1NSUPDATE(1) BIND9 NSUPDATE(1)
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6 nsupdate - Dynamic DNS update utility
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9 nsupdate [-d] [-D] [[-g] | [-o] | [-l] | [-y [hmac:]keyname:secret] |
10 [-k keyfile]] [-t timeout] [-u udptimeout] [-r udpretries]
11 [-R randomdev] [-v] [filename]
12
14 nsupdate is used to submit Dynamic DNS Update requests as defined in
15 RFC 2136 to a name server. This allows resource records to be added or
16 removed from a zone without manually editing the zone file. A single
17 update request can contain requests to add or remove more than one
18 resource record.
19 Zones that are under dynamic control via nsupdate or a DHCP server
21 should not be edited by hand. Manual edits could conflict with dynamic
22 updates and cause data to be lost.
23 The resource records that are dynamically added or removed with
25 nsupdate have to be in the same zone. Requests are sent to the zone's
26 master server. This is identified by the MNAME field of the zone's SOA
27 record.
28 The -d option makes nsupdate operate in debug mode. This provides
30 tracing information about the update requests that are made and the
31 replies received from the name server.
32 The -D option makes nsupdate report additional debugging information to
34 -d.
35 The -L option with an integer argument of zero or higher sets the
37 logging debug level. If zero, logging is disabled.
38 Transaction signatures can be used to authenticate the Dynamic DNS
40 updates. These use the TSIG resource record type described in RFC 2845
41 or the SIG(0) record described in RFC 2535 and RFC 2931 or GSS-TSIG as
42 described in RFC 3645. TSIG relies on a shared secret that should only
43 be known to nsupdate and the name server. Currently, the only supported
44 encryption algorithm for TSIG is HMAC-MD5, which is defined in RFC
45 2104. Once other algorithms are defined for TSIG, applications will
46 need to ensure they select the appropriate algorithm as well as the key
47 when authenticating each other. For instance, suitable key and server
48 statements would be added to /etc/named.conf so that the name server
49 can associate the appropriate secret key and algorithm with the IP
50 address of the client application that will be using TSIG
51 authentication. SIG(0) uses public key cryptography. To use a SIG(0)
52 key, the public key must be stored in a KEY record in a zone served by
53 the name server. nsupdate does not read /etc/named.conf.
54 GSS-TSIG uses Kerberos credentials. Standard GSS-TSIG mode is switched
56 on with the -g flag. A non-standards-compliant variant of GSS-TSIG used
57 by Windows 2000 can be switched on with the -o flag.
58 nsupdate uses the -y or -k option to provide the shared secret needed
60 to generate a TSIG record for authenticating Dynamic DNS update
61 requests, default type HMAC-MD5. These options are mutually exclusive.
62 When the -y option is used, a signature is generated from
64 [hmac:]keyname:secret. keyname is the name of the key, and secret is
65 the base64 encoded shared secret. Use of the -y option is discouraged
66 because the shared secret is supplied as a command line argument in
67 clear text. This may be visible in the output from ps(1) or in a
68 history file maintained by the user's shell.
69 With the -k option, nsupdate reads the shared secret from the file
71 keyfile. Keyfiles may be in two formats: a single file containing a
72 named.conf-format key statement, which may be generated automatically
73 by ddns-confgen, or a pair of files whose names are of the format
74 K{name}.+157.+{random}.key and K{name}.+157.+{random}.private, which
75 can be generated by dnssec-keygen. The -k may also be used to specify a
76 SIG(0) key used to authenticate Dynamic DNS update requests. In this
77 case, the key specified is not an HMAC-MD5 key.
78 nsupdate can be run in a local-host only mode using the -l flag. This
80 sets the server address to localhost (disabling the server so that the
81 server address cannot be overridden). Connections to the local server
82 will use a TSIG key found in /var/run/named/session.key, which is
83 automatically generated by named if any local master zone has set
84 update-policy to local. The location of this key file can be overridden
85 with the -k option.
86 By default, nsupdate uses UDP to send update requests to the name
88 server unless they are too large to fit in a UDP request in which case
89 TCP will be used. The -v option makes nsupdate use a TCP connection.
90 This may be preferable when a batch of update requests is made.
91 The -p sets the default port number to use for connections to a name
93 server. The default is 53.
94 The -t option sets the maximum time an update request can take before
96 it is aborted. The default is 300 seconds. Zero can be used to disable
97 the timeout.
98 The -u option sets the UDP retry interval. The default is 3 seconds. If
100 zero, the interval will be computed from the timeout interval and
101 number of UDP retries.
102 The -r option sets the number of UDP retries. The default is 3. If
104 zero, only one update request will be made.
105 The -R randomdev option specifies a source of randomness. If the
107 operating system does not provide a /dev/random or equivalent device,
108 the default source of randomness is keyboard input. randomdev
109 specifies the name of a character device or file containing random data
110 to be used instead of the default. The special value keyboard indicates
111 that keyboard input should be used. This option may be specified
112 multiple times.
113
115 nsupdate reads input from filename or standard input. Each command is
116 supplied on exactly one line of input. Some commands are for
117 administrative purposes. The others are either update instructions or
118 prerequisite checks on the contents of the zone. These checks set
119 conditions that some name or set of resource records (RRset) either
120 exists or is absent from the zone. These conditions must be met if the
121 entire update request is to succeed. Updates will be rejected if the
122 tests for the prerequisite conditions fail.
123 Every update request consists of zero or more prerequisites and zero or
125 more updates. This allows a suitably authenticated update request to
126 proceed if some specified resource records are present or missing from
127 the zone. A blank input line (or the send command) causes the
128 accumulated commands to be sent as one Dynamic DNS update request to
129 the name server.
