Day 23 Tasks : 23/90 Days of DevOps

• Before moving further , lets revise what we had done till now
• Tasks :
• 1) Revise all the linux commands which you have learned till now
• 2) Revising Networking concepts:
• a) OSI model TCP model
• b) IP addressing and subnetting
• c) why networking concept are necessary for devops

Write a Article on Linkedin about above topics and share it with connections.

Answers=>

1) => Linux commands and their short descriptions:

1. ls: List directory contents.
2. cd: Change the current directory.
3. pwd: Print working directory.
4. mkdir: Make directories.
5. rmdir: Remove empty directories.
6. rm: Remove files or directories.
7. cp: Copy files or directories.
8. mv: Move or rename files or directories.
9. cat: Concatenate and display files.
10. more: Display output one screen at a time.
11. less: Display output one screen at a time, with backward navigation.
12. head: Display the beginning of a file.
13. tail: Display the end of a file.
14. grep: Search for patterns in files.
15. wc: Count words, lines, or characters in a file.
16. chmod: Change file permissions.
17. chown: Change file owner and group.
18. sudo: Execute a command as the superuser.
19. su: Switch user or become another user.
20. passwd: Change user password.
21. ssh: Secure Shell, remote login.
22. scp: Secure Copy, transfer files securely between hosts.
23. tar: Tape archive, used for archiving and compression.
24. gzip: Compress or expand files.
25. gunzip: Decompress compressed files.
26. zip: Package and compress files.
27. unzip: Unpack zip archives.
28. df: Display free disk space.
29. du: Display disk usage.
30. top: Display system processes.
31. ps: Display process status.
32. kill: Terminate processes.
33. bg: Put a process in the background.
34. fg: Bring a process to the foreground.
35. shutdown: Shutdown or restart the system.
36. reboot: Reboot the system.
37. ifconfig: Configure network interfaces.
38. ping: Test network connectivity.
39. netstat: Display network connections, routing tables, interface statistics.
40. hostname: Display or set the system's hostname.
41. date: Display or set the system date and time.
42. cal: Display a calendar.
43. find: Search for files in a directory hierarchy.
44. locate: Find files by name.
45. wget: Download files from the internet.
46. curl: Transfer data from or to a server.
47. vim (or vi): Text editor.
48. nano: Simple text editor.
49. echo: Display a line of text.
50. clear: Clear the terminal screen.
51. exit: Exit the current shell or terminal session.

2)=> OSI Model:

The OSI model is a theoretical framework developed by the International Organization for Standardization (ISO) to standardize network communication. It consists of seven layers, each representing a different aspect of network communication.

1. Physical Layer: This layer deals with the physical transmission of data over the network medium, including characteristics such as cables, connectors, and electrical signals.
2. Data Link Layer: The data link layer is responsible for framing data into frames and transmitting them reliably across the physical layer. It also handles error detection and correction.
3. Network Layer: This layer deals with the routing and forwarding of data packets between different networks. It provides logical addressing (IP addresses) and determines the best path for data to travel.
4. Transport Layer: The transport layer ensures end-to-end communication between hosts. It is responsible for segmentation and reassembly of data, flow control, error detection, and reliable delivery. Examples of protocols at this layer include TCP (Transmission Control Protocol) and UDP (User Datagram Protocol).
5. Session Layer: The session layer establishes, maintains, and terminates connections between applications on different devices. It manages sessions and ensures that data is transferred securely and reliably.
6. Presentation Layer: This layer is responsible for data representation and translation, including encryption, compression, and data formatting.
7. Application Layer: The application layer provides network services directly to end-users or applications. It includes protocols such as HTTP, FTP, SMTP, and DNS.

TCP/IP Model:

The TCP/IP model is a simplified version of the OSI model and is widely used in modern networking, especially in the context of the Internet. It consists of four layers:

1. Network Interface Layer: Equivalent to the combination of the OSI physical and data link layers, this layer deals with the physical transmission of data and the framing of packets.
2. Internet Layer: Comparable to the OSI network layer, this layer handles the routing of packets across different networks. It is responsible for logical addressing (IP addresses) and packet forwarding.
3. Transport Layer: Similar to the OSI transport layer, this layer provides end-to-end communication between hosts. It includes protocols such as TCP for reliable, connection-oriented communication, and UDP for unreliable, connectionless communication.
4. Application Layer: This layer corresponds to the combination of the OSI session, presentation, and application layers. It provides network services directly to applications and end-users, including protocols like HTTP, FTP, SMTP, and DNS.

