1 .TH "unbound.conf" "5" "Oct 6, 2015" "NLnet Labs" "unbound 1.5.5"
3 .\" unbound.conf.5 -- unbound.conf manual
5 .\" Copyright (c) 2007, NLnet Labs. All rights reserved.
7 .\" See LICENSE for the license.
12 \- Unbound configuration file.
19 The file format has attributes and values. Some attributes have attributes inside them.
20 The notation is: attribute: value.
22 Comments start with # and last to the end of line. Empty lines are
23 ignored as is whitespace at the beginning of a line.
26 \fIunbound\-checkconf\fR(8)
27 can be used to check unbound.conf prior to usage.
29 An example config file is shown below. Copy this to /etc/unbound/unbound.conf
30 and start the server with:
33 $ unbound \-c /etc/unbound/unbound.conf
36 Most settings are the defaults. Stop the server with:
39 $ kill `cat /etc/unbound/unbound.pid`
42 Below is a minimal config file. The source distribution contains an extensive
43 example.conf file with all the options.
46 # unbound.conf(5) config file for unbound(8).
48 directory: "/etc/unbound"
50 # make sure unbound can access entropy from inside the chroot.
51 # e.g. on linux the use these commands (on BSD, devfs(8) is used):
52 # mount \-\-bind \-n /dev/random /etc/unbound/dev/random
53 # and mount \-\-bind \-n /dev/log /etc/unbound/dev/log
54 chroot: "/etc/unbound"
55 # logfile: "/etc/unbound/unbound.log" #uncomment to use logfile.
56 pidfile: "/etc/unbound/unbound.pid"
57 # verbosity: 1 # uncomment and increase to get more logging.
58 # listen on all interfaces, answer queries from the local subnet.
61 access\-control: 10.0.0.0/8 allow
62 access\-control: 2001:DB8::/64 allow
65 There must be whitespace between keywords. Attribute keywords end with a colon ':'. An attribute
66 is followed by its containing attributes, or a value.
68 Files can be included using the
70 directive. It can appear anywhere, it accepts a single file name as argument.
71 Processing continues as if the text from the included file was copied into
72 the config file at that point. If also using chroot, using full path names
73 for the included files works, relative pathnames for the included names work
74 if the directory where the daemon is started equals its chroot/working
75 directory. Wildcards can be used to include multiple files, see \fIglob\fR(7).
77 These options are part of the
81 .B verbosity: \fI<number>
82 The verbosity number, level 0 means no verbosity, only errors. Level 1
83 gives operational information. Level 2 gives detailed operational
84 information. Level 3 gives query level information, output per query.
85 Level 4 gives algorithm level information. Level 5 logs client
86 identification for cache misses. Default is level 1.
87 The verbosity can also be increased from the commandline, see \fIunbound\fR(8).
89 .B statistics\-interval: \fI<seconds>
90 The number of seconds between printing statistics to the log for every thread.
91 Disable with value 0 or "". Default is disabled. The histogram statistics
92 are only printed if replies were sent during the statistics interval,
93 requestlist statistics are printed for every interval (but can be 0).
94 This is because the median calculation requires data to be present.
96 .B statistics\-cumulative: \fI<yes or no>
97 If enabled, statistics are cumulative since starting unbound, without clearing
98 the statistics counters after logging the statistics. Default is no.
100 .B extended\-statistics: \fI<yes or no>
101 If enabled, extended statistics are printed from \fIunbound\-control\fR(8).
102 Default is off, because keeping track of more statistics takes time. The
103 counters are listed in \fIunbound\-control\fR(8).
105 .B num\-threads: \fI<number>
106 The number of threads to create to serve clients. Use 1 for no threading.
108 .B port: \fI<port number>
109 The port number, default 53, on which the server responds to queries.
111 .B interface: \fI<ip address[@port]>
112 Interface to use to connect to the network. This interface is listened to
113 for queries from clients, and answers to clients are given from it.
114 Can be given multiple times to work on several interfaces. If none are
115 given the default is to listen to localhost.
116 The interfaces are not changed on a reload (kill \-HUP) but only on restart.
117 A port number can be specified with @port (without spaces between
118 interface and port number), if not specified the default port (from
121 .B ip\-address: \fI<ip address[@port]>
122 Same as interface: (for easy of compatibility with nsd.conf).
124 .B interface\-automatic: \fI<yes or no>
125 Detect source interface on UDP queries and copy them to replies. This
126 feature is experimental, and needs support in your OS for particular socket
127 options. Default value is no.
129 .B outgoing\-interface: \fI<ip address>
130 Interface to use to connect to the network. This interface is used to send
131 queries to authoritative servers and receive their replies. Can be given
132 multiple times to work on several interfaces. If none are given the
133 default (all) is used. You can specify the same interfaces in
136 .B outgoing\-interface:
137 lines, the interfaces are then used for both purposes. Outgoing queries are
138 sent via a random outgoing interface to counter spoofing.
140 .B outgoing\-range: \fI<number>
141 Number of ports to open. This number of file descriptors can be opened per
142 thread. Must be at least 1. Default depends on compile options. Larger
143 numbers need extra resources from the operating system. For performance a
144 a very large value is best, use libevent to make this possible.
146 .B outgoing\-port\-permit: \fI<port number or range>
147 Permit unbound to open this port or range of ports for use to send queries.
148 A larger number of permitted outgoing ports increases resilience against
149 spoofing attempts. Make sure these ports are not needed by other daemons.
150 By default only ports above 1024 that have not been assigned by IANA are used.
151 Give a port number or a range of the form "low\-high", without spaces.
153 The \fBoutgoing\-port\-permit\fR and \fBoutgoing\-port\-avoid\fR statements
154 are processed in the line order of the config file, adding the permitted ports
155 and subtracting the avoided ports from the set of allowed ports. The
156 processing starts with the non IANA allocated ports above 1024 in the set
159 .B outgoing\-port\-avoid: \fI<port number or range>
160 Do not permit unbound to open this port or range of ports for use to send
161 queries. Use this to make sure unbound does not grab a port that another
162 daemon needs. The port is avoided on all outgoing interfaces, both IP4 and IP6.
163 By default only ports above 1024 that have not been assigned by IANA are used.
164 Give a port number or a range of the form "low\-high", without spaces.
166 .B outgoing\-num\-tcp: \fI<number>
167 Number of outgoing TCP buffers to allocate per thread. Default is 10. If
168 set to 0, or if do\-tcp is "no", no TCP queries to authoritative servers
169 are done. For larger installations increasing this value is a good idea.
171 .B incoming\-num\-tcp: \fI<number>
172 Number of incoming TCP buffers to allocate per thread. Default is
173 10. If set to 0, or if do\-tcp is "no", no TCP queries from clients are
174 accepted. For larger installations increasing this value is a good idea.
176 .B edns\-buffer\-size: \fI<number>
177 Number of bytes size to advertise as the EDNS reassembly buffer size.
178 This is the value put into datagrams over UDP towards peers. The actual
179 buffer size is determined by msg\-buffer\-size (both for TCP and UDP). Do
180 not set higher than that value. Default is 4096 which is RFC recommended.
181 If you have fragmentation reassembly problems, usually seen as timeouts,
182 then a value of 1480 can fix it. Setting to 512 bypasses even the most
183 stringent path MTU problems, but is seen as extreme, since the amount
184 of TCP fallback generated is excessive (probably also for this resolver,
185 consider tuning the outgoing tcp number).
