1LWRESD(8)                            BIND9                           LWRESD(8)
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NAME

6       lwresd - lightweight resolver daemon
7

SYNOPSIS

9       lwresd [-c config-file] [-C config-file] [-d debug-level] [-f] [-g]
10              [-i pid-file] [-m flag] [-n #cpus] [-P port] [-p port] [-s]
11              [-t directory] [-u user] [-v] [[-4] | [-6]]
12

DESCRIPTION

14       lwresd is the daemon providing name lookup services to clients that use
15       the BIND 9 lightweight resolver library. It is essentially a
16       stripped-down, caching-only name server that answers queries using the
17       BIND 9 lightweight resolver protocol rather than the DNS protocol.
18
19       lwresd listens for resolver queries on a UDP port on the IPv4 loopback
20       interface, 127.0.0.1. This means that lwresd can only be used by
21       processes running on the local machine. By default, UDP port number 921
22       is used for lightweight resolver requests and responses.
23
24       Incoming lightweight resolver requests are decoded by the server which
25       then resolves them using the DNS protocol. When the DNS lookup
26       completes, lwresd encodes the answers in the lightweight resolver
27       format and returns them to the client that made the request.
28
29       If /etc/resolv.conf contains any nameserver entries, lwresd sends
30       recursive DNS queries to those servers. This is similar to the use of
31       forwarders in a caching name server. If no nameserver entries are
32       present, or if forwarding fails, lwresd resolves the queries
33       autonomously starting at the root name servers, using a built-in list
34       of root server hints.
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OPTIONS

37       -4
38           Use IPv4 only even if the host machine is capable of IPv6.  -4 and
39           -6 are mutually exclusive.
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41       -6
42           Use IPv6 only even if the host machine is capable of IPv4.  -4 and
43           -6 are mutually exclusive.
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45       -c config-file
46           Use config-file as the configuration file instead of the default,
47           /etc/lwresd.conf.  -c can not be used with -C.
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49       -C config-file
50           Use config-file as the configuration file instead of the default,
51           /etc/resolv.conf.  -C can not be used with -c.
52
53       -d debug-level
54           Set the daemon's debug level to debug-level. Debugging traces from
55           lwresd become more verbose as the debug level increases.
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57       -f
58           Run the server in the foreground (i.e. do not daemonize).
59
60       -g
61           Run the server in the foreground and force all logging to stderr.
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63       -i pid-file
64           Use pid-file as the PID file instead of the default,
65           /var/run/lwresd/lwresd.pid.
66
67       -m flag
68           Turn on memory usage debugging flags. Possible flags are usage,
69           trace, record, size, and mctx. These correspond to the
70           ISC_MEM_DEBUGXXXX flags described in <isc/mem.h>.
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72       -n #cpus
73           Create #cpus worker threads to take advantage of multiple CPUs. If
74           not specified, lwresd will try to determine the number of CPUs
75           present and create one thread per CPU. If it is unable to determine
76           the number of CPUs, a single worker thread will be created.
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78       -P port
79           Listen for lightweight resolver queries on port port. If not
80           specified, the default is port 921.
81
82       -p port
83           Send DNS lookups to port port. If not specified, the default is
84           port 53. This provides a way of testing the lightweight resolver
85           daemon with a name server that listens for queries on a
86           non-standard port number.
87
88       -s
89           Write memory usage statistics to stdout on exit.
90
91               Note
92               This option is mainly of interest to BIND 9 developers and may
93               be removed or changed in a future release.
94
95       -t directory
96           Chroot to directory after processing the command line arguments,
97           but before reading the configuration file.
98
99               Warning
100               This option should be used in conjunction with the -u option,
101               as chrooting a process running as root doesn't enhance security
102               on most systems; the way chroot(2) is defined allows a process
103               with root privileges to escape a chroot jail.
104
105       -u user
106           Setuid to user after completing privileged operations, such as
107           creating sockets that listen on privileged ports.
108
109       -v
110           Report the version number and exit.
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FILES

113       /etc/resolv.conf
114           The default configuration file.
115
116       /var/run/lwresd.pid
117           The default process-id file.
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SEE ALSO

120       named(8), lwres(3), resolver(5).
121

AUTHOR

123       Internet Systems Consortium, Inc.
124

126       Copyright © 2000, 2001, 2004, 2005, 2007-2009, 2014-2021 Internet
127       Systems Consortium, Inc. ("ISC")
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131ISC                               2009-01-20                         LWRESD(8)
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