Tcpdump

Tcpdump is a long-standing open-source tool for capturing and examining network packets from the command line. Its strength is simplicity and direct access to traffic: engineers and analysts can select interfaces, apply Berkeley Packet Filter expressions and save captures for deeper investigation. Security teams often use packet captures when they need evidence that is not available from application logs or endpoint telemetry, while developers and network administrators rely on Tcpdump to troubleshoot protocols and connectivity. The tool is lightweight enough for use on servers and network systems where a full graphical monitoring platform would be unnecessary. Because Tcpdump produces standard packet-capture data and works with libpcap, it also fits naturally into broader network-analysis workflows.