.\" Copyright (C) 2004  Internet Systems Consortium, Inc. ("ISC")
.\" Copyright (C) 2000, 2001  Internet Software Consortium.
.\"
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.\" purpose with or without fee is hereby granted, provided that the above
.\" copyright notice and this permission notice appear in all copies.
.\"
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.\" REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
.\" AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
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.\" PERFORMANCE OF THIS SOFTWARE.
.\"
.\" $Id: lwresd.8,v 1.13.2.2 2004/06/03 05:21:13 marka Exp $
.\"
.TH "LWRESD" "8" "June 30, 2000" "BIND9" ""
.SH NAME
lwresd \- lightweight resolver daemon
.SH SYNOPSIS
.sp
\fBlwresd\fR [ \fB-C \fIconfig-file\fB\fR ]  [ \fB-d \fIdebug-level\fB\fR ]  [ \fB-f\fR ]  [ \fB-g\fR ]  [ \fB-i \fIpid-file\fB\fR ]  [ \fB-n \fI#cpus\fB\fR ]  [ \fB-P \fIport\fB\fR ]  [ \fB-p \fIport\fB\fR ]  [ \fB-s\fR ]  [ \fB-t \fIdirectory\fB\fR ]  [ \fB-u \fIuser\fB\fR ]  [ \fB-v\fR ] 
.SH "DESCRIPTION"
.PP
\fBlwresd\fR is the daemon providing name lookup
services to clients that use the BIND 9 lightweight resolver
library. It is essentially a stripped-down, caching-only name
server that answers queries using the BIND 9 lightweight
resolver protocol rather than the DNS protocol.
.PP
\fBlwresd\fR listens for resolver queries on a
UDP port on the IPv4 loopback interface, 127.0.0.1. This
means that \fBlwresd\fR can only be used by
processes running on the local machine. By default UDP port
number 921 is used for lightweight resolver requests and
responses.
.PP
Incoming lightweight resolver requests are decoded by the
server which then resolves them using the DNS protocol. When
the DNS lookup completes, \fBlwresd\fR encodes
the answers in the lightweight resolver format and returns
them to the client that made the request.
.PP
If \fI/etc/resolv.conf\fR contains any
\fBnameserver\fR entries, \fBlwresd\fR
sends recursive DNS queries to those servers. This is similar
to the use of forwarders in a caching name server. If no
\fBnameserver\fR entries are present, or if
forwarding fails, \fBlwresd\fR resolves the
queries autonomously starting at the root name servers, using
a built-in list of root server hints.
.SH "OPTIONS"
.TP
\fB-C \fIconfig-file\fB\fR
Use \fIconfig-file\fR as the
configuration file instead of the default,
\fI/etc/resolv.conf\fR.
.TP
\fB-d \fIdebug-level\fB\fR
Set the daemon's debug level to \fIdebug-level\fR.
Debugging traces from \fBlwresd\fR become
more verbose as the debug level increases.
.TP
\fB-f\fR
Run the server in the foreground (i.e. do not daemonize).
.TP
\fB-g\fR
Run the server in the foreground and force all logging
to \fIstderr\fR.
.TP
\fB-n \fI#cpus\fB\fR
Create \fI#cpus\fR worker threads
to take advantage of multiple CPUs. If not specified,
\fBlwresd\fR will try to determine the
number of CPUs present and create one thread per CPU.
If it is unable to determine the number of CPUs, a
single worker thread will be created.
.TP
\fB-P \fIport\fB\fR
Listen for lightweight resolver queries on port
\fIport\fR. If
not specified, the default is port 921.
.TP
\fB-p \fIport\fB\fR
Send DNS lookups to port \fIport\fR. If not
specified, the default is port 53. This provides a
way of testing the lightweight resolver daemon with a
name server that listens for queries on a non-standard
port number.
.TP
\fB-s\fR
Write memory usage statistics to \fIstdout\fR
on exit.
.sp
.RS
.B "Note:"
This option is mainly of interest to BIND 9 developers
and may be removed or changed in a future release.
.RE
.sp
.TP
\fB-t \fIdirectory\fB\fR
\fBchroot()\fR to \fIdirectory\fR after
processing the command line arguments, but before
reading the configuration file.
.sp
.RS
.B "Warning:"
This option should be used in conjunction with the
\fB-u\fR option, as chrooting a process
running as root doesn't enhance security on most
systems; the way \fBchroot()\fR is
defined allows a process with root privileges to
escape a chroot jail.
.RE
.sp
.TP
\fB-u \fIuser\fB\fR
\fBsetuid()\fR to \fIuser\fR after completing
privileged operations, such as creating sockets that
listen on privileged ports.
.TP
\fB-v\fR
Report the version number and exit.
.SH "FILES"
.TP
\fB\fI/etc/resolv.conf\fB\fR
The default configuration file.
.TP
\fB\fI/var/run/lwresd.pid\fB\fR
The default process-id file.
.SH "SEE ALSO"
.PP
\fBnamed\fR(8),
\fBlwres\fR(3),
\fBresolver\fR(5).
.SH "AUTHOR"
.PP
Internet Systems Consortium