tcpdump:tldr:3594a

The command "tcpdump -r ${dumpfile-pcap}" is used to read and analyze the data captured in a packet capture file (in pcap format), which is specified by the variable ${dumpfile-pcap}.

Here is a breakdown of the command:

• "tcpdump" is a command-line network traffic analysis tool that allows you to capture and display network packets.
• The "-r" option is used to specify that the input should be read from a file, rather than from a live network interface.
• "${dumpfile-pcap}" is a variable placeholder for the actual name of the pcap file you want to analyze. The variable name itself depends on the context in which the command is being used.
• Together, "-r ${dumpfile-pcap}" instructs tcpdump to read the specified pcap file and analyze its contents.

By running this command, tcpdump will open the pcap file and display the captured network packets based on the given filters and options, providing insights and information about the network traffic contained within the file.