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17 <!-- Id: Bv9ARM.ch04.html,v 1.103 2009/11/11 01:14:42 tbox Exp -->
18 <html>
19 <head>
27 </head>
32 <tr>
37 </td>
38 </tr>
39 </table>
40 <hr>
41 </div>
47 <dl>
50 <dd><dl><dt><span class="sect2"><a href="Bv9ARM.ch04.html#journal">The journal file</a></span></dt></dl></dd>
51 <dt><span class="sect1"><a href="Bv9ARM.ch04.html#incremental_zone_transfers">Incremental Zone Transfers (IXFR)</a></span></dt>
53 <dd><dl><dt><span class="sect2"><a href="Bv9ARM.ch04.html#id2570654">Example split DNS setup</a></span></dt></dl></dd>
55 <dd><dl>
56 <dt><span class="sect2"><a href="Bv9ARM.ch04.html#id2571088">Generate Shared Keys for Each Pair of Hosts</a></span></dt>
57 <dt><span class="sect2"><a href="Bv9ARM.ch04.html#id2571229">Copying the Shared Secret to Both Machines</a></span></dt>
58 <dt><span class="sect2"><a href="Bv9ARM.ch04.html#id2571240">Informing the Servers of the Key's Existence</a></span></dt>
59 <dt><span class="sect2"><a href="Bv9ARM.ch04.html#id2571345">Instructing the Server to Use the Key</a></span></dt>
60 <dt><span class="sect2"><a href="Bv9ARM.ch04.html#id2571539">TSIG Key Based Access Control</a></span></dt>
62 </dl></dd>
66 <dd><dl>
70 </dl></dd>
71 <dt><span class="sect1"><a href="Bv9ARM.ch04.html#id2572061">IPv6 Support in <acronym class="acronym">BIND</acronym> 9</a></span></dt>
72 <dd><dl>
73 <dt><span class="sect2"><a href="Bv9ARM.ch04.html#id2572328">Address Lookups Using AAAA Records</a></span></dt>
74 <dt><span class="sect2"><a href="Bv9ARM.ch04.html#id2572349">Address to Name Lookups Using Nibble Format</a></span></dt>
75 </dl></dd>
76 </dl>
77 </div>
81 <p>
83 servers to notify their slave servers of changes to a zone's data. In
85 slave will check to see that its version of the zone is the
86 current version and, if not, initiate a zone transfer.
87 </p>
88 <p>
91 <span><strong class="command">notify</strong></span> option in <a href="Bv9ARM.ch06.html#boolean_options" title="Boolean Options">the section called “Boolean Options”</a> and
93 <a href="Bv9ARM.ch06.html#zone_transfers" title="Zone Transfers">the section called “Zone Transfers”</a>. The <span><strong class="command">NOTIFY</strong></span>
94 protocol is specified in RFC 1996.
95 </p>
98 As a slave zone can also be a master to other slaves, <span><strong class="command">named</strong></span>,
101 cause <span><strong class="command">named</strong></span> to only send <span><strong class="command">NOTIFY</strong></span> for master
102 zones that it loads.
103 </div>
104 </div>
108 <p>
109 Dynamic Update is a method for adding, replacing or deleting
110 records in a master server by sending it a special form of DNS
111 messages. The format and meaning of these messages is specified
112 in RFC 2136.
113 </p>
114 <p>
115 Dynamic update is enabled by including an
116 <span><strong class="command">allow-update</strong></span> or an <span><strong class="command">update-policy</strong></span>
118 </p>
119 <p>
124 See <a href="Bv9ARM.ch06.html#dynamic_update_policies" title="Dynamic Update Policies">the section called “Dynamic Update Policies”</a> for more details.
125 </p>
126 <p>
130 server to negotiate keys that can be matched against those
133 </p>
134 <p>
135 Updating of secure zones (zones using DNSSEC) follows RFC
136 3007: RRSIG, NSEC and NSEC3 records affected by updates are
137 automatically regenerated by the server using an online
138 zone key. Update authorization is based on transaction
139 signatures and an explicit server policy.
