IT professional writing about cybersecurity, cloud & DevOps, automation, networking, and systems administration. Real-world guides for real-world problems.
Networking from Scratch (lesson 17) — why 2.4 GHz only has three usable channels, the practical 5 GHz channel plan, what 6 GHz changes, the AP-placement and power decisions that beat any equipment upgrade, the 802.11k/v/r fast-roaming trio, band steering, minimum data rates, and the RSSI/SNR/utilisation thresholds that turn Wi-Fi performance complaints into numbers.
Networking from Scratch (lesson 16) — how the 4-byte 802.1Q tag splits one switch into many logical networks, what access and trunk ports actually do, why the native VLAN bites people, voice-VLAN multiplexing, why DTP is usually disabled, and the verification commands that make switch CLI output debuggable.
Networking from Scratch (lesson 15) — the three flavours of NAT (static, dynamic, PAT), how port translation actually multiplexes one public IP across hundreds of inside hosts, the conntrack table that makes it work, why STUN/TURN/ICE exist, what CGNAT does to your mobile traffic, and why IPv6 throws the whole machinery away.
Networking from Scratch (lesson 14) — how a 128-bit IPv6 address is built and compressed, why every interface has three of them at once, how SLAAC lets a host self-configure with no DHCP, what replaces ARP and broadcast, the privacy extensions that change your address daily, and the dual-stack reality that’s still the norm 25 years in.
Networking from Scratch (lesson 13) — twenty-five subnetting practice problems across five difficulty tiers (classful warm-up, /25-/30 in the 4th octet, octet-boundary, VLSM carving, real-world planning) with step-by-step solutions for every one. Designed to take you from "I read the math" to "subnetting is reflexive" in one sitting.
Networking from Scratch (lesson 12, the capstone) — the six stages of a typical intrusion (initial access, foothold, lateral movement, privilege escalation, C2 + persistence, exfil + impact), the protocols attackers actually use, and the highest-leverage defence at each stage. Closes out the foundation pathway.
Networking from Scratch (lesson 11) — what a VPC actually is, why every cloud subnet is bound to one AZ, what really makes a subnet public or private, the four gateways (Internet, NAT, Peering, Transit), security groups vs NACLs, connecting to on-prem with VPN or dedicated interconnects, and the pets-vs-cattle mindset shift that changes how you think about IPs.
Networking from Scratch (lesson 10) — the middleboxes a packet traverses on the way to a real-world server (firewalls, load balancers, proxies, IDS/IPS, WAFs, VPN gateways), what each one does and where it sits, plus the internet hierarchy from IANA through RIRs and ISP tiers to IXPs and CDNs.
