Basic Understanding about FTP

FTP is an abbreviation of File Transfer Protocol, it is the main network protocol used for downloading/uploading of files. From one host to another using a TCP based network like INTERNET. FTP works on a principle of client-server model and uses data-connection between client and server. FTP basically runs on port no 21 as default.

How does FTP work?

A Client makes a TCP connection to the server port 21. This connection remains open for the duration of the session and thus it is called a control session. Then another connection is opened on Port 20 and it is called the data connection. The control connection is used for authenticating, command and administrating exchanged between the client and the server.

Types of FTP

There are two types of FTP.

Passive FTP: - In passive mode, the client establishes both channels (Data and control). In that case, the server tells the client which port should be used for the data channel.

Active FTP: - In active mode, the client establishes the control channel but the server establishes the data channel.