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.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-230525	RHEL-08-040150	SV-230525r599732_rule		Medium

Description
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.

Description

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.

STIG	Date
Red Hat Enterprise Linux 8 Security Technical Implementation Guide	2020-11-25

Details

Check Text ( C-33194r568321_chk )
Verify "nftables" is configured to allow rate limits on any connection to the system with the following commands: Check that the "nftables.service" is active and running: $ sudo systemctl status nftables.service nftables.service - Netfilter Tables Loaded: loaded (/usr/lib/systemd/system/nftables.service; enabled; vendor preset: disabled) Active: active (running) Verify "firewalld" has "nftables" set as the default backend: $ sudo grep -i firewallbackend /etc/firewalld/firewalld.conf # FirewallBackend FirewallBackend=nftables If the "nftables" is not active, running and set as the "firewallbackend" default, this is a finding.

Check Text ( C-33194r568321_chk )

Verify "nftables" is configured to allow rate limits on any connection to the system with the following commands:

Check that the "nftables.service" is active and running:

$ sudo systemctl status nftables.service

nftables.service - Netfilter Tables
Loaded: loaded (/usr/lib/systemd/system/nftables.service; enabled; vendor preset: disabled)
Active: active (running)

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

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

# FirewallBackend
FirewallBackend=nftables

If the "nftables" is not active, running and set as the "firewallbackend" default, this is a finding.

Fix Text (F-33169r568322_fix)
Install "nftables" packages onto the host with the following commands: $ sudo yum install nftables.x86_64 1:0.9.0-14.el8 Configure the "nftables" service to automatically start after reboot with the following command: $ sudo systemctl enable nftables.service Configure "nftables" to be the default "firewallbackend" for "firewalld" by adding or editing the following line in "etc/firewalld/firewalld.conf": FirewallBackend=nftables Establish rate-limiting rules based on organization-defined types of DoS attacks on impacted network interfaces.

Fix Text (F-33169r568322_fix)

Install "nftables" packages onto the host with the following commands:

$ sudo yum install nftables.x86_64 1:0.9.0-14.el8

Configure the "nftables" service to automatically start after reboot with the following command:

$ sudo systemctl enable nftables.service

Configure "nftables" to be the default "firewallbackend" for "firewalld" by adding or editing the following line in "etc/firewalld/firewalld.conf":

FirewallBackend=nftables

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