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

Stop the invisible firewall from killing your health checks

🧩 The Challenge

Dealing with a load balancer that suddenly marks your backend as down is infuriating when you know the service is listening perfectly fine. I spent three hours last week realizing the nftables ruleset had a subtle shadowing issue that was silently dropping packets from the monitoring range.

💡 The Fix

Dump your exact runtime ruleset to a file so you can actually read the logic instead of guessing what might be applied in the kernel. You’ll see exactly which table or chain is acting like a gatekeeper.

nft list ruleset > current_rules.txt

⚙️ Why It Works

Since the kernel doesn’t keep your original config comments or formatting, dumping the live state gives you the raw truth of what traffic is hitting the floor. It cuts through the mess if you’ve been editing rules on the fly and lost track of the current order.

🚀 Pro-Tip: Use the -a flag if you want to see the handle numbers for easier rule deletion later.

Linux Tips & Tricks | © ngelinux.com | 9/7/2026