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First draft of resolver(5) man page
This commit is contained in:
Jim Reid
parent
69f2a57302
commit
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doc/man/bin/resolver.5
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215
doc/man/bin/resolver.5
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.\" Copyright (C) @YEARS@ Internet Software Consortium.
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.\"
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.\" Permission to use, copy, modify, and distribute this software for any
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|
.\" purpose with or without fee is hereby granted, provided that the above
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||||||
|
.\" copyright notice and this permission notice appear in all copies.
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||||||
|
.\"
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||||||
|
.\" THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM
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||||||
|
.\" DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL
|
||||||
|
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL
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||||||
|
.\" INTERNET SOFTWARE CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT,
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||||||
|
.\" INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING
|
||||||
|
.\" FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,
|
||||||
|
.\" NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION
|
||||||
|
.\" WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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.\"
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.\" $Id: resolver.5,v 1.1 2000/09/03 20:45:58 jim Exp $
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.\"
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.Dd Jun 30, 2000
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.Dt RESOLVER 5
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.Os BIND9 9
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.ds vT BIND9 Programmer's Manual
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.Sh NAME
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.Nm resolver
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.Nd resolver configuration file
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.Sh SYNOPSIS
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.Pa /etc/resolv.conf
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.Sh DESCRIPTION
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||||||
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The
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.Nm resolver
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and
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.Nm "BIND9 lightwreight resolver"
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|
are sets of routines in the C library and BIND9 library respectively
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|
that provide access to the Internet Domain Name System.
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|
The resolver configuration file,
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|
.Pa /etc/resolv.conf ,
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|
is normally gets read
|
||||||
|
by the resolver and lightweight resolver
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|
routines to initialise low-level resolver data structures the first time
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||||||
|
that a process invokes those routines.
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||||||
|
The file contains a list of
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||||||
|
keywords with values that provide various types of
|
||||||
|
information, such as the IP addresses of the servers that should be
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||||||
|
used when making lookup requests.
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.Pp
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||||||
|
Each keyword and value must appear on a single line.
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|
The value follows the keyword, separated by white space.
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||||||
|
The hash character '#' or semi-colon ';' introduce comments.
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||||||
|
Anything from either of these characters to the end of the line
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||||||
|
is treated as a comment and ignored.
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|
.\" XXXJR - Don't think the next para is relevant. Not every host will run
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.\" a name server or lightweight resolver. Those that don't will need
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.\" a resolv.conf so they can send their lookups somewhere sensible.
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.\".Pp
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.\"On a normally configured system, this file should not be necessary.
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.\"The only name server to be queried will be on the local machine,
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.\"the domain name is determined from the host name,
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|
.\"and the domain search path is constructed from the domain name.
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|
.Pp
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||||||
|
The available configuration directives are:
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|
.Bl -tag -width "nameserver"
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.It Li nameserver
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|
Internet address of a name server that the resolver should query.
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|
The IP address of the server can be supplied in the usual notation:
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||||||
|
either in dotted-decimal form for an IPv4 addess or in double colon
|
||||||
|
form described in RFC1884 for an IPv6 address.
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|
Up to three nameserver directives can be listed.
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|
See
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|
.Dv LWRES_CONFMAXNAMESERVERS
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in
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.Pa <lwres/lwres.h> .
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If more than
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.Dv LWRES_CONFMAXNAMESERVERS
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nameserver directives are present in the file,
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only the first three are used.
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Any others are ignored.
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.Pp
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|
When there are multiple servers, the resolver
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library queries them in the order listed.
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|
If no
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.Li nameserver
|
||||||
|
entries are present, the default is to attempt to use the name server or
|
||||||
|
lightweight resolver daemon on the local machine.
|
||||||
|
The algorithm used is to try a server, and if the query times out,
|
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|
try the next, until out of name servers,
|
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|
then repeat trying all the name servers
|
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|
until a maximum number of retries are made.
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|
.It Li domain
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|
Local domain name.
