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The SUSE operating system must not be performing Internet Protocol version 4 (IPv4) packet forwarding unless the system is a router.


Finding ID Version Rule ID IA Controls Severity
V-235024 SLES-15-040380 SV-235024r622137_rule Medium
Routing protocol daemons are typically used on routers to exchange network topology information with other routers. If this software is used when not required, system network information may be unnecessarily transmitted across the network.
SUSE Linux Enterprise Server 15 Security Technical Implementation Guide 2022-12-07


Check Text ( C-38212r619341_chk )
Verify the SUSE operating system is not performing IPv4 packet forwarding, unless the system is a router.

Check to see if IPv4 forwarding is disabled using the following command:

> sudo sysctl net.ipv4.ip_forward
net.ipv4.ip_forward = 0

If the network parameter "ipv4.ip_forward" is not equal to "0" or nothing is returned, this is a finding.
Fix Text (F-38175r619342_fix)
Configure the SUSE operating system to not performing IPv4 packet forwarding by running the following command as an administrator:

> sudo sysctl -w net.ipv4.ip_forward=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.ip_forward=0" >> /etc/sysctl.d/99-stig.conf'

> sudo sysctl --system