Tcpdump

Summary

tcpdump is a command-line packet analyzer (or packet sniffer) that allows users to capture and inspect network traffic in real time. It is commonly used for network troubleshooting, debugging, and security analysis. tcpdump works by intercepting and displaying the packets being transmitted or received over a network interface, giving users detailed information about network activity.

General

Common Tasks

-n

Don't resolve IP addresses.

-i {interface}

Specify an interface to capture on.

-w {file}

Save output to file.

-vv

Show verbose output on screen.

(this is helpful to keep track of how many packets you've captured)

Ctrl+C

Stop the capture.

Capture all traffic on an interface

sudo tcpdump -ni ens192 -w capture.pcap

Capture all traffic involving a specific host

sudo tcpdump -ni ens192 host 10.0.0.1 -w capture.pcap