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diff --git a/docs/textdocs/NetBIOS.txt b/docs/textdocs/NetBIOS.txt new file mode 100644 index 0000000000..ca0dcc84b7 --- /dev/null +++ b/docs/textdocs/NetBIOS.txt @@ -0,0 +1,152 @@ +Contributor: lkcl - samba@samba.org + Copyright 1997 Luke Kenneth Casson Leighton +Date: March 1997 +Status: Current +Updated: 12jun97 + +Subject: Definition of NetBIOS Protocol and Name Resolution Modes +============================================================================= + +======= +NETBIOS +======= + +NetBIOS runs over the following tranports: TCP/IP; NetBEUI and IPX/SPX. +Samba only uses NetBIOS over TCP/IP. For details on the TCP/IP NetBIOS +Session Service NetBIOS Datagram Service, and NetBIOS Names, see +rfc1001.txt and rfc1002.txt. + +NetBEUI is a raw NetBIOS frame protocol implementation that allows NetBIOS +datagrams to be sent out over the 'wire' embedded within LLC frames. +NetBEUI is not required when using NetBIOS over TCP/IP protocols and it +is preferable NOT to install NetBEUI if it can be avoided. + +IPX/SPX is also not required when using NetBIOS over TCP/IP, and it is +preferable NOT to install the IPX/SPX transport unless you are using Novell +servers. At the very least, it is recommended that you do not install +'NetBIOS over IPX/SPX'. + +[When installing Windows 95, you will find that NetBEUI and IPX/SPX are +installed as the default protocols. This is because they are the simplest +to manage: no Windows 95 user-configuration is required]. + + +NetBIOS applications (such as samba) offer their services (for example, +SMB file and print sharing) on a NetBIOS name. They must claim this name +on the network before doing so. The NetBIOS session service will then +accept connections on the application's behalf (on the NetBIOS name +claimed by the application). A NetBIOS session between the application +and the client can then commence. + +NetBIOS names consist of 15 characters plus a 'type' character. This is +similar, in concept, to an IP address and a TCP port number, respectively. +A NetBIOS-aware application on a host will offer different services under +different NetBIOS name types, just as a host will offer different TCP/IP +services on different port numbers. + +NetBIOS names must be claimed on a network, and must be defended. The use +of NetBIOS names is most suitable on a single subnet; a Local Area Network +or a Wide Area Network. + +NetBIOS names are either UNIQUE or GROUP. Only one application can claim a +UNIQUE NetBIOS name on a network. + +There are two kinds of NetBIOS Name resolution: Broadcast and Point-to-Point. + + +================= +BROADCAST NetBIOS +================= + +Clients can claim names, and therefore offer services on successfully claimed +names, on their broadcast-isolated subnet. One way to get NetBIOS services +(such as browsing: see ftp.microsoft.com/drg/developr/CIFS/browdiff.txt; and +SMB file/print sharing: see cifs4.txt) working on a LAN or WAN is to make +your routers forward all broadcast packets from TCP/IP ports 137, 138 and 139. + +This, however, is not recommended. If you have a large LAN or WAN, you will +find that some of your hosts spend 95 percent of their time dealing with +broadcast traffic. [If you have IPX/SPX on your LAN or WAN, you will find +that this is already happening: a packet analyzer will show, roughly +every twelve minutes, great swathes of broadcast traffic!]. + + +============ +NBNS NetBIOS +============ + +rfc1001.txt describes, amongst other things, the implementation and use +of, a 'NetBIOS Name Service'. NT/AS offers 'Windows Internet Name Service' +which is fully rfc1001/2 compliant, but has had to take specific action +with certain NetBIOS names in order to make it useful. (for example, it +deals with the registration of <1c> <1d> <1e> names all in different ways. +I recommend the reading of the Microsoft WINS Server Help files for full +details). + +Samba also offers WINS server capabilities. Samba does not interact +with NT/AS (WINS replication), so if you have a mixed NT server and +Samba server environment, it is recommended that you use the NT server's +WINS capabilities, instead of samba's WINS server capabilities. + +The use of a WINS server cuts down on broadcast network traffic for +NetBIOS name resolution. It has the effect of pulling all the broadcast +isolated subnets together into a single NetBIOS scope, across your LAN +or WAN, while avoiding the use of TCP/IP broadcast packets. + +When you have a WINS server on your LAN, WINS clients will be able to +contact the WINS server to resolve NetBIOS names. Note that only those +WINS clients that have registered with the same WINS server will be +visible. The WINS server _can_ have static NetBIOS entries added to its +database (usually for security reasons you might want to consider putting +your domain controllers or other important servers as static entries, +but you should not rely on this as your sole means of security), but for +the most part, NetBIOS names are registered dynamically. + +[It is important to mention that samba's browsing capabilities (as a WINS +client) must have access to a WINS server. if you are using samba also +as a WINS server, then it will have a direct short-cut into the WINS +database. + +This provides some confusion for lots of people, and is worth mentioning +here: a Browse Server is NOT a WINS Server, even if these services are +implemented in the same application. A Browse Server _needs_ a WINS server +because a Browse Server is a WINS client, which is _not_ the same thing]. + +Clients can claim names, and therefore offer services on successfully claimed +names, on their broadcast-isolated subnet. One way to get NetBIOS services +(such as browsing: see ftp.microsoft.com/drg/developr/CIFS/browdiff.txt; and +SMB file/print sharing: see cifs6.txt) working on a LAN or WAN is to make +your routers forward all broadcast packets from TCP/IP ports 137, 138 and 139. +You will find, however, if you do this on a large LAN or a WAN, that your +network is completely swamped by NetBIOS and browsing packets, which is why +WINS was developed to minimise the necessity of broadcast traffic. + +WINS Clients therefore claim names from the WINS server. If the WINS +server allows them to register a name, the client's NetBIOS session service +can then offer services on this name. Other WINS clients will then +contact the WINS server to resolve a NetBIOS name. + + +======================= +Samba WINS Capabilities +======================= + +To configure samba as a WINS server, you must add "wins support = yes" to +the [global] section of your smb.conf file. This will enable WINS server +capabilities in nmbd. + +To configure samba as a WINS client, you must add "wins server = x.x.x.x" +to the [global] section of your smb.conf file, where x.x.x.x is the TCP/IP +address of your WINS server. The browsing capabilities in nmbd will then +register (and resolve) WAN-wide NetBIOS names with this WINS server. + +Note that if samba has "wins support = yes", then the browsing capabilities +will _not_ use the "wins server" option to resolve NetBIOS names: it will +go directly to the internal WINS database for NetBIOS name resolution. It +is therefore invalid to have both "wins support = yes" and +"wins server = x.x.x.x". Note, in particular, that if you configure the +"wins server" parameter to be the ip address of your samba server itself +(as might one intuitively think), that you will run into difficulties. +Do not use both parameters! + + |