LWRESD(8)LWRESD(8)NAMElwresd - lightweight resolver daemon
SYNOPSISlwresd [ -C config-file ] [ -d debug-level ] [ -f ] [
-g ] [ -i pid-file ] [ -n #cpus ] [ -P port ] [ -p
port ] [ -s ] [ -t directory ] [ -u user ] [ -v ]
DESCRIPTIONlwresd 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 for-
warding 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 dae-
monize).
-g Run the server in the foreground and force all log-
ging 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 cre-
ated.
-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 configura-
tion 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 opera-
tions, 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 ALSOnamed(8), lwres(3), resolver(5).
AUTHOR
Internet Software Consortium
BIND9 June 30, 2000 LWRESD(8)
