A service times out. The logs say nothing. Is it the app, DNS, a firewall rule, or something worse? 🐧

Before reaching for heavy tooling, a few built-in commands answer most of it:

  • ip -br addr and ip route: what does this host think its network looks like? 🔍
  • sudo ss -tulpn: what is listening, and which process owns it? 🔗
  • dig example.com +short: does DNS agree across resolvers? 🌐
  • curl -I https://example.com: what do the headers and redirects reveal?
  • nmap -sV against your own hosts: what is exposed? (authorized systems only) 🛡️

I put together a full cheat sheet covering 13 commands (ip, ifconfig, ping, traceroute, netstat, ss, wget, curl, scp, rsync, dig, nslookup, nmap) with a five-minute Linux incident response workflow, safety warnings, and indicators worth escalating.

Read it here: https://www.xpert4cyber.com/2026/10/linux-networking-commands-cheat-sheet.html

What is your go-to command when the network looks wrong?