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Networking

Networking Fundamentals — Zero to Advanced

From what a packet is to subnetting, routing, DNS, TCP, firewalls, and Wireshark — 20 modules, no prerequisites

Self-paced May 2026
🎓Complete beginners — no networking knowledge needed
🔐Security learners who need networking foundations
💼Anyone preparing for CompTIA Network+ or Security+
🖧Developers who want to understand what their code runs on
44
Modules
5
Sections
364+
Topics covered
16h
Total content
100%
Free forever
This course builds the networking foundation every security professional needs. You will understand how packets move from your keyboard to a server on the other side of the planet — every hop, every protocol, every layer. Module 01 assumes zero prior knowledge. Module 20 covers tools used by network engineers and penetration testers every day.
What makes this different
◎
Built for Security
Every protocol is taught alongside how attackers abuse it — so you understand defence, not just theory.
▶
Real Commands
Wireshark captures, tcpdump filters, nmap scans — commands you run on your own machine as you read.
⊞
Packet-Level Diagrams
Every major protocol is shown as actual bytes — so the OSI model becomes concrete, not abstract.
≡
No Fluff
No "send us your email for a certificate". Just the concepts, explained clearly, from first principles to advanced.
→
Recommended next course after this one
Once you have finished all 20 modules here, you have the networking foundation needed for the Cybersecurity course.
Cybersecurity — Zero to Hired →
// Curriculum

20 Modules. Packets to Penetration Testing.

Follow in order. Each module builds on the last. Module 01 assumes you know nothing — Module 20 ends with tools used by professional network engineers and security researchers.

1
Section 1 — How Networks Work
MODULE 01✓ LIVE

What is a Network?

Packets, nodes, protocols — and what actually happens when you press Enter in a browser

PacketsNodesClients & serversProtocolsWhy networks exist
⏱ 18–24 min
Beginner
Start →
MODULE 02✓ LIVE

Network Types and Topologies

LAN, WAN, MAN — and why the physical layout of your network determines what can go wrong

LANWANMANStarMeshBusRingHybrid
⏱ 20–26 min
Beginner
Start →
MODULE 03✓ LIVE

The OSI Model — All 7 Layers

The universal framework every engineer uses to reason about networking problems

OSIPhysicalData LinkNetworkTransportSessionPresentationApplication
⏱ 22–30 min
Beginner
Start →
MODULE 04✓ LIVE

The TCP/IP Model — How the Internet Works

The four-layer model that actually runs the internet — full packet walk-through from click to server

TCP/IPLink layerInternet layerTransport layerApplication layerEncapsulation
⏱ 20–26 min
Beginner
Start →
MODULE 05✓ LIVE

Data Transmission — Signals, Bandwidth, and Latency

How bits travel as electrical signals, light, and radio waves — and why latency kills more apps than bandwidth

BandwidthLatencyThroughputJitterAnalog vs digitalEncodingNoise
⏱ 16–22 min
Beginner
Start →
MODULE 06✓ LIVE

Binary and Hexadecimal for Network Engineers

The two number systems that appear in every IP address, MAC address, and packet capture

BinaryHexadecimalDecimal conversionBits & bytesNibblesWhy networking uses hex
⏱ 14–20 min
Beginner
Start →
2
Section 2 — Physical and Data Link Layer
MODULE 07✓ LIVE

Cables, Connectors, and Physical Media

Cat5e vs Cat6A vs fiber — and why the cable you choose determines your ceiling

Cat5eCat6Cat6AFiberCoaxialRJ-45SFPPoETIA-568
⏱ 16–22 min
Beginner
Start →
MODULE 08✓ LIVE

Ethernet, Switches, and MAC Addresses

How devices on the same network find and talk to each other — frames, CAM tables, full duplex

EthernetFramesMAC addressSwitchCAM tableCSMA/CDFull duplexCollision domain
⏱ 20–26 min
Beginner
Start →
MODULE 09✓ LIVE

ARP — How IP Maps to MAC

The protocol that bridges Layer 3 addresses to Layer 2 — and how attackers exploit it

