122 lines
6.7 KiB
HTML
122 lines
6.7 KiB
HTML
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<?xml version="1.0" encoding="UTF-8"?>
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<!DOCTYPE html
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PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
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<html lang="en-us" xml:lang="en-us">
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<meta name="DC.Type" content="task" />
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<meta name="DC.Title" content="Define realms in the DNS database" />
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<meta name="abstract" content="Define realms in the DNS database to resolve host names." />
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<meta name="description" content="Define realms in the DNS database to resolve host names." />
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<meta name="DC.Relation" scheme="URI" content="rzakhmanage.htm" />
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<meta name="copyright" content="(C) Copyright IBM Corporation 1998, 2006" />
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<meta name="DC.Identifier" content="definerealmsdns" />
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<!-- All rights reserved. Licensed Materials Property of IBM -->
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<link rel="stylesheet" type="text/css" href="./ibmdita.css" />
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<link rel="stylesheet" type="text/css" href="./ic.css" />
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<title>Define realms in the DNS database</title>
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</head>
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<body id="definerealmsdns"><a name="definerealmsdns"><!-- --></a>
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<!-- Java sync-link --><script language="Javascript" src="../rzahg/synch.js" type="text/javascript"></script>
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<h1 class="topictitle1">Define realms in the DNS database</h1>
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<div><p>Define realms in the DNS database to resolve host names.</p>
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<div class="section"><p>Network authentication service allows you to use the DNS server
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to resolve host names. To do this, you need to add a server (SRV) record and
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text (TXT) record for each key distribution center in the realm. The Kerberos
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protocol searches for an SRV record using the realm name as the DNS search
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name. </p>
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<p>To define realms with DNS, complete the following steps: </p>
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</div>
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<ol><li class="stepexpand"><span><a href="rzakhhost.htm#rzakhhost">Set the configuration file
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to use DNS</a>.</span></li>
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<li class="stepexpand"><span>Add SRV records to your DNS server for each KDC server in the realm. </span> The Kerberos run time searches for an SRV record by using the realm
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name as the search name. Note that DNS searches are not case-sensitive, so
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you cannot have two different realms whose names differ only in their case. The general form of the Kerberos SRV record is as follows:<pre>service.protocol.realm TTL class SRV priority weight port target</pre>
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<p>The _kerberos service entries define KDC instances, and
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_kpasswd service entries define password change service instances.</p>
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<p>Entries
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are tried in priority order (0 is the highest priority). Entries with the
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same priority are tried in random order. The _udp protocol records are required
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for _kerberos and _kpasswd entries.</p>
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</li>
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<li class="stepexpand"><span>Add TXT records to associate host names with realm names. </span> The Kerberos protocol searches for a TXT record starting with the host
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name. If no TXT record is found, the first label is removed and the search
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is retried with the new name. This process continues until a TXT record is
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found or the root is reached. Note that the realm name is case-sensitive in
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the TXT record. The general format of a TXT record is as follows:<pre>service.name TTL class TXT realm</pre>
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<p>For
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our configuration example, you can define the example KDCs for the two realms
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by adding the following records: </p>
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<div class="p"><p><tt>_kerberos._udp.deptxyz.bogusname.com IN SRV 0 0 88 kdc1.deptxyz.bogusname.com<br />
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_kerberos._tcp.deptxyz.bogusname.com IN SRV 0 0 88 kdc1.deptxyz.bogusname.com<br />
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_kerberos._udp.deptabc.bogusname.com IN SRV 0 0 88 kdc2.deptabc.bogusname.com<br />
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_kerberos._tcp.deptabc.bogusname.com IN SRV 0 0 88 kdc2.deptabc.bogusname.com<br />
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_kpasswd._udp.deptxyz.bogusname.com IN SRV 0 0 464 kdc1.deptxyz.bogusname.com<br />
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_kpasswd._tcp.deptxyz.bogusname.com IN SRV 0 0 464 kdc1.deptxyz.bogusname.com<br />
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_kpasswd._udp.deptabc.bogusname.com IN SRV 0 0 464 kdc2.deptxyz.bogusname.com<br />
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_kpasswd._tcp.deptabc.bogusname.com IN SRV 0 0 464 kdc2.deptxyz.bogusname.com</tt></p>
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</div>
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<p>For
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our configuration example, following the general form of a Kerberos TXT record,
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we can associate hosts in the deptxyz and deptabc domains to their respective
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realms with the following statements: </p>
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<div class="p"><p>_kerberos.deptxyz.bogusname.com IN TXT DEPTXYZ.BOGUSNAME.COM<br />
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_kerberos.deptabc.bogusname.com IN TXT DEPTABC.BOGUSNAME.COM</p>
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</div>
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<p>Following
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is a sample <strong>krb5.conf</strong> configuration file that specifies using DNS lookup:</p>
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<p><strong>Sample
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krb5.conf configuration file</strong></p>
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<div class="p"> <pre>; krb5.conf - Kerberos V5 configuration file DO NOT REMOVE THIS LINE
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;</pre>
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<pre>[libdefaults]</pre>
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<pre>; The default_realm value
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;-default_realm = REALM1.ROCHESTER.IBM.COM
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default_realm = DEPTXYZ.BOGUSNAME.COM</pre>
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<pre>; define the system to use DNS lookup
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use_dns_lookup = 1</pre>
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<pre>[realms]
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;
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; We could configure the same realm information here, but it would
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; only be used if the DNS lookup failed.
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;</pre>
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<pre>[domain_realm]
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; Convert host names to realm names. Individual host names may be
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; specified. Domain suffixes may be specified with a leading period
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; and will apply to all host names ending in that suffix.
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;
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; We will use DNS to resolve what realm a given host name belongs to.
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;</pre>
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<pre>[capaths]
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; Configurable authentication paths define the trust relationships
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; between client and servers. Each entry represents a client realm
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; and consists of the trust relationships for each server that can
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; be accessed from that realm. A server may be listed multiple times
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; if multiple trust relationships are involved. Specify '.' for
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; a direct connection.
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;-REALM1.ROCHESTER.IBM.COM = {
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;- REALM2.ROCHESTER.IBM.COM = .
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;;}
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DEPTXYZ.BOGUSNAME.COM = {
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DEPTABC.BOGUSNAME.COM = .
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}</pre>
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</div>
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</li>
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</ol>
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</div>
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<div>
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<div class="familylinks">
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<div class="parentlink"><strong>Parent topic:</strong> <a href="rzakhmanage.htm" title="Manage network authentication service by requesting tickets, working with key table files, and administering host name resolution. You can also work with credentials files and back up configuration files.">Manage network authentication service</a></div>
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</div>
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</div>
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</body>
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</html>
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