| 1 | <?xml version="1.0" encoding="iso-8859-1"?>
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| 2 | <!DOCTYPE chapter PUBLIC "-//Samba-Team//DTD DocBook V4.2-Based Variant V1.0//EN" "http://www.samba.org/samba/DTD/samba-doc">
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| 3 | <chapter id="wins">
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| 4 | <chapterinfo>
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| 5 | <author>
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| 6 | <firstname>Gerald</firstname><surname>Carter</surname>
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| 7 | </author>
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| 8 | <pubdate>October 2002</pubdate>
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| 9 | </chapterinfo>
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| 10 |
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| 11 |
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| 12 | <title>Samba WINS Internals</title>
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| 13 |
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| 14 |
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| 15 | <sect1>
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| 16 | <title>WINS Failover</title>
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| 17 |
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| 18 |
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| 19 | <para>
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| 20 | The current Samba codebase possesses the capability to use groups of WINS
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| 21 | servers that share a common namespace for NetBIOS name registration and
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| 22 | resolution. The formal parameter syntax is
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| 23 | </para>
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| 24 |
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| 25 | <para><programlisting>
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| 26 | WINS_SERVER_PARAM = SERVER [ SEPARATOR SERVER_LIST ]
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| 27 | WINS_SERVER_PARAM = "wins server"
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| 28 | SERVER = ADDR[:TAG]
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| 29 | ADDR = ip_addr | fqdn
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| 30 | TAG = string
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| 31 | SEPARATOR = comma | \s+
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| 32 | SERVER_LIST = SERVER [ SEPARATOR SERVER_LIST ]
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| 33 | </programlisting></para>
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| 34 |
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| 35 | <para>
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| 36 | A simple example of a valid wins server setting is
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| 37 | </para>
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| 38 |
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| 39 | <para><programlisting>
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| 40 | [global]
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| 41 | wins server = 192.168.1.2 192.168.1.3
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| 42 | </programlisting></para>
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| 43 |
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| 44 | <para>
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| 45 | In the event that no TAG is defined in for a SERVER in the list, smbd assigns a default
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| 46 | TAG of "*". A TAG is used to group servers of a shared NetBIOS namespace together. Upon
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| 47 | startup, nmbd will attempt to register the netbios name value with one server in each
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| 48 | tagged group.
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| 49 | </para>
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| 50 |
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| 51 | <para>
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| 52 | An example using tags to group WINS servers together is show here. Note that the use of
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| 53 | interface names in the tags is only by convention and is not a technical requirement.
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| 54 | </para>
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| 55 |
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| 56 |
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| 57 | <para><programlisting>
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| 58 | [global]
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| 59 | wins server = 192.168.1.2:eth0 192.168.1.3:eth0 192.168.2.2:eth1
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| 60 | </programlisting></para>
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| 61 |
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| 62 | <para>
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| 63 | Using this configuration, nmbd would attempt to register the server's NetBIOS name
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| 64 | with one WINS server in each group. Because the "eth0" group has two servers, the
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| 65 | second server would only be used when a registration (or resolution) request to
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| 66 | the first server in that group timed out.
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| 67 | </para>
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| 68 |
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| 69 | <para>
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| 70 | NetBIOS name resolution follows a similar pattern as name registration. When resolving
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| 71 | a NetBIOS name via WINS, smbd and other Samba programs will attempt to query a single WINS
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| 72 | server in a tagged group until either a positive response is obtained at least once or
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| 73 | until a server from every tagged group has responded negatively to the name query request.
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| 74 | If a timeout occurs when querying a specific WINS server, that server is marked as down to
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| 75 | prevent further timeouts and the next server in the WINS group is contacted. Once marked as
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| 76 | dead, Samba will not attempt to contact that server for name registration/resolution queries
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| 77 | for a period of 10 minutes.
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| 78 | </para>
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| 79 |
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| 80 | </sect1>
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| 81 | </chapter>
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