.\" Hey, Emacs! This is an -*- nroff -*- source file. .TH CHIARK\-NAMED\-CONF 8 "12th January 2002" "Greenend" "chiark utilities" .SH NAME chiark\-named\-conf \- check and generate nameserver configuration .SH SYNOPSIS .BR chiark\-named\-conf " [\fIoptions\fP] " \-n | \-y | \-f .br \fBchiark\-named\-conf\fP [\fIoptions\fP] \fIzone ...\fP .SH DESCRIPTION .B chiark\-named\-conf is a tool for managing nameserver configurations and checking for suspected DNS problems. Its main functions are to check that delegations are appropriate and working, that secondary zones are slaved from the right places, and to generate a configuration for .BR BIND , from its own input file. By default, for each zone, in addition to any warnings, the output lists the zone's configuration type. If the zone is checked, the serial number at each of the nameservers is shown, with any unpublished primary having .B * after the serial number. .SH OPTIONS .SS MODE OPTIONS If one of the options .BR -n ", " -y ", or " -f is supplied then chiark-named-conf will read its main configuration file for the list of relevant zones. It will then check the configuration and delegation for each zone and/or generate and install a new configuration file for the nameserver: .TP .BR \-y | \-\-yes Generate and install new nameserver config, as well as checking configuration, for all listed zones. .TP .BR \-n | \-\-no Check configuration, for all listed zones, but do not generate new nameserver config. .TP .BR \-f | \-\-force Generate and install new nameserver config, without doing any configuration cross-checking. (Syntax errors in our input configuration will still abort this operation.) .LP Alternatively, one or more zone names may be supplied as arguments, in which case their delegations will be checked, and compared with the data for that zone in the main configuration (if any). In this case no new configuration file for the nameserver will be made. .SS ADDITIONAL OPTIONS .TP .BR \-A | \-\-all Checks even zones known to be broken. Ie, ignores the .B ? zone style modifier in the configuration. .TP .BR \-C | \-\-config " \fIconfig\-file\fP" Use .I config\-file instead of .BR /etc/bind/chiark-conf-gen.zones . Also changes the default directory. .TP .BR \-D Enables debugging. Useful for debugging chiark\-named\-conf, but probably not useful for debugging your DNS configuration. Repeat to increase the debugging level. (Maximum is .BR -DD .) .TP .BR \-g | \-\-glueless Do not warn about glueless referrals. Not recommended - see the section GLUELESSNESS, below. .TP .BR \-l | \-\-local Only checks for mistakes which are the responsibility of the local administrator (to fix or get fixed). This means that for published and stealth zones we only check that we're slaving from the right place and that any names and addresses for ourself are right. For primary zones all checks are still done. It is a mistake to specify .B \-l with foreign zones (zones supplied explictly on the command line but not relevant to the local server); doing so produces a warning. .TP .BR \-q | \-\-quiet Suppress the usual report of the list of nameservers for each zone and the serial number from each. When specified twice, do not print any information except warnings. .TP .BR \-r | \-\-repeat When a problem is detected, warn for all sources of the same imperfect data, rather than only the first we come across .TP .BR \-v | \-\-verbose Print additional information about what is being checked, as we go along. .SH USAGE The file .B /etc/bind/chiark-conf-gen.zones (or other file specified with the .B \-C option) contains a sequence of directives, one per line. Blank lines are permitted. Leading and trailing whitespace on each line is ignored. Comments are lines starting with .BR # . Ending a line with a .BR \\ joins it to the next line, so that long directives can be split across several physical lines. .SS GENERAL DIRECTIVES These directives specify general configuration details. They should appear before directives specifying zones, as each will affect only later zone directives. .TP \fBdefault\-dir\fP \fIdirectory\fP Makes .I directory be the default directory (which affects the interpretation of relative filenames). The default is the directory containing the main configuration file, ie .BR /etc/bind if no .B -C option is specified. .TP \fBforbid\-addr\fP [\fIip-address ...\fP] Specifies the list of addresses that are forbidden as any nameserver for any zone. The default is no such addresses. .TP \fBserverless\-glueless\fP \fIdomain ...\fP Specifies a list of domains under which we do not expect to find any nameservers; for these zones it is OK to find glueless referrals. Each domain listed names a complete subtree of the DNS, starting at the named point. The default is .BR "in\-addr.arpa ip6.arpa ip6.int" . To avoid indefinitely long or even circularly glueless referrals (which delay or prevent lookups) it is necessary for all sites to effectively implement similar conventions; currently the author believes that only the reverse lookup namespaces are conventionally devoid of nameservers, and therefore fine to provide glueless referrals for. See GLUELESSNESS below. .TP \fBoutput\fP \fIformat\fP \fIfilename\fP [\fIformat\fP \fIfilename ...