1LWRESD(8) BIND9 LWRESD(8)
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6 lwresd - lightweight resolver daemon
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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]]
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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.
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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.
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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.
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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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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.
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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).
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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.
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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.
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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.
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88 -s
89 Write memory usage statistics to stdout on exit.
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91 Note
92 This option is mainly of interest to BIND 9 developers and may
93 be removed or changed in a future release.
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95 -t directory
96 Chroot to directory after processing the command line arguments,
97 but before reading the configuration file.
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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.
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105 -u user
106 Setuid to user after completing privileged operations, such as
107 creating sockets that listen on privileged ports.
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109 -v
110 Report the version number and exit.
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113 /etc/resolv.conf
114 The default configuration file.
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116 /var/run/lwresd.pid
117 The default process-id file.
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120 named(8), lwres(3), resolver(5).
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123 Internet Systems Consortium, Inc.
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126 Copyright © 2000, 2001, 2004, 2005, 2007-2009, 2014-2019 Internet
127 Systems Consortium, Inc. ("ISC")
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131ISC 2009-01-20 LWRESD(8)