lwresd



LWRESD(8)                                                            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 direc-
       tory ]  [ -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 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 the server which
       then resolves them using the DNS protocol. When  the  DNS  lookup  com-
       pletes,  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 argu-
              ments, 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)

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