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21 unpublished primary having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 \fBforbid\-addr\fP [\fIip-address ...\fP]
178 Specifies the list of addresses that are forbidden as a nameserver
179 for a zone for which we are the primary - ie, the list of our old or
180 to-be-obsoleted slaves. The default is no such addresses.
182 \fBserverless\-glueless\fP \fIdomain ...\fP
183 Specifies a list of domains under which we do not expect to find any
184 nameservers without glue; for these zones it is OK to find glueless
186 Each domain listed names a complete subtree of the DNS, starting at
187 the named point. The default is
188 .BR "in\-addr.arpa ip6.arpa ip6.int" .
190 To avoid indefinitely long or even circularly glueless referrals
191 (which delay or prevent lookups) it is necessary for all sites to
192 effectively implement similar conventions; currently the author
193 believes that only the reverse lookup namespaces are conventionally
194 devoid of (glueless) nameservers, and therefore fine to provide
195 glueless referrals for. See GLUELESSNESS below.
197 \fBallow-\-indirect\-glue\fP \fInameserver-superdomain ...\fP
198 Specifies a list of domains under which we expect to find glueless
199 nameservers, with up to one layer of indirection.
200 For nameservers under these domains it is OK to to find glueless
201 referrals, but only when listed as a nameserver for a zone which is
202 not itself a subdomain of an \fBallow-indirect-glue\fR
203 \fInameserver-superdomain\fR.
205 This supports to common configuration style where DNS operator(s) set
206 up all of their nameservers with names within a small subsection of
207 the DNS (the portions under \fInameserver-superdomain\fRs), and
208 provide glueless referrals naming these nameservers for all other
209 zones. This provides at most one level of missing glue.
211 Note that if the DNS administrators collectively able to influence the
212 service for some zone (including the admins for its superzones, the
213 zones containing its nameservers, and their superzones and so forth)
214 are not in sufficiently close communication do not all agree on the
215 proper set of \fInameserver-superdomain\fR then they might still set
216 up circular glue and \fBchiark-named-conf\fR would not necessarily be
217 able to detect this even if it was run on every relevant nameserver.
219 \fBmail\-state\-dir\fP \fIdirectory\fP
222 for storing information about recent failures for mailing to zone
223 admins. See \-\-mail\-first et al. Old files in here should be
224 cleaned up periodically out of cron. There is no default.
226 \fBmail\-max\-warnfreq\fP \fIpercentage\fP
227 When \-\-mail\-final is used, a mail will be sent to all zones which
228 had warnings or errors more than
230 of the times \-\-mail\-* was used (since the last \-\-mail\-first).
233 .BR modifiers " " !*$@~? "] [\fIgroup\fP]"
234 Applies the specified zone style modifiers (see below) to subsequently
235 declared zones (until the next
237 directive), as if the modifiers specified were written out for
238 each zone. You must specify at least one character for the modifiers;
239 if you want to reset everything to the default, just say
241 If style modifiers specified in the zone directive
244 directive, those specified in the zone directive take effect.
246 may contain alphanumerics and underscores, and is used for the
250 \fBself\-addr\fP \fIip-address ...\fP
251 Specifies the list of addresses that this server may be known by in
252 A records. There is no default.
254 \fBoutput\fP \fIformat\fP \fIfilename\fP [\fIformat\fP \fIfilename ...\fP]
257 will be overwritten when
259 are used; its new contents will be configuration
260 directives for the zones which follow for the
261 nameserver in question. Currently the only
265 which indicates new-style BIND 8. If no zones follow, then each
266 file will still be overwritten, by an effectively empty file.
267 Default: if there is no
269 directive in the configuration then the default is to use
270 .BR bind8 " " chiark-conf-gen.bind8 ;
271 otherwise it is an error for there to be any zones in the
272 configuration before the first
276 \fBself\-ns\fP \fIfqdn ...\fP
277 Specifies the list of names that this server may be known by in NS
278 records. There is no default. Any trailing * is replaced by the name
279 of the zone being checked, so for example
281 before the zone example.com would mean to expect us to be listed as
285 \fBself\-soa\fP \fIfqdn ...\fP
286 Specifies the list of names that this server may be known by in
287 the ORIGIN field of SOA records. There is no default. Any trailing
288 * is replaced by the name of the zone, as for
293 .B self\-ns " and " self\-soa
294 with the same set of names.
296 \fBslave\-dir\fP \fIdirectory\fP [[\fIprefix\fP] \fIsuffix\fP]
297 Specifies the directory in which slave (published and stealth)
298 zonefiles should be placed. The default
301 .BR /var/cache/bind/chiark-slave .
