Performance Tuning & Kernel Parameters (Sysctl)
Stop your server from forgetting connections under heavy load
🧩 The Challenge
Dealing with a web server that suddenly stops responding while the CPU is barely idling? You’ve likely hit the ephemeral port limit, and it feels like the kernel is just ghosting your traffic.
đź’ˇ The Fix
Increase your local port range to give the networking stack enough breathing room to cycle through connections. It stops the “cannot assign requested address” errors that haunt high-traffic services.
sysctl -w net.ipv4.ip_local_port_range="1024 65535"⚙️ Why It Works
By default, many distros cap your range at around 32k ports, which is honestly pathetic for a modern high-concurrency app. Expanding this lets the OS track way more concurrent sockets simultaneously.
🚀 Pro-Tip: Verify the change sticks after a reboot by adding it to /etc/sysctl.conf instead of just setting it live.
Linux Tips & Tricks | © ngelinux.com | 9/16/2026