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|
Most queries for names within this domain can use short names
|
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|
relative to the local domain.
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|
When no
|
||||||
|
.Li domain
|
||||||
|
entry is present, the domain is determined from the local host name returned by
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|
.Xr gethostname 2 ;
|
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|
the domain part is taken to be everything after the first
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|
.Sq \&. .
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|
Finally, if the host name does not contain a domain part, the root
|
||||||
|
domain is assumed.
|
||||||
|
.It Li search
|
||||||
|
Search list for host-name lookup.
|
||||||
|
The search list is normally determined from the local domain name;
|
||||||
|
by default, it contains only the local domain name.
|
||||||
|
This may be changed by listing the desired domain search path
|
||||||
|
following the
|
||||||
|
.Li search
|
||||||
|
keyword with spaces or tabs separating the names.
|
||||||
|
Most resolver
|
||||||
|
queries will be attempted using each component
|
||||||
|
of the search path in turn until a match is found.
|
||||||
|
Note that this process may be slow and will generate a lot of network
|
||||||
|
traffic if the servers for the listed domains are not local,
|
||||||
|
and that queries will time out if no server is available
|
||||||
|
for one of the domains.
|
||||||
|
.Pp
|
||||||
|
The search list is currently limited to eight domains
|
||||||
|
with a total of 256 characters.
|
||||||
|
See
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|
.Dv LWRES_CONFMAXSEARCH
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and
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.Dv LWRES_CONFMAXLINELEN
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in
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.Pa lwres/lwres.h .
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|
.It Li sortlist
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|
Allows addresses returned by gethostbyname to be sorted.
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|
A
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|
.Li sortlist
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||||||
|
is specified by IP address netmask pairs.
|
||||||
|
The netmask is optional and defaults to the natural netmask of the net.
|
||||||
|
The IP address and optional network pairs are separated by slashes.
|
||||||
|
Up to 10 pairs may be specified.
|
||||||
|
For example:
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|
.Bd -literal -offset indent
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|
sortlist 130.155.160.0/255.255.240.0 130.155.0.0
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|
.Ed
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|
.It Li options
|
||||||
|
Allows certain internal
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||||||
|
.Nm resolver
|
||||||
|
variables to be modified.
|
||||||
|
The syntax is
|
||||||
|
.D1 Li options Ar option ...
|
||||||
|
where
|
||||||
|
.Ar option
|
||||||
|
is one of the following:
|
||||||
|
.Bl -tag -width "no_tld_query"
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|
.It Li ndots: Ns Ar n
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|
sets a threshold for the number of dots which
|
||||||
|
must appear in a name given to
|
||||||
|
.Fn res_query
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||||||
|
(see
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|
.Xr resolver 3 )
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||||||
|
before an
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||||||
|
.Em initial absolute query
|
||||||
|
will be made.
|
||||||
|
The default for
|
||||||
|
.Ar n
|
||||||
|
is
|
||||||
|
.Dq 1 ,
|
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|
meaning that if there are
|
||||||
|
.Em any
|
||||||
|
dots in a name, the name will be tried first as an absolute name before any
|
||||||
|
.Em search list
|
||||||
|
elements are appended to it.
|
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|
Acceptable values of
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|
.Ar n
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|
are between 0 and 255 inclusive.
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|
.It debug
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|
enables debugging traces for the resolver
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|
XXXJR if anything actually looked at
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|
.Dv confdata->resdebug .
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|
At present the option is just recognised but not used by
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|
the BIND9 implementation.
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|
.It no_tld_query
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|
tells the resolver not to attempt to resolve a
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|
top level domain name, i.e. a name containing no dots.
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|
Use of this option does not prevent the resolver from obeying the
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|
standard
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|
.Ar domain
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||||||
|
and
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|
.Ar search
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||||||
|
rules with the given name.
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|
XXXJR At present this option is recognised but is otherwise unused
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|
in BIND9.
