From 8f8a9f01909ba29e2b781310baeeaaddc3f15f0d Mon Sep 17 00:00:00 2001 From: "Gerald W. Carter" Date: Tue, 22 Apr 2008 10:09:40 -0500 Subject: Moving docs tree to docs-xml to make room for generated docs in the release tarball. (This used to be commit 9f672c26d63955f613088489c6efbdc08b5b2d14) --- docs-xml/Samba3-HOWTO/TOSHARG-NetworkBrowsing.xml | 2218 +++++++++++++++++++++ 1 file changed, 2218 insertions(+) create mode 100644 docs-xml/Samba3-HOWTO/TOSHARG-NetworkBrowsing.xml (limited to 'docs-xml/Samba3-HOWTO/TOSHARG-NetworkBrowsing.xml') diff --git a/docs-xml/Samba3-HOWTO/TOSHARG-NetworkBrowsing.xml b/docs-xml/Samba3-HOWTO/TOSHARG-NetworkBrowsing.xml new file mode 100644 index 0000000000..3c86438c2f --- /dev/null +++ b/docs-xml/Samba3-HOWTO/TOSHARG-NetworkBrowsing.xml @@ -0,0 +1,2218 @@ + + + + + &author.jht; + &author.jelmer; + + JonathanJohnson + + Sutinen Consulting, Inc. +
jon@sutinen.com
+ + + July 5, 1998 + Updated: September 20, 2006 + + +Network Browsing + + +browsing across subnets +resolution of NetBIOS names +browse list handling +WINS +This chapter 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; however, WINS is +not involved in browse list handling except by way of name-to-address resolution. + + + +WINS +What is WINS? + + +WINS is a facility that provides resolution of a NetBIOS name to its IP address. WINS is like a +Dynamic-DNS service for NetBIOS networking names. + + + +Windows 2000 +NetBIOS over TCP/IP +DNS +ADS +MS Windows 2000 and later versions can be configured to operate with no NetBIOS +over TCP/IP. Samba-3 and later versions also support this mode of operation. +When the use of NetBIOS over TCP/IP has been disabled, 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. + + + +Features and Benefits + + +Charles Dickens once referred to the past in these words: It was the best of times, +it was the worst of times. The more we look back, the more we long for what was and +hope it never returns. + + + + +NetBIOS +NetBIOS networking +fickle +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. + + + +For those not familiar with botanical problems in Australia, Paterson's Curse, +Echium plantagineum, was introduced to Australia from Europe during the mid-19th +century. Since then it has spread rapidly. The high seed production, with densities of +thousands of seeds per square meter, a seed longevity of more than 7 years, and an +ability to germinate at any time of year, given the right conditions, are some of the +features that make it such a persistent weed. + + + +Network Basic Input/Output SystemNetBIOS +SMB +NetBIOS +TCP/IP +Windows network clients +In this chapter we explore vital aspects of Server Message Block (SMB) 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. + + + +WINS +MS WINS +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 effect stable WINS operations beyond the normal scope of MS WINS. + + + +NetBIOS over TCP/IP +NetBIOS disabled +WINS +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 operate with +support for NetBIOS disabled, in which case WINS is of no relevance. Samba supports this also. + + + +NetBIOS disabled +DNS +WINS +For those networks on which NetBIOS has been disabled (i.e., WINS is not required), +the use of DNS is necessary for hostname resolution. + + + + + +What Is Browsing? + + +browsing +Network Neighborhood +shares +printers available +To most people, browsing means 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. + + + +What seems so simple is in fact a complex interaction of different technologies. +The technologies (or methods) employed in making all of this work include: + + + + MS Windows machines register their presence to the network. + Machines announce themselves to other machines on the network. + One or more machines on the network collate the local announcements. + The client machine finds the machine that has the collated list of machines. + The client machine is able to resolve the machine names to IP addresses. + The client machine is able to connect to a target machine. + + + +browse list management +name resolution +nmbd +The Samba application that controls browse list management and name resolution is +called nmbd. The configuration parameters involved in nmbd's operation are: + + + +Browsing options: + + + + + + (*) + (*) + (*) + + + + + +Name Resolution Method: + + + (*) + + + +WINS options: + + + + + (*) + (*) + + + + +Those marked with an (*) are the only options that commonly may need to be modified. Even if none of these +parameters is set, nmbd will still do its job. + + + +WINS +WINS Server +WINS Support +nmbd +mutually exclusive options +For Samba, the WINS Server and WINS Support are mutually exclusive options. When nmbd is +started it will fail to execute if both options are set in the &smb.conf; file. The nmbd +understands that when it spawns an instance of itself to run as a WINS server that it has to use its own WINS +server also. + + + + + +Discussion + + +SMB-based messaging +NetBIOS +NetBIOS +phasing out NetBIOS +All MS Windows networking uses SMB-based messaging. SMB messaging may be implemented with or without NetBIOS. +MS Windows 200x supports NetBIOS over TCP/IP for backwards compatibility. Microsoft appears intent on phasing +out NetBIOS support. + + + +NetBIOS over TCP/IP + + +encapsulating +broadcast +unicast +UDP +Samba implements NetBIOS, as does MS Windows NT/200x/XP, by encapsulating it over TCP/IP. +NetBIOS-based networking uses broadcast messaging to effect browse list management. When running NetBIOS over +TCP/IP, this uses UDP-based messaging. UDP messages can be broadcast or unicast. + + + +UDP +Normally, only unicast UDP messaging can be forwarded by routers. The +parameter to smb.conf helps to project browse announcements to remote network segments via unicast UDP. +Similarly, the parameter of &smb.conf; implements browse list +collation using unicast UDP. + + + +The methods used by MS Windows to perform name lookup requests (name resolution) is determined by a +configuration parameter called the NetBIOS node-type. There are four basic NetBIOS node types: + + +b-node +p-node +m-node +h-node +node-type +WINS +broadcast +unicast + + b-node (type 0x01): The Windows client will use only + NetBIOS broadcast requests using UDP broadcast. + p-node (type 0x02): The Windows client will use point-to-point + (NetBIOS unicast) requests using UDP unicast directed to a WINS server. + m-node (type 0x04): The Windows client will first use + NetBIOS broadcast requests using UDP broadcast, then it will use (NetBIOS unicast) + requests using UDP unicast directed to a WINS server. + h-node (type 0x08): The Windows client will use + (NetBIOS unicast) requests using UDP unicast directed to a WINS server, then it will use + NetBIOS broadcast requests using UDP broadcast. + + + +h-node +hybrid +enables NetBIOS over TCP/IP +WINS +broadcast-based +name resolution +The default Windows network client (or server) network configuration enables NetBIOS over