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| author | Gerald Carter <jerry@samba.org> | 2003-07-16 05:42:34 +0000 |
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| committer | Gerald Carter <jerry@samba.org> | 2003-07-16 05:42:34 +0000 |
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diff --git a/docs/htmldocs/NetworkBrowsing.html b/docs/htmldocs/NetworkBrowsing.html new file mode 100644 index 0000000000..eb4d9858ca --- /dev/null +++ b/docs/htmldocs/NetworkBrowsing.html @@ -0,0 +1,957 @@ +<html><head><meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"><title>Chapter 10. Samba / MS Windows Network Browsing Guide</title><link rel="stylesheet" href="samba.css" type="text/css"><meta name="generator" content="DocBook XSL Stylesheets V1.60.1"><link rel="home" href="index.html" title="SAMBA Project Documentation"><link rel="up" href="optional.html" title="Part III. Advanced Configuration"><link rel="previous" href="optional.html" title="Part III. Advanced Configuration"><link rel="next" href="passdb.html" title="Chapter 11. Account Information Databases"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">Chapter 10. Samba / MS Windows Network Browsing Guide</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="optional.html">Prev</a> </td><th width="60%" align="center">Part III. Advanced Configuration</th><td width="20%" align="right"> <a accesskey="n" href="passdb.html">Next</a></td></tr></table><hr></div><div class="chapter" lang="en"><div class="titlepage"><div><div><h2 class="title"><a name="NetworkBrowsing"></a>Chapter 10. Samba / MS Windows Network Browsing Guide</h2></div><div><div class="author"><h3 class="author"><span class="firstname">John</span> <span class="othername">H.</span> <span class="surname">Terpstra</span></h3><div class="affiliation"><span class="orgname">Samba Team<br></span><div class="address"><p><tt class="email"><<a href="mailto:jht@samba.org">jht@samba.org</a>></tt></p></div></div></div></div><div><p class="pubdate">July 5, 1998</p></div><div><p class="pubdate">Updated: April 21, 2003</p></div></div><div></div></div><div class="toc"><p><b>Table of Contents</b></p><dl><dt><a href="NetworkBrowsing.html#id2903558">Features and Benefits</a></dt><dt><a href="NetworkBrowsing.html#id2903637">What is Browsing?</a></dt><dt><a href="NetworkBrowsing.html#id2903747">Discussion</a></dt><dd><dl><dt><a href="NetworkBrowsing.html#id2903764">NetBIOS over TCP/IP</a></dt><dt><a href="NetworkBrowsing.html#id2903926">TCP/IP - without NetBIOS</a></dt><dt><a href="NetworkBrowsing.html#id2904058">DNS and Active Directory</a></dt></dl></dd><dt><a href="NetworkBrowsing.html#id2904194">How Browsing Functions</a></dt><dd><dl><dt><a href="NetworkBrowsing.html#id2904320">Setting up WORKGROUP Browsing</a></dt><dt><a href="NetworkBrowsing.html#id2904541">Setting up DOMAIN Browsing</a></dt><dt><a href="NetworkBrowsing.html#browse-force-master">Forcing Samba to be the master</a></dt><dt><a href="NetworkBrowsing.html#id2904811">Making Samba the domain master</a></dt><dt><a href="NetworkBrowsing.html#id2904967">Note about broadcast addresses</a></dt><dt><a href="NetworkBrowsing.html#id2904984">Multiple interfaces</a></dt><dt><a href="NetworkBrowsing.html#id2905013">Use of the Remote Announce parameter</a></dt><dt><a href="NetworkBrowsing.html#id2905122">Use of the Remote Browse Sync parameter</a></dt></dl></dd><dt><a href="NetworkBrowsing.html#id2905183">WINS - The Windows Internetworking Name Server</a></dt><dd><dl><dt><a href="NetworkBrowsing.html#id2905341">Setting up a WINS server</a></dt><dt><a href="NetworkBrowsing.html#id2905540">WINS Replication</a></dt><dt><a href="NetworkBrowsing.html#id2905565">Static WINS Entries</a></dt></dl></dd><dt><a href="NetworkBrowsing.html#id2905650">Helpful Hints</a></dt><dd><dl><dt><a href="NetworkBrowsing.html#id2905663">Windows Networking Protocols</a></dt><dt><a href="NetworkBrowsing.html#id2905730">Name Resolution Order</a></dt></dl></dd><dt><a href="NetworkBrowsing.html#id2905867">Technical Overview of browsing</a></dt><dd><dl><dt><a href="NetworkBrowsing.html#id2905914">Browsing support in Samba</a></dt><dt><a href="NetworkBrowsing.html#id2906021">Problem resolution</a></dt><dt><a href="NetworkBrowsing.html#id2906100">Browsing across subnets</a></dt></dl></dd><dt><a href="NetworkBrowsing.html#id2906720">Common Errors</a></dt><dd><dl><dt><a href="NetworkBrowsing.html#id2906735">How can one flush the Samba NetBIOS name cache without restarting Samba?</a></dt><dt><a href="NetworkBrowsing.html#id2906764">My client reports "This server is not configured to list shared resources"</a></dt></dl></dd></dl></div><p> +This document contains detailed information as well as a fast track guide to +implementing browsing across subnets and / or across workgroups (or domains). +WINS is the best tool for resolution of NetBIOS names to IP addresses. WINS is +NOT involved in browse list handling except by way of name to address resolution. +</p><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p> +MS Windows 2000 and later can be configured to operate with NO NetBIOS +over TCP/IP. Samba-3 and later also supports this mode of operation. +When the use of NetBIOS over TCP/IP has been disabled then the primary +means for resolution of MS Windows machine names is via DNS and Active Directory. +The following information assumes that your site is running NetBIOS over TCP/IP. +</p></div><div class="sect1" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2903558"></a>Features and Benefits</h2></div></div><div></div></div><p> +Someone once referred to the past in terms of: <span class="emphasis"><em>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!</em></span>. +</p><p> +For many MS Windows network administrators, that statement sums up their feelings about +NetBIOS networking precisely. For those who mastered NetBIOS networking, its fickle +nature was just par for the course. For those who never quite managed to tame its +lusty features, NetBIOS is like Paterson's Curse. +</p><p> +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. +</p><p> +In this chapter we explore vital aspects of SMB (Server Message Block) networking with +a particular focus on SMB as implemented 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. +</p><p> +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. +</p><p> +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. +</p><p> +For those networks on which NetBIOS has been disabled (ie: WINS is NOT required) +the use of DNS is necessary for host name resolution. +</p></div><div class="sect1" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2903637"></a>What is Browsing?