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|
.It missing
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|
XXXJR what about the other BIND8 resolver options like rotate and
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|
timeout? Shouldn't these be provided for backwards compatibility?
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|
.El
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||||||
|
.El
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||||||
|
.Pp
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||||||
|
The
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|
.Li domain
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||||||
|
and
|
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|
.Li search
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||||||
|
keywords are mutually exclusive.
|
||||||
|
If more than one instance of these keywords is present,
|
||||||
|
the last instance wins.
|
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|
.Sh FILES
|
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|
.Pa /etc/resolv.conf
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|
.Pa <lwres/lwres.h>
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|
.Sh SEE ALSO
|
||||||
|
.Xr gethostbyname 3 ,
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|
.Xr lwres_config 3 ,
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|
.Xr lwres 3 ,
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|
.Xr resolver 3 ,
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|
.Xr hostname 7 ,
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|
.Xr lwresd 8 ,
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|
.Xr named 8 ,
|
||||||
|
"BIND9 Administrators Manual".
|
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|
.Sh BUGS
|
||||||
|
Unrecognised directives and syntax errors in
|
||||||
|
.Pa /etc/resolv.conf
|
||||||
|
are usually silently ignored, though
|
||||||
|
.Er LWRES_R_FAILURE
|
||||||
|
can be returned by the lightweight resolver functions described in
|
||||||
|
.Xr lwres_config 3
|
||||||
|
which parse this file.
|
||||||
215
doc/man/lwres/resolver.5
Normal file
215
doc/man/lwres/resolver.5
Normal file
@ -0,0 +1,215 @@
|
|||||||
|
.\" Copyright (C) @YEARS@ Internet Software Consortium.
|
||||||
|
.\"
|
||||||
|
.\" Permission to use, copy, modify, and distribute this software for any
|
||||||
|
.\" purpose with or without fee is hereby granted, provided that the above
|
||||||
|
.\" copyright notice and this permission notice appear in all copies.
|
||||||
|
.\"
|
||||||
|
.\" THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM
|
||||||
|
.\" DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL
|
||||||
|
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL
|
||||||
|
.\" INTERNET SOFTWARE CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT,
|
||||||
|
.\" INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING
|
||||||
|
.\" FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,
|
||||||
|
.\" NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION
|
||||||
|
.\" WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
|
||||||
|
.\"
|
||||||
|
.\" $Id: resolver.5,v 1.1 2000/09/03 20:45:58 jim Exp $
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|
.\"
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||||||
|
.Dd Jun 30, 2000
|
||||||
|
.Dt RESOLVER 5
|
||||||
|
.Os BIND9 9
|
||||||
|
.ds vT BIND9 Programmer's Manual
|
||||||
|
.Sh NAME
|
||||||
|
.Nm resolver
|
||||||
|
.Nd resolver configuration file
|
||||||
|
.Sh SYNOPSIS
|
||||||
|
.Pa /etc/resolv.conf
|
||||||
|
.Sh DESCRIPTION
|
||||||
|
The
|
||||||
|
.Nm resolver
|
||||||
|
and
|
||||||
|
.Nm "BIND9 lightwreight resolver"
|
||||||
|
are sets of routines in the C library and BIND9 library respectively
|
||||||
|
that provide access to the Internet Domain Name System.
|
||||||
|
The resolver configuration file,
|
||||||
|
.Pa /etc/resolv.conf ,
|
||||||
|
is normally gets read
|
||||||
|
by the resolver and lightweight resolver
|
||||||
|
routines to initialise low-level resolver data structures the first time
|
||||||
|
that a process invokes those routines.
|
||||||
|
The file contains a list of
|
||||||
|
keywords with values that provide various types of
|
||||||
|
information, such as the IP addresses of the servers that should be
|
||||||
|
used when making lookup requests.
|
||||||
|
.Pp
|
||||||
|
Each keyword and value must appear on a single line.
|
||||||
|
The value follows the keyword, separated by white space.