130 The command formats and their meaning are as follows:
132 server {servername} [port]
134 Sends all dynamic update requests to the name server servername.
135 When no server statement is provided, nsupdate will send updates to
136 the master server of the correct zone. The MNAME field of that
137 zone's SOA record will identify the master server for that zone.
138 port is the port number on servername where the dynamic update
139 requests get sent. If no port number is specified, the default DNS
140 port number of 53 is used.
141 local {address} [port]
143 Sends all dynamic update requests using the local address. When no
144 local statement is provided, nsupdate will send updates using an
145 address and port chosen by the system. port can additionally be
146 used to make requests come from a specific port. If no port number
147 is specified, the system will assign one.
148 zone {zonename}
150 Specifies that all updates are to be made to the zone zonename. If
151 no zone statement is provided, nsupdate will attempt determine the
152 correct zone to update based on the rest of the input.
153 class {classname}
155 Specify the default class. If no class is specified, the default
156 class is IN.
157 ttl {seconds}
159 Specify the default time to live for records to be added. The value
160 none will clear the default ttl.
161 key {name} {secret}
163 Specifies that all updates are to be TSIG-signed using the keyname
164 keysecret pair. The key command overrides any key specified on the
165 command line via -y or -k.
166 gsstsig
168 Use GSS-TSIG to sign the updated. This is equivalent to specifying
169 -g on the commandline.
170 oldgsstsig
172 Use the Windows 2000 version of GSS-TSIG to sign the updated. This
173 is equivalent to specifying -o on the commandline.
174 realm {[realm_name]}
176 When using GSS-TSIG use realm_name rather than leaving the realm
177 detection up to GSSAPI. If no realm is specified the saved realm is
178 cleared.
179 [prereq] nxdomain {domain-name}
181 Requires that no resource record of any type exists with name
182 domain-name.
183 [prereq] yxdomain {domain-name}
185 Requires that domain-name exists (has as at least one resource
186 record, of any type).
187 [prereq] nxrrset {domain-name} [class] {type}
189 Requires that no resource record exists of the specified type,
190 class and domain-name. If class is omitted, IN (internet) is
191 assumed.
192 [prereq] yxrrset {domain-name} [class] {type}
194 This requires that a resource record of the specified type, class
195 and domain-name must exist. If class is omitted, IN (internet) is
196 assumed.
197 [prereq] yxrrset {domain-name} [class] {type} {data...}
199 The data from each set of prerequisites of this form sharing a
200 common type, class, and domain-name are combined to form a set of
201 RRs. This set of RRs must exactly match the set of RRs existing in
202 the zone at the given type, class, and domain-name. The data are
203 written in the standard text representation of the resource
204 record's RDATA.
205 [update] del[ete] {domain-name} [ttl] [class] [type [data...]]
207 Deletes any resource records named domain-name. If type and data is
208 provided, only matching resource records will be removed. The
209 internet class is assumed if class is not supplied. The ttl is
210 ignored, and is only allowed for compatibility.
211 [update] add {domain-name} {ttl} [class] {type} {data...}
213 Adds a new resource record with the specified ttl, class and data.
214 show
216 Displays the current message, containing all of the prerequisites
217 and updates specified since the last send.
218 send
220 Sends the current message. This is equivalent to entering a blank
221 line.
222 answer
224 Displays the answer.
225 debug
227 Turn on debugging.
228 Lines beginning with a semicolon are comments and are ignored.
230
232 The examples below show how nsupdate could be used to insert and delete
233 resource records from the example.com zone. Notice that the input in
234 each example contains a trailing blank line so that a group of commands
235 are sent as one dynamic update request to the master name server for
236 example.com.
237 # nsupdate
239 > update delete oldhost.example.com A
240 > update add newhost.example.com 86400 A 172.16.1.1
241 > send
242 Any A records for oldhost.example.com are deleted. And an A record for
245 newhost.example.com with IP address 172.16.1.1 is added. The
246 newly-added record has a 1 day TTL (86400 seconds).
247 # nsupdate
249 > prereq nxdomain nickname.example.com
250 > update add nickname.example.com 86400 CNAME somehost.example.com
251 > send
252 The prerequisite condition gets the name server to check that there are
255 no resource records of any type for nickname.example.com. If there are,
256 the update request fails. If this name does not exist, a CNAME for it
257 is added. This ensures that when the CNAME is added, it cannot conflict
258 with the long-standing rule in RFC 1034 that a name must not exist as
259 any other record type if it exists as a CNAME. (The rule has been
260 updated for DNSSEC in RFC 2535 to allow CNAMEs to have RRSIG, DNSKEY
261 and NSEC records.)
262
264 /etc/resolv.conf
265 used to identify default name server
266 /var/run/named/session.key
268 sets the default TSIG key for use in local-only mode
269 K{name}.+157.+{random}.key
271 base-64 encoding of HMAC-MD5 key created by dnssec-keygen(8).
272 K{name}.+157.+{random}.private
274 base-64 encoding of HMAC-MD5 key created by dnssec-keygen(8).
275
277 RFC 2136, RFC 3007, RFC 2104, RFC 2845, RFC 1034, RFC 2535, RFC 2931,
278 named(8), ddns-confgen(8), dnssec-keygen(8).
279
281 The TSIG key is redundantly stored in two separate files. This is a
282 consequence of nsupdate using the DST library for its cryptographic
283 operations, and may change in future releases.
284
286 Copyright © 2004-2012 Internet Systems Consortium, Inc. ("ISC")
287 Copyright © 2000-2003 Internet Software Consortium.
288BIND9 Aug 25, 2009 NSUPDATE(1)