</h2></div></div><div></div></div><p> +To most people browsing means that they can see the MS Windows and Samba servers +in the Network Neighborhood, and when the computer icon for a particular server is +clicked, it opens up and shows the shares and printers available on the target server. +</p><p> +What seems so simple is in fact a very complex interaction of different technologies. +The technologies (or methods) employed in making all of this work includes: +</p><table class="simplelist" border="0" summary="Simple list"><tr><td>MS Windows machines register their presence to the network</td></tr><tr><td>Machines announce themselves to other machines on the network</td></tr><tr><td>One or more machine on the network collates the local announcements</td></tr><tr><td>The client machine finds the machine that has the collated list of machines</td></tr><tr><td>The client machine is able to resolve the machine names to IP addresses</td></tr><tr><td>The client machine is able to connect to a target machine</td></tr></table><p> +The Samba application that controls browse list management and name resolution is +called <tt class="filename">nmbd</tt>. The configuration parameters involved in nmbd's operation are: +</p><pre class="programlisting"> + + Browsing options: + ----------------- + * os level + lm announce + lm interval + * preferred master + * local master + * domain master + browse list + enhanced browsing + + Name Resolution Method: + ----------------------- + * name resolve order + + WINS options: + ------------- + dns proxy + wins proxy + * wins server + * wins support + wins hook +</pre><p> +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 <tt class="filename">nmbd</tt> will still do it's job. +</p></div><div class="sect1" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2903747"></a>Discussion</h2></div></div><div></div></div><p> +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 is intent on phasing out NetBIOS +support. +</p><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2903764"></a>NetBIOS over TCP/IP</h3></div></div><div></div></div><p> +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. +</p><p> +Normally, only unicast UDP messaging can be forwarded by routers. The +<b class="command">remote announce</b> parameter to smb.conf helps to project browse announcements +to remote network segments via unicast UDP. Similarly, the +<b class="command">remote browse sync</b> parameter of <tt class="filename">smb.conf</tt> +implements browse list collation using unicast UDP. +</p><p> +Secondly, in those networks where Samba is the only SMB server technology, +wherever possible <tt class="filename">nmbd</tt> should be configured on one (1) machine as the WINS +server. This makes it easy to manage the browsing environment. If each network +segment is configured with it's own Samba WINS server, then the only way to +get cross segment browsing to work is by using the +<b class="command">remote announce</b> and the <b class="command">remote browse sync</b> +parameters to your <tt class="filename">smb.conf</tt> file. +</p><p> +If only one WINS server is used for an entire multi-segment network then +the use of the <b class="command">remote announce</b> and the +<b class="command">remote browse sync</b> parameters should NOT be necessary. +</p><p> +As of Samba 3 WINS replication is being worked on. The bulk of the code has +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. +</p><p> +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 <tt class="filename">nmbd</tt> +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 +<b class="command">remote browse sync</b> and <b class="command">remote announce</b> +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). +</p><p> +Lastly, take note that browse lists are a collection of unreliable broadcast +messages that are repeated at intervals of not more than 15 minutes. This means +that it will take time to establish a browse list and it can take up to 45 +minutes to stabilise, particularly across network segments. +</p></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2903926"></a>TCP/IP - without NetBIOS</h3></div></div><div></div></div><p> +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 (<tt class="filename">/etc/hosts +</tt>) 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. +</p><p> +When an MS Windows 200x / XP system attempts to resolve a host name to an IP address +it follows a defined path: +</p><div class="orderedlist"><ol type="1"><li><p> + Checks the <tt class="filename">hosts</tt> file. It is located in + <tt class="filename">C:\WinNT\System32\Drivers\etc</tt>. + </p></li><li><p> + Does a DNS lookup + </p></li><li><p> + Checks the NetBIOS name cache + </p></li><li><p> + Queries the WINS server + </p></li><li><p> + Does a broadcast name lookup over UDP + </p></li><li><p> + Looks up entries in LMHOSTS. It is located in + <tt class="filename">C:\WinNT\System32\Drivers\etc</tt>. + </p></li></ol></div><p> +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: +<b class="command">ipconfig /registerdns</b> +</p><p> +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. +</p><p> +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. +</p></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2904058"></a>DNS and Active Directory</h3></div></div><div></div></div><p> +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: +</p><div class="itemizedlist"><ul type="disc"><li><p>_ldap._tcp.pdc.ms-dcs.<span class="emphasis"><em>Domain</em></span></p><p> + This provides the address of the Windows NT PDC for the Domain. + </p></li><li><p>_ldap._tcp.pdc.ms-dcs.<span class="emphasis"><em>DomainTree</em></span></p><p> + Resolves the addresses of Global Catalog servers in the domain. + </p></li><li><p>_ldap._tcp.<span class="emphasis"><em>site</em></span>.sites.writable.ms-dcs.<span class="emphasis"><em>Domain</em></span></p><p> + Provides list of domain controllers based on sites. + </p></li><li><p>_ldap._tcp.writable.ms-dcs.<span class="emphasis"><em>Domain</em></span></p><p> + Enumerates list of domain controllers that have the writable + copies of the Active Directory data store. + </p></li><li><p>_ldap._tcp.<span class="emphasis"><em>GUID</em></span>.domains.ms-dcs.<span class="emphasis"><em>DomainTree</em></span></p><p> + Entry used by MS Windows clients to locate machines using the + Global Unique Identifier. + </p></li><li><p>_ldap._tcp.<span class="emphasis"><em>Site</em></span>.gc.ms-dcs.<span class="emphasis"><em>DomainTree</em></span></p><p> + Used by MS Windows clients to locate site configuration dependent + Global Catalog server. + </p></li></ul></div></div></div><div class="sect1" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2904194"></a>How Browsing Functions</h2></div></div><div></div></div><p> +MS Windows machines register their NetBIOS names +(ie: the machine name for each service type in operation) on start +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. +</p><p> +In the case where there is no WINS server, all name registrations as +well as name lookups are done by UDP broadcast. This isolates name +resolution to the local subnet, unless LMHOSTS is used to list all +names and IP addresses. In such situations Samba provides a means by +which the Samba server name may be forcibly injected into the browse +list of a remote MS Windows network (using the +<b class="command">remote announce</b> parameter). +</p><p> +Where a WINS server is used, the MS Windows client will use UDP +unicast to register with the WINS server. Such packets can be routed +and thus WINS allows name resolution to function across routed networks. +</p><p> +During the startup process an election will take place to create a +local master browser if one does not already exist. On each NetBIOS network +one machine will be elected to function as the domain master browser. This +domain browsing has nothing to do with MS security domain control. +Instead, the domain master browser serves the role of contacting each local +master browser (found by asking WINS or from LMHOSTS) and exchanging browse +list contents. This way every master browser will eventually obtain a complete +list of all machines that are on the network. Every 11-15 minutes an election +is held to determine which machine will be the master browser. By the nature of +the election criteria used, the machine with the highest uptime, or the +most senior protocol version, or other criteria, will win the election +as domain master