Which tool is used to capture network packets and store the sniffed data into a file?

The tool used to capture network packets and store the sniffed data into a file is tcpdump. This command-line utility allows users to intercept and log traffic that passes over a network to which the computer is attached. Tcpdump is widely used for network analysis and troubleshooting, as it provides the ability to capture both individual packets and entire sessions of traffic.

When using tcpdump, you can specify various filters, such as particular protocols, ports, or IP addresses, to narrow down the captured data to what's relevant for analysis. The output can be saved directly to a file, making it easy for users to analyze the data later with other tools or perform forensic analysis.

While Wireshark is also a popular tool for packet analysis, it is primarily a graphical interface for analyzing previously captured packets, not specifically designed to directly capture packets by itself without external tools like tcpdump or similar. The mention of "sniffer" is a general term that refers to any tool that captures network packets, without specifying a particular implementation, and is not a standalone tool. Similarly, "netcap" is not a recognized standard tool in the context of packet capturing and analysis. Therefore, tcpdump stands out as the appropriate choice for this question.