1 .TH RESOLV+ 8 "August 19, 1992"
3 resolv+ - enhanced DNS resolver library
6 is a modified version of the standard Berkeley BIND host resolver library.
7 Enhancements include support for host lookups via the Internet Domain
10 file, and Sun's Network Information Service (NIS).
12 The programmer interface to the resolv+ routines is identical to that
13 of the standard resolver library. For further information see the
14 appropriate manual pages.
16 As with the standard resolver library, the file
18 must be set up before the resolver can function.
21 contains configuration information specific to resolv+.
25 file should contain one configuration keyword per line, followed
26 by appropriate configuration information. The keywords recognized are
33 Each keyword is described seperately below.
35 This keyword specifies how host lookups are to be performed. It should be
36 followed by one or more lookup methods, seperated by commas. Valid
43 This keyword may be listed more than once. Each time it should be followed
44 by a single domain name, with the leading dot. When set, the resolv+
45 library will automatically trim the given domain name from the end of
46 any hostname resolved via DNS. This is intended for use with local hosts
47 and domains. (Related note: trim will not affect hostnames gathered via
48 NIS or the hosts file. Care should be taken to insure that the first
49 hostname for each entry in the hosts file is fully qualified or non-qualified,
50 as appropriate for the local installation.)
56 If set to "on," the resolv+ library will return all valid addresses for
57 a host that appears in the
59 file, instead of only the first. This is off by default, as it may cause
60 a substantial performance loss at sites with large hosts files.
66 If set to "on," the resolv+ library will attempt to prevent hostname spoofing
67 to enhance the security of
71 It works as follows: after performing a host address lookup, resolv+ will
72 perform a hostname lookup for that address. If the two hostnames do not
73 match, the query will fail.
75 If this option is set to "on" and the
77 option is also set, resolv+ will log a warning of the error via the
79 facility. The default value is off.
85 If set to "on," resolv+ will attempt to reorder host addresses so that
86 local addresses (i.e., on the same subnet) are listed first when a
87 gethostbyname() is performed. Reordering is done for all lookup methods.
88 The default value is off.
89 .SH "ENVIRONMENT VARIABLES"
90 The following environment variables may be set to override resolv+'s
93 If set, it will override the default filename ("/etc/host.conf") for
94 the resolv+ configuration file.
96 If set, will override the "order" keyword in the host.conf file.
97 .IP RESOLV_SPOOF_CHECK
98 If set, will override the spoof check flag. Valid values are "off"
99 to disable checking, "warn" to enable checking and warning, and "warn off"
100 to enable checking but not warning.
101 .IP RESOLV_ADD_TRIM_DOMAINS
102 If set, contains a list of domains to trim that will augment, not
103 supersede, the list in the host.conf file.
104 .IP RESOLV_OVERRIDE_TRIM_DOMAINS
105 If set, contains a list of domains to trim that will override those
106 in the host.conf file.
108 If set, overrides the "multi" keyword in the host.conf file.
110 If set, overrides the "reorder" keyword in the host.conf file.
117 The original BIND resolver library comes from the University of California
118 at Berkeley's Computer Science Research Group. The original resolv+
119 modifications were made by Bill Wisner <wisner@uunet.UU.NET>. Bug fixes
120 and enhancements were contributed by Patrick Gosling, Chris Metcalf,
121 John DiMarco and J. Porter Clark, John P. Rouillard, Dan O'Neill and
124 resolver(3), resolver(5), hosts(5), hostname(7), named(8)