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Hi. What’s your topology? Generally the Service Providers sell public IP addresses through a fiber optic interface and they give you a terminal (Optical Network Terminal), that technically speaking includes a router, a switch, a firewall and wireless interfaces, all in the same box.

An example of a home topology is:

(Internet)—> ISP—>ONT (“Router”)—>Switch—>PC

If your switch is on a different box, all the interfaces will have Internet access with the public IP.

I’m understanding your computer is plugged in one of that switch interfaces, right? Is that fe:dc:05:41:38:8k?

Remember the number of MAC addresses a switch has depends on the number of physical network interfaces, so if your switch has 4 Ethernet and 1 wireless card, it will have 5 MAC addresses in total.

Now, the answer of your question depends on the network topology, what else is plugged in your switch, another switch(es)? A lot of wireless devices? Do you recognize the IPs T2 is being asked for by fe:dc:05:41:38:8k? Are they private addresses in a segment/VLAN you recognize?

In any way, the solution is to filter by MAC and only allow known MACs access the switch. This can be configured in the router or switch, if it’s an administrable one.