1 .\" Hey, Emacs! This is an -*- nroff -*- source file.
2 .TH CHIARK\-NAMED\-CONF 8 "12th January 2002" "Greenend" "chiark utilities"
4 chiark\-named\-conf \- check and generate nameserver configuration
6 .BR chiark\-named\-conf " [\fIoptions\fP] " \-n | \-y | \-f
8 \fBchiark\-named\-conf\fP [\fIoptions\fP] \fIzone ...\fP
10 .B chiark\-named\-conf
11 is a tool for managing nameserver configurations and checking for
12 suspected DNS problems. Its main functions are to check that
13 delegations are appropriate and working, that secondary zones are
14 slaved from the right places, and to generate a configuration for
16 from its own input file.
18 By default, for each zone, in addition to any warnings, the output
19 lists the zone's configuration type. If the zone is checked, the
20 serial number at each of the nameservers is shown, with any
21 unpublished primary having
23 after the serial number.
28 .BR -n ", " -y ", or " -f
29 is supplied then chiark-named-conf will read its main configuration
30 file for the list of relevant zones. It will then check the
31 configuration and delegation for each zone
32 and/or generate and install a new configuration file for
36 Generate and install new nameserver config, as well as checking
37 configuration, for all listed zones.
40 Check configuration, for all listed zones, but
41 do not generate new nameserver config.
44 Generate and install new nameserver config, without doing any
45 configuration cross-checking. (Syntax errors in our input
46 configuration will still abort this operation.)
49 Do nothing: do no checks, and don't write a new config. This can be
50 used to get a list of the zones being processed.
52 .BR \-\-mail\-first " | " \-\-mail\-middle " | " \-\-mail\-final
53 Send mails to zone SOA MNAMEs reporting zones with problems. You must
54 call chiark\-named\-conf at least twice, once with \-\-mail\-first,
55 and later with \-\-mail\-final, and preferably with one or more calls
56 to \-\-mail\-middle in between. All three options carry out a check
57 and store the results; \-\-mail\-final also sends a mail to the zone
58 SOA MNAME or local administrator, if too many of the calls had errors
59 or warnings (calls before the most recent \-\-mail\-first being
62 .B \-mail\-final\-test
63 just like \-\-mail\-final except that it always sends mail to the
64 local server admin and never to remote zone contacts, adding
66 to the start of the To: field.
68 Alternatively, one or more zone names may be supplied as arguments, in
69 which case their delegations will be checked, and compared with the
70 data for that zone in the main configuration (if any). In this case
71 no new configuration file for the nameserver will be made.
73 .SS ADDITIONAL OPTIONS
76 Checks even zones known to be broken. Ie, ignores the
78 zone style modifier in the configuration.
80 .BR \-C | \-\-config " \fIconfig\-file\fP"
84 .BR /etc/bind/chiark-conf-gen.zones .
85 Also changes the default directory.
88 Enables debugging. Useful for debugging chiark\-named\-conf, but
89 probably not useful for debugging your DNS configuration. Repeat to
90 increase the debugging level. (Maximum is
93 .BR \-g | \-\-glueless
94 Do not warn about glueless referrals (strictly, makes the zone style
97 the default). Not recommended - see the section GLUELESSNESS, below.
100 Only checks for mistakes which are the responsibility of the local
101 administrator (to fix or get fixed). This means that for published
102 and stealth zones we only check that we're slaving from the right
103 place and that any names and addresses for ourself are right. For
104 primary zones all checks are still done. It is a mistake to specify
106 with foreign zones (zones supplied explictly on the command line but
107 not relevant to the local server); doing so produces a warning.
112 directive in the configuration file. The modifiers specified in the
113 directive are completely replaced by those specified in this command
114 line option. (Note that modifiers specified in per-zone directives
115 still override these per-group settings.) If more than one
117 directive specifies the same group, they are all affected.
119 directives which don't specify a group cannot be affected. It is an
120 error if the group does not appear in the config file. See ZONE STYLE
125 is used for zones which don't appear in the configuration file.
128 Suppress the usual report of the list of nameservers for each zone and
129 the serial number from each. When specified twice, do not print any
130 information except warnings.
133 When a problem is detected, warn for all sources of the same imperfect
134 data, rather than only the first we come across
136 .BR \-v | \-\-verbose
137 Print additional information about what is being checked, as we go
141 .B /etc/bind/chiark-conf-gen.zones
142 (or other file specified with the
144 option) contains a sequence of directives, one per line. Blank lines
145 are permitted. Leading and trailing whitespace on each line is
146 ignored. Comments are lines starting with
150 joins it to the next line, so that long directives can be split across
151 several physical lines.
