/contrib/bind9/doc/arm/dnssec.xml
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1<?xml version="1.0" encoding="utf-8"?> 2<!-- 3 - Copyright (C) 2010, 2012 Internet Systems Consortium, Inc. ("ISC") 4 - 5 - Permission to use, copy, modify, and/or distribute this software for any 6 - purpose with or without fee is hereby granted, provided that the above 7 - copyright notice and this permission notice appear in all copies. 8 - 9 - THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH 10 - REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY 11 - AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT, 12 - INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM 13 - LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE 14 - OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR 15 - PERFORMANCE OF THIS SOFTWARE. 16--> 17 18<!-- $Id$ --> 19 20<sect1 id="dnssec.dynamic.zones"> 21 <title>DNSSEC, Dynamic Zones, and Automatic Signing</title> 22 <para>As of BIND 9.7.0 it is possible to change a dynamic zone 23 from insecure to signed and back again. A secure zone can use 24 either NSEC or NSEC3 chains.</para> 25 <sect2> 26 <title>Converting from insecure to secure</title> 27 </sect2> 28 <para>Changing a zone from insecure to secure can be done in two 29 ways: using a dynamic DNS update, or the 30 <command>auto-dnssec</command> zone option.</para> 31 <para>For either method, you need to configure 32 <command>named</command> so that it can see the 33 <filename>K*</filename> files which contain the public and private 34 parts of the keys that will be used to sign the zone. These files 35 will have been generated by 36 <command>dnssec-keygen</command>. You can do this by placing them 37 in the key-directory, as specified in 38 <filename>named.conf</filename>:</para> 39 <programlisting> 40 zone example.net { 41 type master; 42 update-policy local; 43 file "dynamic/example.net/example.net"; 44 key-directory "dynamic/example.net"; 45 }; 46</programlisting> 47 <para>If one KSK and one ZSK DNSKEY key have been generated, this 48 configuration will cause all records in the zone to be signed 49 with the ZSK, and the DNSKEY RRset to be signed with the KSK as 50 well. An NSEC chain will be generated as part of the initial 51 signing process.</para> 52 <sect2> 53 <title>Dynamic DNS update method</title> 54 </sect2> 55 <para>To insert the keys via dynamic update:</para> 56 <screen> 57 % nsupdate 58 > ttl 3600 59 > update add example.net DNSKEY 256 3 7 AwEAAZn17pUF0KpbPA2c7Gz76Vb18v0teKT3EyAGfBfL8eQ8al35zz3Y I1m/SAQBxIqMfLtIwqWPdgthsu36azGQAX8= 60 > update add example.net DNSKEY 257 3 7 AwEAAd/7odU/64o2LGsifbLtQmtO8dFDtTAZXSX2+X3e/UNlq9IHq3Y0 XtC0Iuawl/qkaKVxXe2lo8Ct+dM6UehyCqk= 61 > send 62</screen> 63 <para>While the update request will complete almost immediately, 64 the zone will not be completely signed until 65 <command>named</command> has had time to walk the zone and 66 generate the NSEC and RRSIG records. The NSEC record at the apex 67 will be added last, to signal that there is a complete NSEC 68 chain.</para> 69 <para>If you wish to sign using NSEC3 instead of NSEC, you should 70 add an NSEC3PARAM record to the initial update request. If you 71 wish the NSEC3 chain to have the OPTOUT bit set, set it in the 72 flags field of the NSEC3PARAM record.</para> 73 <screen> 74 % nsupdate 75 > ttl 3600 76 > update add example.net DNSKEY 256 3 7 AwEAAZn17pUF0KpbPA2c7Gz76Vb18v0teKT3EyAGfBfL8eQ8al35zz3Y I1m/SAQBxIqMfLtIwqWPdgthsu36azGQAX8= 77 > update add example.net DNSKEY 257 3 7 AwEAAd/7odU/64o2LGsifbLtQmtO8dFDtTAZXSX2+X3e/UNlq9IHq3Y0 XtC0Iuawl/qkaKVxXe2lo8Ct+dM6UehyCqk= 78 > update add example.net NSEC3PARAM 1 1 100 1234567890 79 > send 80</screen> 81 <para>Again, this update request will complete almost 82 immediately; however, the record won't show up until 83 <command>named</command> has had a chance to build/remove the 84 relevant chain. A private type record will be created to record 85 the state of the operation (see below for more details), and will 86 be removed once the operation completes.</para> 87 <para>While the initial signing and NSEC/NSEC3 chain generation 88 is happening, other updates are possible as well.