LWRESD(8)                     BIND9                     LWRESD(8)



NAME
       lwresd - lightweight resolver daemon

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

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
       -C config-file
              Use config-file as the configuration file instead
              of the default, /etc/resolv.conf.

       -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.

       -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() 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



BIND9                     June 30, 2000                 LWRESD(8)