browser. +</p><p> +Clients wishing to browse the network make use of this list, but also depend +on the availability of correct name resolution to the respective IP +address/addresses. +</p><p> +Any configuration that breaks name resolution and/or browsing intrinsics +will annoy users because they will have to put up with protracted +inability to use the network services. +</p><p> +Samba supports a feature that allows forced synchronisation +of browse lists across routed networks using the <b class="command">remote +browse sync</b> parameter in the <tt class="filename">smb.conf</tt> file. +This causes Samba to contact the local master browser on a remote network and +to request browse list synchronisation. This effectively bridges +two networks that are separated by routers. The two remote +networks may use either broadcast based name resolution or WINS +based name resolution, but it should be noted that the <b class="command">remote +browse sync</b> parameter provides browse list synchronisation - and +that is distinct from name to address resolution, in other +words, for cross subnet browsing to function correctly it is +essential that a name to address resolution mechanism be provided. +This mechanism could be via DNS, <tt class="filename">/etc/hosts</tt>, +and so on. +</p><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2904320"></a>Setting up WORKGROUP Browsing</h3></div></div><div></div></div><p> +To set up cross subnet browsing on a network containing machines +in up to be in a WORKGROUP, not an NT Domain you need to set up one +Samba server to be the Domain Master Browser (note that this is *NOT* +the same as a Primary Domain Controller, although in an NT Domain the +same machine plays both roles). The role of a Domain master browser is +to collate the browse lists from local master browsers on all the +subnets that have a machine participating in the workgroup. Without +one machine configured as a domain master browser each subnet would +be an isolated workgroup, unable to see any machines on any other +subnet. It is the presence of a domain master browser that makes +cross subnet browsing possible for a workgroup. +</p><p> +In an WORKGROUP environment the domain master browser must be a +Samba server, and there must only be one domain master browser per +workgroup name. To set up a Samba server as a domain master browser, +set the following option in the <i class="parameter"><tt>[global]</tt></i> section +of the <tt class="filename">smb.conf</tt> file : +</p><p> +</p><pre class="programlisting"> + domain master = yes +</pre><p> +</p><p> +The domain master browser should also preferrably be the local master +browser for its own subnet. In order to achieve this set the following +options in the <i class="parameter"><tt>[global]</tt></i> section of the <tt class="filename">smb.conf</tt> file : +</p><p> +</p><pre class="programlisting"> + domain master = yes + local master = yes + preferred master = yes + os level = 65 +</pre><p> +</p><p> +The domain master browser may be the same machine as the WINS +server, if you require. +</p><p> +Next, you should ensure that each of the subnets contains a +machine that can act as a local master browser for the +workgroup. Any MS Windows NT/2K/XP/2003 machine should be +able to do this, as will Windows 9x machines (although these +tend to get rebooted more often, so it's not such a good idea +to use these). To make a Samba server a local master browser +set the following options in the <i class="parameter"><tt>[global]</tt></i> section of the +<tt class="filename">smb.conf</tt> file : +</p><p> +</p><pre class="programlisting"> + domain master = no + local master = yes + preferred master = yes + os level = 65 +</pre><p> +</p><p> +Do not do this for more than one Samba server on each subnet, +or they will war with each other over which is to be the local +master browser. +</p><p> +The <i class="parameter"><tt>local master</tt></i> parameter allows Samba to act as a +local master browser. The <i class="parameter"><tt>preferred master</tt></i> causes nmbd +to force a browser election on startup and the <i class="parameter"><tt>os level</tt></i> +parameter sets Samba high enough so that it should win any browser elections. +</p><p> +If you have an NT machine on the subnet that you wish to +be the local master browser then you can disable Samba from +becoming a local master browser by setting the following +options in the <i class="parameter"><tt>[global]</tt></i> section of the +<tt class="filename">smb.conf</tt> file : +</p><p> +</p><pre class="programlisting"> + domain master = no + local master = no + preferred master = no + os level = 0 +</pre><p> +</p></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2904541"></a>Setting up DOMAIN Browsing</h3></div></div><div></div></div><p> +If you are adding Samba servers to a Windows NT Domain then +you must not set up a Samba server as a domain master browser. +By default, a Windows NT Primary Domain Controller for a domain +is also the Domain master browser for that domain, and many +things will break if a Samba server registers the Domain master +browser NetBIOS name (<i class="replaceable"><tt>DOMAIN</tt></i><1B>) +with WINS instead of the PDC. +</p><p> +For subnets other than the one containing the Windows NT PDC +you may set up Samba servers as local master browsers as +described. To make a Samba server a local master browser set +the following options in the <b class="command">[global]</b> section +of the <tt class="filename">smb.conf</tt> file : +</p><p> +</p><pre class="programlisting"> + domain master = no + local master = yes + preferred master = yes + os level = 65 +</pre><p> +</p><p> +If you wish to have a Samba server fight the election with machines +on the same subnet you may set the <i class="parameter"><tt>os level</tt></i> parameter +to lower levels. By doing this you can tune the order of machines that +will become local master browsers if they are running. For +more details on this see the section <a href="NetworkBrowsing.html#browse-force-master" title="Forcing Samba to be the master"> +Forcing Samba to be the master browser</a> +below. +</p><p> +If you have Windows NT machines that are members of the domain +on all subnets, and you are sure they will always be running then +you can disable Samba from taking part in browser elections and +ever becoming a local master browser by setting following options +in the <i class="parameter"><tt>[global]</tt></i> section of the <tt class="filename">smb.conf</tt> +file : +</p><p> +</p><pre class="programlisting"> + domain master = no + local master = no + preferred master = no + os level = 0 +</pre><p> +</p></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="browse-force-master"></a>Forcing Samba to be the master</h3></div></div><div></div></div><p> +Who becomes the <i class="parameter"><tt>master browser</tt></i> is determined by an election +process using broadcasts. Each election packet contains a number of parameters +which determine what precedence (bias) a host should have in the +election. By default Samba uses a very low precedence and thus loses +elections to just about anyone else. +</p><p> +If you want Samba to win elections then just set the <i class="parameter"><tt>os level</tt></i> global +option in <tt class="filename">smb.conf</tt> to a higher number. It defaults to 0. Using 34 +would make it win all elections over every other system (except other +samba systems!) +</p><p> +A <i class="parameter"><tt>os level</tt></i> of 2 would make it beat WfWg and Win95, but not MS Windows +NT/2K