1、 What is the IP address?
Another very important content of IP protocol is that each computer and other devices on the Internet are assigned a unique address, called "IP address". Because of this unique address, it ensures that users can efficiently and conveniently select the objects they need from thousands of computers when operating on networked computers. Nowadays, telecommunication networks are converging with IP networks. New technologies based on IP are popular technologies, such as the technology of voice transmission over IP networks (VoIP). Others, such as IP over ATM, IP over SDH, IP over WDM, are the focus of IP technology research.
2、 What is the port?
TCP: Transmission Control Protocol TCP is a connection oriented (connection oriented), reliable, byte stream based transport layer communication protocol, which is described by RFC 793 of the IETF. In the simplified computer network OSI model, it performs the functions specified by the fourth layer transport layer. UDP is another important transport protocol in the same layer.
UDP: UDP is a connectionless transport layer protocol in the ISO reference model, which provides simple and unreliable transaction oriented information transfer services. UDP protocol is basically the interface between IP protocol and upper layer protocol. UDP protocol is applicable to port discrimination of multiple applications running on the same device.
3、 What does the port do?
As we know, a host with an IP address can provide many services, such as Web services, FTP services, SMTP services, and so on. These services can be realized through one IP address. So, how does the host distinguish between different network services? Obviously, you cannot rely only on IP addresses, because the relationship between IP addresses and network services is one to many. In fact, different services are distinguished by "IP address+port number".
The simple understanding is that, for example, a bank has a door, and there are several windows for service, such as window 1 for bank card business, window 2 for deposit withdrawal business below 100000 yuan, and window 3 for deposit withdrawal business above 1 million yuan. A port is like a bank window. You need to open a window to process business.
Of course, the port is the same. You need to open a window to connect with us and provide some services.
4、 How to find the service/process corresponding to the query?
Command:
Ipconfig --- View local IP information
Netstat – an --- View TCP/UDP ports
netstat –ano
Tasklist --- View process information
tasklist /svc
5、 What are the common ports?
20=ftp data
21=file transfer
22=SSH port
23=Remote terminal
80=hypertext transfer
3306 = MYSQL
3389=Remote Desktop