187 .B max\-udp\-size: \fI<number>
188 Maximum UDP response size (not applied to TCP response). 65536 disables the
189 udp response size maximum, and uses the choice from the client, always.
190 Suggested values are 512 to 4096. Default is 4096.
192 .B msg\-buffer\-size: \fI<number>
193 Number of bytes size of the message buffers. Default is 65552 bytes, enough
194 for 64 Kb packets, the maximum DNS message size. No message larger than this
195 can be sent or received. Can be reduced to use less memory, but some requests
196 for DNS data, such as for huge resource records, will result in a SERVFAIL
199 .B msg\-cache\-size: \fI<number>
200 Number of bytes size of the message cache. Default is 4 megabytes.
201 A plain number is in bytes, append 'k', 'm' or 'g' for kilobytes, megabytes
202 or gigabytes (1024*1024 bytes in a megabyte).
204 .B msg\-cache\-slabs: \fI<number>
205 Number of slabs in the message cache. Slabs reduce lock contention by threads.
206 Must be set to a power of 2. Setting (close) to the number of cpus is a
209 .B num\-queries\-per\-thread: \fI<number>
210 The number of queries that every thread will service simultaneously.
211 If more queries arrive that need servicing, and no queries can be jostled out
212 (see \fIjostle\-timeout\fR), then the queries are dropped. This forces
213 the client to resend after a timeout; allowing the server time to work on
214 the existing queries. Default depends on compile options, 512 or 1024.
216 .B jostle\-timeout: \fI<msec>
217 Timeout used when the server is very busy. Set to a value that usually
218 results in one roundtrip to the authority servers. If too many queries
219 arrive, then 50% of the queries are allowed to run to completion, and
220 the other 50% are replaced with the new incoming query if they have already
221 spent more than their allowed time. This protects against denial of
222 service by slow queries or high query rates. Default 200 milliseconds.
223 The effect is that the qps for long-lasting queries is about
224 (numqueriesperthread / 2) / (average time for such long queries) qps.
225 The qps for short queries can be about (numqueriesperthread / 2)
226 / (jostletimeout in whole seconds) qps per thread, about (1024/2)*5 = 2560
229 .B delay\-close: \fI<msec>
230 Extra delay for timeouted UDP ports before they are closed, in msec.
231 Default is 0, and that disables it. This prevents very delayed answer
232 packets from the upstream (recursive) servers from bouncing against
233 closed ports and setting off all sort of close-port counters, with
234 eg. 1500 msec. When timeouts happen you need extra sockets, it checks
235 the ID and remote IP of packets, and unwanted packets are added to the
236 unwanted packet counter.
238 .B so\-rcvbuf: \fI<number>
239 If not 0, then set the SO_RCVBUF socket option to get more buffer
240 space on UDP port 53 incoming queries. So that short spikes on busy
241 servers do not drop packets (see counter in netstat \-su). Default is
242 0 (use system value). Otherwise, the number of bytes to ask for, try
243 "4m" on a busy server. The OS caps it at a maximum, on linux unbound
244 needs root permission to bypass the limit, or the admin can use sysctl
245 net.core.rmem_max. On BSD change kern.ipc.maxsockbuf in /etc/sysctl.conf.
246 On OpenBSD change header and recompile kernel. On Solaris ndd \-set
247 /dev/udp udp_max_buf 8388608.
249 .B so\-sndbuf: \fI<number>
250 If not 0, then set the SO_SNDBUF socket option to get more buffer space on
251 UDP port 53 outgoing queries. This for very busy servers handles spikes
252 in answer traffic, otherwise 'send: resource temporarily unavailable'
253 can get logged, the buffer overrun is also visible by netstat \-su.
254 Default is 0 (use system value). Specify the number of bytes to ask
255 for, try "4m" on a very busy server. The OS caps it at a maximum, on
256 linux unbound needs root permission to bypass the limit, or the admin
257 can use sysctl net.core.wmem_max. On BSD, Solaris changes are similar
260 .B so\-reuseport: \fI<yes or no>
261 If yes, then open dedicated listening sockets for incoming queries for each
262 thread and try to set the SO_REUSEPORT socket option on each socket. May
263 distribute incoming queries to threads more evenly. Default is no. On Linux
264 it is supported in kernels >= 3.9. On other systems, FreeBSD, OSX it may
265 also work. You can enable it (on any platform and kernel),
266 it then attempts to open the port and passes the option if it was available
267 at compile time, if that works it is used, if it fails, it continues
268 silently (unless verbosity 3) without the option.
270 .B ip\-transparent: \fI<yes or no>
271 If yes, then use IP_TRANSPARENT socket option on sockets where unbound
272 is listening for incoming traffic. Default no. Allows you to bind to
273 non\-local interfaces. For example for non\-existant IP addresses that
274 are going to exist later on, with host failover configuration. This is
275 a lot like interface\-automatic, but that one services all interfaces
276 and with this option you can select which (future) interfaces unbound
277 provides service on. This option needs unbound to be started with root
278 permissions on some systems.
280 .B rrset\-cache\-size: \fI<number>
281 Number of bytes size of the RRset cache. Default is 4 megabytes.
282 A plain number is in bytes, append 'k', 'm' or 'g' for kilobytes, megabytes
283 or gigabytes (1024*1024 bytes in a megabyte).
285 .B rrset\-cache\-slabs: \fI<number>
286 Number of slabs in the RRset cache. Slabs reduce lock contention by threads.
287 Must be set to a power of 2.
289 .B cache\-max\-ttl: \fI<seconds>
290 Time to live maximum for RRsets and messages in the cache. Default is
291 86400 seconds (1 day). If the maximum kicks in, responses to clients
292 still get decrementing TTLs based on the original (larger) values.
293 When the internal TTL expires, the cache item has expired.
294 Can be set lower to force the resolver to query for data often, and not
295 trust (very large) TTL values.
297 .B cache\-min\-ttl: \fI<seconds>
298 Time to live minimum for RRsets and messages in the cache. Default is 0.
299 If the minimum kicks in, the data is cached for longer than the domain
300 owner intended, and thus less queries are made to look up the data.
301 Zero makes sure the data in the cache is as the domain owner intended,
302 higher values, especially more than an hour or so, can lead to trouble as
303 the data in the cache does not match up with the actual data any more.
305 .B cache\-max\-negative\-ttl: \fI<seconds>
306 Time to live maximum for negative responses, these have a SOA in the
307 authority section that is limited in time. Default is 3600.
309 .B infra\-host\-ttl: \fI<seconds>
310 Time to live for entries in the host cache. The host cache contains
311 roundtrip timing, lameness and EDNS support information. Default is 900.
313 .B infra\-cache\-slabs: \fI<number>
314 Number of slabs in the infrastructure cache. Slabs reduce lock contention
315 by threads. Must be set to a power of 2.
317 .B infra\-cache\-numhosts: \fI<number>
318 Number of hosts for which information is cached. Default is 10000.
320 .B infra\-cache\-min\-rtt: \fI<msec>
321 Lower limit for dynamic retransmit timeout calculation in infrastructure
322 cache. Default is 50 milliseconds. Increase this value if using forwarders
323 needing more time to do recursive name resolution.
