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8fe8f97e688779add9cd042a9db4ddb7b117cce2Stephan Bosch<a name="man.lwresd"></a><div class="titlepage"></div>
8fe8f97e688779add9cd042a9db4ddb7b117cce2Stephan Bosch — lightweight resolver daemon
4d955db590c3d76a631dfc5d37bcdf578a43e55aStephan Bosch [<code class="option">-c <em class="replaceable"><code>config-file</code></em></code>]
8fe8f97e688779add9cd042a9db4ddb7b117cce2Stephan Bosch [<code class="option">-C <em class="replaceable"><code>config-file</code></em></code>]
4d955db590c3d76a631dfc5d37bcdf578a43e55aStephan Bosch [<code class="option">-d <em class="replaceable"><code>debug-level</code></em></code>]
8fe8f97e688779add9cd042a9db4ddb7b117cce2Stephan Bosch [<code class="option">-i <em class="replaceable"><code>pid-file</code></em></code>]
4d955db590c3d76a631dfc5d37bcdf578a43e55aStephan Bosch [<code class="option">-m <em class="replaceable"><code>flag</code></em></code>]
4d955db590c3d76a631dfc5d37bcdf578a43e55aStephan Bosch [<code class="option">-n <em class="replaceable"><code>#cpus</code></em></code>]
4d955db590c3d76a631dfc5d37bcdf578a43e55aStephan Bosch [<code class="option">-P <em class="replaceable"><code>port</code></em></code>]
4d955db590c3d76a631dfc5d37bcdf578a43e55aStephan Bosch [<code class="option">-p <em class="replaceable"><code>port</code></em></code>]
4d955db590c3d76a631dfc5d37bcdf578a43e55aStephan Bosch [<code class="option">-t <em class="replaceable"><code>directory</code></em></code>]
4d955db590c3d76a631dfc5d37bcdf578a43e55aStephan Bosch [<code class="option">-u <em class="replaceable"><code>user</code></em></code>]
8fe8f97e688779add9cd042a9db4ddb7b117cce2Stephan Bosch<a name="id-1.14.18.7"></a><h2>DESCRIPTION</h2>
8fe8f97e688779add9cd042a9db4ddb7b117cce2Stephan Bosch <p><span class="command"><strong>lwresd</strong></span>
8fe8f97e688779add9cd042a9db4ddb7b117cce2Stephan Bosch is the daemon providing name lookup
8fe8f97e688779add9cd042a9db4ddb7b117cce2Stephan Bosch services to clients that use the BIND 9 lightweight resolver
8fe8f97e688779add9cd042a9db4ddb7b117cce2Stephan Bosch library. It is essentially a stripped-down, caching-only name
8fe8f97e688779add9cd042a9db4ddb7b117cce2Stephan Bosch server that answers queries using the BIND 9 lightweight
8fe8f97e688779add9cd042a9db4ddb7b117cce2Stephan Bosch resolver protocol rather than the DNS protocol.
8fe8f97e688779add9cd042a9db4ddb7b117cce2Stephan Bosch <p><span class="command"><strong>lwresd</strong></span>
8fe8f97e688779add9cd042a9db4ddb7b117cce2Stephan Bosch listens for resolver queries on a
8fe8f97e688779add9cd042a9db4ddb7b117cce2Stephan Bosch UDP port on the IPv4 loopback interface, 127.0.0.1. This
8fe8f97e688779add9cd042a9db4ddb7b117cce2Stephan Bosch means that <span class="command"><strong>lwresd</strong></span> can only be used by
8fe8f97e688779add9cd042a9db4ddb7b117cce2Stephan Bosch processes running on the local machine. By default, UDP port
8fe8f97e688779add9cd042a9db4ddb7b117cce2Stephan Bosch number 921 is used for lightweight resolver requests and
32f28ff765ef6983af0df78ebc5289b478abf3feStephan Bosch Incoming lightweight resolver requests are decoded by the
32f28ff765ef6983af0df78ebc5289b478abf3feStephan Bosch server which then resolves them using the DNS protocol. When
32f28ff765ef6983af0df78ebc5289b478abf3feStephan Bosch the DNS lookup completes, <span class="command"><strong>lwresd</strong></span> encodes
32f28ff765ef6983af0df78ebc5289b478abf3feStephan Bosch the answers in the lightweight resolver format and returns
8fe8f97e688779add9cd042a9db4ddb7b117cce2Stephan Bosch them to the client that made the request.