</para> 89 <sect2> 90 <title>Fully automatic zone signing</title> 91 </sect2> 92 <para>To enable automatic signing, add the 93 <command>auto-dnssec</command> option to the zone statement in 94 <filename>named.conf</filename>. 95 <command>auto-dnssec</command> has two possible arguments: 96 <constant>allow</constant> or 97 <constant>maintain</constant>.</para> 98 <para>With 99 <command>auto-dnssec allow</command>, 100 <command>named</command> can search the key directory for keys 101 matching the zone, insert them into the zone, and use them to 102 sign the zone. It will do so only when it receives an 103 <command>rndc sign <zonename></command> or 104 <command>rndc loadkeys <zonename></command> command.</para> 105 <para> 106 <!-- TODO: this is repeated in the ARM --> 107 <command>auto-dnssec maintain</command> includes the above 108 functionality, but will also automatically adjust the zone's 109 DNSKEY records on schedule according to the keys' timing metadata. 110 (See <xref linkend="man.dnssec-keygen"/> and 111 <xref linkend="man.dnssec-settime"/> for more information.) 112 If keys are present in the key directory the first time the zone 113 is loaded, it will be signed immediately, without waiting for an 114 <command>rndc sign</command> or <command>rndc loadkeys</command> 115 command. (Those commands can still be used when there are unscheduled 116 key changes, however.) 117 </para> 118 <para>Using the 119 <command>auto-dnssec</command> option requires the zone to be 120 configured to allow dynamic updates, by adding an 121 <command>allow-update</command> or 122 <command>update-policy</command> statement to the zone 123 configuration. If this has not been done, the configuration will 124 fail.</para> 125 <sect2> 126 <title>Private-type records</title> 127 </sect2> 128 <para>The state of the signing process is signaled by 129 private-type records (with a default type value of 65534). When 130 signing is complete, these records will have a nonzero value for 131 the final octet (for those records which have a nonzero initial 132 octet).</para> 133 <para>The private type record format: If the first octet is 134 non-zero then the record indicates that the zone needs to be 135 signed with the key matching the record, or that all signatures 136 that match the record should be removed.</para> 137 <para> 138 <literallayout> 139<!-- TODO: how to format this? --> 140 algorithm (octet 1) 141 key id in network order (octet 2 and 3) 142 removal flag (octet 4) 143 complete flag (octet 5) 144</literallayout> 145 </para> 146 <para>Only records flagged as "complete" can be removed via 147 dynamic update. Attempts to remove other private type records 148 will be silently ignored.</para> 149 <para>If the first octet is zero (this is a reserved algorithm 150 number that should never appear in a DNSKEY record) then the 151 record indicates changes to the NSEC3 chains are in progress. The 152 rest of the record contains an NSEC3PARAM record. The flag field 153 tells what operation to perform based on the flag bits.</para> 154 <para> 155 <literallayout> 156<!-- TODO: how to format this? --> 157 0x01 OPTOUT 158 0x80 CREATE 159 0x40 REMOVE 160 0x20 NONSEC 161</literallayout> 162 </para> 163 <sect2> 164 <title>DNSKEY rollovers</title> 165 </sect2> 166 <para>As with insecure-to-secure conversions, rolling DNSSEC 167 keys can be done in two ways: using a dynamic DNS update, or the 168 <command>auto-dnssec</command> zone option.</para> 169 <sect2> 170 <title>Dynamic DNS update method</title> 171 </sect2> 172 <para> To perform key rollovers via dynamic update, you need to add 173 the <filename>K*</filename> files for the new keys so that 174 <command>named</command> can find them. You can then add the new 175 DNSKEY RRs via dynamic update. 176 <command>named</command> will then cause the zone to be signed 177 with the new keys. When the signing is complete the private type 178 records will be updated so that the last octet is non 179 zero.</para> 180 <para>If this is for a KSK you need to inform the parent and any 181 trust anchor repositories of the new KSK.