Server. A MS Windows NT/2K Server domain controller uses level 32. +</p><p>The maximum os level is 255</p><p> +If you want Samba to force an election on startup, then set the +<i class="parameter"><tt>preferred master</tt></i> global option in <tt class="filename">smb.conf</tt> to <tt class="constant">yes</tt>. Samba will +then have a slight advantage over other potential master browsers +that are not preferred master browsers. Use this parameter with +care, as if you have two hosts (whether they are Windows 95 or NT or +Samba) on the same local subnet both set with <i class="parameter"><tt>preferred master</tt></i> to +<tt class="constant">yes</tt>, then periodically and continually they will force an election +in order to become the local master browser. +</p><p> +If you want Samba to be a <i class="parameter"><tt>domain master browser</tt></i>, then it is +recommended that you also set <i class="parameter"><tt>preferred master</tt></i> to <tt class="constant">yes</tt>, because +Samba will not become a domain master browser for the whole of your +LAN or WAN if it is not also a local master browser on its own +broadcast isolated subnet. +</p><p> +It is possible to configure two Samba servers to attempt to become +the domain master browser for a domain. The first server that comes +up will be the domain master browser. All other Samba servers will +attempt to become the domain master browser every 5 minutes. They +will find that another Samba server is already the domain master +browser and will fail. This provides automatic redundancy, should +the current domain master browser fail. +</p></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2904811"></a>Making Samba the domain master</h3></div></div><div></div></div><p> +The domain master is responsible for collating the browse lists of +multiple subnets so that browsing can occur between subnets. You can +make Samba act as the domain master by setting <i class="parameter"><tt>domain master = yes</tt></i> +in <tt class="filename">smb.conf</tt>. By default it will not be a domain master. +</p><p> +Note that you should <span class="emphasis"><em>not</em></span> set Samba to be the domain master for a +workgroup that has the same name as an NT Domain. +</p><p> +When Samba is the domain master and the master browser, it will listen +for master announcements (made roughly every twelve minutes) from local +master browsers on other subnets and then contact them to synchronise +browse lists. +</p><p> +If you want Samba to be the domain master then I suggest you also set +the <i class="parameter"><tt>os level</tt></i> high enough to make sure it wins elections, and set +<i class="parameter"><tt>preferred master</tt></i> to <tt class="constant">yes</tt>, to get Samba to force an election on +startup. +</p><p> +Note that all your servers (including Samba) and clients should be +using a WINS server to resolve NetBIOS names. If your clients are only +using broadcasting to resolve NetBIOS names, then two things will occur: +</p><div class="orderedlist"><ol type="1"><li><p> + your local master browsers will be unable to find a domain master + browser, as it will only be looking on the local subnet. + </p></li><li><p> + if a client happens to get hold of a domain-wide browse list, and + a user attempts to access a host in that list, it will be unable to + resolve the NetBIOS name of that host. + </p></li></ol></div><p> +If, however, both Samba and your clients are using a WINS server, then: +</p><div class="orderedlist"><ol type="1"><li><p> + your local master browsers will contact the WINS server and, as long as + Samba has registered that it is a domain master browser with the WINS + server, your local master browser will receive Samba's IP address + as its domain master browser. + </p></li><li><p> + when a client receives a domain-wide browse list, and a user attempts + to access a host in that list, it will contact the WINS server to + resolve the NetBIOS name of that host. as long as that host has + registered its NetBIOS name with the same WINS server, the user will + be able to see that host. + </p></li></ol></div></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2904967"></a>Note about broadcast addresses</h3></div></div><div></div></div><p> +If your network uses a "0" based broadcast address (for example if it +ends in a 0) then you will strike problems. Windows for Workgroups +does not seem to support a 0's broadcast and you will probably find +that browsing and name lookups won't work. +</p></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2904984"></a>Multiple interfaces</h3></div></div><div></div></div><p> +Samba now supports machines with multiple network interfaces. If you +have multiple interfaces then you will need to use the <b class="command">interfaces</b> +option in <tt class="filename">smb.conf</tt> to configure them. +</p></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2905013"></a>Use of the Remote Announce parameter</h3></div></div><div></div></div><p> +The <i class="parameter"><tt>remote announce</tt></i> parameter of +<tt class="filename">smb.conf</tt> can be used to forcibly ensure +that all the NetBIOS names on a network get announced to a remote network. +The syntax of the <i class="parameter"><tt>remote announce</tt></i> parameter is: +</p><pre class="programlisting"> + remote announce = a.b.c.d [e.f.g.h] ... +</pre><p> +<span class="emphasis"><em>or</em></span> +</p><pre class="programlisting"> + remote announce = a.b.c.d/WORKGROUP [e.f.g.h/WORKGROUP] ... +</pre><p> + +where: +</p><div class="variablelist"><dl><dt><span class="term"><i class="replaceable"><tt>a.b.c.d</tt></i> and +<i class="replaceable"><tt>e.f.g.h</tt></i></span></dt><dd><p>is either the LMB (Local Master Browser) IP address +or the broadcast address of the remote network. +ie: the LMB is at 192.168.1.10, or the address +could be given as 192.168.1.255 where the netmask +is assumed to be 24 bits (255.255.255.0). +When the remote announcement is made to the broadcast +address of the remote network, every host will receive +our announcements. This is noisy and therefore +undesirable but may be necessary if we do NOT know +the IP address of the remote LMB.</p></dd><dt><span class="term"><i class="replaceable"><tt>WORKGROUP</tt></i></span></dt><dd><p>is optional and can be either our own workgroup +or that of the remote network. If you use the +workgroup name of the remote network then our +NetBIOS machine names will end up looking like +they belong to that workgroup, this may cause +name resolution problems and should be avoided. +</p></dd></dl></div><p> +</p></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2905122"></a>Use of the Remote Browse Sync parameter</h3></div></div><div></div></div><p> +The <i class="parameter"><tt>remote browse sync</tt></i> parameter of +<tt class="filename">smb.conf</tt> is used to announce to +another LMB that it must synchronise its NetBIOS name list with our +Samba LMB. It works ONLY if the Samba server that has this option is +simultaneously the LMB on its network segment. +</p><p> +The syntax of the <i class="parameter"><tt>remote browse sync</tt></i> parameter is: + +</p><pre class="programlisting"> +remote browse sync = <i class="replaceable"><tt>a.b.c.d</tt></i> +</pre><p> + +where <i class="replaceable"><tt>a.b.c.d</tt></i> is either the IP address of the +remote LMB or else is the network broadcast address of the remote segment. +</p></div></div><div class="sect1" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2905183"></a>WINS - The Windows Internetworking Name