382N/A - Copyright (C) 2004-2012 Internet Systems Consortium, Inc. ("ISC") 382N/A - Copyright (C) 2000-2003 Internet Software Consortium. 382N/A - Permission to use, copy, modify, and/or distribute this software for any 382N/A - purpose with or without fee is hereby granted, provided that the above 382N/A - copyright notice and this permission notice appear in all copies. 382N/A - THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH 382N/A - REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY 382N/A - AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT, 382N/A - INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM 382N/A - LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE 382N/A - OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR 382N/A - PERFORMANCE OF THIS SOFTWARE. 382N/A<
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1431N/A<
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1431N/A<
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382N/A<
th width="60%" align="center">�</
th>
1431N/A<
div class="chapter" lang="en">
1431N/A<
div class="titlepage"><
div><
div><
h2 class="title">
382N/A<
a name="Bv9ARM.ch04"></
a>Chapter�4.�Advanced DNS Features</
h2></
div></
div></
div>
1431N/A<
p><
b>Table of Contents</
b></
p>
1431N/A<
dd><
dl><
dt><
span class="sect2"><
a href="Bv9ARM.ch04.html#journal">The journal file</
a></
span></
dt></
dl></
dd>
1431N/A<
dt><
span class="sect1"><
a href="Bv9ARM.ch04.html#incremental_zone_transfers">Incremental Zone Transfers (IXFR)</
a></
span></
dt>
382N/A<
dd><
dl><
dt><
span class="sect2"><
a href="Bv9ARM.ch04.html#id2571285">Example split DNS setup</
a></
span></
dt></
dl></
dd>
873N/A<
dt><
span class="sect2"><
a href="Bv9ARM.ch04.html#id2564004">Generate Shared Keys for Each Pair of Hosts</
a></
span></
dt>
873N/A<
dt><
span class="sect2"><
a href="Bv9ARM.ch04.html#id2564077">Copying the Shared Secret to Both Machines</
a></
span></
dt>
873N/A<
dt><
span class="sect2"><
a href="Bv9ARM.ch04.html#id2564088">Informing the Servers of the Key's Existence</
a></
span></
dt>
873N/A<
dt><
span class="sect2"><
a href="Bv9ARM.ch04.html#id2564124">Instructing the Server to Use the Key</
a></
span></
dt>
873N/A<
dt><
span class="sect2"><
a href="Bv9ARM.ch04.html#id2572169">TSIG Key Based Access Control</
a></
span></
dt>
1431N/A<
dt><
span class="sect2"><
a href="Bv9ARM.ch04.html#id2609234">Converting from insecure to secure</
a></
span></
dt>
873N/A<
dt><
span class="sect2"><
a href="Bv9ARM.ch04.html#id2563569">Fully automatic zone signing</
a></
span></
dt>
873N/A<
dt><
span class="sect2"><
a href="Bv9ARM.ch04.html#id2571837">NSEC3PARAM rollovers via UPDATE</
a></
span></
dt>
873N/A<
dt><
span class="sect2"><
a href="Bv9ARM.ch04.html#id2571847">Converting from NSEC to NSEC3</
a></
span></
dt>
873N/A<
dt><
span class="sect2"><
a href="Bv9ARM.ch04.html#id2571857">Converting from NSEC3 to NSEC</
a></
span></
dt>
873N/A<
dt><
span class="sect2"><
a href="Bv9ARM.ch04.html#id2571869">Converting from secure to insecure</
a></
span></
dt>
1431N/A<
dt><
span class="sect2"><
a href="Bv9ARM.ch04.html#id2636556">Specifying the engine on the command line</
a></
span></
dt>
873N/A<
dt><
span class="sect2"><
a href="Bv9ARM.ch04.html#id2636670">Running named with automatic zone re-signing</
a></
span></
dt>
873N/A<
dt><
span class="sect1"><
a href="Bv9ARM.ch04.html#dlz-info">DLZ (Dynamically Loadable Zones)</
a></
span></
dt>
873N/A<
dt><
span class="sect1"><
a href="Bv9ARM.ch04.html#id2573006">IPv6 Support in <
acronym class="acronym">BIND</
acronym> 9</
a></
span></
dt>
873N/A<
dt><
span class="sect2"><
a href="Bv9ARM.ch04.html#id2573068">Address Lookups Using AAAA Records</
a></
span></
dt>
873N/A<
dt><
span class="sect2"><
a href="Bv9ARM.ch04.html#id2573090">Address to Name Lookups Using Nibble Format</
a></
span></
dt>
873N/A<
div class="sect1" lang="en">
873N/A<
div class="titlepage"><
div><
div><
h2 class="title" style="clear: both">
873N/A<
a name="notify"></
a>Notify</
h2></
div></
div></
div>
873N/A <
acronym class="acronym">DNS</
acronym> NOTIFY is a mechanism that allows master
873N/A servers to notify their slave servers of changes to a zone's data. In
1431N/A response to a <
span><
strong class="command">NOTIFY</
strong></
span> from a master server, the
1431N/A slave will check to see that its version of the zone is the
1431N/A current version and, if not, initiate a zone transfer.
1431N/A For more information about <
acronym class="acronym">DNS</
acronym>
1431N/A <
span><
strong class="command">NOTIFY</
strong></
span>, see the description of the
1431N/A <
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
1431N/A the description of the zone option <
span><
strong class="command">also-notify</
strong></
span> in
1431N/A <
a href="Bv9ARM.ch06.html#zone_transfers" title="Zone Transfers">the section called “Zone Transfers”</
a>. The <
span><
strong class="command">NOTIFY</
strong></
span>
1431N/A protocol is specified in RFC 1996.
1431N/A<
div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
1431N/A As a slave zone can also be a master to other slaves, <
span><
strong class="command">named</
strong></
span>,
873N/A by default, sends <
span><
strong class="command">NOTIFY</
strong></
span> messages for every zone
873N/A it loads. Specifying <
span><
strong class="command">notify master-only;</
strong></
span> will
873N/A cause <
span><
strong class="command">named</
strong></
span> to only send <
span><
strong class="command">NOTIFY</
strong></
span> for master
873N/A<
div class="sect1" lang="en">
873N/A<
div class="titlepage"><
div><
div><
h2 class="title" style="clear: both">
873N/A<
a name="dynamic_update"></
a>Dynamic Update</
h2></
div></
div></
div>
873N/A Dynamic Update is a method for adding, replacing or deleting
873N/A records in a master server by sending it a special form of DNS
873N/A messages. The format and meaning of these messages is specified
873N/A Dynamic update is enabled by including an
873N/A <
span><
strong class="command">allow-update</
strong></
span> or an <
span><
strong class="command">update-policy</
strong></
span>
873N/A clause in the <
span><
strong class="command">zone</
strong></
span> statement.
1431N/A If the zone's <
span><
strong class="command">update-policy</
strong></
span> is set to
1431N/A <
strong class="userinput"><
code>local</
code></
strong>, updates to the zone
1431N/A will be permitted for the key <
code class="varname">local-ddns</
code>,
1431N/A which will be generated by <
span><
strong class="command">named</
strong></
span> at startup.
1431N/A See <
a href="Bv9ARM.ch06.html#dynamic_update_policies" title="Dynamic Update Policies">the section called “Dynamic Update Policies”</
a> for more details.
1431N/A Dynamic updates using Kerberos signed requests can be made
1431N/A <
span><
strong class="command">tkey-gssapi-keytab</
strong></
span> option, or alternatively
1431N/A by setting both the <
span><
strong class="command">tkey-gssapi-credential</
strong></
span>
1431N/A and <
span><
strong class="command">tkey-domain</
strong></
span> options. Once enabled,
1431N/A Kerberos signed requests will be matched against the update
382N/A policies for the zone, using the Kerberos principal as the
873N/A signer for the request.
1431N/A Updating of secure zones (zones using DNSSEC) follows RFC
1431N/A 3007: RRSIG, NSEC and NSEC3 records affected by updates are
1431N/A automatically regenerated by the server using an online
1507N/A zone key. Update authorization is based on transaction
1431N/A signatures and an explicit server policy.
1542N/A<
div class="sect2" lang="en">
1475N/A<
div class="titlepage"><
div><
div><
h3 class="title">
873N/A<
a name="journal"></
a>The journal file</
h3></
div></
div></
div>
1431N/A All changes made to a zone using dynamic update are stored
1431N/A in the zone's journal file. This file is automatically created
1431N/A by the server when the first dynamic update takes place.
1431N/A The name of the journal file is formed by appending the extension
1431N/A <
code class="filename">.jnl</
code> to the name of the
873N/A file unless specifically overridden. The journal file is in a
1431N/A binary format and should not be edited manually.
1431N/A The server will also occasionally write ("dump")
1475N/A the complete contents of the updated zone to its zone file.
1431N/A This is not done immediately after
1431N/A each dynamic update, because that would be too slow when a large
1431N/A zone is updated frequently. Instead, the dump is delayed by
1431N/A up to 15 minutes, allowing additional updates to take place.
1431N/A During the dump process, transient files will be created
1431N/A with the extensions <
code class="filename">.jnw</
code> and
1431N/A <
code class="filename">.jbk</
code>; under ordinary circumstances, these
1431N/A will be removed when the dump is complete, and can be safely
1431N/A When a server is restarted after a shutdown or crash, it will replay
1431N/A the journal file to incorporate into the zone any updates that
1431N/A place after the last zone dump.
1507N/A Changes that result from incoming incremental zone transfers are
1452N/A journalled in a similar way.
1431N/A The zone files of dynamic zones cannot normally be edited by
1431N/A hand because they are not guaranteed to contain the most recent
1431N/A dynamic changes — those are only in the journal file.
1431N/A The only way to ensure that the zone file of a dynamic zone
1431N/A is up to date is to run <
span><
strong class="command">rndc stop</
strong></
span>.
1431N/A If you have to make changes to a dynamic zone
1431N/A manually, the following procedure will work: Disable dynamic updates
1431N/A <
span><
strong class="command">rndc freeze <
em class="replaceable"><
code>zone</
code></
em></
strong></
span>.
1431N/A This will also remove the zone's <
code class="filename">.jnl</
code> file
1431N/A and update the master file. Edit the zone file. Run
1431N/A <
span><
strong class="command">rndc thaw <
em class="replaceable"><
code>zone</
code></
em></
strong></
span>
1431N/A to reload the changed zone and re-enable dynamic updates.
