FreeBSD Bugzilla – Attachment 115485 Details for
Bug 157245
[PATCH] [RFC] Add a section about DNSSEC to the DNS chapter in the handbook
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[patch]
network-servers.chapter.sgml.diff
network-servers.chapter.sgml.diff (text/plain), 19.06 KB, created by
Niclas Zeising
on 2011-05-23 00:25:55 UTC
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network-servers.chapter.sgml.diff
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Niclas Zeising
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2011-05-23 00:25:55 UTC
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obsolete
>Index: en_US.ISO8859-1/books/handbook/network-servers/chapter.sgml >=================================================================== >RCS file: /home/ncvs/doc/en_US.ISO8859-1/books/handbook/network-servers/chapter.sgml,v >retrieving revision 1.130 >diff -u -d -r1.130 chapter.sgml >--- en_US.ISO8859-1/books/handbook/network-servers/chapter.sgml 15 May 2011 20:41:30 -0000 1.130 >+++ en_US.ISO8859-1/books/handbook/network-servers/chapter.sgml 22 May 2011 22:49:58 -0000 >@@ -3872,6 +3872,292 @@ > </sect2> > > <sect2> >+ <title>DNSSEC</title> >+ <indexterm> >+ <primary>BIND</primary> >+ <secondary>DNS security extensions</secondary> >+ </indexterm> >+ >+ <para>Domain Name System Security Extensions, or <acronym>DNSSEC</acronym> >+ for short, is a suite of specifications to protect >+ <acronym>DNS</acronym> clients, i.e. Internet resolvers, from forged >+ <acronym>DNS</acronym> data, such as spoofed <acronym>DNS</acronym> >+ records. By using digital signatures, a resolver can verify the >+ integrity and authenticity of the record. Note that >+ <acronym>DNSSEC</acronym> only provides integrity, it does not >+ provide neither confidentiality nor protection against false >+ assumptions. This meanins that it cannot protect against people going >+ to <hostid role="domainname">example.net</hostid> instead of >+ <hostid role="domainname">example.com</hostid>. The only >+ thing <acronym>DNSSEC</acronym> does is authenticate that the data is >+ from the domain owner and that it has not been compromised in transit. >+ The security of <acronym>DNS</acronym> is believed to be an important >+ step in securing the Internet in general. For a more in-depth >+ details of how <acronym>DNSSEC</acronym> works, the relevant >+ <acronym>RFC</acronym>s are a good place to start. See the list in >+ <xref linkend="dns-read">. >+ >+ <para>The next two sections will demonstrate how to enable >+ <acronym>DNSSEC</acronym> for an authoritative <acronym>DNS</acronym> >+ server and a recursive (or caching) <acronym>DNS</acronym> server >+ running <acronym>BIND</acronym>9. While all versions of >+ <acronym>BIND</acronym>9 support <acronym>DNSSEC</acronym>, it is >+ necessary to have at least version 9.6.2 in order to be able to use the >+ signed root zone when validating <acronym>DNS</acronym> queries. This is >+ because earlier versions lack the required algorithms to enable >+ validation using the root zone key. It is strongly recommended to use >+ <acronym>BIND</acronym> 9.7 or later to take advantage of automatic >+ key updating for the root key, as well as other features to >+ automatically keep zones signed and signatures up to date. Where >+ configurations differ between 9.6.2 and 9.7 and later, differences >+ will be pointed out.</para> >+ >+ <sect3> >+ <title>Recursive <acronym>DNS</acronym> server configuration</title> >+ >+ <para>Enabling <acronym>DNSSEC</acronym> validation of queries done by >+ a recursive <acronym>DNS</acronym> server reqires a few changes to >+ <filename>named.conf</filename>. Before making these changes >+ the root zone key, or trust anchor, must be aquired. Currently the >+ root zone key is not available in a file format >+ <acronym>BIND</acronym> understands, so it has to be manually >+ converted into the proper format. The key itself can be obtained by >+ querying the root zone for it, using <application>dig</application>. >+ By running >+ <screen>&prompt.user; <userinput>dig +multi +noall +answer DNSKEY . > root.dnskey</userinput></screen> >+ the key will end up in <filename>root.dnskey</filename>. The >+ contents should look something like this:<programlisting> >+. 