lwresd

 

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LWRESD(8)                   System Manager's Manual                  LWRESD(8)

NAME
     lwresd - lightweight resolver daemon

SYNOPSIS
     lwresd [-C config-file] [-d debuglevel] [-f -g -s] [-i pid-file]
            [-n #cpus] [-P listen-port#] [-p port#] [-t directory]
            [-u user-id] [-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 pro­
     cesses 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 lwresd which then
     resolves them using the DNS protocol.  When the DNS lookup completes,
     lwresd encodes the answers from the name servers in the lightweight
     resolver format and returns them to the client that made the original
     request.

     If /etc/resolv.conf contains any nameserver entries, lwresd sends recur­
     sive DNS queries to those servers.  This is similar to the use of for­
     warders in a chaching name server.  If no nameserver entries are  pre­
     sent, or if forwarding fails, lwresd resolves the queries autonomously
     starting at the root name servers, using a compiled-in list of root
     servers hints.

     The options to lwresd are as follows:

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

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

     -f      run lwresd in the foreground.

     -g      run lwresd in the foreground and force all logging to stderr.

     -i      write the daemon's process id to pid-file instead of the default
             pathname.

     -n      create #cpus worker threads to take advantage of multiple CPUs.
             If no option is given, lwresd will try to determine the number of
             CPUs present and create one thread per CPU.  If lwresd is unable
             to determine the number of CPUs, a single worker thread is cre­
             ated.

     -P      listen for lightweight resolver queries on the loopback interface
             using UDP port port# instead of the default port number, 921.

     -p      send DNS lookups to port number listen-port# when querying name
             servers.  This provides a way of testing the lightweight resolver
             daemon with a name server that listens for queries on a non-stan­
             dard port number.

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

     -t      tells lwresd to chroot() to directory immediately after reading
             its configuration file.

     -u      run lwresd as user-id, which is a user name or numeric id that
             must be present in the password file.  The lightweight resolver
             daemon will change its user-id after it has carried out any priv­
             ileged operations, such as writing the process-id file or binding
             a socket to a privileged port (typically any port less than
             1024).

     -v      report the version number and exit.

FILES
     /etc/resolv.conf     default configuration file
     /var/run/lwresd.pid  default process-id file

SEE ALSO
     named(8), lwres(3).

NOTES
     lwresd is a daemon for lightweight resolvers, not a lightweight daemon
     for resolvers.

BIND9 9                          Jun 30, 2000                          BIND9 9

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