1431N/A<
div class="sect1" lang="en">
1431N/A<
div class="titlepage"><
div><
div><
h2 class="title" style="clear: both">
1431N/A<
a name="incremental_zone_transfers"></
a>Incremental Zone Transfers (IXFR)</
h2></
div></
div></
div>
1431N/A The incremental zone transfer (IXFR) protocol is a way for
1431N/A slave servers to transfer only changed data, instead of having to
1431N/A transfer the entire zone. The IXFR protocol is specified in RFC
1431N/A When acting as a master, <
acronym class="acronym">BIND</
acronym> 9
1431N/A supports IXFR for those zones
1431N/A where the necessary change history information is available. These
1431N/A include master zones maintained by dynamic update and slave zones
1431N/A whose data was obtained by IXFR. For manually maintained master
1431N/A zones, and for slave zones obtained by performing a full zone
1431N/A transfer (AXFR), IXFR is supported only if the option
1431N/A <
span><
strong class="command">ixfr-from-differences</
strong></
span> is set
1431N/A to <
strong class="userinput"><
code>yes</
code></
strong>.
1431N/A When acting as a slave, <
acronym class="acronym">BIND</
acronym> 9 will
1431N/A it is explicitly disabled. For more information about disabling
1431N/A IXFR, see the description of the <
span><
strong class="command">request-ixfr</
strong></
span> clause
1431N/A of the <
span><
strong class="command">server</
strong></
span> statement.
1431N/A<
div class="sect1" lang="en">
1431N/A<
div class="titlepage"><
div><
div><
h2 class="title" style="clear: both">
1431N/A<
a name="id2571267"></
a>Split DNS</
h2></
div></
div></
div>
1431N/A Setting up different views, or visibility, of the DNS space to
1431N/A internal and external resolvers is usually referred to as a
1431N/A <
span class="emphasis"><
em>Split DNS</
em></
span> setup. There are several
1431N/A reasons an organization would want to set up its DNS this way.
1431N/A One common reason for setting up a DNS system this way is
1431N/A to hide "internal" DNS information from "external" clients on the
1431N/A Internet. There is some debate as to whether or not this is actually
1431N/A Internal DNS information leaks out in many ways (via email headers,
1431N/A for example) and most savvy "attackers" can find the information
1431N/A they need using other means.
1431N/A However, since listing addresses of internal servers that
1431N/A external clients cannot possibly reach can result in
1431N/A connection delays and other annoyances, an organization may
1431N/A choose to use a Split DNS to present a consistent view of itself
1431N/A Another common reason for setting up a Split DNS system is
1431N/A to allow internal networks that are behind filters or in RFC 1918
1431N/A space (reserved IP space, as documented in RFC 1918) to resolve DNS
1431N/A on the Internet. Split DNS can also be used to allow mail from outside
1431N/A back in to the internal network.
1431N/A<
div class="sect2" lang="en">
1431N/A<
div class="titlepage"><
div><
div><
h3 class="title">
1431N/A<
a name="id2571285"></
a>Example split DNS setup</
h3></
div></
div></
div>
1431N/A Let's say a company named <
span class="emphasis"><
em>Example, Inc.</
em></
span>
1431N/A has several corporate sites that have an internal network with
1431N/A Internet Protocol (IP) space and an external demilitarized zone (DMZ),
1431N/A or "outside" section of a network, that is available to the public.
1431N/A <
span class="emphasis"><
em>Example, Inc.</
em></
span> wants its internal clients
1431N/A to be able to resolve external hostnames and to exchange mail with
1431N/A people on the outside. The company also wants its internal resolvers
1431N/A to have access to certain internal-only zones that are not available
1431N/A at all outside of the internal network.
1431N/A In order to accomplish this, the company will set up two sets
1431N/A of name servers. One set will be on the inside network (in the
1431N/A IP space) and the other set will be on bastion hosts, which are
1431N/A hosts that can talk to both sides of its network, in the DMZ.
1431N/A The internal servers will be configured to forward all queries,
1431N/A DMZ. These internal servers will have complete sets of information
1431N/A the internal name servers must be configured to disallow all queries
1431N/A to these domains from any external hosts, including the bastion
1431N/A The external servers, which are on the bastion hosts, will
1431N/A be configured to serve the "public" version of the <
code class="filename">site1</
code> and <
code class="filename">
site2.example.com</
code> zones.
1431N/A This could include things such as the host records for public servers
1431N/A In addition, the public <
code class="filename">site1</
code> and <
code class="filename">
site2.example.com</
code> zones
1431N/A should have special MX records that contain wildcard (`*') records
1431N/A pointing to the bastion hosts. This is needed because external mail
1431N/A servers do not have any other way of looking up how to deliver mail
1431N/A to those internal hosts. With the wildcard records, the mail will
1431N/A be delivered to the bastion host, which can then forward it on to
1431N/A Here's an example of a wildcard MX record:
1431N/A Now that they accept mail on behalf of anything in the internal
1431N/A network, the bastion hosts will need to know how to deliver mail
1431N/A to internal hosts. In order for this to work properly, the resolvers
1431N/A the bastion hosts will need to be configured to point to the internal
1431N/A name servers for DNS resolution.
1431N/A Queries for internal hostnames will be answered by the internal
1431N/A servers, and queries for external hostnames will be forwarded back
1431N/A out to the DNS servers on the bastion hosts.
1431N/A In order for all this to work properly, internal clients will
1431N/A need to be configured to query <
span class="emphasis"><
em>only</
em></
span> the internal
1431N/A name servers for DNS queries. This could also be enforced via
1431N/A If everything has been set properly, <
span class="emphasis"><
em>Example, Inc.</
em></
span>'s
1431N/A internal clients will now be able to:
1490N/A<
div class="itemizedlist"><
ul type="disc">
1490N/A Look up any hostnames in the <
code class="literal">site1</
code>
1490N/A<
li>Look up any hostnames on the Internet.</
li>
1431N/A<
li>Exchange mail with both internal and external people.</
li>
1490N/A Hosts on the Internet will be able to:
1490N/A<
div class="itemizedlist"><
ul type="disc">
1490N/A Look up any hostnames in the <
code class="literal">site1</
code>
1431N/A Exchange mail with anyone in the <
code class="literal">site1</
code> and
1490N/A Here is an example configuration for the setup we just
1431N/A described above. Note that this is only configuration information;
1431N/A 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>.
1431N/A Internal DNS server config:
1431N/A<
pre class="programlisting">
1431N/Aacl externals { <
code class="varname">bastion-ips-go-here</
code>; };
1431N/A // forward to external servers
1431N/A <
code class="varname">bastion-ips-go-here</
code>;
1431N/A // sample allow-transfer (no one)
1431N/A allow-query { internals; externals; };
1431N/A allow-recursion { internals; };
1431N/A // do normal iterative resolution (do not forward)
1431N/A allow-query { internals; externals; };
1431N/A allow-transfer { internals; };
1472N/A allow-query { internals; externals; };
1431N/A allow-transfer { internals; };
1431N/A allow-query { internals; };
1431N/A allow-transfer { internals; }
1431N/A allow-transfer { internals; }
1431N/A External (bastion host) DNS server config:
1431N/A<
pre class="programlisting">
1431N/Aacl externals { bastion-ips-go-here; };
1431N/A // sample allow-transfer (no one)
1431N/A allow-query-cache { internals; externals; };
1472N/A allow-recursion { internals; externals; };
1431N/A allow-transfer { internals; externals; };
1431N/A masters { another_bastion_host_maybe; };
1472N/A allow-transfer { internals; externals; }
1431N/A<
pre class="programlisting">
1431N/A<
div class="sect1" lang="en">
1431N/A<
div class="titlepage"><
div><
div><
h2 class="title" style="clear: both">
1431N/A<
a name="tsig"></
a>TSIG</
h2></
div></
div></
div>
1431N/A This is a short guide to setting up Transaction SIGnatures
1431N/A (TSIG) based transaction security in <
acronym class="acronym">BIND</
acronym>. It describes changes
1431N/A to the configuration file as well as what changes are required for
1431N/A different features, including the process of creating transaction
1736N/A keys and using transaction signatures with <
acronym class="acronym">BIND</
acronym>.
1431N/A <
acronym class="acronym">BIND</
acronym> primarily supports TSIG for server
1736N/A This includes zone transfer, notify, and recursive query messages.
1736N/A Resolvers based on newer versions of <
acronym class="acronym">BIND</
acronym> 8 have limited support
1736N/A TSIG can also be useful for dynamic update. A primary
1736N/A server for a dynamic zone should control access to the dynamic
1736N/A update service, but IP-based access control is insufficient.
1431N/A The cryptographic access control provided by TSIG
1431N/A is far superior. The <
span><
strong class="command">nsupdate</
strong></
span>
1431N/A program supports TSIG via the <
code class="option">-k</
code> and
1431N/A <
code class="option">-y</
code> command line options or inline by use
1431N/A of the <
span><
strong class="command">key</
strong></
span>.
1431N/A<
div class="sect2" lang="en">
1431N/A<
div class="titlepage"><
div><
div><
h3 class="title">
1431N/A<
a name="id2564004"></
a>Generate Shared Keys for Each Pair of Hosts</
h3></
div></
div></
div>
1431N/A A shared secret is generated to be shared between <
span class="emphasis"><
em>host1</
em></
span> and <
span class="emphasis"><
em>host2</
em></
span>.
1431N/A An arbitrary key name is chosen: "host1-host2.". The key name must
1431N/A<
div class="sect3" lang="en">
1431N/A<
div class="titlepage"><
div><
div><
h4 class="title">
1431N/A<
a name="id2564021"></
a>Automatic Generation</
h4></
div></
div></
div>
1431N/A The following command will generate a 128-bit (16 byte) HMAC-SHA256
1431N/A key as described above. Longer keys are better, but shorter keys
1431N/A are easier to read. Note that the maximum key length is the digest
1431N/A <
strong class="userinput"><
code>dnssec-keygen -a hmac-sha256 -b 128 -n HOST host1-host2.</
code></
strong>
1431N/A Nothing directly uses this file, but the base-64 encoded string
1431N/A following "<
code class="literal">Key:</
code>"
1431N/A can be extracted from the file and used as a shared secret:
1431N/A be used as the shared secret.
873N/A<
div class="sect3" lang="en">
873N/A<
div class="titlepage"><
div><
div><
h4 class="title">
873N/A<
a name="id2564059"></
a>Manual Generation</
h4></
div></
div></
div>
428N/A The shared secret is simply a random sequence of bits, encoded
873N/A in base-64. Most ASCII strings are valid base-64 strings (assuming
873N/A the length is a multiple of 4 and only valid characters are used),
1431N/A so the shared secret can be manually generated.
