tshark: Wireshark in the Terminal
Wireshark’s full dissector library driven from an SSH session: capture filters against display filters, custom field output, ring buffers and the statistics taps that make triage fast.
Labs
Hands-on Cisco IOS XE lab walkthroughs. Each lab ships with a real CML topology, configs you can paste, and verified show output. Articles tagged Labs cover the full CCNA 200-301 blueprint across Network Fundamentals, Network Access, IP Connectivity, IP Services, and Security Fundamentals.
Latest posts — page 3
SSH Beyond Login: Tunnels, Jump Hosts, scp/sftp
Local, remote and dynamic forwards, ProxyJump instead of agent forwarding, scp -O against IOS XE, and why telnet is still a fine port tester.
socat: Port Forwarding and Bidirectional Relays
One command joins any two endpoints: TCP, UDP, TLS, UNIX sockets, serial ports or a program. Port forwards, TLS wrappers and protocol bridges from real captures.
netcat: Port Checks, File Transfers, Listeners
Open, refused, timed out and no route to host are four different tickets. Plus banner grabs, file transfer with no server, and why UDP tests lie.
wget: Downloads, Mirrors, Connectivity Tests
The retry and resume behavior that makes wget worth keeping, spider mode as a health check, rate limiting, and the robots.txt rule that empties your mirror.
curl for Network Engineers: Ports, HTTP, APIs
Prove a port is open, split DNS from TCP from server think time, test a device API and read a TLS failure, all with real output from a routed lab.
How Linux Resolves Names: resolv.conf, systemd-resolved, nsswitch
dig tests a nameserver. getent tests name resolution. The full path from nsswitch.conf to the wire, with the resolver deliberately broken and fixed.
dig: The Complete DNS Query Guide
Read the status line first. Flags, sections, TTLs, delegation traces and DNSSEC, all against a real authoritative server in the lab.
netstat vs ss: Why It Was Replaced and How to Switch
The full command map, wall clock timings on a host holding ten thousand sockets, and the surprise result when you add process lookup.
ss: The Modern Socket Statistics Tool
Queue columns that tell you which end stopped working, filters that run in the kernel, and the TCP internals nothing else on the box will give you.
tracepath and Path MTU Discovery on Linux
Small things work and big things hang. One unprivileged command finds the narrow link, and one iptables rule shows what a black hole looks like.
mtr: Continuous Path Monitoring on Linux
Loss and latency per hop against a link with 12 percent loss injected on purpose, and the one rule that separates real loss from cosmetic loss.