In the development of personal computers and local area network early, in order to achieve network capacity of personal computers, Microsoft and IBM co-developed a protocol NetBIOS, which is a call interface for network communications, IBM developers as they consider this agreement BIOS designed as a basic computer network access interface, the use of the NetBIOS name. The NetBIOS interface development on the use of Microsoft Web servers and corresponding client software.
And IBM Token Ring and Ethernet on the direct implementation of the NetBIOS driver realized the NetBIOS and the physical network layer in between the specific interface, these programs follow the standards known as NetBEUI. NetBEUI direct control of the Token Ring and Ethernet drivers, so it can only run in the local area network. However, the lower NetBIOS itself did not limit the use of the protocol, so it only can run under the NetBEUI support, but also can run in the other protocol support. Other web developers in some other basis of the agreement also achieved NetBIOS interface, such as TCP / IP, IPX and Decnet so. Including the use of NetBIOS over IP TCP / IP protocol, thus the lower the compatibility with the Unix computer, a Unix and PC systems based on communication.
Windows family of computers does not necessarily use IP as its network transport protocol, it can also make use of IPX or NetBEUI protocol, but FreeBSD does not support IPX or NetBEUI on NetBIOS, must configure IP protocol for the Windows clients can share with each other FreeBSD resources.
NetBIOS name resolution
As a matter of fact is a NetBIOS and TCP / IP standards developed independently, although it can use TCP / IP as the transport protocol, but due to the different concept, it does not use TCP / IP to provide the full capacity, but to use their own way to accomplish similar work. The biggest difference is the way name resolution, NetBIOS name resolution with its own independent concepts and capabilities, so it uses the name resolution mode on and the TCP / IP in the standard analytical methods 鈹?鈹?DNS different. In the NetBIOS name resolution must be received one named after the corresponding IP address, NetBIOS sessions can be established on the basis of normal TCP connection was. Therefore, NetBIOS, the NetBIOS name resolution is a conversation with ordinary TCP connection biggest difference.
NetBIOS name resolution and DNS name resolution of NetBIOS is the biggest difference is that dynamic, the computer must first register their names before they can resolve to the name. Although dynamic analysis brought great convenience, but more complex and inefficient, so only for small-scale local area network.
Each NetBIOS name can be up to 16 characters, 16 characters Enter the name used to identify the type of procedure used. When the NetBIOS computer to communicate, it must be based on NetBIOS names, not based on IP address. A NetBIOS service program must first register their NetBIOS name, and an application will need to NetBIOS name queries needed. For example, after each Windows computer starts initializing the network configuration when using the computer name used to initialize its NetBIOS name.
NetBIOS name resolution method
From the NetBIOS name to find the corresponding node address (TCP / IP protocol for the IP address) to find several different ways.
Local Radio: send broadcast on the local network, by broadcasting the NetBIOS name of a device, find the corresponding IP address. Broadcast can be used to register their NetBIOS name, such as a computer can broadcast the name of the machine, declared itself to other computers using the NetBIOS name.
Buffer: Each NetBIOS computer support, maintenance of a NetBIOS name and IP address of the corresponding list of the names of all of these correspond to a certain degree of survival in order to update.
NetBIOS name server: use a name server to provide the name and IP resolution between the tasks, the NetBIOS name server known as the NBNS (NetBIOS Name Server), Miscrosoft achieved NBNS name server for the WINS (Windows Internet Name Service). NBN S NetBIOS computer must first register their NetBIOS name, complete name of the registration process.
Predefined file lmhosts: Microsoft Windows through the Find a local file lmhos ts stored in the data, to identify the network name and IP NetBIOS relationship, this approach is not a NetBIOS name recognition of standards, but it is Microsoft's implementation approach, and therefore a kind of de facto standard.
Resolve through DNS and the hosts file: DNS server and the local hosts file, stored data is used for standard TCP / IP protocol used to convert between names and IP the way, but with no other way to find the corresponding node address, Microsft Window s are usually also through the standard TCP / IP name resolution methods, to name and IP conversion. This is not the same NetBIOS standard, but the expansion of Micorsoft.
NetBIOS means of identification from five, and one of the names registered with different methods in conducting the different combinations, different names on the form recognition strategy. In the NetBIOS standard, will identify strategies to use different model names as different NetBIOS node type.
B-node: the way through the broadcast to register and identify NetBIOS names. The IP protocol on the Net BIOS, need to be based on UDP broadcast this way in a small network works well, but when the network increases, will be using a router to a large network is divided into several smaller networks. In general, routers do not forward broadcast data, broadcast packets sent to the local network only. Although you can configure the router to b-node broadcast forwarding UDP broadcasts, but it will produce large amounts of useless network data, and name registration and resolution of the difficulty has increased. Therefore, for larger networks, this approach undesirable.