93910 IN DNSKEY 257 3 8 ( >+ AwEAAagAIKlVZrpC6Ia7gEzahOR+9W29euxhJhVVLOyQ >+ bSEW0O8gcCjFFVQUTf6v58fLjwBd0YI0EzrAcQqBGCzh >+ /RStIoO8g0NfnfL2MTJRkxoXbfDaUeVPQuYEhg37NZWA >+ JQ9VnMVDxP/VHL496M/QZxkjf5/Efucp2gaDX6RS6CXp >+ oY68LsvPVjR0ZSwzz1apAzvN9dlzEheX7ICJBBtuA6G3 >+ LQpzW5hOA2hzCTMjJPJ8LbqF6dsV6DoBQzgul0sGIcGO >+ Yl7OyQdXfZ57relSQageu+ipAdTTJ25AsRTAoub8ONGc >+ LmqrAmRLKBP1dfwhYB4N7knNnulqQxA+Uk1ihz0= >+ ) ; key id = 19036 >+. 93910 IN DNSKEY 256 3 8 ( >+ AwEAAcaGQEA+OJmOzfzVfoYN249JId7gx+OZMbxy69Hf >+ UyuGBbRN0+HuTOpBxxBCkNOL+EJB9qJxt+0FEY6ZUVjE >+ g58sRr4ZQ6Iu6b1xTBKgc193zUARk4mmQ/PPGxn7Cn5V >+ EGJ/1h6dNaiXuRHwR+7oWh7DnzkIJChcTqlFrXDW3tjt >+ ) ; key id = 34525 >+ </programlisting>Do not be alarmed if the obtained keys differ from >+ this example, they might have changed since these instructions were >+ last updated. This output actually contains two keys. The first >+ key in the listing, with the value 257 behind the DNSKEY record >+ type, is the one needed. This value indicates that this is a >+ Secure Entry Point >+ (<acronym role="Secure Entry Point">SEP</acronym>), >+ more commonly known as a Key Signing Key >+ (<acronym role="Key Signing Key">KSK</acronym>). The second key, >+ with value 256, is a subordinate key, commonly called a Zone Signing >+ Key (<acronym role="Zone Signing Key">ZSK</acronym>). More on the >+ different key types later in the <xref linkend="dns-dnssec-auth">. >+ </para> >+ >+ <para>Now the key must be verified verified and formatted so that >+ <acronym>BIND</acronym> can use it. To verify the key, generate a >+ <acronym role="Delegation signer">DS</acronym> >+ <acronym role="Resource Record">RR</acronym> set. Create a file >+ containing these <acronym role="Resource Record">RR</acronym>s with >+ <screen>&prompt.user; <userinput>dnssec-dsfromkey -f root-dnskey . > root.ds</userinput></screen> >+ These records use SHA-1 and SHA-256 respectively, and should look >+ similar to the following example, where the longer is using SHA-256. >+ <programlisting> >+. IN DS 19036 8 1 B256BD09DC8DD59F0E0F0D8541B8328DD986DF6E >+. IN DS 19036 8 2 49AAC11D7B6F6446702E54A1607371607A1A41855200FD2CE1CDDE32F24E8FB5 >+ </programlisting>The SHA-256 <acronym>RR</acronym> can now be >+ compared to the digest in <ulink >+ url="https://data.iana.org/root-anchors/root-anchors.xml"> >+ https://data.iana.org/root-anchors/root-anchors.xml</ulink>. To be >+ absolutely sure that the key has not been tampered with, the data in >+ the <acronym>XML</acronym> file can be verified using the >+ <acronym>PGP</acronym> signature in <ulink >+ url="https://data.iana.org/root-anchors/root-anchors.asc"> >+ https://data.iana.org/root-anchors/root-anchors.asc</ulink>.</para> >+ >+ <para>Next, the key must be formatted properly. This differs a >+ little between <acronym>BIND</acronym> versions 9.6.2 and 9.7 and >+ later. Both use a <literal>managed-keys</literal> clause, but >+ support for <literal>initial-key</literal> was added in 9.7. >+ <literal>initial-key</literal> makes <acronym>BIND</acronym> >+ automatically track changes to the key and update it as necesarry. >+ Users of <acronym>BIND</acronym> 9.6.2 must do this manually. >+ For <acronym>BIND</acronym> 9.6.2 the format should look like: >+ <programlisting> >+managed-keys { >+ "." 