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Diffstat (limited to 'docs/docbook/projdoc/NetworkBrowsing.xml')
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1 files changed, 207 insertions, 21 deletions
diff --git a/docs/docbook/projdoc/NetworkBrowsing.xml b/docs/docbook/projdoc/NetworkBrowsing.xml index 6327bde30a..8648bfa256 100644 --- a/docs/docbook/projdoc/NetworkBrowsing.xml +++ b/docs/docbook/projdoc/NetworkBrowsing.xml @@ -23,6 +23,58 @@ The following information assumes that your site is running NetBIOS over TCP/IP. </para></note> <sect1> +<title>Features and Benefits</title> + +<para> +Someone once referred to the past in terms of: <emphasis>They were the worst of times, +they were the best of times. The more we look back, them more we long for what was and +hope it never returns!</emphasis>. +</para> + +<para> +For many MS Windows network administrators that statement sums up their feelings about +NetBIOS networking precisely. For those who mastered NetBIOS networking it's fickle +nature was just par for the course. For those who never quite managed to tame it's +lusty features NetBIOS is like Paterson's Curse. +</para> + +<para> +For those not familiar with botanical problems in Australia: Paterson's curse, +Echium plantagineum, was introduced to Australia from Europe during the mid-nineteenth +century. Since then it has spread rapidly. The high seed production, with densities of +thousands of seeds per square metre, a seed longevity of more than seven years, and an +ability to germinate at any time of year, given the right conditions, are some of the +features which make it such a persistent weed. +</para> + +<para> +In this chapter we explore vital aspects of SMB (Server Message Block) networking with +a particular focus on SMB as implmented through running NetBIOS (Network Basic +Input / Output System) over TCP/IP. Since Samba does NOT implement SMB or NetBIOS over +any other protocols we need to know how to configure our network environment and simply +remember to use nothing but TCP/IP on all our MS Windows network clients. +</para> + +<para> +Samba provides the ability to implement a WINS (Windows Internetworking Name Server) +and implements extensions to Microsoft's implementation of WINS. These extensions +help Samba to affect stable WINS operations beyond the normal scope of MS WINS. +</para> + +<para> +Please note that WINS is exclusively a service that applies only to those systems +that run NetBIOS over TCP/IP. MS Windows 200x / XP have the capacity to turn off +support for NetBIOS, in which case WINS is of no relevance. Samba-3 supports this also. +</para> + +<para> +For those networks on which NetBIOS has been disabled (ie: WINS is NOT required) +the use of DNS is necessary for host name resolution. +</para> + +</sect1> + +<sect1> <title>What is Browsing?</title> <para> @@ -76,28 +128,36 @@ called <filename>nmbd</filename>. The configuration parameters involved in nmbd' </programlisting></para> <para> -WINS Server and WINS Support are mutually exclusive options. Those marked with an '*' are -the only options that commonly MAY need to be modified. Even if not one of these parameters -is set nmbd will still do it's job. +For Samba the WINS Server and WINS Support are mutually exclusive options. Those marked with +an '*' are the only options that commonly MAY need to be modified. Even if not one of these +parameters is set nmbd will still do it's job. </para> + </sect1> <sect1> <title>Discussion</title> <para> -Firstly, all MS Windows networking is based on SMB (Server Message -Block) based messaging. SMB messaging may be implemented using NetBIOS or -without NetBIOS. Samba implements NetBIOS by encapsulating it over TCP/IP. -MS Windows products can do likewise. NetBIOS based networking uses broadcast -messaging to affect browse list management. When running NetBIOS over -TCP/IP this uses UDP based messaging. UDP messages can be broadcast or unicast. +Firstly, all MS Windows networking uses SMB (Server Message Block) based messaging. +SMB messaging may be implemented with or without NetBIOS. MS Windows 200x supports +NetBIOS over TCP/IP for backwards compatibility. Microsoft are intent on phasing out NetBIOS +support. +</para> + +<sect2> +<title>NetBIOS over TCP/IP</title> + +<para> +Samba implements NetBIOS, as does MS Windows NT / 200x / XP, by encapsulating it over TCP/IP. +MS Windows products can do likewise. NetBIOS based networking uses broadcast messaging to +affect browse list management. When running NetBIOS over TCP/IP this uses UDP based messaging. +UDP messages can be broadcast or unicast. </para> <para> Normally, only unicast UDP messaging can be forwarded by routers. The -<command>remote announce</command> -parameter to smb.conf helps to project browse announcements +<command>remote announce</command> parameter to smb.conf helps to project browse announcements to remote network segments via unicast UDP. Similarly, the <command>remote browse sync</command> parameter of <filename>smb.conf</filename> implements browse list collation using unicast UDP. @@ -121,20 +181,21 @@ the use of the <command>remote announce</command> and the <para> As of Samba 3 WINS replication is being worked on. The bulk of the code has -been committed, but it still needs maturation. +been committed, but it still needs maturation. This is NOT a supported feature +of the Samba-3.0.0 release. Hopefully, this will become a supported feature +of one of the samba-3 release series. </para> <para> Right now samba WINS does not support MS-WINS replication. This means that -when setting up Samba as a WINS server there must only be one <filename>nmbd</filename> configured -as a WINS server on the network. Some sites have used multiple Samba