32f28ff765ef6983af0df78ebc5289b478abf3feStephan Bosch If <code class="filename">/etc/resolv.conf</code> contains any
32f28ff765ef6983af0df78ebc5289b478abf3feStephan Bosch <code class="option">nameserver</code> entries, <span class="command"><strong>lwresd</strong></span>
32f28ff765ef6983af0df78ebc5289b478abf3feStephan Bosch sends recursive DNS queries to those servers. This is similar
32f28ff765ef6983af0df78ebc5289b478abf3feStephan Bosch to the use of forwarders in a caching name server. If no
8fe8f97e688779add9cd042a9db4ddb7b117cce2Stephan Bosch <code class="option">nameserver</code> entries are present, or if
8fe8f97e688779add9cd042a9db4ddb7b117cce2Stephan Bosch forwarding fails, <span class="command"><strong>lwresd</strong></span> resolves the
8fe8f97e688779add9cd042a9db4ddb7b117cce2Stephan Bosch queries autonomously starting at the root name servers, using
8fe8f97e688779add9cd042a9db4ddb7b117cce2Stephan Bosch a built-in list of root server hints.
8fe8f97e688779add9cd042a9db4ddb7b117cce2Stephan Bosch <div class="variablelist"><dl class="variablelist">
72fc989c43a0dc94ec2f114b5e221beeab45519bTimo Sirainen Use IPv4 only even if the host machine is capable of IPv6.
8fe8f97e688779add9cd042a9db4ddb7b117cce2Stephan Bosch <code class="option">-4</code> and <code class="option">-6</code> are mutually
8fe8f97e688779add9cd042a9db4ddb7b117cce2Stephan Bosch Use IPv6 only even if the host machine is capable of IPv4.
8fe8f97e688779add9cd042a9db4ddb7b117cce2Stephan Bosch <code class="option">-4</code> and <code class="option">-6</code> are mutually
8fe8f97e688779add9cd042a9db4ddb7b117cce2Stephan Bosch<dt><span class="term">-c <em class="replaceable"><code>config-file</code></em></span></dt>
32f28ff765ef6983af0df78ebc5289b478abf3feStephan Bosch Use <em class="replaceable"><code>config-file</code></em> as the
32f28ff765ef6983af0df78ebc5289b478abf3feStephan Bosch configuration file instead of the default,
32f28ff765ef6983af0df78ebc5289b478abf3feStephan Bosch <code class="filename">/etc/lwresd.conf</code>.
32f28ff765ef6983af0df78ebc5289b478abf3feStephan Bosch <code class="option">-c</code> can not be used with <code class="option">-C</code>.
8fe8f97e688779add9cd042a9db4ddb7b117cce2Stephan Bosch<dt><span class="term">-C <em class="replaceable"><code>config-file</code></em></span></dt>
8fe8f97e688779add9cd042a9db4ddb7b117cce2Stephan Bosch Use <em class="replaceable"><code>config-file</code></em> as the
8fe8f97e688779add9cd042a9db4ddb7b117cce2Stephan Bosch configuration file instead of the default,
8fe8f97e688779add9cd042a9db4ddb7b117cce2Stephan Bosch <code class="filename">/etc/resolv.conf</code>.
4d955db590c3d76a631dfc5d37bcdf578a43e55aStephan Bosch <code class="option">-C</code> can not be used with <code class="option">-c</code>.
8fe8f97e688779add9cd042a9db4ddb7b117cce2Stephan Bosch<dt><span class="term">-d <em class="replaceable"><code>debug-level</code></em></span></dt>
8fe8f97e688779add9cd042a9db4ddb7b117cce2Stephan Bosch Set the daemon's debug level to <em class="replaceable"><code>debug-level</code></em>.