428N/A Also, a known string can be run through <
span><
strong class="command">mmencode</
strong></
span> or
873N/A a similar program to generate base-64 encoded data.
873N/A<
div class="sect2" lang="en">
873N/A<
div class="titlepage"><
div><
div><
h3 class="title">
873N/A<
a name="id2564077"></
a>Copying the Shared Secret to Both Machines</
h3></
div></
div></
div>
873N/A This is beyond the scope of DNS. A secure transport mechanism
873N/A should be used. This could be secure FTP, ssh, telephone, etc.
873N/A<
div class="sect2" lang="en">
873N/A<
div class="titlepage"><
div><
div><
h3 class="title">
1431N/A<
a name="id2564088"></
a>Informing the Servers of the Key's Existence</
h3></
div></
div></
div>
1431N/A Imagine <
span class="emphasis"><
em>host1</
em></
span> and <
span class="emphasis"><
em>host 2</
em></
span>
1431N/A both servers. The following is added to each server's <
code class="filename">
named.conf</
code> file:
1431N/A<
pre class="programlisting">
1431N/A The secret is the one generated above. Since this is a secret, it
1431N/A non-world readable, or the key directive be added to a non-world
1431N/A At this point, the key is recognized. This means that if the
1431N/A server receives a message signed by this key, it can verify the
1431N/A signature. If the signature is successfully verified, the
1431N/A response is signed by the same key.
1431N/A<
div class="sect2" lang="en">
1431N/A<
div class="titlepage"><
div><
div><
h3 class="title">
1542N/A<
a name="id2564124"></
a>Instructing the Server to Use the Key</
h3></
div></
div></
div>
1431N/A Since keys are shared between two hosts only, the server must
1431N/A be told when keys are to be used. The following is added to the <
code class="filename">
named.conf</
code> file
1463N/A for <
span class="emphasis"><
em>host1</
em></
span>, if the IP address of <
span class="emphasis"><
em>host2</
em></
span> is
1431N/A<
pre class="programlisting">
1431N/A Multiple keys may be present, but only the first is used.
1431N/A This directive does not contain any secrets, so it may be in a
1472N/A If <
span class="emphasis"><
em>host1</
em></
span> sends a message that is a request
1431N/A to that address, the message will be signed with the specified key. <
span class="emphasis"><
em>host1</
em></
span> will
1431N/A expect any responses to signed messages to be signed with the same
1431N/A A similar statement must be present in <
span class="emphasis"><
em>host2</
em></
span>'s
1431N/A configuration file (with <
span class="emphasis"><
em>host1</
em></
span>'s address) for <
span class="emphasis"><
em>host2</
em></
span> to
1431N/A sign request messages to <
span class="emphasis"><
em>host1</
em></
span>.
1431N/A<
div class="sect2" lang="en">
1431N/A<
div class="titlepage"><
div><
div><
h3 class="title">
1431N/A<
a name="id2572169"></
a>TSIG Key Based Access Control</
h3></
div></
div></
div>
1431N/A <
acronym class="acronym">BIND</
acronym> allows IP addresses and ranges
1431N/A <
span><
strong class="command">allow-{ query | transfer | update }</
strong></
span>
1431N/A This has been extended to allow TSIG keys also. The above key would
1431N/A be denoted <
span><
strong class="command">key host1-host2.</
strong></
span>
1542N/A An example of an <
span><
strong class="command">allow-update</
strong></
span> directive would be:
1542N/A<
pre class="programlisting">
1542N/Aallow-update { key host1-host2. ;};
1431N/A This allows dynamic updates to succeed only if the request
1431N/A was signed by a key named "<
span><
strong class="command">host1-host2.</
strong></
span>".
1431N/A See <
a href="Bv9ARM.ch06.html#dynamic_update_policies" title="Dynamic Update Policies">the section called “Dynamic Update Policies”</
a> for a discussion of
1463N/A the more flexible <
span><
strong class="command">update-policy</
strong></
span> statement.
1542N/A<
div class="sect2" lang="en">
1431N/A<
div class="titlepage"><
div><
div><
h3 class="title">
1431N/A<
a name="id2572218"></
a>Errors</
h3></
div></
div></
div>
1431N/A The processing of TSIG signed messages can result in
1431N/A several errors. If a signed message is sent to a non-TSIG aware
1431N/A server, a FORMERR (format error) will be returned, since the server will not
1431N/A understand the record. This is a result of misconfiguration,
1431N/A since the server must be explicitly configured to send a TSIG
1431N/A signed message to a specific server.
1542N/A If a TSIG aware server receives a message signed by an
1431N/A unknown key, the response will be unsigned with the TSIG
1431N/A extended error code set to BADKEY. If a TSIG aware server
1635N/A receives a message with a signature that does not validate, the
1635N/A response will be unsigned with the TSIG extended error code set
1431N/A to BADSIG. If a TSIG aware server receives a message with a time
1431N/A outside of the allowed range, the response will be signed with
1431N/A the TSIG extended error code set to BADTIME, and the time values
1431N/A will be adjusted so that the response can be successfully
1431N/A verified. In any of these cases, the message's rcode (response code) is set to
1431N/A NOTAUTH (not authenticated).
1431N/A<
div class="sect1" lang="en">
1431N/A<
div class="titlepage"><
div><
div><
h2 class="title" style="clear: both">
1431N/A<
a name="id2572232"></
a>TKEY</
h2></
div></
div></
div>
1431N/A<
p><
span><
strong class="command">TKEY</
strong></
span>
1431N/A is a mechanism for automatically generating a shared secret
1431N/A between two hosts. There are several "modes" of
1431N/A <
span><
strong class="command">TKEY</
strong></
span> that specify how the key is generated
1431N/A or assigned. <
acronym class="acronym">BIND</
acronym> 9 implements only one of
1431N/A these modes, the Diffie-Hellman key exchange. Both hosts are
1431N/A required to have a Diffie-Hellman KEY record (although this
1431N/A record is not required to be present in a zone). The
1431N/A <
span><
strong class="command">TKEY</
strong></
span> process must use signed messages,
1431N/A signed either by TSIG or SIG(0). The result of
1431N/A <
span><
strong class="command">TKEY</
strong></
span> is a shared secret that can be used to
1431N/A sign messages with TSIG. <
span><
strong class="command">TKEY</
strong></
span> can also be
1431N/A used to delete shared secrets that it had previously
1431N/A The <
span><
strong class="command">TKEY</
strong></
span> process is initiated by a
1542N/A or server by sending a signed <
span><
strong class="command">TKEY</
strong></
span>
1431N/A (including any appropriate KEYs) to a TKEY-aware server. The
1431N/A server response, if it indicates success, will contain a
1431N/A <
span><
strong class="command">TKEY</
strong></
span> record and any appropriate keys.
1431N/A this exchange, both participants have enough information to
1431N/A determine the shared secret; the exact process depends on the
1431N/A <
span><
strong class="command">TKEY</
strong></
span> mode. When using the
1431N/A <
span><
strong class="command">TKEY</
strong></
span> mode, Diffie-Hellman keys are
1475N/A and the shared secret is derived by both participants.
1431N/A<
div class="sect1" lang="en">
1431N/A<
div class="titlepage"><
div><
div><
h2 class="title" style="clear: both">
1431N/A<
a name="id2572281"></
a>SIG(0)</
h2></
div></
div></
div>
1542N/A <
acronym class="acronym">BIND</
acronym> 9 partially supports DNSSEC SIG(0)
1542N/A transaction signatures as specified in RFC 2535 and RFC 2931.
1542N/A is performed in the same manner as TSIG keys; privileges can be
1542N/A granted or denied based on the key name.
1542N/A When a SIG(0) signed message is received, it will only be
1431N/A verified if the key is known and trusted by the server; the server
1431N/A SIG(0) signing of multiple-message TCP streams is not
1431N/A The only tool shipped with <
acronym class="acronym">BIND</
acronym> 9 that
1431N/A generates SIG(0) signed messages is <
span><
strong class="command">nsupdate</
strong></
span>.
1431N/A<
div class="sect1" lang="en">
1431N/A<
div class="titlepage"><
div><
div><
h2 class="title" style="clear: both">
1431N/A<
a name="DNSSEC"></
a>DNSSEC</
h2></
div></
div></
div>
1431N/A Cryptographic authentication of DNS information is possible
1431N/A through the DNS Security (<
span class="emphasis"><
em>DNSSEC-bis</
em></
span>) extensions,
1431N/A defined in RFC 4033, RFC 4034, and RFC 4035.
1431N/A This section describes the creation and use of DNSSEC signed zones.
1431N/A In order to set up a DNSSEC secure zone, there are a series
1431N/A of steps which must be followed. <
acronym class="acronym">BIND</
acronym>
1431N/A that are used in this process, which are explained in more detail
1431N/A below. In all cases, the <
code class="option">-h</
code> option prints a
1431N/A full list of parameters. Note that the DNSSEC tools require the
1431N/A keyset files to be in the working directory or the
1431N/A directory specified by the <
code class="option">-d</
code> option, and
1431N/A that the tools shipped with BIND
9.2.x and earlier are not compatible
1431N/A There must also be communication with the administrators of
1431N/A the parent
and/
or child zone to transmit keys. A zone's security
1431N/A status must be indicated by the parent zone for a DNSSEC capable
1431N/A resolver to trust its data. This is done through the presence
1431N/A or absence of a <
code class="literal">DS</
code> record at the
1431N/A For other servers to trust data in this zone, they must
1431N/A either be statically configured with this zone's zone key or the
1431N/A zone key of another zone above this one in the DNS tree.
1431N/A<
div class="sect2" lang="en">
1431N/A<
div class="titlepage"><
div><
div><
h3 class="title">
1431N/A<
a name="id2572486"></
a>Generating Keys</
h3></
div></
div></
div>
1431N/A The <
span><
strong class="command">dnssec-keygen</
strong></
span> program is used to
1431N/A A secure zone must contain one or more zone keys. The
1431N/A zone keys will sign all other records in the zone, as well as
1431N/A the zone keys of any secure delegated zones. Zone keys must
1431N/A have the same name as the zone, a name type of
1431N/A <
span><
strong class="command">ZONE</
strong></
span>, and must be usable for
1431N/A It is recommended that zone keys use a cryptographic algorithm
1431N/A designated as "mandatory to implement" by the IETF; currently
1431N/A The following command will generate a 768-bit RSASHA1 key for
1431N/A <
strong class="userinput"><
code>dnssec-keygen -a RSASHA1 -b 768 -n ZONE
child.example.</
code></
strong>
1779N/A Two output files will be produced:
1779N/A 12345 is an example of a key tag). The key filenames contain
1779N/A is DSA, 1 is RSAMD5, 5 is RSASHA1, etc.), and the key tag (12345 in
1431N/A The private key (in the <
code class="filename">.private</
code>
1779N/A used to generate signatures, and the public key (in the
1507N/A <
code class="filename">.key</
code> file) is used for signature
1779N/A To generate another key with the same properties (but with
1779N/A a different key tag), repeat the above command.
