1<?xml version="1.0" encoding="utf-8"?> 2<!-- 3 - Copyright (C) 2010 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: managed-keys.xml,v 1.3 2010/02/03 23:49:07 tbox Exp --> 19 20<sect1 id="rfc5011.support"> 21 <title>Dynamic Trust Anchor Management</title> 22 <para>BIND 9.7.0 introduces support for RFC 5011, dynamic trust 23 anchor management. Using this feature allows 24 <command>named</command> to keep track of changes to critical 25 DNSSEC keys without any need for the operator to make changes to 26 configuration files.</para> 27 <sect2> 28 <title>Validating Resolver</title> 29 <!-- TODO: command tag is overloaded for configuration and executables --> 30 <para>To configure a validating resolver to use RFC 5011 to 31 maintain a trust anchor, configure the trust anchor using a 32 <command>managed-keys</command> statement. Information about 33 this can be found in 34 <xref linkend="managed-keys" />.</para> 35 <!-- TODO: managed-keys examples 36also in DNSSEC section above here in ARM --> 37 </sect2> 38 <sect2> 39 <title>Authoritative Server</title> 40 <para>To set up an authoritative zone for RFC 5011 trust anchor 41 maintenance, generate two (or more) key signing keys (KSKs) for 42 the zone. Sign the zone with one of them; this is the "active" 43 KSK. All KSK's which do not sign the zone are "stand-by" 44 keys.</para> 45 <para>Any validating resolver which is configured to use the 46 active KSK as an RFC 5011-managed trust anchor will take note 47 of the stand-by KSKs in the zone's DNSKEY RRset, and store them 48 for future reference. The resolver will recheck the zone 49 periodically, and after 30 days, if the new key is still there, 50 then the key will be accepted by the resolver as a valid trust 51 anchor for the zone. Any time after this 30-day acceptance 52 timer has completed, the active KSK can be revoked, and the 53 zone can be "rolled over" to the newly accepted key.</para> 54 <para>The easiest way to place a stand-by key in a zone is to 55 use the "smart signing" features of 56 <command>dnssec-keygen</command> and 57 <command>dnssec-signzone</command>. If a key with a publication 58 date in the past, but an activation date which is unset or in 59 the future, " 60 <command>dnssec-signzone -S</command>" will include the DNSKEY 61 record in the zone, but will not sign with it:</para> 62 <screen> 63$ <userinput>dnssec-keygen -K keys -f KSK -P now -A now+2y example.net</userinput> 64$ <userinput>dnssec-signzone -S -K keys example.net</userinput> 65</screen> 66 <para>To revoke a key, the new command 67 <command>dnssec-revoke</command> has been added. This adds the 68 REVOKED bit to the key flags and re-generates the 69 <filename>K*.key</filename> and 70 <filename>K*.private</filename> files.</para> 71 <para>After revoking the active key, the zone must be signed 72 with both the revoked KSK and the new active KSK. (Smart 73 signing takes care of this automatically.)</para> 74 <para>Once a key has been revoked and used to sign the DNSKEY 75 RRset in which it appears, that key will never again be 76 accepted as a valid trust anchor by the resolver. However, 77 validation can proceed using the new active key (which had been 78 accepted by the resolver when it was a stand-by key).</para> 79 <para>See RFC 5011 for more details on key rollover 80 scenarios.</para> 81 <para>When a key has been revoked, its key ID changes, 82 increasing by 128, and wrapping around at 65535. So, for 83 example, the key "<filename>Kexample.com.+005+10000</filename>" becomes 84 "<filename>Kexample.com.+005+10128</filename>".</para> 85 <para>If two keys have ID's exactly 128 apart, and one is 86 revoked, then the two key ID's will collide, causing several 87 problems. To prevent this, 88 <command>dnssec-keygen</command> will not generate a new key if 89 another key is present which may collide. This checking will 90 only occur if the new keys are written to the same directory 91 which holds all other keys in use for that zone.</para> 92 <para>Older versions of BIND 9 did not have this precaution. 93 Exercise caution if using key revocation on keys that were 94 generated by previous releases, or if using keys stored in 95 multiple directories or on multiple machines.</para> 96 <para>It is expected that a future release of BIND 9 will 97 address this problem in a different way, by storing revoked 98 keys with their original unrevoked key ID's.</para> 99 </sect2> 100</sect1> 101