Network
tcpdump
Capture and analyze network traffic on an interface.
Synopsis
syntax
tcpdump [OPTION]... [EXPRESSION]
Examples
Capture all traffic on eth0
sudo tcpdump -i eth0
Capture HTTP traffic
sudo tcpdump -i any port 80 -n
Save 100 packets to file
sudo tcpdump -i eth0 -c 100 -w capture.pcap
Read pcap and show ASCII payload
tcpdump -r capture.pcap -A
Common options
| Flag | Description |
|---|---|
| -i | Interface to capture on |
| -n | Don't resolve hostnames |
| -c | Capture N packets then stop |
| -w | Write to pcap file |
| -r | Read from pcap file |
| -v | Verbose output |
| -A | Print packet payload in ASCII |
About tcpdump
The `tcpdump` command capture and analyze network traffic on an interface. Networking commands handle connectivity testing, DNS resolution, data transfer, remote access, firewall rules, and traffic analysis.
Linux is the dominant server operating system, and strong networking skills are essential for web hosting, container orchestration, security auditing, and infrastructure management. The command accepts 7 commonly used flags shown above, though the full set of options is available in the man page (`man tcpdump`).
The 4 examples on this page cover typical real-world usage patterns that you can copy and adapt for your own workflows.
Related commands
More Network Commands
Other commands in the Network category