Server</h2></div></div><div></div></div><p> +Use of WINS (either Samba WINS <span class="emphasis"><em>or</em></span> MS Windows NT Server WINS) is highly +recommended. Every NetBIOS machine registers its name together with a +name_type value for each of several types of service it has available. +eg: It registers its name directly as a unique (the type 0x03) name. +It also registers its name if it is running the LanManager compatible +server service (used to make shares and printers available to other users) +by registering the server (the type 0x20) name. +</p><p> +All NetBIOS names are up to 15 characters in length. The name_type variable +is added to the end of the name - thus creating a 16 character name. Any +name that is shorter than 15 characters is padded with spaces to the 15th +character. ie: All NetBIOS names are 16 characters long (including the +name_type information). +</p><p> +WINS can store these 16 character names as they get registered. A client +that wants to log onto the network can ask the WINS server for a list +of all names that have registered the NetLogon service name_type. This saves +broadcast traffic and greatly expedites logon processing. Since broadcast +name resolution can not be used across network segments this type of +information can only be provided via WINS <span class="emphasis"><em>or</em></span> via statically configured +<tt class="filename">lmhosts</tt> files that must reside on all clients in the +absence of WINS. +</p><p> +WINS also serves the purpose of forcing browse list synchronisation by all +LMB's. LMB's must synchronise their browse list with the DMB (domain master +browser) and WINS helps the LMB to identify it's DMB. By definition this +will work only within a single workgroup. Note that the domain master browser +has NOTHING to do with what is referred to as an MS Windows NT Domain. The +later is a reference to a security environment while the DMB refers to the +master controller for browse list information only. +</p><p> +Use of WINS will work correctly only if EVERY client TCP/IP protocol stack +has been configured to use the WINS server/s. Any client that has not been +configured to use the WINS server will continue to use only broadcast based +name registration so that WINS may NEVER get to know about it. In any case, +machines that have not registered with a WINS server will fail name to address +lookup attempts by other clients and will therefore cause workstation access +errors. +</p><p> +To configure Samba as a WINS server just add +<i class="parameter"><tt>wins support = yes</tt></i> to the <tt class="filename">smb.conf</tt> +file [globals] section. +</p><p> +To configure Samba to register with a WINS server just add +<i class="parameter"><tt>wins server = a.b.c.d</tt></i> to your <tt class="filename">smb.conf</tt> file <i class="parameter"><tt>[globals]</tt></i> section. +</p><div class="important" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Important</h3><p> +Never use both <i class="parameter"><tt>wins support = yes</tt></i> together +with <i class="parameter"><tt>wins server = a.b.c.d</tt></i> +particularly not using it's own IP address. +Specifying both will cause <span class="application">nmbd</span> to refuse to start! +</p></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2905341"></a>Setting up a WINS server</h3></div></div><div></div></div><p> +Either a Samba machine or a Windows NT Server machine may be set up +as a WINS server. To set a Samba machine to be a WINS server you must +add the following option to the <tt class="filename">smb.conf</tt> file on the selected machine : +in the <i class="parameter"><tt>[globals]</tt></i> section add the line +</p><p> +</p><pre class="programlisting"> + wins support = yes +</pre><p> +</p><p> +Versions of Samba prior to 1.9.17 had this parameter default to +yes. If you have any older versions of Samba on your network it is +strongly suggested you upgrade to a recent version, or at the very +least set the parameter to 'no' on all these machines. +</p><p> +Machines with <i class="parameter"><tt>wins support = yes</tt></i> will keep a list of +all NetBIOS names registered with them, acting as a DNS for NetBIOS names. +</p><p> +You should set up only ONE WINS server. Do NOT set the +<i class="parameter"><tt>wins support = yes</tt></i> option on more than one Samba +server. +</p><p> +To set up a Windows NT Server as a WINS server you need to set up +the WINS service - see your NT documentation for details. Note that +Windows NT WINS Servers can replicate to each other, allowing more +than one to be set up in a complex subnet environment. As Microsoft +refuses to document these replication protocols, Samba cannot currently +participate in these replications. It is possible in the future that +a Samba->Samba WINS replication protocol may be defined, in which +case more than one Samba machine could be set up as a WINS server +but currently only one Samba server should have the +<i class="parameter"><tt>wins support = yes</tt></i> parameter set. +</p><p> +After the WINS server has been configured you must ensure that all +machines participating on the network are configured with the address +of this WINS server. If your WINS server is a Samba machine, fill in +the Samba machine IP address in the <span class="guilabel">Primary WINS Server</span> field of +the <span class="guilabel">Control Panel->Network->Protocols->TCP->WINS Server</span> dialogs +in Windows 95 or Windows NT. To tell a Samba server the IP address +of the WINS server add the following line to the <i class="parameter"><tt>[global]</tt></i> section of +all <tt class="filename">smb.conf</tt> files : +</p><p> +</p><pre class="programlisting"> + wins server = <name or IP address> +</pre><p> +</p><p> +where <name or IP address> is either the DNS name of the WINS server +machine or its IP address. +</p><p> +Note that this line MUST NOT BE SET in the <tt class="filename">smb.conf</tt> file of the Samba +server acting as the WINS server itself. If you set both the +<i class="parameter"><tt>wins support = yes</tt></i> option and the +<i class="parameter"><tt>wins server = <name></tt></i> option then +nmbd will fail to start. +</p><p> +There are two possible scenarios for setting up cross subnet browsing. +The first details setting up cross subnet browsing on a network containing +Windows 95, Samba and Windows NT machines that are not configured as +part of a Windows NT Domain. The second details setting up cross subnet +browsing on networks that contain NT Domains. +</p></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2905540"></a>WINS Replication</h3></div></div><div></div></div><p> +Samba-3 permits WINS replication through the use of the <tt class="filename">wrepld</tt> utility. +This tool is not currently capable of being used as it is still in active development. +As soon as this tool becomes moderately functional we will prepare man pages and enhance this +section of the documentation to provide usage and technical details. +</p></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2905565"></a>Static WINS Entries</h3></div></div><div></div></div><p> +Adding static entries to your Samba-3 WINS server is actually fairly easy. +All you have to do is add a line to <tt class="filename">wins.dat</tt>, typically +located in <tt class="filename">/usr/local/samba/var/locks</tt>. +</p><p> +Entries in <tt class="filename">wins.dat</tt> take the form of + +</p><pre class="programlisting"> +"NAME#TYPE" TTL ADDRESS+ FLAGS +</pre><p> + +where NAME is the NetBIOS name, TYPE is the NetBIOS