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

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-77499	SLES-12-030420	SV-92195r3_rule		Medium

Description
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.

STIG	Date
SLES 12 Security Technical Implementation Guide	2018-09-27

Details

Check Text ( C-77059r1_chk )
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.default.send_redirects net.ipv4.conf.default.send_redirects = 0 If the returned line does not have a value of "0” this is a finding.

Fix Text (F-84141r3_fix)
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