|
||||||
|
The hash character '#' or semi-colon ';' introduce comments.
|
||||||
|
Anything from either of these characters to the end of the line
|
||||||
|
is treated as a comment and ignored.
|
||||||
|
.\" XXXJR - Don't think the next para is relevant. Not every host will run
|
||||||
|
.\" a name server or lightweight resolver. Those that don't will need
|
||||||
|
.\" a resolv.conf so they can send their lookups somewhere sensible.
|
||||||
|
.\".Pp
|
||||||
|
.\"On a normally configured system, this file should not be necessary.
|
||||||
|
.\"The only name server to be queried will be on the local machine,
|
||||||
|
.\"the domain name is determined from the host name,
|
||||||
|
.\"and the domain search path is constructed from the domain name.
|
||||||
|
.Pp
|
||||||
|
The available configuration directives are:
|
||||||
|
.Bl -tag -width "nameserver"
|
||||||
|
.It Li nameserver
|
||||||
|
Internet address of a name server that the resolver should query.
|
||||||
|
The IP address of the server can be supplied in the usual notation:
|
||||||
|
either in dotted-decimal form for an IPv4 addess or in double colon
|
||||||
|
form described in RFC1884 for an IPv6 address.
|
||||||
|
Up to three nameserver directives can be listed.
|
||||||
|
See
|
||||||
|
.Dv LWRES_CONFMAXNAMESERVERS
|
||||||
|
in
|
||||||
|
.Pa <lwres/lwres.h> .
|
||||||
|
If more than
|
||||||
|
.Dv LWRES_CONFMAXNAMESERVERS
|
||||||
|
nameserver directives are present in the file,
|
||||||
|
only the first three are used.
|
||||||
|
Any others are ignored.
|
||||||
|
.Pp
|
||||||
|
When there are multiple servers, the resolver
|
||||||
|
library queries them in the order listed.
|
||||||
|
If no
|
||||||
|
.Li nameserver
|
||||||
|
entries are present, the default is to attempt to use the name server or
|
||||||
|
lightweight resolver daemon on the local machine.
|
||||||
|
The algorithm used is to try a server, and if the query times out,
|
||||||
|
try the next, until out of name servers,
|
||||||
|
then repeat trying all the name servers
|
||||||
|
until a maximum number of retries are made.
|
||||||
|
.It Li domain
|
||||||
|
Local domain name.
|
||||||
|
Most queries for names within this domain can use short names
|
||||||
|
relative to the local domain.
|
||||||
|
When no
|
||||||
|
.Li domain
|
||||||
|
entry is present, the domain is determined from the local host name returned by
|
||||||
|
.Xr gethostname 2 ;
|
||||||
|
the domain part is taken to be everything after the first
|
||||||
|
.Sq \&. .
|
||||||
|
Finally, if the host name does not contain a domain part, the root
|
||||||
|
domain is assumed.
|
||||||
|
.It Li search
|
||||||
|
Search list for host-name lookup.
|
||||||
|
The search list is normally determined from the local domain name;
|
||||||
|
by default, it contains only the local domain name.
|
||||||
|
This may be changed by listing the desired domain search path
|
||||||
|
following the
|
||||||
|
.Li search
|
||||||
|
keyword with spaces or tabs separating the names.
|
||||||
|
Most resolver
|
||||||
|
queries will be attempted using each component
|
||||||
|
of the search path in turn until a match is found.
|
||||||
|
Note that this process may be slow and will generate a lot of network
|
||||||
|
traffic if the servers for the listed domains are not local,
|
||||||
|
and that queries will time out if no server is available
|
||||||
|
for one of the domains.
|
||||||
|
.Pp
|
||||||
|
The search list is currently limited to eight domains
|
||||||
|
with a total of 256 characters.
|
||||||
|
See
|
||||||
|
.Dv LWRES_CONFMAXSEARCH
|
||||||
|
and
|
||||||
|
.Dv LWRES_CONFMAXLINELEN
|
||||||
|
in
|
||||||
|
.Pa lwres/lwres.h .
