1NSUPDATE(1)                          BIND9                         NSUPDATE(1)
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3
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NAME

6       nsupdate - Dynamic DNS update utility
7

SYNOPSIS

9       nsupdate [-d] [-D] [-i] [-L level] [[-g] | [-o] | [-l] |
10                [-y [hmac:]keyname:secret] | [-k keyfile]] [-t timeout]
11                [-u udptimeout] [-r udpretries] [-R randomdev] [-v] [-T] [-P]
12                [-V] [filename]
13

DESCRIPTION

15       nsupdate is used to submit Dynamic DNS Update requests as defined in
16       RFC 2136 to a name server. This allows resource records to be added or
17       removed from a zone without manually editing the zone file. A single
18       update request can contain requests to add or remove more than one
19       resource record.
20
21       Zones that are under dynamic control via nsupdate or a DHCP server
22       should not be edited by hand. Manual edits could conflict with dynamic
23       updates and cause data to be lost.
24
25       The resource records that are dynamically added or removed with
26       nsupdate have to be in the same zone. Requests are sent to the zone's
27       master server. This is identified by the MNAME field of the zone's SOA
28       record.
29
30       Transaction signatures can be used to authenticate the Dynamic DNS
31       updates. These use the TSIG resource record type described in RFC 2845
32       or the SIG(0) record described in RFC 2535 and RFC 2931 or GSS-TSIG as
33       described in RFC 3645.
34
35       TSIG relies on a shared secret that should only be known to nsupdate
36       and the name server. For instance, suitable key and server statements
37       would be added to /etc/named.conf so that the name server can associate
38       the appropriate secret key and algorithm with the IP address of the
39       client application that will be using TSIG authentication. You can use
40       ddns-confgen to generate suitable configuration fragments.  nsupdate
41       uses the -y or -k options to provide the TSIG shared secret. These
42       options are mutually exclusive.
43
44       SIG(0) uses public key cryptography. To use a SIG(0) key, the public
45       key must be stored in a KEY record in a zone served by the name server.
46
47       GSS-TSIG uses Kerberos credentials. Standard GSS-TSIG mode is switched
48       on with the -g flag. A non-standards-compliant variant of GSS-TSIG used
49       by Windows 2000 can be switched on with the -o flag.
50

OPTIONS

52       -d
53           Debug mode. This provides tracing information about the update
54           requests that are made and the replies received from the name
55           server.
56
57       -D
58           Extra debug mode.
59
60       -i
61           Force interactive mode, even when standard input is not a terminal.
62
63       -k keyfile
64           The file containing the TSIG authentication key. Keyfiles may be in
65           two formats: a single file containing a named.conf-format key
66           statement, which may be generated automatically by ddns-confgen, or
67           a pair of files whose names are of the format
68           K{name}.+157.+{random}.key and K{name}.+157.+{random}.private,
69           which can be generated by dnssec-keygen. The -k may also be used to
70           specify a SIG(0) key used to authenticate Dynamic DNS update
71           requests. In this case, the key specified is not an HMAC-MD5 key.
72
73       -l
74           Local-host only mode. This sets the server address to localhost
75           (disabling the server so that the server address cannot be
76           overridden). Connections to the local server will use a TSIG key
77           found in /var/run/named/session.key, which is automatically
78           generated by named if any local master zone has set update-policy
79           to local. The location of this key file can be overridden with the
80           -k option.
81
82       -L level
83           Set the logging debug level. If zero, logging is disabled.
84
85       -p port
86           Set the port to use for connections to a name server. The default
87           is 53.
88
89       -P
90           Print the list of private BIND-specific resource record types whose
91           format is understood by nsupdate. See also the -T option.
92
93       -r udpretries
94           The number of UDP retries. The default is 3. If zero, only one
95           update request will be made.
96
97       -R randomdev
98           Where to obtain randomness. If the operating system does not
99           provide a /dev/random or equivalent device, the default source of
100           randomness is keyboard input.  randomdev specifies the name of a
101           character device or file containing random data to be used instead
102           of the default. The special value keyboard indicates that keyboard
103           input should be used. This option may be specified multiple times.
104
105       -t timeout
106           The maximum time an update request can take before it is aborted.
107           The default is 300 seconds. Zero can be used to disable the
108           timeout.
109
110       -T
111           Print the list of IANA standard resource record types whose format
112           is understood by nsupdate.  nsupdate will exit after the lists are
113           printed. The -T option can be combined with the -P option.
114
115           Other types can be entered using "TYPEXXXXX" where "XXXXX" is the
116           decimal value of the type with no leading zeros. The rdata, if
117           present, will be parsed using the UNKNOWN rdata format,
118           (<backslash> <hash> <space> <length> <space> <hexstring>).
119
120       -u udptimeout
121           The UDP retry interval. The default is 3 seconds. If zero, the
122           interval will be computed from the timeout interval and number of
123           UDP retries.
124
125       -v
126           Use TCP even for small update requests. By default, nsupdate uses
127           UDP to send update requests to the name server unless they are too
128           large to fit in a UDP request in which case TCP will be used. TCP
129           may be preferable when a batch of update requests is made.
130
131       -V
132           Print the version number and exit.
133
134       -y [hmac:]keyname:secret
135           Literal TSIG authentication key.  keyname is the name of the key,
136           and secret is the base64 encoded shared secret.  hmac is the name
137           of the key algorithm; valid choices are hmac-md5, hmac-sha1,
138           hmac-sha224, hmac-sha256, hmac-sha384, or hmac-sha512. If hmac is
139           not specified, the default is hmac-md5 or if MD5 was disabled
140           hmac-sha256.
141
142           NOTE: Use of the -y option is discouraged because the shared secret
143           is supplied as a command line argument in clear text. This may be
144           visible in the output from ps(1) or in a history file maintained by
145           the user's shell.
146

