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


Overview

Finding ID Version Rule ID IA Controls Severity
V-77489 SLES-12-030370 SV-92185r3_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-77049r1_chk )
Verify the SUSE operating system does not accept IPv4 source-routed packets by default.

Check the value of the default accept source route variable with the following command:

# sysctl net.ipv4.conf.default.accept_source_route
net.ipv4.conf.default.accept_source_route = 0

If the returned line does not have a value of "0" this is a finding.
Fix Text (F-84131r3_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.default.accept_source_route = 0

Run the following command to apply this value:

# sysctl --system