|
||||||
|
.It Li sortlist
|
||||||
|
Allows addresses returned by gethostbyname to be sorted.
|
||||||
|
A
|
||||||
|
.Li sortlist
|
||||||
|
is specified by IP address netmask pairs.
|
||||||
|
The netmask is optional and defaults to the natural netmask of the net.
|
||||||
|
The IP address and optional network pairs are separated by slashes.
|
||||||
|
Up to 10 pairs may be specified.
|
||||||
|
For example:
|
||||||
|
.Bd -literal -offset indent
|
||||||
|
sortlist 130.155.160.0/255.255.240.0 130.155.0.0
|
||||||
|
.Ed
|
||||||
|
.It Li options
|
||||||
|
Allows certain internal
|
||||||
|
.Nm resolver
|
||||||
|
variables to be modified.
|
||||||
|
The syntax is
|
||||||
|
.D1 Li options Ar option ...
|
||||||
|
where
|
||||||
|
.Ar option
|
||||||
|
is one of the following:
|
||||||
|
.Bl -tag -width "no_tld_query"
|
||||||
|
.It Li ndots: Ns Ar n
|
||||||
|
sets a threshold for the number of dots which
|
||||||
|
must appear in a name given to
|
||||||
|
.Fn res_query
|
||||||
|
(see
|
||||||
|
.Xr resolver 3 )
|
||||||
|
before an
|
||||||
|
.Em initial absolute query
|
||||||
|
will be made.
|
||||||
|
The default for
|
||||||
|
.Ar n
|
||||||
|
is
|
||||||
|
.Dq 1 ,
|
||||||
|
meaning that if there are
|
||||||
|
.Em any
|
||||||
|
dots in a name, the name will be tried first as an absolute name before any
|
||||||
|
.Em search list
|
||||||
|
elements are appended to it.
|
||||||
|
Acceptable values of
|
||||||
|
.Ar n
|
||||||
|
are between 0 and 255 inclusive.
|
||||||
|
.It debug
|
||||||
|
enables debugging traces for the resolver
|
||||||
|
XXXJR if anything actually looked at
|
||||||
|
.Dv confdata->resdebug .
|
||||||
|
At present the option is just recognised but not used by
|
||||||
|
the BIND9 implementation.
|
||||||
|
.It no_tld_query
|
||||||
|
tells the resolver not to attempt to resolve a
|
||||||
|
top level domain name, i.e. a name containing no dots.
|
||||||
|
Use of this option does not prevent the resolver from obeying the
|
||||||
|
standard
|
||||||
|
.Ar domain
|
||||||
|
and
|
||||||
|
.Ar search
|
||||||
|
rules with the given name.
|
||||||
|
XXXJR At present this option is recognised but is otherwise unused
|
||||||
|
in BIND9.
|
||||||
|
.It missing
|
||||||
|
XXXJR what about the other BIND8 resolver options like rotate and
|
||||||
|
timeout? Shouldn't these be provided for backwards compatibility?
|
||||||
|
.El
|
||||||
|
.El
|
||||||
|
.Pp
|
||||||
|
The
|
||||||
|
.Li domain
|
||||||
|
and
|
||||||
|
.Li search
|
||||||
|
keywords are mutually exclusive.
|
||||||
|
If more than one instance of these keywords is present,
|
||||||
|
the last instance wins.
|
||||||
|
.Sh FILES
|
||||||
|
.Pa /etc/resolv.conf
|
||||||
|
.Pa <lwres/lwres.h>
|
||||||
|
.Sh SEE ALSO
|
||||||
|
.Xr gethostbyname 3 ,
|
||||||
|
.Xr lwres_config 3 ,
|
||||||
|
.Xr lwres 3 ,
|
||||||
|
.Xr resolver 3 ,
|
||||||
|
.Xr hostname 7 ,
|
||||||
|
.Xr lwresd 8 ,
|
||||||
|
.Xr named 8 ,
|
||||||
|
"BIND9 Administrators Manual".
