WHAT IS FTP,TCP

#beginners #computerscience #networking #tutorial

1. File Transfer Protocol(FTP)

File transfer protocol(FTP) is an application layer protocol that Used to file transfer between client and a server over a TCP,IP Network.It's provide a standardized method for file exchange across Different system.
- Support text,image,binary,and program files.
- Enable uploading,downloading,and remote file management.
- Used to TCP for ensure reliable communication.

Working and Uses of FTP

FTP follows a client-server model and uses two connections
Control connection (port 21) for commends.
Data connection(port 20)for file transfer.
User connect to the server use login credentials.
User navigate directories used commends ls and cd.
Using for transferring files uses get and put.
supports both active and passive mods for communication.


         control channel 
client -------------------> sever 
       <------------------                     
           Data channel

Types of Connection in FTP

FTP use two separate TCP connection to handle communication one dedicating to control information and another dedicating to actual data transfer
Control connection
data connection

FTP Data Types

FTP data types define how file contents are represented and transmitted between the client and server during file transfer.

ASCII: This data type is used for transferring text files with character encoding based on the ASCII standard.
EBCDIC: This data type is used for transferring text files encoded in IBM’s Extended Binary Coded Decimal Interchange Code.
Image (Binary): This data type transfers files as a continuous stream of bytes without any modification.
Local: This data type is used for transferring files that contain data stored in logical bytes of a specified bit length.

FTP common commends

get filename - download a single file in the server.
mget filename - download a multiple files form the server.
ls - used for list of the files in the current server directory.

Types of FTP

Anonymous FTP
Password-Protected FTP
FTPS (FTP Secure)
SFTP (SSH File Transfer Protocol)
(TBD)

2. Transmission control protocol(TCP)

Transmission control protocol is the protocol that allow the device communicate reliable a network.It is ensure that data reaches the destination correctly and a right order.Even the part of the network slow and unreliable.

It works at the Transport Layer (Layer 4) of the OSI model and is an essential part of the TCP/IP protocol suite used for Internet communication.
TCP establishes a logical connection between the sender and receiver before data transmission begins.
It ensures that data is delivered accurately and in the same order in which it was sent using acknowledgements and sequence numbers.
TCP detects errors using checksums and retransmits lost or corrupted packets to maintain data integrity.
It controls the data transmission rate to avoid overwhelming the receiver and adapts to network congestion for efficient communication.

Connection Establishment (Three-Way Handshake)

TCP is connection-orientated, meaning a connection must be established before any data is sent. This is done using a three-way handshake

TCP Handshake process

           FIN-ACK
       -------------->
             ACK
       <------------- 
           ACK-FIN
 Client<--------------Server  
             ACK
      --------------->

Step 1: FIN (Client → Server): The client sends a FIN segment to initiate closure, entering the FIN-WAIT-1 state.

Step 2: ACK (Server → Client): The server sends an ACK to acknowledge the FIN. The server enters CLOSE-WAIT (can still send data), and the client enters FIN-WAIT-2.

Step 3: FIN (Server → Client): Once the server finishes sending remaining data, it sends its own FIN segment to the client.

Step 4: ACK (Client → Server): The client sends an ACK to acknowledge the server's FIN, entering the TIME-WAIT state. After a set period, the connection is fully closed.

WORKING