1779N/A The <
span><
strong class="command">dnssec-keyfromlabel</
strong></
span> program is used
1779N/A to get a key pair from a crypto hardware and build the key
1779N/A files. Its usage is similar to <
span><
strong class="command">dnssec-keygen</
strong></
span>.
1779N/A The public keys should be inserted into the zone file by
1779N/A including the <
code class="filename">.key</
code> files using
1779N/A <
span><
strong class="command">$INCLUDE</
strong></
span> statements.
1431N/A<
div class="sect2" lang="en">
1779N/A<
div class="titlepage"><
div><
div><
h3 class="title">
1779N/A<
a name="id2572633"></
a>Signing the Zone</
h3></
div></
div></
div>
1431N/A The <
span><
strong class="command">dnssec-signzone</
strong></
span> program is used
1431N/A Any <
code class="filename">keyset</
code> files corresponding to
1431N/A secure subzones should be present. The zone signer will
1431N/A generate <
code class="literal">NSEC</
code>, <
code class="literal">NSEC3</
code>
1431N/A and <
code class="literal">RRSIG</
code> records for the zone, as
1431N/A well as <
code class="literal">DS</
code> for the child zones if
1431N/A <
code class="literal">'-g'</
code> is specified. If <
code class="literal">'-g'</
code>
1431N/A is not specified, then DS RRsets for the secure child
1431N/A zones need to be added manually.
1431N/A The following command signs the zone, assuming it is in a
1431N/A default, all zone keys which have an available private key are
1431N/A used to generate signatures.
1431N/A One output file is produced:
1431N/A<
p><
span><
strong class="command">dnssec-signzone</
strong></
span>
1431N/A will also produce a keyset and dsset files and optionally a
1431N/A dlvset file. These are used to provide the parent zone
1431N/A administrators with the <
code class="literal">DNSKEYs</
code> (or their
1431N/A corresponding <
code class="literal">DS</
code> records) that are the
1431N/A secure entry point to the zone.
1452N/A<
div class="sect2" lang="en">
1452N/A<
div class="titlepage"><
div><
div><
h3 class="title">
1431N/A<
a name="id2572782"></
a>Configuring Servers</
h3></
div></
div></
div>
1431N/A To enable <
span><
strong class="command">named</
strong></
span> to respond appropriately
1431N/A to DNS requests from DNSSEC aware clients,
1431N/A <
span><
strong class="command">dnssec-enable</
strong></
span> must be set to yes.
1431N/A (This is the default setting.)
1431N/A To enable <
span><
strong class="command">named</
strong></
span> to validate answers from
1431N/A other servers, the <
span><
strong class="command">dnssec-enable</
strong></
span> option
1431N/A must be set to <
strong class="userinput"><
code>yes</
code></
strong>, and the
1431N/A <
span><
strong class="command">dnssec-validation</
strong></
span> options must be set to
1431N/A <
strong class="userinput"><
code>yes</
code></
strong> or <
strong class="userinput"><
code>auto</
code></
strong>.
1431N/A If <
span><
strong class="command">dnssec-validation</
strong></
span> is set to
1431N/A <
strong class="userinput"><
code>auto</
code></
strong>, then a default
1431N/A trust anchor for the DNS root zone will be used.
1431N/A If it is set to <
strong class="userinput"><
code>yes</
code></
strong>, however,
1431N/A then at least one trust anchor must be configured
1431N/A with a <
span><
strong class="command">trusted-keys</
strong></
span> or
1431N/A <
span><
strong class="command">managed-keys</
strong></
span> statement in
1431N/A will not occur. The default setting is
1431N/A <
strong class="userinput"><
code>yes</
code></
strong>.
1431N/A <
span><
strong class="command">trusted-keys</
strong></
span> are copies of DNSKEY RRs
1431N/A for zones that are used to form the first link in the
1431N/A cryptographic chain of trust. All keys listed in
1431N/A <
span><
strong class="command">trusted-keys</
strong></
span> (and corresponding zones)
1475N/A are deemed to exist and only the listed keys will be used
1475N/A to validated the DNSKEY RRset that they are from.
1431N/A <
span><
strong class="command">managed-keys</
strong></
span> are trusted keys which are
1431N/A automatically kept up to date via RFC 5011 trust anchor
1431N/A <
span><
strong class="command">trusted-keys</
strong></
span> and
1431N/A <
span><
strong class="command">managed-keys</
strong></
span> are described in more detail
1431N/A Unlike <
acronym class="acronym">BIND</
acronym> 8, <
acronym class="acronym">BIND</
acronym>
1431N/A 9 does not verify signatures on load, so zone keys for
1431N/A authoritative zones do not need to be specified in the
451N/A After DNSSEC gets established, a typical DNSSEC configuration
873N/A will look something like the following. It has one or
1431N/A more public keys for the root. This allows answers from
873N/A outside the organization to be validated. It will also
433N/A have several keys for parts of the namespace the organization
873N/A controls. These are here to ensure that <
span><
strong class="command">named</
strong></
span>
797N/A is immune to compromises in the DNSSEC components of the security
1431N/A<
pre class="programlisting">
797N/A "." initial-key 257 3 3 "BNY4wrWM1nCfJ+CXd0rVXyYmobt7sEEfK3clRbGaTwS
382N/A 66gKodQj+MiA21AfUVe7u99WzTLzY3qlxDhxYQQ20FQ
1431N/A dgxbcDTClU0CRBdiieyLMNzXG3";
1431N/A /* Key for our organization's forward zone */
1431N/A 5KbhTjrW1ZaARmPhEZZe3Y9ifgEuq7vZ/z
1431N/A GZUdEGNWy+JZzus0lUptwgjGwhUS1558Hb
1431N/A 4JKUbbOTcM8pwXlj0EiX3oDFVmjHO444gL
1431N/A g4ywzO9WglMk7jbfW33gUKvirTHr25GL7S
1431N/A TQUzBb5Usxt8lgnyTUHs1t3JwCY5hKZ6Cq
1431N/A F4qJCyduieHukuY3H4XMAcR+xia2nIUPvm
1431N/A /* Key for our reverse zone. */
382N/A LhGTnNGp3HoWQLUIzKrJVZ3zg
873N/A gy3WwNT6kZo6c0tszYqbtvchm
873N/A siaOdS0yOI6BgPsw+YZdzlYMa
382N/A IJGf4M4dyoKIhzdZyQ2bYQrjy
1431N/A<
div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
1431N/A None of the keys listed in this example are valid. In particular,
1431N/A When DNSSEC validation is enabled and properly configured,
1431N/A the resolver will reject any answers from signed, secure zones
1431N/A which fail to validate, and will return SERVFAIL to the client.
1431N/A Responses may fail to validate for any of several reasons,
1431N/A including missing, expired, or invalid signatures, a key which
1431N/A does not match the DS RRset in the parent zone, or an insecure
1431N/A response from a zone which, according to its parent, should have
1431N/A<
div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
1431N/A When the validator receives a response from an unsigned zone
1431N/A that has a signed parent, it must confirm with the parent
1431N/A that the zone was intentionally left unsigned. It does
1431N/A that the parent zone contains no DS records for the child.
1431N/A If the validator <
span class="emphasis"><
em>can</
em></
span> prove that the zone
1431N/A is insecure, then the response is accepted. However, if it
1431N/A cannot, then it must assume an insecure response to be a
1431N/A forgery; it rejects the response and logs an error.
1431N/A The logged error reads "insecurity proof failed" and
1431N/A "got insecure response; parent indicates it should be secure".
1431N/A (Prior to BIND 9.7, the logged error was "not insecure".
1431N/A This referred to the zone, not the response.)
1431N/A<
div class="sect1" lang="en">
1431N/A<
div class="titlepage"><
div><
div><
h2 class="title" style="clear: both">
1431N/A<
p>As of BIND 9.7.0 it is possible to change a dynamic zone
1431N/A from insecure to signed and back again. A secure zone can use
1431N/A either NSEC or NSEC3 chains.</
p>
1431N/A<
div class="sect2" lang="en"><
div class="titlepage"><
div><
div><
h3 class="title">
1431N/A<
a name="id2609234"></
a>Converting from insecure to secure</
h3></
div></
div></
div></
div>
1431N/A<
p>Changing a zone from insecure to secure can be done in two
1431N/A ways: using a dynamic DNS update, or the
1431N/A <
span><
strong class="command">auto-dnssec</
strong></
span> zone option.</
p>
1431N/A<
p>For either method, you need to configure
1431N/A <
span><
strong class="command">named</
strong></
span> so that it can see the
1431N/A <
code class="filename">K*</
code> files which contain the public and private
1431N/A parts of the keys that will be used to sign the zone. These files
1431N/A will have been generated by
1431N/A <
span><
strong class="command">dnssec-keygen</
strong></
span>. You can do this by placing them
1431N/A in the key-directory, as specified in
1431N/A<
pre class="programlisting">
1431N/A<
p>If one KSK and one ZSK DNSKEY key have been generated, this
1431N/A configuration will cause all records in the zone to be signed
1431N/A with the ZSK, and the DNSKEY RRset to be signed with the KSK as
1431N/A well. An NSEC chain will be generated as part of the initial
873N/A<
div class="sect2" lang="en"><
div class="titlepage"><
div><
div><
h3 class="title">
1542N/A<
a name="id2609271"></
a>Dynamic DNS update method</
h3></
div></
div></
div></
div>
873N/A<
p>To insert the keys via dynamic update:</
p>
382N/A<
p>While the update request will complete almost immediately,
1431N/A the zone will not be completely signed until
873N/A <
span><
strong class="command">named</
strong></
span> has had time to walk the zone and
873N/A generate the NSEC and RRSIG records. The NSEC record at the apex
873N/A will be added last, to signal that there is a complete NSEC
1542N/A<
p>If you wish to sign using NSEC3 instead of NSEC, you should
1542N/A add an NSEC3PARAM record to the initial update request. If you
1431N/A wish the NSEC3 chain to have the OPTOUT bit set, set it in the
873N/A flags field of the NSEC3PARAM record.</
p>
382N/A<
p>Again, this update request will complete almost
873N/A immediately; however, the record won't show up until
873N/A <
span><
strong class="command">named</
strong></
span> has had a chance to
build/
remove the
382N/A relevant chain. A private type record will be created to record
1452N/A the state of the operation (see below for more details), and will
1452N/A be removed once the operation completes.</
p>
1452N/A is happening, other updates are possible as well.</
p>
1507N/A<
div class="sect2" lang="en"><
div class="titlepage"><
div><
div><
h3 class="title">
1431N/A<
a name="id2563569"></
a>Fully automatic zone signing</
h3></
div></
div></
div></
div>
1431N/A<
p>To enable automatic signing, add the
1431N/A <
span><
strong class="command">auto-dnssec</
strong></
span> option to the zone statement in
1431N/A <
span><
strong class="command">auto-dnssec</
strong></
span> has two possible arguments:
1431N/A <
code class="constant">allow</
code> or
1431N/A <
code class="constant">maintain</
code>.</
p>
1431N/A <
span><
strong class="command">auto-dnssec allow</
strong></
span>,
1431N/A <
span><
strong class="command">named</
strong></
span> can search the key directory for keys
1431N/A matching the zone, insert them into the zone, and use them to
1431N/A sign the zone. It will do so only when it receives an
1431N/A <
span><
strong class="command">rndc sign <zonename></
strong></
span>.</
p>
1431N/A <
span><
strong class="command">auto-dnssec maintain</
strong></
span> includes the above
1431N/A functionality, but will also automatically adjust the zone's
1431N/A DNSKEY records on schedule according to the keys' timing metadata.