ARPARP cacheARP requestARP replyGratuitous ARPARP spoofingARP poisoning
⏱ 16–22 min
Beginner
Start →
MODULE 10✓ LIVE

VLANs — Network Segmentation Without Hardware

802.1Q tagging, trunk ports, inter-VLAN routing — and why VLANs are the first line of internal defence

VLAN802.1QTrunkAccess portNative VLANInter-VLAN routingVLAN hopping
⏱ 18–24 min
Beginner
Start →
MODULE 11✓ LIVE

Spanning Tree Protocol — Preventing Broadcast Storms

How STP stops switch loops from bringing down your entire network in under 1 second

STPRSTPRoot bridgePort statesBroadcast stormBPDUConvergencePVST
⏱ 18–24 min
Beginner
Start →
MODULE 12✓ LIVE

Wi-Fi — 802.11 Standards, WPA2, WPA3

2.4GHz vs 5GHz vs 6GHz, channel overlap, WPA3-SAE, and every way wireless gets attacked

802.11acWi-Fi 6WPA3SSIDChannelCSMA/CAEvil twinDeauthPMKID
⏱ 20–28 min
Beginner
Start →
3
Section 3 — The IP Layer — Addressing and Routing
MODULE 13✓ LIVE

IPv4 Addressing — Complete Guide

Public vs private, RFC 1918, CIDR notation, address anatomy — everything about the 32-bit address that finds every device

IPv432-bitDotted decimalPublic IPPrivate IPRFC 1918CIDRAddress classes
⏱ 18–26 min
Intermediate
Start →
MODULE 14✓ LIVE

Subnetting — Divide Any Network with Confidence

Subnet masks, network ID, host range, broadcast — the skill every network interview tests

Subnet maskNetwork IDHost rangeBroadcastCIDR/24/16/30VLSMFLSM
⏱ 24–32 min
Intermediate
Start →
MODULE 15✓ LIVE

IPv6 — The Protocol That Replaces IPv4

128-bit addressing, EUI-64, SLAAC, link-local, dual stack — and why you will manage both for the next decade

IPv6128-bitEUI-64SLAACLink-localGlobal unicastDual stackNDPDHCPv6
⏱ 18–26 min
Intermediate
Start →
MODULE 16✓ LIVE

Routing — How Packets Find Their Destination

Routing tables, default gateway, longest prefix match, TTL, how every hop decision is made

Routing tableDefault gatewayLongest prefix matchTTLHopStatic routeNext hop
⏱ 18–24 min
Intermediate
Start →
MODULE 17✓ LIVE

Dynamic Routing — OSPF, EIGRP, BGP

How routers learn paths automatically — link-state vs distance-vector, AS numbers, BGP hijacking

OSPFBGPEIGRPRIPLink-stateDistance-vectorAS numberBGP hijackingRoute redistribution
⏱ 20–28 min
Intermediate
Start →
MODULE 18✓ LIVE

NAT and DHCP — How Private Networks Work

How 4 billion private IPs share the internet — port mapping, DORA, lease times, starvation attacks

NATPATSNATDNATDHCPDORAIP leaseDHCP starvationAPIPA
⏱ 18–24 min
Intermediate
Start →
MODULE 19✓ LIVE

ICMP — Ping, Traceroute, and Error Messages

The control plane of IP — how ping works at the packet level, traceroute TTL trick, ICMP tunneling

ICMPPingTracerouteTTL exceededEcho requestEcho replyICMP tunnelingMTU discovery
⏱ 14–20 min
Intermediate
Start →
4
Section 4 — Transport Layer
MODULE 20✓ LIVE

TCP — The Protocol That Guarantees Delivery

3-way handshake byte by byte, sequence numbers, flow control, congestion control, FIN vs RST

TCPSYNACK3-way handshakeSequence numbersFlow controlCongestion controlRSTFIN
⏱ 22–30 min
Intermediate
Start →
MODULE 21✓ LIVE

UDP — When Speed Matters More Than Reliability

DNS, video, gaming, QUIC — why connectionless is the right choice more often than you think

UDPDatagramConnectionlessDNSVoIPGamingUDP floodAmplification attack
⏱ 14–20 min
Intermediate
Start →
MODULE 22✓ LIVE