TCP/IP +and b-node configuration. The use of WINS makes most sense with h-node (hybrid mode) operation so that +in the event of a WINS breakdown or non-availability, the client can use broadcast-based name resolution. + + + +LMBLocal Master Browser +Local Master Browser +SMB +nmbd +WINS +cross-segment browsing +network segment +In those networks where Samba is the only SMB server technology, wherever possible nmbd +should be configured on one machine as the WINS server. This makes it easy to manage the browsing environment. +If each network segment is configured with its own Samba WINS server, then the only way to get cross-segment +browsing to work is by using the and the parameters to your &smb.conf; file. + + + +WINS +If only one WINS server is used for an entire multisegment network, then +the use of the and the + parameters should not be necessary. + + + +replicationWINS +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-3.0.20 release. Hopefully, this will become a +supported feature of one of the Samba-3 release series. The delay is caused by the fact that this feature has +not been of sufficient significance to inspire someone to pay a developer to complete it. + + + +WINS +MS-WINS replication +redundancy +DNS +NetBIOSless SMB over TCP/IP +local names +subnets +multiple WINS servers +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 nmbd 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 + and to effect 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 +(i.e., an if all else fails scenario). NetBIOS over TCP/IP is an ugly and difficult to manage +protocol. Its replacement, NetBIOSless SMB over TCP/IP is not without its own manageability concerns. NetBIOS +based networking is a life of compromise and trade-offs. WINS stores information that cannot be stored in +DNS; consequently, DNS is a poor substitute for WINS given that when NetBIOS over TCP/IP is used, Windows +clients are designed to use WINS. + + + +broadcast messages +repeated intervals +across network segments +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 stabilize, particularly across network segments. + + + +Windows 200x/XP +When an MS Windows 200x/XP system attempts to resolve a host name to an IP address, it follows a defined path: + + + + + Checks the hosts file. It is located in %SystemRoot%\System32\Drivers\etc. + + + + Does a DNS lookup. + + + + Checks the NetBIOS name cache. + + + + Queries the WINS server. + + + + Does a broadcast name lookup over UDP. + + + + Looks up entries in LMHOSTS, located in %SystemRoot%\System32\Drivers\etc. + + + + +WINS +NetBIOS over TCP/IP +name lookups +DNS +Given the nature of how the NetBIOS over TCP/IP protocol is implemented, only WINS is capable of resolving +with any reliability name lookups for service-oriented names such as TEMPTATION<1C> &smbmdash; a NetBIOS +name query that seeks to find network logon servers. DNS has no concept of service-oriented names such as +this. In fact, the Microsoft ADS implementation specifically manages a whole range of extended +service-oriented DNS entries. This type of facility is not implemented and is not supported for the NetBIOS +over TCP/IP protocol namespace. + + + + + +TCP/IP without NetBIOS + + +NetBIOS +NetBIOS-less +DNS +All TCP/IP-enabled systems use various forms of hostname resolution. The primary +methods for TCP/IP hostname resolution involve either a static file (/etc/hosts) +or the Domain Name System (DNS). DNS is the technology that makes +the Internet usable. DNS-based hostname resolution is supported by nearly all +TCP/IP-enabled systems. Only a few embedded TCP/IP systems do not support DNS. + + + +DNS +DDNS +ipconfig +Dynamic DNSDDNS +Windows 200x/XP can register its hostname with a Dynamic DNS server (DDNS). It is possible to force register with a +dynamic DNS server in Windows 200x/XP using ipconfig /registerdns. + + + +ADS +DNS +severely impaired +With Active Directory, 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 unable to locate each +other, so network services consequently will be severely impaired. + + + +raw SMB over TCP/IP +No NetBIOS layer +NetBIOS +domain member server +DNS +ADS +Use of raw SMB over TCP/IP (No NetBIOS layer) can be done only with Active Directory domains. Samba is not an +Active Directory domain controller: ergo, it is not possible to run Samba as a domain controller and at the same +time not use NetBIOS. Where Samba is used as an Active Directory domain member server +(DMS) it is possible to configure Samba to not use NetBIOS over TCP/IP. A Samba DMS can integrate fully into +an Active Directory domain, however, if NetBIOS over TCP/IP is disabled, it is necessary to manually create +appropriate DNS entries for the Samba DMS because they will not be automatically generated either by Samba, or +by the ADS environment. + + + + + +DNS and Active Directory + + +DNSActive Directory +DDNS +ADS +SRV records +DNSSRV records +Occasionally we hear from UNIX network administrators who want to use a UNIX-based DDNS server in place +of the Microsoft DNS server. While this might be desirable to some, the MS Windows 200x DNS server is +autoconfigured 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 (SRV records) so MS Active Directory clients can resolve +hostnames to locate essential network services. The following are some of the default service records that +Active Directory requires: + + + +DDNS +ADS +BIND9 +The use of DDNS is highly recommended with Active Directory, in which case the use of BIND9 is preferred for +its ability to adequately support the SRV (service) records that are needed for Active Directory. Of course, +when running ADS, it makes sense to use Microsoft's own DDNS server because of the natural affinity between ADS +and MS DNS. + + + + + _ldap._tcp.pdc._msdcs.Domain + + + This provides the address of the Windows NT PDC for the domain. + + + + + _ldap._tcp.pdc._msdcs.DomainTree + + + Resolves the addresses of global catalog servers in the domain. + + + + + _ldap._tcp.site.sites.writable._msdcs.Domain + + + Provides list of domain controllers based on sites. + + + + + _ldap._tcp.writable._msdcs.Domain + + + Enumerates list of domain controllers that have the writable copies of the Active Directory data store. + + + + + _ldap._tcp.GUID.domains._msdcs.DomainTree + + + Entry used by MS Windows clients to locate machines using the global unique identifier. + + + + + _ldap._tcp.Site.gc._msdcs.DomainTree + + + Used by Microsoft Windows clients to locate the site configuration-dependent global catalog server. + + + + + + + Specific entries used by Microsoft clients to locate essential services for an example domain + called quenya.org include: + + + + + _kerberos._udp.quenya.org &smbmdash; Used to contact the KDC server via UDP. + This entry must list port 88 for each KDC. + + + + _kpasswd._udp.quenya.org &smbmdash; Used to locate the kpasswd server + when a user password change must be processed. This record must list port 464 on the + master KDC. + + + + _kerberos._tcp.quenya.org &smbmdash; Used to locate the KDC server via TCP. + This entry must list port 88 for each KDC. + + + + _ldap._tcp.quenya.org &smbmdash; Used to locate the LDAP service on the PDC. + This record must list port 389 for the PDC. + + + + _kpasswd._tcp.quenya.org &smbmdash; Used to locate the kpasswd server + to permit user password changes to be processed. This must list port 464. + + + + _gc._tcp.quenya.org &smbmdash; Used to locate the global catalog server for the + top of the domain. This must list port 3268. + + + + + The following records are also used by the Windows domain member client to locate vital + services on the Windows ADS domain controllers. + + + + + _ldap._tcp.pdc._msdcs.quenya.org + + + + _ldap.gc._msdcs.quenya.org + + + + _ldap.default-first-site-name._sites.gc._msdcs.quenya.org + + + + _ldap.