The system must not send IPv4 ICMP redirects by default.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-59749	AOSX-10-001210	SV-74179r1_rule		Medium

Description
ICMP redirects are broadcast in order to reshape network traffic. A malicious user could use the system to send fake redirect packets and try to force all network traffic to pass through a network sniffer. Disabling ICMP redirect broadcasts mitigates this risk.

STIG	Date
Apple OS X 10.10 (Yosemite) Workstation Security Technical Implementation Guide	2017-04-06

Details

Check Text ( C-60519r1_chk )
To check if the system is configured to send ICMP redirects, run the following command: sysctl net.inet.ip.redirect If the values are not set to '0', this is a finding.

Fix Text (F-65159r1_fix)
To configure the system to not send ICMP redirects, add the following line to /etc/sysctl.conf: net.inet.ip.redirect=0