140 </p>
144 <p>
145 All changes made to a zone using dynamic update are stored
146 in the zone's journal file. This file is automatically created
147 by the server when the first dynamic update takes place.
148 The name of the journal file is formed by appending the extension
150 corresponding zone
151 file unless specifically overridden. The journal file is in a
152 binary format and should not be edited manually.
153 </p>
154 <p>
155 The server will also occasionally write ("dump")
156 the complete contents of the updated zone to its zone file.
157 This is not done immediately after
158 each dynamic update, because that would be too slow when a large
159 zone is updated frequently. Instead, the dump is delayed by
160 up to 15 minutes, allowing additional updates to take place.
161 During the dump process, transient files will be created
164 will be removed when the dump is complete, and can be safely
165 ignored.
166 </p>
167 <p>
168 When a server is restarted after a shutdown or crash, it will replay
169 the journal file to incorporate into the zone any updates that
170 took
171 place after the last zone dump.
172 </p>
173 <p>
174 Changes that result from incoming incremental zone transfers are
175 also
176 journalled in a similar way.
177 </p>
178 <p>
179 The zone files of dynamic zones cannot normally be edited by
180 hand because they are not guaranteed to contain the most recent
181 dynamic changes — those are only in the journal file.
182 The only way to ensure that the zone file of a dynamic zone
184 </p>
185 <p>
186 If you have to make changes to a dynamic zone
187 manually, the following procedure will work: Disable dynamic updates
188 to the zone using
189 <span><strong class="command">rndc freeze <em class="replaceable"><code>zone</code></em></strong></span>.
191 and update the master file. Edit the zone file. Run
192 <span><strong class="command">rndc thaw <em class="replaceable"><code>zone</code></em></strong></span>
193 to reload the changed zone and re-enable dynamic updates.
194 </p>
195 </div>
196 </div>
199 <a name="incremental_zone_transfers"></a>Incremental Zone Transfers (IXFR)</h2></div></div></div>
200 <p>
201 The incremental zone transfer (IXFR) protocol is a way for
202 slave servers to transfer only changed data, instead of having to
203 transfer the entire zone. The IXFR protocol is specified in RFC
205 </p>
206 <p>
208 supports IXFR for those zones
209 where the necessary change history information is available. These
210 include master zones maintained by dynamic update and slave zones
211 whose data was obtained by IXFR. For manually maintained master
212 zones, and for slave zones obtained by performing a full zone
213 transfer (AXFR), IXFR is supported only if the option
216 </p>
217 <p>
219 attempt to use IXFR unless
220 it is explicitly disabled. For more information about disabling
221 IXFR, see the description of the <span><strong class="command">request-ixfr</strong></span> clause
223 </p>
224 </div>
228 <p>
229 Setting up different views, or visibility, of the DNS space to
230 internal and external resolvers is usually referred to as a
232 reasons an organization would want to set up its DNS this way.
233 </p>
234 <p>
235 One common reason for setting up a DNS system this way is
237 Internet. There is some debate as to whether or not this is actually
238 useful.
239 Internal DNS information leaks out in many ways (via email headers,
240 for example) and most savvy "attackers" can find the information
241 they need using other means.
242 However, since listing addresses of internal servers that
243 external clients cannot possibly reach can result in
244 connection delays and other annoyances, an organization may
245 choose to use a Split DNS to present a consistent view of itself
246 to the outside world.
247 </p>
248 <p>
249 Another common reason for setting up a Split DNS system is
250 to allow internal networks that are behind filters or in RFC 1918
251 space (reserved IP space, as documented in RFC 1918) to resolve DNS
252 on the Internet. Split DNS can also be used to allow mail from outside
253 back in to the internal network.
