FTP

FTP stands for File Transfer Protocol. It is a network protocol used for downloading/uploading of files from one host to another using a TCP/IP based network.

• FTP works on the principle of client-server model. Basically runs on port no. 21 as default.
• A person runs an FTP client application on one computer. Another computer runs an FTP server program.
• We can transfer files, create directories, remove directories, list files between the computers.

FTP consists of two connections

• Control Connection is established between port 21 of server and random port of client. 
• Data Connection is established every time client sends a request using the control connection to server for data transfer. For every new data connection port number changes.

FTP Server may support Active or Passive connections or both.

• In Active mode, client establishes the command channel(from client port 'x' to server port 21) but server establishes the data channel(from server port 20 to client port 'y'), where 'y' is supplied by the client.

• In Passive mode, the client establishes both channels, the server tells the client which port should be used for the data channel.

Five best FTP clients :

• FILEZILLA
• FIREFTP
• CYBERDUCK
• TRANSMIT
• WINSCP