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A firewall must be able to protect against or limit the effects of Denial of Service (DoS) attacks by ensuring RHEL 8 can implement rate-limiting measures on impacted network interfaces.


Finding ID Version Rule ID IA Controls Severity
V-230525 RHEL-08-040150 SV-230525r744029_rule Medium
DoS is a condition when a resource is not available for legitimate users. When this occurs, the organization either cannot accomplish its mission or must operate at degraded capacity. This requirement addresses the configuration of RHEL 8 to mitigate the impact of DoS attacks that have occurred or are ongoing on system availability. For each system, known and potential DoS attacks must be identified and solutions for each type implemented. A variety of technologies exists to limit or, in some cases, eliminate the effects of DoS attacks (e.g., limiting processes or establishing memory partitions). Employing increased capacity and bandwidth, combined with service redundancy, may reduce the susceptibility to some DoS attacks. Since version 0.6.0, "firewalld" has incorporated "nftables" as its backend support. Utilizing the limit statement in "nftables" can help to mitigate DoS attacks.
Red Hat Enterprise Linux 8 Security Technical Implementation Guide 2022-06-15


Check Text ( C-33194r744027_chk )
Verify "nftables" is configured to allow rate limits on any connection to the system with the following command:

Verify "firewalld" has "nftables" set as the default backend:

$ sudo grep -i firewallbackend /etc/firewalld/firewalld.conf

# FirewallBackend

If the "nftables" is not set as the "firewallbackend" default, this is a finding.
Fix Text (F-33169r744028_fix)
Configure "nftables" to be the default "firewallbackend" for "firewalld" by adding or editing the following line in "etc/firewalld/firewalld.conf":


Establish rate-limiting rules based on organization-defined types of DoS attacks on impacted network interfaces.