View your network neighbors (1)

I. Working principle of network neighbors
The Network Neighbor uses the NetBIOS protocol. In the Win98 Second Edition system, you can install the NetBIOS protocol as long as the TCP/IP protocol is installed, because "enable NetBIOS through TCP/IP" is enabled by default. Netbois (basic network input/output system) was initially developed by IBM and sytek as an API to enable user software to use LAN resources. Since its birth, netbois has become one of many other network applications. Program . Strictly speaking, NetBIOS is the interface standard for accessing network services.
NetBIOS was originally designed as the network controller for the ibm lan and is a software layer that uses specific hardware to connect to the network operating system. NetBIOS is extended and allows the program to use the NetBIOS interface to operate the IBM licensing ring structure. NetBIOS has been recognized as an industrial standard. Generally, refer to NetBIOS-compatible LANs.
It provides a set of methods for network programs to communicate with each other and transmit data. Basically, NetBIOS allows programs and network sessions. It aims to separate the program from any type of hardware property. It also frees software developers from the following responsibilities: network error fixing, low-layer information addressing, and routing. Using the NetBIOS interface, you can do a lot of work for software developers. NetBIOS standardizes interfaces between program and LAN operation capabilities. With them, you can refine the program to which layer of the OSI model is written, so that the program can be transplanted to other networks. In the NetBIOS LAN environment, the computer name is known by the system. Each computer in the network has a permanent name compiled using different methods. These names will be further discussed below.
By using NetBIOS datagram or broadcast, a PC on the NetBIOS LAN establishes a session to communicate with each other. Sessions allow more information to be transmitted, detected, and corrected. Communication is based on one-to-one communication. The datagram or broadcast mode allows one computer to communicate with multiple other computers at the same time, but the information size is limited. No errors are detected or corrected using the datagram or broadcast method. However, you do not need to establish a session for datagram communication.
In this environment, all communication is submitted to NetBIOS in a format called "Network Control Block. The allocation of these blocks in the memory depends on the user program. These "network control blocks" are allocated to the domain and reserved for input and output respectively. In today's environments, NetBIOS is a common protocol. Ethernet, licensing ring, and ibm pc network support NetBIOS. In its original version, it serves only as an interface for programs and network adapters. Since then, the transfer function has been added to NetBIOS, increasing its functionality.
In NETBIOS, connection-oriented (TCP) and non-connection (UDP) communication are supported. It supports broadcast and replay, and supports three separate services: naming, session, and datagram.
NetBIOS name is used to identify resources on the network. The program starts and ends the session with these names. You can use multiple programs to configure a separate machine. Each program has a unique NetBIOS name. Each pc supporting applications also has a user-defined or internal NetBIOS site name. NetBIOS can contain up to 16 alpha letters. In the entire resource routing network, the combination of letters must be unique. Before a PC using NetBIOS can fully work on the network, the PC must first register the NetBIOS name. Take a closer look at the following. Start a machine ~~ What is he doing ?? When Client A is active, client a broadcasts its name. When it successfully broadcasts itself, and no one else has the same name as it, the client registers successfully. The registration process is as follows: 1. on login, client a broadcasts its own and its NetBIOS information 6 to 10 times in all places (depending on this method, which the who wants to come up ....), Make sure that other network members receive the message. (If a machine does not receive the message, the client a in the network neighbor of the machine will be invisible.) 2. if another client uses this name, another client B publishes its own broadcast, including the name it is using. Client A requesting login to stop all registration attempts. 3. If no other client is opposed to registration, client a requesting login completes the registration process. If a name server is available, the name server will be recorded in its database. The name of a server is a and the IP address is XXX. xxx. xxx. xxx 4. When host a is shut down normally, broadcast again to release the name just registered. After receiving the name, the computer on the same network segment will put it in the network neighbor and the sesame oil. (Rely on, fainted and shut down normally ..... Abnormal? Don't worry.) If there is a WINS server on the Internet, the name will be canceled after the client shuts down abnormally for a certain period of time. If the sesame oil WINS service is used, you can run it on the icon in the network neighbor ~~, Be careful. At this time, the query name must be broadcast ~~, If you have dozens of machines on the internet, broadcast N Articles, and wait for a response. Is the problem solved? You need to know that broadcast packets are prone to problems, especially in networks with a large number of machines. This is one of the reasons why Network peers often cannot find people, and broadcast packets cannot pass through the routing, therefore, machines of different subnets are invisible in the network neighbors. (If a WINS