{SecID}.domains._msdcs.quenya.org + + + + _ldap._tcp.dc._msdcs.quenya.org + + + + _kerberos._tcp.dc._msdcs.quenya.org + + + + _ldap.default-first-site-name._sites.dc._msdcs.quenya.org + + + + _kerberos.default-first-site-name._sites.dc._msdcs.queyna.org + + + + SecID._msdcs.quenya.org + + + + + Presence of the correct DNS entries can be validated by executing: + +&rootprompt; dig @frodo -t any _ldap._tcp.dc._msdcs.quenya.org + +; <lt;>> DiG 9.2.2 <lt;>> @frodo -t any _ldap._tcp.dc._msdcs.quenya.org +;; global options: printcmd +;; Got answer: +;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 3072 +;; flags: qr aa rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 0, ADDITIONAL: 2 + + +;; QUESTION SECTION: +;_ldap._tcp.dc._msdcs.quenya.org. IN ANY + + +;; ANSWER SECTION: +_ldap._tcp.dc._msdcs.quenya.org. 600 IN SRV 0 100 389 frodo.quenya.org. +_ldap._tcp.dc._msdcs.quenya.org. 600 IN SRV 0 100 389 noldor.quenya.org. + + +;; ADDITIONAL SECTION: +frodo.quenya.org. 3600 IN A 10.1.1.16 +noldor.quenya.org. 1200 IN A 10.1.1.17 + + +;; Query time: 0 msec +;; SERVER: frodo#53(10.1.1.16) +;; WHEN: Wed Oct 7 14:39:31 2004 +;; MSG SIZE rcvd: 171 + + + + + + + + +How Browsing Functions + + +register NetBIOS names +LMHOSTS +DNS +WINS +WINS server address +MS Windows machines register their NetBIOS names (i.e., the machine name for each service type in operation) +on startup. 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, +whether or not DNS for NetBIOS name resolution is enabled, and so on. + + + +WINS server +name lookups +UDP +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 +parameter). + + + +WINS +UDP unicast +name resolution across routed networks +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. + + + +LMB +local master browserLMB +WINS +LMHOSTS +DMB +browse list +election +election criteria +During the startup process, an election takes place to create a local master browser (LMB) if one does not +already exist. On each NetBIOS network one machine will be elected to function as the domain master browser +(DMB). This domain browsing has nothing to do with MS security Domain Control. Instead, the DMB serves the +role of contacting each LMB (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 to 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 DMB. + + + +WINS server +DMB +NetBIOS name type +n security context +network segment +authoritive +browse list maintainers +LMB +Where a WINS server is used, the DMB registers its IP address with the WINS server using the name of the +domain and the NetBIOS name type 1B (e.g., DOMAIN<1B>). All LMBs register their IP addresses with the WINS +server, also with the name of the domain and the NetBIOS name type of 1D. The 1B name is unique to one +server within the domain security context, and only one 1D name is registered for each network segment. +Machines that have registered the 1D name will be authoritive browse list maintainers for the network segment +they are on. The DMB is responsible for synchronizing the browse lists it obtains from the LMBs. + + + +name resolution +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 or addresses. + + + +browsing intrinsics +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. + + + +forced synchronization +LMB +bridges networks +cross-subnet browsing +DNS +/etc/hosts +Samba supports a feature that allows forced synchronization of browse lists across routed networks using the + parameter in the &smb.conf; file. This causes Samba to contact the +LMB on a remote network and to request browse list synchronization. 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 parameter provides +browse list synchronization &smbmdash; 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, /etc/hosts, and so on. + + + +Configuring Workgroup Browsing + + +cross-subnet browsing +DMB +PDC +LMB +isolated workgroup +workgroup +To configure cross-subnet browsing on a network containing machines in a workgroup, not an NT domain, you need +to set up one Samba server to be the DMB (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 DMB is to collate the browse lists +from LMB on all the subnets that have a machine participating in the workgroup. Without one machine configured +as a DMB, each subnet would be an isolated workgroup unable to see any machines on another subnet. It is the +presence of a DMB that makes cross-subnet browsing possible for a workgroup. + + + +DMB +In a workgroup environment the DMB must be a Samba server, and there must only be one DMB per workgroup name. +To set up a Samba server as a DMB, set the following option in the section +of the &smb.conf; file: + + + + +yes + + + + +DMB +LMB +The DMB should preferably be the LMB for its own subnet. In order to achieve this, set the following options +in the section of the &smb.conf; file as shown in Domain Master Browser smb.conf + + + +Domain Master Browser smb.conf + + +yes +yes +yes +65 + + + + +DMB +WINS server +The DMB may be the same machine as the WINS server, if necessary. + + + +subnets +LMB +rebooted +Next, you should ensure that each of the subnets contains a machine that can act as an LMB for the workgroup. +Any MS Windows NT/200x/XP machine should be able to do this, as will Windows 9x/Me machines (although these +tend to get rebooted more often, so it is not such a good idea to use them). To make a Samba server an LMB, +set the following options in the section of the &smb.conf; file as shown in +Local master browser smb.conf + + + +Local master browser smb.conf + + +no +yes +yes +65 + + + + +LMB +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 LMB. + + + +LMB +browser election +The parameter allows Samba to act as a +LMB. The causes nmbd +to force a browser election on startup and the +parameter sets Samba high enough so it should win any browser elections. + + + +disable LMB +If you have an NT machine on the subnet that you wish to be the LMB, you can disable Samba from +becoming an LMB by setting the following options in the section of the +&smb.conf; file as shown in smb.conf for Not Being a Master Browser. + + + + +smb.conf for Not Being