The system must ignore ICMPv6 redirects by default.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-38548	RHEL-06-000099	SV-50349r3_rule		Medium

Description
An illicit ICMP redirect message could result in a man-in-the-middle attack.

STIG	Date
Red Hat Enterprise Linux 6 Security Technical Implementation Guide	2015-05-26

Details

Check Text ( C-46106r3_chk )

If IPv6 is disabled, this is not applicable. The status of the "net.ipv6.conf.default.accept_redirects" kernel parameter can be queried by running the following command: $ sysctl net.ipv6.conf.default.accept_redirects The output of the command should indicate a value of "0". If this value is not the default value, investigate how it could have been adjusted at runtime, and verify it is not set improperly in "/etc/sysctl.conf". $ grep net.ipv6.conf.default.accept_redirects /etc/sysctl.conf If the correct value is not returned, this is a finding.

Fix Text (F-43496r1_fix)
To set the runtime status of the "net.ipv6.conf.default.accept_redirects" kernel parameter, run the following command: # sysctl -w net.ipv6.conf.default.accept_redirects=0 If this is not the system's default value, add the following line to "/etc/sysctl.conf": net.ipv6.conf.default.accept_redirects = 0