\fP] Arranges that each .I filename will be overwritten when .BR -y " or " -f are used; its new contents will be configuration directives for the zones which follow for the nameserver in question. Currently the only .I format supported is .B bind8 which indicates new-style BIND 8. If no zones follow, then each file will still be overwritten, by an effectively empty file. Default: if there is no .B output directive in the configuration then the default is to use .BR bind8 " " chiark-conf-gen.bind8 ; otherwise it is an error for there to be any zones in the configuration before the first .B output directive. .TP \fBself\-addr\fP \fIip-address ...\fP Specifies the list of addresses that this server may be known by in A records. There is no default. .TP \fBself\-ns\fP \fIfqdn ...\fP Specifies the list of names that this server may be known by in NS records. There is no default. .TP \fBself\-soa\fP \fIfqdn ...\fP Specifies the list of names that this server may be known by in the ORIGIN field of SOA records. There is no default. .TP .BI self " fqdn ..." Equivalent to both .B self\-ns " and " self\-soa with the same set of names. .TP \fBslave\-dir\fP \fIdirectory\fP [[\fIprefix\fP] \fIsuffix\fP] Specifies the directory in which slave (published and stealth) zonefiles should be placed. The default .I directory is .BR /var/cache/bind/chiark-slave . The default .IR suffix " and " prefix are empty; they also will be reset to these defaults by a .B slave\-dir directive which does not specify them. .SS ZONE DIRECTIVES These directives specify one or more zones. .TP .BR primary [ * | ? "] \fIzone filename\fP" Specifies that this server is supposed to be the primary nameserver for .I zone and that the zone data is to be found in .IR filename . .TP .BR primary\-dir [ * | ? "] \fIdirectory\fP[" / "\fIprefix\fP] [\fIsuffix\fP[" / \fIsubfile\fP]] Search .I directory for files whose names start with .I prefix and end with .IR suffix . Each such file is taken to represent a zone file for which this server is supposed to be the primary; the part of the filename between .IR prefix " and " suffix is the name of the zone. If .BI / subfile is specified, then instead of looking for files, we search for directories containing .IR subfile ; directories which do not contain the subfile are simply skipped. If .IR directory [\fB/\fP prefix ] exists as specified and is a directory then it is interpreted as .I directory with an empty prefix; otherwise the final path component is assumed to be the prefix. If no .IB suffix / subfile is specified then the default is .BR _db . .TP .BR published [ * | ? "] \fIzone origin\-addr\fP" Specifies that this server is supposed to be a published slave nameserver for the zone in question. .TP .BR stealth [ * | ? "] \fIzone server\-addr ...\fP" Specifies that this server is supposed to be an unpublished secondary (aka stealth secondary) for the zone in question. .SS ZONE DIRECTIVE STYLE MODIFIERS Each of the zone directives may optionally be followed by one of the following characters: .TP .B * Indicates that the zone is unofficial, ie that it is not delegated as part of the global Internet DNS and that no attempt should be made to find the superzone and check delegations. Note that unofficial, local zones should be created with caution. They should be in parts of the namespace which are reserved for private use, or belong to the actual zone maintainer. .TP .B ? Indicates that the zone is known to be broken and no checks should be carried out on it, unless the .B \-A option is specified. .SS OTHER DIRECTIVES .TP \fBinclude\fP \fIfile\fP Reads .I file as if it were included here. .TP \fBend\fP Ends processing of this file; any data beyond this point is ignored. .SH CHECKS chiark\-named\-conf makes the following checks: Delegations: Each delegation from a server for the superzone should contain the same set of nameservers. None of the delegations should lack glue. The glue addresses should be the same in each delegation, and agree with the local default nameserver. Delegated servers: Each server mentioned in the delegation should have the same SOA record (and obviously, should be authoritative). All published nameservers - including delegated servers and servers named in the zone's nameserver set: All nameservers for the zone should supply the same list of nameservers for the zone, and none of this authority information should be glueless. All the glue should always give the same addresses. Origin server's data: The set of nameservers in the origin server's version of the zone should be a superset of those in the delegations. Our zone configuration: For primary zones, the SOA origin should be one of the names specified with .BR self\-soa " (or " self ). For published zones, the address should be that of the SOA origin. For stealth zones, the address should be that of the SOA origin or one of the published nameservers. .SH GLUELESSNESS Glue is the name given for the addresses of nameservers which are often supplied in a referral. In fact, it turns out that it is important for the reliability and performance of the DNS that referrals, in general, always come with glue. Firstly, glueless referrals usually cause extra delays looking