254 </p>
258 <p>
261 has several corporate sites that have an internal network with
262 reserved
263 Internet Protocol (IP) space and an external demilitarized zone (DMZ),
264 or "outside" section of a network, that is available to the public.
265 </p>
266 <p>
268 to be able to resolve external hostnames and to exchange mail with
269 people on the outside. The company also wants its internal resolvers
270 to have access to certain internal-only zones that are not available
271 at all outside of the internal network.
272 </p>
273 <p>
274 In order to accomplish this, the company will set up two sets
275 of name servers. One set will be on the inside network (in the
276 reserved
277 IP space) and the other set will be on bastion hosts, which are
278 "proxy"
279 hosts that can talk to both sides of its network, in the DMZ.
280 </p>
281 <p>
282 The internal servers will be configured to forward all queries,
283 except queries for <code class="filename">site1.internal</code>, <code class="filename">site2.internal</code>, <code class="filename">site1.example.com</code>,
285 in the
286 DMZ. These internal servers will have complete sets of information
287 for <code class="filename">site1.example.com</code>, <code class="filename">site2.example.com</code>, <code class="filename">site1.internal</code>,
289 </p>
290 <p>
291 To protect the <code class="filename">site1.internal</code> and <code class="filename">site2.internal</code> domains,
292 the internal name servers must be configured to disallow all queries
293 to these domains from any external hosts, including the bastion
294 hosts.
295 </p>
296 <p>
297 The external servers, which are on the bastion hosts, will
298 be configured to serve the "public" version of the <code class="filename">site1</code> and <code class="filename">site2.example.com</code> zones.
299 This could include things such as the host records for public servers
300 (<code class="filename">www.example.com</code> and <code class="filename">ftp.example.com</code>),
301 and mail exchange (MX) records (<code class="filename">a.mx.example.com</code> and <code class="filename">b.mx.example.com</code>).
302 </p>
303 <p>
304 In addition, the public <code class="filename">site1</code> and <code class="filename">site2.example.com</code> zones
305 should have special MX records that contain wildcard (`*') records
306 pointing to the bastion hosts. This is needed because external mail
307 servers do not have any other way of looking up how to deliver mail
308 to those internal hosts. With the wildcard records, the mail will
309 be delivered to the bastion host, which can then forward it on to
310 internal hosts.
311 </p>
312 <p>
313 Here's an example of a wildcard MX record:
314 </p>
316 <p>
317 Now that they accept mail on behalf of anything in the internal
318 network, the bastion hosts will need to know how to deliver mail
319 to internal hosts. In order for this to work properly, the resolvers
320 on
321 the bastion hosts will need to be configured to point to the internal
322 name servers for DNS resolution.
323 </p>
324 <p>
325 Queries for internal hostnames will be answered by the internal
326 servers, and queries for external hostnames will be forwarded back
327 out to the DNS servers on the bastion hosts.
328 </p>
329 <p>
330 In order for all this to work properly, internal clients will
332 name servers for DNS queries. This could also be enforced via
333 selective
334 filtering on the network.
335 </p>
336 <p>
338 internal clients will now be able to:
339 </p>
341 <li>
343 and
345 </li>
346 <li>
349 </li>
352 </ul></div>
353 <p>
354 Hosts on the Internet will be able to:
355 </p>
357 <li>
359 and
361 </li>
362 <li>
365 </li>
366 </ul></div>
367 <p>
368 Here is an example configuration for the setup we just
369 described above. Note that this is only configuration information;
370 for information on how to configure your zone files, see <a href="Bv9ARM.ch03.html#sample_configuration" title="Sample Configurations">the section called “Sample Configurations”</a>.
371 </p>
372 <p>
373 Internal DNS server config:
374 </p>
381 options {
382 ...
383 ...
384 forward only;
385 // forward to external servers
386 forwarders {
388 };
389 // sample allow-transfer (no one)
390 allow-transfer { none; };
391 // restrict query access
392 allow-query { internals; externals; };
393 // restrict recursion
394 allow-recursion { internals; };
395 ...