server exists and the node type is not B, it will be a little better. It will not be broadcast. For details, refer to the relevant information about the WINS node type ). In fact, even if some machines do not receive a registration request, that is, they cannot be seen in the network neighbors. As long as a is not exactly the same as B, it would be better if there is a WINS service, it doesn't matter if you have the same name with him. wins will update the record or refuse a to register the name. When you try to communicate with host a Based on NETBIOS, such as passing only files, you will first query the NetBIOS Name and start communication if you find it. There are two types of names in the NetBIOS environment: unique and set. The unique name must be unique in the network. The Set Name does not have to be unique in the network. All processes with the same name belong to the same set. Each NetBIOS node contains a table with the current name of the node. NetBIOS names can contain 16 letters. Microsoft only allows 15 letters to be used in the NetBIOS name, and the third letter is the NetBIOS suffix. The NetBIOS suffix is used in Microsoft networking software to differentiate the features of installation and the registered devices and services. [Note: SMB and NBT (NetBIOS on TCP/IP) work closely together and both use port 137,138,139. Port 137 is the NetBIOS name UDP, port 138 is the NetBIOS datagram UDP, and port 139 is the NetBIOS session TCP] Hey hey, I have never heard of this port number for security knowledge, if you want to connect your network to the nearest neighbor, you still need to consider security ~~
1. browsing list when you browse the network neighbors, you should be able to see the list of machines in the working group where the local machine is located, or enter the net view command at the command prompt to get the list of working groups where the local machine is located, A working group is actually a group of computers that share the browsing list. Computers in the same network segment belong to the same working group by default. Browsing list: on the Microsoft Network, you can view the entire network in the browsing list? Subnet or broadcast domain? You can consider) All computers. When you open the entire network through the network neighbor window, you will see a list of working groups, and then open a Working Group, you will see the computer list in it (you can also use the net view/domain: workgroupname command in DOS mode). This is what we call the browsing list. Working groups are essentially a group of computers that share a browsing list. All working groups are peer-to-peer and there is no rule that all computers cannot be in the same working group. The browser list is provided by the browser master server through broadcast query. The browser master server is one of the most important computers in the Working Group. It maintains the browsing list in this Working Group and the list of Master servers designated for other working groups, provides browsing services for other computers in the Working Group and other computers visiting the Working Group. Each working group selects a browser master server for each transmission protocol, most of the network browsing failures we often encounter are caused by the absence of the master server in your working group. You can use the nbtstat-A computername command in a working group to find the browser master server using the NBT Protocol. Its identifier is \ _ msbrowse _ name segment. By default, the browser master server in the Win98 workgroup is the first computer in the workgroup to enable file and printer sharing, you can also manually configure a Win98 computer as the browser master server (the method will be described later in the network configuration section, but the performance will be affected because the browser master server needs to maintain the Dynamic Browsing list ), if multiple computers in a working group have configured this option, or the current browser master server has disabled the system, and no other computer has enabled the master control settings, the master browser should be elected. The process of the browser's election message is very simple. First, a computer sends an election critical message, which contains information from the computer (operating system, version, NetBIOS name, and so on ), the election message is broadcast to the network. Each computer in the Working Group compares its own information with the election message for priority, which is mainly used by the operating system, I remember it was NT Server> NT Workstation> Win98> wfwg. In the end, it was the best browser master server.
2. the browsing list of the main browser is actually obtained from a computer in the Working Group (this computer is generally called the main browser). In a working group, only one computer acts as the main browser, one or two computers act as backup browsers. If this parameter is not specified, the identity of the master browser and backup browser is obtained randomly by the computer on the network. If all the machines on the network are Win98, then, the first computer that opens and enables file and print sharing serves as the main browser. If the main browser shuts down, it is necessary to elect the main browser. When a computer enters the network, it will broadcast its own existence through the network broadcast (you need to bind files and print shares on the relevant Protocols ), after receiving the broadcast, the main browser saves the computer information to its existing list. In addition to saving the computer list of the working group, the main browser also saves the list of computers of other working groups in the same network segment, so that the computers of this Working Group can browse the computers of other working groups.
