Computer Networking & Networking Concepts
A network is a collection of computers and other technological devices that are linked in one way or the other for communication and transmission of data and sharing of other resources.
Networking concepts are technologies, topologies, hard and software equipment and protocols which are essential in networking within the home or close-range networks and across the internet.
Some Networking Concepts
Hosts
Hosts are independent systems or machines that are connected or communicating within the same network. A host can either be served as a client or as a server or serving the same purpose at a time.
Packet
A packet is a broken unit of data that is to be sent within and outside a network. The computer or other device that receives these packets then reassembles them.
Router
The router is a hardware or software, a virtual internetworking component used to receive, examine, and transmit data packets between computers, routed mostly within a local network and serving as a gateway for external connection. Routers are like instruments that enable computers to talk to each other within a network by assigning a uniform IP range to these computers.
The router has both an internal IP or private address for shared communication with devices within its network, the routing devices in the local network also have private IP addresses mapped from the router's private IP address and an external IP or public address for communication with other devices across the internet. This public address is uniquely provided by the ISP. In any case, where any of the devices within the local network wants to communicate with other devices over the internet, the internal device does this through the router.
Routing Table
Routing Table determines the set of rules of how data packets move across a network Protocol. The routing table stores the location of routers based on their IP addresses in a table or database. The RAM of the majority of routers or forwarding devices often houses this database, which serves as an address map to multiple networks. As a result, a routing table contains details about numerous networks and instructions to reach them.
When a router receives information or a packet, it forwards that packet to either another host on the network or an entirely new network like the internet. To do this, it looks at the destination of the IP address and checks the routing rules that are mapped in the routing table to find one of the rules to follow in forwarding the packets.
Local Area Network(LAN)
LAN is a group of interconnected devices situated in a single building, workplace, or residence. A LAN can be tiny or big, with one user's home network or hundreds of users and devices in an office or school. The fact that a LAN connects devices that are located in a single, confined location is its sole distinctive feature, regardless of size. Different Local Area Networks can be connected to a Wide Area of a Metropolitan Area Network as the case may be.
Wireless Local Area Network (WLAN)
A wireless Local Area Network (WLAN) is a collection of closely spaced computers or other devices that are linked wirelessly rather than through wired connections to form a network.
Wide Area Network(WAN)
WAN is a vast network of data that is not confined to one location. Unlike the WLAN, a wide-area network has numerous locations dispersed across a particular geographic area, or possibly the entire world; it extends beyond a single building, local area networks, and a group of computers.
Internet Service Provider(ISP)
ISP is an organization that offers other organizations and individuals access to the internet and other internet-related services. These organizations have the license, tools and telecommunications lines necessary to maintain an online presence in all the regions they serve.
Wireless Fidelity(WiFi)
WiFi is a wireless networking technology that uses radio waves to speedily and easily connect computers, tablets, smartphones, and other devices to the internet. WiFi technology enables computers, smartphones, or other devices to access the internet or wirelessly communicate with one another within a specific location using radio waves to transmit information between the connecting devices and a router via frequencies.
Internet Protocol(IP)
Internet Protocol(IP) is an address that is uniquely assigned to a device or group of devices sharing a network over the internet. IP addresses use a collection of standards that control the format of how data is transmitted over a local or public network. These devices can communicate with one another and exchange data on a local network or the internet because of the IP address.
An IP address contains a series of numerals separated by dots to form four octets. These four octets represent a specific address altogether, and each one has a range of 0 to 255. A sample of an IP address is 178.01.14.20. There are two versions of IP address, the IPv4 is typical of what we outlined initially in this paragraph because it is what every device in the world uses today.
However, this IPv4 mapping is getting exhausted now due to its prominence. The IPv6 was introduced with an inexhaustible and unlimited IPv4 address to fill that gap. Both IP versions are now in use. To find out the IP address of your device, visit whatismyipaddress.com. This site will show the IP address together with the IPv6 address and some other information like your ISP, your country, region and city.
Media Access Control(MAC)
Media Access Control(MAC) address, 12-character alphanumeric information used to identify devices on a network, also known as a hardware or physical address. It serves both to uniquely identify certain electronic devices on a network as well as a network address in communications within a network segment.
