in clusters.
1311 When a query contains the :rfc:`NSID EDNS0 Option <5001>`, this value is returned in the response as the NSID value.
1312
1313 This setting can be used to override the answer given to these queries.
1314 Set to "disabled" to disable NSID and 'id.server' answers.
1315
1316 Query example (where 192.0.2.14 is your server):
1317
1318 .. code-block:: sh
1319
1320 dig @192.0.2.14 CHAOS TXT id.server.
1321 dig @192.0.2.14 example.com IN A +nsid
1322
1323 ``setgid``, ``setuid``
1324 ----------------------
1325 - String
1326 - Default: unset
1327
1328 PowerDNS can change its user and group id after binding to its socket.
1329 Can be used for better :doc:`security <security>`.
1330
1331 .. _setting-signature-inception-skew:
1332
1333 ``signature-inception-skew``
1334 ----------------------------------
1335 .. versionadded:: 4.1.5
1336
1337 - Integer
1338 - Default: 60
1339
1340 Allow the signature inception to be off by this number of seconds. Negative values are not allowed.
1341
1342 .. versionchanged:: 4.2.0
1343
1344 Default is now 60, was 0 before.
1345
1346 .. _setting-single-socket:
1347
1348 ``single-socket``
1349 -----------------
1350 - Boolean
1351 - Default: no
1352
1353 Use only a single socket for outgoing queries.
1354
1355 .. _setting-snmp-agent:
1356
1357 ``snmp-agent``
1358 --------------
1359 .. versionadded:: 4.1.0
1360
1361 - Boolean
1362 - Default: no
1363
1364 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.
1365
1366 .. _setting-snmp-master-socket:
1367
1368 ``snmp-master-socket``
1369 ----------------------
1370 .. versionadded:: 4.1.0
1371
1372 - String
1373 - Default: empty
1374
1375 If not empty and ``snmp-agent`` is set to true, indicates how PowerDNS should contact the SNMP master to register as an SNMP agent.
1376
1377 .. _setting-socket-dir:
1378
1379 ``socket-dir``
1380 --------------
1381 - Path
1382
1383 Where to store the control socket and pidfile.
1384 The default depends on ``LOCALSTATEDIR`` or the ``--with-socketdir`` setting when building (usually ``/var/run`` or ``/run``).
1385
1386 When using `chroot`_ the default becomes to ``/``.
1387
1388 ``socket-owner``, ``socket-group``, ``socket-mode``
1389 ---------------------------------------------------
1390 Owner, group and mode of the controlsocket.
1391 Owner and group can be specified by name, mode is in octal.
1392
1393 .. _setting-spoof-nearmiss-max:
1394
1395 ``spoof-nearmiss-max``
1396 ----------------------
1397 - Integer
1398 - Default: 20
1399
1400 If set to non-zero, PowerDNS will assume it is being spoofed after seeing this many answers with the wrong id.
1401
1402 .. _setting-stack-size:
1403
1404 ``stack-size``
1405 --------------
1406 - Integer
1407 - Default: 200000
1408
1409 Size of the stack per thread.
1410
1411 .. _setting-statistics-interval:
1412
1413 ``statistics-interval``
1414 -----------------------
1415 .. versionadded:: 4.1.0
1416
1417 - Integer
1418 - Default: 1800
1419
1420 Interval between logging statistical summary on recursor performance.
1421 Use 0 to disable.
1422
1423 .. _setting-stats-api-blacklist:
1424
1425 ``stats-api-blacklist``
1426 -----------------------
1427 .. versionadded:: 4.2.0
1428
1429 - String
1430 - Default: "cache-bytes, packetcache-bytes, special-memory-usage, ecs-v4-response-bits-*, ecs-v6-response-bits-*"
1431
1432 A list of comma-separated statistic names, that are disabled when retrieving the complete list of statistics via the API for performance reasons.
1433 These statistics can still be retrieved individually by specifically asking for it.
1434
1435 .. _setting-stats-carbon-blacklist:
1436
1437 ``stats-carbon-blacklist``
1438 --------------------------
1439 .. versionadded:: 4.2.0
1440
1441 - String
1442 - Default: "cache-bytes, packetcache-bytes, special-memory-usage, ecs-v4-response-bits-*, ecs-v6-response-bits-*"
1443
1444 A list of comma-separated statistic names, that are prevented from being exported via carbon for performance reasons.
