ufw Must rate-limit network interfaces

Description

The operating system must configure the uncomplicated firewall to rate-limit impacted network interfaces. Check all the services listening to the ports with the following command:

$ sudo ss -l46ut
Netid State Recv-Q Send-Q Local Address:Port Peer Address:Port Process
tcp LISTEN 0 128 [::]:ssh [::]:*

For each entry, verify that the ufw is configured to rate limit the service ports with the following command:

$ sudo ufw status

If any port with a state of "LISTEN" is not marked with the "LIMIT" action, run the following command, replacing "service" with the service that needs to be rate limited:

$ sudo ufw limit "service"

Rate-limiting can also be done on an interface. An example of adding a rate-limit on the eth0 interface follows:

$ sudo ufw limit in on eth0

Rationale

This requirement addresses the configuration of the operating system 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 exist 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.