lwresd.html revision 60084a1a5a9e570842b8147ff4c34b68ce4de7f8
<!--
- Copyright (C) 2000, 2001 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.
-->
<HTML
><HEAD
><TITLE
>lwresd</TITLE
><META
NAME="GENERATOR"
CONTENT="Modular DocBook HTML Stylesheet Version 1.61
"></HEAD
><BODY
CLASS="REFENTRY"
BGCOLOR="#FFFFFF"
TEXT="#000000"
LINK="#0000FF"
VLINK="#840084"
ALINK="#0000FF"
><H1
><A
NAME="AEN1"
><SPAN
CLASS="APPLICATION"
>lwresd</SPAN
></A
></H1
><DIV
CLASS="REFNAMEDIV"
><A
NAME="AEN9"
></A
><H2
>Name</H2
><SPAN
CLASS="APPLICATION"
>lwresd</SPAN
> -- lightweight resolver daemon</DIV
><DIV
CLASS="REFSYNOPSISDIV"
><A
NAME="AEN13"
></A
><H2
>Synopsis</H2
><P
><B
CLASS="COMMAND"
>lwresd</B
> [<TT
CLASS="OPTION"
>-C <TT
CLASS="REPLACEABLE"
><I
>config-file</I
></TT
></TT
>] [<TT
CLASS="OPTION"
>-d <TT
CLASS="REPLACEABLE"
><I
>debug-level</I
></TT
></TT
>] [<TT
CLASS="OPTION"
>-f</TT
>] [<TT
CLASS="OPTION"
>-g</TT
>] [<TT
CLASS="OPTION"
>-i <TT
CLASS="REPLACEABLE"
><I
>pid-file</I
></TT
></TT
>] [<TT
CLASS="OPTION"
>-n <TT
CLASS="REPLACEABLE"
><I
>#cpus</I
></TT
></TT
>] [<TT
CLASS="OPTION"
>-P <TT
CLASS="REPLACEABLE"
><I
>port</I
></TT
></TT
>] [<TT
CLASS="OPTION"
>-p <TT
CLASS="REPLACEABLE"
><I
>port</I
></TT
></TT
>] [<TT
CLASS="OPTION"
>-s</TT
>] [<TT
CLASS="OPTION"
>-t <TT
CLASS="REPLACEABLE"
><I
>directory</I
></TT
></TT
>] [<TT
CLASS="OPTION"
>-u <TT
CLASS="REPLACEABLE"
><I
>user</I
></TT
></TT
>] [<TT
CLASS="OPTION"
>-v</TT
>]</P
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN48"
></A
><H2
>DESCRIPTION</H2
><P
> <B
CLASS="COMMAND"
>lwresd</B
> 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.
</P
><P
> <B
CLASS="COMMAND"
>lwresd</B
> listens for resolver queries on a
UDP port on the IPv4 loopback interface, 127.0.0.1. This
means that <B
CLASS="COMMAND"
>lwresd</B
> 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.
</P
><P
> Incoming lightweight resolver requests are decoded by the
server which then resolves them using the DNS protocol. When
the DNS lookup completes, <B
CLASS="COMMAND"
>lwresd</B
> encodes
the answers in the lightweight resolver format and returns
them to the client that made the request.
</P
><P
> If <TT
CLASS="FILENAME"
> contains any
<TT
CLASS="OPTION"
>nameserver</TT
> entries, <B
CLASS="COMMAND"
>lwresd</B
>
sends recursive DNS queries to those servers. This is similar
to the use of forwarders in a caching name server. If no
<TT
CLASS="OPTION"
>nameserver</TT
> entries are present, or if
forwarding fails, <B
CLASS="COMMAND"
>lwresd</B
> resolves the
queries autonomously starting at the root name servers, using
a built-in list of root server hints.
</P
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN63"
></A
><H2
>OPTIONS</H2
><P
></P
><DIV
CLASS="VARIABLELIST"
><DL
><DT
>-C <TT
CLASS="REPLACEABLE"
><I
>config-file</I
></TT
></DT
><DD
><P
> Use <TT
CLASS="REPLACEABLE"
><I
>config-file</I
></TT
> as the
configuration file instead of the default,
<TT
CLASS="FILENAME"
>.
</P
></DD
><DT
>-d <TT
CLASS="REPLACEABLE"
><I
>debug-level</I
></TT
></DT
><DD
><P
> Set the daemon's debug level to <TT
CLASS="REPLACEABLE"
><I
>debug-level</I
></TT
>.
