Introduction

TCP/IP is a suite of communication protocols used to connect devices on the internet. Understanding the workings of TCP/IP is crucial for network administrators and engineers. In this blog post, we will provide a detailed explanation of TCP/IP using Wireshark, a popular network analysis tool.

TCP/IP Layers

The TCP/IP suite is composed of four layers: the application layer, transport layer, internet layer, and network access layer. Each layer is responsible for a specific aspect of network communication.

Application Layer

The application layer is responsible for providing communication services to applications, such as email clients and web browsers. This layer includes protocols such as HTTP, FTP, SMTP, and Telnet.

Transport Layer

The transport layer is responsible for ensuring reliable data transfer between devices. This layer includes two protocols: Transmission Control Protocol (TCP) and User Datagram Protocol (UDP). TCP provides reliable, ordered, and error-checked delivery of data, while UDP provides unreliable and unordered delivery.

Internet Layer

The internet layer is responsible for addressing, routing, and fragmenting data packets. This layer includes the Internet Protocol (IP), which provides connectionless delivery of packets across multiple networks.

Network Access Layer

The network access layer is responsible for delivering data across a specific physical network, such as Ethernet or Wi-Fi. This layer includes protocols such as Ethernet, Wi-Fi, and Point-to-Point Protocol (PPP).

TCP/IP in Wireshark

Wireshark allows you to capture and analyze TCP/IP traffic in real-time. Let’s examine each layer of TCP/IP using Wireshark.

Application Layer

Wireshark provides a list of protocols used at the application layer in the ‘Packet List’ pane. For example, HTTP traffic will be listed as ‘HTTP’ in the ‘Protocol’ column.

Transport Layer

Wireshark displays the TCP or UDP protocol in the ‘Protocol’ column for each packet. You can examine the details of each TCP or UDP packet in the ‘Packet Details’ pane. This includes the source and destination ports, sequence numbers, and acknowledgment numbers.

Internet Layer

Wireshark displays the IP protocol in the ‘Protocol’ column for each packet. You can examine the details of each IP packet in the ‘Packet Details’ pane. This includes the source and destination IP addresses, time-to-live (TTL), and flags.

Network Access Layer

Wireshark displays the specific protocol used at the network access layer in the ‘Protocol’ column for each packet. For example, Ethernet traffic will be listed as ‘Ethernet II’ in the ‘Protocol’ column.

Conclusion

Understanding TCP/IP is essential for anyone working in computer networking. Wireshark provides a powerful tool for examining TCP/IP traffic in real-time. By examining the layers of TCP/IP using Wireshark, you can gain valuable insights into network communication and troubleshoot network issues more effectively. We hope this blog post has provided you with a detailed explanation of TCP/IP using Wireshark. For more informative blog posts on network analysis and optimization, visit Network ThinkTank.