a Master Browser + + +no +no +no +0 + + + + + + + +Domain Browsing Configuration + + +DMB +PDC +registers +WINS +If you are adding Samba servers to a Windows NT domain, then you must not set up a Samba server as a DMB. By +default, a Windows NT PDC for a domain is also the DMB for that domain. Network browsing may break if a Samba +server other than the PDC registers the DMB NetBIOS name (DOMAIN<1B>) with +WINS. + + + +Local Master Browser +For subnets other than the one containing the Windows NT PDC, you may set up Samba servers as LMBs as +described. To make a Samba server a Local Master Browser, set the following options in the section of the &smb.conf; file as shown in Local Master Browser +smb.conf + + + +Local Master Browser smb.conf + + +no +yes +yes +65 + + + + +election +LMB +If you wish to have a Samba server fight the election with machines on the same subnet, you may set the + parameter to lower levels. By doing this you can tune the order of machines +that will become LMBs if they are running. For more details on this, refer to Forcing Samba to Be the Master. + + + +domain members +browser elections +LMB +If you have Windows NT machines that are members of the domain on all subnets and you are sure they will +always be running, you can disable Samba from taking part in browser elections and ever becoming an LMB by +setting the following options in the section of the &smb.conf; file as shown +in &smb.conf; for Not Being a master browser + + + + +&smb.conf; for Not Being a master browser + +no +no +no +0 + + + + + + +Forcing Samba to Be the Master + + +master browser +election process +broadcasts +election packet +bias +election +precedence +Who becomes the master browser is determined by an election process using broadcasts. Each election packet +contains a number of parameters that determine what precedence (bias) a host should have in the election. By +default Samba uses a low precedence and thus loses elections to just about every Windows network server or +client. + + + +If you want Samba to win elections, set the global option in &smb.conf; to a +higher number. It defaults to 20. Using 34 would make it win all elections over every other system (except +other Samba systems). + + + +An of two would make it beat Windows for Workgroups and Windows 9x/Me, but +not MS Windows NT/200x Server. An MS Windows NT/200x Server domain controller uses level 32. The maximum os +level is 255. + + + +force an election +potential master browsers +local subnet +LMB +If you want Samba to force an election on startup, set the global +option in &smb.conf; to yes. Samba will then have a slight advantage over other +potential master browsers that are not preferred master browsers. Use this parameter with care, because if +you have two hosts (whether they are Windows 9x/Me or NT/200x/XP or Samba) on the same local subnet both set +with to yes, then periodically and continually +they will force an election in order to become the LMB. + + + +DMB +LAN +WAN +LMB +broadcast isolated subnet +If you want Samba to be a DMB, then it is recommended that you also set to yes, because Samba will not become a DMB for the whole of +your LAN or WAN if it is not also a LMB on its own broadcast isolated subnet. + + + +DMB +automatic redundancy +UDP +network bandwidth +browser elections +It is possible to configure two Samba servers to attempt to become the DMB for a domain. The first server that +comes up will be the DMB. All other Samba servers will attempt to become the DMB every 5 minutes. They will +find that another Samba server is already the DMB and will fail. This provides automatic redundancy should the +current DMB fail. The network bandwidth overhead of browser elections is relatively small, requiring +approximately four UDP packets per machine per election. The maximum size of a UDP packet is 576 bytes. + + + + + +Making Samba the Domain Master + + +DMB +collating +browse lists +browsing +The domain master browser is responsible for collating the browse lists of multiple subnets so browsing can +occur between subnets. You can make Samba act as the domain master browser by setting yes in &smb.conf;. By default it will not be a domain master browser. + + + +workgroup +network browsing problems +Do not set Samba to be the domain master for a workgroup that has the same name as an NT/200x domain. If +Samba is configured to be the domain master for a workgroup that is present on the same network as a Windows +NT/200x domain that has the same name, network browsing problems will certainly be experienced. + + + +When Samba is the domain master and the master browser, it will listen for master announcements (made roughly +every 12 minutes) from LMBs on other subnets and then contact them to synchronize browse lists. + + + +win election +force election +If you want Samba to be the domain master, you should also set the high +enough to make sure it wins elections, and set to +yes, to get Samba to force an election on startup. + + + +WINS server +resolve NetBIOS names +All 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: + + + + + +LMB +DMB + LMBs will be unable to find a DMB because they will be looking only on the local subnet. + + + + + +domain-wide browse list + 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. + + + + + +WINS +If, however, both Samba and your clients are using a WINS server, then: + + + + + + LMBs will contact the WINS server and, as long as Samba has registered that it is a DMB with the WINS + server, the LMB will receive Samba's IP address as its DMB. + + + + + + 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.. + + + + + + + +Note about Broadcast Addresses + + +zero-based broadcast +If your network uses a zero-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 zeros broadcast, and you will probably find that +browsing and name lookups will not work. + + + + +Multiple Interfaces + + +multiple network interfaces +Samba supports machines with multiple network interfaces. If you have multiple interfaces, you will +need to use the option in &smb.conf; to configure them. For example, the +machine you are working with has 4 network interfaces; eth0, eth1, +eth2, eth3 and only interfaces eth1 and +eth4 should be used by Samba. In this case, the following &smb.conf; file entries would +permit that intent: + +eth1, eth4 +Yes + +port 135 +port 137 +port 138 +port 139 +port 445 +UDP +TCP +The Yes is necessary to exclude TCP/IP session +services (ports 135, 139, and 445) over the interfaces that are not specified. Please be aware that +nmbd will listen for incoming UDP port 137 packets on the unlisted interfaces, but it will +not answer them. It will, however, send its broadcast packets over the unlisted interfaces. Total isolation of +ethernet interface requires the use of a firewall to block ports 137 and 138 (UDP), and ports 135, 139, and +445 (TCP) on all network interfaces that must not be able to access the Samba server. + + + + + +Use of the Remote Announce