The system must not accept IPv4 source-routed packets by default.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-38529	RHEL-06-000089	SV-50330r1_rule		Medium

Description
Accepting source-routed packets in the IPv4 protocol has few legitimate uses. It should be disabled unless it is absolutely required.

STIG	Date
Red Hat Enterprise Linux 6 Security Technical Implementation Guide	2013-06-03

Details

Check Text ( C-46088r1_chk )
The status of the "net.ipv4.conf.default.accept_source_route" kernel parameter can be queried by running the following command: $ sysctl net.ipv4.conf.default.accept_source_route 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". If the correct value is not returned, this is a finding.

Check Text ( C-46088r1_chk )

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

$ sysctl net.ipv4.conf.default.accept_source_route

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

Fix Text (F-43478r1_fix)
To set the runtime status of the "net.ipv4.conf.default.accept_source_route" kernel parameter, run the following command: # sysctl -w net.ipv4.conf.default.accept_source_route=0 If this is not the system's default value, add the following line to "/etc/sysctl.conf": net.ipv4.conf.default.accept_source_route = 0