Bv9ARM.ch04.html revision 575e532437cf7f203707765e21767db92fa1e480
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7bff28e0cedd8656acd24b420759649184d8cf00vboxsync><TITLE
2291faee92ebb5cc9722cd3f22e499900a5a411fvboxsync>Advanced DNS Features</TITLE
7bff28e0cedd8656acd24b420759649184d8cf00vboxsync><META
9496b6f77d66eb89f088668752b8838d578d6e10vboxsyncNAME="GENERATOR"
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9496b6f77d66eb89f088668752b8838d578d6e10vboxsyncREL="HOME"
9496b6f77d66eb89f088668752b8838d578d6e10vboxsyncTITLE="BIND 9 Administrator Reference Manual"
9496b6f77d66eb89f088668752b8838d578d6e10vboxsyncHREF="Bv9ARM.html"><LINK
9496b6f77d66eb89f088668752b8838d578d6e10vboxsyncREL="PREVIOUS"
9496b6f77d66eb89f088668752b8838d578d6e10vboxsyncTITLE="Name Server Configuration"
7bff28e0cedd8656acd24b420759649184d8cf00vboxsyncHREF="Bv9ARM.ch03.html"><LINK
4b9d6701570cb98fd36e209314239d104ec584d3vboxsyncREL="NEXT"
4b9d6701570cb98fd36e209314239d104ec584d3vboxsyncTITLE="The BIND 9 Lightweight Resolver"
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ef1c003b45b1550236f47a2da7eea2e25f224b41vboxsync><DIV
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ef1c003b45b1550236f47a2da7eea2e25f224b41vboxsync><TABLE
ef1c003b45b1550236f47a2da7eea2e25f224b41vboxsyncSUMMARY="Header navigation table"
0486df2e670fa5d25ca947fd92b19dd54229692dvboxsyncWIDTH="100%"
0486df2e670fa5d25ca947fd92b19dd54229692dvboxsyncBORDER="0"
2c18e977ea3600677b8c58c9de0caa61792ba428vboxsyncCELLPADDING="0"
95714accc37694e6f4ae3c646dd01f3827c3d260vboxsyncCELLSPACING="0"
95714accc37694e6f4ae3c646dd01f3827c3d260vboxsync><TR
95714accc37694e6f4ae3c646dd01f3827c3d260vboxsync><TH
95714accc37694e6f4ae3c646dd01f3827c3d260vboxsyncCOLSPAN="3"
95714accc37694e6f4ae3c646dd01f3827c3d260vboxsyncALIGN="center"
95714accc37694e6f4ae3c646dd01f3827c3d260vboxsync>BIND 9 Administrator Reference Manual</TH
95714accc37694e6f4ae3c646dd01f3827c3d260vboxsync></TR
95714accc37694e6f4ae3c646dd01f3827c3d260vboxsync><TR
6cf17994e7631a6e8711c17848689c2064d5ccacvboxsync><TD
95714accc37694e6f4ae3c646dd01f3827c3d260vboxsyncWIDTH="10%"
95714accc37694e6f4ae3c646dd01f3827c3d260vboxsyncALIGN="left"
6cf17994e7631a6e8711c17848689c2064d5ccacvboxsyncVALIGN="bottom"
95714accc37694e6f4ae3c646dd01f3827c3d260vboxsync><A
95714accc37694e6f4ae3c646dd01f3827c3d260vboxsyncHREF="Bv9ARM.ch03.html"
95714accc37694e6f4ae3c646dd01f3827c3d260vboxsyncACCESSKEY="P"
95714accc37694e6f4ae3c646dd01f3827c3d260vboxsync>Prev</A
95714accc37694e6f4ae3c646dd01f3827c3d260vboxsync></TD
95714accc37694e6f4ae3c646dd01f3827c3d260vboxsync><TD
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a2f6500ea77004e215d6fc8fcdab25b1d4d1ad3dvboxsyncALIGN="center"
0c8b774aca1168c2007424a49f6fa159fc23e42bvboxsyncVALIGN="bottom"
0c8b774aca1168c2007424a49f6fa159fc23e42bvboxsync></TD
a2f6500ea77004e215d6fc8fcdab25b1d4d1ad3dvboxsync><TD
a2f6500ea77004e215d6fc8fcdab25b1d4d1ad3dvboxsyncWIDTH="10%"
a2f6500ea77004e215d6fc8fcdab25b1d4d1ad3dvboxsyncALIGN="right"
0c8b774aca1168c2007424a49f6fa159fc23e42bvboxsyncVALIGN="bottom"
7bff28e0cedd8656acd24b420759649184d8cf00vboxsync><A
771761cda2c81e899526a0dce22c8cd2510fff82vboxsyncHREF="Bv9ARM.ch05.html"
1826861f34e9be70b29cd5e1a6038caf9fbf37bevboxsyncACCESSKEY="N"
f2ba84c335a6e7ac91f69863ff51b10c65c9d40fvboxsync>Next</A
1826861f34e9be70b29cd5e1a6038caf9fbf37bevboxsync></TD
53e1c27c7564c45ad0b92676ddea561591a3e869vboxsync></TR
53e1c27c7564c45ad0b92676ddea561591a3e869vboxsync></TABLE
f2ba84c335a6e7ac91f69863ff51b10c65c9d40fvboxsync><HR
f2ba84c335a6e7ac91f69863ff51b10c65c9d40fvboxsyncALIGN="LEFT"
b459362b1c9b5ce5e6bf4ceb32ffe1294c08be07vboxsyncWIDTH="100%"></DIV
b459362b1c9b5ce5e6bf4ceb32ffe1294c08be07vboxsync><DIV
b459362b1c9b5ce5e6bf4ceb32ffe1294c08be07vboxsyncCLASS="chapter"
53e1c27c7564c45ad0b92676ddea561591a3e869vboxsync><H1
53e1c27c7564c45ad0b92676ddea561591a3e869vboxsync><A
b459362b1c9b5ce5e6bf4ceb32ffe1294c08be07vboxsyncNAME="ch04"
53e1c27c7564c45ad0b92676ddea561591a3e869vboxsync></A
f2ba84c335a6e7ac91f69863ff51b10c65c9d40fvboxsync>Chapter 4. Advanced DNS Features</H1
53e1c27c7564c45ad0b92676ddea561591a3e869vboxsync><DIV
53e1c27c7564c45ad0b92676ddea561591a3e869vboxsyncCLASS="TOC"
7bff28e0cedd8656acd24b420759649184d8cf00vboxsync><DL
0c8b774aca1168c2007424a49f6fa159fc23e42bvboxsync><DT
1826861f34e9be70b29cd5e1a6038caf9fbf37bevboxsync><B
0c8b774aca1168c2007424a49f6fa159fc23e42bvboxsync>Table of Contents</B
1826861f34e9be70b29cd5e1a6038caf9fbf37bevboxsync></DT
1826861f34e9be70b29cd5e1a6038caf9fbf37bevboxsync><DT
0c8b774aca1168c2007424a49f6fa159fc23e42bvboxsync>4.1. <A
0c8b774aca1168c2007424a49f6fa159fc23e42bvboxsyncHREF="Bv9ARM.ch04.html#notify"
0c8b774aca1168c2007424a49f6fa159fc23e42bvboxsync>Notify</A
0c8b774aca1168c2007424a49f6fa159fc23e42bvboxsync></DT
0c8b774aca1168c2007424a49f6fa159fc23e42bvboxsync><DT
0c8b774aca1168c2007424a49f6fa159fc23e42bvboxsync>4.2. <A
7bff28e0cedd8656acd24b420759649184d8cf00vboxsyncHREF="Bv9ARM.ch04.html#dynamic_update"
f2ba84c335a6e7ac91f69863ff51b10c65c9d40fvboxsync>Dynamic Update</A
f2ba84c335a6e7ac91f69863ff51b10c65c9d40fvboxsync></DT
f2ba84c335a6e7ac91f69863ff51b10c65c9d40fvboxsync><DT
41e3b5da61b49017cb647f2f32a231c524fc370avboxsync>4.3. <A
41e3b5da61b49017cb647f2f32a231c524fc370avboxsyncHREF="Bv9ARM.ch04.html#incremental_zone_transfers"
41e3b5da61b49017cb647f2f32a231c524fc370avboxsync>Incremental Zone Transfers (IXFR)</A
