NAME
lwresd — lightweight resolver daemon
SYNOPSIS
lwresd
[-fgs]
[-C
config-file]
[-d
debuglevel]
[-i
pid-file]
[-n
ncpus]
[-P
query-port]
[-p
port]
[-t
directory]
[-u
user-id]
DESCRIPTION
The
lwresd
daemon provides name lookup services for 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
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 the
/etc/resolv.conf
configuration file 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 compiled-in list of root-server hints.
Options
- -C config-file
Use
config-file
as the configuration file.
The default is
/etc/resolv.conf.
- -d debuglevel
Set the 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 standard error.
- -i pid-file
Write the daemon's process ID to
pid-file.
The default is
/var/run/lwresd.pid.
- -n ncpus
Create
ncpus
worker threads to take advantage of multiple CPUs.
By default,
lwresd
tries to determine the number of CPUs present
and creates one thread per CPU.
If it cannot determine the number of CPUs,
it creates a single worker thread.
- -P query-port
Send DNS lookups to port number
query-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 nonstandard port number.
- -p port
Listen for lightweight resolver queries on the
loopback interface using UDP port number
port.
The default is port 921.
- -s
Write memory usage statistics to standard output on exit.
This option is only of interest to BIND 9 developers and may be
removed or changed in a future release.
- -t directory
Change root to
directory
immediately after reading the configuration file
(see
chroot(2)).
- -u user-id
Run as
user-id,
which is a user name or numeric ID
that must be present in the password file.
lwresd
changes its
user-id
after it has carried out any privileged operations,
such as writing the process-ID file
or binding a socket to a privileged port
(typically any port less than 1024).
Note
lwresd
is a daemon for lightweight resolvers,
not a lightweight daemon for resolvers.
AUTHOR
lwresd
was developed by the Internet Systems Consortium (ISC).
FILES
- /etc/resolv.conf
Default resolver configuration file
- /var/run/lwresd.pid
Default process-id file
SEE ALSO
named(1M),
chroot(2).
HP-UX IP Address and Client Management Administrator's Guide,
available online at
http://docs.hp.com.
BIND 9 Administrator Reference Manual,
available from the Internet Systems Consortium at
http://www.isc.org/sw/bind/arm93.
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