325 .B do\-ip4: \fI<yes or no>
326 Enable or disable whether ip4 queries are answered or issued. Default is yes.
328 .B do\-ip6: \fI<yes or no>
329 Enable or disable whether ip6 queries are answered or issued. Default is yes.
330 If disabled, queries are not answered on IPv6, and queries are not sent on
331 IPv6 to the internet nameservers. With this option you can disable the
332 ipv6 transport for sending DNS traffic, it does not impact the contents of
333 the DNS traffic, which may have ip4 and ip6 addresses in it.
335 .B do\-udp: \fI<yes or no>
336 Enable or disable whether UDP queries are answered or issued. Default is yes.
338 .B do\-tcp: \fI<yes or no>
339 Enable or disable whether TCP queries are answered or issued. Default is yes.
341 .B tcp\-upstream: \fI<yes or no>
342 Enable or disable whether the upstream queries use TCP only for transport.
343 Default is no. Useful in tunneling scenarios.
345 .B ssl\-upstream: \fI<yes or no>
346 Enabled or disable whether the upstream queries use SSL only for transport.
347 Default is no. Useful in tunneling scenarios. The SSL contains plain DNS in
348 TCP wireformat. The other server must support this (see \fBssl\-service\-key\fR).
350 .B ssl\-service-key: \fI<file>
351 If enabled, the server provider SSL service on its TCP sockets. The clients
352 have to use ssl\-upstream: yes. The file is the private key for the TLS
353 session. The public certificate is in the ssl\-service\-pem file. Default
354 is "", turned off. Requires a restart (a reload is not enough) if changed,
355 because the private key is read while root permissions are held and before
356 chroot (if any). Normal DNS TCP service is not provided and gives errors,
357 this service is best run with a different \fBport:\fR config or \fI@port\fR
358 suffixes in the \fBinterface\fR config.
360 .B ssl\-service\-pem: \fI<file>
361 The public key certificate pem file for the ssl service. Default is "",
364 .B ssl\-port: \fI<number>
365 The port number on which to provide TCP SSL service, default 443, only
366 interfaces configured with that port number as @number get the SSL service.
368 .B do\-daemonize: \fI<yes or no>
369 Enable or disable whether the unbound server forks into the background as
370 a daemon. Default is yes.
372 .B access\-control: \fI<IP netblock> <action>
373 The netblock is given as an IP4 or IP6 address with /size appended for a
374 classless network block. The action can be \fIdeny\fR, \fIrefuse\fR,
375 \fIallow\fR, \fIallow_snoop\fR, \fIdeny_non_local\fR or \fIrefuse_non_local\fR.
376 The most specific netblock match is used, if none match \fIdeny\fR is used.
378 The action \fIdeny\fR stops queries from hosts from that netblock.
380 The action \fIrefuse\fR stops queries too, but sends a DNS rcode REFUSED
383 The action \fIallow\fR gives access to clients from that netblock.
384 It gives only access for recursion clients (which is
385 what almost all clients need). Nonrecursive queries are refused.
387 The \fIallow\fR action does allow nonrecursive queries to access the
388 local\-data that is configured. The reason is that this does not involve
389 the unbound server recursive lookup algorithm, and static data is served
390 in the reply. This supports normal operations where nonrecursive queries
391 are made for the authoritative data. For nonrecursive queries any replies
392 from the dynamic cache are refused.
394 The action \fIallow_snoop\fR gives nonrecursive access too. This give
395 both recursive and non recursive access. The name \fIallow_snoop\fR refers
396 to cache snooping, a technique to use nonrecursive queries to examine
397 the cache contents (for malicious acts). However, nonrecursive queries can
398 also be a valuable debugging tool (when you want to examine the cache
399 contents). In that case use \fIallow_snoop\fR for your administration host.
401 By default only localhost is \fIallow\fRed, the rest is \fIrefuse\fRd.
402 The default is \fIrefuse\fRd, because that is protocol\-friendly. The DNS
403 protocol is not designed to handle dropped packets due to policy, and
404 dropping may result in (possibly excessive) retried queries.
406 The deny_non_local and refuse_non_local settings are for hosts that are
407 only allowed to query for the authoritative local\-data, they are not
408 allowed full recursion but only the static data. With deny_non_local,
409 messages that are disallowed are dropped, with refuse_non_local they
410 receive error code REFUSED.
412 .B chroot: \fI<directory>
413 If chroot is enabled, you should pass the configfile (from the
414 commandline) as a full path from the original root. After the
415 chroot has been performed the now defunct portion of the config
416 file path is removed to be able to reread the config after a reload.
418 All other file paths (working dir, logfile, roothints, and
419 key files) can be specified in several ways:
420 as an absolute path relative to the new root,
421 as a relative path to the working directory, or
422 as an absolute path relative to the original root.
423 In the last case the path is adjusted to remove the unused portion.
425 The pidfile can be either a relative path to the working directory, or
426 an absolute path relative to the original root. It is written just prior
427 to chroot and dropping permissions. This allows the pidfile to be
428 /var/run/unbound.pid and the chroot to be /var/unbound, for example.
430 Additionally, unbound may need to access /dev/random (for entropy)
431 from inside the chroot.
433 If given a chroot is done to the given directory. The default is
434 "@UNBOUND_CHROOT_DIR@". If you give "" no chroot is performed.
436 .B username: \fI<name>
437 If given, after binding the port the user privileges are dropped. Default is
438 "@UNBOUND_USERNAME@". If you give username: "" no user change is performed.
440 If this user is not capable of binding the
441 port, reloads (by signal HUP) will still retain the opened ports.
442 If you change the port number in the config file, and that new port number
443 requires privileges, then a reload will fail; a restart is needed.
445 .B directory: \fI<directory>
446 Sets the working directory for the program. Default is "@UNBOUND_RUN_DIR@".
448 .B logfile: \fI<filename>
449 If "" is given, logging goes to stderr, or nowhere once daemonized.
450 The logfile is appended to, in the following format:
452 [seconds since 1970] unbound[pid:tid]: type: message.
454 If this option is given, the use\-syslog is option is set to "no".
455 The logfile is reopened (for append) when the config file is reread, on
458 .B use\-syslog: \fI<yes or no>
459 Sets unbound to send log messages to the syslogd, using
461 The log facility LOG_DAEMON is used, with identity "unbound".
462 The logfile setting is overridden when use\-syslog is turned on.
463 The default is to log to syslog.
465 .B log\-time\-ascii: \fI<yes or no>
466 Sets logfile lines to use a timestamp in UTC ascii. Default is no, which
467 prints the seconds since 1970 in brackets. No effect if using syslog, in
468 that case syslog formats the timestamp printed into the log files.
470 .B log\-queries: \fI<yes or no>
471 Prints one line per query to the log, with the log timestamp and IP address,
472 name, type and class. Default is no. Note that it takes time to print these
473 lines which makes the server (significantly) slower. Odd (nonprintable)
474 characters in names are printed as '?'.
476 .B pidfile: \fI<filename>
477 The process id is written to the file. Default is "@UNBOUND_PIDFILE@".
480 kill \-HUP `cat @UNBOUND_PIDFILE@`
484 kill \-TERM `cat @UNBOUND_PIDFILE@`
486 gracefully terminates.