f2ba84c335a6e7ac91f69863ff51b10c65c9d40fvboxsync></DT
f2ba84c335a6e7ac91f69863ff51b10c65c9d40fvboxsync><DT
f2ba84c335a6e7ac91f69863ff51b10c65c9d40fvboxsync>4.4. <A
f2ba84c335a6e7ac91f69863ff51b10c65c9d40fvboxsyncHREF="Bv9ARM.ch04.html#AEN767"
f2ba84c335a6e7ac91f69863ff51b10c65c9d40fvboxsync>Split DNS</A
f2ba84c335a6e7ac91f69863ff51b10c65c9d40fvboxsync></DT
f2ba84c335a6e7ac91f69863ff51b10c65c9d40fvboxsync><DT
f2ba84c335a6e7ac91f69863ff51b10c65c9d40fvboxsync>4.5. <A
cfd41a3683178a30bac4417128b4673806653797vboxsyncHREF="Bv9ARM.ch04.html#tsig"
cfd41a3683178a30bac4417128b4673806653797vboxsync>TSIG</A
693d9f3305eb4a4684a6613b8a41a6fa150cc101vboxsync></DT
693d9f3305eb4a4684a6613b8a41a6fa150cc101vboxsync><DT
693d9f3305eb4a4684a6613b8a41a6fa150cc101vboxsync>4.6. <A
693d9f3305eb4a4684a6613b8a41a6fa150cc101vboxsyncHREF="Bv9ARM.ch04.html#AEN927"
77c85c820fe4467a0856134e0c9e5c5790cd847evboxsync>TKEY</A
77c85c820fe4467a0856134e0c9e5c5790cd847evboxsync></DT
77c85c820fe4467a0856134e0c9e5c5790cd847evboxsync><DT
77c85c820fe4467a0856134e0c9e5c5790cd847evboxsync>4.7. <A
77c85c820fe4467a0856134e0c9e5c5790cd847evboxsyncHREF="Bv9ARM.ch04.html#AEN942"
77c85c820fe4467a0856134e0c9e5c5790cd847evboxsync>SIG(0)</A
7bff28e0cedd8656acd24b420759649184d8cf00vboxsync></DT
613c0d015cbaef93be47fc03f0708744c5c24f79vboxsync><DT
f2ba84c335a6e7ac91f69863ff51b10c65c9d40fvboxsync>4.8. <A
f2ba84c335a6e7ac91f69863ff51b10c65c9d40fvboxsyncHREF="Bv9ARM.ch04.html#DNSSEC"
cefc5f2411cee3fe8071f6f99ed23a90f46b29f6vboxsync>DNSSEC</A
f2ba84c335a6e7ac91f69863ff51b10c65c9d40fvboxsync></DT
907ba2c9b3d1821f95be17115ecad9fe8a2cae02vboxsync><DT
77c85c820fe4467a0856134e0c9e5c5790cd847evboxsync>4.9. <A
77c85c820fe4467a0856134e0c9e5c5790cd847evboxsyncHREF="Bv9ARM.ch04.html#AEN1011"
693d9f3305eb4a4684a6613b8a41a6fa150cc101vboxsync>IPv6 Support in <ACRONYM
77c85c820fe4467a0856134e0c9e5c5790cd847evboxsyncCLASS="acronym"
77c85c820fe4467a0856134e0c9e5c5790cd847evboxsync>BIND</ACRONYM
693d9f3305eb4a4684a6613b8a41a6fa150cc101vboxsync> 9</A
77c85c820fe4467a0856134e0c9e5c5790cd847evboxsync></DT
771761cda2c81e899526a0dce22c8cd2510fff82vboxsync></DL
f6cc81e94c29cc9b39b896cf32ecfe0501b4a1e5vboxsync></DIV
a2f6500ea77004e215d6fc8fcdab25b1d4d1ad3dvboxsync><DIV
a2f6500ea77004e215d6fc8fcdab25b1d4d1ad3dvboxsyncCLASS="sect1"
a2f6500ea77004e215d6fc8fcdab25b1d4d1ad3dvboxsync><H1
a2f6500ea77004e215d6fc8fcdab25b1d4d1ad3dvboxsyncCLASS="sect1"
efbdd9fc22305720d20be7cc37b4f45f43146b09vboxsync><A
a2f6500ea77004e215d6fc8fcdab25b1d4d1ad3dvboxsyncNAME="notify"
9c59bcefe2993070fafaf0d6cee9673f48479128vboxsync>4.1. Notify</A
a2f6500ea77004e215d6fc8fcdab25b1d4d1ad3dvboxsync></H1
77c85c820fe4467a0856134e0c9e5c5790cd847evboxsync><P
9c59bcefe2993070fafaf0d6cee9673f48479128vboxsync><ACRONYM
a2f6500ea77004e215d6fc8fcdab25b1d4d1ad3dvboxsyncCLASS="acronym"
77c85c820fe4467a0856134e0c9e5c5790cd847evboxsync>DNS</ACRONYM
77c85c820fe4467a0856134e0c9e5c5790cd847evboxsync> NOTIFY is a mechanism that allows master
a2f6500ea77004e215d6fc8fcdab25b1d4d1ad3dvboxsyncservers to notify their slave servers of changes to a zone's data. In
77c85c820fe4467a0856134e0c9e5c5790cd847evboxsyncresponse to a <B
9c59bcefe2993070fafaf0d6cee9673f48479128vboxsyncCLASS="command"
9c59bcefe2993070fafaf0d6cee9673f48479128vboxsync>NOTIFY</B
77c85c820fe4467a0856134e0c9e5c5790cd847evboxsync> from a master server, the
77c85c820fe4467a0856134e0c9e5c5790cd847evboxsyncslave will check to see that its version of the zone is the
8f7119688865a134053bd580972655ce2b8954b3vboxsynccurrent version and, if not, initiate a zone transfer.</P
77c85c820fe4467a0856134e0c9e5c5790cd847evboxsync><P
77c85c820fe4467a0856134e0c9e5c5790cd847evboxsync><ACRONYM
77c85c820fe4467a0856134e0c9e5c5790cd847evboxsyncCLASS="acronym"
a2f6500ea77004e215d6fc8fcdab25b1d4d1ad3dvboxsync>DNS</ACRONYM
a2f6500ea77004e215d6fc8fcdab25b1d4d1ad3dvboxsync>
a2f6500ea77004e215d6fc8fcdab25b1d4d1ad3dvboxsyncFor more information about
a2f6500ea77004e215d6fc8fcdab25b1d4d1ad3dvboxsync<B
a2f6500ea77004e215d6fc8fcdab25b1d4d1ad3dvboxsyncCLASS="command"
a2f6500ea77004e215d6fc8fcdab25b1d4d1ad3dvboxsync>NOTIFY</B
77c85c820fe4467a0856134e0c9e5c5790cd847evboxsync>, see the description of the
77c85c820fe4467a0856134e0c9e5c5790cd847evboxsync<B
77c85c820fe4467a0856134e0c9e5c5790cd847evboxsyncCLASS="command"
8f7119688865a134053bd580972655ce2b8954b3vboxsync>notify</B
77c85c820fe4467a0856134e0c9e5c5790cd847evboxsync> option in <A
693d9f3305eb4a4684a6613b8a41a6fa150cc101vboxsyncHREF="Bv9ARM.ch06.html#boolean_options"
1826861f34e9be70b29cd5e1a6038caf9fbf37bevboxsync>Section 6.2.16.1</A
1826861f34e9be70b29cd5e1a6038caf9fbf37bevboxsync> and
1826861f34e9be70b29cd5e1a6038caf9fbf37bevboxsyncthe description of the zone option <B
77c85c820fe4467a0856134e0c9e5c5790cd847evboxsyncCLASS="command"
77c85c820fe4467a0856134e0c9e5c5790cd847evboxsync>also-notify</B
45eeaa1736817a425d69d35b3aa5f0dc38a7f7efvboxsync> in
693d9f3305eb4a4684a6613b8a41a6fa150cc101vboxsync<A
01f38d7bedc71f105edc6e67f8cbb9a0bf325442vboxsyncHREF="Bv9ARM.ch06.html#zone_transfers"
8f7119688865a134053bd580972655ce2b8954b3vboxsync>Section 6.2.16.7</A
62e5c2cfabb91397405d7bfe7908ec2b3a483831vboxsync>. The <B
62e5c2cfabb91397405d7bfe7908ec2b3a483831vboxsyncCLASS="command"
8f7119688865a134053bd580972655ce2b8954b3vboxsync>NOTIFY</B
8f7119688865a134053bd580972655ce2b8954b3vboxsync>
2c18e977ea3600677b8c58c9de0caa61792ba428vboxsyncprotocol is specified in RFC 1996.
