File: resolv+.8

package info (click to toggle)
netbase 3.11-1.2
  • links: PTS
  • area: main
  • in suites: slink
  • size: 2,764 kB
  • ctags: 2,400
  • sloc: ansic: 25,540; sh: 1,090; makefile: 888; perl: 317
file content (124 lines) | stat: -rw-r--r-- 4,347 bytes parent folder | download | duplicates (4)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
.TH RESOLV+ 8 "August 19, 1992"
.SH NAME
resolv+ - enhanced DNS resolver library
.SH DESCRIPTION
.I Resolv+
is a modified version of the standard Berkeley BIND host resolver library.
Enhancements include support for host lookups via the Internet Domain
Name System (DNS), the
.IR /etc/hosts
file, and Sun's Network Information Service (NIS).
.PP
The programmer interface to the resolv+ routines is identical to that
of the standard resolver library.  For further information see the
appropriate manual pages.
.SH CONFIGURATION
As with the standard resolver library, the file
.IR /etc/resolv.conf
must be set up before the resolver can function.
In addition, the file
.IR /etc/host.conf
contains configuration information specific to resolv+.
.PP
The
.IR host.conf
file should contain one configuration keyword per line, followed
by appropriate configuration information.  The keywords recognized are
.I order ,
.I trim ,
.I multi ,
.I nospoof ,
and
.I reorder .
Each keyword is described seperately below.
.IP order
This keyword specifies how host lookups are to be performed.  It should be
followed by one or more lookup methods, seperated by commas.  Valid
methods are
.I bind ,
.I hosts
and
.I nis .
.IP trim
This keyword may be listed more than once.  Each time it should be followed
by a single domain name, with the leading dot.  When set, the resolv+
library will automatically trim the given domain name from the end of
any hostname resolved via DNS.  This is intended for use with local hosts
and domains.  (Related note: trim will not affect hostnames gathered via
NIS or the hosts file.  Care should be taken to insure that the first
hostname for each entry in the hosts file is fully qualified or non-qualified,
as appropriate for the local installation.)
.IP multi
Valid values are
.I on
and
.I off .
If set to "on," the resolv+ library will return all valid addresses for
a host that appears in the
.IR /etc/hosts
file, instead of only the first.  This is off by default, as it may cause
a substantial performance loss at sites with large hosts files.
.IP nospoof
Valid values are
.I on
and
.I off .
If set to "on," the resolv+ library will attempt to prevent hostname spoofing
to enhance the security of
.IR rlogin
and
.IR rsh .
It works as follows: after performing a host address lookup, resolv+ will
perform a hostname lookup for that address.  If the two hostnames do not
match, the query will fail.
.IP alert
If this option is set to "on" and the
.I nospoof
option is also set, resolv+ will log a warning of the error via the
.IR syslog
facility.  The default value is off.
.IP reorder
Valid values are
.I on
and
.I off .
If set to "on," resolv+ will attempt to reorder host addresses so that
local addresses (i.e., on the same subnet) are listed first when a
gethostbyname() is performed.  Reordering is done for all lookup methods.
The default value is off.
.SH "ENVIRONMENT VARIABLES"
The following environment variables may be set to override resolv+'s
configured behavior:
.IP RESOLV_HOST_CONF
If set, it will override the default filename ("/etc/host.conf") for
the resolv+ configuration file.
.IP RESOLV_SERV_ORDER
If set, will override the "order" keyword in the host.conf file.
.IP RESOLV_SPOOF_CHECK
If set, will override the spoof check flag.  Valid values are "off"
to disable checking, "warn" to enable checking and warning, and "warn off"
to enable checking but not warning.
.IP RESOLV_ADD_TRIM_DOMAINS
If set, contains a list of domains to trim that will augment, not
supersede, the list in the host.conf file.
.IP RESOLV_OVERRIDE_TRIM_DOMAINS
If set, contains a list of domains to trim that will override those
in the host.conf file.
.IP RESOLV_MULTI
If set, overrides the "multi" keyword in the host.conf file.
.IP RESOLV_REORDER
If set, overrides the "reorder" keyword in the host.conf file.
.SH FILES
/etc/host.conf,
/etc/hosts
.SH BUGS
Quite possibly.
.SH AUTHOR
The original BIND resolver library comes from the University of California
at Berkeley's Computer Science Research Group.  The original resolv+
modifications were made by Bill Wisner <wisner@uunet.UU.NET>.  Bug fixes
and enhancements were contributed by Patrick Gosling, Chris Metcalf,
John DiMarco and J. Porter Clark, John P. Rouillard, Dan O'Neill and
Tom Limoncelli.
.SH "SEE ALSO"
resolver(3), resolver(5), hosts(5), hostname(7), named(8)