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 re
solver format and returns them to the client that made the original re
quest.
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 creat
ed.
-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.
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 Jun 30, 2000 2
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