Ports and Sockets — Where Applications Live

Well-known ports, ephemeral ports, socket pairs, how an OS routes packets to the right process

PortsSocketsWell-known portsEphemeral portsSocket pairnetstatssTCP states
⏱ 16–22 min
Intermediate
Start →
MODULE 23✓ LIVE

TLS — How Encryption Protects Every HTTPS Request

Certificate chain, handshake byte by byte, cipher suites, HSTS, certificate pinning, TLS 1.3 vs 1.2

TLSSSLCertificateCAHandshakeCipher suiteHSTSSNIPerfect forward secrecyTLS 1.3
⏱ 22–30 min
Intermediate
Start →
MODULE 24✓ LIVE

QUIC and HTTP/3 — The Future of Web Transport

How Google replaced TCP+TLS for web traffic — 0-RTT, stream multiplexing, connection migration

QUICHTTP/30-RTTMultiplexingHead-of-line blockingConnection migrationUDP-based
⏱ 14–20 min
Intermediate
Start →
5
Section 5 — Application Layer Protocols
MODULE 25✓ LIVE

DNS — How Domain Names Become IP Addresses

Recursive resolution step by step, all record types, zone transfers, cache poisoning, DNS over HTTPS

DNSA recordMXCNAMETXTSOANSRecursive resolverDNSSECCache poisoningDoH
⏱ 22–30 min
Intermediate
Start →
MODULE 26✓ LIVE

HTTP and HTTPS — The Protocol Powering the Web

Request-response lifecycle, all headers, methods, status codes, cookies, HTTP/2 multiplexing

HTTPHTTPSGETPOSTPUTDELETEStatus codesHeadersCookiesHTTP/2Keep-alive
⏱ 22–30 min
Intermediate
Start →
MODULE 27✓ LIVE

Email Protocols — SMTP, IMAP, POP3, SPF, DKIM, DMARC

How email actually travels from sender to inbox — and the three records that stop spoofing

SMTPIMAPPOP3SPFDKIMDMARCMX recordPhishing infrastructureEmail headers
⏱ 18–26 min
Intermediate
Start →
MODULE 28✓ LIVE

SSH — Secure Shell Complete Guide

How SSH key exchange works, agent forwarding, tunneling, ProxyJump — and every hardening step

SSHRSAEd25519Key exchangeAgent forwardingTunnelingProxyJumpsshd_configHardening
⏱ 20–28 min
Intermediate
Start →
MODULE 29✓ LIVE

FTP, SFTP, and Secure File Transfer

Active vs passive mode, why FTP is dangerous, SFTP vs FTPS vs SCP, real-world file transfer

FTPSFTPFTPSSCPActive modePassive modeCredentials in cleartextrsync
⏱ 14–20 min
Intermediate
Start →
MODULE 30✓ LIVE

DHCP Deep Dive — Address Assignment Under the Hood

DORA byte by byte, option 43, relay agents, rogue DHCP servers, starvation and spoofing attacks

DHCPDORADiscoverOfferRequestACKOption 53Relay agentRogue DHCPStarvation
⏱ 16–22 min
Intermediate
Start →
MODULE 31✓ LIVE

SNMP and Syslog — How Networks Are Monitored

MIB, OID, traps, community strings — and why SNMPv1 is a security disaster still running in 2026

SNMPSNMPv3MIBOIDTrapCommunity stringSyslogSeverity levelsLog aggregation
⏱ 14–20 min
Intermediate
Start →
MODULE 32✓ LIVE

NTP — Why Clock Synchronisation Is a Security Issue

Stratum levels, how NTP works, why wrong clocks break TLS certificates and Kerberos authentication

NTPStratumClock driftNTP amplificationAuthenticated NTPKerberos time window
⏱ 12–16 min
Intermediate
Start →
6
Section 6 — Network Security
MODULE 33✓ LIVE

Network Attacks — ARP Poisoning, MITM, Sniffing

Every Layer 2 and Layer 3 attack — how they work, what they look like in Wireshark, how to defend