152 .SS GENERAL DIRECTIVES
153 These directives specify general configuration details. They should
154 appear before directives specifying zones, as each will affect only
155 later zone directives.
157 \fBadmin\fP \fIemail\-address\fP
158 Specifies the email address of the local administrator. This is used
159 in the From: line of mails sent out, and will also receive copies of
160 the reports. There is no default.
162 \fBdefault\-dir\fP \fIdirectory\fP
165 be the default directory (which affects the interpretation of
166 relative filenames). The default is the directory containing
167 the main configuration file, ie
173 \fBforbid\-addr\fP [\fIip-address ...\fP]
174 Specifies the list of addresses that are forbidden as any nameserver
175 for any zone. The default is no such addresses.
177 \fBserverless\-glueless\fP \fIdomain ...\fP
178 Specifies a list of domains under which we do not expect to find any
179 nameservers; for these zones it is OK to find glueless referrals.
180 Each domain listed names a complete subtree of the DNS, starting at
181 the named point. The default is
182 .BR "in\-addr.arpa ip6.arpa ip6.int" .
184 To avoid indefinitely long or even circularly glueless referrals
185 (which delay or prevent lookups) it is necessary for all sites to
186 effectively implement similar conventions; currently the author
187 believes that only the reverse lookup namespaces are conventionally
188 devoid of nameservers, and therefore fine to provide glueless
189 referrals for. See GLUELESSNESS below.
191 \fBmail\-state\-dir\fP \fIdirectory\fP
194 for storing information about recent failures for mailing to zone
195 admins. See \-\-mail\-first et al. Old files in here should be
196 cleaned up periodically out of cron. There is no default.
198 \fBmail\-max\-warnfreq\fP \fIpercentage\fP
199 When \-\-mail\-final is used, a mail will be sent to all zones which
200 had warnings or errors more than
202 of the times \-\-mail\-* was used (since the last \-\-mail\-first).
205 .BR modifiers " " !*$@~? "] [\fIgroup\fP]"
206 Applies the specified zone style modifiers (see below) to subsequently
207 declared zones (until the next
209 directive), as if the modifiers specified were written out for
210 each zone. You must specify at least one character for the modifiers;
211 if you want to reset everything to the default, just say
213 If style modifiers specified in the zone directive
216 directive, those specified in the zone directive take effect.
218 may contain alphanumerics and underscores, and is used for the
222 \fBself\-addr\fP \fIip-address ...\fP
223 Specifies the list of addresses that this server may be known by in
224 A records. There is no default.
226 \fBoutput\fP \fIformat\fP \fIfilename\fP [\fIformat\fP \fIfilename ...\fP]
229 will be overwritten when
231 are used; its new contents will be configuration
232 directives for the zones which follow for the
233 nameserver in question. Currently the only
237 which indicates new-style BIND 8. If no zones follow, then each
238 file will still be overwritten, by an effectively empty file.
239 Default: if there is no
241 directive in the configuration then the default is to use
242 .BR bind8 " " chiark-conf-gen.bind8 ;
243 otherwise it is an error for there to be any zones in the
244 configuration before the first
248 \fBself\-ns\fP \fIfqdn ...\fP
249 Specifies the list of names that this server may be known by in NS
250 records. There is no default. Any trailing * is replaced by the name
251 of the zone being checked, so for example
253 before the zone example.com would mean to expect us to be listed as
257 \fBself\-soa\fP \fIfqdn ...\fP
258 Specifies the list of names that this server may be known by in
259 the ORIGIN field of SOA records. There is no default. Any trailing
260 * is replaced by the name of the zone, as for
265 .B self\-ns " and " self\-soa
266 with the same set of names.
268 \fBslave\-dir\fP \fIdirectory\fP [[\fIprefix\fP] \fIsuffix\fP]
269 Specifies the directory in which slave (published and stealth)
270 zonefiles should be placed. The default
273 .BR /var/cache/bind/chiark-slave .
275 .IR suffix " and " prefix
276 are empty; they also will be reset to these defaults by a
278 directive which does not specify them.