1445
1446 .. _setting-stats-rec-control-blacklist:
1447
1448 ``stats-rec-control-blacklist``
1449 -------------------------------
1450 .. versionadded:: 4.2.0
1451
1452 - String
1453 - Default: "cache-bytes, packetcache-bytes, special-memory-usage, ecs-v4-response-bits-*, ecs-v6-response-bits-*"
1454
1455 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.
1456 These statistics can still be retrieved individually.
1457
1458 .. _setting-stats-ringbuffer-entries:
1459
1460 ``stats-ringbuffer-entries``
1461 ----------------------------
1462 - Integer
1463 - Default: 10000
1464
1465 Number of entries in the remotes ringbuffer, which keeps statistics on who is querying your server.
1466 Can be read out using ``rec_control top-remotes``.
1467
1468 .. _setting-stats-snmp-blacklist:
1469
1470 ``stats-snmp-blacklist``
1471 ------------------------
1472 .. versionadded:: 4.2.0
1473
1474 - String
1475 - Default: "cache-bytes, packetcache-bytes, special-memory-usage, ecs-v4-response-bits-*, ecs-v6-response-bits-*"
1476
1477 A list of comma-separated statistic names, that are prevented from being exported via SNMP, for performance reasons.
1478
1479 .. _setting-tcp-fast-open:
1480
1481 ``tcp-fast-open``
1482 -----------------
1483 .. versionadded:: 4.1.0
1484
1485 - Integer
1486 - Default: 0 (Disabled)
1487
1488 Enable TCP Fast Open support, if available, on the listening sockets.
1489 The numerical value supplied is used as the queue size, 0 meaning disabled.
1490
1491 .. _setting-threads:
1492
1493 ``threads``
1494 -----------
1495 - Integer
1496 - Default: 2
1497
1498 Spawn this number of threads on startup.
1499
1500 .. _setting-trace:
1501
1502 ``trace``
1503 ---------
1504 - Boolean
1505 - Default: no
1506
1507 If turned on, output impressive heaps of logging.
1508 May destroy performance under load.
1509
1510 .. _setting-udp-source-port-min:
1511
1512 ``udp-source-port-min``
1513 -----------------------
1514 .. versionadded:: 4.2.0
1515
1516 - Integer
1517 - Default: 1024
1518
1519 This option sets the low limit of UDP port number to bind on.
1520
1521 In combination with `udp-source-port-max`_ it configures the UDP
1522 port range to use. Port numbers are randomized within this range on
1523 initialization, and exceptions can be configured with `udp-source-port-avoid`_
1524
1525 .. _setting-udp-source-port-max:
1526
1527 ``udp-source-port-max``
1528 -----------------------
1529 .. versionadded:: 4.2.0
1530
1531 - Integer
1532 - Default: 65535
1533
1534 This option sets the maximum limit of UDP port number to bind on.
1535
1536 See `udp-source-port-min`_.
1537
1538 .. _setting-udp-source-port-avoid:
1539
1540 ``udp-source-port-avoid``
1541 -------------------------
1542 .. versionadded:: 4.2.0
1543
1544 - String
1545 - Default: 11211
1546
1547 A list of comma-separated UDP port numbers to avoid when binding.
1548 Ex: `5300,11211`
1549
1550 See `udp-source-port-min`_.
1551
1552 .. _setting-udp-truncation-threshold:
1553
1554 ``udp-truncation-threshold``
1555 ----------------------------
1556 .. versionchanged:: 4.2.0
1557 Before 4.2.0, the default was 1680
1558
1559 - Integer
1560 - Default: 1232
1561
1562 EDNS0 allows for large UDP response datagrams, which can potentially raise performance.
1563 Large responses however also have downsides in terms of reflection attacks.
1564 This setting limits the accepted size.
1565 Maximum value is 65535, but values above 4096 should probably not be attempted.
1566
1567 To know why 1232, see the note at :ref:`setting-edns-outgoing-bufsize`.
1568
1569 .. _setting-unique-response-tracking:
1570
1571 ``unique-response-tracking``
1572 ----------------------------
1573 .. versionadded:: 4.2.0
1574
1575 - Boolean
1576 - Default: no (disabled)
1577
1578 Whether to track unique DNS responses, i.e. never seen before combinations
1579 of the triplet (query name, query type, RR[rrname, rrtype, rrdata]).
1580 This can be useful for tracking potentially suspicious domains and
1581 behaviour, e.g. DNS fast-flux.
1582 If protobuf is enabled and configured, then the Protobuf Response message
1583 will contain a flag with udr set to true for each RR that is considered
1584 unique, i.e. never seen before.
