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PJ Pérez

Why Modern Tunnels Fail: The Silent War Against Detection

When engineers think about censorship and detection, they often imagine simple keyword filters, deep packet inspection, or IP blocks. They miss the real threat. Modern detection is statistical, adaptive, and fast. It does not care about encryption. It does not need to know what you are sending. It only needs

NAT as a Security Measure: Safeguarding Home Office Users for Two Decades

Since the widespread adoption of DSL (Digital Subscriber Line) internet in the early 2000s, Network Address Translation (NAT) has played a pivotal role in securing home office networks. NAT, often implemented in consumer-grade routers, has become an unsung hero in protecting home users from a wide range of cyber threats.

Windows Firewall traffic audit

Windows Firewall is a Windows built-in security feature that helps protect your system by filtering incoming and outgoing traffic based on predefined rules. While the firewall does a great job of blocking unwanted traffic, there are times when you need to dig deeper. For instance, you might want to: * Verify

Firewall bypass: Encapsulating traffic inside UDP

On our last post about UDP hole-punching we learned how we could use UDP traffic to exploit the stateful nature of firewalls, thus bypassing blocks for incoming connections. That was a fun exercise, but of limited use in the real world. On this post we’re going to turn it

Firewall and NAT bypass: UDP hole punching

This post was originally published in 2018 Intro UDP hole punching is a widely documented firewall bypass technique. It doesn’t exploit any bugs or flaws, it does exploit UDP’s sessionless nature and firewalls’ stateful nature. The technique relies on the fact that in a UDP conversation there is