From the course: Cisco Certified Network Associate (CCNA) v1.1 (200-301) Cert Prep

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Port security theory

Port security theory

From the course: Cisco Certified Network Associate (CCNA) v1.1 (200-301) Cert Prep

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Port security theory

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(bright music) - [Instructor] At this point in the lesson, we've seen a couple of ways of launching a man-in-the-middle or an on-path attack. And in this video, we'll take a look at yet another way and a Cisco switch security feature that can help us out. Consider this scenario. Let's say that we have an attacker that gets access to a switch port and they send a series of frames into that switch. And here's the interesting thing, each of those frames claim to come from a different source MAC address. And if they continually bombard that switch port with frame after frame each claiming to be from a different MAC address, then that switch's MAC address table can fill to capacity. What happens if a MAC address table fills to capacity? Well, if a new device plugs in or boots up on that switch, their MAC address will not be learned by the switch. It's almost as if they're connected to an old ethernet hub, meaning that that attacker can connect to the switch and capture traffic and see…

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