2c18e977ea3600677b8c58c9de0caa61792ba428vboxsync</P
8f7119688865a134053bd580972655ce2b8954b3vboxsync></DIV
2c18e977ea3600677b8c58c9de0caa61792ba428vboxsync><DIV
2c18e977ea3600677b8c58c9de0caa61792ba428vboxsyncCLASS="sect1"
01f38d7bedc71f105edc6e67f8cbb9a0bf325442vboxsync><H1
01f38d7bedc71f105edc6e67f8cbb9a0bf325442vboxsyncCLASS="sect1"
01f38d7bedc71f105edc6e67f8cbb9a0bf325442vboxsync><A
01f38d7bedc71f105edc6e67f8cbb9a0bf325442vboxsyncNAME="dynamic_update"
01f38d7bedc71f105edc6e67f8cbb9a0bf325442vboxsync>4.2. Dynamic Update</A
693d9f3305eb4a4684a6613b8a41a6fa150cc101vboxsync></H1
8f7119688865a134053bd580972655ce2b8954b3vboxsync><P
8f7119688865a134053bd580972655ce2b8954b3vboxsync>Dynamic Update is a method for adding, replacing or deleting
8f7119688865a134053bd580972655ce2b8954b3vboxsync records in a master server by sending it a special form of DNS
693d9f3305eb4a4684a6613b8a41a6fa150cc101vboxsync messages. The format and meaning of these messages is specified
693d9f3305eb4a4684a6613b8a41a6fa150cc101vboxsync in RFC 2136.</P
693d9f3305eb4a4684a6613b8a41a6fa150cc101vboxsync><P
693d9f3305eb4a4684a6613b8a41a6fa150cc101vboxsync>Dynamic update is enabled on a zone-by-zone basis, by
693d9f3305eb4a4684a6613b8a41a6fa150cc101vboxsync including an <B
8f7119688865a134053bd580972655ce2b8954b3vboxsyncCLASS="command"
1826861f34e9be70b29cd5e1a6038caf9fbf37bevboxsync>allow-update</B
693d9f3305eb4a4684a6613b8a41a6fa150cc101vboxsync> or
1826861f34e9be70b29cd5e1a6038caf9fbf37bevboxsync <B
693d9f3305eb4a4684a6613b8a41a6fa150cc101vboxsyncCLASS="command"
ad27e1d5e48ca41245120c331cc88b50464813cevboxsync>update-policy</B
1826861f34e9be70b29cd5e1a6038caf9fbf37bevboxsync> clause in the
1826861f34e9be70b29cd5e1a6038caf9fbf37bevboxsync <B
693d9f3305eb4a4684a6613b8a41a6fa150cc101vboxsyncCLASS="command"
693d9f3305eb4a4684a6613b8a41a6fa150cc101vboxsync>zone</B
693d9f3305eb4a4684a6613b8a41a6fa150cc101vboxsync> statement.</P
8f7119688865a134053bd580972655ce2b8954b3vboxsync><P
693d9f3305eb4a4684a6613b8a41a6fa150cc101vboxsync>Updating of secure zones (zones using DNSSEC) follows
693d9f3305eb4a4684a6613b8a41a6fa150cc101vboxsync RFC 3007: RRSIG and NSEC records affected by updates are automatically
693d9f3305eb4a4684a6613b8a41a6fa150cc101vboxsync regenerated by the server using an online zone key.
693d9f3305eb4a4684a6613b8a41a6fa150cc101vboxsync Update authorization is based
ad27e1d5e48ca41245120c331cc88b50464813cevboxsync on transaction signatures and an explicit server policy.</P
693d9f3305eb4a4684a6613b8a41a6fa150cc101vboxsync><DIV
693d9f3305eb4a4684a6613b8a41a6fa150cc101vboxsyncCLASS="sect2"
693d9f3305eb4a4684a6613b8a41a6fa150cc101vboxsync><H2
77c85c820fe4467a0856134e0c9e5c5790cd847evboxsyncCLASS="sect2"
693d9f3305eb4a4684a6613b8a41a6fa150cc101vboxsync><A
693d9f3305eb4a4684a6613b8a41a6fa150cc101vboxsyncNAME="journal"
693d9f3305eb4a4684a6613b8a41a6fa150cc101vboxsync>4.2.1. The journal file</A
693d9f3305eb4a4684a6613b8a41a6fa150cc101vboxsync></H2
693d9f3305eb4a4684a6613b8a41a6fa150cc101vboxsync><P
693d9f3305eb4a4684a6613b8a41a6fa150cc101vboxsync>All changes made to a zone using dynamic update are stored
693d9f3305eb4a4684a6613b8a41a6fa150cc101vboxsync in the zone's journal file. This file is automatically created
693d9f3305eb4a4684a6613b8a41a6fa150cc101vboxsync by the server when when the first dynamic update takes place.
693d9f3305eb4a4684a6613b8a41a6fa150cc101vboxsync The name of the journal file is formed by appending the extension
693d9f3305eb4a4684a6613b8a41a6fa150cc101vboxsync <TT
693d9f3305eb4a4684a6613b8a41a6fa150cc101vboxsyncCLASS="filename"
693d9f3305eb4a4684a6613b8a41a6fa150cc101vboxsync>.jnl</TT
693d9f3305eb4a4684a6613b8a41a6fa150cc101vboxsync> to the name of the corresponding zone
693d9f3305eb4a4684a6613b8a41a6fa150cc101vboxsync file unless specifically overridden. The journal file is in a
693d9f3305eb4a4684a6613b8a41a6fa150cc101vboxsync binary format and should not be edited manually.</P
693d9f3305eb4a4684a6613b8a41a6fa150cc101vboxsync><P
693d9f3305eb4a4684a6613b8a41a6fa150cc101vboxsync>The server will also occasionally write ("dump")
693d9f3305eb4a4684a6613b8a41a6fa150cc101vboxsync the complete contents of the updated zone to its zone file.
693d9f3305eb4a4684a6613b8a41a6fa150cc101vboxsync This is not done immediately after
693d9f3305eb4a4684a6613b8a41a6fa150cc101vboxsync each dynamic update, because that would be too slow when a large
933606e7609b250f207a2f97112f8388f88998c1vboxsync zone is updated frequently. Instead, the dump is delayed by
8f7119688865a134053bd580972655ce2b8954b3vboxsync up to 15 minutes, allowing additional updates to take place.</P
933606e7609b250f207a2f97112f8388f88998c1vboxsync><P
77c85c820fe4467a0856134e0c9e5c5790cd847evboxsync>When a server is restarted after a shutdown or crash, it will replay
77c85c820fe4467a0856134e0c9e5c5790cd847evboxsync the journal file to incorporate into the zone any updates that took
7bff28e0cedd8656acd24b420759649184d8cf00vboxsync place after the last zone dump.</P
9ced981a0263f6280ccbf5dc64c0e81fbe4a2fdavboxsync><P
77c85c820fe4467a0856134e0c9e5c5790cd847evboxsync>Changes that result from incoming incremental zone transfers are also
77c85c820fe4467a0856134e0c9e5c5790cd847evboxsync journalled in a similar way.</P
77c85c820fe4467a0856134e0c9e5c5790cd847evboxsync><P
1ace73711fa06807748eff26632c7273a1f7c2dbvboxsync>The zone files of dynamic zones cannot normally be edited by
1ace73711fa06807748eff26632c7273a1f7c2dbvboxsync hand because they are not guaranteed to contain the most recent
1ace73711fa06807748eff26632c7273a1f7c2dbvboxsync dynamic changes - those are only in the journal file.