3. In order to help users find network resources, Microsoft uses a mechanism called "Browser Service" to find and locate network resources. In a peer network, when the number of hosts is more than a certain number, sometimes we open "Network neighbors", the speed will be very slow, (especially in a hybrid environment of 2000 and 98) It is not a fault. The working mechanism of "Network neighbors" determines this fact. When our machines start, first, we will look for a machine in the network-the main browser, and then report that he exists in the network. The main browser implements this function by maintaining a "Browse table. A list of available netblos-based resources is maintained in the main browsing table. The ing between netblos names and IP addresses includes information of all our machines. The common client adds himself to the main browser's main browser table and tells him: "I came to this network." My netbilos name is computer1, And the IP address is 192.168.0.1. When you open the network neighbor, first, find "Main Browser" through broadcast ". If no "Main Browser" is available or the main browser is shut down, a "Main Browser" will be selected through "election" on the network. The election principles include: 1 Operating System 2 operating system version 3 computer role (note: this process may be slow !! Especially in a 2000 98 hybrid environment) after finding the master browser, you can get a list of backup browsers from the master browser, then, you can obtain all the lists from the backup browser (the backup of the main browser when backing up the browser stores copies of browsing tables). In this case, all the computers will appear in the network neighbors! The customer's browsing process is as follows: 1. Add the server to the browser list by publishing an announcement to the main browser. 2. The list of shared servers (domains) between the master browser and backup browser. 3. The client retrieves the computer list of the backup browser from the main browser. 4. Contact the backup browser to retrieve the server list. 5. The client and server contact to retrieve the list of shared resources on the server. In order to effectively locate network resources on the network, the Microsoft Windows Web Browser Service must have a specific "Browser Server" to participate and provide. Browser Server roles include "(domain) Main Browser Server", "backup Browser Server", and "potential Browser Server. Browsing servers are generally started by the first computers and can be automatically changed or handed over by election. Every 15 minutes, the primary browser of each subnet declares itself to other primary browsers on the subnetwork. Every 12 minutes, the main browser of each domain contacts wins to obtain a list of all domainname <1B> domains. Every 12 minutes, each primary browser (subnet) contacts the domain primary browser to update the browser table. Every 12 minutes, each backup browser contacts its local master browser to retrieve and update the browsing table. All computers with server components (that is, those with the ability to share network resources) declare themselves to the main browser in their local domain. Browser election occurs when the local subnet cannot find the primary browser or the domain controller is initialized. The election is determined by the operating system version number and identity. In addition, most of the traffic in this process is broadcast traffic. This is why wins is required for normal use of "Network neighbors" in Multi-subnet environments ". This is also why we strongly recommend that you use "Network neighbors" as few as possible in the enterprise network ". Its working process determines that in a relatively large and dynamically changing network, it is doomed to be unreliable, there are many problems, and bring chaos. The whole network browsing process: When a Win98 enters the network, if it carries a Server Service (file and printer sharing are enabled), it will broadcast its existence to the network, the browser master server obtains this declaration and puts it in the browser list maintained by itself. The computer that does not bind the file and printer share on the corresponding protocol will not be declared, so it will not appear in the network neighbors. When the customer's computer wants to obtain the desired list of network resources, it first broadcasts a browser request. After the browser master server receives the request, if the requested list is the browsing list of this group, directly send back the list of resources required by the customer. If you are requesting a list of other working groups, the browser master server will find the corresponding Working Group's browser based on the records in the browsing list and return it to the user, you can get the desired browsing list from there.
4. the relationship between network neighbors and services: first, describe the structure of network neighbors in Windows: computer Browser Service Server Service Workstation Service Microsoft network file and printer sharing protocol Microsoft network client these services and protocols constitute the Microsoft browser service that our users can access, that is to say, to ensure that the network neighbor can work normally, the system must first work properly as mentioned above. The key points of these services: The Computer Browser Service is the head of the system, and the server service is the right hand of the Computer Browser Service. It is mainly responsible for providing support for file sharing and printer sharing, file and printer sharing in Microsoft networks is a reflection of the server service on the NIC. The Workstation Service is the left hand of the Computer Browser Service. It is mainly responsible for receiving the browsing list. The Microsoft Network Client is the reflection of the workstation service on the NIC.