Query result 2: Netcom in Changzhi City, Shanxi Province
Query result 3: Netcom, Changzhi City, Shanxi Province
First, the concept of IP address
As we know, the Internet is a general term for communication networks composed of computers all over the world. When two computers connected to the network communicate with each other, the data packets they send will contain some additional information, that is, the address of the computer that sent the data and the address of the computer that received the data. In this way, in order to facilitate communication, people assigned each computer an identification address similar to the telephone number in our daily life in advance, which is the IP address we will introduce today. According to TCP/IP protocol, IP address is composed of 32-bit binary numbers, which is unique within the scope of the Internet. For example, the IP address of a computer connected to the Internet is:
1 10 100 10 0 100 100 1 1000 1 100 000000 10
Obviously, these figures are not easy to remember. For the convenience of memory, people divide the 32-bit binary that constitutes the IP address of a computer into four segments, each segment has 8 bits, separated by decimal points, and then convert every 8-bit binary into decimal numbers, so that the IP address of the computer above becomes: 2 10.73. 140.2.
Second, the classification of IP addresses.
As we said, the Internet is a huge internet, which connects countless networks all over the world, and the computers in each network are uniquely identified by their own IP addresses. Based on this, we can also imagine that in the huge internet, each network also has its own identifier. This is very similar to the telephone number in our daily life. For example, there is a telephone number 05 15 163. The first four digits of this number indicate which area the phone belongs to, and the following digits indicate a phone number in this area. Similar to the above example, we divide the IP address of the computer into two parts, namely the network identification and the host identification. All hosts on the same physical network use the same network identifier, and each host on the network (including workstations, servers and routers on the network, etc.). ) has a corresponding host identifier? The four bytes of IP address are divided into two parts, one of which is used to represent the specific network segment, that is, the network identification; The other part is used to identify specific nodes, that is, host identification, that is, a specific computer number in a network. For example, the server IP address of Yancheng Information Network Center is 2 10.73. 140.2. For this IP address, we can divide it into two parts: network identification and host identification, so that the above IP address can be written as:
Network logo: 2 10.73. 140.0
Host ID: 2
Write together: 2 10.73. 140.2.
Because there may be different computers in the network, some networks may contain more computers, and some networks may contain fewer computers, people set 32-bit address information into three positioning methods according to the size of the network, corresponding to Class A, Class B and Class C IP addresses respectively.
1 class. Ip address
Class A IP address refers to the four segments of an IP address, the first segment is the network number, and the other three segments are the numbers of the local computer. If the IP address is expressed in binary, the Class A IP address consists of a network address of 1 byte and a host address of 3 bytes, and the highest bit of the network address must be "0". Among the Class A IP addresses, the length of the network identifier is 7 bits, and the length of the host identifier is 24 bits. The number of Class A network addresses is small, which can be used for large networks with more than160,000 hosts.
2. Class B IP address
Class B IP address refers to the four digits of an IP address, the first two of which are network numbers. Class B IP address consists of two bytes of network address and two bytes of host address. The most significant bit of the network address must be "10". In class B IP address, the length of network identification is 14 bits, and the length of host identification is 16 bits. Class B network addresses are suitable for medium-sized networks, and each network can accommodate more than 60,000 computers.
3. Class C IP address
Class C IP address refers to the four sections of an IP address, the first three sections are the network number, and the remaining section is the number of the local computer. If the IP address is expressed in binary, the Class C IP address consists of a 3-byte network address and a 1 byte host address, and the highest bit of the network address must be "1 10". The length of network identification in class C IP address is 2 1 bit, and the length of host identification is 8 bits. Class C network has many addresses and is suitable for small-scale local area networks. Each network can only accommodate 254 computers at most.
In addition to the above three types of IP addresses, there are several special types of IP addresses. According to the TCP/IP protocol, any address whose first byte begins with "lll0" is called a multicast address. So any IP address with the first byte greater than 223 and less than 240 is a multicast address; An address in which every byte in the IP address is 0 ("0.0.0.0") corresponds to the current host; The IP address ("255.255.255.255") in which every byte in the IP address is 1 is the broadcast address of the current subnet; All IP addresses with "llll0" are reserved for special use in the future; The IP address cannot start with decimal "127", and 27. 1. 1 is used for loop testing. At the same time, the first 6 groups of the network ID cannot all be set to "0", indicating the local network.
Three. IP addressing rules
1. network addressing rules
A. the network address must be unique.
B the network logo cannot start with the number 127. In Class A addresses, 127 is reserved for the internal loopback function.
The first byte of the c network identifier cannot be 255. The number 255 is used as the broadcast address.
D the first byte of the network identifier cannot be "0", which means that the address is a local host and cannot be transmitted.
2. Host addressing rules
Host identification must be unique in the same network.
B all bits of the host identifier cannot be "1". If all bits are "1", the address of the host is the broadcast address, not the address of the host.