1ace73711fa06807748eff26632c7273a1f7c2dbvboxsync The only way to ensure that the zone file of a dynamic zone
1ace73711fa06807748eff26632c7273a1f7c2dbvboxsync is up to date is to run <B
1ace73711fa06807748eff26632c7273a1f7c2dbvboxsyncCLASS="command"
77c85c820fe4467a0856134e0c9e5c5790cd847evboxsync>rndc stop</B
77c85c820fe4467a0856134e0c9e5c5790cd847evboxsync>.</P
1ace73711fa06807748eff26632c7273a1f7c2dbvboxsync><P
1ace73711fa06807748eff26632c7273a1f7c2dbvboxsync>If you have to make changes to a dynamic zone
1ace73711fa06807748eff26632c7273a1f7c2dbvboxsync manually, the following procedure will work: Disable dynamic updates
5f9ec43969b9ba00f6c2d03bafc9ac36a41c95e1vboxsync to the zone using
5f9ec43969b9ba00f6c2d03bafc9ac36a41c95e1vboxsync <B
1ace73711fa06807748eff26632c7273a1f7c2dbvboxsyncCLASS="command"
5f9ec43969b9ba00f6c2d03bafc9ac36a41c95e1vboxsync>rndc freeze <VAR
5f9ec43969b9ba00f6c2d03bafc9ac36a41c95e1vboxsyncCLASS="replaceable"
5f9ec43969b9ba00f6c2d03bafc9ac36a41c95e1vboxsync>zone</VAR
5f9ec43969b9ba00f6c2d03bafc9ac36a41c95e1vboxsync></B
5f9ec43969b9ba00f6c2d03bafc9ac36a41c95e1vboxsync>.
5f9ec43969b9ba00f6c2d03bafc9ac36a41c95e1vboxsync This will also remove the zone's <TT
5f9ec43969b9ba00f6c2d03bafc9ac36a41c95e1vboxsyncCLASS="filename"
5f9ec43969b9ba00f6c2d03bafc9ac36a41c95e1vboxsync>.jnl</TT
5f9ec43969b9ba00f6c2d03bafc9ac36a41c95e1vboxsync> file
77c85c820fe4467a0856134e0c9e5c5790cd847evboxsync and update the master file. Edit the zone file. Run
9ced981a0263f6280ccbf5dc64c0e81fbe4a2fdavboxsync <B
e12a6ea07ddb7a02b3575e78b24960e13f42bf4cvboxsyncCLASS="command"
9ced981a0263f6280ccbf5dc64c0e81fbe4a2fdavboxsync>rndc unfreeze <VAR
9ced981a0263f6280ccbf5dc64c0e81fbe4a2fdavboxsyncCLASS="replaceable"
77c85c820fe4467a0856134e0c9e5c5790cd847evboxsync>zone</VAR
53e1c27c7564c45ad0b92676ddea561591a3e869vboxsync></B
53e1c27c7564c45ad0b92676ddea561591a3e869vboxsync>
1d258b8772ee104b5fab3d1743eabc2f5cfe2fa4vboxsync to reload the changed zone and re-enable dynamic updates.</P
1d258b8772ee104b5fab3d1743eabc2f5cfe2fa4vboxsync></DIV
53e1c27c7564c45ad0b92676ddea561591a3e869vboxsync></DIV
1d258b8772ee104b5fab3d1743eabc2f5cfe2fa4vboxsync><DIV
1d258b8772ee104b5fab3d1743eabc2f5cfe2fa4vboxsyncCLASS="sect1"
53e1c27c7564c45ad0b92676ddea561591a3e869vboxsync><H1
53e1c27c7564c45ad0b92676ddea561591a3e869vboxsyncCLASS="sect1"
53e1c27c7564c45ad0b92676ddea561591a3e869vboxsync><A
53e1c27c7564c45ad0b92676ddea561591a3e869vboxsyncNAME="incremental_zone_transfers"
1d258b8772ee104b5fab3d1743eabc2f5cfe2fa4vboxsync>4.3. Incremental Zone Transfers (IXFR)</A
1826861f34e9be70b29cd5e1a6038caf9fbf37bevboxsync></H1
1d258b8772ee104b5fab3d1743eabc2f5cfe2fa4vboxsync><P
1d258b8772ee104b5fab3d1743eabc2f5cfe2fa4vboxsync>The incremental zone transfer (IXFR) protocol is a way for
1d258b8772ee104b5fab3d1743eabc2f5cfe2fa4vboxsyncslave servers to transfer only changed data, instead of having to
1d258b8772ee104b5fab3d1743eabc2f5cfe2fa4vboxsynctransfer the entire zone. The IXFR protocol is specified in RFC
1d258b8772ee104b5fab3d1743eabc2f5cfe2fa4vboxsync1995. See <A
53e1c27c7564c45ad0b92676ddea561591a3e869vboxsyncHREF="Bv9ARM.ch09.html#proposed_standards"
53e1c27c7564c45ad0b92676ddea561591a3e869vboxsync>Proposed Standards</A
53e1c27c7564c45ad0b92676ddea561591a3e869vboxsync>.</P
1826861f34e9be70b29cd5e1a6038caf9fbf37bevboxsync><P
1826861f34e9be70b29cd5e1a6038caf9fbf37bevboxsync>When acting as a master, <ACRONYM
1d258b8772ee104b5fab3d1743eabc2f5cfe2fa4vboxsyncCLASS="acronym"
1826861f34e9be70b29cd5e1a6038caf9fbf37bevboxsync>BIND</ACRONYM
1826861f34e9be70b29cd5e1a6038caf9fbf37bevboxsync> 9
1826861f34e9be70b29cd5e1a6038caf9fbf37bevboxsyncsupports IXFR for those zones
1826861f34e9be70b29cd5e1a6038caf9fbf37bevboxsyncwhere the necessary change history information is available. These
53e1c27c7564c45ad0b92676ddea561591a3e869vboxsyncinclude master zones maintained by dynamic update and slave zones
53e1c27c7564c45ad0b92676ddea561591a3e869vboxsyncwhose data was obtained by IXFR. For manually maintained master
674c51d0cb8c72a2852b315b70f76d11d82b20f5vboxsynczones, and for slave zones obtained by performing a full zone
674c51d0cb8c72a2852b315b70f76d11d82b20f5vboxsynctransfer (AXFR), IXFR is supported only if the option
674c51d0cb8c72a2852b315b70f76d11d82b20f5vboxsync<B
674c51d0cb8c72a2852b315b70f76d11d82b20f5vboxsyncCLASS="command"
674c51d0cb8c72a2852b315b70f76d11d82b20f5vboxsync>ixfr-from-differences</B
e12a6ea07ddb7a02b3575e78b24960e13f42bf4cvboxsync> is set
77c85c820fe4467a0856134e0c9e5c5790cd847evboxsyncto <KBD
77c85c820fe4467a0856134e0c9e5c5790cd847evboxsyncCLASS="userinput"
77c85c820fe4467a0856134e0c9e5c5790cd847evboxsync>yes</KBD
77c85c820fe4467a0856134e0c9e5c5790cd847evboxsync>.
