The document provides an overview of the File Transfer Protocol (FTP), detailing its network architecture, control and data connections, and authentication methods. It also describes the two connection modes (active and passive), file structures, and transmission modes used in FTP. The main function of FTP is to facilitate the exchange of files over TCP/IP networks.

1. FTP
File Transfer Protocol
Gouasmia Zakaria
Gouasmia.zakaria1@gmail.com

2. INTRODUCTION
 What is FTP?
Network Protocol
Exchange files over any network that supports the TCP/IP
protocol
Client-Server Architecture
Separate Data and Control connections
User based password authentication or anonymous user
access

3. PROTOCOL OVERVIEW

4. PROTOCOL OVERVIEW
 Client to Server on TCP Port 21 – Control Connection
Commands
Identifications
Passwords
Interrupt Messages
 Client to Server or vice-versa on TCP Port 20 – Data Connection
Actual File Transfer
 Out-of-Bound Protocol

5. CONTROL CONNECTION
Bi-directional
Initiated by Client

6. DATA CONNECTION
Uni-directional
Can be initiated by both client and server

7. PROTOCOL OVERVIEW
 FTP uses TCP as a Transport Protocol
 The FTP Server, running FTP Server software, listens on the network
 The Client computer, running FTP Client software, initiates connection
 FTP only opens a data connection when a client issues a command
requiring a data transfer
 Possible for an entire FTP session to open and close without a data
connection ever having been opened.

8. CONNECTION MODES
 Active Mode
Client sends Server the IP Address & Port Number
 Passive Mode
Client is behind firewall
Server sends client an IP Address and Port Number

9. Active mode
step 1: the client's command port contacts the server's command port
and sends its data port number i.e.1027.
step 2:The server then sends an ACK back to the client's command port
step 3:The server initiates a connection on its local data port to the
data port the client specified earlier.
step 4: The client sends an ACK back .

10. Passive mode
step 1:The client contacts the server on the command port and issues
the PASV command.
step 2: The server then replies with PORT 2024, telling the client which
port it is listening to for the data connection.
step 3: The client then initiates the data connection from its data port to the
specified server data port.
step 4: The server sends back an ACK to the client's data port.

11. FILE STRUCTURE
 OS stores files in different structures
 FTP defines file structures for different files
 File F Unstructured, sequence of bytes
 Record R Series of records
 Page P Series of data blocks (pages)
 Default File Structure is F
 Specified using STRU command

12. TRANSMISSION MODES
 Stream Mode
Data sent as a continuous stream
All processing left to TCP
End-of-File Indicator not required
 Blocked Mode
FTP breaks data into several blocks
 Compressed Mode
Data compressed using a single algorithm

13. Thank YOU !