3)=>

1. IP Addressing: An IP (Internet Protocol) address is a unique numerical label assigned to each device connected to a computer network that uses the Internet Protocol for communication. IP addresses are essential for devices to communicate with each other over a network, just like how houses have unique addresses for mail delivery.There are two main versions of IP addresses currently in use: IPv4 and IPv6. IPv4 addresses are 32-bit numerical addresses written in the form of four decimal numbers separated by periods (e.g., 192.168.1.1). IPv6 addresses are 128-bit hexadecimal addresses, which allow for a much larger number of possible unique addresses compared to IPv4.IPv4:IPv4 addresses are 32-bit numerical addresses, typically expressed as four decimal numbers separated by periods (e.g., 192.168.1.1).The 32 bits are divided into four octets, each containing 8 bits.IPv4 addresses provide approximately 4.3 billion unique addresses, which were thought to be more than enough when IPv4 was designed several decades ago. However, with the rapid growth of the Internet and the proliferation of connected devices, the available IPv4 addresses are now running out.IPv4 addresses are still widely used today and are the most commonly deployed version of IP on the Internet.IPv6:IPv6 addresses are 128-bit numerical addresses, typically expressed as a series of hexadecimal numbers separated by colons (e.g., 2001:0db8:85a3:0000:0000:8a2e:0370:7334).The 128 bits are divided into eight groups of 16 bits each.IPv6 was developed to address the limitations of IPv4, particularly the exhaustion of available addresses. IPv6 provides an enormous address space, capable of accommodating approximately 340 undecillion unique addresses (that's 3.4 × 10^38 addresses).Besides the larger address space, IPv6 also offers other advantages over IPv4, including improved routing efficiency, simpler header format, built-in security features, and support for auto-configuration.Classes in IPv4:Class A:Class A addresses were identified by the first bit being set to 0, which meant the range of Class A addresses was from 0.0.0.0 to 127.255.255.255.The first octet (8 bits) was used to represent the network portion, and the remaining three octets (24 bits) were used for host addresses.Class A addresses were designed for large organizations or ISPs because they could accommodate a very large number of hosts (up to approximately 16 million).Class B:Class B addresses were identified by the first two bits being set to 10, which meant the range of Class B addresses was from 128.0.0.0 to 191.255.255.255.The first two octets (16 bits) were used to represent the network portion, and the remaining two octets (16 bits) were used for host addresses.Class B addresses were suitable for medium-sized organizations because they could accommodate a moderate number of hosts (up to approximately 65,000).Class C:Class C addresses were identified by the first three bits being set to 110, which meant the range of Class C addresses was from 192.0.0.0 to 223.255.255.255.The first three octets (24 bits) were used to represent the network portion, and the remaining octet (8 bits) was used for host addresses.Class C addresses were used for small networks or subnets within larger networks because they could accommodate a smaller number of hosts (up to approximately 254).

Classes D and E were reserved for special purposes:

• Class D addresses (first four bits set to 1110) are used for multicast addressing, where packets are sent to multiple recipients simultaneously.
• Class E addresses (first four bits set to 1111) were reserved for experimental and research purposes and were never used for general addressing. 2) Subnetting: Subnetting is the process of dividing a larger network into smaller sub-networks, or subnets. This practice is commonly used for various reasons, including improving network performance, security, and efficient use of IP addresses.When you subnet a network, you create multiple smaller networks within the larger network, each with its own range of IP addresses. This allows for better organization and management of network resources.Subnetting involves borrowing bits from the host portion of an IP address to create a network portion and a host portion. The number of bits borrowed determines the size of the subnet and the number of possible subnets and hosts within each subnet.For example, if you have the IP address 192.168.1.0 with a subnet mask of 255.255.255.0 (which is often represented as "/24" in CIDR notation), it means that the first 24 bits represent the network portion, and the last 8 bits represent the host portion. In this case, you have created a subnet with 256 possible addresses (from 192.168.1.0 to 192.168.1.255), where the first three octets (192.168.1) are used to identify the network, and the last octet (0 to 255) identifies specific hosts within that network.Subnetting allows for efficient allocation of IP addresses and helps to reduce network congestion by limiting the broadcast domain size within each subnet. It also enhances security by isolating different parts of the network from each other.

4)=>Why Learning and sticking to basic networking concepts are necessary for DevOps engineer

1. Understanding Infrastructure: DevOps involves the collaboration between development and operations teams to automate and streamline the software delivery process. This often includes deploying applications to various infrastructure environments, such as on-premises servers, cloud platforms, or containerized environments. A solid understanding of networking concepts allows DevOps engineers to design, deploy, and manage these infrastructure environments effectively.
2. Troubleshooting and Debugging: In a distributed system, understanding networking is essential for troubleshooting issues related to application performance, connectivity, or security. DevOps engineers need to be able to identify and resolve network-related problems quickly to ensure the reliability and availability of the software services they manage.
3. Security: Networking concepts play a critical role in ensuring the security of applications and infrastructure. DevOps engineers need to understand concepts like firewalls, VPNs, encryption, and network segmentation to implement robust security measures and protect sensitive data from unauthorized access or attacks.
4. Optimization and Performance Tuning: Knowledge of networking helps DevOps engineers optimize the performance of applications and infrastructure. This includes tasks such as load balancing, traffic routing, bandwidth management, and minimizing latency. By understanding how data flows across networks, DevOps teams can implement optimizations that improve application responsiveness and scalability.
5. Integration with Cloud Services: Cloud computing has become integral to modern software development and deployment. Understanding networking concepts is essential for leveraging cloud services effectively, whether it's setting up virtual networks, configuring subnets, managing security groups, or establishing connectivity between on-premises and cloud environments.
6. Automation and Orchestration: DevOps emphasizes automation to streamline processes and eliminate manual tasks. Networking concepts enable DevOps engineers to automate the provisioning, configuration, and management of network resources using tools like Ansible, Terraform, or Kubernetes. This automation ensures consistency, repeatability, and scalability in managing network infrastructure.
7. Cross-functional Collaboration: DevOps promotes collaboration between development, operations, and other stakeholders involved in the software delivery lifecycle. Having a common understanding of networking concepts facilitates communication and collaboration between teams, enabling them to work together more effectively to achieve common goals.