Full Cybersecurity Course From 0: Ethical Hacking & Defense

Build a solid foundation in computer networking with the OSI model, protocols, cryptography, and essential terms and commands through engaging animations.

Explore what a computer network is, why devices connect, and how resource sharing enables internet access, printers, and files to be shared across wired and wireless networks.

Learn what a local area network (LAN) is, how it enables data communication and resource sharing, and differences between wired Ethernet LANs and wireless WLANs for home and small businesses.

Explore wide area networks, the largest networks interconnecting geographically dispersed LANs, with the internet as a WAN example. Enterprises deploy private WANs to securely connect offices.

Explain pan as a personal area network for short-range device communication, typically 10 to 25 meters, using Bluetooth or USB, and define can as a campus area network unifying LANs.

Define a packet as a small segment of a larger file that is divided, transmitted independently, and reassembled at the destination, with a 1500-byte limit (9000-byte jumbo frames).

Discover how an IP address uniquely identifies devices on the internet, compare IPv4 and IPv6, and learn to view your own IP address using cmd ipconfig /all.

Learn what a server is—a computer configured to provide services—and explore common types like web, mail, file, database, and DNS servers, plus basic setup steps.

Learn how a client initiates requests to a server in the client-server model, and what a client application is, with examples like Firefox, Chrome, and Google.

Identify what an internet service provider is and how it delivers home connectivity. Explore broadband types such as cable, DSL, fiber optics, and satellites, including Starlink, and understand ISP installation.

Explain ethernet cables and RJ45 connectors that create wired connections, linking computers to switches and routers to access resources, and show how to locate LAN port for a wired connection.

Explore how the network interface card, or NIC, enables wired and wireless connectivity via Ethernet LAN ports and Wi‑Fi adapters.

Discover how a hub enables connectivity by linking devices with an Ethernet cable to form a LAN, broadcasting packets to all ports, with only the destination accepting them by MAC.

Explore how routers connect LANs to the internet by routing packets using IP addresses (and MAC basics), and differentiate wireless and wired routers with a built in switch.

Understand how a modem converts analog internet signals to digital, connects your home to your ISP, and how a router distributes that access via LAN and WAN ports or Wi-Fi.

Learn how a repeater regenerates weak wireless and wired signals to extend network coverage. Understand attenuation and how repeaters boost signals to improve connection on distant devices.

Discover how a wireless access point extends wifi coverage by linking to a wired router with an ethernet cable, and how it differs from a wireless router.

Explore bus topology, a shared cable network with drop lines, taps, and terminators, where devices communicate via a single backbone and experience signal reflection and limited scalability.

Explore the star topology, where devices connect to a central switch via an Ethernet cable and data flows through the switch, highlighting security, fault tolerance, and central device failure risk.

Explore mesh topology, where each device directly connects to others, creating multiple routes for data and fault-tolerant delivery suitable for internet-scale networks.

Explore wireless topologies—infrastructure, wireless mesh, and ad hoc—showing how devices connect to a network via wifi or bluetooth and how wireless mesh offers reliable, failure-tolerant connectivity without wiring.

Explore the OSI model and its seven layers, from data preparation to delivery across networks, and learn how this layered approach enables troubleshooting and error isolation.

Explore how the application layer provides protocols like http, https, smtp, and ftp to support network applications such as browsers and emails. Network applications rely on these protocols to function.

The session layer manages sessions, authentication, authorization, and checkpoints to resume data exchange across devices. It assigns unique session IDs and maintains multiple concurrent sessions, terminating when you log out.

The transport layer breaks data from the session layer into segments, assigns sequence numbers, and enables process-to-process delivery via source and destination ports, then reassembles packets into the original file.

Understand how the transport layer regulates data flow with window size and ensures error-free delivery using checksums and ARQ. Compare TCP's reliable, connection-oriented delivery with UDP's fast, unreliable data transmission.

The network layer delivers host-to-host data by converting transport segments into packets, assigning source and destination IP addresses, routing through routers, and handling fragmentation for MTU limits.

Learn how the data link layer delivers data node to node, controls flow and errors, framing, and uses mac addresses and csma/cd to prevent collisions with switches.

Explore how the physical layer converts digital bits into electrical or optical signals and transmits them over cables, optical fibers, or radio waves, while the data link layer prepares data.

Understand how the TCP/IP model, built on the Transmission Control Protocol and Internet Protocol, powers internet communication and why the OSI model is a prerequisite.

Compare old and updated tcp/ip models, noting the internet layer renamed to network, the link layer split into data link and physical, and the first three layers merged into application.

Explore why the OSI model remains essential for understanding data communication and troubleshooting, even though the TCP/IP model merges its layers into the application layer.

Learn the updated tcp/ip model and how its application, transport, network, data link, and physical layers handle data as segments, packets, frames, and bits, with osi similarities.

Learn how the Dynamic Host Configuration Protocol assigns IP addresses automatically, compare manual versus automatic assignment, and how routers can act as DHCP servers for scalable networks.

Learn how a DHCP client requests an IP address from a DHCP server, and how routers typically act as the DHCP server to manage IP allocation.

Explore the Dora process in DHCP, showing how a client broadcasts discover, receives an offer, sends a request, and obtains an acknowledgement to obtain an IP address and default gateway.

Discover how the ARP protocol maps IP addresses to MAC addresses, enabling data exchange by finding the receiver's MAC via broadcast and storing mappings in the ARP table and cache.

Explore what DNS is and why it matters, showing how domain names are translated into IP addresses to let your browser access websites behind the scenes.

Learn to view a website's IP addresses using PowerShell and the resolve-dns name command, which returns IPv4 and IPv6 addresses.

Explore the fundamentals of cryptography and its role in securing data across networks, explaining how encryption protects messages from interceptors and how decryption reveals original data at the destination.

Clarify cryptography terms, including encryption, decryption, and the difference between encryption and cryptography. Explain how encryption protects data from unauthorized access and how decryption restores the original message.

Explore symmetric encryption, using the same secret key to encrypt and decrypt data, explain methods like Caesar cipher and algorithms such as AES, and cover secure key exchange via Diffie-Hellman.

Explains asymmetric encryption using public and private keys to encrypt with the recipient's public key and decrypt with the corresponding private key, solving the key sharing problem.

Explore the most common encryption algorithms, including AES (advanced encryption standard) as a symmetric standard, RSA as a public key algorithm, and Triple DES, along with DES, Blowfish, and Twofish.

Learn how key length shapes encryption security, from 128 to 512 bit keys, and why longer keys dramatically increase resistance to brute-force attacks.

Explore the basic structure of hashing functions and compare md5 with the sha family, including md5’s 128-bit output and sha variants of 160, 256, and 512 bits expressed in hex.