C all bits of the host identifier cannot be "0". If all bits are "0", it means "only this network" and there is no host on this network.
Four. Overview of IP subnet mask
The concept of 1. subnet mask
A subnet mask is a 32-bit address used to mask a part of an IP address to distinguish the network identification from the host identification, and to indicate whether the IP address is on a local area network or a remote network.
2. Determine the number of subnet masks
The number of bits used for the subnet mask depends on the number of possible subnets and the number of hosts per subnet. Before defining the subnet mask, it is necessary to find out the number of subnets and hosts used initially.
To define a subnet mask:
A. determine which group addresses we use. For example, the network number we applied for is "2 10.73.a.b", the network address is a class C IP address, the network identifier is "2 10.73" and the host identifier is "a.b".
B, according to the number of subnets we need now and the number of subnets we may expand to in the future, use some bits of the host to define the subnet mask. For example, we need 12 subnets now, and may need 16 subnets in the future. Use the first four bits of the third byte to determine the subnet mask. The first four bits are all set to "1", that is, the third byte is "110000", which is temporarily called the new binary subnet mask.
C all bits corresponding to the initial network are set to "1", that is, the first two bytes are set to "1" and the fourth byte is set to "0". Then the discontinuous binary form of the subnet mask is: "1111111/.
D, convert this number into discontinuous decimal form: "255.255.240.0"
This number is the subnet mask of this network.
Mark of 3.3. IP mask
I. Subnet-free Representation
For an IP address without a subnet, it can be written as a mask with a host number of 0. For example, the IP address is 2 10.73. 140.5, and the mask is 255.255.255.0. You can also default to the mask and write only the IP address.
B, using the method of subnet marking
When there are subnets, they must appear in pairs. Take a class C address as an example.
The first three bytes of 1.IP address indicate the network number, the last byte indicates the subnet number and host number, and it also indicates whether the two IP addresses belong to a network segment. If they belong to the same network interval, the information exchange between these two addresses will not go through the router. If they are not in the same network interval, that is, the subnet numbers are different, the information exchange between the two addresses will be carried out through the router. For example, for a host with IP address 2 10.73. 140.5, its host identifier is 0000 10 1, and for an IP address 210.73.140./ The first three digits of the above two hosts' identification are 000, which means that the two IP addresses are in the same network area, and the two hosts do not need to exchange information through the router. The host identifier of 10.73.60. 1 is 000000 1. The host identifier of 2 10.73.60.252 is111100. The first three digits of the two host identifiers 000 are different from 0 1 1. The subnet host numbers are 1 and 252 respectively.
2. The function of mask is to indicate that there are subnets and how many subnets there are, but the number of subnets can only be expressed as a range, and specific subnets cannot be specified. The mask does not specify a specific subnet number, but has a subnet mask format (for class C addresses):
Verb (abbreviation of verb) Other matters of intellectual property rights.
1. Generally, Internet information centers assign IP addresses according to the network, so only when network addresses are involved can they use the expressions of Class A, Class B and Class C;
2. When assigning network addresses, the network identification is fixed, while the computer identification can be changed within a certain range. The following are three forms of network addresses:
Class A address: 73.0.0.0
Class b address: 160. 153.0.0.
Class C address: 2 10.73. 140.0.
Each of the above zeros can vary from 0 to 255.
3. Because the first three digits of the IP address have already decided what kind of network the IP address belongs to, class A network address can no longer be divided into class B IP addresses, and class B IP addresses can no longer be divided into class C IP addresses.
4. When talking about the specific computer IP address, it is not appropriate to use the expressions of class A, class B and class C, but it can be said which class A, class B and class C network the host address belongs to.
Through the above study, everyone must know something about IP addresses. With an IP address, people can send emails and get other information on the Internet, such as WWW service, BBS service, FTP service and so on.
By mutual consent.
Application of "Remote Assistance" in Windows XP System
Remote assistance is a simple remote control method provided by Windows XP system. The initiator of remote assistance sends a request for assistance to the contact person in Messenger through MSN Messenger, and after obtaining the consent of the other party, remote assistance can be carried out. In remote assistance, the computer of the assisted party will be temporarily controlled by the assisted party (called an expert in the remote assistance program), and the expert can carry out system maintenance, install software, deal with some problems in the computer, or demonstrate some operations to the assisted party.
If you have installed MSN Messenger 6. 1, you also need to install Windows Messenger 4.7 to perform Remote Assistance.
When using remote assistance, you can click the menu command "Operation → Seek Remote Assistance" in the main dialog box of MSN Messenger (as shown in Figure 2). Then select the contact to invite in the "Seek Remote Assistance" dialog box that appears. When the invitation is accepted, the Remote Assistant dialog box will open. The invitee can control the inviter's computer by clicking the Take Control button in the Remote Assistance dialog box.