|
||||||
|
.Sh BUGS
|
||||||
|
Unrecognised directives and syntax errors in
|
||||||
|
.Pa /etc/resolv.conf
|
||||||
|
are usually silently ignored, though
|
||||||
|
.Er LWRES_R_FAILURE
|
||||||
|
can be returned by the lightweight resolver functions described in
|
||||||
|
.Xr lwres_config 3
|
||||||
|
which parse this file.
|
||||||
215
lib/lwres/man/resolver.5
Normal file
215
lib/lwres/man/resolver.5
Normal file
@ -0,0 +1,215 @@
|
|||||||
|
.\" Copyright (C) @YEARS@ Internet Software Consortium.
|
||||||
|
.\"
|
||||||
|
.\" Permission to use, copy, modify, and distribute this software for any
|
||||||
|
.\" purpose with or without fee is hereby granted, provided that the above
|
||||||
|
.\" copyright notice and this permission notice appear in all copies.
|
||||||
|
.\"
|
||||||
|
.\" THE SOFTWARE IS PROVIDED "AS IS" AND INTERNET SOFTWARE CONSORTIUM
|
||||||
|
.\" DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL
|
||||||
|
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL
|
||||||
|
.\" INTERNET SOFTWARE CONSORTIUM BE LIABLE FOR ANY SPECIAL, DIRECT,
|
||||||
|
.\" INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING
|
||||||
|
.\" FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,
|
||||||
|
.\" NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION
|
||||||
|
.\" WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
|
||||||
|
.\"
|
||||||
|
.\" $Id: resolver.5,v 1.1 2000/09/03 20:45:58 jim Exp $
|
||||||
|
.\"
|
||||||
|
.Dd Jun 30, 2000
|
||||||
|
.Dt RESOLVER 5
|
||||||
|
.Os BIND9 9
|
||||||
|
.ds vT BIND9 Programmer's Manual
|
||||||
|
.Sh NAME
|
||||||
|
.Nm resolver
|
||||||
|
.Nd resolver configuration file
|
||||||
|
.Sh SYNOPSIS
|
||||||
|
.Pa /etc/resolv.conf
|
||||||
|
.Sh DESCRIPTION
|
||||||
|
The
|
||||||
|
.Nm resolver
|
||||||
|
and
|
||||||
|
.Nm "BIND9 lightwreight resolver"
|
||||||
|
are sets of routines in the C library and BIND9 library respectively
|
||||||
|
that provide access to the Internet Domain Name System.
|
||||||
|
The resolver configuration file,
|
||||||
|
.Pa /etc/resolv.conf ,
|
||||||
|
is normally gets read
|
||||||
|
by the resolver and lightweight resolver
|
||||||
|
routines to initialise low-level resolver data structures the first time
|
||||||
|
that a process invokes those routines.
|
||||||
|
The file contains a list of
|
||||||
|
keywords with values that provide various types of
|
||||||
|
information, such as the IP addresses of the servers that should be
|
||||||
|
used when making lookup requests.
|
||||||
|
.Pp
|
||||||
|
Each keyword and value must appear on a single line.
|
||||||
|
The value follows the keyword, separated by white space.
|
||||||
|
The hash character '#' or semi-colon ';' introduce comments.
|
||||||
|
Anything from either of these characters to the end of the line
|
||||||
|
is treated as a comment and ignored.
|
||||||
|
.\" XXXJR - Don't think the next para is relevant. Not every host will run
|
||||||
|
.\" a name server or lightweight resolver. Those that don't will need
|
||||||
|
.\" a resolv.conf so they can send their lookups somewhere sensible.
|
||||||
|
.\".Pp
|
||||||
|
.\"On a normally configured system, this file should not be necessary.