488 .B root\-hints: \fI<filename>
489 Read the root hints from this file. Default is nothing, using builtin hints
490 for the IN class. The file has the format of zone files, with root
491 nameserver names and addresses only. The default may become outdated,
492 when servers change, therefore it is good practice to use a root\-hints file.
494 .B hide\-identity: \fI<yes or no>
495 If enabled id.server and hostname.bind queries are refused.
497 .B identity: \fI<string>
498 Set the identity to report. If set to "", the default, then the hostname
499 of the server is returned.
501 .B hide\-version: \fI<yes or no>
502 If enabled version.server and version.bind queries are refused.
504 .B version: \fI<string>
505 Set the version to report. If set to "", the default, then the package
508 .B target\-fetch\-policy: \fI<"list of numbers">
509 Set the target fetch policy used by unbound to determine if it should fetch
510 nameserver target addresses opportunistically. The policy is described per
513 The number of values determines the maximum dependency depth
514 that unbound will pursue in answering a query.
515 A value of \-1 means to fetch all targets opportunistically for that dependency
516 depth. A value of 0 means to fetch on demand only. A positive value fetches
517 that many targets opportunistically.
519 Enclose the list between quotes ("") and put spaces between numbers.
520 The default is "3 2 1 0 0". Setting all zeroes, "0 0 0 0 0" gives behaviour
521 closer to that of BIND 9, while setting "\-1 \-1 \-1 \-1 \-1" gives behaviour
522 rumoured to be closer to that of BIND 8.
524 .B harden\-short\-bufsize: \fI<yes or no>
525 Very small EDNS buffer sizes from queries are ignored. Default is off, since
526 it is legal protocol wise to send these, and unbound tries to give very
527 small answers to these queries, where possible.
529 .B harden\-large\-queries: \fI<yes or no>
530 Very large queries are ignored. Default is off, since it is legal protocol
531 wise to send these, and could be necessary for operation if TSIG or EDNS
532 payload is very large.
534 .B harden\-glue: \fI<yes or no>
535 Will trust glue only if it is within the servers authority. Default is on.
537 .B harden\-dnssec\-stripped: \fI<yes or no>
538 Require DNSSEC data for trust\-anchored zones, if such data is absent,
539 the zone becomes bogus. If turned off, and no DNSSEC data is received
540 (or the DNSKEY data fails to validate), then the zone is made insecure,
541 this behaves like there is no trust anchor. You could turn this off if
542 you are sometimes behind an intrusive firewall (of some sort) that
543 removes DNSSEC data from packets, or a zone changes from signed to
544 unsigned to badly signed often. If turned off you run the risk of a
545 downgrade attack that disables security for a zone. Default is on.
547 .B harden\-below\-nxdomain: \fI<yes or no>
548 From draft\-vixie\-dnsext\-resimprove, returns nxdomain to queries for a name
549 below another name that is already known to be nxdomain. DNSSEC mandates
550 noerror for empty nonterminals, hence this is possible. Very old software
551 might return nxdomain for empty nonterminals (that usually happen for reverse
552 IP address lookups), and thus may be incompatible with this. To try to avoid
553 this only DNSSEC-secure nxdomains are used, because the old software does not
554 have DNSSEC. Default is off.
556 .B harden\-referral\-path: \fI<yes or no>
557 Harden the referral path by performing additional queries for
558 infrastructure data. Validates the replies if trust anchors are configured
559 and the zones are signed. This enforces DNSSEC validation on nameserver
560 NS sets and the nameserver addresses that are encountered on the referral
562 Default off, because it burdens the authority servers, and it is
563 not RFC standard, and could lead to performance problems because of the
564 extra query load that is generated. Experimental option.
565 If you enable it consider adding more numbers after the target\-fetch\-policy
566 to increase the max depth that is checked to.
568 .B harden\-algo\-downgrade: \fI<yes or no>
569 Harden against algorithm downgrade when multiple algorithms are
570 advertised in the DS record. If no, allows the weakest algorithm to
571 validate the zone. Default is no. Zone signers must produce zones
572 that allow this feature to work, but sometimes they do not, and turning
573 this option off avoids that validation failure.
575 .B use\-caps\-for\-id: \fI<yes or no>
576 Use 0x20\-encoded random bits in the query to foil spoof attempts.
577 This perturbs the lowercase and uppercase of query names sent to
578 authority servers and checks if the reply still has the correct casing.
580 This feature is an experimental implementation of draft dns\-0x20.
582 .B caps\-whitelist: \fI<domain>
583 Whitelist the domain so that it does not receive caps\-for\-id perturbed
584 queries. For domains that do not support 0x20 and also fail with fallback
585 because they keep sending different answers, like some load balancers.
586 Can be given multiple times, for different domains.
588 .B private\-address: \fI<IP address or subnet>
589 Give IPv4 of IPv6 addresses or classless subnets. These are addresses
590 on your private network, and are not allowed to be returned for public
591 internet names. Any occurence of such addresses are removed from
592 DNS answers. Additionally, the DNSSEC validator may mark the answers
593 bogus. This protects against so\-called DNS Rebinding, where a user browser
594 is turned into a network proxy, allowing remote access through the browser
595 to other parts of your private network. Some names can be allowed to
596 contain your private addresses, by default all the \fBlocal\-data\fR
597 that you configured is allowed to, and you can specify additional
598 names using \fBprivate\-domain\fR. No private addresses are enabled
599 by default. We consider to enable this for the RFC1918 private IP
600 address space by default in later releases. That would enable private
601 addresses for 10.0.0.0/8 172.16.0.0/12 192.168.0.0/16 169.254.0.0/16
602 fd00::/8 and fe80::/10, since the RFC standards say these addresses
603 should not be visible on the public internet. Turning on 127.0.0.0/8
604 would hinder many spamblocklists as they use that.
606 .B private\-domain: \fI<domain name>
607 Allow this domain, and all its subdomains to contain private addresses.
608 Give multiple times to allow multiple domain names to contain private
609 addresses. Default is none.
611 .B unwanted\-reply\-threshold: \fI<number>
612 If set, a total number of unwanted replies is kept track of in every thread.
613 When it reaches the threshold, a defensive action is taken and a warning
614 is printed to the log. The defensive action is to clear the rrset and
615 message caches, hopefully flushing away any poison. A value of 10 million
616 is suggested. Default is 0 (turned off).
618 .B do\-not\-query\-address: \fI<IP address>
619 Do not query the given IP address. Can be IP4 or IP6. Append /num to
620 indicate a classless delegation netblock, for example like
621 10.2.3.4/24 or 2001::11/64.
623 .B do\-not\-query\-localhost: \fI<yes or no>
624 If yes, localhost is added to the do\-not\-query\-address entries, both
625 IP6 ::1 and IP4 127.0.0.1/8. If no, then localhost can be used to send
626 queries to. Default is yes.
628 .B prefetch: \fI<yes or no>
629 If yes, message cache elements are prefetched before they expire to
630 keep the cache up to date. Default is no. Turning it on gives about
631 10 percent more traffic and load on the machine, but popular items do
632 not expire from the cache.
634 .B prefetch-key: \fI<yes or no>
635 If yes, fetch the DNSKEYs earlier in the validation process, when a DS
636 record is encountered. This lowers the latency of requests. It does use
637 a little more CPU. Also if the cache is set to 0, it is no use. Default is no.
