1RESOLVCONF(8) BSD System Manager's Manual RESOLVCONF(8)
2
4 resolvconf — a framework for managing multiple DNS configurations
5
7 resolvconf -I
8 resolvconf [-m metric] [-p] [-x] -a interface[.protocol] <file
9 resolvconf -C pattern
10 resolvconf -c pattern
11 resolvconf [-f] -d interface[.protocol]
12 resolvconf [-x] -il pattern
13 resolvconf -u
14 resolvconf --version
15
17 resolvconf manages resolv.conf(5) files from multiple sources, such as
18 DHCP and VPN clients. Traditionally, the host runs just one client and
19 that updates /etc/resolv.conf. More modern systems frequently have wired
20 and wireless interfaces and there is no guarantee both are on the same
21 network. With the advent of VPN and other types of networking daemons,
22 many things now contend for the contents of /etc/resolv.conf.
23 resolvconf solves this by letting the daemon send their resolv.conf(5)
25 file to resolvconf via stdin(4) with the argument -a interface[.protocol]
26 instead of the filesystem. resolvconf then updates /etc/resolv.conf as
27 it thinks best. When a local resolver other than libc is installed, such
28 as dnsmasq(8) or named(8), then resolvconf will supply files that the
29 resolver should be configured to include.
30 resolvconf assumes it has a job to do. In some situations resolvconf
32 needs to act as a deterrent to writing to /etc/resolv.conf. Where this
33 file cannot be made immutable or you just need to toggle this behaviour,
34 resolvconf can be disabled by adding resolvconf=NO to resolvconf.conf(5).
35 resolvconf can mark an interfaces resolv.conf as private. This means
37 that the name servers listed in that resolv.conf are only used for
38 queries against the domain/search listed in the same file. This only
39 works when a local resolver other than libc is installed. See
40 resolvconf.conf(5) for how to configure resolvconf to use a local name
41 server and how to remove the private marking.
42 resolvconf can mark an interfaces resolv.conf as exclusive. Only the
44 latest exclusive interface is used for processing, otherwise all are.
45 When an interface goes down, it should then call resolvconf with -d
47 interface.* arguments to delete the resolv.conf file(s) for all the
48 protocols on the interface. For systems that support the concept of per‐
49 sisting configuration when the carrier goes down, then it should instead
50 call resolvconf with -C interface.* arguments to deprecate the matching
51 interfaces and -c interface.* to activate the matching interfaces when
52 the carrier comes up. This only affects the order in which interfaces
53 are processed.
54 Here are some options for the above commands:-
56 -f Ignore non existent interfaces. Only really useful for
58 deleting interfaces.
59 -m metric Set the metric of the interface when adding it, default of
61 0. Lower metrics take precedence. This affects the default
62 order of interfaces when listed.
63 -p Marks the interface resolv.conf as private.
65 -x Mark the interface resolv.conf as exclusive when adding,
67 otherwise only use the latest exclusive interface.
68 resolvconf has some more commands for general usage:-
70 -i pattern List the interfaces and protocols, optionally matching
72 pattern, we have resolv.conf files for.
73 -l pattern List the resolv.conf files we have. If pattern is specified
75 then we list the files for the interfaces and protocols that
76 match it.
77 -u Force resolvconf to update all its subscribers. resolvconf
79 does not update the subscribers when adding a resolv.conf
80 that matches what it already has for that interface.
81 --version Echo the resolvconf version to stdout.
83 resolvconf also has some commands designed to be used by it's subscribers
85 and system startup:-
86 -I Initialise the state directory /run/resolvconf. This only
88 needs to be called if the initial system boot sequence does
89 not automatically clean it out; for example the state direc‐
90 tory is moved somewhere other than /var/run. If used, it
91 should only be called once as early in the system boot
92 sequence as possible and before resolvconf is used to add
93 interfaces.
94 -R Echo the command used to restart a service.
96 -r service If the service is running then restart it. If the service
98 does not exist or is not running then zero is returned, oth‐
99 erwise the result of restarting the service.
100 -v Echo variables DOMAINS, SEARCH and NAMESERVERS so that the
102 subscriber can configure the resolver easily.
103 -V Same as -v except that only the information configured in
105 resolvconf.conf(5) is set.
106
108 For resolvconf to work effectively, it has to process the resolv.confs
109 for the interfaces in the correct order. resolvconf first processes
110 interfaces from the interface_order list, then interfaces without a metic
111 and that match the dynamic_order list, then interfaces with a metric in
112 order and finally the rest in the operating systems lexical order. See
113 resolvconf.conf(5) for details on these lists.
114
116 Here are some suggested protocol tags to use for each resolv.conf file
117 registered on an interface:-
118 dhcp Dynamic Host Configuration Protocol. Initial versions of
120 resolvconf did not recommend a protocol tag be appended to
121 the interface name. When the protocol is absent, it is
122 assumed to be the DHCP protocol.
123 ppp Point-to-Point Protocol.
125 ra IPv6 Router Advertisement.
127 dhcp6 Dynamic Host Configuration Protocol, version 6.
129
131 If a subscriber has the executable bit then it is executed otherwise it
132 is assumed to be a shell script and sourced into the current environment
133 in a subshell. This is done so that subscribers can remain fast, but are
134 also not limited to the shell language.
135 Portable subscribers should not use anything outside of /bin and /sbin
137 because /usr and others may not be available when booting. Also, it
138 would be unwise to assume any shell specific features.
139
141 IF_METRIC
142 If the -m option is not present then we use IF_METRIC for the metric.
143 IF_PRIVATE
145 Marks the interface resolv.conf as private.
146 IF_EXCLUSIVE
148 Marks the interface resolv.conf as exclusive.
149
151 /etc/resolv.conf.bak
152 Backup file of the original resolv.conf.
153 /etc/resolvconf.conf
155 Configuration file for resolvconf.
156 /usr/lib/resolvconf
158 Directory of subscribers which are run every time resolvconf adds,
159 deletes or updates.
160 /usr/lib/resolvconf/libc.d
162 Directory of subscribers which are run after the libc subscriber is run.
163 /run/resolvconf
165 State directory for resolvconf.
166
168 resolver(3), stdin(4), resolv.conf(5), resolvconf.conf(5)
169
171 This implementation of resolvconf is called openresolv and is fully com‐
172 mand line compatible with Debian's resolvconf, as written by Thomas Hood.
173
175 Roy Marples <roy@marples.name>
176
178 Please report them to
179 http://roy.marples.name/projects/openresolv
180 resolvconf does not validate any of the files given to it.
182 When running a local resolver other than libc, you will need to configure
184 it to include files that resolvconf will generate. You should consult
185 resolvconf.conf(5) for instructions on how to configure your resolver.
186BSD December 23, 2016 BSD