8fe8f97e688779add9cd042a9db4ddb7b117cce2Stephan Bosch Debugging traces from <span class="command"><strong>lwresd</strong></span> become
8fe8f97e688779add9cd042a9db4ddb7b117cce2Stephan Bosch more verbose as the debug level increases.
8fe8f97e688779add9cd042a9db4ddb7b117cce2Stephan Bosch Run the server in the foreground (i.e. do not daemonize).
8fe8f97e688779add9cd042a9db4ddb7b117cce2Stephan Bosch Run the server in the foreground and force all logging
8fe8f97e688779add9cd042a9db4ddb7b117cce2Stephan Bosch<dt><span class="term">-i <em class="replaceable"><code>pid-file</code></em></span></dt>
8fe8f97e688779add9cd042a9db4ddb7b117cce2Stephan Bosch Use <em class="replaceable"><code>pid-file</code></em> as the
8fe8f97e688779add9cd042a9db4ddb7b117cce2Stephan Bosch PID file instead of the default,
b7e953d7eecd18f1d0de701cc181e8830d8167b1Stephan Bosch <code class="filename">/var/run/lwresd/lwresd.pid</code>.
b7e953d7eecd18f1d0de701cc181e8830d8167b1Stephan Bosch<dt><span class="term">-m <em class="replaceable"><code>flag</code></em></span></dt>
b7e953d7eecd18f1d0de701cc181e8830d8167b1Stephan Bosch Turn on memory usage debugging flags. Possible flags are
b7e953d7eecd18f1d0de701cc181e8830d8167b1Stephan Bosch <em class="replaceable"><code>usage</code></em>,
b7e953d7eecd18f1d0de701cc181e8830d8167b1Stephan Bosch <em class="replaceable"><code>trace</code></em>,
b7e953d7eecd18f1d0de701cc181e8830d8167b1Stephan Bosch <em class="replaceable"><code>record</code></em>,
b7e953d7eecd18f1d0de701cc181e8830d8167b1Stephan Bosch <em class="replaceable"><code>size</code></em>, and
b7e953d7eecd18f1d0de701cc181e8830d8167b1Stephan Bosch <em class="replaceable"><code>mctx</code></em>.
b7e953d7eecd18f1d0de701cc181e8830d8167b1Stephan Bosch These correspond to the ISC_MEM_DEBUGXXXX flags described in
b7e953d7eecd18f1d0de701cc181e8830d8167b1Stephan Bosch <code class="filename"><isc/mem.h></code>.
b7e953d7eecd18f1d0de701cc181e8830d8167b1Stephan Bosch<dt><span class="term">-n <em class="replaceable"><code>#cpus</code></em></span></dt>
b7e953d7eecd18f1d0de701cc181e8830d8167b1Stephan Bosch Create <em class="replaceable"><code>#cpus</code></em> worker threads
b7e953d7eecd18f1d0de701cc181e8830d8167b1Stephan Bosch to take advantage of multiple CPUs. If not specified,
b7e953d7eecd18f1d0de701cc181e8830d8167b1Stephan Bosch <span class="command"><strong>lwresd</strong></span> will try to determine the
b7e953d7eecd18f1d0de701cc181e8830d8167b1Stephan Bosch number of CPUs present and create one thread per CPU.
b7e953d7eecd18f1d0de701cc181e8830d8167b1Stephan Bosch If it is unable to determine the number of CPUs, a
8fe8f97e688779add9cd042a9db4ddb7b117cce2Stephan Bosch single worker thread will be created.
8fe8f97e688779add9cd042a9db4ddb7b117cce2Stephan Bosch<dt><span class="term">-P <em class="replaceable"><code>port</code></em></span></dt>
32f28ff765ef6983af0df78ebc5289b478abf3feStephan Bosch Listen for lightweight resolver queries on port
8fe8f97e688779add9cd042a9db4ddb7b117cce2Stephan Bosch <em class="replaceable"><code>port</code></em>. If
8fe8f97e688779add9cd042a9db4ddb7b117cce2Stephan Bosch not specified, the default is port 921.