INPUT FORMAT

148       nsupdate reads input from filename or standard input. Each command is
149       supplied on exactly one line of input. Some commands are for
150       administrative purposes. The others are either update instructions or
151       prerequisite checks on the contents of the zone. These checks set
152       conditions that some name or set of resource records (RRset) either
153       exists or is absent from the zone. These conditions must be met if the
154       entire update request is to succeed. Updates will be rejected if the
155       tests for the prerequisite conditions fail.
156
157       Every update request consists of zero or more prerequisites and zero or
158       more updates. This allows a suitably authenticated update request to
159       proceed if some specified resource records are present or missing from
160       the zone. A blank input line (or the send command) causes the
161       accumulated commands to be sent as one Dynamic DNS update request to
162       the name server.
163
164       The command formats and their meaning are as follows:
165
166       server {servername} [port]
167           Sends all dynamic update requests to the name server servername.
168           When no server statement is provided, nsupdate will send updates to
169           the master server of the correct zone. The MNAME field of that
170           zone's SOA record will identify the master server for that zone.
171           port is the port number on servername where the dynamic update
172           requests get sent. If no port number is specified, the default DNS
173           port number of 53 is used.
174
175       local {address} [port]
176           Sends all dynamic update requests using the local address. When no
177           local statement is provided, nsupdate will send updates using an
178           address and port chosen by the system.  port can additionally be
179           used to make requests come from a specific port. If no port number
180           is specified, the system will assign one.
181
182       zone {zonename}
183           Specifies that all updates are to be made to the zone zonename. If
184           no zone statement is provided, nsupdate will attempt determine the
185           correct zone to update based on the rest of the input.
186
187       class {classname}
188           Specify the default class. If no class is specified, the default
189           class is IN.
190
191       ttl {seconds}
192           Specify the default time to live for records to be added. The value
193           none will clear the default ttl.
194
195       key [hmac:] {keyname} {secret}
196           Specifies that all updates are to be TSIG-signed using the keyname
197           secret pair. If hmac is specified, then it sets the signing
198           algorithm in use; the default is hmac-md5 or if MD5 was disabled
199           hmac-sha256. The key command overrides any key specified on the
200           command line via -y or -k.
201
202       gsstsig
203           Use GSS-TSIG to sign the updated. This is equivalent to specifying
204           -g on the command line.
205
206       oldgsstsig
207           Use the Windows 2000 version of GSS-TSIG to sign the updated. This
208           is equivalent to specifying -o on the command line.
209
210       realm {[realm_name]}
211           When using GSS-TSIG use realm_name rather than the default realm in
212           krb5.conf. If no realm is specified the saved realm is cleared.
213
214       check-names {[yes_or_no]}
215           Turn on or off check-names processing on records to be added.
216           Check-names has no effect on prerequisites or records to be
217           deleted. By default check-names processing is on. If check-names
218           processing fails the record will not be added to the UPDATE
219           message.
220
221       [prereq] nxdomain {domain-name}
222           Requires that no resource record of any type exists with name
223           domain-name.
224
225       [prereq] yxdomain {domain-name}
226           Requires that domain-name exists (has as at least one resource
227           record, of any type).
228
229       [prereq] nxrrset {domain-name} [class] {type}
230           Requires that no resource record exists of the specified type,
231           class and domain-name. If class is omitted, IN (internet) is
232           assumed.
233
234       [prereq] yxrrset {domain-name} [class] {type}
235           This requires that a resource record of the specified type, class
236           and domain-name must exist. If class is omitted, IN (internet) is
237           assumed.
238
239       [prereq] yxrrset {domain-name} [class] {type} {data...}
240           The data from each set of prerequisites of this form sharing a
241           common type, class, and domain-name are combined to form a set of
242           RRs. This set of RRs must exactly match the set of RRs existing in
243           the zone at the given type, class, and domain-name. The data are
244           written in the standard text representation of the resource
245           record's RDATA.
246
247       [update] del[ete] {domain-name} [ttl] [class] [type [data...]]
248           Deletes any resource records named domain-name. If type and data is
249           provided, only matching resource records will be removed. The
250           internet class is assumed if class is not supplied. The ttl is
251           ignored, and is only allowed for compatibility.
252
253       [update] add {domain-name} {ttl} [class] {type} {data...}
254           Adds a new resource record with the specified ttl, class and data.
255
256       show
257           Displays the current message, containing all of the prerequisites
258           and updates specified since the last send.
259
260       send
261           Sends the current message. This is equivalent to entering a blank
262           line.
263
264       answer
265           Displays the answer.
266
267       debug
268           Turn on debugging.
269
270       version
271           Print version number.
272
273       help
274           Print a list of commands.
275
276       Lines beginning with a semicolon are comments and are ignored.
277

