(Ftp) file transfer protocol

The File Transfer Protocol (FTP) is a standard network protocol used for the transfer of computer files between a client and server on a computer network. FTP is built on a client-server model architecture using separate control and data connections between the client and the server.

1. FTP
File Transfer Protocol
Gouasmia Zakaria
[email protected]

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
RecordR 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 !