🚀 DevOps Basics: Getting Started with Networking

🌍 OSI & TCP/IP Models – How Data Travels Across Networks

Networks function like a well-organized postal system for data, ensuring information is efficiently transmitted, received, and understood. The OSI Model (7 layers) and TCP/IP Model (4 layers) are frameworks that describe this process. Each layer has a specific role in managing data transmission.

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OSI Model (7 Layers)

The OSI (Open Systems Interconnection) model provides a structured approach to how data moves through a network, from the user interface to physical transmission.

1. Application Layer

• Acts as the interface between users and the network.

• Handles services like web browsing, email, and messaging.

• Common protocols: HTTP, HTTPS, FTP, SMTP, POP3, IMAP, DNS.

2. Presentation Layer

• Formats and encrypts data for secure communication.

• Ensures compatibility across different systems.

• Handles compression, encoding, and encryption.

• Example formats: JPEG, MP3, TLS, SSL.

3. Session Layer

• Establishes, manages, and terminates connections between devices.

• Ensures data exchanges happen properly between sender and receiver.

• Protocols: RPC, NetBIOS, PPTP, SOCKS.

4. Transport Layer

• Guarantees reliable communication between devices.

• Provides error checking and ensures complete data delivery.

• Common protocols: TCP (reliable) and UDP (fast, but less reliable).

5. Network Layer

• Determines the best path for data to travel.

• Assigns IP addresses to packets.

• Handles routing decisions.

• Protocols: IP, ICMP, IGMP.

6. Data Link Layer

• Ensures error-free transmission between directly connected nodes.

• Divides data into frames for delivery.

• Protocols: Ethernet, MAC (Media Access Control), ARP (Address Resolution Protocol).

7. Physical Layer

• Transmits raw data as electrical, optical, or radio signals.

• Defines hardware aspects like cables, switches, and wireless networks.

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TCP/IP Model (4 Layers)

The TCP/IP (Transmission Control Protocol/Internet Protocol) model is a more simplified version of OSI, widely used for real-world internet communication.

1. Application Layer

• Functions similarly to the OSI Application, Presentation, and Session layers.

• Handles protocols such as HTTP, SMTP, FTP, DNS.

2. Transport Layer

• Ensures reliable or fast communication using TCP (error-checked) or UDP (speed-focused) protocols.

3. Internet Layer

• Defines how packets move across networks using IP addressing, routing, and forwarding.

4. Network Access Layer

• Combines OSI's Data Link and Physical layers to manage the actual data transmission.

🔗 DevOps Protocols & Ports

Different network services use specific protocols and port numbers to communicate. Some of the most important ones in DevOps include:

• HTTP/HTTPS (80/443) – Loads websites securely.

• FTP (21) – Transfers files between systems.

• SSH (22) – Secure remote login to servers.

• DNS (53) – Converts domain names (like google.com) into IP addresses.

These protocols keep applications running smoothly and securely across networks!

☁️ AWS EC2 & Security Groups – Cloud Basics

AWS EC2 lets you create a virtual server in the cloud. But security matters!

• Security Groups act like firewalls, controlling access to your cloud instance.

• They define rules for what kind of traffic can enter or leave your server.

By setting up security rules, you ensure your cloud environment is safe and efficient

🔍 Essential Networking Commands

DevOps engineers often use commands to check connectivity, troubleshoot networks, and interact with servers. Here are some useful ones:

• ping – Tests if a system is reachable.

• traceroute / tracert – Tracks how data moves across networks.

• netstat – Shows active network connections.

• curl – Sends HTTP requests via the command line.

• dig / nslookup – Looks up domain names and IPs.

These commands help diagnose and optimize network performance!