Roadmap - Backend

Internet

Overview

• The internet is a network of networks.
• The core of the internet is a global network of interconnected routers, which are responsible for directing traffic between different devices and systems.
• To ensure that packets are sent and received correctly, the internet uses a variety of protocols, including the Internet Protocol (IP) and the Transmission Control Protocol (TCP). IP is responsible for routing packets to their correct destination, while TCP ensures that packets are transmitted reliably and in the correct order.

Basic Concepts and Terminology

• Packet: A small unit of data that is transmitted over the internet.
• Router: A device that directs packets of data between different networks.
• IP Address: A unique identifier assigned to each device on a network, used to route data to the correct destination.
• Domain Name: A human-readable name that is used to identify a website, such as google.com.
• DNS: The Domain Name System is responsible for translating domain names into IP addresses.
• HTTP: The Hypertext Transfer Protocol is used to transfer data between a client (such as a web browser) and a server (such as a website).
• HTTPS: An encrypted version of HTTP that is used to provide secure communication between a client and server.
• SSL/TLS: The Secure Sockets Layer and Transport Layer Security protocols are used to provide secure communication over the internet.

The Role of Protocols in Internet

• IP is responsible for routing packets of data to their correct destination, while TCP and UDP ensure that packets are transmitted reliably and efficiently. DNS is used to translate domain names into IP addresses, and HTTP is used to transfer data between clients and servers.

Understanding IP Addresses and Domain Names

When you enter a domain name into your web browser, your computer sends a DNS query to a DNS server, which returns the corresponding IP address. Your computer then uses that IP address to connect to the website or other resource you’ve requested.

HTTP and HTTPS

• HTTP is the protocol used to transfer data between a client (such as a web browser) and a server (such as a website). When you visit a website, your web browser sends an HTTP request to the server, asking for the webpage or other resource you’ve requested. The server then sends an HTTP response back to the client, containing the requested data.
• HTTPS is a more secure version of HTTP, which encrypts the data being transmitted between the client and server using SSL/TLS (Secure Sockets Layer/Transport Layer Security) encryption. This provides an additional layer of security, helping to protect sensitive information such as login credentials, payment information, and other personal data.

Building Applications with TCP/IP

TCP/IP (Transmission Control Protocol/Internet Protocol) is the underlying communication protocol used by most internet-based applications and services. It provides a reliable, ordered, and error-checked delivery of data between applications running on different devices.

• Ports: Ports are used to identify the application or service running on a device. Each application or service is assigned a unique port number, allowing data to be sent to the correct destination.
• Sockets: A socket is a combination of an IP address and a port number, representing a specific endpoint for communication. Sockets are used to establish connections between devices and transfer data between applications.
• Connections: A connection is established between two sockets when two devices want to communicate with each other. During the connection establishment process, the devices negotiate various parameters such as the maximum segment size and window size, which determine how data will be transmitted over the connection.
• Data transfer: Once a connection is established, data can be transferred between the applications running on each device. Data is typically transmitted in segments, with each segment containing a sequence number and other metadata to ensure reliable delivery.

Securing Internet Communication with SSL/TLS

When using SSL/TLS to secure internet communication, there are a few key concepts to understand:

• Certificates: SSL/TLS certificates are used to establish trust between the client and server. They contain information about the identity of the server and are signed by a trusted third party (a Certificate Authority) to verify their authenticity.
• Handshake: During the SSL/TLS handshake process, the client and server exchange information to negotiate the encryption algorithm and other parameters for the secure connection.
• Encryption: Once the secure connection is established, data is encrypted using the agreed-upon algorithm and can be transmitted securely between the client and server.