In the “DDOS attack solution part 3” we have installed the csf firewall to stop the DDOS but still receiving the heavy DDOS attack in that case, simply open the /etc/sysctl.conf file and make the following changes.
net.ipv4.tcp_syncookies = 1
net.ipv4.tcp_fin_timeout = 30
net.ipv4.tcp_window_scaling = 0
net.ipv4.tcp_sack = 0
To update the changes run the command, so that new values will be updated.
For further DDOS attack solution check the “DDOS attack solution part 5”