Introduction:
Computer networking is an essential aspect of modern technology that allows devices to communicate and exchange information over a network. In this article, we will discuss the basic concepts related to computer networking.
Open and Closed Systems:
A system that is connected to the network and is ready for communication is called an open system. On the other hand, a closed system is not connected to the network and cannot be communicated with Computer networks are an interconnection of multiple devices that communicate with each other through various protocols and network devices such as routers, switches, hubs, and bridges. The layout arrangement of these devices in a network is called the network topology, which can be classified into common types such as bus, star, mesh, ring, and daisy chain. To ensure standardization in communication protocols, the International Organization For Standardization developed the Open Systems Interconnection (OSI) reference model, which has 7 layers, each with specific functions and protocols. These protocols are essential to ensure seamless communication between different devices in the network. Additionally, each device in the network is associated with a unique device name known as a hostname and a unique identifier known as the IP address, which is the network address of the system across the network. A Media Access Control (MAC) address is also associated with each host and is a unique identifier of the host's NIC (Network Interface Card). Finally, a port is a logical channel through which data can be sent/received to an application, and a DNS server is used to translate web addresses or URLs into their corresponding IP addresses.
Computer Network:
A computer network is an interconnection of multiple devices or hosts that are connected using multiple paths for the purpose of sending and receiving data or media. Network devices, such as routers, switches, hubs, and bridges, help in the communication between two different devices.
Network Topology:
The layout or arrangement of the different devices in a network is known as network topology. Common examples include Bus, Star, Mesh, Ring, and Daisy chain.
OSI Model:
The OSI model is a reference model that specifies standards for communication protocols and functionalities of each layer. The OSI model has been developed by the International Organization for Standardization, and it consists of 7 layers. Each layer has different functions and protocols.
The 7 layers are:
Physical layer
Data link layer
Network layer
Transport layer
Session layer
Presentation layer
Application layer
Protocol:
A protocol is a set of rules or algorithms that define how two entities can communicate across the network. There are different protocols defined at each layer of the OSI model, such as TCP, IP, UDP, ARP, DHCP, FTP, and so on.
Unique Identifiers of Network:
Each device in the network is associated with a unique device name known as Hostname. To find the hostname of your machine, type "hostname" in the command prompt(Administrator Mode) and press ‘Enter’.
IP Address:
Also known as the Logical Address, the IP Address is the network address of the system across the network. The Internet Assigned Numbers Authority (IANA) assigns an IPV4 (Version 4) address as a unique identifier to each device on the Internet. The length of an IPv4 address is 32-bits, and the length of an IPv6 address is 128-bits. To find the IP address of the device, type "ipconfig" in the command prompt and press ‘Enter’.
MAC Address:
Also known as the physical address, the MAC Address is the unique identifier of each host and is associated with its NIC (Network Interface Card). A MAC address is assigned to the NIC at the time of manufacturing. The length of the MAC address is 12-nibble/ 6 bytes/ 48 bits. To find the MAC address, type "ipconfig/all" in the command prompt and press ‘Enter’.
Port:
A port can be referred to as a logical channel through which data can be sent/received to an application. Any host may have multiple applications running, and each of these applications is identified using the port number on which they are running. A port number is a 16-bit integer. We have 65,536 ports available, categorized as Well-known Ports (0 – 1023), Registered Ports (1024 – 49151), and Ephemeral Ports (49152 – 65535). To list all the ports being used, type "netstat -a" in the command prompt and press ‘Enter’.
Socket:
The unique combination of IP address and Port number together are termed as Socket.
Other Related Concepts:
DNS Server:
DNS stands for Domain Name system. It is a server that translates web addresses or URLs (ex: www.google.com) into their corresponding IP addresses. The command ‘nslookup’ gives you the IP address of the domain you are looking for and also provides information about your DNS server.
DHCP:
DHCP stands for Dynamic Host Configuration Protocol.
It is used to assign IP addresses dynamically to hosts in a network.
Instead of manually configuring each host with a unique IP address, DHCP allows hosts to request an IP address from a DHCP server, which then assigns an available IP address from a pool of addresses.
Gateway:
A gateway is a network node that acts as an entry point to another network.
It serves as a bridge between different networks and is responsible for routing data packets between them.
In a typical home network, the gateway is usually the router that connects the local network to the Internet.
Firewall:
A firewall is a network security system that monitors and controls incoming and outgoing network traffic based on predetermined security rules.
It serves as a barrier between a trusted internal network and an untrusted external network, such as the Internet.
Firewalls can be hardware-based or software-based and can be configured to allow or block specific types of traffic based on source/destination IP addresses, ports, protocols, and other criteria.
VPN:
VPN stands for Virtual Private Network.
It is a secure network connection that allows remote users to connect to a private network over the Internet.
A VPN uses encryption and other security mechanisms to ensure that data transmitted over the Internet is secure and private.
VPNs are commonly used by businesses to allow employees to access company resources from remote locations, but they are also used by individuals to access restricted content and protect their online privacy.
In conclusion, understanding the basics of computer networking is essential in today's connected world. From open and closed systems to network topologies and unique identifiers like IP addresses and MAC addresses, there are many fundamental concepts that form the foundation of computer networking. Additionally, protocols like TCP/IP, DHCP, and DNS are essential for facilitating communication between devices on a network, while network devices like routers, switches, and firewalls help to manage and secure network traffic.
