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

Stop wondering why your TCP connections are stuck in limbo

🧩 The Challenge

Ever been troubleshooting a web app where the server stops responding, but netstat looks totally fine and you feel like you’re losing your mind? I spent half a Friday once chasing ghosts because I didn’t realize the socket buffer was actually backed up.

💡 The Fix

Use ss to peek directly at the send and receive queues of your sockets, which shows you exactly which connections are actually choking on data. It’s way more informative than the old tools.

ss -ntuA 'all' state established '( dport = :80 or dport = :443 )'

⚙️ Why It Works

This command forces the socket statistics to ignore the noise and focus on the buffers, letting you see if the Send-Q or Recv-Q numbers are stuck above zero. High values there are the smoking gun for an application that’s too slow to keep up with the network.

🚀 Pro-Tip: Always keep an eye on the Recv-Q; if it’s consistently non-zero, your app is definitely dropping the ball.

Linux Tips & Tricks | © ngelinux.com | 8/22/2026