</para> 182 <para>You should then wait for the maximum TTL in the zone before 183 removing the old DNSKEY. If it is a KSK that is being updated, 184 you also need to wait for the DS RRset in the parent to be 185 updated and its TTL to expire. This ensures that all clients will 186 be able to verify at least one signature when you remove the old 187 DNSKEY.</para> 188 <para>The old DNSKEY can be removed via UPDATE. Take care to 189 specify the correct key. 190 <command>named</command> will clean out any signatures generated 191 by the old key after the update completes.</para> 192 <sect2> 193 <title>Automatic key rollovers</title> 194 </sect2> 195 <para>When a new key reaches its activation date (as set by 196 <command>dnssec-keygen</command> or <command>dnssec-settime</command>), 197 if the <command>auto-dnssec</command> zone option is set to 198 <constant>maintain</constant>, <command>named</command> will 199 automatically carry out the key rollover. If the key's algorithm 200 has not previously been used to sign the zone, then the zone will 201 be fully signed as quickly as possible. However, if the new key 202 is replacing an existing key of the same algorithm, then the 203 zone will be re-signed incrementally, with signatures from the 204 old key being replaced with signatures from the new key as their 205 signature validity periods expire. By default, this rollover 206 completes in 30 days, after which it will be safe to remove the 207 old key from the DNSKEY RRset.</para> 208 <sect2> 209 <title>NSEC3PARAM rollovers via UPDATE</title> 210 </sect2> 211 <para>Add the new NSEC3PARAM record via dynamic update. When the 212 new NSEC3 chain has been generated, the NSEC3PARAM flag field 213 will be zero. At this point you can remove the old NSEC3PARAM 214 record. The old chain will be removed after the update request 215 completes.</para> 216 <sect2> 217 <title>Converting from NSEC to NSEC3</title> 218 </sect2> 219 <para>To do this, you just need to add an NSEC3PARAM record. When 220 the conversion is complete, the NSEC chain will have been removed 221 and the NSEC3PARAM record will have a zero flag field. The NSEC3 222 chain will be generated before the NSEC chain is 223 destroyed.</para> 224 <sect2> 225 <title>Converting from NSEC3 to NSEC</title> 226 </sect2> 227 <para>To do this, use <command>nsupdate</command> to 228 remove all NSEC3PARAM records with a zero flag 229 field. The NSEC chain will be generated before the NSEC3 chain is 230 removed.</para> 231 <sect2> 232 <title>Converting from secure to insecure</title> 233 </sect2> 234 <para>To convert a signed zone to unsigned using dynamic DNS, 235 delete all the DNSKEY records from the zone apex using 236 <command>nsupdate</command>. All signatures, NSEC or NSEC3 chains, 237 and associated NSEC3PARAM records will be removed automatically. 238 This will take place after the update request completes.</para> 239 <para> This requires the 240 <command>dnssec-secure-to-insecure</command> option to be set to 241 <userinput>yes</userinput> in 242 <filename>named.conf</filename>.</para> 243 <para>In addition, if the <command>auto-dnssec maintain</command> 244 zone statement is used, it should be removed or changed to 245 <command>allow</command> instead (or it will re-sign). 246 </para> 247 <sect2> 248 <title>Periodic re-signing</title> 249 </sect2> 250 <para>In any secure zone which supports dynamic updates, named 251 will periodically re-sign RRsets which have not been re-signed as 252 a result of some update action. The signature lifetimes will be 253 adjusted so as to spread the re-sign load over time rather than 254 all at once.</para> 255 <sect2> 256 <title>NSEC3 and OPTOUT</title> 257 </sect2> 258 <para> 259 <command>named</command> only supports creating new NSEC3 chains 260 where all the NSEC3 records in the zone have the same OPTOUT 261 state. 262 <command>named</command> supports UPDATES to zones where the NSEC3 263 records in the chain have mixed OPTOUT state. 264 <command>named</command> does not support changing the OPTOUT 265 state of an individual NSEC3 record, the entire chain needs to be 266 changed if the OPTOUT state of an individual NSEC3 needs to be 267 changed.</para> 268</sect1>