280 These directives specify one or more zones.
282 .BR primary [ !*$@~? "] \fIzone filename\fP"
283 Specifies that this server is supposed to be the primary nameserver
286 and that the zone data is to be found in
289 .BR primary\-dir [ !*$@~? "] \fIdirectory\fP[" / "\fIprefix\fP] [\fIsuffix\fP[" / \fIsubfile\fP]]
292 for files whose names start with
296 Each such file is taken to represent a zone file for which this server
297 is supposed to be the primary; the part of the filename between
298 .IR prefix " and " suffix
299 is the name of the zone.
303 is specified, then instead of looking for files, we search for
304 directories containing
306 directories which do not contain the subfile are simply skipped.
309 .IR directory [\fB/\fP prefix ]
310 exists as specified and is a directory then it is interpreted as
312 with an empty prefix; otherwise the final path component is assumed to
315 is specified then the default is
318 .BR published [ !*$@~? "] \fIzone origin\-addr\fP"
319 Specifies that this server is supposed to be a published slave
320 nameserver for the zone in question.
322 .BR stealth [ !*$@~? "] \fIzone server\-addr ...\fP"
323 Specifies that this server is supposed to be an unpublished secondary
324 (aka stealth secondary) for the zone in question.
325 .SS ZONE STYLE MODIFIERS
326 Each of the zone directives may optionally be followed by one or more
327 of the following characters (each at most once):
330 Reverses the meaning of all style modifiers after the
334 must appear in the modifier list. In this list, other modifiers which
335 default to `enabled' are described by describing the effect of their
336 inverse - see the description for
341 Indicates that the zone is unofficial, ie that it is not delegated as
342 part of the global Internet DNS and that no attempt should be made to
343 find the superzone and check delegations. Note that unofficial, local
344 zones should be created with caution. They should be in parts of the
345 namespace which are reserved for private use, or belong to the actual
349 Indicates that any mails should be sent about the zone to the
350 nameserver admin rather than to the zone SOA MNAME. This is the
351 default unless we are supposedly a published server for the zone.
354 Indicates that no mails should be sent about the zone to anyone.
357 Indicates that the zone's delegation is known to be glueless, and that
358 lack of glue should not be flagged. Not recommended - see the section
362 Indicates that the zone is known to be broken and no checks should be
363 carried out on it, unless the
368 \fBinclude\fP \fIfile\fP
371 as if it were included here.
374 Ends processing of this file; any data beyond this point is ignored.
376 chiark\-named\-conf makes the following checks:
378 Delegations: Each delegation from a server for the superzone should
379 contain the same set of nameservers. None of the delegations should
380 lack glue. The glue addresses should be the same in each delegation,
381 and agree with the local default nameserver.
383 Delegated servers: Each server mentioned in the delegation should have
384 the same SOA record (and obviously, should be authoritative).
386 All published nameservers - including delegated servers and servers
387 named in the zone's nameserver set: All nameservers for the zone
388 should supply the same list of nameservers for the zone, and none of
389 this authority information should be glueless. All the glue should
390 always give the same addresses.
392 Origin server's data: The set of nameservers in the origin server's
393 version of the zone should be a superset of those in the delegations.
395 Our zone configuration: For primary zones, the SOA origin should be
396 one of the names specified with
397 .BR self\-soa " (or " self ).
398 For published zones, the address should be that of the SOA origin.
399 For stealth zones, the address should be that of the SOA origin or one
400 of the published nameservers.
402 Glue is the name given for the addresses of nameservers which are
403 often supplied in a referral. In fact, it turns out that it is
404 important for the reliability and performance of the DNS that
405 referrals, in general, always come with glue.
407 Firstly, glueless referrals usually cause extra delays looking up
408 names. BIND 8, when it receives a completely glueless referral and
409 does not have the nameservers' addresses in its cache, will start
410 queries for the nameserver addresses; but it will throw the original
411 client's question away, so that when these queries arrive, it won't
412 restart the query from where it left off. This means that the client
413 won't get its answer until it retries, typically at least 1 second
414 later - longer if you have more than one nameserver listed. Worse, if
415 the nameserver to which the glueless referral points is itself under
416 another glueless referral, another retry will be required.
