Application Layer Protocols In OSI Reference Model

There are three basic protocols we are discussed in the application layer. These are used to transfer files over the computer network.

1.FTP

2.SFTP

3.TFTP

1.FTP - File Transfer Protocol (Port Number = 21) :

*It has two channels, one is for data and the second is for command. (Out - of- band protocol)

*It has no encryption, so data tempering is possible.

*It uses TCP for data communication. It is reliable communication.

For example, first we have to send command and after server send port command to give the location of the port for data transfer. Then Data connection is established for access and download files.

2.SFTP - SSH(Secure shell)File Transfer Protocol(Port Number = 22) :

*It has a single channel for data and command.(In-band Protocol)

*Both data and command are encrypted in SFTP.

*It uses TCP for data communication. So, it is reliable communication.

3.TFTP - Trivial File Transfer Protocol (Port Number = 69) :

*It doesn't require authentication, making it less secure than FTP and SFTP

*It uses UDP for data communication. It is unreliable communication

*It is not used over the internet, it is mainly used for transferring files within LAN.