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When I open wireshark I could see the packets send by machines other than mine. How could its possible?

Example

8252    99.150192   somoeneip   239.255.255.250 SSDP    NOTIFY * HTTP/1.1 
8253    99.151204   fe8s0::15s34:12c8:2f2132:d99221 ff02::c SSDP    NOTIFY * HTTP/1.1 
8075    96.624367   otherip 239.255.255.250 SSDP    NOTIFY * HTTP/1.1 

Values are modified for privacy

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1 Answer 1

up vote 6 down vote accepted

Take a peek at those IP addresses. They're within one of the reserved IP address blocks: the multicast block.

multicast is the delivery of a message or information to a group of destination computers simultaneously in a single transmission from the source

The reason you're seeing those packets from other machines is because they're being sent to anyone listening.

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