Parameter + +The parameter of &smb.conf; can be used to forcibly ensure that all +the NetBIOS names on a network get announced to a remote network. The syntax of the parameter is: + +192.168.12.23 [172.16.21.255] ... + +or + +192.168.12.23/MIDEARTH [172.16.21.255/ELVINDORF] ... + + +where: + + 192.168.12.23 and 172.16.21.255 + +LMBLocal Master Browser +Local Master Browser + is either the LMB IP address or the broadcast address of the remote network. + That is, the LMB is at 192.168.1.23, or the address could be given as 172.16.21.255 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. + + + + + WORKGROUP + 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, our NetBIOS machine names will end up looking like + they belong to that workgroup. This may cause name resolution problems and should be avoided. + + + + + + + + +Use of the Remote Browse Sync Parameter + + +LMB +synchronize +The parameter of &smb.conf; is used to announce to another LMB that +it must synchronize its NetBIOS name list with our Samba LMB. This works only if the Samba server that has +this option is simultaneously the LMB on its network segment. + + + +The syntax of the parameter is: + + +192.168.10.40 + +LMB +remote segment +where 192.168.10.40 is either the IP address of the +remote LMB or the network broadcast address of the remote segment. + + + + + + + +WINS: The Windows Internetworking Name Server + + +WINS +name_type +LanManager-compatible +Use of WINS (either Samba WINS or 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. +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. + + + +NetBIOS name length +name_type +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. Thus, all NetBIOS names are 16 characters long (including the +name_type information). + + + +WINS +registered +NetLogon service +lmhosts +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 cannot be used across network segments, this type of +information can only be provided via WINS or via a statically configured +lmhosts file that must reside on all clients in the +absence of WINS. + + + +synchronization +LMB +DMB +WINS +browse list +WINS also forces browse list synchronization by all LMBs. LMBs must synchronize their browse list with the +DMB, and WINS helps the LMB to identify its DMB. By definition this will work only within a single workgroup. +Note that the DMB has nothing to do with what is referred to as an MS Windows NT domain. The latter is a +reference to a security environment, while the DMB refers to the master controller for browse list information +only. + + + +WINS +TCP/IP protocol stack +WINS servers +name-to-address +WINS will work correctly only if every client TCP/IP protocol stack +is configured to use the WINS servers. Any client that is not +configured to use the WINS server will continue to use only broadcast-based +name registration, so 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. + + + +To configure Samba as a WINS server, just add +yes to the &smb.conf; +file [global] section. + + + +To configure Samba to register with a WINS server, just add 10.0.0.18 to your &smb.conf; file section. + + + +Never use yes together with 10.0.0.18 particularly not using its own IP address. Specifying both will cause &nmbd; +to refuse to start! + + + +WINS Server Configuration + + +WINS +Either a Samba server or a Windows NT server machine may be set up +as a WINS server. To configure a Samba server to be a WINS server, you must +add to the &smb.conf; file on the selected Server the following line to +the section: + + + + +yes + + + + +Samba 1.9.17 +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. + + + +Machines configured with yes will keep a list of +all NetBIOS names registered with them, acting as a DNS for NetBIOS names. + + + +only one WINS server +It is strongly recommended to set up only one WINS server. Do not set the yes option on more than one Samba server on a network. + + + +replicationWINS +Windows NT/200x +WINS service +replication protocols +WINS server +To configure Windows NT/200x Server as a WINS server, install and configure the WINS service. See the Windows +NT/200x documentation for details. Windows NT/200x WINS servers can replicate to each other, allowing more +than one to be set up in a complex subnet environment. Because Microsoft refuses to document the replication +protocols, Samba cannot currently participate in these replications. It is possible that a Samba-to-Samba WINS +replication protocol may be defined in the future, in which case more than one Samba machine could be set up +as a WINS server. Currently only one Samba server should have the yes parameter set. + + + +WINS server +Primary WINS Server +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 Primary WINS Server field of the Control +Panel->Network->Protocols->TCP->WINS Server dialogs in Windows 9x/Me or Windows NT/200x. To tell a +Samba server the IP address of the WINS server, add the following line to the section of all &smb.conf; files: + +<name or IP address> + +where <name or IP address> is either the DNS name of the WINS server +machine or its IP address. + + + +This line must not be set in the &smb.conf; file of the Samba +server acting as the WINS server itself. If you set both the +yes option and the +<name> option then +nmbd will fail to start. + + + +cross-subnet browsing +Windows 9x/Me +Windows NT/200x +not part of domain +There are two possible scenarios for setting up cross-subnet browsing. +The first details setting up cross-subnet browsing on a network containing +Windows 9x/Me, Samba, and Windows NT/200x 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. + + + + + +WINS Replication + + +replicationWINS +WINS replication +Samba-3 does not support native WINS replication. There was an approach to implement it, called +wrepld, but it was never ready for action and the development is now discontinued. + + +Meanwhile, there is a project named samba4WINS, which makes it possible to +run the Samba-4 WINS server parallel to Samba-3 since version 3.0.21. More information about +samba4WINS are available at http://ftp.sernet.de/pub/samba4WINS. + + + + + +Static WINS Entries + + +static WINS entries +wins.dat +/usr/local/samba/var/locks +/var/run/samba +Adding static entries to your Samba WINS server is actually fairly easy. All you have to do is add a line to +wins.dat, typically located in /usr/local/samba/var/locks or /var/run/samba. + + + +Entries in wins.dat take the form of: + +"NAME#TYPE" TTL ADDRESS+ FLAGS + +TTL +time-to-liveTTL +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. + + + +A change that has been made to the wins.dat will not take effect until &nmbd; has been +restarted. It should be noted that since the wins.dat file changes dynamically, &nmbd; +should be stopped before editting this file. Do not forget to restart &nmbd; when this file has been editted. + + + +A typical dynamic entry looks like this: + +"MADMAN#03" 1155298378 192.168.1.2 66R + +To make