257 3 8 >+ "AwEAAagAIKlVZrpC6Ia7gEzahOR+9W29euxhJhVVLOyQbSEW0O8gcCjF >+ FVQUTf6v58fLjwBd0YI0EzrAcQqBGCzh/RStIoO8g0NfnfL2MTJRkxoX >+ bfDaUeVPQuYEhg37NZWAJQ9VnMVDxP/VHL496M/QZxkjf5/Efucp2gaD >+ X6RS6CXpoY68LsvPVjR0ZSwzz1apAzvN9dlzEheX7ICJBBtuA6G3LQpz >+ W5hOA2hzCTMjJPJ8LbqF6dsV6DoBQzgul0sGIcGOYl7OyQdXfZ57relS >+ Qageu+ipAdTTJ25AsRTAoub8ONGcLmqrAmRLKBP1dfwhYB4N7knNnulq >+ QxA+Uk1ihz0="; >+}; >+ </programlisting>For 9.7 the format will instead be: >+ <programlisting> >+managed-keys { >+ "." initial-key 257 3 8 >+ "AwEAAagAIKlVZrpC6Ia7gEzahOR+9W29euxhJhVVLOyQbSEW0O8gcCjF >+ FVQUTf6v58fLjwBd0YI0EzrAcQqBGCzh/RStIoO8g0NfnfL2MTJRkxoX >+ bfDaUeVPQuYEhg37NZWAJQ9VnMVDxP/VHL496M/QZxkjf5/Efucp2gaD >+ X6RS6CXpoY68LsvPVjR0ZSwzz1apAzvN9dlzEheX7ICJBBtuA6G3LQpz >+ W5hOA2hzCTMjJPJ8LbqF6dsV6DoBQzgul0sGIcGOYl7OyQdXfZ57relS >+ Qageu+ipAdTTJ25AsRTAoub8ONGcLmqrAmRLKBP1dfwhYB4N7knNnulq >+ QxA+Uk1ihz0="; >+}; >+ </programlisting>The <literal>managed-keys</literal> directive can >+ now be added to <filename>named.conf</filename> either directly or >+ by including a file containing the key. After these steps, tell >+ <acronym>BIND</acronym> to do <acronym>DNSSEC</acronym> validation >+ on queries by editing <filename>named.conf</filename> and adding the >+ following to the <literal>options</literal> directive: >+ <programlisting> >+dnssec-enable yes; >+dnssec-validation yes; >+ </programlisting></para> >+ >+ <para>To verify that it is actually working, use >+ <application>dig</application> to make a query for a signed zone >+ using the resolver just configured. A successful reply will contain >+ the <literal>AD</literal> flag to indicate the data was >+ authenticated. Running a query such as >+ <screen>&prompt.user; <userinput>dig @<replaceable>resolver</replaceable> +dnssec se ds </userinput></screen> >+ should return the <acronym>DS</acronym> <acronym>RR</acronym> for >+ the .se zone. In the <literal>flags:</literal> section the >+ <literal>AD</literal> flag should be set, as seen >+ in:<programlisting> >+... >+;; flags: qr rd ra ad; QUERY: 1, ANSWER: 3, AUTHORITY: 0, ADDITIONAL: 1 >+... >+ </programlisting> This means that the resolver is now capable of >+ authenticating <acronym>DNS</acronym> queries.</para> >+ </sect3> >+ >+ <sect3 id="dns-dnssec-auth"> >+ <title>Authoritative <acronym>DNS</acronym> server configuration</title> >+ <para>In order to get an authoritative nameserver to serve a >+ <acronym>DNSSEC</acronym> signed zone, a little more work is >+ required. To sign a zone, two cryptographic keys for that zone must >+ be generated. These two keys are usually called the Key Signing Key >+ (<acronym role="Key Signing Key">KSK</acronym>) and Zone Signing Key >+ (<acronym role="Zone Signing Key">ZSK</acronym>) respectively. The >+ <acronym role="Key Signing Key">KSK</acronym> is used to build a chain >+ of authority to the data in need of validation and as such is also >+ called a Secure Entry Point >+ (<acronym role="Secure Entry Point">SEP</acronym>) key. This key >+ needs to be published in the parent zone as well, to establish the >+ trust chain. How this is accomplished depends on the parent zone >+ owner. The <acronym role="Zone Signing Key">ZSK</acronym> is used >+ to sign the zone, and only needs to be published there.</para> >+ >+ <para>To enable <acronym>DNSSEC</acronym> for the <hostid >+ role="domainname">example.com</hostid> zone depicted in previous >+ examples, the first step is to use >+ <application>dnssec-keygen</application> to generate the >+ <acronym>KSK</acronym> and <acronym>ZSK</acronym> keypair. This keypair >+ can utilize different cryptograhic algorithms. Currently the mandatory >+ algorithm is <literal>RSA/SHA-1</literal>. In the examples the key >+ length used is 2048 bits for the <acronym>KSK</acronym> and 1024 bits >+ for the <acronym>ZSK</acronym>. To generate the >+ <acronym>KSK</acronym> for <hostid >+ role="domainname">example.com</hostid>, run >+ <screen>&prompt.user; <userinput>dnssec-keygen -f KSK -a RSASHA1 -b 2048 -n ZONE example.com</userinput></screen> >+ and to generate the >+ <acronym>ZSK</acronym>, run >+ <screen>&prompt.user; <userinput>dnssec-keygen -a RSASHA1 -b 1024 -n ZONE example.com</userinput></screen> >+ <application>dnssec-keygen</application> outputs two files, the public >+ and the private keys in files named similar to >+ <filename>Kexample.com.