639 .B rrset-roundrobin: \fI<yes or no>
640 If yes, Unbound rotates RRSet order in response (the random number is taken
641 from the query ID, for speed and thread safety). Default is no.
643 .B minimal-responses: \fI<yes or no>
644 If yes, Unbound doesn't insert authority/additional sections into response
645 messages when those sections are not required. This reduces response
646 size significantly, and may avoid TCP fallback for some responses.
647 This may cause a slight speedup. The default is no, because the DNS
648 protocol RFCs mandate these sections, and the additional content could
649 be of use and save roundtrips for clients.
651 .B module\-config: \fI<"module names">
652 Module configuration, a list of module names separated by spaces, surround
653 the string with quotes (""). The modules can be validator, iterator.
654 Setting this to "iterator" will result in a non\-validating server.
655 Setting this to "validator iterator" will turn on DNSSEC validation.
656 The ordering of the modules is important.
657 You must also set trust\-anchors for validation to be useful.
659 .B trust\-anchor\-file: \fI<filename>
660 File with trusted keys for validation. Both DS and DNSKEY entries can appear
661 in the file. The format of the file is the standard DNS Zone file format.
662 Default is "", or no trust anchor file.
664 .B auto\-trust\-anchor\-file: \fI<filename>
665 File with trust anchor for one zone, which is tracked with RFC5011 probes.
666 The probes are several times per month, thus the machine must be online
667 frequently. The initial file can be one with contents as described in
668 \fBtrust\-anchor\-file\fR. The file is written to when the anchor is updated,
669 so the unbound user must have write permission.
671 .B trust\-anchor: \fI<"Resource Record">
672 A DS or DNSKEY RR for a key to use for validation. Multiple entries can be
673 given to specify multiple trusted keys, in addition to the trust\-anchor\-files.
674 The resource record is entered in the same format as 'dig' or 'drill' prints
675 them, the same format as in the zone file. Has to be on a single line, with
676 "" around it. A TTL can be specified for ease of cut and paste, but is ignored.
677 A class can be specified, but class IN is default.
679 .B trusted\-keys\-file: \fI<filename>
680 File with trusted keys for validation. Specify more than one file
681 with several entries, one file per entry. Like \fBtrust\-anchor\-file\fR
682 but has a different file format. Format is BIND\-9 style format,
683 the trusted\-keys { name flag proto algo "key"; }; clauses are read.
684 It is possible to use wildcards with this statement, the wildcard is
685 expanded on start and on reload.
687 .B dlv\-anchor\-file: \fI<filename>
688 This option was used during early days DNSSEC deployment when no parent-side
689 DS record registrations were easily available. Nowadays, it is best to have
690 DS records registered with the parent zone (many top level zones are signed).
691 File with trusted keys for DLV (DNSSEC Lookaside Validation). Both DS and
692 DNSKEY entries can be used in the file, in the same format as for
693 \fItrust\-anchor\-file:\fR statements. Only one DLV can be configured, more
694 would be slow. The DLV configured is used as a root trusted DLV, this
695 means that it is a lookaside for the root. Default is "", or no dlv anchor file.
696 DLV is going to be decommissioned. Please do not use it any more.
698 .B dlv\-anchor: \fI<"Resource Record">
699 Much like trust\-anchor, this is a DLV anchor with the DS or DNSKEY inline.
700 DLV is going to be decommissioned. Please do not use it any more.
702 .B domain\-insecure: \fI<domain name>
703 Sets domain name to be insecure, DNSSEC chain of trust is ignored towards
704 the domain name. So a trust anchor above the domain name can not make the
705 domain secure with a DS record, such a DS record is then ignored.
706 Also keys from DLV are ignored for the domain. Can be given multiple times
707 to specify multiple domains that are treated as if unsigned. If you set
708 trust anchors for the domain they override this setting (and the domain
711 This can be useful if you want to make sure a trust anchor for external
712 lookups does not affect an (unsigned) internal domain. A DS record
713 externally can create validation failures for that internal domain.
715 .B val\-override\-date: \fI<rrsig\-style date spec>
716 Default is "" or "0", which disables this debugging feature. If enabled by
717 giving a RRSIG style date, that date is used for verifying RRSIG inception
718 and expiration dates, instead of the current date. Do not set this unless
719 you are debugging signature inception and expiration. The value \-1 ignores
720 the date altogether, useful for some special applications.
722 .B val\-sig\-skew\-min: \fI<seconds>
723 Minimum number of seconds of clock skew to apply to validated signatures.
724 A value of 10% of the signature lifetime (expiration \- inception) is
725 used, capped by this setting. Default is 3600 (1 hour) which allows for
726 daylight savings differences. Lower this value for more strict checking
727 of short lived signatures.
729 .B val\-sig\-skew\-max: \fI<seconds>
730 Maximum number of seconds of clock skew to apply to validated signatures.
731 A value of 10% of the signature lifetime (expiration \- inception)
732 is used, capped by this setting. Default is 86400 (24 hours) which
733 allows for timezone setting problems in stable domains. Setting both
734 min and max very low disables the clock skew allowances. Setting both
735 min and max very high makes the validator check the signature timestamps
738 .B val\-bogus\-ttl: \fI<number>
739 The time to live for bogus data. This is data that has failed validation;
740 due to invalid signatures or other checks. The TTL from that data cannot be
741 trusted, and this value is used instead. The value is in seconds, default 60.
742 The time interval prevents repeated revalidation of bogus data.
744 .B val\-clean\-additional: \fI<yes or no>
745 Instruct the validator to remove data from the additional section of secure
746 messages that are not signed properly. Messages that are insecure, bogus,
747 indeterminate or unchecked are not affected. Default is yes. Use this setting
748 to protect the users that rely on this validator for authentication from
749 protentially bad data in the additional section.
751 .B val\-log\-level: \fI<number>
752 Have the validator print validation failures to the log. Regardless of
753 the verbosity setting. Default is 0, off. At 1, for every user query
754 that fails a line is printed to the logs. This way you can monitor what
755 happens with validation. Use a diagnosis tool, such as dig or drill,
756 to find out why validation is failing for these queries. At 2, not only
757 the query that failed is printed but also the reason why unbound thought
758 it was wrong and which server sent the faulty data.
760 .B val\-permissive\-mode: \fI<yes or no>
761 Instruct the validator to mark bogus messages as indeterminate. The security
762 checks are performed, but if the result is bogus (failed security), the
763 reply is not withheld from the client with SERVFAIL as usual. The client
764 receives the bogus data. For messages that are found to be secure the AD bit
765 is set in replies. Also logging is performed as for full validation.
766 The default value is "no".
768 .B ignore\-cd\-flag: \fI<yes or no>
769 Instruct unbound to ignore the CD flag from clients and refuse to
770 return bogus answers to them. Thus, the CD (Checking Disabled) flag
771 does not disable checking any more. This is useful if legacy (w2008)
772 servers that set the CD flag but cannot validate DNSSEC themselves are
773 the clients, and then unbound provides them with DNSSEC protection.
774 The default value is "no".
776 .B val\-nsec3\-keysize\-iterations: \fI<"list of values">
777 List of keysize and iteration count values, separated by spaces, surrounded
778 by quotes. Default is "1024 150 2048 500 4096 2500". This determines the
779 maximum allowed NSEC3 iteration count before a message is simply marked
780 insecure instead of performing the many hashing iterations. The list must
781 be in ascending order and have at least one entry. If you set it to
782 "1024 65535" there is no restriction to NSEC3 iteration values.
