Introduction: Running Out of Air
Imagine you have a private bus that only has 10 seats. A hacker hires 10 people to sit on the bus and never get off. Even though they aren't 'attacking' the bus, they are using up all the room, so your real customers can't get a seat. In networking, this is an IP Exhaustion Attack. It’s a method where a hacker opens so many 'half-finished' connections that your server runs out of IP space or memory to handle any new ones.
In this guide, we'll explain how this attack works and how to shield your cloud API from it.
How It Works: The SYN Flood
The most common version of this is called a **SYN Flood**. A hacker sends the first part of the 'Handshake' (the SYN packet) to your server thousands of times a second. Your server 'reserves' a tiny bit of its IP resources and waits for the user to finish the handshake. But the hacker never finishes. Soon, your server is 'full' of waiting, half-finished connections, and the real users get a 'Server Unavailable' error.
The Defensive Shield
- SYN Cookies: This is a brilliant mathematical trick. Your server doesn't 'reserve' any room until the handshake is 100% finished. It uses math to remember the request without needing to save any data. This makes your server effectively immune to basic SYN floods.
- Connection Timeouts: Set your server to 'kill' any connection that doesn't finish its handshake within a few seconds. This prevents 'Hanging' connections from using up your resources.
- IP Filtering (WAF): Use a Web Application Firewall like Cloudflare or AWS WAF. These services are massive and can 'soak up' millions of fake connections before they even touch your sensitive internal data center.
Conclusion
IP Exhaustion is about 'Resource Wars'. By using smart protocol tricks and a strong external firewall, you can ensure that the 'seats' on your bus are always available for your real customers. See your current connection health here.