+005+nnnnn.key</filename> (public) and >+ <filename>Kexample.com.+005+nnnnn.private</filename> (private). The >+ <literal>nnnnn</literal> part of the file name is a five digit key ID. >+ Keep track of which key ID belongs to which key. This is especially >+ important when having more than one key in a zone. The public key >+ files can now be included in the zone file, using the >+ <literal>$include</literal> statement. It should look something like >+ this:<programlisting> >+$include Kexample.net.+005+nnnnn.key ; ZSK >+$include Kexample.net.+005+nnnnn.key ; KSK >+ </programlisting></para> >+ >+ <para>Finally, sign the zone and tell <acronym>BIND</acronym> to use >+ the signed zonefile. To sign a zone >+ <application>dnssec-signzone</application> is used. The command to >+ sign the zone <hostid role="domainname">example.com</hostid>, located in >+ <filename>example.com.db</filename> would look similar to >+ <screen>&prompt.user; <userinput>dnssec-signzone -o example.com -k Kexample.com+005+nnnnn example.com.db Kexample.com+005+nnnnn.key</userinput></screen> >+ The key supplied to >+ the <option>-k</option> argument is the <acronym>KSK</acronym> and >+ the other key file is the <acronym>ZSK</acronym> that should be used >+ in the signing. It is possible to supply more than one >+ <acronym>KSK</acronym> and <acronym>ZSK</acronym>, which will result >+ in the zone being signed with all supplied keys. This can be needed >+ to supply zone data signed using more than one algorithm. The output >+ of <application>dnssec-signzone</application> is a zone file with all >+ <acronym>RR</acronym>s signed. This output will end up in a file with >+ the extension <literal>.signed</literal>, such as >+ <filename>example.com.db.signed</filename>. To use this signed zone >+ just modify the zone directive in <filename>named.conf</filename> to >+ use this file. By default, the signatures are only valid 30 days, >+ meaning that the zone needs to be resigned within this time. It is >+ possible to make a script and a cron job to do this. See relevant >+ manuals for details.</para> >+ >+ <para>Some cautionary words at the end. Be sure to keep private keys >+ confidential, as with all cryptographic keys. When changing a key it >+ is best to include the new key into the zone, while still signing with >+ the old key, and then move over to using the new key to sign. After >+ these steps are done the old key can be removed from the zone. >+ Failiure to do this might render the <acronym>DNS</acronym> data >+ unavailable for a time, until the new key has propagated through the >+ <acronym>DNS</acronym> hierarchy. For more information on key >+ rollovers and other <acronym>DNSSEC</acronym> operational issues, see >+ <ulink >+ url="http://www.ietf.org/rfc/rfc4641.txt"><acronym>RFC</acronym> 4641: >+ <acronym>DNSSEC</acronym> Operational practices</ulink>.</para> >+ </sect3> >+ >+ <sect3> >+ <title>Automation using <acronym>BIND</acronym> 9.7 or later</title> >+ <para>Beginning with <acronym>BIND</acronym> version 9.7, a new feature >+ called <emphasis>Smart Signing</emphasis> was introduced. This >+ feature aims to make the key management and signing process simpler by >+ automating parts of the task. By putting the keys into a directory >+ called a <emphasis>key repository</emphasis>, and using the new option >+ <literal>auto-dnssec</literal>, it is possible to create a dynamic zone >+ which will be resigned as needed. To update