Internet Control Message Protocol (ICMP) flood attack is also known as Ping flood attack. It is a common Denial-of-Service (DoS) attack. In an ICMP flood attack filtering, hackers target a particular device with ICMP echo-requests (pings). ICMP echo-request and echo-reply messages are particularly used to ping a network device to find the health and connectivity of the device. It shows the connection between the sender and the device. It will make the target inaccessible to normal traffic. The attacker needs to know the IP address of the target. The protection level is based on the traffic pocket’s number, and the protection will be activated when the number of packets crosses the preset threshold value. You can set the value from the Advanced section. Select System Tools and go to System Parameters. Select DOS Protection Level Settings to see the host list. Consider the procedure that is given below to activate ICMP flood attack filter.