303 .IR suffix " and " prefix
304 are empty; they also will be reset to these defaults by a
306 directive which does not specify them.
308 These directives specify one or more zones.
310 .BR primary [ !*$@~? "] \fIzone filename\fP"
311 Specifies that this server is supposed to be the primary nameserver
314 and that the zone data is to be found in
317 .BR primary\-dir [ !*$@~? "] \fIdirectory\fP[" / "\fIprefix\fP] [\fIsuffix\fP[" / \fIsubfile\fP]]
320 for files whose names start with
324 Each such file is taken to represent a zone file for which this server
325 is supposed to be the primary; the part of the filename between
326 .IR prefix " and " suffix
327 is the name of the zone.
331 is specified, then instead of looking for files, we search for
332 directories containing
334 directories which do not contain the subfile are simply skipped.
337 .IR directory [\fB/\fP prefix ]
338 exists as specified and is a directory then it is interpreted as
340 with an empty prefix; otherwise the final path component is assumed to
343 is specified then the default is
346 .BR published [ !*$@~? "] \fIzone origin\-addr\fP"
347 Specifies that this server is supposed to be a published slave
348 nameserver for the zone in question.
350 .BR stealth [ !*$@~? "] \fIzone server\-addr ...\fP"
351 Specifies that this server is supposed to be an unpublished secondary
352 (aka stealth secondary) for the zone in question.
353 .SS ZONE STYLE MODIFIERS
354 Each of the zone directives may optionally be followed by one or more
355 of the following characters (each at most once):
358 Reverses the meaning of all style modifiers after the
362 must appear in the modifier list. In this list, other modifiers which
363 default to `enabled' are described by describing the effect of their
364 inverse - see the description for
369 Indicates that the zone is unofficial, ie that it is not delegated as
370 part of the global Internet DNS and that no attempt should be made to
371 find the superzone and check delegations. Note that unofficial, local
372 zones should be created with caution. They should be in parts of the
373 namespace which are reserved for private use, or belong to the actual
377 Indicates that any mails should be sent about the zone to the
378 nameserver admin rather than to the zone SOA MNAME. This is the
379 default unless we are supposedly a published server for the zone.
382 Indicates that no mails should be sent about the zone to anyone.
385 Indicates that the zone's delegation is known to be glueless, and that
386 lack of glue should not be flagged. Not recommended - see the section
390 Indicates that the zone is known to be broken and no checks should be
391 carried out on it, unless the
396 \fBinclude\fP \fIfile\fP
399 as if it were included here.
402 Ends processing of this file; any data beyond this point is ignored.
404 chiark\-named\-conf makes the following checks:
406 Delegations: Each delegation from a server for the superzone should
407 contain the same set of nameservers. None of the delegations should
408 lack glue. The glue addresses should be the same in each delegation,
409 and agree with the local default nameserver.
411 Delegated servers: Each server mentioned in the delegation should have
412 the same SOA record (and obviously, should be authoritative).
414 All published nameservers - including delegated servers and servers
415 named in the zone's nameserver set: All nameservers for the zone
416 should supply the same list of nameservers for the zone, and none of
417 this authority information should be glueless. All the glue should
418 always give the same addresses.
420 Origin server's data: The set of nameservers in the origin server's
421 version of the zone should be a superset of those in the delegations.
423 Our zone configuration: For primary zones, the SOA origin should be
424 one of the names specified with
425 .BR self\-soa " (or " self ).
426 For published zones, the address should be that of the SOA origin.
427 For stealth zones, the address should be that of the SOA origin or one
428 of the published nameservers.
430 Glue is the name given for the addresses of nameservers which are
431 often supplied in a referral. In fact, it turns out that it is
432 important for the reliability and performance of the DNS that
433 referrals, in general, always come with glue.
435 Firstly, glueless referrals usually cause extra delays looking up
436 names. BIND 8, when it receives a completely glueless referral and
437 does not have the nameservers' addresses in its cache, will start
438 queries for the nameserver addresses; but it will throw the original
439 client's question away, so that when these queries arrive, it won't
440 restart the query from where it left off. This means that the client
441 won't get its answer until it retries, typically at least 1 second
442 later - longer if you have more than one nameserver listed. Worse, if
443 the nameserver to which the glueless referral points is itself under
444 another glueless referral, another retry will be required.
