FTP represents File transfer protocol and it is a standard internet protocol supported by TCP/IP used for transmitting the files from one host to another. FTP needs TCP as a transport protocol to help the reliable end to end connections and executes two types of connections in managing data transfers.
The FTP clients initiate the first connection, referred to as the control connection, to wellknown port 21 (the clients port is typically ephemeral). It is on this part that an FTP server listens for it and accepts new connections. The control connection is issued for all of the control commands a client user uses to log on to the server, manipulate files, and terminate a session. This is also the relationship across which the FTP server will transmit messages to the client in response to their control commands.
The second connection used by FTP is defined as the data connection. Typically, the data connection is established on the server port 20. It depends on how the data connection is established; both the client and server can use ephemeral ports. It is across the connection that FTP shares the information.
FTP opens a data connection when a user concerns a command requiring a data transfer, including a request to retrieve a file or to view a list of the files available. Therefore, an entire FTP session can open and close without a data connection ever having been opened.
In other words, when a client starts an FTP session, the control connections open while the control connection is open, and the data connection can be opened and closed multiple times if several files are transferred.
The advantages of FTP are as follows −
The standard requirement of the market is that all FTP transmissions should be encrypted. However, not all FTP providers are equal and not all provider's support encryption. FTP serves two operations, such as sending and receiving huge files on a network. The size limit of the file is 2GB that can transmit.
Passwords and file text are sent in clear text that enables unwanted eavesdropping. Therefore, it is quite possible that attackers can carry out the brute force attack by trying to guess the FTP password.
It is not compatible with every system.