1431N/A (See <
a href="man.dnssec-keygen.html" title="dnssec-keygen"><
span class="refentrytitle"><
span class="application">dnssec-keygen</
span></
span>(8)</
a> and
1431N/A <
a href="man.dnssec-settime.html" title="dnssec-settime"><
span class="refentrytitle"><
span class="application">dnssec-settime</
span></
span>(8)</
a> for more information.)
1431N/A <
span><
strong class="command">named</
strong></
span> will periodically search the key directory
873N/A for keys matching the zone, and if the keys' metadata indicates
873N/A that any change should be made the zone, such as adding, removing,
873N/A or revoking a key, then that action will be carried out. By default,
382N/A the key directory is checked for changes every 60 minutes; this period
1431N/A can be adjusted with the <
code class="option">dnssec-loadkeys-interval</
code>, up
1431N/A to a maximum of 24 hours. The <
span><
strong class="command">rndc loadkeys</
strong></
span> forces
1431N/A <
span><
strong class="command">named</
strong></
span> to check for key updates immediately.
382N/A If keys are present in the key directory the first time the zone
873N/A is loaded, the zone will be signed immediately, without waiting for an
1431N/A <
span><
strong class="command">rndc sign</
strong></
span> or <
span><
strong class="command">rndc loadkeys</
strong></
span>
873N/A command. (Those commands can still be used when there are unscheduled
1431N/A If you wish the zone to be signed using NSEC3 instead of NSEC,
382N/A submit an NSEC3PARAM record via dynamic update prior to the
873N/A scheduled publication and activation of the keys. If you wish the
873N/A NSEC3 chain to have the OPTOUT bit set, set it in the flags field
873N/A of the NSEC3PARAM record. The NSEC3PARAM record will not appear in
382N/A the zone immediately, but it will be stored for later reference. When
1431N/A the zone is signed and the NSEC3 chain is completed, the NSEC3PARAM
1431N/A record will appear in the zone.
1431N/A <
span><
strong class="command">auto-dnssec</
strong></
span> option requires the zone to be
1431N/A configured to allow dynamic updates, by adding an
382N/A <
span><
strong class="command">allow-update</
strong></
span> or
873N/A <
span><
strong class="command">update-policy</
strong></
span> statement to the zone
1431N/A configuration. If this has not been done, the configuration will
1431N/A<
div class="sect2" lang="en"><
div class="titlepage"><
div><
div><
h3 class="title">
1431N/A<
a name="id2563877"></
a>Private-type records</
h3></
div></
div></
div></
div>
1431N/A<
p>The state of the signing process is signaled by
1431N/A private-type records (with a default type value of 65534). When
1431N/A signing is complete, these records will have a nonzero value for
1431N/A the final octet (for those records which have a nonzero initial
873N/A<
p>The private type record format: If the first octet is
1431N/A non-zero then the record indicates that the zone needs to be
1431N/A signed with the key matching the record, or that all signatures
1431N/A that match the record should be removed.</
p>
1431N/A<
div class="literallayout"><
p><
br>
1431N/A��key�id�in�network�order�(octet�2�and�3)<
br>
1431N/A��removal�flag�(octet�4)<
br>
1431N/A��complete�flag�(octet�5)<
br>
1542N/A<
p>Only records flagged as "complete" can be removed via
1542N/A dynamic update. Attempts to remove other private type records
1542N/A will be silently ignored.</
p>
1542N/A<
p>If the first octet is zero (this is a reserved algorithm
1542N/A number that should never appear in a DNSKEY record) then the
1542N/A record indicates changes to the NSEC3 chains are in progress. The
1542N/A rest of the record contains an NSEC3PARAM record. The flag field
1542N/A tells what operation to perform based on the flag bits.</
p>
1542N/A<
div class="literallayout"><
p><
br>
1431N/A<
div class="sect2" lang="en"><
div class="titlepage"><
div><
div><
h3 class="title">
1431N/A<
a name="id2563914"></
a>DNSKEY rollovers</
h3></
div></
div></
div></
div>
1431N/A<
p>As with insecure-to-secure conversions, rolling DNSSEC
1431N/A keys can be done in two ways: using a dynamic DNS update, or the
1431N/A <
span><
strong class="command">auto-dnssec</
strong></
span> zone option.</
p>
1431N/A<
div class="sect2" lang="en"><
div class="titlepage"><
div><
div><
h3 class="title">
1431N/A<
a name="id2563927"></
a>Dynamic DNS update method</
h3></
div></
div></
div></
div>
1431N/A<
p> To perform key rollovers via dynamic update, you need to add
1431N/A the <
code class="filename">K*</
code> files for the new keys so that
1431N/A <
span><
strong class="command">named</
strong></
span> can find them. You can then add the new
1431N/A DNSKEY RRs via dynamic update.
1431N/A <
span><
strong class="command">named</
strong></
span> will then cause the zone to be signed
1431N/A with the new keys. When the signing is complete the private type
1431N/A records will be updated so that the last octet is non
1431N/A<
p>If this is for a KSK you need to inform the parent and any
1431N/A trust anchor repositories of the new KSK.</
p>
1431N/A<
p>You should then wait for the maximum TTL in the zone before
1431N/A removing the old DNSKEY. If it is a KSK that is being updated,
1431N/A you also need to wait for the DS RRset in the parent to be
1431N/A updated and its TTL to expire. This ensures that all clients will
1431N/A be able to verify at least one signature when you remove the old
1431N/A<
p>The old DNSKEY can be removed via UPDATE. Take care to
1431N/A <
span><
strong class="command">named</
strong></
span> will clean out any signatures generated
1431N/A by the old key after the update completes.</
p>
1431N/A<
div class="sect2" lang="en"><
div class="titlepage"><
div><
div><
h3 class="title">
382N/A<
a name="id2571811"></
a>Automatic key rollovers</
h3></
div></
div></
div></
div>
1431N/A<
p>When a new key reaches its activation date (as set by
1431N/A <
span><
strong class="command">dnssec-keygen</
strong></
span> or <
span><
strong class="command">dnssec-settime</
strong></
span>),
1431N/A if the <
span><
strong class="command">auto-dnssec</
strong></
span> zone option is set to
1431N/A <
code class="constant">maintain</
code>, <
span><
strong class="command">named</
strong></
span> will
1635N/A automatically carry out the key rollover. If the key's algorithm
1635N/A has not previously been used to sign the zone, then the zone will
1431N/A be fully signed as quickly as possible. However, if the new key
1431N/A is replacing an existing key of the same algorithm, then the
1431N/A zone will be re-signed incrementally, with signatures from the
1431N/A old key being replaced with signatures from the new key as their
1431N/A signature validity periods expire. By default, this rollover
1431N/A completes in 30 days, after which it will be safe to remove the
1431N/A old key from the DNSKEY RRset.</
p>
1475N/A<
div class="sect2" lang="en"><
div class="titlepage"><
div><
div><
h3 class="title">
1475N/A<
a name="id2571837"></
a>NSEC3PARAM rollovers via UPDATE</
h3></
div></
div></
div></
div>
1431N/A<
p>Add the new NSEC3PARAM record via dynamic update. When the
1100N/A new NSEC3 chain has been generated, the NSEC3PARAM flag field
1431N/A will be zero. At this point you can remove the old NSEC3PARAM
1431N/A record. The old chain will be removed after the update request
1431N/A<
div class="sect2" lang="en"><
div class="titlepage"><
div><
div><
h3 class="title">
1431N/A<
a name="id2571847"></
a>Converting from NSEC to NSEC3</
h3></
div></
div></
div></
div>
1431N/A<
p>To do this, you just need to add an NSEC3PARAM record. When
1431N/A the conversion is complete, the NSEC chain will have been removed
1431N/A and the NSEC3PARAM record will have a zero flag field. The NSEC3
1431N/A chain will be generated before the NSEC chain is
1431N/A<
div class="sect2" lang="en"><
div class="titlepage"><
div><
div><
h3 class="title">
1431N/A<
a name="id2571857"></
a>Converting from NSEC3 to NSEC</
h3></
div></
div></
div></
div>
1431N/A<
p>To do this, use <
span><
strong class="command">nsupdate</
strong></
span> to
1893N/A remove all NSEC3PARAM records with a zero flag
1431N/A field. The NSEC chain will be generated before the NSEC3 chain is
1431N/A<
div class="sect2" lang="en"><
div class="titlepage"><
div><
div><
h3 class="title">
1431N/A<
a name="id2571869"></
a>Converting from secure to insecure</
h3></
div></
div></
div></
div>
1431N/A<
p>To convert a signed zone to unsigned using dynamic DNS,
1507N/A delete all the DNSKEY records from the zone apex using
1431N/A <
span><
strong class="command">nsupdate</
strong></
span>. All signatures, NSEC or NSEC3 chains,
1431N/A and associated NSEC3PARAM records will be removed automatically.
