The ftp server is a brief introduction to

Introduction to what is the FTP protocol (File Transfer Protocol). Recommended reading: FTP use command detailed

FTP is the abbreviation of English File Transfer Protocal, translated into Chinese is "file transfer protocol" meaning.

FTP is one of the protocols in the tcp/ip protocol suite and is a protocol for bidirectional transmission of control files on the Internet. At the same time, it is also an application. Users can connect their PCs to all servers running FTP protocols around the world to access a large number of programs and information on the server. Recommended reading: FTP use command detailed

FTP protocol is the basis of internet file transfer, it consists of a series of specification documents, the goal is to improve the sharing of files, provide non-direct use of remote computers, make storage media pairs Users transmit data transparently and reliably and efficiently. Simply put, ftp is to complete a copy between two computers, copy files from a remote computer to their own computer, called "download" & rdquo; file. If you copy a file from your own computer to a remote computer, it is called "upload" file. In the tcp/ip protocol, the ftp standard command tcp port number is 21, and the port mode data port is 20. The task of the ftp protocol is to transfer files from one computer to another, regardless of where they are located, how they are connected, or even whether they use the same operating system. Assuming that two computers talk through the ftp protocol and can access the internet, you can use the ftp command to transfer files. There are some nuances in each operating system, but the basic command structure for each protocol is the same. In general, the primary purpose of user networking is to achieve information sharing. File transfer is one of the most important aspects of information sharing. The early implementation of transferring files on the Internet is not an easy task. We know that the Internet is a very complicated computer environment. There are PCs, workstations, MACs, and mainframes. According to statistics, computers connected to the Internet are already on the Internet. Ten million, and these computers may run different operating systems, there are servers running Unix, PCs running Dos, Windows, Macs running MacOS, etc., and file exchange problems between various operating systems are required. Create a unified file transfer protocol, which is called FTP. There are different FTP applications based on different operating systems, and all of these applications adhere to the same protocol, so users can transfer their files to others or obtain files from other user environments. Like most Internet services, FTP is also a client/server system. The user connects to the FTP server program on the remote host through a client program that supports the FTP protocol. The user issues a command to the server program through the client program, the server program executes the command issued by the user, and returns the result of the execution to the client. For example, the user issues a command asking the server to send a copy of a file to the user, and the server will respond to the command and send the specified file to the user's machine. The client program receives this file on behalf of the user and stores it in the user directory. In the use of FTP, users often encounter two concepts: "Download" (Download) and "Upload" (Upload). "Download" files are files copied from a remote host to their own computers; "Upload" files are copies of files from their own computers to remote hosts. In the Internet language, users can upload (download) files to (from) remote hosts through a client program. When using FTP, you must first log in and obtain the appropriate permissions on the remote host before uploading or downloading files. That is, in order to transfer a file with which computer, you must have the appropriate authorization for which computer. In other words, the file cannot be transferred unless there is a user ID and password. This situation violates the openness of the Internet. There are more than 10 million FTP hosts on the Internet. It is impossible to require each user to have an account on each host. Anonymous FTP is created to solve this problem. Anonymous FTP is a mechanism by which users can connect to and download files from a remote host without becoming a registered user. The system administrator has created a special user ID called anonymous, which can be used by anyone on the Internet anywhere. The way to connect to an anonymous FTP host through an FTP program is similar to the way to connect to an ordinary FTP host. You must enter anonymous when you request a user ID. The password for the user ID can be any string. It is customary to use your own E-mail address as a password to enable the system maintenance program to record who is accessing these files. It's worth noting that anonymous FTP is not available for all Internet hosts, it only works for hosts that offer this service. When a remote host provides an anonymous FTP service, certain directories are specified to be open to the public, allowing anonymous access. The rest of the directories in the system are in a hidden state. As a security measure, most anonymous FTP hosts allow users to download files from them without allowing users to upload files to them. That is, users can copy all files on the anonymous FTP host to their own machines. However, you cannot copy any file on your own machine to an anonymous FTP host. Even if some anonymous FTP hosts do allow users to upload files, users can only upload files to a specific upload directory. Subsequently, the system administrator will check these files, he will move these files to another public download directory for other users to download, in this way, the remote host users are protected, avoiding the problem of someone uploading Files, such as files with viruses. As an Internet user, you can copy files between any two Internet hosts via FTP. However, in fact, most people only have one Internet account. FTP is mainly used to download public files, such as shareware and company technical support files. There are thousands of anonymous FTP hosts on the Internet, and these hosts contain unclear files for free copying. In fact, almost all types of information, all types of computer programs can be found on the Internet. This is one of the important reasons why the Internet attracts us. Anonymous FTP gives users the opportunity to access the world's largest repository of information, which is accumulating over time and growing, never shutting down, involving almost any topic. Moreover, all this is free. Anonymous FTP is a common method of publishing software on the Internet. The reason why the Internet can continue today is because people use programs that provide standard services through standard protocols. Many programs like this are distributed via anonymous FTP and can be accessed by anyone. There are a huge number of anonymous FTP hosts and more files on the Internet, so how do you know which directory on a anonymous FTP host a particular file is on? This is exactly what the Archie server is doing. Archie will automatically search the FTP host to construct a database containing all the file directory information, so that you can directly find the location information of the required files.