{"id":85562,"date":"2026-07-06T06:54:20","date_gmt":"2026-07-06T06:54:20","guid":{"rendered":"https:\/\/www.eccouncil.org\/cybersecurity-exchange\/?p=85562"},"modified":"2026-07-06T07:00:26","modified_gmt":"2026-07-06T07:00:26","slug":"arp-poisoning","status":"publish","type":"post","link":"https:\/\/www.eccouncil.org\/cybersecurity-exchange\/ethical-hacking\/arp-poisoning\/","title":{"rendered":"ARP Poisoning"},"content":{"rendered":"\t\t
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Let’s talk about how networks really work. We build them on trust. For a laptop to talk to a server, your phone to connect to a Wi-Fi, or a smart device to ping the cloud, they all rely on a simple, decades-old protocol called ARP, or Address Resolution Protocol. ARP\u2019s job is straightforward: it translates IP addresses into physical MAC addresses, so data packets know exactly where to go (Plummer, 1982).<\/p>

The problem? ARP was born in a friendlier time. It assumes everyone on the network is telling the truth. There\u2019s no verification. This blind trust is its Achilles’ heel, and attackers exploit it through a trick called ARP poisoning (also called ARP spoofing). By lying in ARP responses, they convince your device that their computer is the network gateway or another trusted machine. Suddenly, your traffic flows through them. They can eavesdrop, alter data, or just shut things down.<\/p>

This isn’t a textbook threat. It\u2019s a real-world weapon used for everything from snooping on campus networks to corporate espionage. It\u2019s the first step in more complex attacks, setting up a perfect man-in-the-middle (MITM) position to steal logins or deliver malware. On a poorly secured network, an attacker can own the traffic in minutes.<\/p>

Let’s break it down. We’ll look at how ARP works, how the attacks play out, the real damage they’ve caused, and, most importantly, how to build your defenses.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t

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The Nuts and Bolts of ARP<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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Think of your local network like a neighborhood. IP addresses are the street addresses, but Media Access Control (MAC) addresses are the specific lock on your front door. ARP is the process of looking up a street address to find out which lock it uses.<\/p>

Here\u2019s how a normal conversation goes:<\/p>

  1. Your computer (Device A) shouts to the entire network, “Hey, who has IP address 192.168.1.100? Send your MAC address to me!”<\/li>
  2. The correct device (Device B) hears the shout and replies directly, “That’s me. My MAC address is AA:BB:CC:DD:EE:FF.”<\/li>
  3. Your computer makes a note of this pairing in its short-term memory (the ARP cache) and starts sending data.<\/li><\/ol>

    The weakness is right there in step two. Your computer will believe any answer it gets, no questions asked. It\u2019s like accepting directions from anyone who shouts back, without checking a map.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t

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    What Exactly Is ARP Poisoning? <\/h2>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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    ARP poisoning is the network equivalent of cutting into a phone line. An attacker on the same local network sends out a forged message that says, “Hey, I’m the router! My MAC address is [Attacker’s MAC].” Your computer, trusting as ever, updates its ARP cache with this bogus information. Now, all your internet traffic gets sent to the attacker’s machine first. They can then:<\/p>