lwresd(8)

LWRESD(8)                     BIND9                     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.

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LWRESD(8)                     BIND9                     LWRESD(8)

     -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.
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     -t directory
         Chroot to directory after processing the command line
         arguments, but before reading the configuration file.

             Warning

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LWRESD(8)                     BIND9                     LWRESD(8)

             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.
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     -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, Inc.

COPYRIGHT

     Copyright 8c9 2004, 2005, 2007-2009, 2014-2016 Internet
     Systems Consortium, Inc. ("ISC")
     Copyright 8c9 2000, 2001 Internet Software Consortium.

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