FTP server (file transfer protocol server) is a kind of cloud server. Computers that provide document storage and access services on the Internet. They provide services according to the FTP protocol. FTP is the file transfer protocol. As the name suggests, it is a protocol specially used to transmit documents. Simply put, a server that supports the FTP protocol is an FTP server. It is used to transfer documents between two computers. It is one of the most widely used services in the Internet. It can set the permissions of each user according to the actual needs. At the same time, it also has cross platform characteristics, that is, FTP client and server can be realized in UNIX, Linux, windows and other operating systems, and documents can be transmitted across platforms. Therefore, FTP service is one of the resource sharing methods often used in the network. FTP protocol has two working modes: port and PASV, namely active mode and passive mode.