The NSX Tier-0 Gateway Firewall must deny network communications traffic by default and allow network communications traffic by exception.

Severity	Group ID	Group Title	Version	Rule ID	Date	STIG Version
medium	V-265368	SRG-NET-000202-FW-000039	NT0F-4X-000016	SV-265368r994347_rule	2024-12-13	1

Description
To prevent malicious or accidental leakage of traffic, organizations must implement a deny-by-default security posture at the network perimeter. Such rulesets prevent many malicious exploits or accidental leakage by restricting the traffic to only known sources and only those ports, protocols, or services that are permitted and operationally necessary. As a managed boundary interface, the firewall must block all inbound and outbound network traffic unless a filter is installed to explicitly allow it. The allow filters must comply with the Ports, Protocols, and Services Management (PPSM) Category Assurance List (CAL) and Vulnerability Assessment (VA). Satisfies: SRG-NET-000202-FW-000039, SRG-NET-000205-FW-000040, SRG-NET-000235-FW-000133, SRG-NET-000364-FW-000031

Description

To prevent malicious or accidental leakage of traffic, organizations must implement a deny-by-default security posture at the network perimeter. Such rulesets prevent many malicious exploits or accidental leakage by restricting the traffic to only known sources and only those ports, protocols, or services that are permitted and operationally necessary. As a managed boundary interface, the firewall must block all inbound and outbound network traffic unless a filter is installed to explicitly allow it. The allow filters must comply with the Ports, Protocols, and Services Management (PPSM) Category Assurance List (CAL) and Vulnerability Assessment (VA). Satisfies: SRG-NET-000202-FW-000039, SRG-NET-000205-FW-000040, SRG-NET-000235-FW-000133, SRG-NET-000364-FW-000031

ℹ️ Check
From the NSX Manager web interface, go to Security >> Policy Management >> Gateway Firewall >> Gateway Specific Rules. Choose each Tier-0 Gateway in drop-down, then select Policy_Default_Infra Section >> