1NSUPDATE(1) BIND 9 NSUPDATE(1)
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6 nsupdate - dynamic DNS update utility
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9 nsupdate [-d] [-D] [-i] [-L level] [ [-g] | [-o] | [-l] | [-y
10 [hmac:]keyname:secret] | [-k keyfile] ] [-t timeout] [-u udptimeout]
11 [-r udpretries] [-v] [-T] [-P] [-V] [ [-4] | [-6] ] [filename]
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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 re‐
18 source 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 nsup‐
25 date must be in the same zone. Requests are sent to the zone's primary
26 server, which is identified by the MNAME field of the zone's SOA
27 record.
28 Transaction signatures can be used to authenticate the Dynamic DNS up‐
30 dates. These use the TSIG resource record type described in RFC 2845,
31 the SIG(0) record described in RFC 2535 and RFC 2931, or GSS-TSIG as
32 described in RFC 3645.
33 TSIG relies on a shared secret that should only be known to nsupdate
35 and the name server. For instance, suitable key and server statements
36 are added to /etc/named.conf so that the name server can associate the
37 appropriate secret key and algorithm with the IP address of the client
38 application that is using TSIG authentication. ddns-confgen can gener‐
39 ate suitable configuration fragments. nsupdate uses the -y or -k op‐
40 tions to provide the TSIG shared secret; these options are mutually ex‐
41 clusive.
42 SIG(0) uses public key cryptography. To use a SIG(0) key, the public
44 key must be stored in a KEY record in a zone served by the name server.
45 GSS-TSIG uses Kerberos credentials. Standard GSS-TSIG mode is switched
47 on with the -g flag. A non-standards-compliant variant of GSS-TSIG used
48 by Windows 2000 can be switched on with the -o flag.
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51 -4 This option sets use of IPv4 only.
52 -6 This option sets use of IPv6 only.
54 -d This option sets debug mode, which provides tracing information
56 about the update requests that are made and the replies received
57 from the name server.
58 -D This option sets extra debug mode.
60 -i This option forces interactive mode, even when standard input is
62 not a terminal.
63 -k keyfile
65 This option indicates the file containing the TSIG authentica‐
66 tion key. Keyfiles may be in two formats: a single file contain‐
67 ing a named.conf-format key statement, which may be generated
68 automatically by ddns-confgen; or a pair of files whose names
69 are of the format K{name}.+157.+{random}.key and
70 K{name}.+157.+{random}.private, which can be generated by
71 dnssec-keygen. The -k option can also be used to specify a
72 SIG(0) key used to authenticate Dynamic DNS update requests. In
73 this case, the key specified is not an HMAC-MD5 key.
74 -l This option sets local-host only mode, which sets the server ad‐
76 dress to localhost (disabling the server so that the server ad‐
77 dress cannot be overridden). Connections to the local server use
78 a TSIG key found in /var/run/named/session.key, which is auto‐
79 matically generated by named if any local primary zone has set
80 update-policy to local. The location of this key file can be
81 overridden with the -k option.
82 -L level
84 This option sets the logging debug level. If zero, logging is
85 disabled.
86 -p port
88 This option sets the port to use for connections to a name
89 server. The default is 53.
90 -P This option prints the list of private BIND-specific resource
92 record types whose format is understood by nsupdate. See also
93 the -T option.
94 -r udpretries
96 This option sets the number of UDP retries. The default is 3. If
97 zero, only one update request is made.
98 -t timeout
100 This option sets the maximum time an update request can take be‐
101 fore it is aborted. The default is 300 seconds. If zero, the
102 timeout is disabled.
103 -T This option prints the list of IANA standard resource record
105 types whose format is understood by nsupdate. nsupdate exits af‐
106 ter the lists are printed. The -T option can be combined with
107 the -P option.
108 Other types can be entered using TYPEXXXXX where XXXXX is the
110 decimal value of the type with no leading zeros. The rdata, if
111 present, is parsed using the UNKNOWN rdata format, (<backslash>
112 <hash> <space> <length> <space> <hexstring>).
