Computer Networking Concepts for Devops

Why does devops engineer need computer networking concepts?

• To ensure effective network configurations in cloud and on-premise environments.
• Troubleshoot network outages and latency issues effectively.
• Secure network traffic and configure access control.
• Automate network management as part of IaC.
• Support the scaling and performance of distributed systems.

Here are few concepts to give a brief understanding of computer networks:

1. Network Types
2. Network Devices
3. OSI Model
4. TCP/IP Model
5. Network Protocols
6. Ports
7. Subnetting, CIDR
8. Routing
9. DNS
10. VPN 11.Networking tools

A Computer Network is a collection of devices where two or more devices can communicate with each other by sharing data.

Network Types

Networks classified based on the number of devices connected and geographical extent are PAN, LAN, MAN, WAN, WLAN, VPN.

• Private Area Network(PAN): A type of network designed to connect devices within a short range. Best suitable for you personal devices like smart phones, laptops, wearables can be connected.
• Local Area Network(LAN): A type of network that connects computers through a common communication path within a limited area. Best suitable for home, school, college, office setup.
• Metropolitan area network(MAN): A type of network the connects systems over a geographical distance through a shared communication path. Best suitable for towns, cities etc.
• Wide Area Network(WAN): A type of network the connects devices over a large geographical distances through a shared communication path. Example-Internet.
• Wireless Local Area Network(WLAN): A type of local area network which connects devices using wireless communication technologies. Example- wifi.
• Virtual Private Network(VPN): A type of network that allows you to create a secure and private network over internet or public network. This provides security, anonymity, access restriction etc.

Network Devices

Network devices allows hardware on a computer network to communicate with each other.

• Modems: A network device that is used to convert digital signal into analog signals and demodulates them at the recieving location.
• Firewalls: A security device that is designed to protect a computer network from unauthorized access or attacks.
• Repeater: A network device that amplifies the signal and retransmits it to extent the range of the signal.
• Hub: It is a multiport repeater which connects multiple wires coming from different branches.
• Bridge: A bridge is a repeater with add on the fuctionality of filtering content by reading the MAC address of the source and destination.
• Switch: It is a multiport bridge with a buffer that can boost its efficiency and performance.
• Router: It is a switch like device that routes the data based on the IP addresses.
• Gateway: It is a passage to connect different networks often with different protocols.

OSI Model

OSI(Open Sytem Interaction) explains how different computer systems communicate over a network.

1. Application Layer: It's functions are
   • Provides an interface to send and recieve data from user.
   • Provides different protocols like HTTP, FTP, SMTP etc
   • It helps in establishment, maintenance and termination of communication sessions between applications.
2. Presentation Layer: It's functions are
   • Data translation
   • Data encryption for security
   • Data compression for faster communication
3. Session Layer: It's functions are
   • Create and manage sessions between systems
   • Adds checkpoints to ensure proper data transmission
   • Ensures authentication and authorization of data transfer
4. Transport Layer: It's functions are
   • Converts data into segments. A header is associated with each segment where header helps in service point addressing.
   • Flow Control
   • Error Control
5. Network Layer: It's functions are
   • Transmits data from one host to another in the form of packets.
   • Routing the data packets through best possible routes
   • Logical addressing the hosts through unique addressing i.e IP Addressing
6. Data Link Layer: It's functions are
   • converts data packets into frames
   • Error detection using parity check, Checksum, CRC
   • Error correction
   • Flow Control
7. Physical Layer: It's functions are
   • Bit-by-bit transmission
   • Encoding and decoding of a signal
   • Data rate control
   • Decides data rate, mode of communication(simplex, half duplex, full duplex)

Physical Layer, Datalink Layer, Network Layer, Transport layer together are called hardware layers.
Application layer, presentation layer, Session layer together are called software layers.

TCP/IP model

It is more simple and practical model with 4 layers which is why it is extensively used in real world networks.
Layers of TCP/IP models

1. Application Layer: This layer deals with data representation, encoding and dialog control issues.
2. Transport layer: This layer ensures reliable data, error correction, flow control and segmentation of data.
3. Internet Layer: This layer is responsible for routing data packets across different networks and ensuring they reach their destination.
4. Network Access layer: This layer defines how data is formatted, addressed, and transmitted over various types of network.

Network Protocols

TCP Protocol:

• It is responsible for breaking down a stream of bytes into segments and reconnecting them at the other end, retransmitting whatever might be lost and also organizing the segments in the correct order.
• It is connection-oriented.
• It helps in flow and error control

UDP Protocol:

• Unlike TCP it is used when you can establish an unreliable and connection less network. -Helps to establish low latency communication.

choose TCP if you need reliable, sequence transmission, data integrity.
choose UDP if you need low latency, low overhead, less processing.

IP protocol:
Establishes communication for devices over internet and ensures that data reaches the correct destination using unique set of number known as ip address.
IP address for source and destination.
Routing tables to direct data from source and destination.

IPv4 - It is an internet protocol used to identify devices. It provides a unique 32-bit address for each device. Used for routing data between devices on local networks and across the internet.

IPv6 - It is an internet protocol with a 128-bit address and hexa-decimal format separated by colon(:). Includes built-in security features such as IPsec for encryption and authentication.

Ports:

Ports are communication endpoints that allow different services on a device to send and recieve data.

Subnetting:

It is a technique to divide a larger IP network into smaller, more manageable sub-networks.
Class A: 8-bit network ID, 24-bit host ID.
Class B: 16-bit network ID, 16-bit host ID.
Class C: 24-bit network ID, 8-bit host ID.

CIDR: Classless Inter Domain Routing.
A method for allocating IP address
10.0.0.0/24
10.0.0.0 - IP address
24 - subnet mask(represents how many bits can change in ip)
allocates 256 ips

Routing:

It is the process of path selection in any network(best path for communication is choosen)

• Routing creates efficiency
• Path determination
• Data forwarding
• Load balancing Types of routing:
• Static routing: In this type of routing the routing table is updated by the network administrator manually and routing decisions are not based on topology or condition of network.
• Dynamic routing: In this type of routing the routing table is automatically updated using routing protocols. In response to changes in condition or topology of network, router adds a new route in the routing table.

Domain Name System(DNS):

It translates human readable domain names to machine readable IP address.helps find mail servers, balances web traffic among
servers, redirects requests, performs reverse lookups, and speeds up responses through caching.

Virtual Private Network(VPN):

A secure tunnel to your internet connection

• A strong security protocol
• you get to control who sees what you're doing
• Work regardless of location
• Limitless internet
• A smoother connection VPN encrypts your data and routes it through a server.

Networking Tools

1. Ping: To check if a host is reachable or not
   • Example: ping example.com
2. Traceroute: Traces the path that data takes from one device to another across the network.
   • Example: traceroute example.com
3. ifconfig: Displays or configures network interface settings on a device.
   • Example: ifconfig
4. Netstat: To display active network connections, routing tables etc
   • Example: netstat -a
5. Nmap: A network scanning tool used to discover hosts and services on a network.
   • Example: nmap -p 1-1000 target
6. iperf: Measures network bandwidth between two devices.
   • Example: iperf -s(server) , iperf -c (client)

7. wireshark: A network protocol analyzer that captures and inspects network traffic in real-time

8. host: To query DNS servers about domain info.

   • Example: host example.com

9. tcpdump: A command-line packet analyzer used to capture and analyze network traffic.

10. dig(domain information groper): To query DNS servers about host addresses, mail exchanges etc

    • Example: dig example.com