The characters are divided into six segments two characters in each and separated by a hyphen(-). An example of a MAC address is 00-B0-D0-63-C2-26. The first three groups of numbers in a MAC address represent the manufacturer of the device while the last three groups are assigned by the manufacturer and its specific to the device. To find the manufacturer, name of the device and other information about the device, dnslookup/mac-lookup.php.
Address Resolution Protocol (ARP)
Address Resolution Protocol (ARP) is a protocol that establishes an association between IP and MAC address and stores their link on the arp cache. As a protocol, It translates a dynamic IP address to a permanent physical machine address(MAC address) in a local area network. ARP also helps the computer keep track of all the various associations it has with IP and MAC addresses.
A local area network (LAN) has two addresses for each device, one is constant (your IP address), and the other changes (your MAC address). Those two systems remain linked via ARP. How this works when a network gateway receives a piece of data that needs to connect to a LAN machine. ARP aids in ensuring the data is received at the proper location, in other words, this protocol makes communication within a network efficient.
Protocol
Protocols are rules that govern how information is sent and received. The protocol ensures that the information transmitted is sent to the actual service that needs it.
Transmission Control Protocol(TCP)
Transmission Control Protocol(TCP) is one of the two ways information is sent over a network. This protocol is used by computer hardware and communication software to exchange messages over networks. This protocol's job is to transport packets over the Internet and make sure that data and messages are successfully delivered across networks. TCP is connection-oriented, reliable, and checks if the message sent is in order and received by the recipient. Even though the transmission is slower, it is highly effective for sending data where time is of less relevance but requires high reliability and ensuring packets get to their destination.
TCP is connection based meaning that there must be an established communication between sender and receiver before the information can be sent. The protocol is known to require a three-way handshake - SYN, SYN-ACK and ACK.
SYN - During a communication, an initial request is made by the client to synchronize or request for a communication or file share with the server. Synchronize-Acknowledgement (SYN-ACK) - The server acknowledges the request to communicate while responding to the client's request with the information requested. The information is broken down into segments and is numbered sequentially. The client receives the information while sending back an SYN to the server in recognition of the information received.
The client and server must establish a connection before sending any data. Whenever a connection is made, the server must be actively watching for client requests. Because the TCP protocol is connection-based, a connection is established and maintained between the sender and the receiver while data is transferred between them. Any information that is transmitted via this protocol is reliable and therefore assured to arrive unchanged.
User Datagram Protocol (UDP)
This is the second of the two ways information can be sent over a network. UDP is good for sending information that requires speedy delivery due to its high latency. This protocol does not have any inherent checks to verify that all the packets will be received by the recipient, hence it is not reliable. This protocol unlike the TCP does not require a three-way handshake, it is connectionless and drops off information in any order.
File Transfer Protocol(FTP)
This is a set of guidelines that control how computers move files from one system to another via the internet. FTP is used by businesses to transfer files between computers, while websites utilize it to upload and download files from the servers that host their websites.
FTP operates by establishing two connections between the computers that are attempting to interact. The data transfer is handled by one channel, and the other is used for the orders and responses that are transmitted back and forth between the two clients. The communicating computers, servers, or proxy servers employ four commands during an FTP transaction - Send, Get, Change Directory and Transfer.
The Dynamic Host Configuration Protocol(DHCP)
DHCP is the process of giving client computers logging into an IP network IP addresses automatically. Despite being transitory, the same address can stay with a machine eternally if no other network devices are in issue. In other words, DHCP is a server that can automatically assign an IP address to a machine using the network protocol from a specified range of numbers set up for a specific network.
Simple Mail Transfer Protocol(SMTP)
SMTP is an Internet-standard protocol for transmitting electronic mail between email senders and recipients, mail servers employ the Simple Mail Transfer Protocol application.
Domain name System(DNS)
Domain name System is the structured and distributed naming system used to identify servers that may be accessed via the Internet or other Internet Protocol networks. The DNS converts human readable names like google.com into the numerical IP addresses that computers use to communicate with one another.
The DNS system on the Internet controls the mapping between names and numbers, much like a phone book. DNS servers which are broken into root name servers, Top-Level domains (TLD) and name servers query each other to provide the results a user needs when they enter a domain name into their web browser by converting requests for names into IP addresses. These DNS requests are referred to as queries.