a NetBIOS name static (permanent), simply set the TTL to 0, like this: + +"MADMAN#03" 0 192.168.1.2 66R + + + + +NetBIOS flags +Broadcast node +Peer node +Meta node +Hybrid node +Permanent name +nameserv.h +The NetBIOS flags may be interpreted as additive hexadecimal values: 00 - Broadcast node registration, 20 - +Peer node registration, 40 - Meta node registration, 60 - Hybrid node registration, 02 - Permanent name, 04 - +Active name, 80 - Group name. The 'R' indicates this is a registration record. Thus 66R means: Hybrid node +active and permanent NetBIOS name. These values may be found in the nameserv.h header +file from the Samba source code repository. These are the values for the NB flags. + + + +WINS replication +Though this method works with early Samba-3 versions, there is a possibility that it may change in future +versions if WINS replication is added. + + + + + + +Helpful Hints + + +The following hints should be carefully considered because they are stumbling points +for many new network administrators. + + + +Windows Networking Protocols + + +browsing problems +more than one protocol +A common cause of browsing problems results from the installation of more than one protocol on an MS Windows +machine. + + + +Do not use more than one protocol on MS Windows clients. + + + +LMB +DMB +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 the most suitable machine will predictably +win and thus retain its role. + + + +NetBIOS network interface +TCP/IP +IPX +LMB +Windows 9x/Me +TCP/IP-only +The election process is fought out, so to speak over every NetBIOS network interface. In +the case of a Windows 9x/Me 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/Me 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 because Windows 9x/Me will insist it knows who the LMB is. Samba will then +cease to function as an LMB, and browse list operation on all TCP/IP-only machines will therefore fail. + + + +Windows 9x/Me +extended protocol +Windows 95, 98, 98se, and Me are referred to generically as Windows 9x/Me. The Windows NT4, 200x, and XP use +common protocols. These are roughly referred to as the Windows NT family, but it should be recognized 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. + + + +The safest rule of all to follow is: Use only one protocol! + + + + + +Name Resolution Order + + +NetBIOS names +name_type +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: + + + + WINS &smbmdash; the best tool. + LMHOSTS &smbmdash; static and hard to maintain. + Broadcast &smbmdash; uses UDP and cannot resolve names across remote segments. + + + +Alternative means of name resolution include: + + +Static /etc/hosts &smbmdash; hard to maintain and lacks name_type info. +DNS &smbmdash; is a good choice but lacks essential NetBIOS name_type information. + + + +restrict DNS +name resolve order +Many sites want to restrict DNS lookups and avoid broadcast name +resolution traffic. The name resolve order parameter is of great help here. +The syntax of the name resolve order parameter is: + +wins lmhosts bcast host + +or + +wins lmhosts (eliminates bcast and host) + +The default is: + +host lmhost wins bcast, + +gethostbyname() function call +where host refers to the native methods used by the UNIX system to implement the +gethostbyname() function call. This is normally controlled by /etc/host.conf, +/etc/nsswitch.conf and /etc/resolv.conf. + + + + + +Technical Overview of Browsing + + +SMB +SMB networking provides a mechanism by which clients can access a list +of machines in a network called . This list +contains machines that are ready to offer file and/or print services +to other machines within the network. It therefore does not include +machines that 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. + + + +NetBIOS over TCP/IP +DNS/LDAP/ADS +name resolution +MS Windows 2000 and later versions, as with Samba-3 and later versions, 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. + + + +NetBIOS +WINS +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 cannot be provided by any other means of name resolution. + + + +Browsing Support in Samba + + +browsing +LMB +domain logons +scripts +Samba facilitates browsing. The browsing is supported by &nmbd; +and is also controlled by options in the &smb.conf; file. +Samba can act as an LMB for a workgroup, and the ability +to support domain logons and scripts is now available. + + + +DMB for a workgroup +LMB +WINS +Samba can also act as a DMB for a workgroup. This +means that it will collate lists from LMBs 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. + + + +domain master +Do 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 +DMB per workgroup, regardless of whether it is NT, Samba, +or any other type of domain master that is providing this service. + + + +nmbd +WINS server +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 200x can be configured as +your WINS server. In a mixed NT/200x server and Samba environment on +a WAN, 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 the WINS server. + + + +nmbd +To get browsing to work, you need to run nmbd as usual, but must +use the option in &smb.conf; +to control what workgroup Samba becomes a part of. + + + +browsing another subnet +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 used only for unusual purposes: announcements over the +Internet, for example. See in the &smb.conf; man page. + + + + +Problem Resolution + + +log.nmbd +browse.dat +If something does not work, the log.nmbd file will help +to track down the problem. Try a of 2 or 3 for finding +problems. Also note that the current browse list usually gets stored +in text form in a file called browse.dat. + + + +\\SERVER +filemanager +If it does not work, you should still be able to +type the server name as \\SERVER in filemanager, then +press enter, and filemanager should display the list of available shares. + + + +IPC$ +guest account +Some people find browsing fails because they do not have the global + set to a valid account. Remember that the +IPC$ connection that lists the shares is done as guest and so you must have a valid guest account. + + + +IPC$ +Windows Explorer +browse resources +Network Neighborhood +My Network Places +The IPC$ share is used by all SMB/CIFS clients to obtain the list of resources that is +available on the server. This is the source of the list of shares and printers when browsing an SMB/CIFS +server (also Windows machines) using the Windows Explorer to browse resources through the Windows Network +Neighborhood (also called My Network Places) through to a Windows server. At this point, the client has opened +a connection to the \\server\IPC4 resource. Clicking on a share will then open up a +connection to the \\server\share. + + + +guest account +anonymous access +IPC$ +browse server resources +MS Windows 2000 and later (as with Samba) can be configured to disallow +anonymous (i.e., 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/Me clients are