.\" Copyright (C) 2004, 2005, 2007-2009 Internet Systems Consortium, Inc. ("ISC")
.\" Copyright (C) 2000, 2001 Internet Software Consortium.
.\" 
.\" Permission to use, copy, modify, and/or 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 ISC DISCLAIMS ALL WARRANTIES WITH
.\" REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
.\" AND FITNESS. IN NO EVENT SHALL ISC 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: lwresd.8,v 1.31 2009-07-11 01:12:45 tbox Exp $
.\"
.hy 0
.ad l
.\"     Title: lwresd
.\"    Author: 
.\" Generator: DocBook XSL Stylesheets v1.71.1 <http://docbook.sf.net/>
.\"      Date: June 30, 2000
.\"    Manual: BIND9
.\"    Source: BIND9
.\"
.TH "LWRESD" "8" "June 30, 2000" "BIND9" "BIND9"
.\" disable hyphenation
.nh
.\" disable justification (adjust text to left margin only)
.ad l
.SH "NAME"
lwresd \- lightweight resolver daemon
.SH "SYNOPSIS"
.HP 7
\fBlwresd\fR [\fB\-c\ \fR\fB\fIconfig\-file\fR\fR] [\fB\-C\ \fR\fB\fIconfig\-file\fR\fR] [\fB\-d\ \fR\fB\fIdebug\-level\fR\fR] [\fB\-f\fR] [\fB\-g\fR] [\fB\-i\ \fR\fB\fIpid\-file\fR\fR] [\fB\-m\ \fR\fB\fIflag\fR\fR] [\fB\-n\ \fR\fB\fI#cpus\fR\fR] [\fB\-P\ \fR\fB\fIport\fR\fR] [\fB\-p\ \fR\fB\fIport\fR\fR] [\fB\-s\fR] [\fB\-t\ \fR\fB\fIdirectory\fR\fR] [\fB\-u\ \fR\fB\fIuser\fR\fR] [\fB\-v\fR] [\fB\-4\fR] [\fB\-6\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"
.PP
\-4
.RS 4
Use IPv4 only even if the host machine is capable of IPv6.
\fB\-4\fR
and
\fB\-6\fR
are mutually exclusive.
.RE
.PP
\-6
.RS 4
Use IPv6 only even if the host machine is capable of IPv4.
\fB\-4\fR
and
\fB\-6\fR
are mutually exclusive.
.RE
.PP
\-c \fIconfig\-file\fR
.RS 4
Use
\fIconfig\-file\fR
as the configuration file instead of the default,
\fI/etc/lwresd.conf\fR.
\fB\-c\fR
can not be used with
\fB\-C\fR.
.RE
.PP
\-C \fIconfig\-file\fR
.RS 4
Use
\fIconfig\-file\fR
as the configuration file instead of the default,
\fI/etc/resolv.conf\fR.
\fB\-C\fR
can not be used with
\fB\-c\fR.
.RE
.PP
\-d \fIdebug\-level\fR
.RS 4
Set the daemon's debug level to
\fIdebug\-level\fR. Debugging traces from
\fBlwresd\fR
become more verbose as the debug level increases.
.RE
.PP
\-f
.RS 4
Run the server in the foreground (i.e. do not daemonize).
.RE
.PP
\-g
.RS 4
Run the server in the foreground and force all logging to
\fIstderr\fR.
.RE
.PP
\-i \fIpid\-file\fR
.RS 4
Use
\fIpid\-file\fR
as the PID file instead of the default,
\fI/var/run/lwresd/lwresd.pid\fR.
.RE
.PP
\-m \fIflag\fR
.RS 4
Turn on memory usage debugging flags. Possible flags are
\fIusage\fR,
\fItrace\fR,
\fIrecord\fR,
\fIsize\fR, and
\fImctx\fR. These correspond to the ISC_MEM_DEBUGXXXX flags described in
\fI<isc/mem.h>\fR.
.RE
.PP
\-n \fI#cpus\fR
.RS 4
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.
.RE
.PP
\-P \fIport\fR
.RS 4
Listen for lightweight resolver queries on port
\fIport\fR. If not specified, the default is port 921.
.RE
.PP
\-p \fIport\fR
.RS 4
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.
.RE
.PP
\-s
.RS 4
Write memory usage statistics to
\fIstdout\fR
on exit.
.RS
.B "Note:"
This option is mainly of interest to BIND 9 developers and may be removed or changed in a future release.
.RE
.RE
.PP
\-t \fIdirectory\fR
.RS 4
Chroot to
\fIdirectory\fR
after processing the command line arguments, but before reading the configuration file.
.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(2)\fR
is defined allows a process with root privileges to escape a chroot jail.
.RE
.RE
.PP
\-u \fIuser\fR
.RS 4
Setuid to
\fIuser\fR
after completing privileged operations, such as creating sockets that listen on privileged ports.
.RE
.PP
\-v
.RS 4
Report the version number and exit.
.RE
.SH "FILES"
.PP
\fI/etc/resolv.conf\fR
.RS 4
The default configuration file.
.RE
.PP
\fI/var/run/lwresd.pid\fR
.RS 4
The default process\-id file.
.RE
.SH "SEE ALSO"
.PP
\fBnamed\fR(8),
\fBlwres\fR(3),
\fBresolver\fR(5).
.SH "AUTHOR"
.PP
Internet Systems Consortium
.SH "COPYRIGHT"
Copyright \(co 2004, 2005, 2007\-2009 Internet Systems Consortium, Inc. ("ISC")
.br
Copyright \(co 2000, 2001 Internet Software Consortium.
.br