MAC Spoofing and ARP Poisoning: The Local Man-in-the-Middle

Introduction: The Fake Gateway

Imagine sitting in a coffee shop. Your computer wants to talk to the Router (Gateway). To do this on the local network, your computer uses ARP (Address Resolution Protocol) to ask "Who has the IP address 192.168.1.1?". ARP Poisoning is what happens when a hacker yells back, "I do!"

The Interception

By constantly sending out fake ARP replies, the hacker tricks your computer into believing that their laptop is the real router. Now, all your traffic goes through them before going to the internet. They are now the 'Man-in-the-Middle', capable of reading unencrypted passwords and sniffing sensitive data.

Conclusion

ARP Poisoning relies on the fact that local networks are built on 'Blind Trust'. It’s why you should treat public Wi-Fi as a hostile environment. Test your local ARP table here.