type, TTL is the +time-to-live as an absolute time in seconds, ADDRESS+ is one or more +addresses corresponding to the registration and FLAGS are the NetBIOS +flags for the registration. +</p><p> +A typical dynamic entry looks like: +</p><pre class="programlisting"> +"MADMAN#03" 1055298378 192.168.1.2 66R +</pre><p> + +To make it static, all that has to be done is set the TTL to 0: + +</p><pre class="programlisting"> +"MADMAN#03" 0 192.168.1.2 66R +</pre><p> +</p><p> +Though this method works with early Samba-3 versions, there's a +possibility that it may change in future versions if WINS replication +is added. +</p></div></div><div class="sect1" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2905650"></a>Helpful Hints</h2></div></div><div></div></div><p> +The following hints should be carefully considered as they are stumbling points +for many new network administrators. +</p><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2905663"></a>Windows Networking Protocols</h3></div></div><div></div></div><div class="warning" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Warning</h3><p> +Do NOT use more than one (1) protocol on MS Windows machines +</p></div><p> +A very common cause of browsing problems results from installing more than +one protocol on an MS Windows machine. +</p><p> +Every NetBIOS machine takes part in a process of electing the LMB (and DMB) +every 15 minutes. A set of election criteria is used to determine the order +of precedence for winning this election process. A machine running Samba or +Windows NT will be biased so that the most suitable machine will predictably +win and thus retain it's role. +</p><p> +The election process is "fought out" so to speak over every NetBIOS network +interface. In the case of a Windows 9x machine that has both TCP/IP and IPX +installed and has NetBIOS enabled over both protocols the election will be +decided over both protocols. As often happens, if the Windows 9x machine is +the only one with both protocols then the LMB may be won on the NetBIOS +interface over the IPX protocol. Samba will then lose the LMB role as Windows +9x will insist it knows who the LMB is. Samba will then cease to function +as an LMB and thus browse list operation on all TCP/IP only machines will +fail. +</p><p><span class="emphasis"><em> +Windows 95, 98, 98se, Me are referred to generically as Windows 9x. +The Windows NT4, 2000, XP and 2003 use common protocols. These are roughly +referred to as the WinNT family, but it should be recognised that 2000 and +XP/2003 introduce new protocol extensions that cause them to behave +differently from MS Windows NT4. Generally, where a server does NOT support +the newer or extended protocol, these will fall back to the NT4 protocols. +</em></span></p><p> +The safest rule of all to follow it this - USE ONLY ONE PROTOCOL! +</p></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2905730"></a>Name Resolution Order</h3></div></div><div></div></div><p> +Resolution of NetBIOS names to IP addresses can take place using a number +of methods. The only ones that can provide NetBIOS name_type information +are: +</p><table class="simplelist" border="0" summary="Simple list"><tr><td>WINS: the best tool!</td></tr><tr><td>LMHOSTS: is static and hard to maintain.</td></tr><tr><td>Broadcast: uses UDP and can not resolve names across remote segments.</td></tr></table><p> +Alternative means of name resolution includes: +</p><table class="simplelist" border="0" summary="Simple list"><tr><td><tt class="filename">/etc/hosts</tt>: is static, hard to maintain, and lacks name_type info</td></tr><tr><td>DNS: is a good choice but lacks essential name_type info.</td></tr></table><p> +Many sites want to restrict DNS lookups and want to avoid broadcast name +resolution traffic. The <i class="parameter"><tt>name resolve order</tt></i> parameter is +of great help here. The syntax of the <i class="parameter"><tt>name resolve order</tt></i> +parameter is: +</p><pre class="programlisting"> +name resolve order = wins lmhosts bcast host +</pre><p> +<span class="emphasis"><em>or</em></span> +</p><pre class="programlisting"> +name resolve order = wins lmhosts (eliminates bcast and host) +</pre><p> +The default is: +</p><pre class="programlisting"> +name resolve order = host lmhost wins bcast +</pre><p> +where "host" refers the the native methods used by the Unix system +to implement the gethostbyname() function call. This is normally +controlled by <tt class="filename">/etc/host.conf</tt>, <tt class="filename">/etc/nsswitch.conf</tt> and <tt class="filename">/etc/resolv.conf</tt>. +</p></div></div><div class="sect1" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2905867"></a>Technical Overview of browsing</h2></div></div><div></div></div><p> +SMB networking provides a mechanism by which clients can access a list +of machines in a network, a so-called <i class="parameter"><tt>browse list</tt></i>. This list +contains machines that are ready to offer file and/or print services +to other machines within the network. Thus it does not include +machines which aren't currently able to do server tasks. The browse +list is heavily used by all SMB clients. Configuration of SMB +browsing has been problematic for some Samba users, hence this +document. +</p><p> +MS Windows 2000 and later, as with Samba 3 and later, can be +configured to not use NetBIOS over TCP/IP. When configured this way, +it is imperative that name resolution (using DNS/LDAP/ADS) be correctly +configured and operative. Browsing will NOT work if name resolution +from SMB machine names to IP addresses does not function correctly. +</p><p> +Where NetBIOS over TCP/IP is enabled use of a WINS server is highly +recommended to aid the resolution of NetBIOS (SMB) names to IP addresses. +WINS allows remote segment clients to obtain NetBIOS name_type information +that can NOT be provided by any other means of name resolution. +</p><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2905914"></a>Browsing support in Samba</h3></div></div><div></div></div><p> +Samba facilitates browsing. The browsing is supported by <span class="application">nmbd</span> +and is also controlled by options in the <tt class="filename">smb.conf</tt> file. +Samba can act as a local browse master for a workgroup and the ability +to support domain logons and scripts is now available. +</p><p> +Samba can also act as a domain master browser for a workgroup. This +means that it will collate lists from local browse masters into a +wide area network server list. In order for browse clients to +resolve the names they may find in this list, it is recommended that +both Samba and your clients use a WINS server. +</p><p> +Note that you should NOT set Samba to be the domain master for a +workgroup that has the same name as an NT Domain: on each wide area +network, you must only ever have one domain master browser per workgroup, +regardless of whether it is NT, Samba or any other type of domain master +that is providing this service. +</p><div class="note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p> +Nmbd can be configured as a WINS server, but it is not +necessary to specifically use Samba as your WINS server. MS Windows +NT4, Server or Advanced Server 2000 or 2003 can be configured as +your WINS server. In a mixed NT/2000/2003 server and Samba environment on +a Wide Area Network, it is recommended that you use the Microsoft +WINS server capabilities. In a Samba-only environment, it is +recommended that you use one and only one Samba server as your WINS server. +</p></div><p> +To get browsing