The SUSE operating system must not forward Internet Protocol version 4 (IPv4) source-routed packets.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-77487	SLES-12-030360	SV-92183r1_rule		Medium

Description
Source-routed packets allow the source of the packet to suggest that routers forward the packet along a different path than configured on the router, which can be used to bypass network security measures. This requirement applies only to the forwarding of source-routed traffic, such as when IPv4 forwarding is enabled and the system is functioning as a router.

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

Details

Check Text ( C-77047r1_chk )
Verify the SUSE operating system does not accept IPv4 source-routed packets. Check the value of the accept source route variable with the following command: # sysctl net.ipv4.conf.all.accept_source_route net.ipv4.conf.all.accept_source_route = 0 If the returned line does not have a value of "0" this is a finding.

Fix Text (F-84129r1_fix)
Configure the SUSE operating 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.accept_source_route = 0 Run the following command to apply this value: # sysctl --system