113 -u udptimeout
115 This option sets the UDP retry interval. The default is 3 sec‐
116 onds. If zero, the interval is computed from the timeout inter‐
117 val and number of UDP retries.
118 -v This option specifies that TCP should be used even for small up‐
120 date requests. By default, nsupdate uses UDP to send update re‐
121 quests to the name server unless they are too large to fit in a
122 UDP request, in which case TCP is used. TCP may be preferable
123 when a batch of update requests is made.
124 -V This option prints the version number and exits.
126 -y [hmac:]keyname:secret
128 This option sets the literal TSIG authentication key. keyname is
129 the name of the key, and secret is the base64 encoded shared se‐
130 cret. hmac is the name of the key algorithm; valid choices are
131 hmac-md5, hmac-sha1, hmac-sha224, hmac-sha256, hmac-sha384, or
132 hmac-sha512. If hmac is not specified, the default is hmac-md5,
133 or if MD5 was disabled, hmac-sha256.
134 NOTE: Use of the -y option is discouraged because the shared se‐
136 cret is supplied as a command-line argument in clear text. This
137 may be visible in the output from ps1 or in a history file main‐
138 tained by the user's shell.
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141 nsupdate reads input from filename or standard input. Each command is
142 supplied on exactly one line of input. Some commands are for adminis‐
143 trative purposes; others are either update instructions or prerequisite
144 checks on the contents of the zone. These checks set conditions that
145 some name or set of resource records (RRset) either exists or is absent
146 from the zone. These conditions must be met if the entire update re‐
147 quest is to succeed. Updates are rejected if the tests for the prereq‐
148 uisite conditions fail.
149 Every update request consists of zero or more prerequisites and zero or
151 more updates. This allows a suitably authenticated update request to
152 proceed if some specified resource records are either present or miss‐
153 ing from the zone. A blank input line (or the send command) causes the
154 accumulated commands to be sent as one Dynamic DNS update request to
155 the name server.
156 The command formats and their meanings are as follows:
158 server servername port
160 This command sends all dynamic update requests to the name
161 server servername. When no server statement is provided, nsup‐
162 date sends updates to the primary server of the correct zone.
163 The MNAME field of that zone's SOA record identify the primary
164 server for that zone. port is the port number on servername
165 where the dynamic update requests are sent. If no port number is
166 specified, the default DNS port number of 53 is used.
167 local address port
169 This command sends all dynamic update requests using the local
170 address. When no local statement is provided, nsupdate sends up‐
171 dates using an address and port chosen by the system. port can
172 also be used to force requests to come from a specific port. If
173 no port number is specified, the system assigns one.
174 zone zonename
176 This command specifies that all updates are to be made to the
177 zone zonename. If no zone statement is provided, nsupdate at‐
178 tempts to determine the correct zone to update based on the rest
179 of the input.
180 class classname
182 This command specifies the default class. If no class is speci‐
183 fied, the default class is IN.
184 ttl seconds
186 This command specifies the default time-to-live, in seconds, for
187 records to be added. The value none clears the default TTL.
188 key hmac:keyname secret
190 This command specifies that all updates are to be TSIG-signed
191 using the keyname-secret pair. If hmac is specified, it sets the
192 signing algorithm in use. The default is hmac-md5; if MD5 was
193 disabled, the default is hmac-sha256. The key command overrides
194 any key specified on the command line via -y or -k.
195 gsstsig
197 This command uses GSS-TSIG to sign the updates. This is equiva‐
198 lent to specifying -g on the command line.
199 oldgsstsig
201 This command uses the Windows 2000 version of GSS-TSIG to sign
202 the updates. This is equivalent to specifying -o on the command
203 line.
204 realm [realm_name]
206 When using GSS-TSIG, this command specifies the use of
207 realm_name rather than the default realm in krb5.conf. If no
208 realm is specified, the saved realm is cleared.
209 check-names [yes_or_no]
211 This command turns on or off check-names processing on records
212 to be added. Check-names has no effect on prerequisites or
213 records to be deleted. By default check-names processing is on.
