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

Stop mystery firewalls from dropping your packets in silence

🧩 The Challenge

Dealing with a service that simply refuses to respond to requests is a nightmare when you have no idea if the packet even made it to the application. You check the process, check the config, and pull your hair out while the connection just times out.

💡 The Fix

Use the TRACE feature in nftables to log exactly which rule is dropping your traffic in real time. It saves you from guessing which chain is swallowing your packets.

nft add rule ip filter input tcp dport 80 log prefix "DROP-TEST: " drop
nft monitor trace

⚙️ Why It Works

Adding a trace rule forces the kernel to send netlink events for every packet matching your criteria, showing you the exact rule index that caused the rejection. It basically gives you a play-by-play of your packet’s life and death inside the firewall.

🚀 Pro-Tip: Don’t leave these trace rules active on a high-traffic production server or you’ll crush your system logs in seconds.

Linux Tips & Tricks | © ngelinux.com | 10/19/2026