<refentry xmlns="http://docbook.org/ns/docbook" version="5.0" xml:id="man.lwresd">

<info>

<date>2009-01-20</date>

</info>

<refentryinfo>

<corpname>ISC</corpname>

<corpauthor>Internet Systems Consortium, Inc.</corpauthor>

</refentryinfo>

<refmeta>

<refentrytitle><application>lwresd</application></refentrytitle>

<manvolnum>8</manvolnum>

<refmiscinfo>BIND9</refmiscinfo>

</refmeta>

<refnamediv>

<refname><application>lwresd</application></refname>

<refpurpose>lightweight resolver daemon</refpurpose>

</refnamediv>

<docinfo>

<copyright>

<year>2004</year>

<year>2005</year>

<year>2007</year>

<year>2008</year>

<year>2009</year>

<year>2014</year>

<year>2015</year>

<year>2016</year>

<holder>Internet Systems Consortium, Inc. ("ISC")</holder>

</copyright>

<copyright>

<year>2000</year>

<year>2001</year>

<holder>Internet Software Consortium.</holder>

</copyright>

</docinfo>

<refsynopsisdiv>

<cmdsynopsis sepchar=" ">

<command>lwresd</command>

<arg choice="opt" rep="norepeat"><option>-c <replaceable class="parameter">config-file</replaceable></option></arg>

<arg choice="opt" rep="norepeat"><option>-C <replaceable class="parameter">config-file</replaceable></option></arg>

<arg choice="opt" rep="norepeat"><option>-d <replaceable class="parameter">debug-level</replaceable></option></arg>

<arg choice="opt" rep="norepeat"><option>-f</option></arg>

<arg choice="opt" rep="norepeat"><option>-g</option></arg>

<arg choice="opt" rep="norepeat"><option>-i <replaceable class="parameter">pid-file</replaceable></option></arg>

<arg choice="opt" rep="norepeat"><option>-m <replaceable class="parameter">flag</replaceable></option></arg>

<arg choice="opt" rep="norepeat"><option>-n <replaceable class="parameter">#cpus</replaceable></option></arg>

<arg choice="opt" rep="norepeat"><option>-P <replaceable class="parameter">port</replaceable></option></arg>

<arg choice="opt" rep="norepeat"><option>-p <replaceable class="parameter">port</replaceable></option></arg>

<arg choice="opt" rep="norepeat"><option>-s</option></arg>

<arg choice="opt" rep="norepeat"><option>-t <replaceable class="parameter">directory</replaceable></option></arg>

<arg choice="opt" rep="norepeat"><option>-u <replaceable class="parameter">user</replaceable></option></arg>

<arg choice="opt" rep="norepeat"><option>-v</option></arg>

<arg choice="opt" rep="norepeat"><option>-4</option></arg>

<arg choice="opt" rep="norepeat"><option>-6</option></arg>

</cmdsynopsis>

</refsynopsisdiv>

<refsection><info><title>DESCRIPTION</title></info>

<para><command>lwresd</command>

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.

</para>

<para><command>lwresd</command>

listens for resolver queries on a

UDP port on the IPv4 loopback interface, 127.0.0.1. This

means that <command>lwresd</command> 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.

</para>

<para>

Incoming lightweight resolver requests are decoded by the

server which then resolves them using the DNS protocol. When

the DNS lookup completes, <command>lwresd</command> encodes

the answers in the lightweight resolver format and returns

them to the client that made the request.

</para>

<para>

If <filename>/etc/resolv.conf</filename> contains any

<option>nameserver</option> entries, <command>lwresd</command>

sends recursive DNS queries to those servers. This is similar

to the use of forwarders in a caching name server. If no

<option>nameserver</option> entries are present, or if

forwarding fails, <command>lwresd</command> resolves the

queries autonomously starting at the root name servers, using

a built-in list of root server hints.

</para>

</refsection>

<refsection><info><title>OPTIONS</title></info>

<variablelist>

<varlistentry>

<term>-4</term>

<listitem>

<para>

Use IPv4 only even if the host machine is capable of IPv6.

<option>-4</option> and <option>-6</option> are mutually

exclusive.

</para>

</listitem>

</varlistentry>

<varlistentry>

<term>-6</term>

<listitem>

<para>

Use IPv6 only even if the host machine is capable of IPv4.

<option>-4</option> and <option>-6</option> are mutually

exclusive.

</para>

</listitem>

</varlistentry>

<!-- this is in source but not mentioned? does this matter? -->

<varlistentry>

<term>-c <replaceable class="parameter">config-file</replaceable></term>

<listitem>

<para>

Use <replaceable class="parameter">config-file</replaceable> as the

configuration file instead of the default,

<filename>/etc/lwresd.conf</filename>.

<!-- Should this be an absolute path name? -->

<option>-c</option> can not be used with <option>-C</option>.

