The system must not accept source-routed IPv4 packets.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-22414	GEN003607	SV-37622r1_rule	ECSC-1	Medium

Description
Source-routed packets allow the source of the packet to suggest 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 handling of source-routed traffic destined to the system itself, not to traffic forwarded by the system to another system, such as when IPv4 forwarding is enabled and the system is functioning as a router.

Description

Source-routed packets allow the source of the packet to suggest 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 handling of source-routed traffic destined to the system itself, not to traffic forwarded by the system to another system, such as when IPv4 forwarding is enabled and the system is functioning as a router.

STIG	Date
Red Hat Enterprise Linux 5 Security Technical Implementation Guide	2016-12-16

Details

Check Text ( C-36821r1_chk )
Verify the system does not accept source-routed IPv4 packets. Procedure: # grep [01] /proc/sys/net/ipv4/conf/*/accept_source_route\|egrep "default\|all" If all of the resulting lines do not end with "0", this is a finding.

Fix Text (F-31659r1_fix)
Configure the system to not accept source-routed IPv4 packets. Edit /etc/sysctl.conf and add a setting for "net.ipv4.conf.all.accept_source_route=0" and "net.ipv4.conf.default.accept_source_route=0". Reload the sysctls. Procedure: # sysctl -p