not able to do this and thus will not be able to browse +server resources. + + + +broadcast address +The other big problem people have is that their broadcast address, +netmask, or IP address is wrong (specified with the option +in &smb.conf;) + + + + +Cross-Subnet Browsing + + +replicationbrowse lists +browse across subnet +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. + + + +browse lists +broadcast traffic +UDP +WINS +remote announce +remote browse sync +To see browse lists that span TCP/IP subnets (i.e., networks separated by routers that do not pass broadcast +traffic), you must set up at least one WINS server. The WINS server acts as a DNS for NetBIOS names. This will +allow NetBIOS name-to-IP address translation to be completed by a direct query of the WINS server. This is +done via a directed UDP packet on port 137 to the WINS server machine. The WINS server avoids the necessity of +default NetBIOS name-to-IP address translation, which is done using UDP 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. The Samba hacks, remote browse sync, and remote +announce are designed to get around the natural limitations that prevent UDP broadcast +propagation. The hacks are not a universal solution and they should not be used in place of WINS, they are +considered last resort methods. + + + +DHCP +browsing across subnets +WINS +Network settings +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 Windows 9x/Me and Windows NT/200x/XP, this is in the TCP/IP Properties, under Network +settings; for Samba, this is in the &smb.conf; file. + + + +NetBIOS over TCP/IP +ADS +DNS +It is possible to operate Samba-3 without NetBIOS over TCP/IP. If you do this, be warned that if used outside +of MS ADS, this will forgo network browsing support. ADS permits network browsing support through DNS, +providing appropriate DNS records are inserted for all Samba servers. + + + +Behavior of Cross-Subnet Browsing + + +cross-subnet browsing +complicated +Cross-subnet browsing is a complicated dance, containing multiple moving parts. It has taken Microsoft several +years to get the code that correctly achieves this, and Samba lags behind in some areas. Samba is capable of +cross-subnet browsing when configured correctly. + + + +Consider a network set up as in Cross-Subnet Browsing Example. + + +
+ Cross-Subnet Browsing Example. + browsing1 +
+ + +broadcasts +DMB +WINS +This consists of three subnets (1, 2, 3) connected by two routers (R1, R2), which do not pass broadcasts. +Subnet 1 has five machines on it, subnet 2 has four machines, and subnet 3 has four machines. Assume for the +moment that all machines are configured to be in the same workgroup (for simplicity's sake). Machine N1_C on +subnet 1 is configured as the DMB (i.e., it will collate the browse lists for the workgroup). Machine N2_D is +configured as a WINS server, and all the other machines are configured to register their NetBIOS names with +it. + + + +master browsers +LMB +DMB +As these machines are booted up, elections for master browsers +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 LMBs for +their particular subnet. N1_C has an advantage in winning as the +LMB on subnet 1 because it is set up as DMB. + + + +LMB +browse list +On each of the three networks, machines that are configured to offer sharing services will broadcast that they +are offering these services. The LMB 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. + + + +LMB +authoritative +verifiable +trusted +non-authoritative +For each network, the LMB on that network is +considered authoritative for all the names it receives via +local broadcast. This is because a machine seen by the LMB +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 LMBs learn about when collating their +browse lists have not been directly seen. These records are +called non-authoritative. + + + +network neighborhood +At this point the browse lists appear as shown in Browse Subnet Example 1 +(these are the machines you would see in your network neighborhood if you looked in it on a particular network +right now). + + + + + Browse Subnet Example 1 + + + SubnetBrowse MasterList + + + + Subnet1N1_CN1_A, N1_B, N1_C, N1_D, N1_E + Subnet2N2_BN2_A, N2_B, N2_C, N2_D + Subnet3N3_DN3_A, N3_B, N3_C, N3_D + + +
+ + + +At this point all the subnets are separate, and no machine is seen across any of the subnets. + + + +DMB +LMB +synchronize +WINS +Now examine subnet 2 in Browse Subnet Example 2. As soon as N2_B has become the +LMB, it looks for a DMB with which to synchronize its browse list. 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 DMB (N1_C) with the WINS server as soon as it was started. + + + +MasterAnnouncement +NetServerEnum2 +synchronization +browse lists +Once N2_B knows the address of the DMB, it tells it that is the LMB 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 DMB to send it all the server names it knows +about. Once the DMB receives the MasterAnnouncement packet, it schedules a +synchronization request to the sender of that packet. After both synchronizations are complete, the browse +lists look like those in Browse Subnet Example 2 + + + + Browse Subnet Example 2 + + + + + + SubnetBrowse MasterList + + + + Subnet1N1_CN1_A, N1_B, N1_C, N1_D, N1_E, +N2_A(*), N2_B(*), N2_C(*), N2_D(*) + Subnet2N2_BN2_A, N2_B, N2_C, N2_D, N1_A(*), +N1_B(*), N1_C(*), N1_D(*), N1_E(*) + Subnet3N3_DN3_A, N3_B, N3_C, N3_D + + +
+ + +non-authoritative +Servers with an (*) after them are non-authoritative names. + + + +Network Neighborhood +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 see only the servers on their own subnet. + + + +DMB +The same sequence of events that occurred for N2_B now occurs for the LMB on subnet 3 (N3_D). When it +synchronizes browse lists with the DMB (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 will appear as shown in Browse Subnet Example 3 + + + + Browse Subnet Example 3 + + + + + + + SubnetBrowse MasterList + + + + Subnet1N1_CN1_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(*) + Subnet2N2_BN2_A, N2_B, N2_C, N2_D, N1_A(*), +N1_B(*), N1_C(*), N1_D(*), N1_E(*) + Subnet3N3_DN3_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(*) + + +
+ + +Servers with an (*) after them are non-authoritative names. + + + +At this point, users looking in their Network Neighborhood on +subnets 1 or 3 will see all the servers on all subnets, while users on +subnet 2 will still see only the servers on subnets 1 and 2, but not 3. + + + +LMB +DMB +browse lists +Finally, the LMB for subnet 2 (N2_B) will sync again +with the DMB (N1_C) and will receive the missing +server entries. Finally, as when a steady state (if no machines +are removed or shut off) has been achieved, the browse lists will appear +as shown in Browse Subnet Example 4. + + + + Browse Subnet Example 4 + + + + + + + SubnetBrowse MasterList + + + + Subnet1N1_CN1_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(*) + Subnet2N2_BN2_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(*) + Subnet3N3_DN3_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(*) + + +