783 This table must be kept short; a very long list could cause slower operation.
785 .B add\-holddown: \fI<seconds>
786 Instruct the \fBauto\-trust\-anchor\-file\fR probe mechanism for RFC5011
787 autotrust updates to add new trust anchors only after they have been
788 visible for this time. Default is 30 days as per the RFC.
790 .B del\-holddown: \fI<seconds>
791 Instruct the \fBauto\-trust\-anchor\-file\fR probe mechanism for RFC5011
792 autotrust updates to remove revoked trust anchors after they have been
793 kept in the revoked list for this long. Default is 30 days as per
796 .B keep\-missing: \fI<seconds>
797 Instruct the \fBauto\-trust\-anchor\-file\fR probe mechanism for RFC5011
798 autotrust updates to remove missing trust anchors after they have been
799 unseen for this long. This cleans up the state file if the target zone
800 does not perform trust anchor revocation, so this makes the auto probe
801 mechanism work with zones that perform regular (non\-5011) rollovers.
802 The default is 366 days. The value 0 does not remove missing anchors,
805 .B permit\-small\-holddown: \fI<yes or no>
806 Debug option that allows the autotrust 5011 rollover timers to assume
807 very small values. Default is no.
809 .B key\-cache\-size: \fI<number>
810 Number of bytes size of the key cache. Default is 4 megabytes.
811 A plain number is in bytes, append 'k', 'm' or 'g' for kilobytes, megabytes
812 or gigabytes (1024*1024 bytes in a megabyte).
814 .B key\-cache\-slabs: \fI<number>
815 Number of slabs in the key cache. Slabs reduce lock contention by threads.
816 Must be set to a power of 2. Setting (close) to the number of cpus is a
819 .B neg\-cache\-size: \fI<number>
820 Number of bytes size of the aggressive negative cache. Default is 1 megabyte.
821 A plain number is in bytes, append 'k', 'm' or 'g' for kilobytes, megabytes
822 or gigabytes (1024*1024 bytes in a megabyte).
824 .B unblock\-lan\-zones: \fI<yesno>
825 Default is disabled. If enabled, then for private address space,
826 the reverse lookups are no longer filtered. This allows unbound when
827 running as dns service on a host where it provides service for that host,
828 to put out all of the queries for the 'lan' upstream. When enabled,
829 only localhost, 127.0.0.1 reverse and ::1 reverse zones are configured
830 with default local zones. Disable the option when unbound is running
831 as a (DHCP-) DNS network resolver for a group of machines, where such
832 lookups should be filtered (RFC compliance), this also stops potential
833 data leakage about the local network to the upstream DNS servers.
835 .B local\-zone: \fI<zone> <type>
836 Configure a local zone. The type determines the answer to give if
837 there is no match from local\-data. The types are deny, refuse, static,
838 transparent, redirect, nodefault, typetransparent, inform, inform_deny,
839 and are explained below. After that the default settings are listed. Use
840 local\-data: to enter data into the local zone. Answers for local zones
841 are authoritative DNS answers. By default the zones are class IN.
843 If you need more complicated authoritative data, with referrals, wildcards,
844 CNAME/DNAME support, or DNSSEC authoritative service, setup a stub\-zone for
845 it as detailed in the stub zone section below.
848 Do not send an answer, drop the query.
849 If there is a match from local data, the query is answered.
852 Send an error message reply, with rcode REFUSED.
853 If there is a match from local data, the query is answered.
856 If there is a match from local data, the query is answered.
857 Otherwise, the query is answered with nodata or nxdomain.
858 For a negative answer a SOA is included in the answer if present
859 as local\-data for the zone apex domain.
861 \h'5'\fItransparent\fR
862 If there is a match from local data, the query is answered.
863 Otherwise if the query has a different name, the query is resolved normally.
864 If the query is for a name given in localdata but no such type of data is
865 given in localdata, then a noerror nodata answer is returned.
866 If no local\-zone is given local\-data causes a transparent zone
867 to be created by default.
869 \h'5'\fItypetransparent\fR
870 If there is a match from local data, the query is answered. If the query
871 is for a different name, or for the same name but for a different type,
872 the query is resolved normally. So, similar to transparent but types
873 that are not listed in local data are resolved normally, so if an A record
874 is in the local data that does not cause a nodata reply for AAAA queries.
877 The query is answered from the local data for the zone name.
878 There may be no local data beneath the zone name.
879 This answers queries for the zone, and all subdomains of the zone
880 with the local data for the zone.
881 It can be used to redirect a domain to return a different address record
882 to the end user, with
883 local\-zone: "example.com." redirect and
884 local\-data: "example.com. A 127.0.0.1"
885 queries for www.example.com and www.foo.example.com are redirected, so
886 that users with web browsers cannot access sites with suffix example.com.
889 The query is answered normally. The client IP address (@portnumber)
890 is printed to the logfile. The log message is: timestamp, unbound-pid,
891 info: zonename inform IP@port queryname type class. This option can be
892 used for normal resolution, but machines looking up infected names are
893 logged, eg. to run antivirus on them.
895 \h'5'\fIinform_deny\fR
896 The query is dropped, like 'deny', and logged, like 'inform'. Ie. find
897 infected machines without answering the queries.
900 Used to turn off default contents for AS112 zones. The other types
901 also turn off default contents for the zone. The 'nodefault' option
902 has no other effect than turning off default contents for the
903 given zone. Use \fInodefault\fR if you use exactly that zone, if you want to
904 use a subzone, use \fItransparent\fR.
906 The default zones are localhost, reverse 127.0.0.1 and ::1, and the AS112
907 zones. The AS112 zones are reverse DNS zones for private use and reserved
908 IP addresses for which the servers on the internet cannot provide correct
909 answers. They are configured by default to give nxdomain (no reverse
910 information) answers. The defaults can be turned off by specifying your
911 own local\-zone of that name, or using the 'nodefault' type. Below is a
912 list of the default zone contents.
915 The IP4 and IP6 localhost information is given. NS and SOA records are provided
916 for completeness and to satisfy some DNS update tools. Default content:
918 local\-zone: "localhost." static
919 local\-data: "localhost. 10800 IN NS localhost."
920 local\-data: "localhost. 10800 IN
921 SOA localhost. nobody.invalid. 1 3600 1200 604800 10800"
922 local\-data: "localhost. 10800 IN A 127.0.0.1"
923 local\-data: "localhost. 10800 IN AAAA ::1"
926 \h'5'\fIreverse IPv4 loopback\fR
929 local\-zone: "127.in\-addr.arpa." static
930 local\-data: "127.in\-addr.arpa. 10800 IN NS localhost."
931 local\-data: "127.in\-addr.arpa. 10800 IN
932 SOA localhost. nobody.invalid. 1 3600 1200 604800 10800"
933 local\-data: "1.0.0.127.in\-addr.arpa. 10800 IN
937 \h'5'\fIreverse IPv6 loopback\fR
940 local\-zone: "1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.
941 0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.ip6.arpa." static
942 local\-data: "1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.
943 0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.ip6.arpa. 10800 IN
945 local\-data: "1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.
946 0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.ip6.arpa. 10800 IN
947 SOA localhost. nobody.invalid. 1 3600 1200 604800 10800"
948 local\-data: "1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.