this zone use >+ <application>nsupdate</application> with the new option >+ <option>-l</option>. <application>rndc</application> has >+ also grown the ability to sign zones with keys in the key repository, >+ using the option <option>sign</option>. To tell >+ <acronym>BIND</acronym> to use this automatic signing and zone >+ updating for <hostid role="domainname">exanple.com</hostid>, add the >+ following to <filename>named.conf</filename>:<programlisting> >+zone example.com { >+ type master; >+ key-directory "keys"; >+ update-policy local; >+ auto-dnssec maintain; >+ file "dynamic/example.com.zone"; >+}; >+ </programlisting> After making these changes, generate keys for the >+ zone as explained in <xref linkend="dns-dnssec-auth">, put those keys >+ in the key repository given as the argument to the >+ <literal>key-directory</literal> in the zone configuration and sign >+ the zone using <application>rndc</application>. Updates to a zone >+ configured this way must be done using >+ <application>nsupdate</application>, which will take care of >+ re-signing the zone with the new data added. For further details, >+ see <xref linkend="dns-read"> and the <acronym>BIND</acronym> >+ documentation.</para> >+ </sect3> >+ >+ </sect2> >+ >+ <sect2> > <title>Security</title> > > <para>Although BIND is the most common implementation of DNS, >@@ -3897,11 +4183,12 @@ > </tip> > </sect2> > >- <sect2> >+ <sect2 id="dns-read"> > <title>Further Reading</title> > > <para>BIND/<application>named</application> manual pages: >- &man.rndc.8; &man.named.8; &man.named.conf.5;</para> >+ &man.rndc.8; &man.named.8; &man.named.conf.5; &man.nsupdate.8; >+ &man.dnssec-signzone.8; &man.dnssec-keygen.8;</para> > > <itemizedlist> > <listitem> >@@ -3932,6 +4219,38 @@ > url="http://tools.ietf.org/html/rfc1035">RFC1035 > - Domain Names - Implementation and Specification</ulink></para> > </listitem> >+ >+ <listitem> >+ <para><ulink >+ url="http://tools.ietf.org/html/rfc4033">RFC4033 >+ - DNS Security Introduction and Requirements</ulink></para> >+ </listitem> >+ >+ <listitem> >+ <para><ulink >+ url="http://tools.ietf.org/html/rfc4034">RFC4034 >+ - Recource Records for the DNS Security Extensions</ulink></para> >+ </listitem> >+ >+ <listitem> >+ <para><ulink >+ url="http://tools.ietf.org/html/rfc4035">RFC4035 >+ - Protocol Modifications for the DNS Security Extensions</ulink></para> >+ </listitem> >+ >+ <listitem> >+ <para><ulink >+ url="http://tools.ietf.org/html/rfc4641">RFC4641 >+ - DNSSEC Operational Practices</ulink></para> >+ </listitem> >+ >+ <listitem> >+ <para><ulink >+ url="http://tools.ietf.org/html/rfc5011">RFC 5011 >+ - Automated Updates of DNS Security (<acronym>DNSSEC</acronym> >+ Trust Anchors</ulink></para> >+ </listitem> >+ > </itemizedlist> > </sect2> > </sect1> >Index: share/sgml/man-refs.ent >=================================================================== >RCS file: /home/ncvs/doc/share/sgml/man-refs.ent,v >retrieving revision 1.511 >diff -u -d -r1.511 man-refs.ent >--- share/sgml/man-refs.ent 11 Feb 2011 16:15:44 -0000 1.511 >+++ share/sgml/man-refs.ent 22 May 2011 22:50:40 -0000 >@@ -4257,6 +4257,8 @@ > <!ENTITY man.diskpart.8 "<citerefentry/<refentrytitle/diskpart/<manvolnum/8//"> > <!ENTITY man.dm.8 "<citerefentry/<refentrytitle/dm/<manvolnum/8//"> > <!ENTITY man.dmesg.8 "<citerefentry/<refentrytitle/dmesg/<manvolnum/8//"> >+<!ENTITY man.dnssec-keygen.8 "<citerefentry/<refentrytitle/dnssec-keygen<manvolnum/8//"> >+<!ENTITY man.dnssec-signzone.8 "<citerefentry/<refentrytitle/dnssec-signzone<manvolnum/8//"> > <!ENTITY man.dump.8 "<citerefentry/<refentrytitle/dump/<manvolnum/8//"> > <!ENTITY man.dumpfs.8 "<citerefentry/<refentrytitle/dumpfs/<manvolnum/8//"> > <!ENTITY man.dumpon.8 "<citerefentry/<refentrytitle/dumpon/<manvolnum/8//">
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