|
||||||
|
.\"The only name server to be queried will be on the local machine,
|
||||||
|
.\"the domain name is determined from the host name,
|
||||||
|
.\"and the domain search path is constructed from the domain name.
|
||||||
|
.Pp
|
||||||
|
The available configuration directives are:
|
||||||
|
.Bl -tag -width "nameserver"
|
||||||
|
.It Li nameserver
|
||||||
|
Internet address of a name server that the resolver should query.
|
||||||
|
The IP address of the server can be supplied in the usual notation:
|
||||||
|
either in dotted-decimal form for an IPv4 addess or in double colon
|
||||||
|
form described in RFC1884 for an IPv6 address.
|
||||||
|
Up to three nameserver directives can be listed.
|
||||||
|
See
|
||||||
|
.Dv LWRES_CONFMAXNAMESERVERS
|
||||||
|
in
|
||||||
|
.Pa <lwres/lwres.h> .
|
||||||
|
If more than
|
||||||
|
.Dv LWRES_CONFMAXNAMESERVERS
|
||||||
|
nameserver directives are present in the file,
|
||||||
|
only the first three are used.
|
||||||
|
Any others are ignored.
|
||||||
|
.Pp
|
||||||
|
When there are multiple servers, the resolver
|
||||||
|
library queries them in the order listed.
|
||||||
|
If no
|
||||||
|
.Li nameserver
|
||||||
|
entries are present, the default is to attempt to use the name server or
|
||||||
|
lightweight resolver daemon on the local machine.
|
||||||
|
The algorithm used is to try a server, and if the query times out,
|
||||||
|
try the next, until out of name servers,
|
||||||
|
then repeat trying all the name servers
|
||||||
|
until a maximum number of retries are made.
|
||||||
|
.It Li domain
|
||||||
|
Local domain name.
|
||||||
|
Most queries for names within this domain can use short names
|
||||||
|
relative to the local domain.
|
||||||
|
When no
|
||||||
|
.Li domain
|
||||||
|
entry is present, the domain is determined from the local host name returned by
|
||||||
|
.Xr gethostname 2 ;
|
||||||
|
the domain part is taken to be everything after the first
|
||||||
|
.Sq \&. .
|
||||||
|
Finally, if the host name does not contain a domain part, the root
|
||||||
|
domain is assumed.
|
||||||
|
.It Li search
|
||||||
|
Search list for host-name lookup.
|
||||||
|
The search list is normally determined from the local domain name;
|
||||||
|
by default, it contains only the local domain name.
|
||||||
|
This may be changed by listing the desired domain search path
|
||||||
|
following the
|
||||||
|
.Li search
|
||||||
|
keyword with spaces or tabs separating the names.
|
||||||
|
Most resolver
|
||||||
|
queries will be attempted using each component
|
||||||
|
of the search path in turn until a match is found.
|
||||||
|
Note that this process may be slow and will generate a lot of network
|
||||||
|
traffic if the servers for the listed domains are not local,
|
||||||
|
and that queries will time out if no server is available
|
||||||
|
for one of the domains.
|
||||||
|
.Pp
|
||||||
|
The search list is currently limited to eight domains
|
||||||
|
with a total of 256 characters.
|
||||||
|
See
|
||||||
|
.Dv LWRES_CONFMAXSEARCH
|
||||||
|
and
|
||||||
|
.Dv LWRES_CONFMAXLINELEN
|
||||||
|
in
|
||||||
|
.Pa lwres/lwres.h .
|
||||||
|
.It Li sortlist
|
||||||
|
Allows addresses returned by gethostbyname to be sorted.
|
||||||
|
A
|
||||||
|
.Li sortlist
|
||||||
|
is specified by IP address netmask pairs.
|
||||||
|
The netmask is optional and defaults to the natural netmask of the net.
|
||||||
|
The IP address and optional network pairs are separated by slashes.
|
||||||
|
Up to 10 pairs may be specified.