396 ...
397 };
399 // sample master zone
400 zone "site1.example.com" {
401 type master;
402 file "m/site1.example.com";
403 // do normal iterative resolution (do not forward)
404 forwarders { };
405 allow-query { internals; externals; };
406 allow-transfer { internals; };
407 };
409 // sample slave zone
410 zone "site2.example.com" {
411 type slave;
412 file "s/site2.example.com";
413 masters { 172.16.72.3; };
414 forwarders { };
415 allow-query { internals; externals; };
416 allow-transfer { internals; };
417 };
419 zone "site1.internal" {
420 type master;
421 file "m/site1.internal";
422 forwarders { };
423 allow-query { internals; };
424 allow-transfer { internals; }
425 };
427 zone "site2.internal" {
428 type slave;
429 file "s/site2.internal";
430 masters { 172.16.72.3; };
431 forwarders { };
432 allow-query { internals };
433 allow-transfer { internals; }
434 };
435 </pre>
436 <p>
437 External (bastion host) DNS server config:
438 </p>
442 acl externals { bastion-ips-go-here; };
444 options {
445 ...
446 ...
447 // sample allow-transfer (no one)
448 allow-transfer { none; };
449 // default query access
450 allow-query { any; };
451 // restrict cache access
452 allow-query-cache { internals; externals; };
453 // restrict recursion
454 allow-recursion { internals; externals; };
455 ...
456 ...
457 };
459 // sample slave zone
460 zone "site1.example.com" {
461 type master;
462 file "m/site1.foo.com";
463 allow-transfer { internals; externals; };
464 };
466 zone "site2.example.com" {
467 type slave;
468 file "s/site2.foo.com";
469 masters { another_bastion_host_maybe; };
470 allow-transfer { internals; externals; }
471 };
472 </pre>
473 <p>
475 the bastion host(s):
476 </p>
478 search ...
479 nameserver 172.16.72.2
480 nameserver 172.16.72.3
481 nameserver 172.16.72.4
482 </pre>
483 </div>
484 </div>
488 <p>
489 This is a short guide to setting up Transaction SIGnatures
490 (TSIG) based transaction security in <acronym class="acronym">BIND</acronym>. It describes changes
491 to the configuration file as well as what changes are required for
492 different features, including the process of creating transaction
494 </p>
495 <p>
497 to server communication.
498 This includes zone transfer, notify, and recursive query messages.
499 Resolvers based on newer versions of <acronym class="acronym">BIND</acronym> 8 have limited support
500 for TSIG.
501 </p>
502 <p>
503 TSIG can also be useful for dynamic update. A primary
504 server for a dynamic zone should control access to the dynamic
505 update service, but IP-based access control is insufficient.
506 The cryptographic access control provided by TSIG
511 </p>
515 <p>
516 A shared secret is generated to be shared between <span class="emphasis"><em>host1</em></span> and <span class="emphasis"><em>host2</em></span>.
517 An arbitrary key name is chosen: "host1-host2.". The key name must
518 be the same on both hosts.
519 </p>
523 <p>
525 key as described above. Longer keys are better, but shorter keys
526 are easier to read. Note that the maximum key length is the digest
527 length, here 256 bits.
528 </p>
529 <p>
530 <strong class="userinput"><code>dnssec-keygen -a hmac-sha256 -b 128 -n HOST host1-host2.</code></strong>
531 </p>
532 <p>
534 Nothing directly uses this file, but the base-64 encoded string
536 can be extracted from the file and used as a shared secret:
537 </p>
539 <p>
541 be used as the shared secret.
542 </p>
543 </div>
547 <p>
548 The shared secret is simply a random sequence of bits, encoded
550 the length is a multiple of 4 and only valid characters are used),
551 so the shared secret can be manually generated.