446 Even for better resolvers than BIND 8, long chains of glueless
447 referrals can cause performance and reliability problems, turning a
448 simple two or three query exchange into something needing more than a
451 Even worse, one might accidentally create a set of circularly glueless
454 .B example.com NS ns0.example.net.uk
456 .B example.com NS ns1.example.net.uk
458 .B example.net.uk NS ns0.example.com
460 .B example.net.uk NS ns1.example.com
462 Here it is impossible to look up anything in either example.com or
465 There are, as far as the author is aware, no generally agreed
466 conventions or standards for avoiding unreasonably long glueless
467 chains, or even circular glueless situations. The only way to
468 guarantee that things will work properly is therefore to always supply
471 However, the situation is further complicated by the fact that many
472 implementations (including BIND 8.2.3, and many registry systems),
473 will refuse to accept glue RRs for delegations in a parent zonefile
474 unless they are under the parent's zone apex. In these cases it can
475 be necessary to create names for the child's nameservers which are
476 underneath the child's apex, so that the glue records are both in the
477 parent's bailiwick and obviously necessary.
479 In the past, the `shared registry system' managing .com, .net and .org
480 did not allow a single IPv4 address to be used for more than one
481 nameserver name. However, at the time of writing (October 2002) this
482 problem seems to have been fixed, and the workaround I previously
483 recommended (creating a single name for your nameserver somewhere
484 in .com, .net or .org, and using that for all the delegations
485 from .com, .net and .org) should now be avoided.
487 Finally, a note about `reverse' zones, such as those in in-addr.arpa:
488 It does not seem at all common practice to create nameservers in
489 in-addr.arpa zones (ie, no NS RRs seem to point into in-addr.arpa,
490 even those for in-addr.arpa zones). Current practice seems to be to
491 always use nameservers for in-addr.arpa which are in the normal,
492 forward, address space. If everyone sticks to the rule of always
493 publishing nameservers names in the `main' part of the namespace, and
494 publishing glue for them, there is no chance of anything longer than a
495 1-step glueless chain might occur for a in-addr.arpa zone. It is
496 probably best to maintain this as the status quo, despite the
497 performance problem this implies for BIND 8 caches. This is what the
498 serverless\-glueless directive is for.
500 Dan Bernstein has some information and examples about this at
501 .UR http://cr.yp.to/djbdns/notes.html#gluelessness
502 http://cr.yp.to/djbdns/notes.html#gluelessness
504 but be warned that it is rather opinionated.
505 .SS GLUELESSNESS SUMMARY
507 I recommend that every nameserver should have its own name in every
508 forward zone that it serves. For example:
510 .B zone.example.com NS servus.ns.example.com
512 .B servus.ns.example.com A 127.0.0.2
514 .B 2.0.0.127.in-addr.arpa PTR servus.example.net
516 .B servus.example.net A 127.0.0.2
520 should not be used in the right hand side of NS records.
522 chiark\-named\-conf is supposed to be resistant to malicious data in
523 the DNS. It is not resistant to malicious data in its own options,
524 configuration file or environment. It is not supposed to read its
525 stdin, but is not guaranteed to be safe if stdin is dangerous.
527 Killing chiark-named-conf suddenly should be safe, even with
529 (though of course it may not complete its task if killed), provided
530 that only one invocation is made at once.
532 Slow remote nameservers will cause chiark-named-conf to take
537 All went well and there were no warnings.
540 There were warnings or errors.
543 .B /etc/bind/chiark-conf-gen.zones
544 Default input configuration file. (Override with
548 Default directory. (Override with
549 .BR -C " or " default\-dir .)
551 .IB dir /chiark-conf-gen.bind8
554 .B /var/cache/bind/chiark-slave
555 Default location for slave zones.
558 Setting variables used by
562 will affect the operation of chiark\-named\-conf.
563 Avoid messing with these if possible.
566 is used to find subprograms such as
567 .BR dig " and " adnshost .
569 The determination of the parent zone for each zone to be checked, and
570 its nameservers, is done simply using the system default nameserver.
572 The processing of output from
574 is not very reliable or robust, but this is mainly the fault of dig.
575 This can lead to somewhat unhelpful error reporting for lookup
578 .B chiark\-named\-conf
579 and this manpage were written by Ian Jackson
580 <ian@chiark.greenend.org.uk>. They are Copyright 2002 Ian Jackson.
582 chiark\-named\-conf and this manpage are free software; you can
583 redistribute it and/or modify it under the terms of the GNU General
584 Public License as published by the Free Software Foundation; either
585 version 2, or (at your option) any later version.
587 This is distributed in the hope that it will be useful, but WITHOUT ANY
588 WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
589 FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
592 You should have received a copy of the GNU General Public License along
593 with this program; if not, consult the Free Software Foundation's
594 website at www.fsf.org, or the GNU Project website at www.gnu.org.
~ian / chiark-utils.git / blob