1431N/A This will take place after the update request completes.</
p>
1431N/A <
span><
strong class="command">dnssec-secure-to-insecure</
strong></
span> option to be set to
1431N/A <
strong class="userinput"><
code>yes</
code></
strong> in
1431N/A<
p>In addition, if the <
span><
strong class="command">auto-dnssec maintain</
strong></
span>
1431N/A zone statement is used, it should be removed or changed to
1431N/A <
span><
strong class="command">allow</
strong></
span> instead (or it will re-sign).
1291N/A<
div class="sect2" lang="en"><
div class="titlepage"><
div><
div><
h3 class="title">
1431N/A<
a name="id2571975"></
a>Periodic re-signing</
h3></
div></
div></
div></
div>
1191N/A<
p>In any secure zone which supports dynamic updates, named
1431N/A will periodically re-sign RRsets which have not been re-signed as
1431N/A a result of some update action. The signature lifetimes will be
1431N/A adjusted so as to spread the re-sign load over time rather than
1431N/A<
div class="sect2" lang="en"><
div class="titlepage"><
div><
div><
h3 class="title">
1431N/A<
a name="id2571985"></
a>NSEC3 and OPTOUT</
h3></
div></
div></
div></
div>
1431N/A <
span><
strong class="command">named</
strong></
span> only supports creating new NSEC3 chains
1431N/A where all the NSEC3 records in the zone have the same OPTOUT
1431N/A <
span><
strong class="command">named</
strong></
span> supports UPDATES to zones where the NSEC3
1431N/A records in the chain have mixed OPTOUT state.
1431N/A <
span><
strong class="command">named</
strong></
span> does not support changing the OPTOUT
1431N/A state of an individual NSEC3 record, the entire chain needs to be
1431N/A changed if the OPTOUT state of an individual NSEC3 needs to be
1431N/A<
div class="sect1" lang="en">
1537N/A<
div class="titlepage"><
div><
div><
h2 class="title" style="clear: both">
1431N/A<
p>BIND 9.7.0 introduces support for RFC 5011, dynamic trust
1431N/A anchor management. Using this feature allows
1431N/A <
span><
strong class="command">named</
strong></
span> to keep track of changes to critical
1191N/A DNSSEC keys without any need for the operator to make changes to
1431N/A<
div class="sect2" lang="en">
1431N/A<
div class="titlepage"><
div><
div><
h3 class="title">
1431N/A<
a name="id2572018"></
a>Validating Resolver</
h3></
div></
div></
div>
1431N/A<
p>To configure a validating resolver to use RFC 5011 to
1191N/A maintain a trust anchor, configure the trust anchor using a
1431N/A <
span><
strong class="command">managed-keys</
strong></
span> statement. Information about
1191N/A and Usage">the section called “<
span><
strong class="command">managed-keys</
strong></
span> Statement Definition
and Usage”</
a>.</
p>
<
div class="sect2" lang="en">
<
div class="titlepage"><
div><
div><
h3 class="title">
<
a name="id2572040"></
a>Authoritative Server</
h3></
div></
div></
div>
<
p>To set up an authoritative zone for RFC 5011 trust anchor
maintenance, generate two (or more) key signing keys (KSKs) for
the zone. Sign the zone with one of them; this is the "active"
KSK. All KSK's which do not sign the zone are "stand-by"
<
p>Any validating resolver which is configured to use the
active KSK as an RFC 5011-managed trust anchor will take note
of the stand-by KSKs in the zone's DNSKEY RRset, and store them
for future reference. The resolver will recheck the zone
periodically, and after 30 days, if the new key is still there,
then the key will be accepted by the resolver as a valid trust
anchor for the zone. Any time after this 30-day acceptance
timer has completed, the active KSK can be revoked, and the
zone can be "rolled over" to the newly accepted key.</
p>
<
p>The easiest way to place a stand-by key in a zone is to
use the "smart signing" features of
<
span><
strong class="command">dnssec-keygen</
strong></
span> and
<
span><
strong class="command">dnssec-signzone</
strong></
span>. If a key with a publication
date in the past, but an activation date which is unset or in
<
span><
strong class="command">dnssec-signzone -S</
strong></
span>" will include the DNSKEY
record in the zone, but will not sign with it:</
p>
$ <
strong class="userinput"><
code>dnssec-keygen -K keys -f KSK -P now -A now+2y
example.net</
code></
strong>
$ <
strong class="userinput"><
code>dnssec-signzone -S -K keys
example.net</
code></
strong>
<
p>To revoke a key, the new command
<
span><
strong class="command">dnssec-revoke</
strong></
span> has been added. This adds the
REVOKED bit to the key flags and re-generates the
<
code class="filename">K*.key</
code> and
<
code class="filename">K*.private</
code> files.</
p>
<
p>After revoking the active key, the zone must be signed
with both the revoked KSK and the new active KSK. (Smart
signing takes care of this automatically.)</
p>
<
p>Once a key has been revoked and used to sign the DNSKEY
RRset in which it appears, that key will never again be
accepted as a valid trust anchor by the resolver. However,
validation can proceed using the new active key (which had been
accepted by the resolver when it was a stand-by key).</
p>
<
p>See RFC 5011 for more details on key rollover
<
p>When a key has been revoked, its key ID changes,
increasing by 128, and wrapping around at 65535. So, for
example, the key "<
code class="filename">
Kexample.com.+005+10000</
code>" becomes
<
p>If two keys have ID's exactly 128 apart, and one is
revoked, then the two key ID's will collide, causing several
problems. To prevent this,
<
span><
strong class="command">dnssec-keygen</
strong></
span> will not generate a new key if
another key is present which may collide. This checking will
only occur if the new keys are written to the same directory
which holds all other keys in use for that zone.</
p>
<
p>Older versions of BIND 9 did not have this precaution.
Exercise caution if using key revocation on keys that were
generated by previous releases, or if using keys stored in
multiple directories or on multiple machines.</
p>
<
p>It is expected that a future release of BIND 9 will
address this problem in a different way, by storing revoked
keys with their original unrevoked key ID's.</
p>
<
div class="sect1" lang="en">
<
div class="titlepage"><
div><
div><
h2 class="title" style="clear: both">
<
a name="pkcs11"></
a>PKCS #11 (Cryptoki) support</
h2></
div></
div></
div>
<
p>PKCS #11 (Public Key Cryptography Standard #11) defines a
platform- independent API for the control of hardware security
modules (HSMs) and other cryptographic support devices.</
p>
<
p>BIND 9 is known to work with two HSMs: The Sun SCA 6000
cryptographic acceleration board, tested under Solaris x86, and
the AEP Keyper network-attached key storage device, tested with
Debian Linux, Solaris x86 and Windows Server 2003.</
p>
<
div class="sect2" lang="en">
<
div class="titlepage"><
div><
div><
h3 class="title">
<
a name="id2611670"></
a>Prerequisites</
h3></
div></
div></
div>
<
p>See the HSM vendor documentation for information about
installing, initializing, testing and troubleshooting the
<
p>BIND 9 uses OpenSSL for cryptography, but stock OpenSSL
does not yet fully support PKCS #11. However, a PKCS #11 engine
for OpenSSL is available from the OpenSolaris project. It has
been modified by ISC to work with with BIND 9, and to provide
new features such as PIN management and key by
<
p>The patched OpenSSL depends on a "PKCS #11 provider".
This is a shared library object, providing a low-level PKCS #11
interface to the HSM hardware. It is dynamically loaded by
OpenSSL at runtime. The PKCS #11 provider comes from the HSM
vendor, and is specific to the HSM to be controlled.</
p>
<
p>There are two "flavors" of PKCS #11 support provided by
the patched OpenSSL, one of which must be chosen at
configuration time. The correct choice depends on the HSM
<
div class="itemizedlist"><
ul type="disc">
<
li><
p>Use 'crypto-accelerator' with HSMs that have hardware
cryptographic acceleration features, such as the SCA 6000
board. This causes OpenSSL to run all supported
cryptographic operations in the HSM.</
p></
li>
<
li><
p>Use 'sign-only' with HSMs that are designed to
function primarily as secure key storage devices, but lack
hardware acceleration. These devices are highly secure, but
are not necessarily any faster at cryptography than the
system CPU — often, they are slower. It is therefore
most efficient to use them only for those cryptographic
functions that require access to the secured private key,
such as zone signing, and to use the system CPU for all
other computationally-intensive operations. The AEP Keyper
is an example of such a device.</
p></
li>
<
p>The modified OpenSSL code is included in the BIND 9 release,
in the form of a context diff against the latest verions of
OpenSSL. OpenSSL 0.9.8 and 1.0.0 are both supported; there are
separate diffs for each version. In the examples to follow,
we use OpenSSL 0.9.8, but the same methods work with OpenSSL 1.0.0.