up names. BIND 8, when it receives a completely glueless referral and does not have the nameservers' addresses in its cache, will start queries for the nameserver addresses; but it will throw the original client's question away, so that when these queries arrive, it won't restart the query from where it left off. This means that the client won't get its answer until it retries, typically at least 1 second later - longer if you have more than one nameserver listed. Worse, if the nameserver to which the glueless referral points is itself under another glueless referral, another retry will be required. Even for better resolvers than BIND 8, long chains of glueless referrals can cause performance and reliability problems, turning a simple two or three query exchange into something needing more than a dozen queries. Even worse, one might accidentally create a set of circularly glueless referrals such as .br .B example.com NS ns0.example.net.uk .br .B example.com NS ns1.example.net.uk .br .B example.net.uk NS ns0.example.com .br .B example.net.uk NS ns1.example.com .br Here it is impossible to look up anything in either example.com or example.net.uk. There are, as far as the author is aware, no generally agreed conventions or standards for avoiding unreasonably long glueless chains, or even circular glueless situations. The only way to guarantee that things will work properly is therefore to always supply glue. However, the situation is further complicated by the fact that many implementations (including BIND 8.2.3, and many registry systems), will refuse to accept glue RRs for delegations in a parent zonefile unless they are under the parent's zone apex. In these cases it can be necessary to create names for the child's nameservers which are underneath the child's apex, so that the glue records are both in the parent's bailiwick and obviously necessary. Even worse, the horrid `shared registry system' managing .com, .net and .org does not allow a single IPv4 address to be used for more than one nameserver name! It does, however, give out glue for any nameserver properly registered in the system. I therefore recommend that you create a single name for your nameserver somewhere in .com, .net or .org, and use that for all the delegations from .com, .net and .org. At the time of writing (January 2002) this seems to produce correct and glueful referrals. Finally, a note about `reverse' zones, such as those in in-addr.arpa: It does not seem at all common practice to create nameservers in in-addr.arpa zones (ie, no NS RRs seem to point into in-addr.arpa, even those for in-addr.arpa zones). Current practice seems to be to always use nameservers for in-addr.arpa which are in the normal, forward, address space. If everyone sticks to the rule of always publishing nameservers names in the `main' part of the namespace, and publishing glue for them, there is no chance of anything longer than a 1-step glueless chain might occur for a in-addr.arpa zone. It is probably best to maintain this as the status quo, despite the performance problem this implies for BIND 8 caches. This is what the serverless\-glueless directive is for. Dan Bernstein has some information and examples about this at .UR http://cr.yp.to/djbdns/notes.html#gluelessness http://cr.yp.to/djbdns/notes.html#gluelessness .UE but be warned that it is rather opinionated. .SH SECURITY chiark\-named\-conf is supposed to be resistant to malicious data in the DNS. It is not resistant to malicious data in its own options, configuration file or environment. It is not supposed to read its stdin, but is not guaranteed to be safe if stdin is dangerous. .LP Killing chiark-named-conf suddenly should be safe, even with .BR -y " or " -f (though of course it may not complete its task if killed), provided that only one invocation is made at once. .LP Slow remote nameservers will cause chiark-named-conf to take excessively long. .SH EXIT STATUS .TP .B 0 All went well and there were no warnings. .TP any other There were warnings or errors. .SH FILES .TP .B /etc/bind/chiark-conf-gen.zones Default input configuration file. (Override with .BR -C .) .TP .B /etc/bind Default directory. (Override with .BR -C " or " default\-dir .) .TP .IB dir /chiark-conf-gen.bind8 Default output file. .TP .B /var/cache/bind/chiark-slave Default location for slave zones. .SH ENVIRONMENT .LP Setting variables used by .BR dig (1) and .BR adnshost (1) will affect the operation of chiark\-named\-conf. Avoid messing with these if possible. .LP .B PATH is used to find subprograms such as .BR dig " and " adnshost . .SH BUGS The determination of the parent zone for each zone to be checked, and its nameservers, is done simply using the system default nameserver. The processing of output from .B dig is not very reliable or robust, but this is mainly the fault of dig. This can lead to somewhat unhelpful error reporting for lookup failures. .SH AUTHOR .B chiark\-named\-conf and this manpage were written by Ian Jackson . They are Copyright 2002 Ian Jackson. chiark\-named\-conf and this manpage are free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2, or (at your option) any later version. This is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.