Information
ICMP redirect messages are used by routers to inform hosts that a more direct route exists for a particular destination. These messages contain information from the system's route table, possibly revealing portions of the network topology.
Solution
Configure the system to not allow interfaces to perform IPv4 ICMP redirects by default.
Set the system to the required kernel parameter by adding the following line to '/etc/sysctl.conf' or a configuration file in the /etc/sysctl.d/ directory (or modify the line to have the required value):
net.ipv4.conf.default.send_redirects = 0
Issue the following command to make the changes take effect:
# sysctl --system