Learn networking and Linux the visual way.
Animated, step-by-step lessons that show — not just tell. Built for IT students, sysadmins, and the just-curious. Pace it yourself; nothing autoplays.
Animated interactive lessons for Linux and networking — TCP/IP, DNS, TLS, HTTP, chmod, process lifecycle, SSH key authentication, and more.What happens when you type a URL?
The most-asked tech interview question, animated end to end. Five chapters take you from keystroke to pixels: DNS resolution, TCP handshake, TLS handshake, HTTP exchange, and browser render. Step through at your own pace.
- 01DNS resolution
- 02TCP 3-way handshake
- 03TLS handshake
- 04HTTP request/response
- 05Browser render
tracks · structured study paths
Red Hat certification track
The full RHCSA (EX200) and RHCE (EX294) syllabus, organized by Red Hat's official course breakdown. RHEL-specific deep dive.
Linux+ certification track
The four exam domains of CompTIA's vendor-neutral Linux certification mapped to our lessons and tools. Distro-agnostic.
networking · 5 lessons
What happens when you type a URL?
The most-asked interview question, animated. Five chapters: DNS → TCP → TLS → HTTP → Render. Step through each at your own pace.
OSI / TCP-IP layers
A packet wrapped layer-by-layer, then unwrapped on the other side. Watch headers stack and peel off — OSI 7 and TCP/IP 4 side by side.
DNS deep dive
Beyond the basics: recursive vs iterative, cache layers, TTLs, glue records, and what `dig +trace` actually shows.
NAT and routing
How packets cross networks. Source NAT, destination NAT, conntrack, routing tables — visualized with real IPs.
Networking basics
Configure a Linux interface the modern RHEL way: NetworkManager, nmcli, a static IP with gateway and DNS, connection profiles, and layered troubleshooting. RHCSA-ready.
linux · 22 lessons
SELinux contexts
Why Apache can't read your file. Watch the policy engine decide — and learn the workflow for fixing denials. RHCSA-ready.
Linux boot process
From power button to login prompt. Every stage in the chain — UEFI, GRUB, kernel, initramfs, systemd — with the rescue moves that save you. RHCSA-ready.
LVM stacking
Layer-by-layer build of an LVM stack: disks → PVs → VG → LVs → filesystem. Then extend live and snapshot. RHCSA-ready.
systemd targets
How systemd organizes services with dependencies and targets. Visual dependency graph, target nesting, and the isolate trick. RHCSA-ready.
Command line essentials
Six animated chapters take you from 'what's that $ symbol?' to chaining commands with pipes. Live terminal transcripts as you step through. On-ramp for everything else.
File system hierarchy
Animated tour of every important top-level directory on Linux. /etc, /var, /usr, /home, /tmp, /proc, /dev — what they're for and what lives there.
Globbing and quoting
Wildcards (*, ?, [abc], {a,b}, **) and the three quoting styles. Six animated chapters showing what the shell rewrites BEFORE the command runs.
Local users and groups
Read /etc/passwd, /etc/shadow, and /etc/group field by field, then create, modify, lock, and delete accounts with useradd, usermod, passwd, and chage. RHCSA-ready.
SUID, SGID & sticky
The fourth octal digit explained. SUID (run as owner), SGID on files and dirs (group inheritance), and the sticky bit (shared-dir delete protection). RHCSA-ready.
Processes and signals
What a process really is, the five states (R/S/D/T/Z), job control, the signal catalog, kill vs kill -9, and nice/renice priority. RHCSA-ready.
Logs with journalctl
The systemd journal, demystified. Filter by unit, priority, and time; follow live logs; inspect previous boots; make logs persist. RHCSA-ready.
Access Control Lists (ACLs)
Fine-grained access beyond owner/group/other. getfacl, setfacl, named user/group entries, the mask, and inherited default ACLs on directories. RHCSA-ready.
Kernel parameters & tuned
Boot-time kernel cmdline (GRUB/grubby) vs runtime sysctl tunables, making each persist, and tuned profiles that bundle dozens of knobs. RHCSA-ready.
