SD-WAN has two routing problems at once: how sites learn prefixes across the overlay with OMP, and how the physical transports route underneath. This post keeps the two layers separate using the Cisco Catalyst SD-WAN model.
A wireless LAN controller turns a pile of access points into a managed network: the APs become radios and the WLC becomes the brain. Covers the problem it solves, the controller-and-AP split, and WLC form factors.
Nmap's -oN, -oX, -oG, and -oA output formats, when each one earns its place, and the shell one-liners that turn a saved scan into an answer. Save scans you can diff week over week and hand to the audit team as evidence.
Nmap's timing templates -T0 through -T5 and its rate control flags decide whether a scan finishes fast or slips under an IDS. This guide shows when to push packets on a /16 sweep and when to trickle probes past a rate-based SIEM alert.
Nmap's evasion flags are your test harness: fragmentation, decoys, source-port tricks, and timing, run against your own firewall and IDS to prove your controls actually catch them. Real captures from a Cisco lab and the internet.
NSE turns Nmap from a port scanner into an inventory and audit tool: enumerate HTTP methods, list SSH algorithms, flag open directory listings. This post covers the script categories with real captured output.
Half your infrastructure runs on UDP: DNS, SNMP, NTP, DHCP. This guide covers how nmap -sU decides port states, how to read the ambiguous open|filtered results, which UDP services are worth scanning, and how to keep a scan from taking all night.
Nmap -O fingerprints a host's TCP/IP stack to guess its operating system, no login and no banner required. Learn what it measures, how to read every field it prints, and why it fails in predictable ways on lab gear and appliances.
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.