Internet Control Message Protocol(ICMP)
ICMP is a network protocol which devices such as routers utilize in sending error-reporting signals back to the source IP address. One of the main purposes of ICMP is to check if data is reaching its destination at the appropriate time. Because of this, ICMP is key to the error reporting process and to measuring a network's data transmission efficiency.
If some of the data does not travel as expected when two devices are connected via the internet, ICMP can be used to cause errors regarding the data on travel from the transmitting device to the receiving device. This message protocol does not establish any connection, the notification is just transmitted without pointing to any specific port.
Hypertext Transfer Protocol(HTTP)
HTTP is a protocol used to load web pages via hypertext links. Running on top of other layers of the internet protocol suite, HTTP is an application layer protocol created to transport data between networked devices. A computer that is seeking a web page requests a server, the server then returns the web page in a normal HTTP flow.
Hypertext Transfer Protocol Secure(HTTPS). It is frequently used on the Internet to achieve more secure communication. This uses Transport Layer Security, also known as Secure Sockets to ensure that the communication protocol is encrypted.
Both HTTP/HTTPS make it simple for devices and web-based applications to communicate with one another, It outlines the format and the transmission of content requests as well as the composition of responses. They use TCP/IP models to transmit data such as text, pictures, audio, video, etc.
Ports
Ports are entry and exit points of information in a computer. Ports work together with IP addresses to ensure that information coming in and going out reaches the desired destination. There are 65,536 ports available in every computer divided into three categories, server ports running popular services, registered ports or software protocols, and private ports.
**Services **
Services are sets of programs running on a computer. These services may request data and information from another computer. Services may also require sending data or information out to another computer.
Firewall
A firewall is a network security feature that monitors traffic and either permits or blocks certain packets of data based on an already-established protocol or rule. This rule can be to public connection from a specific IP address. A firewall can also be used to block connections to a specific service using the port that such a service connects to. In Linux, these firewall rules can be controlled using the iptables command.
Iptable - this has three basic input chains that hold firewall rules. The first is INPUT - this chain holds rules involving the behaviour of incoming connections. The second if FORWARD - used to control the behaviour of incoming connections that aren't being locally but forwarded somewhere else. OUTPUT - this chain holds rules used to control the behaviour of outgoing connections.
Each rule has three basic responses for what to do with a specific connection. One is ACCEPT - this allows the connection. Two is DROP - this drops the connection like it never happened. The third is REJECT - this does not allow the message but sends back an error to the initiator.
**Network Address Translation(NAT) **
Network Address Translation is a process of changing the IP addresses as well as the port numbers. Its role is to convert one group of IP addresses into another group using Routers or firewalls. The NAT procedure improves security and aids in IP address preservation to serve the growing number of hosts and users connecting and communicating daily.
Ethernet
Ethernet is the standard technology for connecting devices in a local or wide area network (L/WAN) through physical wired cables while providing protocols, which act as a set of guidelines that allow devices to communicate with one another. Ethernet covers the formatting and transmission of data by network devices so that other systems connected to the same network can recognize, receive, and process the data.
Ethernet is most usually used by connected devices that connect via cables, as opposed to wifi networks, to access a geographically localized network.
Subnet
Subnetting is the process of splitting a network into two or more networks. Networks are more effective with subnets. Network communication can go a shorter distance to its destination without using extraneous routers thanks to subnetting. It improves network security by improving routing efficiency, while also decreasing the overall broadcast domain.
Open System Interconnection(OSI)
OSI model demonstrates the seven-tier operations through which a packet moves via a networking system and outlines the levels at which the computer system utilizes these operations to communicate over a network. The OSI model is broken into - Physical layer, Data link layer, Network layer, Transport layer, Session layer, Presentation also called translation layer and Application layer.
Transmission Control Protocol/Internet Protocol(TCP/IP)
The TCP/IP is an offshoot of the OSI model that details the actual implementation of computer networking. This protocol suite defines how data (packets) are gathered, broken down, addressed, routed and sent over a network to ensure that the recipient receives the same information that was initially sent, untampered.
The TCP/IP model breaks data into tiny packets and then integrates the packets into a whole message when it reaches the receiver in order to maintain accuracy between the data being transmitted and the original one. The TCP/IP model is broken into four layers - Physical, Data-Link, Network, Transport, and Application layer.