A sniffer, also known as a packet analyzer, is a software tool used to monitor and analyze network traffic. These tools can intercept, record, and analyze data packets transmitted between devices on a network, allowing system administrators and security researchers to examine the content and structure of these packets.
An Ethernet sniffer generally operates in promiscuous mode, allowing the network card to capture all packets passing through the network, regardless of whether they are destined for the device running the sniffer. A Wi-Fi sniffer, on the other hand, requires the wireless network card to operate in monitor mode, enabling packet capture without associating with a specific Wi-Fi network.
Wireshark is a popular open-source packet analysis tool that can be used as a sniffer on Ethernet networks.