https://f0o.dev/tags/tcp/ Recent content in Tcp on Daniel 'f0o' Preussker Hugo -- gohugo.io en-us Sat, 18 Apr 2026 00:00:00 +0000 https://f0o.dev/research/2026/04/exploiting-tcp-handshake-quirks-for-ip-verification/ Sat, 18 Apr 2026 00:00:00 +0000 https://f0o.dev/research/2026/04/exploiting-tcp-handshake-quirks-for-ip-verification/ <p>It&rsquo;s an incredibly frustrating reality that we&rsquo;re still battling TCP SYN Floods with spoofed IPs in 2026.</p> <p>ISPs completely ignoring BCP38 is a rant for another day. Right now, I want to talk about how we can actually solve the problem using a beautiful quirk in the TCP stack.</p> <p>The core concept relies entirely on how operating systems handle unexpected ACK numbers, and how we can weaponize that behavior for defensive purposes.</p>