TCP/ IP Network Model

TCP/IP Network model
I was intrested in security so i started using tools without knowing the basic knowledge of it , i started with Nmap a port scanning tool on kali linux scanning random ip addresses i did not understand what TCP UDP port was,later started learning about networks.

TCP/IP network model or Transmission Control Protocol/Internet Protocol Network model.
TCP/IP network model has five layers they are:

  1. Application Layer
  2. Transport Layer
  3. Network Layer
  4. Data-link Layer
  5. Physical Layer TCP/IP model

Each layer a different protocols
1.Application layer has HTTP,HTTPS,SMTP,FTP,TELNET.

2.Transport layer has TCP/UDP

TCP stands for Transmission Control Protocol and User Datagram Protocol an example for UDP is video call where continous delivery of packets, if a packet is lost it does not care ,while in TCP if a packet is lost it asks the sender to send it again.

When the data arrives at the transport layer, the protocols at the layer start the process of data encapsulation. The transport layer encapsulates the application data into transport protocol data units.

The transport layer protocol creates a virtual flow of data between the sending and receiving application, differentiated by the transport port number. The port number identifies a port, a dedicated location in memory for receiving or sending data. In addition, the transport protocol layer might provide other services, such as reliable, in order data delivery. The end result depends on whether TCP, SCTP, or UDP handles the information

Establishing a TCP Connection

TCP uses segments to determine whether the receiving system is ready to receive the data. When the sending TCP wants to establish connections, TCP sends a segment that is called a SYN to the TCP protocol on the receiving host. The receiving TCP returns a segment that is called an ACK to acknowledge the successful receipt of the segment. The sending TCP sends another ACK segment, then proceeds to send the data. This exchange of control information is referred to as a three-way handshake.

3.Network layer - IP (logical addressing )ICMP

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