+ + +Servers with an (*) after them are non-authoritative names. + + + +Synchronizations between the DMB and LMBs +will continue to occur, but this should remain a +steady-state operation. + + + +If either router R1 or R2 fails, the following will occur: + + + + + +Network Neighborhood + Names of computers on each side of the inaccessible network fragments + will be maintained for as long as 36 minutes in the Network Neighborhood + lists. + + + + + + Attempts to connect to these inaccessible computers will fail, but the + names will not be removed from the Network Neighborhood lists. + + + + + +WINS +NetBIOS name resolution +DNS server + If one of the fragments is cut off from the WINS server, it will only + be able to access servers on its local subnet using subnet-isolated + broadcast NetBIOS name resolution. The effect is similar to that of + losing access to a DNS server. + + + + + + + + +Common Errors + + +browsing problems +name resolution +Many questions are asked on the mailing lists regarding browsing. The majority of browsing +problems originate from incorrect configuration of NetBIOS name resolution. Some are of +particular note. + + + +Flushing the Samba NetBIOS Name Cache + + +How Can One Flush the Samba NetBIOS Name Cache without Restarting Samba? + + + +flush name cache +nmbd +NetBIOS name cache +rogue machine +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. This does not make certain that a rogue machine name will not reappear +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, every machine on the network must be +shut down and restarted 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 (perhaps months). + + + + + + Server Resources Cannot Be Listed + +My Client Reports "This server is not configured to list shared resources." + + + +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. + + +Also see in the &smb.conf; man page. + + + + + I Get an "<errorname>Unable to browse the network</errorname>" Error + + This error can have multiple causes: +browsing problems + + + + There is no LMB. Configure &nmbd; + or any other machine to serve as LMB. + You cannot log onto the machine that is the LMB. + Can you log on to it as a guest user? + There is no IP connectivity to the LMB. + Can you reach it by broadcast? + + + + +Browsing of Shares and Directories is Very Slow + + +slow browsing +There are only two machines on a test network. One is a Samba server, the other a Windows XP machine. +Authentication and logons work perfectly, but when I try to explore shares on the Samba server, the +Windows XP client becomes unresponsive. Sometimes it does not respond for some minutes. Eventually, +Windows Explorer will respond and displays files and directories without problem. + + + + +cmd +But, the share is immediately available from a command shell (cmd, followed by +exploration with DOS command. Is this a Samba problem, or is it a Windows problem? How can I solve this? + + + +Here are a few possibilities: + + + + + Bad Networking Hardware + +bad hardware +WebClient +defective hardware +Bad networking hardware +data corruption + Most common defective hardware problems center around low cost or defective hubs, routers, + network interface controllers (NICs), and bad wiring. If one piece of hardware is defective, + the whole network may suffer. Bad networking hardware can cause data corruption. Most bad + networking hardware problems are accompanied by an increase in apparent network traffic, + but not all. + + + + + The Windows XP WebClient + +network browsing problems + A number of sites have reported similar slow network browsing problems and found that when + the WebClient service is turned off, the problem disappears. This is certainly something + that should be explored because it is a simple solution &smbmdash; if it works. + + + + + Inconsistent WINS Configuration + +WINS Configuration +WINS server + This type of problem is common when one client is configured to use a WINS server (that is + a TCP/IP configuration setting) and there is no WINS server on the network. Alternatively, + this will happen if there is a WINS server and Samba is not configured to use it. The use of + WINS is highly recommended if the network is using NetBIOS over TCP/IP protocols. If use + of NetBIOS over TCP/IP is disabled on all clients, Samba should not be configured as a WINS + server, nor should it be configured to use one. + + + + + Incorrect DNS Configuration + +DNS Configuration +NetBIOS over TCP/IP disabled + If use of NetBIOS over TCP/IP is disabled, Active Directory is in use and the DNS server + has been incorrectly configured. For further information refer to + DNS and Active Directory. + + + + + + +Invalid Cached Share References Affects Network Browsing + +cached references +stale network links +Cached references on your MS Windows client (workstation or server) to shares or servers that no longer exist +can cause MS Windows Explorer to appear unresponsive as it tries to connect to these shares. After a delay +(can take a long time) it times out and browsing will appear to be mostly normal again. + + + +To eliminate the problem the stale cached references should be removed. This does not happen automatically and +requires manual intervention. This is a design feature of MS Windows and not anything that Samba can change. +To remove the stale shortcuts found in My Network Places which refer to what are now +invalid shares or servers it is necessary to edit the Windows Registry under +HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\. Edit the entry +MountPoints2 (on Windows XP and later, or MountPoints on Windows 2000 +and earlier). Remove all keys named \\server\share (where 'server' and 'share' refer to a +non-existent server or share). + + + +Removal of stale network links needs to be done on a per-user basis. Alternately, you can delete the +shortcuts from the MS Windows Explorer in My Network Places just by right-clicking them and +selecting Delete. + + + +slow network browsing +Samba users have reported that these stale references negatively affect network browsing with Windows, Samba, +and Novell servers. It is suspected to be a universal problem not directly related to the Samba +server. Samba users may experience this more often due to Samba being somewhat viewed as an experimenter's +toolkit. This results from the fact that a user might go through several reconfigurations and incarnations of +their Samba server, by different names, with different shares, increasing the chances for having stale +(invalid) cached share references. Windows clients do not expire these references thus necessitating manual +removal. + + + +It is common for Open dialog boxes (for example; in Word and Excel) to respond very +slowly, as they attempt to locate all of the cached references, even if they are not in the current directory +being accessed. + + + + -- cgit