1585 This feature uses a probabilistic data structure (stable bloom filter) to
1586 track unique responses, which can have false positives as well as false
1587 negatives, thus it is a best-effort feature. Increasing the number of cells
1588 in the SBF using the unique-response-db-size setting can reduce FPs and FNs.
1589
1590 .. _setting-unique-response-log:
1591
1592 ``unique-response-log``
1593 -----------------------
1594 .. versionadded:: 4.2.0
1595
1596 - Boolean
1597 - Default: no (disabled)
1598
1599 Whether to log when a unique response is detected. The log line
1600 looks something like:
1601
1602 Oct 24 12:11:27 Unique response observed: qname=foo.com qtype=A rrtype=AAAA rrname=foo.com rrcontent=1.2.3.4
1603
1604 .. _setting-unique-response-db-size:
1605
1606 ``unique-response-db-size``
1607 ---------------------------
1608 .. versionadded:: 4.2.0
1609
1610 - Integer
1611 - Example: 67108864
1612
1613 The default size of the stable bloom filter used to store previously
1614 observed responses is 67108864. To change the number of cells, use this
1615 setting. For each cell, the SBF uses 1 bit of memory, and one byte of
1616 disk for the persistent file.
1617 If there are already persistent files saved to disk, this setting will
1618 have no effect unless you remove the existing files.
1619
1620 .. _setting-unique-response-history-dir:
1621
1622 ``unique-response-history-dir``
1623 -------------------------------
1624 .. versionadded:: 4.2.0
1625
1626 - Path
1627
1628 This setting controls which directory is used to store the on-disk
1629 cache of previously observed responses.
1630
1631 The default depends on ``LOCALSTATEDIR`` when building the software.
1632 Usually this comes down to ``/var/lib/pdns-recursor/udr`` or ``/usr/local/var/lib/pdns-recursor/udr``).
1633
1634 The newly observed domain feature uses a stable bloom filter to store
1635 a history of previously observed responses. The data structure is
1636 synchronized to disk every 10 minutes, and is also initialized from
1637 disk on startup. This ensures that previously observed responses are
1638 preserved across recursor restarts. If you change the
1639 unique-response-db-size, you must remove any files from this directory.
1640
1641 .. _setting-unique-response-pb-tag:
1642
1643 ``unique-response-pb-tag``
1644 --------------------------
1645 .. versionadded:: 4.2.0
1646
1647 - String
1648 - Default: pnds-udr
1649
1650 If protobuf is configured, then this tag will be added to all protobuf response messages when
1651 a unique DNS response is observed.
1652
1653 .. _setting-use-incoming-edns-subnet:
1654
1655 ``use-incoming-edns-subnet``
1656 ----------------------------
1657 - Boolean
1658 - Default: no
1659
1660 Whether to process and pass along a received EDNS Client Subnet to authoritative servers.
1661 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.
1662
1663 .. _setting-version:
1664
1665 ``version``
1666 -----------
1667 Print version of this binary. Useful for checking which version of the PowerDNS recursor is installed on a system.
1668
1669 .. _setting-version-string:
1670
1671 ``version-string``
1672 ------------------
1673 - String
1674 - Default: PowerDNS Recursor version number
1675
1676 By default, PowerDNS replies to the 'version.bind' query with its version number.
1677 Security conscious users may wish to override the reply PowerDNS issues.
1678
1679 .. _setting-webserver:
1680
1681 ``webserver``
1682 -------------
1683 - Boolean
1684 - Default: no
1685
1686 Start the webserver (for REST API).
1687
1688 .. _setting-webserver-address:
1689
1690 ``webserver-address``
1691 ---------------------
1692 - IP Address
1693 - Default: 127.0.0.1
1694
1695 IP address for the webserver to listen on.
1696
1697 .. _setting-webserver-allow-from:
1698
1699 ``webserver-allow-from``
1700 ------------------------
1701 - IP addresses, comma separated
1702 - Default: 127.0.0.1,::1
1703
1704 .. versionchanged:: 4.1.0
1705
1706 Default is now 127.0.0.1,::1, was 0.0.0.0,::/0 before.
1707
1708 These subnets are allowed to access the webserver.
1709
1710 .. _setting-webserver-loglevel:
1711
1712 ``webserver-loglevel``
1713 ----------------------
1714 .. versionadded:: 4.2.0
1715
1716 - String, one of "none", "normal", "detailed"