EXAMPLES

279       The examples below show how nsupdate could be used to insert and delete
280       resource records from the example.com zone. Notice that the input in
281       each example contains a trailing blank line so that a group of commands
282       are sent as one dynamic update request to the master name server for
283       example.com.
284
285           # nsupdate
286           > update delete oldhost.example.com A
287           > update add newhost.example.com 86400 A 172.16.1.1
288           > send
289
290       Any A records for oldhost.example.com are deleted. And an A record for
291       newhost.example.com with IP address 172.16.1.1 is added. The
292       newly-added record has a 1 day TTL (86400 seconds).
293
294           # nsupdate
295           > prereq nxdomain nickname.example.com
296           > update add nickname.example.com 86400 CNAME somehost.example.com
297           > send
298
299       The prerequisite condition gets the name server to check that there are
300       no resource records of any type for nickname.example.com. If there are,
301       the update request fails. If this name does not exist, a CNAME for it
302       is added. This ensures that when the CNAME is added, it cannot conflict
303       with the long-standing rule in RFC 1034 that a name must not exist as
304       any other record type if it exists as a CNAME. (The rule has been
305       updated for DNSSEC in RFC 2535 to allow CNAMEs to have RRSIG, DNSKEY
306       and NSEC records.)
307

FILES

309       /etc/resolv.conf
310           used to identify default name server
311
312       /var/run/named/session.key
313           sets the default TSIG key for use in local-only mode
314
315       K{name}.+157.+{random}.key
316           base-64 encoding of HMAC-MD5 key created by dnssec-keygen(8).
317
318       K{name}.+157.+{random}.private
319           base-64 encoding of HMAC-MD5 key created by dnssec-keygen(8).
320

SEE ALSO

322       RFC 2136, RFC 3007, RFC 2104, RFC 2845, RFC 1034, RFC 2535, RFC 2931,
323       named(8), ddns-confgen(8), dnssec-keygen(8).
324

BUGS

326       The TSIG key is redundantly stored in two separate files. This is a
327       consequence of nsupdate using the DST library for its cryptographic
328       operations, and may change in future releases.
329

AUTHOR

331       Internet Systems Consortium, Inc.
332
334       Copyright © 2000-2012, 2014-2021 Internet Systems Consortium, Inc.
335       ("ISC")
336
337
338
339ISC                               2014-04-18                       NSUPDATE(1)
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