552 </p>
553 <p>
554 Also, a known string can be run through <span><strong class="command">mmencode</strong></span> or
555 a similar program to generate base-64 encoded data.
556 </p>
557 </div>
558 </div>
562 <p>
563 This is beyond the scope of DNS. A secure transport mechanism
564 should be used. This could be secure FTP, ssh, telephone, etc.
565 </p>
566 </div>
570 <p>
571 Imagine <span class="emphasis"><em>host1</em></span> and <span class="emphasis"><em>host 2</em></span>
572 are
573 both servers. The following is added to each server's <code class="filename">named.conf</code> file:
574 </p>
576 key host1-host2. {
577 algorithm hmac-sha256;
578 secret "La/E5CjG9O+os1jq0a2jdA==";
579 };
580 </pre>
581 <p>
582 The secret is the one generated above. Since this is a secret, it
584 non-world readable, or the key directive be added to a non-world
586 </p>
587 <p>
588 At this point, the key is recognized. This means that if the
589 server receives a message signed by this key, it can verify the
590 signature. If the signature is successfully verified, the
591 response is signed by the same key.
592 </p>
593 </div>
597 <p>
598 Since keys are shared between two hosts only, the server must
599 be told when keys are to be used. The following is added to the <code class="filename">named.conf</code> file
600 for <span class="emphasis"><em>host1</em></span>, if the IP address of <span class="emphasis"><em>host2</em></span> is
601 10.1.2.3:
602 </p>
604 server 10.1.2.3 {
605 keys { host1-host2. ;};
606 };
607 </pre>
608 <p>
609 Multiple keys may be present, but only the first is used.
610 This directive does not contain any secrets, so it may be in a
611 world-readable
612 file.
613 </p>
614 <p>
616 to that address, the message will be signed with the specified key. <span class="emphasis"><em>host1</em></span> will
617 expect any responses to signed messages to be signed with the same
618 key.
619 </p>
620 <p>
622 configuration file (with <span class="emphasis"><em>host1</em></span>'s address) for <span class="emphasis"><em>host2</em></span> to
624 </p>
625 </div>
629 <p>
631 to be specified in ACL
632 definitions and
634 directives.
635 This has been extended to allow TSIG keys also. The above key would
637 </p>
638 <p>
640 </p>
642 allow-update { key host1-host2. ;};
643 </pre>
644 <p>
645 This allows dynamic updates to succeed only if the request
647 </p>
648 <p>
649 See <a href="Bv9ARM.ch06.html#dynamic_update_policies" title="Dynamic Update Policies">the section called “Dynamic Update Policies”</a> for a discussion of
651 </p>
652 </div>
656 <p>
657 The processing of TSIG signed messages can result in
658 several errors. If a signed message is sent to a non-TSIG aware
659 server, a FORMERR (format error) will be returned, since the server will not
660 understand the record. This is a result of misconfiguration,
661 since the server must be explicitly configured to send a TSIG
662 signed message to a specific server.
663 </p>
664 <p>
665 If a TSIG aware server receives a message signed by an
666 unknown key, the response will be unsigned with the TSIG
667 extended error code set to BADKEY. If a TSIG aware server
668 receives a message with a signature that does not validate, the
669 response will be unsigned with the TSIG extended error code set
670 to BADSIG. If a TSIG aware server receives a message with a time
671 outside of the allowed range, the response will be signed with
672 the TSIG extended error code set to BADTIME, and the time values
673 will be adjusted so that the response can be successfully
674 verified. In any of these cases, the message's rcode (response code) is set to
675 NOTAUTH (not authenticated).
676 </p>
677 </div>
678 </div>
683 is a mechanism for automatically generating a shared secret
684 between two hosts. There are several "modes" of
687 these modes, the Diffie-Hellman key exchange. Both hosts are
688 required to have a Diffie-Hellman KEY record (although this
689 record is not required to be present in a zone). The
691 signed either by TSIG or SIG(0). The result of
694 used to delete shared secrets that it had previously
695 generated.