949 0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.ip6.arpa. 10800 IN
953 \h'5'\fIreverse RFC1918 local use zones\fR
954 Reverse data for zones 10.in\-addr.arpa, 16.172.in\-addr.arpa to
955 31.172.in\-addr.arpa, 168.192.in\-addr.arpa.
956 The \fBlocal\-zone:\fR is set static and as \fBlocal\-data:\fR SOA and NS
957 records are provided.
959 \h'5'\fIreverse RFC3330 IP4 this, link\-local, testnet and broadcast\fR
960 Reverse data for zones 0.in\-addr.arpa, 254.169.in\-addr.arpa,
961 2.0.192.in\-addr.arpa (TEST NET 1), 100.51.198.in\-addr.arpa (TEST NET 2),
962 113.0.203.in\-addr.arpa (TEST NET 3), 255.255.255.255.in\-addr.arpa.
963 And from 64.100.in\-addr.arpa to 127.100.in\-addr.arpa (Shared Address Space).
965 \h'5'\fIreverse RFC4291 IP6 unspecified\fR
966 Reverse data for zone
968 0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.
969 0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.ip6.arpa.
972 \h'5'\fIreverse RFC4193 IPv6 Locally Assigned Local Addresses\fR
973 Reverse data for zone D.F.ip6.arpa.
975 \h'5'\fIreverse RFC4291 IPv6 Link Local Addresses\fR
976 Reverse data for zones 8.E.F.ip6.arpa to B.E.F.ip6.arpa.
978 \h'5'\fIreverse IPv6 Example Prefix\fR
979 Reverse data for zone 8.B.D.0.1.0.0.2.ip6.arpa. This zone is used for
980 tutorials and examples. You can remove the block on this zone with:
982 local\-zone: 8.B.D.0.1.0.0.2.ip6.arpa. nodefault
984 You can also selectively unblock a part of the zone by making that part
985 transparent with a local\-zone statement.
986 This also works with the other default zones.
987 .\" End of local-zone listing.
989 .B local\-data: \fI"<resource record string>"
990 Configure local data, which is served in reply to queries for it.
991 The query has to match exactly unless you configure the local\-zone as
992 redirect. If not matched exactly, the local\-zone type determines
993 further processing. If local\-data is configured that is not a subdomain of
994 a local\-zone, a transparent local\-zone is configured.
995 For record types such as TXT, use single quotes, as in
996 local\-data: 'example. TXT "text"'.
998 If you need more complicated authoritative data, with referrals, wildcards,
999 CNAME/DNAME support, or DNSSEC authoritative service, setup a stub\-zone for
1000 it as detailed in the stub zone section below.
1002 .B local\-data\-ptr: \fI"IPaddr name"
1003 Configure local data shorthand for a PTR record with the reversed IPv4 or
1004 IPv6 address and the host name. For example "192.0.2.4 www.example.com".
1005 TTL can be inserted like this: "2001:DB8::4 7200 www.example.com"
1007 .B ratelimit: \fI<number or 0>
1008 Enable ratelimiting of queries sent to nameserver for performing recursion.
1009 If 0, the default, it is disabled. This option is experimental at this time.
1010 The ratelimit is in queries per second that are allowed. More queries are
1011 turned away with an error (servfail). This stops recursive floods, eg. random
1012 query names, but not spoofed reflection floods. Cached responses are not
1013 ratelimited by this setting. The zone of the query is determined by examining
1014 the nameservers for it, the zone name is used to keep track of the rate.
1015 For example, 1000 may be a suitable value to stop the server from being
1016 overloaded with random names, and keeps unbound from sending traffic to the
1017 nameservers for those zones.
1019 .B ratelimit\-size: \fI<memory size>
1020 Give the size of the data structure in which the current ongoing rates are
1021 kept track in. Default 4m. In bytes or use m(mega), k(kilo), g(giga).
1022 The ratelimit structure is small, so this data structure likely does
1023 not need to be large.
1025 .B ratelimit\-slabs: \fI<number>
1026 Give power of 2 number of slabs, this is used to reduce lock contention
1027 in the ratelimit tracking data structure. Close to the number of cpus is
1028 a fairly good setting.
1030 .B ratelimit\-factor: \fI<number>
1031 Set the amount of queries to rate limit when the limit is exceeded.
1032 If set to 0, all queries are dropped for domains where the limit is
1033 exceeded. If set to another value, 1 in that number is allowed through
1034 to complete. Default is 10, allowing 1/10 traffic to flow normally.
1035 This can make ordinary queries complete (if repeatedly queried for),
1036 and enter the cache, whilst also mitigiting the traffic flow by the
1039 .B ratelimit\-for\-domain: \fI<domain> <number qps>
1040 Override the global ratelimit for an exact match domain name with the listed
1041 number. You can give this for any number of names. For example, for
1042 a top\-level\-domain you may want to have a higher limit than other names.
1044 .B ratelimit\-below\-domain: \fI<domain> <number qps>
1045 Override the global ratelimit for a domain name that ends in this name.
1046 You can give this multiple times, it then describes different settings
1047 in different parts of the namespace. The closest matching suffix is used
1048 to determine the qps limit. The rate for the exact matching domain name
1049 is not changed, use ratelimit\-for\-domain to set that, you might want
1050 to use different settings for a top\-level\-domain and subdomains.
1051 .SS "Remote Control Options"
1054 clause are the declarations for the remote control facility. If this is
1055 enabled, the \fIunbound\-control\fR(8) utility can be used to send
1056 commands to the running unbound server. The server uses these clauses
1057 to setup SSLv3 / TLSv1 security for the connection. The
1058 \fIunbound\-control\fR(8) utility also reads the \fBremote\-control\fR
1059 section for options. To setup the correct self\-signed certificates use the
1060 \fIunbound\-control\-setup\fR(8) utility.
1062 .B control\-enable: \fI<yes or no>
1063 The option is used to enable remote control, default is "no".
1064 If turned off, the server does not listen for control commands.
1066 .B control\-interface: \fI<ip address or path>
1067 Give IPv4 or IPv6 addresses or local socket path to listen on for
1069 By default localhost (127.0.0.1 and ::1) is listened to.
1070 Use 0.0.0.0 and ::0 to listen to all interfaces.
1071 If you change this and permissions have been dropped, you must restart
1072 the server for the change to take effect.
1074 .B control\-port: \fI<port number>
1075 The port number to listen on for IPv4 or IPv6 control interfaces,
1077 If you change this and permissions have been dropped, you must restart
1078 the server for the change to take effect.
1080 .B control\-use\-cert: \fI<yes or no>
1081 Whether to require certificate authentication of control connections.
1082 The default is "yes".
1083 This should not be changed unless there are other mechanisms in place
1084 to prevent untrusted users from accessing the remote control
1087 .B server\-key\-file: \fI<private key file>
1088 Path to the server private key, by default unbound_server.key.
1089 This file is generated by the \fIunbound\-control\-setup\fR utility.
1090 This file is used by the unbound server, but not by \fIunbound\-control\fR.
1092 .B server\-cert\-file: \fI<certificate file.pem>
1093 Path to the server self signed certificate, by default unbound_server.pem.
1094 This file is generated by the \fIunbound\-control\-setup\fR utility.
1095 This file is used by the unbound server, and also by \fIunbound\-control\fR.
1097 .B control\-key\-file: \fI<private key file>
1098 Path to the control client private key, by default unbound_control.key.
1099 This file is generated by the \fIunbound\-control\-setup\fR utility.
1100 This file is used by \fIunbound\-control\fR.
1102 .B control\-cert\-file: \fI<certificate file.pem>
1103 Path to the control client certificate, by default unbound_control.pem.
1104 This certificate has to be signed with the server certificate.
1105 This file is generated by the \fIunbound\-control\-setup\fR utility.
1106 This file is used by \fIunbound\-control\fR.
1107 .SS "Stub Zone Options"
1109 There may be multiple
1111 clauses. Each with a name: and zero or more hostnames or IP addresses.
