1. Host: Host, desktop, notebook, mobile phone and other equipment
2. Network medium: network cable, optical fiber, wireless network Wi-Fi. mobile network
3. Data: a string of subsections
Detection of network communication : install wireshark, usually called a packet capture tool
catch, capture
packet, packet, packet
Filter rules : 1. Filter IP
p.addr eq 192.168.1.107 // Both source IP and destination IP can be displayed
2. Filter ports
tcp.port eq 80 // display whether the port is source or destination
IP address : used to identify a host on the network with 4 bytes
When expressed as a string, decimal, separated by dots, 0～255
ping , to detect Unicom, the terminal command format is: ping IP address
Request timeout : 1. The other party shuts down and is offline
2. You are not connected to the Internet
3. The other party is online, but the ping service is blocked
Check your own IP address :
windows：ipconfig
linux/macos：ifconfig