696 </p>
697 <p>
699 client
701 query
702 (including any appropriate KEYs) to a TKEY-aware server. The
703 server response, if it indicates success, will contain a
705 After
706 this exchange, both participants have enough information to
707 determine the shared secret; the exact process depends on the
709 Diffie-Hellman
711 exchanged,
712 and the shared secret is derived by both participants.
713 </p>
714 </div>
718 <p>
721 SIG(0)
722 uses public/private keys to authenticate messages. Access control
723 is performed in the same manner as TSIG keys; privileges can be
724 granted or denied based on the key name.
725 </p>
726 <p>
727 When a SIG(0) signed message is received, it will only be
728 verified if the key is known and trusted by the server; the server
729 will not attempt to locate and/or validate the key.
730 </p>
731 <p>
732 SIG(0) signing of multiple-message TCP streams is not
733 supported.
734 </p>
735 <p>
738 </p>
739 </div>
743 <p>
744 Cryptographic authentication of DNS information is possible
747 This section describes the creation and use of DNSSEC signed zones.
748 </p>
749 <p>
750 In order to set up a DNSSEC secure zone, there are a series
752 9 ships
753 with several tools
754 that are used in this process, which are explained in more detail
756 full list of parameters. Note that the DNSSEC tools require the
757 keyset files to be in the working directory or the
759 that the tools shipped with BIND 9.2.x and earlier are not compatible
760 with the current ones.
761 </p>
762 <p>
763 There must also be communication with the administrators of
764 the parent and/or child zone to transmit keys. A zone's security
765 status must be indicated by the parent zone for a DNSSEC capable
766 resolver to trust its data. This is done through the presence
768 delegation
769 point.
770 </p>
771 <p>
772 For other servers to trust data in this zone, they must
773 either be statically configured with this zone's zone key or the
774 zone key of another zone above this one in the DNS tree.
775 </p>
779 <p>
781 generate keys.
782 </p>
783 <p>
784 A secure zone must contain one or more zone keys. The
785 zone keys will sign all other records in the zone, as well as
786 the zone keys of any secure delegated zones. Zone keys must
787 have the same name as the zone, a name type of
789 authentication.
790 It is recommended that zone keys use a cryptographic algorithm
791 designated as "mandatory to implement" by the IETF; currently
792 the only one is RSASHA1.
793 </p>
794 <p>
795 The following command will generate a 768-bit RSASHA1 key for
797 </p>
798 <p>
799 <strong class="userinput"><code>dnssec-keygen -a RSASHA1 -b 768 -n ZONE child.example.</code></strong>
800 </p>
801 <p>
802 Two output files will be produced:
805 (where
806 12345 is an example of a key tag). The key filenames contain
808 algorithm (3
810 this case).
812 file) is
813 used to generate signatures, and the public key (in the
815 verification.
816 </p>
817 <p>
818 To generate another key with the same properties (but with
819 a different key tag), repeat the above command.
820 </p>
821 <p>
823 to get a key pair from a crypto hardware and build the key
825 </p>
826 <p>
827 The public keys should be inserted into the zone file by
830 </p>
831 </div>
835 <p>
837 to sign a zone.
838 </p>
839 <p>
841 secure subzones should be present. The zone signer will
846 is not specified, then DS RRsets for the secure child
847 zones need to be added manually.
848 </p>
849 <p>
850 The following command signs the zone, assuming it is in a
852 default, all zone keys which have an available private key are
853 used to generate signatures.
854 </p>
855 <p>
856 <strong class="userinput"><code>dnssec-signzone -o child.example zone.child.example</code></strong>
857 </p>
858 <p>
859 One output file is produced:
861 file
863 as the
864 input file for the zone.
865 </p>
867 will also produce a keyset and dsset files and optionally a
868 dlvset file. These are used to provide the parent zone
871 secure entry point to the zone.
