INTERACTIVE NETWORK LESSONS · 39 PROTOCOLS · 8 LANGUAGES
Protocol Explorer is a free interactive learning tool that shows how the internet actually works. Instead of dry diagrams, every lesson animates real packets travelling between your laptop, the router, the ISP and servers across the internet — then decodes each one, byte by byte, exactly the way Wireshark would.
Each protocol follows the same calm, step-by-step flow: press play, watch the packet move across the network map, follow the handshake in the packet list, then open the inspector to see every header field and hex byte light up in place. A short tutorial explains what just happened and why the protocol was designed that way.
The HTTP and HTTPS lessons are free forever. A single one-time payment of $5 unlocks all 39 protocol lessons for life — no subscription, no renewal.
EXAM MODE · 204 SCENARIOS · 39 PROTOCOLS
After watching a lesson, switch from observing to building. Protocol Explorer exam mode gives you 204 scenarios across all 39 protocols: draw the messages, connect the devices, and check whether you can reconstruct the exchange yourself.
Choose the message types, connect senders to receivers, and arrange the conversation in order.
Switch to network topology to draw the device connections. Both views share the same answer.
Get a score with missing connections and ordering mistakes explained, replay the reference, and return to the matching lesson step.
HTTP and HTTPS exams are free. The existing one-time $5 unlock includes lessons and exams for all 39 protocols.
The explorer above is a complete network simulation environment. A network diagram shows every device on the path; packets animate along the wires in real time while a packet list records each exchange like a capture file. A sequence diagram view summarizes the whole conversation, and clicking any packet opens a full inspector with a decoded protocol tree and the raw hex dump.
Lessons cover the whole stack, from Ethernet frames and Wi-Fi handshakes at the bottom to HTTP requests, TLS sessions, SIP calls and WebRTC media at the top. Whether you are preparing for a certification or just curious what happens when you press Enter in the address bar, there is a lesson that shows it — literally.
Choose from 39 lessons grouped by layer: application protocols like HTTP, SMTP and IMAP; core protocols like TCP, UDP, IP and BGP; security protocols like TLS, WPA3 and WireGuard. Your progress is tracked for every lesson.
Each step of the tutorial animates the real exchange: a DNS lookup before the HTTP request, the TCP three-way handshake, the TLS ClientHello and ServerHello, the encrypted request and the response. Speed controls, step-by-step mode and keyboard shortcuts let you learn at your own pace.
Click any packet to open the inspector. Every header field is decoded and explained — source and destination addresses, ports, sequence numbers, flags, TLS extensions — and the hex view highlights the exact bytes each field occupies on the wire.
Progress bars show how much of each lesson and of the whole catalog you have completed, in any of the eight supported languages. Come back any time; everything is saved in your browser.
Every lesson follows the identical tutorial format, so once you learn the layout you can explore the whole catalog. Some of the most popular lessons:
Beyond those: WebSocket, WebRTC, SIP, RTSP, RTMP, UDP, IP, IPv6, BGP, DHCP, ICMP, IGMP multicast, NTP, DNS over HTTPS, DNSSEC, Ethernet, PPPoE, Wi-Fi, WPA3, RADIUS and 802.1X, captive portals, SMTP, POP3, IMAP, FTP, SMB, SSH, proxies, SOCKS5, reverse proxies, WireGuard, IPsec and Modbus. New protocols are added regularly.
Every lesson is a playable animation: packets travel the network, hop by hop, with the current step explained in plain language. Play, pause, step and scrub through the entire conversation.
Not a toy: each packet is a faithful, realistic example of the protocol on the wire, with a full decode tree and a synchronized hex dump — the same material you would study from a real capture.
The interface and all tutorials are available in English, French, Spanish, Brazilian Portuguese, German, Japanese, Korean and Traditional Chinese. Switch language at any time; your lesson progress follows you.
Move from watching packets to reconstructing the conversation. Protocol Explorer combines sequence diagrams and network topology in one graded exercise, with local drafts and account-saved results when you sign in.
Studying for the CCNA, Network+ or a university networking course? Reading about the TCP handshake is one thing — watching the sequence numbers tick up while each flag lights up is another. The byte-level inspector turns abstract header diagrams into something you have literally seen.
Debugging why a connection stalls, what a proxy does to a request, or what exactly happens during a TLS renegotiation? The lessons model the real exchanges — including tricky cases like TCP retransmission, TLS session resumption and DNS over HTTPS — so you build an accurate mental model you can debug against.
Preparing a networking lecture, brushing up before a system-design interview, or just wondering what happens when you open a website? Each lesson is self-contained, takes minutes, and works equally well on a laptop or a phone.
Three lessons people start with:
If you are just getting started, these in-page tools and lessons are the fastest next steps.
Scroll back up, press play, and watch your first packet travel the network. HTTP and HTTPS are free — the other 39 lessons are a one-time $5.
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