</para>

</listitem>

</varlistentry>

<varlistentry>

<term>-C <replaceable class="parameter">config-file</replaceable></term>

<listitem>

<para>

Use <replaceable class="parameter">config-file</replaceable> as the

configuration file instead of the default,

<filename>/etc/resolv.conf</filename>.

<option>-C</option> can not be used with <option>-c</option>.

</para>

</listitem>

</varlistentry>

<varlistentry>

<term>-d <replaceable class="parameter">debug-level</replaceable></term>

<listitem>

<para>

Set the daemon's debug level to <replaceable class="parameter">debug-level</replaceable>.

Debugging traces from <command>lwresd</command> become

more verbose as the debug level increases.

</para>

</listitem>

</varlistentry>

<varlistentry>

<term>-f</term>

<listitem>

<para>

Run the server in the foreground (i.e. do not daemonize).

</para>

</listitem>

</varlistentry>

<varlistentry>

<term>-g</term>

<listitem>

<para>

Run the server in the foreground and force all logging

to <filename>stderr</filename>.

</para>

</listitem>

</varlistentry>

<varlistentry>

<term>-i <replaceable class="parameter">pid-file</replaceable></term>

<listitem>

<para>

Use <replaceable class="parameter">pid-file</replaceable> as the

PID file instead of the default,

<filename>/var/run/lwresd/lwresd.pid</filename>.

</para>

</listitem>

</varlistentry>

<varlistentry>

<term>-m <replaceable class="parameter">flag</replaceable></term>

<listitem>

<para>

Turn on memory usage debugging flags. Possible flags are

<replaceable class="parameter">usage</replaceable>,

<replaceable class="parameter">trace</replaceable>,

<replaceable class="parameter">record</replaceable>,

<replaceable class="parameter">size</replaceable>, and

<replaceable class="parameter">mctx</replaceable>.

These correspond to the ISC_MEM_DEBUGXXXX flags described in

<filename>&lt;isc/mem.h&gt;</filename>.

</para>

</listitem>

</varlistentry>

<varlistentry>

<term>-n <replaceable class="parameter">#cpus</replaceable></term>

<listitem>

<para>

Create <replaceable class="parameter">#cpus</replaceable> worker threads

to take advantage of multiple CPUs. If not specified,

<command>lwresd</command> 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.

</para>

</listitem>

</varlistentry>

<varlistentry>

<term>-P <replaceable class="parameter">port</replaceable></term>

<listitem>

<para>

Listen for lightweight resolver queries on port

<replaceable class="parameter">port</replaceable>. If

not specified, the default is port 921.

</para>

</listitem>

</varlistentry>

<varlistentry>

<term>-p <replaceable class="parameter">port</replaceable></term>

<listitem>

<para>

Send DNS lookups to port <replaceable class="parameter">port</replaceable>. 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.

</para>

</listitem>

</varlistentry>

<varlistentry>

<term>-s</term>

<listitem>

<para>

Write memory usage statistics to <filename>stdout</filename>

on exit.

</para>

<note>

<para>

This option is mainly of interest to BIND 9 developers

and may be removed or changed in a future release.

</para>

</note>

</listitem>

</varlistentry>

<varlistentry>

<term>-t <replaceable class="parameter">directory</replaceable></term>

<listitem>

<para>Chroot

to <replaceable class="parameter">directory</replaceable> after

processing the command line arguments, but before

reading the configuration file.

</para>

<warning>

<para>

This option should be used in conjunction with the

<option>-u</option> option, as chrooting a process

running as root doesn't enhance security on most

systems; the way <function>chroot(2)</function> is

defined allows a process with root privileges to

escape a chroot jail.

</para>

</warning>

</listitem>

</varlistentry>

<varlistentry>

<term>-u <replaceable class="parameter">user</replaceable></term>

<listitem>

<para>Setuid

to <replaceable class="parameter">user</replaceable> after completing

privileged operations, such as creating sockets that

listen on privileged ports.

</para>

</listitem>

</varlistentry>

<varlistentry>

<term>-v</term>

<listitem>

<para>

Report the version number and exit.

</para>

</listitem>

</varlistentry>

</variablelist>

</refsection>

<refsection><info><title>FILES</title></info>

<variablelist>

<varlistentry>

<term><filename>/etc/resolv.conf</filename></term>

<listitem>

<para>

The default configuration file.

</para>

</listitem>

</varlistentry>

<varlistentry>

<term><filename>/var/run/lwresd.pid</filename></term>

<listitem>

<para>

The default process-id file.

</para>

</listitem>

</varlistentry>

</variablelist>

</refsection>

<refsection><info><title>SEE ALSO</title></info>

<para><citerefentry>

<refentrytitle>named</refentrytitle><manvolnum>8</manvolnum>

</citerefentry>,

<citerefentry>

<refentrytitle>lwres</refentrytitle><manvolnum>3</manvolnum>

</citerefentry>,

<citerefentry>

<refentrytitle>resolver</refentrytitle><manvolnum>5</manvolnum>

</citerefentry>.

</para>

</refsection>

</refentry>