The system must not accept ICMPv4 secure redirect packets on any interface.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-208855	OL6-00-000086	SV-208855r793640_rule		Medium

Description
Accepting "secure" ICMP redirects (from those gateways listed as default gateways) has few legitimate uses. It should be disabled unless it is absolutely required.

STIG	Date
Oracle Linux 6 Security Technical Implementation Guide	2021-12-03

Details

Check Text ( C-9108r357545_chk )
The status of the "net.ipv4.conf.all.secure_redirects" kernel parameter can be queried by running the following command: $ sysctl net.ipv4.conf.all.secure_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.ipv4.conf.all.secure_redirects /etc/sysctl.conf If the correct value is not returned, this is a finding.

Check Text ( C-9108r357545_chk )

The status of the "net.ipv4.conf.all.secure_redirects" kernel parameter can be queried by running the following command:

$ sysctl net.ipv4.conf.all.secure_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.ipv4.conf.all.secure_redirects /etc/sysctl.conf

If the correct value is not returned, this is a finding.

Fix Text (F-9108r357546_fix)
To set the runtime status of the "net.ipv4.conf.all.secure_redirects" kernel parameter, run the following command: # sysctl -w net.ipv4.conf.all.secure_redirects=0 If this is not the system's default value, add the following line to "/etc/sysctl.conf": net.ipv4.conf.all.secure_redirects = 0