As in MSN Messenger, master and slave devices can also type messages, talk and send files in the remote assistance dialog box. If the defendant wants to terminate the control, he can press the Esc key or click the "Stop Control" button to get back the control of the computer.
Application of 2.2. Windows XP "Remote Desktop"
Remote control using remote assistance is very simple to realize, but it can only be carried out with the cooperation of master equipment and slave equipment. Therefore, Windows XP Professional Edition provides another remote control method-remote desktop. With the remote desktop, you can remotely control the computer through the network in a place far away from the office. Even if there is no host, the remote desktop can still be carried out smoothly. In this way, remote users can use the data, applications and network resources in the computer, and it can also let your colleagues visit your computer's desktop to facilitate collaborative work.
(1) Configure Remote Desktop Host
The host of remote desktop must be a computer with Windows XP installed. The host must be connected to the Internet and have a legal public IP address. The Internet connection mode of the host computer can be ordinary dial-up mode, because the "remote desktop" can realize remote control only by transmitting a small amount of data (such as display data and keyboard data).
To start the remote desktop function of Windows XP, you must log on to the system as an administrator or a member of the administrators group, so that you have the right to start the remote desktop of Windows XP.
Right-click the My Computer icon and choose the Properties command. Click the Remote tab in the dialog box that appears, and then click the Select Allow users to connect to this computer remotely option box. Click the Select Remote User button, and then click the Add button in the Remote Desktop User dialog box, and the Select User dialog box will appear. (as shown in figure 3)
Click the Location button to specify the search location, and click the Object Type button to specify the object type to search. Next, in the Enter the name of the object to select box, type the name of the object to search for, and then click the Check Name button. After finding the user name, click OK to return to the Remote Desktop User dialog box, and the found user will appear in the user list of the dialog box.
If there are no users available, you can create them by using a user account in the Control Panel. All users listed in the Remote Desktop User List can connect to this computer using Remote Desktop. If they are members of the administrative group, they have the right to connect even if they are not listed here.
(2) Install the client software
Users of Windows XP can connect to the remote desktop through the "Remote Desktop Connection" program that comes with the system (in "Start → All Programs → Accessories → Communication") (as shown in figure 1). If the customer's operating system is Windows 9X/2000, they can install the Remote Desktop Connection client software on the Windows XP installation CD.
Insert the Windows XP installation CD into the client's optical drive. On the welcome page, click the "Perform Other Tasks" option, then select the "Set up Remote Desktop Connection" option on the page that appears, and then follow the prompts to install.
(3) Access the remote desktop
Running the Remote Desktop Connection program on the client will display the Remote Desktop Connection dialog box. Click the Options button to expand all the options in the dialog box, as shown in Figure 2. Type the IP address or domain name, user name and password of the remote host in the General tab, and then click the Connect button. After the connection is successful, the Remote Desktop window will open and you can see the desktop on the remote computer.
If you log out and end Remote Desktop, you can click the Start button in the Remote Desktop Connection window, and then log out as usual.
(4) Web connection of remote desktop
Remote Desktop also provides a Web connection function, which is referred to as "Remote Desktop Web Connection" for short, so that the client can use the "Remote Desktop" function without installing special client software, which has lower requirements for the client and is more flexible to use. Almost any computer that can run IE browser can use the "Remote Desktop" function.
First, let's look at the configuration of the server.
Because Remote Desktop Web Connection is an optional WWW service component in Internet Information Services (IIS), it must be installed before Windows XP host can provide Remote Desktop Web Connection. The method is: run Add or Remove Program Items in the Control Panel, then click Add/Remove Windows Component Options in the Add or Remove Program dialog box, select Internet Information Service Options in the Windows Component Wizard dialog box, click the Details button, select World Wide Web Services → Remote Desktop Web Connection Items, and then return to the options.
Next, run the "Internet Information Service" program in "Administrative Tools", expand the folder hierarchy in turn, find the "tsweb" folder, and right-click the "Properties" command.
Click the Directory Security tab in the Properties dialog box that appears, click the Edit button in the Anonymous Access and Authentication Control column, and select the Anonymous Access option in the Authentication Method dialog box that appears. So we can use IE to access the "Remote Desktop".
Run IE browser on the client and enter the server address in the address bar according to the format of "http:// server address (domain name) /tsweb". If the server address is 2 18.76.2 19.5, you can enter "http://218.76.26439.000000000005" and the "Remote Desktop Web Connection" page will appear in the IE window, as shown in Figure 3. Type the name of the remote computer you want to connect to in the "Server" column of the webpage, and then click the "Connect" button to connect to the remote desktop.
In addition to remote desktop and remote assistance, Windows XP also provides the program sharing function, which is also the remote control of the program in a sense, and NetMeeting also has the program sharing function.
All the above remote control methods can only be carried out in Windows XP or Windows Server 2003, and their functions are relatively simple. In order to carry out remote control in other operating systems or provide more powerful functions through remote control, other third-party remote control software is needed.