77c85c820fe4467a0856134e0c9e5c5790cd847evboxsync</P
77c85c820fe4467a0856134e0c9e5c5790cd847evboxsync><P
53e1c27c7564c45ad0b92676ddea561591a3e869vboxsync>When acting as a slave, <ACRONYM
77c85c820fe4467a0856134e0c9e5c5790cd847evboxsyncCLASS="acronym"
77c85c820fe4467a0856134e0c9e5c5790cd847evboxsync>BIND</ACRONYM
77c85c820fe4467a0856134e0c9e5c5790cd847evboxsync> 9 will
77c85c820fe4467a0856134e0c9e5c5790cd847evboxsyncattempt to use IXFR unless
77c85c820fe4467a0856134e0c9e5c5790cd847evboxsyncit is explicitly disabled. For more information about disabling
6e3cc82d5d5effda92c9fec18b870d54386f99favboxsyncIXFR, see the description of the <B
6e3cc82d5d5effda92c9fec18b870d54386f99favboxsyncCLASS="command"
e27467c77543dda00047807bdd69b62f1cd50feevboxsync>request-ixfr</B
e27467c77543dda00047807bdd69b62f1cd50feevboxsync> clause
771761cda2c81e899526a0dce22c8cd2510fff82vboxsyncof the <B
771761cda2c81e899526a0dce22c8cd2510fff82vboxsyncCLASS="command"
7bff28e0cedd8656acd24b420759649184d8cf00vboxsync>server</B
7bff28e0cedd8656acd24b420759649184d8cf00vboxsync> statement.</P
9ced981a0263f6280ccbf5dc64c0e81fbe4a2fdavboxsync></DIV
f2ba84c335a6e7ac91f69863ff51b10c65c9d40fvboxsync><DIV
f2ba84c335a6e7ac91f69863ff51b10c65c9d40fvboxsyncCLASS="sect1"
9a1578b66f9e563cf99c75ffa881db476f477e3avboxsync><H1
8f7119688865a134053bd580972655ce2b8954b3vboxsyncCLASS="sect1"
8f7119688865a134053bd580972655ce2b8954b3vboxsync><A
bc8ea11359bbfdee1aa1a32821d263292d4a8feevboxsyncNAME="AEN767"
bc8ea11359bbfdee1aa1a32821d263292d4a8feevboxsync>4.4. Split DNS</A
bc8ea11359bbfdee1aa1a32821d263292d4a8feevboxsync></H1
bc8ea11359bbfdee1aa1a32821d263292d4a8feevboxsync><P
bc8ea11359bbfdee1aa1a32821d263292d4a8feevboxsync>Setting up different views, or visibility, of the DNS space to
bc8ea11359bbfdee1aa1a32821d263292d4a8feevboxsyncinternal and external resolvers is usually referred to as a <SPAN
bc8ea11359bbfdee1aa1a32821d263292d4a8feevboxsyncCLASS="emphasis"
bc8ea11359bbfdee1aa1a32821d263292d4a8feevboxsync><I
bc8ea11359bbfdee1aa1a32821d263292d4a8feevboxsyncCLASS="emphasis"
8f7119688865a134053bd580972655ce2b8954b3vboxsync>Split
8f7119688865a134053bd580972655ce2b8954b3vboxsyncDNS</I
bc8ea11359bbfdee1aa1a32821d263292d4a8feevboxsync></SPAN
bc8ea11359bbfdee1aa1a32821d263292d4a8feevboxsync> setup. There are several reasons an organization
bc8ea11359bbfdee1aa1a32821d263292d4a8feevboxsyncwould want to set up its DNS this way.</P
bc8ea11359bbfdee1aa1a32821d263292d4a8feevboxsync><P
bc8ea11359bbfdee1aa1a32821d263292d4a8feevboxsync>One common reason for setting up a DNS system this way is
bc8ea11359bbfdee1aa1a32821d263292d4a8feevboxsyncto hide "internal" DNS information from "external" clients on the
bc8ea11359bbfdee1aa1a32821d263292d4a8feevboxsyncInternet. There is some debate as to whether or not this is actually useful.
bc8ea11359bbfdee1aa1a32821d263292d4a8feevboxsyncInternal DNS information leaks out in many ways (via email headers,
8f7119688865a134053bd580972655ce2b8954b3vboxsyncfor example) and most savvy "attackers" can find the information
bc8ea11359bbfdee1aa1a32821d263292d4a8feevboxsyncthey need using other means.</P
bc8ea11359bbfdee1aa1a32821d263292d4a8feevboxsync><P
8f7119688865a134053bd580972655ce2b8954b3vboxsync>Another common reason for setting up a Split DNS system is
bc8ea11359bbfdee1aa1a32821d263292d4a8feevboxsyncto allow internal networks that are behind filters or in RFC 1918
8f7119688865a134053bd580972655ce2b8954b3vboxsyncspace (reserved IP space, as documented in RFC 1918) to resolve DNS
bc8ea11359bbfdee1aa1a32821d263292d4a8feevboxsyncon the Internet. Split DNS can also be used to allow mail from outside
8f7119688865a134053bd580972655ce2b8954b3vboxsyncback in to the internal network.</P
bc8ea11359bbfdee1aa1a32821d263292d4a8feevboxsync><P
bc8ea11359bbfdee1aa1a32821d263292d4a8feevboxsync>Here is an example of a split DNS setup:</P
bc8ea11359bbfdee1aa1a32821d263292d4a8feevboxsync><P
bc8ea11359bbfdee1aa1a32821d263292d4a8feevboxsync>Let's say a company named <SPAN
9b5e4e8f5c00e8cd2289a73d173c96e551c79397vboxsyncCLASS="emphasis"
f2ba84c335a6e7ac91f69863ff51b10c65c9d40fvboxsync><I
f2ba84c335a6e7ac91f69863ff51b10c65c9d40fvboxsyncCLASS="emphasis"
f2ba84c335a6e7ac91f69863ff51b10c65c9d40fvboxsync>Example, Inc.</I
f2ba84c335a6e7ac91f69863ff51b10c65c9d40fvboxsync></SPAN
f2ba84c335a6e7ac91f69863ff51b10c65c9d40fvboxsync>
f2ba84c335a6e7ac91f69863ff51b10c65c9d40fvboxsync(<VAR
f2ba84c335a6e7ac91f69863ff51b10c65c9d40fvboxsyncCLASS="literal"
f2ba84c335a6e7ac91f69863ff51b10c65c9d40fvboxsync>example.com</VAR
f2ba84c335a6e7ac91f69863ff51b10c65c9d40fvboxsync>)
d95b7fbc09277b5375b98812fa76b08c6ce8535cvboxsynchas several corporate sites that have an internal network with reserved
f2ba84c335a6e7ac91f69863ff51b10c65c9d40fvboxsyncInternet Protocol (IP) space and an external demilitarized zone (DMZ),
d95b7fbc09277b5375b98812fa76b08c6ce8535cvboxsyncor "outside" section of a network, that is available to the public.</P
d95b7fbc09277b5375b98812fa76b08c6ce8535cvboxsync><P
d95b7fbc09277b5375b98812fa76b08c6ce8535cvboxsync><SPAN
f2ba84c335a6e7ac91f69863ff51b10c65c9d40fvboxsyncCLASS="emphasis"
7bff28e0cedd8656acd24b420759649184d8cf00vboxsync><I
97674677e4f2aeae576c39f966568dd664ba7979vboxsyncCLASS="emphasis"
77c85c820fe4467a0856134e0c9e5c5790cd847evboxsync>Example, Inc.</I
77c85c820fe4467a0856134e0c9e5c5790cd847evboxsync></SPAN
77c85c820fe4467a0856134e0c9e5c5790cd847evboxsync> wants its internal clients
72f66530e1bf87aa6894a5f55f1b4d36caa5761fvboxsyncto be able to resolve external hostnames and to exchange mail with
97674677e4f2aeae576c39f966568dd664ba7979vboxsyncpeople on the outside. The company also wants its internal resolvers
97674677e4f2aeae576c39f966568dd664ba7979vboxsyncto have access to certain internal-only zones that are not available
7bff28e0cedd8656acd24b420759649184d8cf00vboxsyncat all outside of the internal network.</P
><P
>In order to accomplish this, the company will set up two sets
of name servers. One set will be on the inside network (in the reserved
IP space) and the other set will be on bastion hosts, which are "proxy"
hosts that can talk to both sides of its network, in the DMZ.</P
><P
>The internal servers will be configured to forward all queries,
except queries for <TT
CLASS="filename"
>site1.internal</TT
>, <TT
CLASS="filename"
>site2.internal</TT
>, <TT
CLASS="filename"
>site1.example.com</TT
>,
and <TT
CLASS="filename"
>site2.example.com</TT
>, to the servers in the
DMZ. These internal servers will have complete sets of information
for <TT
CLASS="filename"
>site1.example.com</TT
>, <TT
CLASS="filename"
>site2.example.com</TT
>,<SPAN
CLASS="emphasis"
><I
CLASS="emphasis"
> </I
></SPAN
><TT
CLASS="filename"
>site1.internal</TT
>,
and <TT
CLASS="filename"
>site2.internal</TT
>.</P
><P
>To protect the <TT
CLASS="filename"
>site1.internal</TT
> and <TT
CLASS="filename"
>site2.internal</TT
> domains,
the internal name servers must be configured to disallow all queries
to these domains from any external hosts, including the bastion
hosts.</P
><P
>The external servers, which are on the bastion hosts, will
be configured to serve the "public" version of the <TT
CLASS="filename"
>site1</TT
> and <TT
CLASS="filename"
>site2.example.com</TT
> zones.