Swap space
Disk-backed safety net when RAM fills. Swap files vs partitions, mkswap/swapon, /etc/fstab, and the vm.swappiness tunable. RHCSA-ready.
Software with dnf/yum
Install/remove/upgrade with transaction previews, manage repos, pick module streams, and roll back any change with dnf history. RHCSA-ready.
Block devices & partitions
How Linux sees disks: lsblk, MBR vs GPT, parted, partition alignment, partprobe, and stable UUIDs via blkid. RHCSA-ready.
File systems & mounts
From bare partition to mounted, persistent filesystem. mkfs.xfs/ext4, mount options, /etc/fstab with UUIDs, fsck, and online growth. RHCSA-ready.
Stratis & VDO
Modern RHEL storage: Stratis thinly provisioned pools and filesystems with snapshots, and VDO inline dedupe/compression underneath. RHCSA-ready.
GRUB & rescue boot
When the system won't boot. GRUB cmdline editing, rd.break root-password reset, rescue/emergency targets, and persisting args with grubby. RHCSA-ready.
Podman containers
Daemonless, rootless containers on RHEL. pull/run/exec/logs, volumes with SELinux relabel, and persisting as systemd units via Quadlet. RHCSA-ready.
chmod, visualized
Click bits, watch them flip. See `rwx` ↔ `755` ↔ binary in lockstep. Includes setuid, sticky, and group inheritance.
Linux process lifecycle
fork, exec, wait, exit — animated. See how every program on Linux is born, runs, and dies.
security · 3 lessons
SELinux booleans
Runtime on/off switches that toggle whole chunks of policy — getsebool, setsebool -P, finding the right one, and the denial-fixing workflow. RHCSA-ready.
How SSH key auth works
The six-step handshake — key offer, challenge, signature, verification, channel open. Watch an animated client/server diagram light up each arrow.
TLS handshake, deep
Open every TLS 1.3 message — ClientHello, ServerHello, Certificate, CertificateVerify, Finished. Cipher suites, HKDF key derivation, SNI, ALPN, and why TLS 1.3 has built-in perfect forward secrecy.
systems · 10 lessons
Ansible control node & inventory
Ansible is agentless — one control node pushes work to a fleet over SSH. Install ansible-core, write an inventory with groups, ping the fleet, and fire ad-hoc commands. RHCE-ready.
Ansible playbooks & YAML
Plays, tasks, and idempotency. Watch a playbook run task-by-task — ok, changed, skipped — then run it again and watch everything go green with 0 changed. RHCE-ready.
Ansible core modules
file, user, copy, dnf, service — the modules that do the real work. Declare the desired state and let Ansible converge to it, idempotently. RHCE-ready.
Ansible variables & facts
Which value wins when the same variable is set in five places? Variable precedence, gathered facts, and ansible_facts — visualized as a ladder. RHCE-ready.
Ansible loops & conditionals
Run one task many times with loop, and skip it cleanly with when. Plus changed_when / failed_when to control what 'changed' and 'failed' even mean. RHCE-ready.
Ansible templates (Jinja2)
One .j2 template, a different rendered config on every host. Jinja2 variables, loops, and filters turning facts into real config files. RHCE-ready.
Ansible handlers & notifications
Restart the service only when the config actually changed. Watch notify queue a handler and flush it exactly once at the end of the play. RHCE-ready.
Ansible roles
Stop copy-pasting playbooks. The role directory layout, how tasks/handlers/templates/defaults fit together, and pulling roles from Galaxy. RHCE-ready.
Ansible Vault
Keep passwords out of plaintext YAML. Encrypt, edit, view, and rekey secrets, then feed the vault password into a playbook run. RHCE-ready.
Ansible error handling
block / rescue / always, ignore_errors, and failed_when — try/catch for playbooks. Watch a failing task trigger its rescue and run cleanup. RHCE-ready.
Cards marked SOON are designed and on the roadmap — they don't exist yet. New lessons drop as their animations are ready.