Nmap -sV turns port 80 open into nginx 1.29.8. This guide covers what version detection actually sends, how to read the fingerprint results, and how to tune intensity when it guesses wrong.
ACK, FIN, NULL, Xmas, Window, and Maimon: what each Nmap TCP scan type detects, which flags it sets, and where each one lies to you when the target stack does not play by the rules.
How the SYN scan works, how it differs from a connect scan, how to choose which ports to hit, and the lesson that matters most: reading open, closed, and filtered correctly instead of guessing.
How Nmap decides a host is up: ping sweeps, ARP on local networks, and when to reach for -Pn. Learn why discovery differs for local and remote targets and how to read the results like an engineer auditing your own gear.
PortFast skips the 30-second spanning tree wait so a host gets an IP the moment it plugs in. This post covers where it belongs, where it can take down a network, and the two guard features that keep it safe.
The native VLAN is the one untagged VLAN on an 802.1Q trunk, and it can break a link through a mismatch or get hopped through double tagging. This post explains why it exists, both failure modes, and how to configure it safely.
CML 2.10 shows the Docker node definitions but no image definitions. Here is how to install the container images (net-tools, nginx, Snort, TACACS+, Splunk and more) from Cockpit.
Still worth it for most people, with one big caveat. The honest take on the 2026 to 2027 exam change, what the cert actually gets you, and the AI question.
Before LSA types make sense, you need what an LSA actually is: one record in the link-state database describing one piece of the network. This post covers the LSA as a building block and how it gets everywhere it needs to be.
Basic BGP peering takes half a dozen lines; what trips people up is eBGP vs iBGP behavior, getting routes into BGP, and the iBGP next-hop quirk that silently breaks reachability. A full IOS XE walkthrough.
Every Cisco AP mode explained: Local, FlexConnect, Monitor, Sniffer, Rogue Detector, SE-Connect, Bridge and Mesh. What each does and when to use it.