872 </p>
873 </div>
877 <p>
879 to DNS requests from DNSSEC aware clients,
881 (This is the default setting.)
882 </p>
883 <p>
888 and later), and at least one trust anchor must be configured
892 </p>
893 <p>
895 for zones that are used to form the first link in the
896 cryptographic chain of trust. All keys listed in
898 are deemed to exist and only the listed keys will be used
899 to validated the DNSKEY RRset that they are from.
900 </p>
901 <p>
903 automatically kept up to date via RFC 5011 trust anchor
904 maintenance.
905 </p>
906 <p>
909 later in this document.
910 </p>
911 <p>
913 9 does not verify signatures on load, so zone keys for
914 authoritative zones do not need to be specified in the
915 configuration file.
916 </p>
917 <p>
918 After DNSSEC gets established, a typical DNSSEC configuration
919 will look something like the following. It has one or
920 more public keys for the root. This allows answers from
921 outside the organization to be validated. It will also
922 have several keys for parts of the namespace the organization
924 is immune to compromises in the DNSSEC components of the security
925 of parent zones.
926 </p>
928 managed-keys {
929 /* Root Key */
931 JxrGkxJWoZu6I7PzJu/E9gx4UC1zGAHlXKdE4zYIpRh
932 aBKnvcC2U9mZhkdUpd1Vso/HAdjNe8LmMlnzY3zy2Xy
933 4klWOADTPzSv9eamj8V18PHGjBLaVtYvk/ln5ZApjYg
934 hf+6fElrmLkdaz MQ2OCnACR817DF4BBa7UR/beDHyp
935 5iWTXWSi6XmoJLbG9Scqc7l70KDqlvXR3M/lUUVRbke
936 g1IPJSidmK3ZyCllh4XSKbje/45SKucHgnwU5jefMtq
937 66gKodQj+MiA21AfUVe7u99WzTLzY3qlxDhxYQQ20FQ
938 97S+LKUTpQcq27R7AT3/V5hRQxScINqwcz4jYqZD2fQ
939 dgxbcDTClU0CRBdiieyLMNzXG3";
940 };
942 trusted-keys {
943 /* Key for our organization's forward zone */
945 5KbhTjrW1ZaARmPhEZZe3Y9ifgEuq7vZ/z
946 GZUdEGNWy+JZzus0lUptwgjGwhUS1558Hb
947 4JKUbbOTcM8pwXlj0EiX3oDFVmjHO444gL
948 kBOUKUf/mC7HvfwYH/Be22GnClrinKJp1O
949 g4ywzO9WglMk7jbfW33gUKvirTHr25GL7S
950 TQUzBb5Usxt8lgnyTUHs1t3JwCY5hKZ6Cq
951 FxmAVZP20igTixin/1LcrgX/KMEGd/biuv
952 F4qJCyduieHukuY3H4XMAcR+xia2nIUPvm
953 /oyWR8BW/hWdzOvnSCThlHf3xiYleDbt/o
954 1OTQ09A0=";
956 /* Key for our reverse zone. */
958 xOdNax071L18QqZnQQQAVVr+i
959 LhGTnNGp3HoWQLUIzKrJVZ3zg
960 gy3WwNT6kZo6c0tszYqbtvchm
961 gQC8CzKojM/W16i6MG/eafGU3
962 siaOdS0yOI6BgPsw+YZdzlYMa
963 IJGf4M4dyoKIhzdZyQ2bYQrjy
964 Q4LB0lC7aOnsMyYKHHYeRvPxj
965 IQXmdqgOJGq+vsevG06zW+1xg
966 YJh9rCIfnm1GX/KMgxLPG2vXT
967 D/RnLX+D3T3UL7HJYHJhAZD5L
968 59VvjSPsZJHeDCUyWYrvPZesZ
969 DIRvhDD52SKvbheeTJUm6Ehkz
970 ytNN2SN96QRk8j/iI8ib";
971 };
973 options {
974 ...