214 If check-names processing fails, the record is not added to the
215 UPDATE message.
216 prereq nxdomain domain-name
218 This command requires that no resource record of any type exist
219 with the name domain-name.
220 prereq yxdomain domain-name
222 This command requires that domain-name exist (as at least one
223 resource record, of any type).
224 prereq nxrrset domain-name class type
226 This command requires that no resource record exist of the spec‐
227 ified type, class, and domain-name. If class is omitted, IN (In‐
228 ternet) is assumed.
229 prereq yxrrset domain-name class type
231 This command requires that a resource record of the specified
232 type, class and domain-name exist. If class is omitted, IN (in‐
233 ternet) is assumed.
234 prereq yxrrset domain-name class type data
236 With this command, the data from each set of prerequisites of
237 this form sharing a common type, class, and domain-name are com‐
238 bined to form a set of RRs. This set of RRs must exactly match
239 the set of RRs existing in the zone at the given type, class,
240 and domain-name. The data are written in the standard text rep‐
241 resentation of the resource record's RDATA.
242 update delete domain-name ttl class type data
244 This command deletes any resource records named domain-name. If
245 type and data are provided, only matching resource records are
246 removed. The Internet class is assumed if class is not sup‐
247 plied. The ttl is ignored, and is only allowed for compatibil‐
248 ity.
249 update add domain-name ttl class type data
251 This command adds a new resource record with the specified ttl,
252 class, and data.
253 show This command displays the current message, containing all of the
255 prerequisites and updates specified since the last send.
256 send This command sends the current message. This is equivalent to
258 entering a blank line.
259 answer This command displays the answer.
261 debug This command turns on debugging.
263 version
265 This command prints the version number.
266 help This command prints a list of commands.
268 Lines beginning with a semicolon (;) are comments and are ignored.
270
272 The examples below show how nsupdate can be used to insert and delete
273 resource records from the example.com zone. Notice that the input in
274 each example contains a trailing blank line, so that a group of com‐
275 mands is sent as one dynamic update request to the primary name server
276 for example.com.
277 # nsupdate
279 > update delete oldhost.example.com A
280 > update add newhost.example.com 86400 A 172.16.1.1
281 > send
282 Any A records for oldhost.example.com are deleted, and an A record for
284 newhost.example.com with IP address 172.16.1.1 is added. The newly
285 added record has a TTL of 1 day (86400 seconds).
286 # nsupdate
288 > prereq nxdomain nickname.example.com
289 > update add nickname.example.com 86400 CNAME somehost.example.com
290 > send
291 The prerequisite condition tells the name server to verify that there
293 are no resource records of any type for nickname.example.com. If there
294 are, the update request fails. If this name does not exist, a CNAME for
295 it is added. This ensures that when the CNAME is added, it cannot con‐
296 flict with the long-standing rule in RFC 1034 that a name must not ex‐
297 ist as any other record type if it exists as a CNAME. (The rule has
298 been updated for DNSSEC in RFC 2535 to allow CNAMEs to have RRSIG,
299 DNSKEY, and NSEC records.)
300
302 /etc/resolv.conf
303 Used to identify the default name server
304 /var/run/named/session.key
306 Sets the default TSIG key for use in local-only mode
307 K{name}.+157.+{random}.key
309 Base-64 encoding of the HMAC-MD5 key created by dnssec-keygen.
310 K{name}.+157.+{random}.private
312 Base-64 encoding of the HMAC-MD5 key created by dnssec-keygen.
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315 RFC 2136, RFC 3007, RFC 2104, RFC 2845, RFC 1034, RFC 2535, RFC 2931,
316 named(8), ddns-confgen(8), dnssec-keygen(8).
317
319 The TSIG key is redundantly stored in two separate files. This is a
320 consequence of nsupdate using the DST library for its cryptographic op‐
321 erations, and may change in future releases.
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324 Internet Systems Consortium
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327 2022, Internet Systems Consortium
3289.16.30-RH NSUPDATE(1)