Tcpdump

tcpdump is a common packet analyzer that runs under the command line. It allows the user to capture and display network traffic including TCP/IP packets.

Basic examples

• tcpdump -i en0
• tcpdump -n -i en0
• tcpdump 'port 80 or 443'
• tcpdump dst 8.8.8.8

See also

• Packet analyzer: tcpdump, Wireshark, snoop (Solaris), ngrep, Wireshark, dSniff, netsniff-ng, Corvil, PAN-OS, pcap

https://danielmiessler.com/study/tcpdump/