<
div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
<
h3 class="title">Note</
h3>
The latest OpenSSL versions at the time of the BIND release
ISC will provide an updated patch as new versions of OpenSSL
are released. The version number in the following examples
is expected to change.</
div>
Before building BIND 9 with PKCS #11 support, it will be
necessary to build OpenSSL with this patch in place and inform
it of the path to the HSM-specific PKCS #11 provider
<
p>Obtain OpenSSL 0.9.8s:</
p>
<
p>Extract the tarball:</
p>
<
p>Apply the patch from the BIND 9 release:</
p>
$ <
strong class="userinput"><
code>patch -p1 -d openssl-0.9.8s \
<
div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
<
h3 class="title">Note</
h3>(Note that the patch file may not be compatible with the
"patch" utility on all operating systems. You may need to
install GNU patch.)</
div>
<
p>When building OpenSSL, place it in a non-standard
location so that it does not interfere with OpenSSL libraries
elsewhere on the system. In the following examples, we choose
to install into "/
opt/
pkcs11/
usr". We will use this location
when we configure BIND 9.</
p>
<
div class="sect3" lang="en">
<
div class="titlepage"><
div><
div><
h4 class="title">
<
a name="id2609308"></
a>Building OpenSSL for the AEP Keyper on Linux</
h4></
div></
div></
div>
<
p>The AEP Keyper is a highly secure key storage device,
but does not provide hardware cryptographic acceleration. It
can carry out cryptographic operations, but it is probably
slower than your system's CPU. Therefore, we choose the
'sign-only' flavor when building OpenSSL.</
p>
<
p>The Keyper-specific PKCS #11 provider library is
delivered with the Keyper software. In this example, we place
<
p>This library is only available for Linux as a 32-bit
binary. If we are compiling on a 64-bit Linux system, it is
necessary to force a 32-bit build, by specifying -m32 in the
<
p>Finally, the Keyper library requires threads, so we
must specify -pthread.</
p>
$ <
strong class="userinput"><
code>cd openssl-0.9.8s</
code></
strong>
$ <
strong class="userinput"><
code>/
Configure linux-generic32 -m32 -pthread \
--pk11-flavor=sign-only \
<
p>After configuring, run "<
span><
strong class="command">make</
strong></
span>"
and "<
span><
strong class="command">make test</
strong></
span>". If "<
span><
strong class="command">make
test</
strong></
span>" fails with "pthread_atfork() not found", you forgot to
add the -pthread above.</
p>
<
div class="sect3" lang="en">
<
div class="titlepage"><
div><
div><
h4 class="title">
<
a name="id2609446"></
a>Building OpenSSL for the SCA 6000 on Solaris</
h4></
div></
div></
div>
<
p>The SCA-6000 PKCS #11 provider is installed as a system
library, libpkcs11. It is a true crypto accelerator, up to 4
times faster than any CPU, so the flavor shall be
'crypto-accelerator'.</
p>
<
p>In this example, we are building on Solaris x86 on an
$ <
strong class="userinput"><
code>cd openssl-0.9.8s</
code></
strong>
$ <
strong class="userinput"><
code>/
Configure solaris64-x86_64-cc \
--pk11-flavor=crypto-accelerator \
<
p>(For a 32-bit build, use "solaris-x86-cc" and
<
p>After configuring, run
<
span><
strong class="command">make</
strong></
span> and
<
span><
strong class="command">make test</
strong></
span>.</
p>
<
div class="sect3" lang="en">
<
div class="titlepage"><
div><
div><
h4 class="title">
<
a name="id2609700"></
a>Building OpenSSL for SoftHSM</
h4></
div></
div></
div>
<
p>SoftHSM is a software library provided by the OpenDNSSEC
interface to a virtual HSM, implemented in the form of encrypted
data on the local filesystem. It uses the Botan library for
encryption and SQLite3 for data storage. Though less secure
than a true HSM, it can provide more secure key storage than
traditional key files, and can allow you to experiment with
PKCS#11 when an HSM is not available.</
p>
<
p>The SoftHSM cryptographic store must be installed and
initialized before using it with OpenSSL, and the SOFTHSM_CONF
environment variable must always point to the SoftHSM configuration
$ <
strong class="userinput"><
code> cd softhsm-1.3.0 </
code></
strong>
$ <
strong class="userinput"><
code> configure --prefix=/
opt/
pkcs11/
usr </
code></
strong>
$ <
strong class="userinput"><
code> make </
code></
strong>
$ <
strong class="userinput"><
code> make install </
code></
strong>
$ <
strong class="userinput"><
code> echo "0:/
opt/
pkcs11/
softhsm.db" > $SOFTHSM_CONF </
code></
strong>
$ <
strong class="userinput"><
code> /
opt/
pkcs11/
usr/
bin/
softhsm --init-token 0 --slot 0 --label softhsm </
code></
strong>
<
p>SoftHSM can perform all cryptographic operations, but
since it only uses your system CPU, there is no need to use it
for anything but signing. Therefore, we choose the 'sign-only'
flavor when building OpenSSL.</
p>
$ <
strong class="userinput"><
code>cd openssl-0.9.8s</
code></
strong>
$ <
strong class="userinput"><
code>/
Configure linux-x86_64 -pthread \
--pk11-flavor=sign-only \
<
p>After configuring, run "<
span><
strong class="command">make</
strong></
span>"
and "<
span><
strong class="command">make test</
strong></
span>".</
p>
<
p>Once you have built OpenSSL, run
"<
span><
strong class="command">
apps/
openssl engine pkcs11</
strong></
span>" to confirm
that PKCS #11 support was compiled in correctly. The output
should be one of the following lines, depending on the flavor
(pkcs11) PKCS #11 engine support (sign only)
(pkcs11) PKCS #11 engine support (crypto accelerator)
"<
span><
strong class="command">
apps/
openssl engine pkcs11 -t</
strong></
span>". This will
attempt to initialize the PKCS #11 engine. If it is able to
do so successfully, it will report
“<
span class="quote"><
code class="literal">[ available ]</
code></
span>”.</
p>
<
p>If the output is correct, run
"<
span><
strong class="command">make install</
strong></
span>" which will install the
modified OpenSSL suite to
<
div class="sect2" lang="en">
<
div class="titlepage"><
div><
div><
h3 class="title">
<
a name="id2609851"></
a>Building BIND 9 with PKCS#11</
h3></
div></
div></
div>
<
p>When building BIND 9, the location of the custom-built
OpenSSL library must be specified via configure.</
p>
<
div class="sect3" lang="en">
<
div class="titlepage"><
div><
div><
h4 class="title">
<
a name="id2609860"></
a>Configuring BIND 9 for Linux with the AEP Keyper</
h4></
div></
div></
div>
<
p>To link with the PKCS #11 provider, threads must be
enabled in the BIND 9 build.</
p>
<
p>The PKCS #11 library for the AEP Keyper is currently
only available as a 32-bit binary. If we are building on a
64-bit host, we must force a 32-bit build by adding "-m32" to
the CC options on the "configure" command line.</
p>
$ <
strong class="userinput"><
code>cd /
bind9</
code></
strong>
$ <
strong class="userinput"><
code>/
configure CC="gcc -m32" --enable-threads \
<
div class="sect3" lang="en">
<
div class="titlepage"><
div><
div><
h4 class="title">
<
a name="id2609892"></
a>Configuring BIND 9 for Solaris with the SCA 6000</
h4></
div></
div></
div>
<
p>To link with the PKCS #11 provider, threads must be
enabled in the BIND 9 build.</
p>
$ <
strong class="userinput"><
code>cd /
bind9</
code></
strong>
$ <
strong class="userinput"><
code>/
configure CC="cc -xarch=amd64" --enable-threads \
<
p>(For a 32-bit build, omit CC="cc -xarch=amd64".)</
p>
<
p>If configure complains about OpenSSL not working, you
may have a
32/
64-bit architecture mismatch. Or, you may have
incorrectly specified the path to OpenSSL (it should be the
same as the --prefix argument to the OpenSSL
<
div class="sect3" lang="en">
<
div class="titlepage"><
div><
div><
h4 class="title">
<
a name="id2612044"></
a>Configuring BIND 9 for SoftHSM</
h4></
div></
div></
div>
$ <
strong class="userinput"><
code>cd /
bind9</
code></
strong>
$ <
strong class="userinput"><
code>/
configure --enable-threads \
<
p>After configuring, run
"<
span><
strong class="command">make</
strong></
span>",
"<
span><
strong class="command">make test</
strong></
span>" and
"<
span><
strong class="command">make install</
strong></
span>".</
p>
<
p>(Note: If "make test" fails in the "pkcs11" system test, you may
have forgotten to set the SOFTHSM_CONF environment variable.)</
p>
<
div class="sect2" lang="en">
<
div class="titlepage"><
div><
div><
h3 class="title">
<
a name="id2612161"></
a>PKCS #11 Tools</
h3></
div></
div></
div>
<
p>BIND 9 includes a minimal set of tools to operate the
<
span><
strong class="command">pkcs11-keygen</
strong></
span> to generate a new key pair
<
span><
strong class="command">pkcs11-list</
strong></
span> to list objects currently
<
span><
strong class="command">pkcs11-destroy</
strong></
span> to remove objects.</
p>
<
p>In
UNIX/
Linux builds, these tools are built only if BIND
9 is configured with the --with-pkcs11 option. (NOTE: If
--with-pkcs11 is set to "yes", rather than to the path of the
PKCS #11 provider, then the tools will be built but the
provider will be left undefined. Use the -m option or the
PKCS11_PROVIDER environment variable to specify the path to the
<
div class="sect2" lang="en">
<
div class="titlepage"><
div><
div><
h3 class="title">
<
a name="id2612192"></
a>Using the HSM</
h3></
div></
div></
div>
<
p>First, we must set up the runtime environment so the
OpenSSL and PKCS #11 libraries can be loaded:</
p>
$ <
strong class="userinput"><
code>export LD_LIBRARY_PATH=/
opt/
pkcs11/
usr/
lib:${LD_LIBRARY_PATH}</
code></
strong>
<
p>When operating an AEP Keyper, it is also necessary to
specify the location of the "machine" file, which stores
information about the Keyper for use by PKCS #11 provider
library. If the machine file is in
<
p>These environment variables must be set whenever running
any tool that uses the HSM, including
<
span><
strong class="command">pkcs11-keygen</
strong></
span>,
<
span><
strong class="command">pkcs11-list</
strong></
span>,
<
span><
strong class="command">pkcs11-destroy</
strong></
span>,
<
span><
strong class="command">dnssec-keyfromlabel</
strong></
span>,
<
span><
strong class="command">dnssec-signzone</
strong></
span>,
<
span><
strong class="command">dnssec-keygen</
strong></
span>(which will use the HSM for
random number generation), and
<
span><
strong class="command">named</
strong></
span>.</
p>
<
p>We can now create and use keys in the HSM. In this case,
we will create a 2048 bit key and give it the label
$ <
strong class="userinput"><
code>pkcs11-keygen -b 2048 -l sample-ksk</
code></
strong>
<
p>To confirm that the key exists:</
p>
$ <
strong class="userinput"><
code>pkcs11-list</
code></
strong>
object[0]: handle 2147483658 class 3 label[8] 'sample-ksk' id[0]
object[1]: handle 2147483657 class 2 label[8] 'sample-ksk' id[0]
<
p>Before using this key to sign a zone, we must create a
pair of BIND 9 key files. The "dnssec-keyfromlabel" utility
does this. In this case, we will be using the HSM key
"sample-ksk" as the key-signing key for "
example.net":</
p>
$ <
strong class="userinput"><
code>dnssec-keyfromlabel -l sample-ksk -f KSK
example.net</
code></
strong>
<
p>The resulting K*.key and K*.private files can now be used
to sign the zone. Unlike normal K* files, which contain both
public and private key data, these files will contain only the
public key data, plus an identifier for the private key which
remains stored within the HSM. The HSM handles signing with the
<
p>If you wish to generate a second key in the HSM for use
as a zone-signing key, follow the same procedure above, using a
different keylabel, a smaller key size, and omitting "-f KSK"
from the dnssec-keyfromlabel arguments:</
p>
$ <
strong class="userinput"><
code>pkcs11-keygen -b 1024 -l sample-zsk</
code></
strong>
$ <
strong class="userinput"><
code>dnssec-keyfromlabel -l sample-zsk
example.net</
code></
strong>
<
p>Alternatively, you may prefer to generate a conventional
on-disk key, using dnssec-keygen:</
p>
$ <
strong class="userinput"><
code>dnssec-keygen
example.net</
code></
strong>
<
p>This provides less security than an HSM key, but since
HSMs can be slow or cumbersome to use for security reasons, it
may be more efficient to reserve HSM keys for use in the less
frequent key-signing operation. The zone-signing key can be
rolled more frequently, if you wish, to compensate for a
reduction in key security.</
p>
<
p>Now you can sign the zone. (Note: If not using the -S
<
span><
strong class="command">dnssec-signzone</
strong></
span>, it will be necessary to add
<
code class="filename">K*.key</
code> files to the zone master file before
$ <
strong class="userinput"><
code>dnssec-signzone -S
example.net</
code></
strong>
Verifying the zone using the following algorithms:
Algorithm: NSEC3RSASHA1: ZSKs: 1, KSKs: 1 active, 0 revoked, 0 stand-by
<
div class="sect2" lang="en">
<
div class="titlepage"><
div><
div><
h3 class="title">
<
a name="id2636556"></
a>Specifying the engine on the command line</
h3></
div></
div></
div>
<
p>The OpenSSL engine can be specified in
<
span><
strong class="command">named</
strong></
span> and all of the BIND
<
span><
strong class="command">dnssec-*</
strong></
span> tools by using the "-E
<engine>" command line option. If BIND 9 is built with
the --with-pkcs11 option, this option defaults to "pkcs11".
