Linux packet capture analysis (tcpdump) and linux packet capture tcpdump

Linux packet capture analysis (tcpdump) and linux packet capture tcpdump
Start by default

Tcpdump

Under normal circumstances, directly starting tcpdump will monitor all the data packets flowing through the first network interface.

Monitors data packets of a specified network interface

Tcpdump-I eth1

If no Nic is specified, the default tcpdump only monitors the first network interface, which is usually eth0. In the following example, no network interface is specified.

View local network interfaces

Ifconfig

Find the network interface of your ip address

Monitors data packets of specified network interfaces and ports

Tcpdump-I eth0 tcp port 8809

Linux tcpdump packet capture Analysis

Tcpdump packet capture is triggered as long as a tcp connection exists. For packet analysis, we need to understand the tcp packets.

Packet capture with tcpdump in linux

Add the-nn parameter: Do not convert the address and port to the name
Tcpdump-I eth0-nn host 61.139.142.26-c 1000-w/root/a. cap