418 Even for better resolvers than BIND 8, long chains of glueless
419 referrals can cause performance and reliability problems, turning a
420 simple two or three query exchange into something needing more than a
423 Even worse, one might accidentally create a set of circularly glueless
426 .B example.com NS ns0.example.net.uk
428 .B example.com NS ns1.example.net.uk
430 .B example.net.uk NS ns0.example.com
432 .B example.net.uk NS ns1.example.com
434 Here it is impossible to look up anything in either example.com or
437 There are, as far as the author is aware, no generally agreed
438 conventions or standards for avoiding unreasonably long glueless
439 chains, or even circular glueless situations. The only way to
440 guarantee that things will work properly is therefore to always supply
443 However, the situation is further complicated by the fact that many
444 implementations (including BIND 8.2.3, and many registry systems),
445 will refuse to accept glue RRs for delegations in a parent zonefile
446 unless they are under the parent's zone apex. In these cases it can
447 be necessary to create names for the child's nameservers which are
448 underneath the child's apex, so that the glue records are both in the
449 parent's bailiwick and obviously necessary.
451 In the past, the `shared registry system' managing .com, .net and .org
452 did not allow a single IPv4 address to be used for more than one
453 nameserver name. However, at the time of writing (October 2002) this
454 problem seems to have been fixed, and the workaround I previously
455 recommended (creating a single name for your nameserver somewhere
456 in .com, .net or .org, and using that for all the delegations
457 from .com, .net and .org) should now be avoided.
459 Finally, a note about `reverse' zones, such as those in in-addr.arpa:
460 It does not seem at all common practice to create nameservers in
461 in-addr.arpa zones (ie, no NS RRs seem to point into in-addr.arpa,
462 even those for in-addr.arpa zones). Current practice seems to be to
463 always use nameservers for in-addr.arpa which are in the normal,
464 forward, address space. If everyone sticks to the rule of always
465 publishing nameservers names in the `main' part of the namespace, and
466 publishing glue for them, there is no chance of anything longer than a
467 1-step glueless chain might occur for a in-addr.arpa zone. It is
468 probably best to maintain this as the status quo, despite the
469 performance problem this implies for BIND 8 caches. This is what the
470 serverless\-glueless directive is for.
472 Dan Bernstein has some information and examples about this at
473 .UR http://cr.yp.to/djbdns/notes.html#gluelessness
474 http://cr.yp.to/djbdns/notes.html#gluelessness
476 but be warned that it is rather opinionated.
477 .SS GLUELESSNESS SUMMARY
479 I recommend that every nameserver should have its own name in every
480 forward zone that it serves. For example:
482 .B zone.example.com NS servus.ns.example.com
484 .B servus.ns.example.com A 127.0.0.2
486 .B 2.0.0.127.in-addr.arpa PTR servus.example.net
488 .B servus.example.net A 127.0.0.2
492 should not be used in the right hand side of NS records.
494 chiark\-named\-conf is supposed to be resistant to malicious data in
495 the DNS. It is not resistant to malicious data in its own options,
496 configuration file or environment. It is not supposed to read its
497 stdin, but is not guaranteed to be safe if stdin is dangerous.
499 Killing chiark-named-conf suddenly should be safe, even with
501 (though of course it may not complete its task if killed), provided
502 that only one invocation is made at once.
504 Slow remote nameservers will cause chiark-named-conf to take
509 All went well and there were no warnings.
512 There were warnings or errors.
515 .B /etc/bind/chiark-conf-gen.zones
516 Default input configuration file. (Override with
520 Default directory. (Override with
521 .BR -C " or " default\-dir .)
523 .IB dir /chiark-conf-gen.bind8
526 .B /var/cache/bind/chiark-slave
527 Default location for slave zones.
530 Setting variables used by
534 will affect the operation of chiark\-named\-conf.
535 Avoid messing with these if possible.
538 is used to find subprograms such as
539 .BR dig " and " adnshost .
541 The determination of the parent zone for each zone to be checked, and
542 its nameservers, is done simply using the system default nameserver.
544 The processing of output from
546 is not very reliable or robust, but this is mainly the fault of dig.
547 This can lead to somewhat unhelpful error reporting for lookup
550 .B chiark\-named\-conf
551 and this manpage were written by Ian Jackson
552 <ian@chiark.greenend.org.uk>. They are Copyright 2002 Ian Jackson.
554 chiark\-named\-conf and this manpage are free software; you can
555 redistribute it and/or modify it under the terms of the GNU General
556 Public License as published by the Free Software Foundation; either
557 version 2, or (at your option) any later version.
559 This is distributed in the hope that it will be useful, but WITHOUT ANY
560 WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
561 FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
564 You should have received a copy of the GNU General Public License along
565 with this program; if not, consult the Free Software Foundation's
566 website at www.fsf.org, or the GNU Project website at www.gnu.org.
~ian / chiark-utils.git / blob