Debugging traces from <B
CLASS="COMMAND"
>lwresd</B
> become
more verbose as the debug level increases.
</P
></DD
><DT
>-f</DT
><DD
><P
> Run the server in the foreground (i.e. do not daemonize).
</P
></DD
><DT
>-g</DT
><DD
><P
> Run the server in the foreground and force all logging
to <TT
CLASS="FILENAME"
>stderr</TT
>.
</P
></DD
><DT
>-n <TT
CLASS="REPLACEABLE"
><I
>#cpus</I
></TT
></DT
><DD
><P
> Create <TT
CLASS="REPLACEABLE"
><I
>#cpus</I
></TT
> worker threads
to take advantage of multiple CPUs. If not specified,
<B
CLASS="COMMAND"
>lwresd</B
> 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.
</P
></DD
><DT
>-P <TT
CLASS="REPLACEABLE"
><I
>port</I
></TT
></DT
><DD
><P
> Listen for lightweight resolver queries on port
<TT
CLASS="REPLACEABLE"
><I
>port</I
></TT
>. If
not specified, the default is port 921.
</P
></DD
><DT
>-p <TT
CLASS="REPLACEABLE"
><I
>port</I
></TT
></DT
><DD
><P
> Send DNS lookups to port <TT
CLASS="REPLACEABLE"
><I
>port</I
></TT
>. 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.
</P
></DD
><DT
>-s</DT
><DD
><P
> Write memory usage statistics to <TT
CLASS="FILENAME"
>stdout</TT
> on exit.
</P
><DIV
CLASS="NOTE"
><BLOCKQUOTE
CLASS="NOTE"
><P
><B
>Note: </B
> This option is mainly of interest to BIND 9 developers
and may be removed or changed in a future release.
</P
></BLOCKQUOTE
></DIV
></DD
><DT
>-t <TT
CLASS="REPLACEABLE"
><I
>directory</I
></TT
></DT
><DD
><P
> <TT
CLASS="FUNCTION"
>chroot()</TT
> to <TT
CLASS="REPLACEABLE"
><I
>directory</I
></TT
> after
processing the command line arguments, but before
reading the configuration file.
</P
><DIV
CLASS="WARNING"
><P
></P
><TABLE
CLASS="WARNING"
BORDER="1"
WIDTH="90%"
><TR
><TD
ALIGN="CENTER"
><B
>Warning</B
></TD
></TR
><TR
><TD
ALIGN="LEFT"
><P
> This option should be used in conjunction with the
<TT
CLASS="OPTION"
>-u</TT
> option, as chrooting a process
running as root doesn't enhance security on most
systems; the way <TT
CLASS="FUNCTION"
>chroot()</TT
> is
defined allows a process with root privileges to
escape a chroot jail.
</P
></TD
></TR
></TABLE
></DIV
></DD
><DT
>-u <TT
CLASS="REPLACEABLE"
><I
>user</I
></TT
></DT
><DD
><P
> <TT
CLASS="FUNCTION"
>setuid()</TT
> to <TT
CLASS="REPLACEABLE"
><I
>user</I
></TT
> after completing
privileged operations, such as creating sockets that
listen on privileged ports.
</P
></DD
><DT
>-v</DT
><DD
><P
> Report the version number and exit.
</P
></DD
></DL
></DIV
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN137"
></A
><H2
>FILES</H2
><P
></P
><DIV
CLASS="VARIABLELIST"
><DL
><DT
><TT
CLASS="FILENAME"
></DT
><DD
><P
> The default configuration file.
</P
></DD
><DT
><TT
CLASS="FILENAME"
></DT
><DD
><P
> The default process-id file.
</P
></DD
></DL
></DIV
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN150"
></A
><H2
>SEE ALSO</H2
><P
> <SPAN
CLASS="CITEREFENTRY"
><SPAN
CLASS="REFENTRYTITLE"
>named</SPAN
>(8)</SPAN
>,
<SPAN
CLASS="CITEREFENTRY"
><SPAN
CLASS="REFENTRYTITLE"
>lwres</SPAN
>(3)</SPAN
>,
<SPAN
CLASS="CITEREFENTRY"
><SPAN
CLASS="REFENTRYTITLE"
>resolver</SPAN
>(5)</SPAN
>.
</P
></DIV
><DIV
CLASS="REFSECT1"
><A
NAME="AEN162"
></A
><H2
>AUTHOR</H2
><P
> Internet Software Consortium
</P
></DIV
></BODY
></HTML
>