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V-217289

CAT II (Medium)

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

Rule ID

SV-217289r991589_rule

STIG

SLES 12 Security Technical Implementation Guide

Version

V3R2

CCIs

V-77489

Discussion

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.

Check Content

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

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