Specifying the engine will generally not be necessary unless
for some reason you wish to use a different OpenSSL
<
p>If you wish to disable use of the "pkcs11" engine —
for troubleshooting purposes, or because the HSM is unavailable
— set the engine to the empty string. For example:</
p>
$ <
strong class="userinput"><
code>dnssec-signzone -E '' -S
example.net</
code></
strong>
<
span><
strong class="command">dnssec-signzone</
strong></
span> to run as if it were compiled
without the --with-pkcs11 option.</
p>
<
div class="sect2" lang="en">
<
div class="titlepage"><
div><
div><
h3 class="title">
<
a name="id2636670"></
a>Running named with automatic zone re-signing</
h3></
div></
div></
div>
<
span><
strong class="command">named</
strong></
span> to dynamically re-sign zones using HSM
keys,
and/
or to to sign new records inserted via nsupdate, then
named must have access to the HSM PIN. This can be accomplished
by placing the PIN into the
openssl.cnf file (in the above
<
p>The location of the
openssl.cnf file can be overridden by
setting the OPENSSL_CONF environment variable before running
<
pre class="programlisting">
openssl_conf = openssl_def
PIN = <
em class="replaceable"><
code><PLACE PIN HERE></
code></
em>
<
p>This will also allow the dnssec-* tools to access the HSM
without PIN entry. (The pkcs11-* tools access the HSM directly,
not via OpenSSL, so a PIN will still be required to use
<
div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;">
<
h3 class="title">Warning</
h3>
<
p>Placing the HSM's PIN in a text file in
this manner may reduce the security advantage of using an
HSM. Be sure this is what you want to do before configuring
<
div class="sect1" lang="en">
<
div class="titlepage"><
div><
div><
h2 class="title" style="clear: both">
<
a name="dlz-info"></
a>DLZ (Dynamically Loadable Zones)</
h2></
div></
div></
div>
DLZ (Dynamically Loadable Zones) is an extention to BIND 9 that allows
zone data to be retrieved directly from an external database. There is
no required format or schema. DLZ drivers exist for several different
database backends including PostgreSQL, MySQL, and LDAP and can be
Historically, DLZ drivers had to be statically linked with the named
binary and were turned on via a configure option at compile time (for
example, <
strong class="userinput"><
code>"configure --with-dlz-ldap"</
code></
strong>).
Currently, the drivers provided in the BIND 9 tarball in
In BIND 9.8 and higher, it is possible to link some DLZ modules
dynamically at runtime, via the DLZ "dlopen" driver, which acts as a
generic wrapper around a shared object implementing the DLZ API. The
"dlopen" driver is linked into named by default, so configure options
are no longer necessary when using these dynamically linkable drivers,
but are still needed for the older drivers in
When the DLZ module provides data to named, it does so in text format.
The response is converted to DNS wire format by named. This
conversion, and the lack of any internal caching, places significant
limits on the query performance of DLZ modules. Consequently, DLZ is
not recommended for use on high-volume servers. However, it can be
used in a hidden master configuration, with slaves retrieving zone
updates via AXFR. (Note, however, that DLZ has no built-in support for
DNS notify; slaves are not automatically informed of changes to the
<
div class="sect2" lang="en">
<
div class="titlepage"><
div><
div><
h3 class="title">
<
a name="id2572136"></
a>Configuring DLZ</
h3></
div></
div></
div>
A DLZ database is configured with a <
span><
strong class="command">dlz</
strong></
span>
statement in <
code class="filename">
named.conf</
code>:
database "dlopen
driver.so <
code class="option">args</
code>";
This specifies a DLZ module to search when answering queries; the
module is implemented in <
code class="filename">
driver.so</
code> and is
loaded at runtime by the dlopen DLZ driver. Multiple
<
span><
strong class="command">dlz</
strong></
span> statements can be specified; when
answering a query, all DLZ modules with <
code class="option">search</
code>
set to <
code class="literal">yes</
code> will be queried to find out if
they contain an answer for the query name; the best available
answer will be returned to the client.
The <
code class="option">search</
code> option in the above example can be
omitted, because <
code class="literal">yes</
code> is the default value.
If <
code class="option">search</
code> is set to <
code class="literal">no</
code>, then
this DLZ module is <
span class="emphasis"><
em>not</
em></
span> searched for the best
match when a query is received. Instead, zones in this DLZ must be
separately specified in a zone statement. This allows you to
configure a zone normally using standard zone option semantics,
but specify a different database back-end for storage of the
zone's data. For example, to implement NXDOMAIN redirection using
a DLZ module for back-end storage of redirection rules:
database "dlopen
driver.so <
code class="option">args</
code>";
<
div class="sect2" lang="en">
<
div class="titlepage"><
div><
div><
h3 class="title">
<
a name="id2609686"></
a>Sample DLZ Driver</
h3></
div></
div></
div>
For guidance in implementation of DLZ modules, the directory
loaded at runtime by the "dlopen" DLZ driver.
The example sets up a single zone, whose name is passed
to the module as an argument in the <
span><
strong class="command">dlz</
strong></
span>
In the above example, the module is configured to create a zone
"
example.nil", which can answer queries and AXFR requests, and
accept DDNS updates. At runtime, prior to any updates, the zone
contains an SOA, NS, and a single A record at the apex:
The sample driver is capable of retrieving information about the
querying client, and altering its response on the basis of this
information. To demonstrate this feature, the example driver
responds to queries for "source-addr.<
code class="option">zonename</
code>>/TXT"
with the source address of the query. Note, however, that this
record will *not* be included in AXFR or ANY responses. Normally,
this feature would be used to alter responses in some other fashion,
e.g., by providing different address records for a particular name
depending on the network from which the query arrived.
Documentation of the DLZ module API can be found in
contains the header file <
code class="filename">
dlz_minimal.h</
code>, which
defines the API and should be included by any dynamically-linkable
<
div class="sect1" lang="en">
<
div class="titlepage"><
div><
div><
h2 class="title" style="clear: both">
<
a name="id2573006"></
a>IPv6 Support in <
acronym class="acronym">BIND</
acronym> 9</
h2></
div></
div></
div>
<
acronym class="acronym">BIND</
acronym> 9 fully supports all currently
defined forms of IPv6 name to address and address to name
lookups. It will also use IPv6 addresses to make queries when
running on an IPv6 capable system.
For forward lookups, <
acronym class="acronym">BIND</
acronym> 9 supports
only AAAA records. RFC 3363 deprecated the use of A6 records,
and client-side support for A6 records was accordingly removed
from <
acronym class="acronym">BIND</
acronym> 9.
However, authoritative <
acronym class="acronym">BIND</
acronym> 9 name servers still
load zone files containing A6 records correctly, answer queries
for A6 records, and accept zone transfer for a zone containing A6
For IPv6 reverse lookups, <
acronym class="acronym">BIND</
acronym> 9 supports
the traditional "nibble" format used in the
<
span class="emphasis"><
em>
ip6.arpa</
em></
span> domain, as well as the older, deprecated
<
span class="emphasis"><
em>
ip6.int</
em></
span> domain.
Older versions of <
acronym class="acronym">BIND</
acronym> 9
supported the "binary label" (also known as "bitstring") format,
but support of binary labels has been completely removed per
Many applications in <
acronym class="acronym">BIND</
acronym> 9 do not understand
the binary label format at all any more, and will return an
In particular, an authoritative <
acronym class="acronym">BIND</
acronym> 9
name server will not load a zone file containing binary labels.
For an overview of the format and structure of IPv6 addresses,
see <
a href="Bv9ARM.ch09.html#ipv6addresses" title="IPv6 addresses (AAAA)">the section called “IPv6 addresses (AAAA)”</
a>.
<
div class="sect2" lang="en">
<
div class="titlepage"><
div><
div><
h3 class="title">
<
a name="id2573068"></
a>Address Lookups Using AAAA Records</
h3></
div></
div></
div>
The IPv6 AAAA record is a parallel to the IPv4 A record,
and, unlike the deprecated A6 record, specifies the entire
IPv6 address in a single record. For example,
<
pre class="programlisting">
host 3600 IN AAAA 2001:db8::1
Use of IPv4-in-IPv6 mapped addresses is not recommended.
If a host has an IPv4 address, use an A record, not
a AAAA, with <
code class="literal">::ffff:192.168.42.1</
code> as
<
div class="sect2" lang="en">
<
div class="titlepage"><
div><
div><
h3 class="title">
<
a name="id2573090"></
a>Address to Name Lookups Using Nibble Format</
h3></
div></
div></
div>
When looking up an address in nibble format, the address
components are simply reversed, just as in IPv4, and
<
code class="literal">
ip6.arpa.</
code> is appended to the
For example, the following would provide reverse name lookup for
<
code class="literal">2001:db8::1</
code>.
<
pre class="programlisting">
1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0 14400 IN PTR (
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