ICMP protocol and related kernel parameters

ICMP (INTERNET CONTROL MESSAGE PROTOCOL) Network Control message Protocol. Belongs to the TCP/IP protocol family, works in the network layer (layer 3), and is used to transmit control messages between IP hosts and routers. The control message refers to the message of the network itself, such as whether the network is unreachable, whether the host is reachable, whether the route is available, and so on. Although these control messages do not transmit user data, they play an important role in the transmission of user data.

For query messages, commonly used ping commands, and for diskless systems to start to obtain network subnet mask query messages and timestamp messages, the target host receives a response packet that returns the corresponding format; for error messages, the target host will not return the corresponding data packet in some cases:

Next, list the ICMP-related kernel parameters in the Linux system:

The parameters can be modified in / etc/sysctl.conf, viewed using sysctl-a, and modified using sysctl-w parameter=VALUE.