975 dnssec-enable yes;
976 dnssec-validation yes;
977 };
978 </pre>
981 None of the keys listed in this example are valid. In particular,
982 the root key is not valid.
983 </div>
984 <p>
985 When DNSSEC validation is enabled and properly configured,
986 the resolver will reject any answers from signed, secure zones
987 which fail to validate, and will return SERVFAIL to the client.
988 </p>
989 <p>
990 Responses may fail to validate for any of several reasons,
991 including missing, expired, or invalid signatures, a key which
992 does not match the DS RRset in the parent zone, or an insecure
993 response from a zone which, according to its parent, should have
994 been secure.
995 </p>
998 <p>
999 When the validator receives a response from an unsigned zone
1000 that has a signed parent, it must confirm with the parent
1001 that the zone was intentionally left unsigned. It does
1002 this by verifying, via signed and validated NSEC/NSEC3 records,
1003 that the parent zone contains no DS records for the child.
1004 </p>
1005 <p>
1007 is insecure, then the response is accepted. However, if it
1008 cannot, then it must assume an insecure response to be a
1009 forgery; it rejects the response and logs an error.
1010 </p>
1011 <p>
1012 The logged error reads "insecurity proof failed" and
1013 "got insecure response; parent indicates it should be secure".
1015 This referred to the zone, not the response.)
1016 </p>
1017 </div>
1018 </div>
1019 </div>
1022 <a name="id2572061"></a>IPv6 Support in <acronym class="acronym">BIND</acronym> 9</h2></div></div></div>
1023 <p>
1025 defined forms of IPv6 name to address and address to name
1026 lookups. It will also use IPv6 addresses to make queries when
1027 running on an IPv6 capable system.
1028 </p>
1029 <p>
1031 only AAAA records. RFC 3363 deprecated the use of A6 records,
1032 and client-side support for A6 records was accordingly removed
1035 load zone files containing A6 records correctly, answer queries
1036 for A6 records, and accept zone transfer for a zone containing A6
1037 records.
1038 </p>
1039 <p>
1041 the traditional "nibble" format used in the
1046 but support of binary labels has been completely removed per
1047 RFC 3363.
1049 the binary label format at all any more, and will return an
1050 error if given.
1052 name server will not load a zone file containing binary labels.
1053 </p>
1054 <p>
1055 For an overview of the format and structure of IPv6 addresses,
1056 see <a href="Bv9ARM.ch09.html#ipv6addresses" title="IPv6 addresses (AAAA)">the section called “IPv6 addresses (AAAA)”</a>.
1057 </p>
1061 <p>
1062 The IPv6 AAAA record is a parallel to the IPv4 A record,
1063 and, unlike the deprecated A6 record, specifies the entire
1064 IPv6 address in a single record. For example,
1065 </p>
1067 $ORIGIN example.com.
1069 </pre>
1070 <p>
1071 Use of IPv4-in-IPv6 mapped addresses is not recommended.
1072 If a host has an IPv4 address, use an A record, not
1074 the address.
1075 </p>
1076 </div>
1080 <p>
1081 When looking up an address in nibble format, the address
1082 components are simply reversed, just as in IPv4, and
1084 resulting name.
1085 For example, the following would provide reverse name lookup for
1086 a host with address
1088 </p>
1091 1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0 14400 IN PTR (
1092 host.example.com. )
1093 </pre>
1094 </div>
1095 </div>
1096 </div>
1098 <hr>
1100 <tr>
1105 </td>
1106 </tr>
1107 <tr>
1110 <td width="40%" align="right" valign="top"> Chapter 5. The <acronym class="acronym">BIND</acronym> 9 Lightweight Resolver</td>
1111 </tr>
1112 </table>
1113 </div>
1114 </body>
1115 </html>