ARP poisoningMITMMAC floodingVLAN hoppingSniffingPassive vs activeEttercapResponder
⏱ 22–30 min
Advanced
Start →
MODULE 34✓ LIVE

Firewalls, ACLs, and Stateful Inspection

Stateless vs stateful vs NGFW, ACL rule order, DMZ design, common bypass techniques

Stateless firewallStateful firewallNGFWACLDMZRule orderNAT firewallBypass
⏱ 20–28 min
Advanced
Start →
MODULE 35✓ LIVE

IDS and IPS — Detecting Attacks on the Wire

Signature vs anomaly detection, Snort/Suricata rules, inline vs passive, evasion techniques

IDSIPSSnortSuricataSignatureAnomalyInlinePassiveFalse positiveEvasion
⏱ 18–26 min
Advanced
Start →
MODULE 36✓ LIVE

VPNs and Tunneling — IPSec, SSL, WireGuard

How VPNs encrypt and encapsulate traffic — IKEv2, OpenVPN, WireGuard compared byte by byte

VPNIPSecIKEv2OpenVPNWireGuardTunnel modeTransport modeSplit tunnelingGRE
⏱ 20–28 min
Advanced
Start →
MODULE 37✓ LIVE

Wireless Security — WPA2/WPA3 Attacks

KRACK, PMKID attack, deauth frames, evil twin AP, rogue AP detection — complete wireless attack surface

WPA2WPA3KRACKPMKID4-way handshakeDeauthEvil twinaircrack-nghcxtools
⏱ 20–28 min
Advanced
Start →
MODULE 38✓ LIVE

Zero Trust Networking — Never Trust, Always Verify

BeyondCorp, microsegmentation, identity-based perimeter, ZTNA vs VPN — the architecture replacing VPNs

Zero trustBeyondCorpMicrosegmentationZTNAIdentity perimeterSDPSASEmTLS
⏱ 16–22 min
Advanced
Start →
MODULE 39✓ LIVE

DDoS — How It Works and How to Defend Against It

Volumetric, protocol, application layer — Cloudflare, AWS Shield, anycast — real attack breakdowns

DDoSVolumetricSYN floodHTTP floodAmplificationCloudflareBGP anycastRate limiting
⏱ 18–24 min
Advanced
Start →
7
Section 7 — Tools and Troubleshooting
MODULE 40✓ LIVE

Network Troubleshooting Methodology

The OSI-layer-by-layer methodology that resolves 90% of issues — with every command you run at each step

Troubleshootingpingtraceroutenslookupnetstatssip routearp -aMethodology
⏱ 18–24 min
Advanced
Start →
MODULE 41✓ LIVE

Wireshark — Packet Analysis Complete Guide

Capture filters, display filters, following streams, decrypting TLS, real-world pcap analysis

WiresharkCapture filterDisplay filterTCP streampcapDecrypting TLSProtocol dissector
⏱ 22–30 min
Advanced
Start →
MODULE 42✓ LIVE

tcpdump — Command-Line Packet Capture

BPF filter syntax, writing pcaps, piping to Wireshark — the tool every Linux engineer needs

tcpdumpBPFCapture filterpcap-w flag-r flagExpressionsRemote capture
⏱ 16–22 min
Advanced
Start →
MODULE 43✓ LIVE

Nmap — Network Scanning and Host Discovery

SYN scan, OS fingerprinting, NSE scripts, timing, evading firewalls — complete offensive and defensive use

NmapSYN scan-sV-ONSETimingFirewall evasionHost discoveryPort states
⏱ 20–28 min
Advanced
Start →
MODULE 44✓ LIVE

Network Monitoring — NetFlow, SNMP Polling, Dashboards

How enterprise networks are observed at scale — NetFlow, SNMP polling, Grafana, alerting

NetFlowsFlowSNMP pollingGrafanaPrometheusAlertmanagerBandwidth monitoringNOC
⏱ 16–22 min
Advanced
Start →
Ready to go deeper?

After completing this course, the Cybersecurity track picks up exactly where you leave off — using these networking fundamentals to understand attacks, defences, and professional security work.

Start Cybersecurity Course →
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