This could include things such as the host records for public servers
(<TT
CLASS="filename"
>www.example.com</TT
> and <TT
CLASS="filename"
>ftp.example.com</TT
>),
and mail exchange (MX) records (<TT
CLASS="filename"
>a.mx.example.com</TT
> and <TT
CLASS="filename"
>b.mx.example.com</TT
>).</P
><P
>In addition, the public <TT
CLASS="filename"
>site1</TT
> and <TT
CLASS="filename"
>site2.example.com</TT
> zones
should have special MX records that contain wildcard (`*') records
pointing to the bastion hosts. This is needed because external mail
servers do not have any other way of looking up how to deliver mail
to those internal hosts. With the wildcard records, the mail will
be delivered to the bastion host, which can then forward it on to
internal hosts.</P
><P
>Here's an example of a wildcard MX record:</P
><PRE
CLASS="programlisting"
><VAR
CLASS="literal"
>* IN MX 10 external1.example.com.</VAR
></PRE
><P
>Now that they accept mail on behalf of anything in the internal
network, the bastion hosts will need to know how to deliver mail
to internal hosts. In order for this to work properly, the resolvers on
the bastion hosts will need to be configured to point to the internal
name servers for DNS resolution.</P
><P
>Queries for internal hostnames will be answered by the internal
servers, and queries for external hostnames will be forwarded back
out to the DNS servers on the bastion hosts.</P
><P
>In order for all this to work properly, internal clients will
need to be configured to query <SPAN
CLASS="emphasis"
><I
CLASS="emphasis"
>only</I
></SPAN
> the internal
name servers for DNS queries. This could also be enforced via selective
filtering on the network.</P
><P
>If everything has been set properly, <SPAN
CLASS="emphasis"
><I
CLASS="emphasis"
>Example, Inc.</I
></SPAN
>'s
internal clients will now be able to:</P
><P
></P
><UL
><LI
><P
>Look up any hostnames in the <VAR
CLASS="literal"
>site1</VAR
> and
<VAR
CLASS="literal"
>site2.example.com</VAR
> zones.</P
></LI
><LI
><P
>Look up any hostnames in the <VAR
CLASS="literal"
>site1.internal</VAR
> and
<VAR
CLASS="literal"
>site2.internal</VAR
> domains.</P
></LI
><LI
><P
>Look up any hostnames on the Internet.</P
></LI
><LI
><P
>Exchange mail with internal AND external people.</P
></LI
></UL
><P
>Hosts on the Internet will be able to:</P
><P
></P
><UL
><LI
><P
>Look up any hostnames in the <VAR
CLASS="literal"
>site1</VAR
> and
<VAR
CLASS="literal"
>site2.example.com</VAR
> zones.</P
></LI
><LI
><P
>Exchange mail with anyone in the <VAR
CLASS="literal"
>site1</VAR
> and
<VAR
CLASS="literal"
>site2.example.com</VAR
> zones.</P
></LI
></UL
><P
>Here is an example configuration for the setup we just
described above. Note that this is only configuration information;
for information on how to configure your zone files, see <A
HREF="Bv9ARM.ch03.html#sample_configuration"
>Section 3.1</A
></P
><P
>Internal DNS server config:</P
><PRE
CLASS="programlisting"
>&#13;
acl internals { 172.16.72.0/24; 192.168.1.0/24; };
acl externals { <VAR
CLASS="varname"
>bastion-ips-go-here</VAR
>; };
options {
...
...
forward only;
forwarders { // forward to external servers
<VAR
CLASS="varname"
>bastion-ips-go-here</VAR
>;
};
allow-transfer { none; }; // sample allow-transfer (no one)
allow-query { internals; externals; }; // restrict query access
allow-recursion { internals; }; // restrict recursion
...
...
};
zone "site1.example.com" { // sample master zone
type master;
file "m/site1.example.com";
forwarders { }; // do normal iterative
// resolution (do not forward)
allow-query { internals; externals; };
allow-transfer { internals; };
};
zone "site2.example.com" { // sample slave zone
type slave;
file "s/site2.example.com";
masters { 172.16.72.3; };
forwarders { };
allow-query { internals; externals; };
allow-transfer { internals; };
};
zone "site1.internal" {
type master;
file "m/site1.internal";
forwarders { };
allow-query { internals; };
allow-transfer { internals; }
};
zone "site2.internal" {
type slave;
file "s/site2.internal";
masters { 172.16.72.3; };
forwarders { };
allow-query { internals };
allow-transfer { internals; }
};
</PRE
><P
>External (bastion host) DNS server config:</P
><PRE
CLASS="programlisting"
>&#13;acl internals { 172.16.72.0/24; 192.168.1.0/24; };
acl externals { bastion-ips-go-here; };
options {
...
...
allow-transfer { none; }; // sample allow-transfer (no one)
allow-query { any; }; // default query access
allow-query-cache { internals; externals; }; // restrict cache access
allow-recursion { internals; externals; }; // restrict recursion
...
...
};
zone "site1.example.com" { // sample slave zone
type master;
file "m/site1.foo.com";
allow-transfer { internals; externals; };
};
zone "site2.example.com" {
type slave;
file "s/site2.foo.com";
masters { another_bastion_host_maybe; };
allow-transfer { internals; externals; }
};
</PRE
><P
>In the <TT
CLASS="filename"
>resolv.conf</TT
> (or equivalent) on
the bastion host(s):</P
><PRE
CLASS="programlisting"
>&#13;search ...
nameserver 172.16.72.2
nameserver 172.16.72.3
nameserver 172.16.72.4
</PRE
></DIV
><DIV
CLASS="sect1"
><H1
CLASS="sect1"
><A
NAME="tsig"
>4.5. TSIG</A
></H1
><P
>This is a short guide to setting up Transaction SIGnatures
(TSIG) based transaction security in <ACRONYM
CLASS="acronym"
>BIND</ACRONYM
>. It describes changes
to the configuration file as well as what changes are required for
different features, including the process of creating transaction
keys and using transaction signatures with <ACRONYM
CLASS="acronym"
>BIND</ACRONYM
>.</P
><P
><ACRONYM
CLASS="acronym"
>BIND</ACRONYM
> primarily supports TSIG for server to server communication.
This includes zone transfer, notify, and recursive query messages.
Resolvers based on newer versions of <ACRONYM
CLASS="acronym"
>BIND</ACRONYM
> 8 have limited support
for TSIG.</P
><P
>TSIG might be most useful for dynamic update. A primary
server for a dynamic zone should use access control to control
updates, but IP-based access control is insufficient.
The cryptographic access control provided by TSIG
is far superior. The <B
CLASS="command"
>nsupdate</B
>
program supports TSIG via the <VAR
CLASS="option"
>-k</VAR
> and
<VAR
CLASS="option"
>-y</VAR
> command line options.</P
><DIV
CLASS="sect2"
><H2
CLASS="sect2"
><A
NAME="AEN858"
>4.5.1. Generate Shared Keys for Each Pair of Hosts</A
></H2
><P
>A shared secret is generated to be shared between <SPAN
CLASS="emphasis"
><I
CLASS="emphasis"
>host1</I
></SPAN
> and <SPAN
CLASS="emphasis"
><I
CLASS="emphasis"
>host2</I
></SPAN
>.
An arbitrary key name is chosen: "host1-host2.". The key name must
be the same on both hosts.</P
><DIV
CLASS="sect3"
><H3
CLASS="sect3"
><A
NAME="AEN863"
>4.5.1.1. Automatic Generation</A
></H3
><P
>The following command will generate a 128 bit (16 byte) HMAC-MD5
key as described above. Longer keys are better, but shorter keys
are easier to read. Note that the maximum key length is 512 bits;
keys longer than that will be digested with MD5 to produce a 128
bit key.</P
><P
><KBD
CLASS="userinput"
>dnssec-keygen -a hmac-md5 -b 128 -n HOST host1-host2.</KBD
></P
><P
>The key is in the file <TT
CLASS="filename"
>Khost1-host2.+157+00000.private</TT
>.
