As soon I started learning about Cyber Security, the first thing I got into is to learn about Computer Networking, as much possible. The more you understand how Internet works, how the web applications function, the more you can dig deeper in search of loopholes, and can contribute to make cyberspace more secure.
Here I will be giving you an overview of the important topics in Networking, you can explore much more to get friendly with it.
What is a Computer Network ?
A computer network is a digital telecommunication network for sharing resources between nodes,which are computing devices that use a common telecommunication technology.
What is a Server ?
A server is a computer program or a device that provides functionality for other programs or devices called clients.
What is a Client ?
A Client is a piece of computer hardware or software that accesses a service made available by a server.
Protocol :
Set of rules defined for communication between devices.
Port :
A port in computer networking is a logical access channel for communication between two devices.
Example :
HTTP: Hypertext Transfer Protocol uses Port 80
HTTPS: Hypertext Transfer Protocol uses Port 443
FTP: File Transfer Protocol use port 21 (and 20)
Sockets :
A socket is the combination of IP address + Port. The server creates a socket, attaches it to a network port addresses then waits for the client to contact it. The client creates a socket and then attempts to connect to the server socket. When the connection is established, transfer of data takes place. IP Address : An IP address is a unique address that identifies a device on the internet or a local network.
Client Server Model :
It’s basically the client requesting something and the Server serving it as long as its present in the database.
How the browser interacts with the servers ?
User enters the URL(Uniform Resource Locator) of the website or file.
The Browser then requests the DNS(DOMAIN NAME SYSTEM) Server.
DNS Server lookup for the address of the WEB Server.
DNS Server responds with the IP address of the WEB Server.
Browser sends over an HTTP/HTTPS request to WEB Server’s IP (provided by DNS server).
Server sends over the necessary files of the website.
Browser then renders the files and the website is displayed. This rendering is done with the help of DOM (Document Object Model) interpreter, CSS interpreter and JS Engine collectively known as the JIT or (Just in Time) Compilers.
Networking Devices :
Repeater :
A repeater is an electronic device that receives a signal and retransmits it. Repeaters are used to extend transimssions so that the signal can cover longer distances or be received on the other side of an obstruction.
Hub :
A hub is multi-port repeater. It does not reads or understands the frames received.
Switch :
Switch reads frames received, and forwards to the only designated port.
Bridge :
An intermediatary device between hub & switches.
Bridge learns MAC addresses in software.
Switch learns MAC addresses much more quickly by using hardware ASICs(Application Specific Integrated Circuits)
Routers :
It allows us to route from one IP network to another.
Firewalls : It is a network security device that monitors traffic to or from your network. It allows or blocks traffic based on a defined set of rules.
IDS(Intrusion Detection System) : It is a system that monitors network traffic for suspicious activity and issues alerts when such activity is observed.
IPS(Intrustion Prevention System) : It is a network security device that monitors the traffic for suspicious activity, collect information about the activity, report it and attempt to block or stop it.
In the next article, I will be talking about TCP/IP Model.
Thanks.
