IT professional writing about cybersecurity, cloud & DevOps, automation, networking, and systems administration. Real-world guides for real-world problems.
Networking from Scratch (lesson 4) — the DHCP DORA four-packet exchange, lease and renewal mechanics, common DHCP options, the cross-subnet relay agent, and the ARP request/reply that turns an IP into the MAC the wire actually delivers to. Plus the symptoms of common failure modes.
Networking from Scratch (lesson 3) — the four-line magic-number method for finding the network ID, broadcast, usable range, and next subnet for any /N. Three worked examples (including the awkward one across an octet boundary), a size cheat sheet, and five practice problems with answers.
Networking from Scratch (lesson 2) — what an IPv4 address actually is, why it has four numbers, what a subnet mask does, what CIDR notation means, and how a computer uses it to decide whether to deliver locally or send to the gateway. Plus the special address ranges every admin should recognise on sight.
Networking from Scratch (lesson 1) — an end-to-end walkthrough of the eight things that happen between clicking a link and seeing the page on your screen. DNS, ARP, routing, TCP, TLS, HTTP, render, and where to look when each one breaks. No prior experience required.
A field guide to investigating Business Email Compromise (BEC) intrusions in Office 365 — 10 steps covering scope, log collection, forwarding rules, login analysis, permission changes, OAuth2 abuse, evasion, data-access assessment, threat intelligence, and recommendations.
Three concrete AD delegation scenarios with the right ACL technique for each: targeted Deny ACEs to hide mobile and pager from a Hardware Support team, the schema confidential bit to restrict national-ID attributes to HR, and a volume-object ACL to make a published share invisible to everyone except Finance.
Use ntdsutil to create IFM media on an existing healthy Domain Controller, copy it to a target server at a remote site, and promote that server with the Install from media option to skip full WAN replication.
Use Windows Admin Center to toggle Remote Desktop on a Windows Server without first having to RDP in — enable RDP with NLA, then verify with the classic mstsc client and with WAC built-in in-browser Remote Desktop tool.