Nothing directly uses this file, but the base-64 encoded string
following "<VAR
CLASS="literal"
>Key:</VAR
>"
can be extracted from the file and used as a shared secret:</P
><PRE
CLASS="programlisting"
>Key: La/E5CjG9O+os1jq0a2jdA==</PRE
><P
>The string "<VAR
CLASS="literal"
>La/E5CjG9O+os1jq0a2jdA==</VAR
>" can
be used as the shared secret.</P
></DIV
><DIV
CLASS="sect3"
><H3
CLASS="sect3"
><A
NAME="AEN874"
>4.5.1.2. Manual Generation</A
></H3
><P
>The shared secret is simply a random sequence of bits, encoded
in base-64. Most ASCII strings are valid base-64 strings (assuming
the length is a multiple of 4 and only valid characters are used),
so the shared secret can be manually generated.</P
><P
>Also, a known string can be run through <B
CLASS="command"
>mmencode</B
> or
a similar program to generate base-64 encoded data.</P
></DIV
></DIV
><DIV
CLASS="sect2"
><H2
CLASS="sect2"
><A
NAME="AEN879"
>4.5.2. Copying the Shared Secret to Both Machines</A
></H2
><P
>This is beyond the scope of DNS. A secure transport mechanism
should be used. This could be secure FTP, ssh, telephone, etc.</P
></DIV
><DIV
CLASS="sect2"
><H2
CLASS="sect2"
><A
NAME="AEN882"
>4.5.3. Informing the Servers of the Key's Existence</A
></H2
><P
>Imagine <SPAN
CLASS="emphasis"
><I
CLASS="emphasis"
>host1</I
></SPAN
> and <SPAN
CLASS="emphasis"
><I
CLASS="emphasis"
>host 2</I
></SPAN
> are
both servers. The following is added to each server's <TT
CLASS="filename"
>named.conf</TT
> file:</P
><PRE
CLASS="programlisting"
>&#13;key host1-host2. {
algorithm hmac-md5;
secret "La/E5CjG9O+os1jq0a2jdA==";
};
</PRE
><P
>The algorithm, hmac-md5, is the only one supported by <ACRONYM
CLASS="acronym"
>BIND</ACRONYM
>.
The secret is the one generated above. Since this is a secret, it
is recommended that either <TT
CLASS="filename"
>named.conf</TT
> be non-world
readable, or the key directive be added to a non-world readable
file that is included by <TT
CLASS="filename"
>named.conf</TT
>.</P
><P
>At this point, the key is recognized. This means that if the
server receives a message signed by this key, it can verify the
signature. If the signature is successfully verified, the
response is signed by the same key.</P
></DIV
><DIV
CLASS="sect2"
><H2
CLASS="sect2"
><A
NAME="AEN894"
>4.5.4. Instructing the Server to Use the Key</A
></H2
><P
>Since keys are shared between two hosts only, the server must
be told when keys are to be used. The following is added to the <TT
CLASS="filename"
>named.conf</TT
> file
for <SPAN
CLASS="emphasis"
><I
CLASS="emphasis"
>host1</I
></SPAN
>, if the IP address of <SPAN
CLASS="emphasis"
><I
CLASS="emphasis"
>host2</I
></SPAN
> is
10.1.2.3:</P
><PRE
CLASS="programlisting"
>&#13;server 10.1.2.3 {
keys { host1-host2. ;};
};
</PRE
><P
>Multiple keys may be present, but only the first is used.
This directive does not contain any secrets, so it may be in a world-readable
file.</P
><P
>If <SPAN
CLASS="emphasis"
><I
CLASS="emphasis"
>host1</I
></SPAN
> sends a message that is a request
to that address, the message will be signed with the specified key. <SPAN
CLASS="emphasis"
><I
CLASS="emphasis"
>host1</I
></SPAN
> will
expect any responses to signed messages to be signed with the same
key.</P
><P
>A similar statement must be present in <SPAN
CLASS="emphasis"
><I
CLASS="emphasis"
>host2</I
></SPAN
>'s
configuration file (with <SPAN
CLASS="emphasis"
><I
CLASS="emphasis"
>host1</I
></SPAN
>'s address) for <SPAN
CLASS="emphasis"
><I
CLASS="emphasis"
>host2</I
></SPAN
> to
sign request messages to <SPAN
CLASS="emphasis"
><I
CLASS="emphasis"
>host1</I
></SPAN
>.</P
></DIV
><DIV
CLASS="sect2"
><H2
CLASS="sect2"
><A
NAME="AEN910"
>4.5.5. TSIG Key Based Access Control</A
></H2
><P
><ACRONYM
CLASS="acronym"
>BIND</ACRONYM
> allows IP addresses and ranges to be specified in ACL
definitions and
<B
CLASS="command"
>allow-{ query | transfer | update }</B
> directives.
This has been extended to allow TSIG keys also. The above key would
be denoted <B
CLASS="command"
>key host1-host2.</B
></P
><P
>An example of an allow-update directive would be:</P
><PRE
CLASS="programlisting"
>&#13;allow-update { key host1-host2. ;};
</PRE
><P
>This allows dynamic updates to succeed only if the request
was signed by a key named
"<B
CLASS="command"
>host1-host2.</B
>".</P
><P
>You may want to read about the more
powerful <B
CLASS="command"
>update-policy</B
> statement in <A
HREF="Bv9ARM.ch06.html#dynamic_update_policies"
>Section 6.2.24.4</A
>.</P
></DIV
><DIV
CLASS="sect2"
><H2
CLASS="sect2"
><A
NAME="AEN923"
>4.5.6. Errors</A
></H2
><P
>The processing of TSIG signed messages can result in
several errors. If a signed message is sent to a non-TSIG aware
server, a FORMERR will be returned, since the server will not
understand the record. This is a result of misconfiguration,
since the server must be explicitly configured to send a TSIG
signed message to a specific server.</P
><P
>If a TSIG aware server receives a message signed by an
unknown key, the response will be unsigned with the TSIG
extended error code set to BADKEY. If a TSIG aware server
receives a message with a signature that does not validate, the
response will be unsigned with the TSIG extended error code set
to BADSIG. If a TSIG aware server receives a message with a time
outside of the allowed range, the response will be signed with
the TSIG extended error code set to BADTIME, and the time values
will be adjusted so that the response can be successfully
verified. In any of these cases, the message's rcode is set to
NOTAUTH.</P
></DIV
></DIV
><DIV
CLASS="sect1"
><H1
CLASS="sect1"
><A
NAME="AEN927"
>4.6. TKEY</A
></H1
><P
><B
CLASS="command"
>TKEY</B
> is a mechanism for automatically
generating a shared secret between two hosts. There are several
"modes" of <B
CLASS="command"
>TKEY</B
> that specify how the key is
generated or assigned. <ACRONYM
CLASS="acronym"
>BIND</ACRONYM
> 9
implements only one of these modes,
the Diffie-Hellman key exchange. Both hosts are required to have
a Diffie-Hellman KEY record (although this record is not required
to be present in a zone). The <B
CLASS="command"
>TKEY</B
> process
must use signed messages, signed either by TSIG or SIG(0). The
result of <B
CLASS="command"
>TKEY</B
> is a shared secret that can be
used to sign messages with TSIG. <B
CLASS="command"
>TKEY</B
> can also
be used to delete shared secrets that it had previously
generated.</P
><P
>The <B
CLASS="command"
>TKEY</B
> process is initiated by a client
or server by sending a signed <B
CLASS="command"
>TKEY</B
> query
(including any appropriate KEYs) to a TKEY-aware server. The
server response, if it indicates success, will contain a
<B
CLASS="command"
>TKEY</B
> record and any appropriate keys. After
this exchange, both participants have enough information to
determine the shared secret; the exact process depends on the
<B
CLASS="command"
>TKEY</B
> mode. When using the Diffie-Hellman
<B
CLASS="command"
>TKEY</B
> mode, Diffie-Hellman keys are exchanged,
and the shared secret is derived by both participants.</P
></DIV
><DIV
CLASS="sect1"
><H1
CLASS="sect1"
><A
NAME="AEN942"
>4.7. SIG(0)</A
></H1
><P
><ACRONYM
CLASS="acronym"
>BIND</ACRONYM
> 9 partially supports DNSSEC SIG(0)
transaction signatures as specified in RFC 2535 and RFC2931. SIG(0)
uses public/private keys to authenticate messages. Access control
is performed in the same manner as TSIG keys; privileges can be
granted or denied based on the key name.</P
><P
>When a SIG(0) signed message is received, it will only be
verified if the key is known and trusted by the server; the server
will not attempt to locate and/or validate the key.</P
><P
>SIG(0) signing of multiple-message TCP streams is not
supported.</P
><P
>The only tool shipped with <ACRONYM
CLASS="acronym"
>BIND</ACRONYM
> 9 that
generates SIG(0) signed messages is <B
CLASS="command"
>nsupdate</B
>.</P
></DIV
><DIV
CLASS="sect1"
><H1
CLASS="sect1"
><A
NAME="DNSSEC"
>4.8. DNSSEC</A
></H1
><P
>Cryptographic authentication of DNS information is possible
through the DNS Security (<SPAN
CLASS="emphasis"
><I
CLASS="emphasis"
>DNSSEC-bis</I
></SPAN
>) extensions,
defined in RFC &#60;TBA&#62;. This section describes the creation and use
of DNSSEC signed zones.</P
><P
>In order to set up a DNSSEC secure zone, there are a series
of steps which must be followed. <ACRONYM
CLASS="acronym"
>BIND</ACRONYM
> 9 ships
with several tools
that are used in this process, which are explained in more detail
below. In all cases, the <VAR
CLASS="option"
>-h</VAR
> option prints a
full list of parameters. Note that the DNSSEC tools require the
keyset files to be in the working directory or the
directory specified by the <VAR
CLASS="option"
>-h</VAR
> option, and
that the tools shipped with BIND 9.2.x and earlier are not compatible
with the current ones.</P
><P
>There must also be communication with the administrators of
the parent and/or child zone to transmit keys. A zone's security
status must be indicated by the parent zone for a DNSSEC capable
resolver to trust its data. This is done through the presense
or absence of a <VAR
CLASS="literal"
>DS</VAR
> record at the delegation
point.</P
><P
>For other servers to trust data in this zone, they must
either be statically configured with this zone's zone key or the
zone key of another zone above this one in the DNS tree.</P
><DIV
CLASS="sect2"
><H2
CLASS="sect2"
><A
NAME="AEN962"
>4.8.1. Generating Keys</A
></H2
><P
>The <B
CLASS="command"
>dnssec-keygen</B
> program is used to
generate keys.</P
><P
>A secure zone must contain one or more zone keys. The
zone keys will sign all other records in the zone, as well as
the zone keys of any secure delegated zones. Zone keys must
have the same name as the zone, a name type of
<B
CLASS="command"
>ZONE</B
>, and must be usable for authentication.