1717
1718 The amount of logging the webserver must do. "none" means no useful webserver information will be logged.
1719 When set to "normal", the webserver will log a line per request that should be familiar::
1720
1721 [webserver] e235780e-a5cf-415e-9326-9d33383e739e 127.0.0.1:55376 "GET /api/v1/servers/localhost/bla HTTP/1.1" 404 196
1722
1723 When set to "detailed", all information about the request and response are logged::
1724
1725 [webserver] e235780e-a5cf-415e-9326-9d33383e739e Request Details:
1726 [webserver] e235780e-a5cf-415e-9326-9d33383e739e Headers:
1727 [webserver] e235780e-a5cf-415e-9326-9d33383e739e accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
1728 [webserver] e235780e-a5cf-415e-9326-9d33383e739e accept-encoding: gzip, deflate
1729 [webserver] e235780e-a5cf-415e-9326-9d33383e739e accept-language: en-US,en;q=0.5
1730 [webserver] e235780e-a5cf-415e-9326-9d33383e739e connection: keep-alive
1731 [webserver] e235780e-a5cf-415e-9326-9d33383e739e dnt: 1
1732 [webserver] e235780e-a5cf-415e-9326-9d33383e739e host: 127.0.0.1:8081
1733 [webserver] e235780e-a5cf-415e-9326-9d33383e739e upgrade-insecure-requests: 1
1734 [webserver] e235780e-a5cf-415e-9326-9d33383e739e user-agent: Mozilla/5.0 (X11; Linux x86_64; rv:64.0) Gecko/20100101 Firefox/64.0
1735 [webserver] e235780e-a5cf-415e-9326-9d33383e739e No body
1736 [webserver] e235780e-a5cf-415e-9326-9d33383e739e Response details:
1737 [webserver] e235780e-a5cf-415e-9326-9d33383e739e Headers:
1738 [webserver] e235780e-a5cf-415e-9326-9d33383e739e Connection: close
1739 [webserver] e235780e-a5cf-415e-9326-9d33383e739e Content-Length: 49
1740 [webserver] e235780e-a5cf-415e-9326-9d33383e739e Content-Type: text/html; charset=utf-8
1741 [webserver] e235780e-a5cf-415e-9326-9d33383e739e Server: PowerDNS/0.0.15896.0.gaba8bab3ab
1742 [webserver] e235780e-a5cf-415e-9326-9d33383e739e Full body:
1743 [webserver] e235780e-a5cf-415e-9326-9d33383e739e <!html><title>Not Found</title><h1>Not Found</h1>
1744 [webserver] e235780e-a5cf-415e-9326-9d33383e739e 127.0.0.1:55376 "GET /api/v1/servers/localhost/bla HTTP/1.1" 404 196
1745
1746 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.
1747
1748 .. note::
1749 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.
1750
1751 .. _setting-webserver-password:
1752
1753 ``webserver-password``
1754 ----------------------
1755 - String
1756 - Default: unset
1757
1758 Password required to access the webserver.
1759
1760 .. _setting-webserver-port:
1761
1762 ``webserver-port``
1763 ------------------
1764 - Integer
1765 - Default: 8082
1766
1767 TCP port where the webserver should listen on.
1768
1769 .. _setting-write-pid:
1770
1771 ``write-pid``
1772 -------------
1773 - Boolean
1774 - Default: yes
1775
1776 If a PID file should be written to `socket-dir`_
1777
1778 .. _setting-xpf-allow-from:
1779
1780 ``xpf-allow-from``
1781 ------------------
1782 .. versionadded:: 4.2.0
1783
1784 - IP ranges, separated by commas
1785 - Default: empty
1786
1787 .. note::
1788 This is an experimental implementation of `draft-bellis-dnsop-xpf <https://datatracker.ietf.org/doc/draft-bellis-dnsop-xpf/>`_.
1789
1790 The server will trust XPF records found in queries sent from those netmasks (both IPv4 and IPv6),
1791 and will adjust queries' source and destination accordingly. This is especially useful when the recursor
1792 is placed behind a proxy like `dnsdist <https://dnsdist.org>`_.
1793 Note that the :ref:`setting-allow-from` setting is still applied to the original source address, and thus access restriction
1794 should be done on the proxy.
1795
1796 .. _setting-xpf-rr-code:
1797
1798 ``xpf-rr-code``
1799 ---------------
1800 .. versionadded:: 4.2.0
1801
1802 - Integer
1803 - Default: 0
1804
1805 .. note::
1806 This is an experimental implementation of `draft-bellis-dnsop-xpf <https://datatracker.ietf.org/doc/draft-bellis-dnsop-xpf/>`_.
1807
1808 This option sets the resource record code to use for XPF records, as long as an official code has not been assigned to it.
1809 0 means that XPF is disabled.