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V-254228

CAT II (Medium)

Nutanix AOS must be configured to use syncookies to limit denial-of-service (DoS) attacks.

Rule ID

SV-254228r958528_rule

STIG

Nutanix AOS 5.20.x OS Security Technical Implementation Guide

Version

V1R2

CCIs

CCI-001095

Discussion

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. Managing excess capacity ensures that sufficient capacity is available to counter flooding attacks. Employing increased capacity and service redundancy may reduce the susceptibility to some DoS attacks. Managing excess capacity may include, for example, establishing selected usage priorities, quotas, or partitioning.

Check Content

Confirm Nutanix AOS is configured to use syncookies.

$ sysctl net.ipv4.tcp_syncookies 
net.ipv4.tcp_syncookies = 1 

If the value is not "1", this is a finding. 

Check the saved value of TCP syncookies with the following command: 

$ sudo grep -i net.ipv4.tcp_syncookies /etc/sysctl.conf /etc/sysctl.d/* | grep -v '#' 

If no output is returned, this is a finding.

Fix Text

Configure Nutanix AOS to use TCP syncookies by running the following command: 

$ sudo sysctl -w net.ipv4.tcp_syncookies=1 

If "1" is not the system's default value, add or update the following line in "/etc/sysctl.conf": 

net.ipv4.tcp_syncookies = 1