P-node (peer-to-peer): identification of the name, etc. can provide a very effective method, which uses the NetBIOS name server for name registration and name recognition. So for each NetBIOS computer, you must specify the same NBNS server's IP address. In this way NBNS server is down or change the settings (such as IP addresses, etc.) of the case, name resolution can not be completed, it can not be NetBIOS communication. Of course, the computer can be configured to use NetBIOS over NBNS server to a problem in which the use of backup servers.
M-node (Mixed): In order to properly resolve NetBIOS names, the best combined use of broadcast and the way the name of the server, so the name recognition is a complex process. M-node first by way of B-node broadcasts the name of the recognition process, when the broadcast failed, another way to use P-node query.
H-Node (Hybrid): H-node model is a complex pattern, with M-node difference is to find a different order. H-node first find the NBNS name server, and then use the broadcast query.
Windows in the way of actual use of the name recognition is a standard H-node mode of expansion, Windows family of computers will first check the contents of the cache, and then view the WINS server, after the broadcast, and then find the lmhosts file, and by hosts and DNS lookups. Actual NetBIOS recognition is a complex process, mainly because NetBIOS name resolution is a dynamic way, each computer must register itself.
NetBIOS name of the recognition process
With different DNS, NetBIOS names using dynamic approach to management. DNS data is static, add and remove DNS names require the administrator manually change the configuration file. But the NetBIOS requires a computer on the network automatically register its name, the computer shut down after the occupation of the name will be released, this process does not require administrator intervention. Because it requires additional network data to complete the registration process name, making it unsuitable for large networks such as the Internet. NetBIOS name recognition requires three steps:
Name registration: NetBIOS startup in the computer to occupy the entire network, a NetBIOS name statement, if you have other computers take up the name, the computer will receive an error message. Registration is through the network broadcast a statement to the NetBIOS name server information or to register a way to achieve.
Name Resolution: NetBIOS names by broadcast or query to resolve a NetBIOS name server. In addition, through the lmhosts file and secondary DNS name resolution.
Name deleted: in the system shutdown or provide services to the end of the workstation will remove its occupation of the NetBIOS name.
By NetBIOS name and share name of the directory, we can locate resources on the Windows computer. Microsoft to use U NC to determine the form of a network resource location, a UNC start a double backslash, followed by the provision of resources NetBIOS computer name, then the computer resources of the shared name, the next is the following directory and file name. Such as: \ ntserversharefiles, so use a command of resources:
C:> net use f: \ ntservershare
C:> f:
F:>
Above the net use command will ntserver the share of resources mapped to F: drive.
Name server works
Because b-node broadcast on the network will produce large amounts of information flow, especially in the network is composed of multiple subnets when the router was originally used to isolate broadcast information, but in order for name resolution, you have to forward b- node broadcast packets, which fail to reduce unwanted network traffic purposes.
Using the name server for resolution can avoid this problem, customer inquiries through the pair of name servers instead of broadcasting, information flow would not have spread to every subnet, we can reduce the broadcast data, reduce network of Fudan conserve bandwidth, and effectively improve name resolution speed and accuracy.
Actually existing Windows network or even rarely use the name server for name resolution, which makes these networks there is a big name resolution problems, often there are different neighbor list of different computer networks, the fundamental reason is that broadcast is not guaranteed, it is required to way to resolve the name of the server name resolution problem.
Common NetBIOS computer and NBNS server to communicate with four different communication process:
Name Registration: Each NetBIOS computer starts, all in the name server registration. This automatically updates the database maintained and updated with the dynamic characteristics. Name server will return confirmation message and the name of the survival of TTL. If the customer's name has been taken up, the server will check whether the occupation is still the name of the client on the network to determine whether the name can be used again. This occurred mainly after the crash in the Windows computer to re-register process, because at this point in the computer crashed before it in the name server registered in the name exists, if the name server refused to provide a simple name, then the computer can not re- get their names. Only in true conflict situation, the customer name registration will fail.
Name Update: As each name there is a survival TTL, then when the experienced half of the TTL time, the customer update request to the server, refresh the TTL setting on the server.
Name Release: Customers will communicate with the server shut down the release of its occupation of the NetBIOS name, the name will make the server timeout TTL release the name.
Name Recognition: Customers can send a query to the NBNS name server request for name resolution.
In some cases, clients do not support the name server settings, or use the client software does not support the name server for resolution, you can set up a WINS proxy, which will come in the broadcast data and query the name server to convert, it can help customers Register and respond to customer inquiries broadcasting.
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