to work you need to run nmbd as usual, but will need +to use the <i class="parameter"><tt>workgroup</tt></i> option in <tt class="filename">smb.conf</tt> +to control what workgroup Samba becomes a part of. +</p><p> +Samba also has a useful option for a Samba server to offer itself for +browsing on another subnet. It is recommended that this option is only +used for 'unusual' purposes: announcements over the internet, for +example. See <i class="parameter"><tt>remote announce</tt></i> in the +<tt class="filename">smb.conf</tt> man page. +</p></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2906021"></a>Problem resolution</h3></div></div><div></div></div><p> +If something doesn't work then hopefully the log.nmbd file will help +you track down the problem. Try a debug level of 2 or 3 for finding +problems. Also note that the current browse list usually gets stored +in text form in a file called <tt class="filename">browse.dat</tt>. +</p><p> +Note that if it doesn't work for you, then you should still be able to +type the server name as <tt class="filename">\\SERVER</tt> in filemanager then +hit enter and filemanager should display the list of available shares. +</p><p> +Some people find browsing fails because they don't have the global +<i class="parameter"><tt>guest account</tt></i> set to a valid account. Remember that the +IPC$ connection that lists the shares is done as guest, and thus you must +have a valid guest account. +</p><p><span class="emphasis"><em> +MS Windows 2000 and upwards (as with Samba) can be configured to disallow +anonymous (ie: Guest account) access to the IPC$ share. In that case, the +MS Windows 2000/XP/2003 machine acting as an SMB/CIFS client will use the +name of the currently logged in user to query the IPC$ share. MS Windows +9X clients are not able to do this and thus will NOT be able to browse +server resources. +</em></span></p><p> +The other big problem people have is that their broadcast address, +netmask or IP address is wrong (specified with the "interfaces" option +in <tt class="filename">smb.conf</tt>) +</p></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2906100"></a>Browsing across subnets</h3></div></div><div></div></div><p> +Since the release of Samba 1.9.17(alpha1), Samba has supported the +replication of browse lists across subnet boundaries. This section +describes how to set this feature up in different settings. +</p><p> +To see browse lists that span TCP/IP subnets (ie. networks separated +by routers that don't pass broadcast traffic), you must set up at least +one WINS server. The WINS server acts as a DNS for NetBIOS names, allowing +NetBIOS name to IP address translation to be done by doing a direct +query of the WINS server. This is done via a directed UDP packet on +port 137 to the WINS server machine. The reason for a WINS server is +that by default, all NetBIOS name to IP address translation is done +by broadcasts from the querying machine. This means that machines +on one subnet will not be able to resolve the names of machines on +another subnet without using a WINS server. +</p><p> +Remember, for browsing across subnets to work correctly, all machines, +be they Windows 95, Windows NT, or Samba servers must have the IP address +of a WINS server given to them by a DHCP server, or by manual configuration +(for Win95 and WinNT, this is in the TCP/IP Properties, under Network +settings) for Samba this is in the <tt class="filename">smb.conf</tt> file. +</p><div class="sect3" lang="en"><div class="titlepage"><div><div><h4 class="title"><a name="id2906150"></a>How does cross subnet browsing work ?</h4></div></div><div></div></div><p> +Cross subnet browsing is a complicated dance, containing multiple +moving parts. It has taken Microsoft several years to get the code +that achieves this correct, and Samba lags behind in some areas. +Samba is capable of cross subnet browsing when configured correctly. +</p><p> +Consider a network set up as follows : +</p><p> + +</p><pre class="programlisting"> + (DMB) + N1_A N1_B N1_C N1_D N1_E + | | | | | + ------------------------------------------------------- + | subnet 1 | + +---+ +---+ + |R1 | Router 1 Router 2 |R2 | + +---+ +---+ + | | + | subnet 2 subnet 3 | + -------------------------- ------------------------------------ + | | | | | | | | + N2_A N2_B N2_C N2_D N3_A N3_B N3_C N3_D + (WINS) +</pre><p> +</p><p> +Consisting of 3 subnets (1, 2, 3) connected by two routers +(R1, R2) - these do not pass broadcasts. Subnet 1 has 5 machines +on it, subnet 2 has 4 machines, subnet 3 has 4 machines. Assume +for the moment that all these machines are configured to be in the +same workgroup (for simplicity's sake). Machine N1_C on subnet 1 +is configured as Domain Master Browser (ie. it will collate the +browse lists for the workgroup). Machine N2_D is configured as +WINS server and all the other machines are configured to register +their NetBIOS names with it. +</p><p> +As all these machines are booted up, elections for master browsers +will take place on each of the three subnets. Assume that machine +N1_C wins on subnet 1, N2_B wins on subnet 2, and N3_D wins on +subnet 3 - these machines are known as local master browsers for +their particular subnet. N1_C has an advantage in winning as the +local master browser on subnet 1 as it is set up as Domain Master +Browser. +</p><p> +On each of the three networks, machines that are configured to +offer sharing services will broadcast that they are offering +these services. The local master browser on each subnet will +receive these broadcasts and keep a record of the fact that +the machine is offering a service. This list of records is +the basis of the browse list. For this case, assume that +all the machines are configured to offer services so all machines +will be on the browse list. +</p><p> +For each network, the local master browser on that network is +considered 'authoritative' for all the names it receives via +local broadcast. This is because a machine seen by the local +master browser via a local broadcast must be on the same +network as the local master browser and thus is a 'trusted' +and 'verifiable' resource. Machines on other networks that +the local master browsers learn about when collating their +browse lists have not been directly seen - these records are +called 'non-authoritative'. +</p><p> +At this point the browse lists look as follows (these are +the machines you would see in your network neighborhood if +you looked in it on a particular network right now). +</p><p> +</p><div class="table"><a name="id2906267"></a><p class="title"><b>Table 10.1. Browse subnet example 1</b></p><table summary="Browse subnet example 1" border="1"><colgroup><col><col><col></colgroup><thead><tr><th align="left">Subnet</th><th align="left">Browse Master</th><th align="left">List</th></tr></thead><tbody><tr><td align="left">Subnet1</td><td align="left">N1_C</td><td align="left">N1_A, N1_B, N1_C, N1_D, N1_E</td></tr><tr><td align="left">Subnet2</td><td align="left">N2_B</td><td align="left">N2_A, N2_B, N2_C, N2_D</td></tr><tr><td align="left">Subnet3</td><td align="left">N3_D</td><td align="left">N3_A, N3_B, N3_C, N3_D</td></tr></tbody></table></div><p> +</p><p> +Note that at this point all the subnets are separate, no +machine is seen across any of the subnets. +</p><p> +Now examine subnet 2. As soon as N2_B has become the local +master browser it looks for a Domain master browser to synchronize +its browse list with. It does this by querying the WINS server +(N2_D) for the IP address associated with the NetBIOS name +WORKGROUP<1B>. This name was registered by the Domain master +browser (N1_C) with the WINS server as soon as it was booted. +</p><p> +Once N2_B knows the address of the Domain master browser it +tells it that is the local master browser for subnet 2 by +sending a MasterAnnouncement packet as a UDP port 138 packet. +It then synchronizes with it by doing a NetServerEnum2 call. This +tells the Domain Master Browser to send it all the server +names it knows about. Once the domain master browser receives +the MasterAnnouncement packet it schedules a synchronization +request to the sender of that packet. After both synchronizations +are done the browse lists look like : +</p><p> +</p><div class="table"><a name="id2906382"></a><p class="title"><b>Table 10.2. Browse subnet example 2</b></p><table summary="Browse subnet example 2" border="1"><colgroup><col><col><col></colgroup><thead><tr><th align="left">Subnet</th><th align="left">Browse Master</th><th align="left">List</th></tr></thead><tbody><tr><td align="left">Subnet1</td><td align="left">N1_C</td><td align="left">N1_A, N1_B, N1_C, N1_D, N1_E, N2_A(*), N2_B(*), N2_C(*), N2_D(*)</td></tr><tr><td align="left">Subnet2</td><td align="left">N2_B</td><td align="left">N2_A, N2_B, N2_C, N2_D, N1_A(*), N1_B(*), N1_C(*), N1_D(*), N1_E(*)</td></tr><tr><td align="left">Subnet3</td><td align="left">N3_D</td><td align="left">N3_A, N3_B, N3_C, N3_D</td></tr></tbody></table></div><p> + +Servers with a (*) after them are non-authoritative names. +</p><p> +At this point users looking in their network neighborhood on +subnets 1 or 2 will see all the servers on both, users on +subnet 3 will still only see the servers on their own subnet. +</p><p> +The same sequence of events that occured for N2_B now occurs +for the local master browser on subnet 3 (N3_D). When it +synchronizes browse lists with the domain master browser (N1_A) +it gets both the server entries on subnet 1, and those on +subnet 2. After N3_D has synchronized with N1_C and vica-versa +the browse lists look like. +</p><p> +</p><div class="table"><a name="id2906481"></a><p class="title"><b>Table 10.3. Browse subnet example 3</b></p><table summary="Browse subnet example 3" border="1"><colgroup><col><col><col></colgroup><thead><tr><th align="left">Subnet</th><th align="left">Browse Master</th><th align="left">List</th></tr></thead><tbody><tr><td align="left">Subnet1</td><td align="left">N1_C</td><td align="left">N1_A, N1_B, N1_C, N1_D, N1_E, N2_A(*), N2_B(*), N2_C(*), N2_D(*), N3_A(*), N3_B(*), N3_C(*), N3_D(*)</td></tr><tr><td align="left">Subnet2</td><td align="left">N2_B</td><td align="left">N2_A, N2_B, N2_C, N2_D, N1_A(*), N1_B(*), N1_C(*), N1_D(*), N1_E(*)</td></tr><tr><td align="left">Subnet3</td><td align="left">N3_D</td><td align="left">N3_A, N3_B, N3_C, N3_D, N1_A(*), N1_B(*), N1_C(*), N1_D(*), N1_E(*), N2_A(*), N2_B(*), N2_C(*), N2_D(*)</td></tr></tbody></table></div><p> + +Servers with a (*) after them are non-authoritative names. +</p><p> +At this point users looking in their network neighborhood on +subnets 1 or 3 will see all the servers on all subnets, users on +subnet 2 will still only see the servers on subnets 1 and 2, but not 3. +</p><p> +Finally, the local master browser for subnet 2 (N2_B) will sync again +with the domain master browser (N1_C) and will receive the missing +server entries. Finally - and as a steady state (if no machines +are removed or shut off) the browse lists will look like : +</p><p> +</p><div class="table"><a name="id2906581"></a><p class="title"><b>Table 10.4. Browse subnet example 4</b></p><table summary="Browse subnet example 4" border="1"><colgroup><col><col><col></colgroup><thead><tr><th align="left">Subnet</th><th align="left">Browse Master</th><th align="left">List</th></tr></thead><tbody><tr><td align="left">Subnet1</td><td align="left">N1_C</td><td align="left">N1_A, N1_B, N1_C, N1_D, N1_E, N2_A(*), N2_B(*), N2_C(*), N2_D(*), N3_A(*), N3_B(*), N3_C(*), N3_D(*)</td></tr><tr><td align="left">Subnet2</td><td align="left">N2_B</td><td align="left">N2_A, N2_B, N2_C, N2_D, N1_A(*), N1_B(*), N1_C(*), N1_D(*), N1_E(*), N3_A(*), N3_B(*), N3_C(*), N3_D(*)</td></tr><tr><td align="left">Subnet3</td><td align="left">N3_D</td><td align="left">N3_A, N3_B, N3_C, N3_D, N1_A(*), N1_B(*), N1_C(*), N1_D(*), N1_E(*), N2_A(*), N2_B(*), N2_C(*), N2_D(*)</td></tr></tbody></table></div><p> + +Servers with a (*) after them are non-authoritative names. +</p><p> +Synchronizations between the domain master browser and local +master browsers will continue to occur, but this should be a +steady state situation. +</p><p> +If either router R1 or R2 fails the following will occur: +</p><div class="orderedlist"><ol type="1"><li><p> + Names of computers on each side of the inaccessible network fragments + will be maintained for as long as 36 minutes, in the network neighbourhood + lists. + </p></li><li><p> + Attempts to connect to these inaccessible computers will fail, but the + names will not be removed from the network neighbourhood lists. + </p></li><li><p> + If one of the fragments is cut off from the WINS server, it will only + be able to access servers on its local subnet, by using subnet-isolated + broadcast NetBIOS name resolution. The effects are similar to that of + losing access to a DNS server. + </p></li></ol></div></div></div></div><div class="sect1" lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a name="id2906720"></a>Common Errors</h2></div></div><div></div></div><p> +Many questions are asked on the mailing lists regarding browsing. The majority of browsing +problems originate out of incorrect configuration of NetBIOS name resolution. Some are of +particular note. +</p><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2906735"></a>How can one flush the Samba NetBIOS name cache without restarting Samba?</h3></div></div><div></div></div><p> +Samba's nmbd process controls all browse list handling. Under normal circumstances it is +safe to restart nmbd. This will effectively flush the Samba NetBIOS name cache and cause it +to be rebuilt. Note that this does NOT make certain that a rogue machine name will not re-appear +in the browse list. When nmbd is taken out of service another machine on the network will +become the browse master. This new list may still have the rogue entry in it. If you really +want to clear a rogue machine from the list then every machine on the network will need to be +shut down and restarted at after all machines are down. Failing a complete restart, the only +other thing you can do is wait until the entry times out and is then flushed from the list. +This may take a long time on some networks (months). +</p></div><div class="sect2" lang="en"><div class="titlepage"><div><div><h3 class="title"><a name="id2906764"></a>My client reports "This server is not configured to list shared resources"</h3></div></div><div></div></div><p> +Your guest account is probably invalid for some reason. Samba uses the +guest account for browsing in smbd. Check that your guest account is +valid. +</p><p>See also <i class="parameter"><tt>guest account</tt></i> in the <tt class="filename">smb.conf</tt> man page.</p></div></div></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="optional.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="optional.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="passdb.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">Part III. Advanced Configuration </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> Chapter 11. Account Information Databases</td></tr></table></div></body></html> |