WINS +when setting up Samba as a WINS server there must only be one <filename>nmbd</filename> +configured as a WINS server on the network. Some sites have used multiple Samba WINS servers for redundancy (one server per subnet) and then used <command>remote browse sync</command> and <command>remote announce</command> -to affect browse list collation across all -segments. Note that this means clients will only resolve local names, -and must be configured to use DNS to resolve names on other subnets in -order to resolve the IP addresses of the servers they can see on other -subnets. This setup is not recommended, but is mentioned as a practical +to affect browse list collation across all segments. Note that this means clients +will only resolve local names, and must be configured to use DNS to resolve names +on other subnets in order to resolve the IP addresses of the servers they can see +on other subnets. This setup is not recommended, but is mentioned as a practical consideration (ie: an 'if all else fails' scenario). </para> @@ -145,15 +206,140 @@ that it will take time to establish a browse list and it can take up to 45 minutes to stabilise, particularly across network segments. </para> +</sect2> + +<sect2> +<title>TCP/IP - without NetBIOS</title> + +<para> +All TCP/IP using systems use various forms of host name resolution. The primary +methods for TCP/IP hostname resolutions involves either a static file (<filename>/etc/hosts +</filename>) or DNS (the Domain Name System). DNS is the technology that makes +the Internet usable. DNS based host name resolution is supported by nearly all TCP/IP +enabled systems. Only a few embedded TCP/IP systems do not support DNS. +</para> + +<para> +When an MS Windows 200x / XP system attempts to resolve a host name to an IP address +it follows a defined path: +</para> + +<orderedlist> + <listitem><para> + Checks the <filename>hosts</filename> file. It is located in + <filename>C:\WinNT\System32\Drivers\etc</filename>. + </para></listitem> + + <listitem><para> + Does a DNS lookup + </para></listitem> + + <listitem><para> + Checks the NetBIOS name cache + </para></listitem> + + <listitem><para> + Queries the WINS server + </para></listitem> + + <listitem><para> + Does a broadcast name lookup over UDP + </para></listitem> + + <listitem><para> + Looks up entries in LMHOSTS. It is located in + <filename>C:\WinNT\System32\Drivers\etc</filename>. + </para></listitem> +</orderedlist> + +<para> +Windows 200x / XP can register it's host name with a Dynamic DNS server. You can +force register with a Dynamic DNS server in Windows 200x / XP using: +<command>ipconfig /registerdns</command> +</para> + +<para> +With Active Directory (ADS), a correctly functioning DNS server is absolutely +essential. In the absence of a working DNS server that has been correctly configured +MS Windows clients and servers will be totally unable to locate each other, +consequently network services will be severely impaired. +</para> + +<para> +The use of Dynamic DNS is highly recommended with Active Directory, in which case +the use of BIND9 is preferred for it's ability to adequately support the SRV (service) +records that are needed for Active Directory. +</para> + +</sect2> + +<sect2> +<title>DNS and Active Directory</title> + +<para> +Occasionally we hear from Unix network administrators who want to use a Unix based Dynamic +DNS server in place of the Microsoft DNS server. While this might be desirable to some, the +MS Windows 200x DNS server is auto-configured to work with Active Directory. It is possible +to use BIND version 8 or 9, but it will almost certainly be necessary to create service records +so that MS Active Directory clients can resolve host names to locate essential network services. +The following are some of the default service records that Active Directory requires: +</para> + +<itemizedlist> + <listitem><para>_ldap._tcp.pdc.ms-dcs.<emphasis>Domain</emphasis></para> + + <para> + This provides the address of the Windows NT PDC for the Domain. + </para> + </listitem> + + <listitem><para>_ldap._tcp.pdc.ms-dcs.<emphasis>DomainTree</emphasis></para> + + <para> + Resolves the addresses of Global Catalog servers in the domain. + </para> + </listitem> + + <listitem><para>_ldap._tcp.<emphasis>site</emphasis>.sites.writable.ms-dcs.<emphasis>Domain</emphasis></para> + <para> + Provides list of domain controllers based on sites. + </para> + </listitem> + + <listitem><para>_ldap._tcp.writable.ms-dcs.<emphasis>Domain</emphasis></para> + + <para> + Enumerates list of domain controllers that have the writable + copies of the Active Directory data store. + </para> + </listitem> + + <listitem><para>_ldap._tcp.<emphasis>GUID</emphasis>.domains.ms-dcs.<emphasis>DomainTree</emphasis></para> + <para> + Entry used by MS Windows clients to locate machines using the + Global Unique Identifier. + </para> + </listitem> + + <listitem><para>_ldap._tcp.<emphasis>Site</emphasis>.gc.ms-dcs.<emphasis>DomainTree</emphasis></para> + <para> + Used by MS Windows clients to locate site configuration dependant + Global Catalog server. + </para> + </listitem> +</itemizedlist> + +</sect2> + </sect1> <sect1> <title>How Browsing Functions</title> <para> -As stated above, MS Windows machines register their NetBIOS names +MS Windows machines register their NetBIOS names (ie: the machine name for each service type in operation) on start -up. Also, as stated above, the exact method by which this name registration +up. The exact method by which this name registration takes place is determined by whether or not the MS Windows client/server has been given a WINS server address, whether or not LMHOSTS lookup is enabled, or if DNS for NetBIOS name resolution is enabled, etc. |