UCF STIG Viewer Logo

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


Finding ID Version Rule ID IA Controls Severity
V-235016 SLES-15-040320 SV-235016r622137_rule Medium
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.
SUSE Linux Enterprise Server 15 Security Technical Implementation Guide 2022-12-07


Check Text ( C-38204r619317_chk )
Verify the SUSE operating system does not accept IPv4 source-routed packets by default.

Check the value of the default IPv4 accept source route variable with the following command:

> sudo sysctl net.ipv4.conf.default.accept_source_route
net.ipv4.conf.default.accept_source_route = 0

If the network parameter "ipv4.conf.default.accept_source_route" is not equal to "0" or nothing is returned, this is a finding.
Fix Text (F-38167r619318_fix)
Configure the SUSE operating system to disable IPv4 default source routing by running the following command as an administrator:

> sudo sysctl -w net.ipv4.conf.default.accept_source_route=0

If "0" is not the system's default value, add or update the following line in "/etc/sysctl.d/99-stig.conf":

> sudo sh -c 'echo "net.ipv4.conf.default.accept_source_route=0" >> /etc/sysctl.d/99-stig.conf'

> sudo sysctl --system