|
||||||
|
For example:
|
||||||
|
.Bd -literal -offset indent
|
||||||
|
sortlist 130.155.160.0/255.255.240.0 130.155.0.0
|
||||||
|
.Ed
|
||||||
|
.It Li options
|
||||||
|
Allows certain internal
|
||||||
|
.Nm resolver
|
||||||
|
variables to be modified.
|
||||||
|
The syntax is
|
||||||
|
.D1 Li options Ar option ...
|
||||||
|
where
|
||||||
|
.Ar option
|
||||||
|
is one of the following:
|
||||||
|
.Bl -tag -width "no_tld_query"
|
||||||
|
.It Li ndots: Ns Ar n
|
||||||
|
sets a threshold for the number of dots which
|
||||||
|
must appear in a name given to
|
||||||
|
.Fn res_query
|
||||||
|
(see
|
||||||
|
.Xr resolver 3 )
|
||||||
|
before an
|
||||||
|
.Em initial absolute query
|
||||||
|
will be made.
|
||||||
|
The default for
|
||||||
|
.Ar n
|
||||||
|
is
|
||||||
|
.Dq 1 ,
|
||||||
|
meaning that if there are
|
||||||
|
.Em any
|
||||||
|
dots in a name, the name will be tried first as an absolute name before any
|
||||||
|
.Em search list
|
||||||
|
elements are appended to it.
|
||||||
|
Acceptable values of
|
||||||
|
.Ar n
|
||||||
|
are between 0 and 255 inclusive.
|
||||||
|
.It debug
|
||||||
|
enables debugging traces for the resolver
|
||||||
|
XXXJR if anything actually looked at
|
||||||
|
.Dv confdata->resdebug .
|
||||||
|
At present the option is just recognised but not used by
|
||||||
|
the BIND9 implementation.
|
||||||
|
.It no_tld_query
|
||||||
|
tells the resolver not to attempt to resolve a
|
||||||
|
top level domain name, i.e. a name containing no dots.
|
||||||
|
Use of this option does not prevent the resolver from obeying the
|
||||||
|
standard
|
||||||
|
.Ar domain
|
||||||
|
and
|
||||||
|
.Ar search
|
||||||
|
rules with the given name.
|
||||||
|
XXXJR At present this option is recognised but is otherwise unused
|
||||||
|
in BIND9.
|
||||||
|
.It missing
|
||||||
|
XXXJR what about the other BIND8 resolver options like rotate and
|
||||||
|
timeout? Shouldn't these be provided for backwards compatibility?
|
||||||
|
.El
|
||||||
|
.El
|
||||||
|
.Pp
|
||||||
|
The
|
||||||
|
.Li domain
|
||||||
|
and
|
||||||
|
.Li search
|
||||||
|
keywords are mutually exclusive.
|
||||||
|
If more than one instance of these keywords is present,
|
||||||
|
the last instance wins.
|
||||||
|
.Sh FILES
|
||||||
|
.Pa /etc/resolv.conf
|
||||||
|
.Pa <lwres/lwres.h>
|
||||||
|
.Sh SEE ALSO
|
||||||
|
.Xr gethostbyname 3 ,
|
||||||
|
.Xr lwres_config 3 ,
|
||||||
|
.Xr lwres 3 ,
|
||||||
|
.Xr resolver 3 ,
|
||||||
|
.Xr hostname 7 ,
|
||||||
|
.Xr lwresd 8 ,
|
||||||
|
.Xr named 8 ,
|
||||||
|
"BIND9 Administrators Manual".
|
||||||
|
.Sh BUGS
|
||||||
|
Unrecognised directives and syntax errors in
|
||||||
|
.Pa /etc/resolv.conf
|
||||||
|
are usually silently ignored, though
|
||||||
|
.Er LWRES_R_FAILURE
|
||||||
|
can be returned by the lightweight resolver functions described in
|
||||||
|
.Xr lwres_config 3
|
||||||
|
which parse this file.
|
||||||
Loading…
x
Reference in New Issue
Block a user