Networking & Firewall (Ss/Netstat/Iptables/Nftables/Curl)

Stop wondering if your local service is actually listening on all interfaces

🧩 The Challenge

Spent three hours tearing my hair out trying to connect to a new database instance, only to realize I bound it to 127.0.0.1 instead of the actual network IP. We’ve all been there, and it’s usually the simplest mistake that ruins your Friday afternoon.

💡 The Fix

Use the ss command with a specific filter to see exactly which sockets are bound to your public interface. It’s way faster than guessing if your firewall is blocking traffic or if the app is just hiding from the network.

ss -tlpn 'src = 192.168.1.50'

⚙️ Why It Works

Adding the src filter forces the kernel to return only the sockets listening on that specific interface, saving you from parsing a massive list of local loopback connections.

🚀 Pro-Tip: Alias this to something like ‘nosh’ so you don’t have to remember the flags when you’re under pressure.

Linux Tips & Tricks | © ngelinux.com | 7/18/2026