Free Knowledge Resources


Linux Manual Pages


Free Software * Books

Source Code

Free Media

Linux

lwresd(8)


NAME

   lwresd - lightweight resolver daemon

SYNOPSIS

   lwresd [-c config-file] [-C config-file] [-d debug-level] [-f] [-g]
          [-i pid-file] [-m flag] [-n #cpus] [-P port] [-p port] [-s]
          [-t directory] [-u user] [-v] [-4] [-6]

DESCRIPTION

   lwresd 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.

   lwresd listens for resolver queries on a UDP port on the IPv4 loopback
   interface, 127.0.0.1. This means that lwresd 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.

   Incoming lightweight resolver requests are decoded by the server which
   then resolves them using the DNS protocol. When the DNS lookup
   completes, lwresd encodes the answers in the lightweight resolver
   format and returns them to the client that made the request.

   If /etc/resolv.conf contains any nameserver entries, lwresd sends
   recursive DNS queries to those servers. This is similar to the use of
   forwarders in a caching name server. If no nameserver entries are
   present, or if forwarding fails, lwresd resolves the queries
   autonomously starting at the root name servers, using a built-in list
   of root server hints.

OPTIONS

   -4
       Use IPv4 only even if the host machine is capable of IPv6.  -4 and
       -6 are mutually exclusive.

   -6
       Use IPv6 only even if the host machine is capable of IPv4.  -4 and
       -6 are mutually exclusive.

   -c config-file
       Use config-file as the configuration file instead of the default,
       /etc/lwresd.conf.  -c can not be used with -C.

   -C config-file
       Use config-file as the configuration file instead of the default,
       /etc/resolv.conf.  -C can not be used with -c.

   -d debug-level
       Set the daemon's debug level to debug-level. Debugging traces from
       lwresd become more verbose as the debug level increases.

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

   -g
       Run the server in the foreground and force all logging to stderr.

   -i pid-file
       Use pid-file as the PID file instead of the default,
       /var/run/lwresd/lwresd.pid.

   -m flag
       Turn on memory usage debugging flags. Possible flags are usage,
       trace, record, size, and mctx. These correspond to the
       ISC_MEM_DEBUGXXXX flags described in <isc/mem.h>.

   -n #cpus
       Create #cpus worker threads to take advantage of multiple CPUs. If
       not specified, lwresd 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 port
       Listen for lightweight resolver queries on port port. If not
       specified, the default is port 921.

   -p port
       Send DNS lookups to port port. 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.

   -s
       Write memory usage statistics to stdout on exit.
              Note: This option is mainly of interest to BIND 9 developers
              and may be removed or changed in a future release.

   -t directory
       Chroot to directory after processing the command line arguments,
       but before reading the configuration file.
              Warning: This option should be used in conjunction with the
              -u option, as chrooting a process running as root doesn't
              enhance security on most systems; the way chroot(2) is
              defined allows a process with root privileges to escape a
              chroot jail.

   -u user
       Setuid to user after completing privileged operations, such as
       creating sockets that listen on privileged ports.

   -v
       Report the version number and exit.

FILES

   /etc/resolv.conf
       The default configuration file.

   /var/run/lwresd.pid
       The default process-id file.

SEE ALSO

   named(8), lwres(3), resolver(5).

AUTHOR

   Internet Systems Consortium

COPYRIGHT

   Copyright  2004, 2005, 2007-2009, 2014 Internet Systems Consortium,
   Inc. ("ISC")
   Copyright  2000, 2001 Internet Software Consortium.



Opportunity


Personal Opportunity - Free software gives you access to billions of dollars of software at no cost. Use this software for your business, personal use or to develop a profitable skill. Access to source code provides access to a level of capabilities/information that companies protect though copyrights. Open source is a core component of the Internet and it is available to you. Leverage the billions of dollars in resources and capabilities to build a career, establish a business or change the world. The potential is endless for those who understand the opportunity.

Business Opportunity - Goldman Sachs, IBM and countless large corporations are leveraging open source to reduce costs, develop products and increase their bottom lines. Learn what these companies know about open source and how open source can give you the advantage.



Free Software


Free Software provides computer programs and capabilities at no cost but more importantly, it provides the freedom to run, edit, contribute to, and share the software. The importance of free software is a matter of access, not price. Software at no cost is a benefit but ownership rights to the software and source code is far more significant.

Free Office Software - The Libre Office suite provides top desktop productivity tools for free. This includes, a word processor, spreadsheet, presentation engine, drawing and flowcharting, database and math applications. Libre Office is available for Linux or Windows.



Free Books


The Free Books Library is a collection of thousands of the most popular public domain books in an online readable format. The collection includes great classical literature and more recent works where the U.S. copyright has expired. These books are yours to read and use without restrictions.

Source Code - Want to change a program or know how it works? Open Source provides the source code for its programs so that anyone can use, modify or learn how to write those programs themselves. Visit the GNU source code repositories to download the source.



Education


Study at Harvard, Stanford or MIT - Open edX provides free online courses from Harvard, MIT, Columbia, UC Berkeley and other top Universities. Hundreds of courses for almost all major subjects and course levels. Open edx also offers some paid courses and selected certifications.

Linux Manual Pages - A man or manual page is a form of software documentation found on Linux/Unix operating systems. Topics covered include computer programs (including library and system calls), formal standards and conventions, and even abstract concepts.


birds banner