The SUSE operating system must not send Internet Protocol version 4 (IPv4) Internet Control Message Protocol (ICMP) redirects.

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.

Verify the SUSE operating system does not send IPv4 ICMP redirect messages.

Check the value of the "all send_redirects" variables with the following command:

# sysctl net.ipv4.conf.all.send_redirects net.ipv4.conf.all.send_redirects =0

If the returned line does not have a value of "0” this is a finding.

Configure the SUSE operating system to not allow interfaces to perform IPv4 ICMP redirects.

Set the system to the required kernel parameter by adding the following line to "/etc/sysctl.conf" (or modify the line to have the required value):

net.ipv4.conf.all.send_redirects=0

Run the following command to apply this value:

# sysctl --system