1112 For the stub zone this list of nameservers is used. Class IN is assumed.
1113 The servers should be authority servers, not recursors; unbound performs
1114 the recursive processing itself for stub zones.
1116 The stub zone can be used to configure authoritative data to be used
1117 by the resolver that cannot be accessed using the public internet servers.
1118 This is useful for company\-local data or private zones. Setup an
1119 authoritative server on a different host (or different port). Enter a config
1120 entry for unbound with
1122 <ip address of host[@port]>.
1123 The unbound resolver can then access the data, without referring to the
1124 public internet for it.
1126 This setup allows DNSSEC signed zones to be served by that
1127 authoritative server, in which case a trusted key entry with the public key
1128 can be put in config, so that unbound can validate the data and set the AD
1129 bit on replies for the private zone (authoritative servers do not set the
1130 AD bit). This setup makes unbound capable of answering queries for the
1131 private zone, and can even set the AD bit ('authentic'), but the AA
1132 ('authoritative') bit is not set on these replies.
1134 Consider adding \fBserver:\fR statements for \fBdomain\-insecure:\fR and
1135 for \fBlocal\-zone:\fI name nodefault\fR for the zone if it is a locally
1136 served zone. The insecure clause stops DNSSEC from invalidating the
1137 zone. The local zone nodefault (or \fItransparent\fR) clause makes the
1138 (reverse\-) zone bypass unbound's filtering of RFC1918 zones.
1140 .B name: \fI<domain name>
1141 Name of the stub zone.
1143 .B stub\-host: \fI<domain name>
1144 Name of stub zone nameserver. Is itself resolved before it is used.
1146 .B stub\-addr: \fI<IP address>
1147 IP address of stub zone nameserver. Can be IP 4 or IP 6.
1148 To use a nondefault port for DNS communication append '@' with the port number.
1150 .B stub\-prime: \fI<yes or no>
1151 This option is by default off. If enabled it performs NS set priming,
1152 which is similar to root hints, where it starts using the list of nameservers
1153 currently published by the zone. Thus, if the hint list is slightly outdated,
1154 the resolver picks up a correct list online.
1156 .B stub\-first: \fI<yes or no>
1157 If enabled, a query is attempted without the stub clause if it fails.
1158 The data could not be retrieved and would have caused SERVFAIL because
1159 the servers are unreachable, instead it is tried without this clause.
1161 .SS "Forward Zone Options"
1163 There may be multiple
1165 clauses. Each with a \fBname:\fR and zero or more hostnames or IP
1166 addresses. For the forward zone this list of nameservers is used to
1167 forward the queries to. The servers listed as \fBforward\-host:\fR and
1168 \fBforward\-addr:\fR have to handle further recursion for the query. Thus,
1169 those servers are not authority servers, but are (just like unbound is)
1170 recursive servers too; unbound does not perform recursion itself for the
1171 forward zone, it lets the remote server do it. Class IN is assumed.
1172 A forward\-zone entry with name "." and a forward\-addr target will
1173 forward all queries to that other server (unless it can answer from
1176 .B name: \fI<domain name>
1177 Name of the forward zone.
1179 .B forward\-host: \fI<domain name>
1180 Name of server to forward to. Is itself resolved before it is used.
1182 .B forward\-addr: \fI<IP address>
1183 IP address of server to forward to. Can be IP 4 or IP 6.
1184 To use a nondefault port for DNS communication append '@' with the port number.
1186 .B forward\-first: \fI<yes or no>
1187 If enabled, a query is attempted without the forward clause if it fails.
1188 The data could not be retrieved and would have caused SERVFAIL because
1189 the servers are unreachable, instead it is tried without this clause.
1191 .SS "Python Module Options"
1195 clause gives the settings for the \fIpython\fR(1) script module. This module
1196 acts like the iterator and validator modules do, on queries and answers.
1197 To enable the script module it has to be compiled into the daemon,
1198 and the word "python" has to be put in the \fBmodule\-config:\fR option
1199 (usually first, or between the validator and iterator).
1201 .B python\-script: \fI<python file>\fR
1202 The script file to load.
1203 .SS "DNS64 Module Options"
1205 The dns64 module must be configured in the \fBmodule\-config:\fR "dns64
1206 validator iterator" directive and be compiled into the daemon to be
1207 enabled. These settings go in the \fBserver:\fR section.
1209 .B dns64\-prefix: \fI<IPv6 prefix>\fR
1210 This sets the DNS64 prefix to use to synthesize AAAA records with.
1211 It must be /96 or shorter. The default prefix is 64:ff9b::/96.
1213 .B dns64\-synthall: \fI<yes or no>\fR
1214 Debug option, default no. If enabled, synthesize all AAAA records
1215 despite the presence of actual AAAA records.
1216 .SH "MEMORY CONTROL EXAMPLE"
1217 In the example config settings below memory usage is reduced. Some service
1218 levels are lower, notable very large data and a high TCP load are no longer
1219 supported. Very large data and high TCP loads are exceptional for the DNS.
1220 DNSSEC validation is enabled, just add trust anchors.
1221 If you do not have to worry about programs using more than 3 Mb of memory,
1222 the below example is not for you. Use the defaults to receive full service,
1223 which on BSD\-32bit tops out at 30\-40 Mb after heavy usage.
1226 # example settings that reduce memory usage
1229 outgoing\-num\-tcp: 1 # this limits TCP service, uses less buffers.
1230 incoming\-num\-tcp: 1
1231 outgoing\-range: 60 # uses less memory, but less performance.
1232 msg\-buffer\-size: 8192 # note this limits service, 'no huge stuff'.
1233 msg\-cache\-size: 100k
1234 msg\-cache\-slabs: 1
1235 rrset\-cache\-size: 100k
1236 rrset\-cache\-slabs: 1
1237 infra\-cache\-numhosts: 200
1238 infra\-cache\-slabs: 1
1239 key\-cache\-size: 100k
1240 key\-cache\-slabs: 1
1241 neg\-cache\-size: 10k
1242 num\-queries\-per\-thread: 30
1243 target\-fetch\-policy: "2 1 0 0 0 0"
1244 harden\-large\-queries: "yes"
1245 harden\-short\-bufsize: "yes"
1249 .I @UNBOUND_RUN_DIR@
1250 default unbound working directory.
1252 .I @UNBOUND_CHROOT_DIR@
1258 unbound configuration file.
1260 .I @UNBOUND_PIDFILE@
1261 default unbound pidfile with process ID of the running daemon.
1264 unbound log file. default is to log to
1268 \fIunbound\-checkconf\fR(8).
1271 was written by NLnet Labs. Please see CREDITS file
1272 in the distribution for further details.
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