It is recommended that zone keys use a cryptographic algorithm
designated as "mandatory to implement" by the IETF; currently
the only one is RSASHA1.</P
><P
>The following command will generate a 768 bit RSASHA1 key for
the <TT
CLASS="filename"
>child.example</TT
> zone:</P
><P
><KBD
CLASS="userinput"
>dnssec-keygen -a RSASHA1 -b 768 -n ZONE child.example.</KBD
></P
><P
>Two output files will be produced:
<TT
CLASS="filename"
>Kchild.example.+005+12345.key</TT
> and
<TT
CLASS="filename"
>Kchild.example.+005+12345.private</TT
> (where
12345 is an example of a key tag). The key file names contain
the key name (<TT
CLASS="filename"
>child.example.</TT
>), algorithm (3
is DSA, 1 is RSAMD5, 5 is RSASHA1, etc.), and the key tag (12345 in this case).
The private key (in the <TT
CLASS="filename"
>.private</TT
> file) is
used to generate signatures, and the public key (in the
<TT
CLASS="filename"
>.key</TT
> file) is used for signature
verification.</P
><P
>To generate another key with the same properties (but with
a different key tag), repeat the above command.</P
><P
>The public keys should be inserted into the zone file by
including the <TT
CLASS="filename"
>.key</TT
> files using
<B
CLASS="command"
>$INCLUDE</B
> statements.
</P
></DIV
><DIV
CLASS="sect2"
><H2
CLASS="sect2"
><A
NAME="AEN982"
>4.8.2. Signing the Zone</A
></H2
><P
>The <B
CLASS="command"
>dnssec-signzone</B
> program is used to
sign a zone.</P
><P
>Any <TT
CLASS="filename"
>keyset</TT
> files corresponding
to secure subzones should be present. The zone signer will
generate <VAR
CLASS="literal"
>NSEC</VAR
> and <VAR
CLASS="literal"
>RRSIG</VAR
>
records for the zone, as well as <VAR
CLASS="literal"
>DS</VAR
> for
the child zones if <VAR
CLASS="literal"
>'-d'</VAR
> is specified.
If <VAR
CLASS="literal"
>'-d'</VAR
> is not specified then DS RRsets for
the secure child zones need to be added manually.</P
><P
>The following command signs the zone, assuming it is in a
file called <TT
CLASS="filename"
>zone.child.example</TT
>. By
default, all zone keys which have an available private key are
used to generate signatures.</P
><P
><KBD
CLASS="userinput"
>dnssec-signzone -o child.example zone.child.example</KBD
></P
><P
>One output file is produced:
<TT
CLASS="filename"
>zone.child.example.signed</TT
>. This file
should be referenced by <TT
CLASS="filename"
>named.conf</TT
> as the
input file for the zone.</P
><P
><B
CLASS="command"
>dnssec-signzone</B
> will also produce a
keyset and dsset files and optionally a dlvset file. These
are used to provide the parent zone administators with the
<VAR
CLASS="literal"
>DNSKEYs</VAR
> (or their corresponding <VAR
CLASS="literal"
>DS</VAR
>
records) that are the secure entry point to the zone.</P
></DIV
><DIV
CLASS="sect2"
><H2
CLASS="sect2"
><A
NAME="AEN1004"
>4.8.3. Configuring Servers</A
></H2
><P
>Unlike <ACRONYM
CLASS="acronym"
>BIND</ACRONYM
> 8,
<ACRONYM
CLASS="acronym"
>BIND</ACRONYM
> 9 does not verify signatures on load,
so zone keys for authoritative zones do not need to be specified
in the configuration file.</P
><P
>The public key for any security root must be present in
the configuration file's <B
CLASS="command"
>trusted-keys</B
>
statement, as described later in this document. </P
></DIV
></DIV
><DIV
CLASS="sect1"
><H1
CLASS="sect1"
><A
NAME="AEN1011"
>4.9. IPv6 Support in <ACRONYM
CLASS="acronym"
>BIND</ACRONYM
> 9</A
></H1
><P
><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.</P
><P
>For forward lookups, <ACRONYM
CLASS="acronym"
>BIND</ACRONYM
> 9 supports only AAAA
records. The use of A6 records is deprecated by RFC 3363, and the
support for forward lookups in <ACRONYM
CLASS="acronym"
>BIND</ACRONYM
> 9 is
removed accordingly.
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
records.</P
><P
>For IPv6 reverse lookups, <ACRONYM
CLASS="acronym"
>BIND</ACRONYM
> 9 supports
the traditional "nibble" format used in the
<SPAN
CLASS="emphasis"
><I
CLASS="emphasis"
>ip6.arpa</I
></SPAN
> domain, as well as the older, deprecated
<SPAN
CLASS="emphasis"
><I
CLASS="emphasis"
>ip6.int</I
></SPAN
> domain.
<ACRONYM
CLASS="acronym"
>BIND</ACRONYM
> 9 formerly
supported the "binary label" (also known as "bitstring") format.
The support of binary labels, however, is now completely removed
according to the changes in RFC 3363.
Any applications in <ACRONYM
CLASS="acronym"
>BIND</ACRONYM
> 9 do not understand
the format any more, and will return an error if given.
In particular, an authoritative <ACRONYM
CLASS="acronym"
>BIND</ACRONYM
> 9 name
server rejects to load a zone file containing binary labels.</P
><P
>For an overview of the format and structure of IPv6 addresses,
see <A
HREF="Bv9ARM.ch09.html#ipv6addresses"
>Section A.2.1</A
>.</P
><DIV
CLASS="sect2"
><H2
CLASS="sect2"
><A
NAME="AEN1029"
>4.9.1. Address Lookups Using AAAA Records</A
></H2
><P
>The AAAA record is a parallel to the IPv4 A record. It
specifies the entire address in a single record. For
example,</P
><PRE
CLASS="programlisting"
>&#13;$ORIGIN example.com.
host 3600 IN AAAA 2001:db8::1
</PRE
><P
>It is recommended that IPv4-in-IPv6 mapped addresses not
be used. If a host has an IPv4 address, use an A record, not
a AAAA, with <VAR
CLASS="literal"
>::ffff:192.168.42.1</VAR
> as the
address.</P
></DIV
><DIV
CLASS="sect2"
><H2
CLASS="sect2"
><A
NAME="AEN1035"
>4.9.2. Address to Name Lookups Using Nibble Format</A
></H2
><P
>When looking up an address in nibble format, the address
components are simply reversed, just as in IPv4, and
<VAR
CLASS="literal"
>ip6.arpa.</VAR
> is appended to the resulting name.
For example, the following would provide reverse name lookup for
a host with address
<VAR
CLASS="literal"
>2001:db8::1</VAR
>.</P
><PRE
CLASS="programlisting"
>&#13;$ORIGIN 0.0.0.0.0.0.0.0.8.b.d.0.1.0.0.2.ip6.arpa.
1.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0 14400 IN PTR host.example.com.
</PRE
></DIV
></DIV
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