8fe8f97e688779add9cd042a9db4ddb7b117cce2Stephan Bosch<dt><span class="term">-p <em class="replaceable"><code>port</code></em></span></dt>
8fe8f97e688779add9cd042a9db4ddb7b117cce2Stephan Bosch Send DNS lookups to port <em class="replaceable"><code>port</code></em>. If not
8fe8f97e688779add9cd042a9db4ddb7b117cce2Stephan Bosch specified, the default is port 53. This provides a
8fe8f97e688779add9cd042a9db4ddb7b117cce2Stephan Bosch way of testing the lightweight resolver daemon with a
8fe8f97e688779add9cd042a9db4ddb7b117cce2Stephan Bosch name server that listens for queries on a non-standard
32f28ff765ef6983af0df78ebc5289b478abf3feStephan Bosch Write memory usage statistics to <code class="filename">stdout</code>
8fe8f97e688779add9cd042a9db4ddb7b117cce2Stephan Bosch <div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
8fe8f97e688779add9cd042a9db4ddb7b117cce2Stephan Bosch This option is mainly of interest to BIND 9 developers
8fe8f97e688779add9cd042a9db4ddb7b117cce2Stephan Bosch and may be removed or changed in a future release.
72fc989c43a0dc94ec2f114b5e221beeab45519bTimo Sirainen<dt><span class="term">-t <em class="replaceable"><code>directory</code></em></span></dt>
8fe8f97e688779add9cd042a9db4ddb7b117cce2Stephan Bosch to <em class="replaceable"><code>directory</code></em> after
639bb36b12b9f9bb54c8bb1be50eac623622f8a0Timo Sirainen processing the command line arguments, but before
8fe8f97e688779add9cd042a9db4ddb7b117cce2Stephan Bosch reading the configuration file.
8fe8f97e688779add9cd042a9db4ddb7b117cce2Stephan Bosch <div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;">
8fe8f97e688779add9cd042a9db4ddb7b117cce2Stephan Bosch This option should be used in conjunction with the
8fe8f97e688779add9cd042a9db4ddb7b117cce2Stephan Bosch <code class="option">-u</code> option, as chrooting a process
8fe8f97e688779add9cd042a9db4ddb7b117cce2Stephan Bosch running as root doesn't enhance security on most
8fe8f97e688779add9cd042a9db4ddb7b117cce2Stephan Bosch systems; the way <code class="function">chroot(2)</code> is
639bb36b12b9f9bb54c8bb1be50eac623622f8a0Timo Sirainen defined allows a process with root privileges to
8fe8f97e688779add9cd042a9db4ddb7b117cce2Stephan Bosch escape a chroot jail.
8fe8f97e688779add9cd042a9db4ddb7b117cce2Stephan Bosch<dt><span class="term">-u <em class="replaceable"><code>user</code></em></span></dt>
8fe8f97e688779add9cd042a9db4ddb7b117cce2Stephan Bosch to <em class="replaceable"><code>user</code></em> after completing
8fe8f97e688779add9cd042a9db4ddb7b117cce2Stephan Bosch privileged operations, such as creating sockets that
8fe8f97e688779add9cd042a9db4ddb7b117cce2Stephan Bosch listen on privileged ports.
639bb36b12b9f9bb54c8bb1be50eac623622f8a0Timo Sirainen Report the version number and exit.
639bb36b12b9f9bb54c8bb1be50eac623622f8a0Timo Sirainen <div class="variablelist"><dl class="variablelist">
4351efdddced25735d629496f6c68c9d0cfb896aTimo Sirainen<dt><span class="term"><code class="filename">/etc/resolv.conf</code></span></dt>
72fc989c43a0dc94ec2f114b5e221beeab45519bTimo Sirainen The default configuration file.
8fe8f97e688779add9cd042a9db4ddb7b117cce2Stephan Bosch<dt><span class="term"><code class="filename">/var/run/lwresd.pid</code></span></dt>
8fe8f97e688779add9cd042a9db4ddb7b117cce2Stephan Bosch The default process-id file.
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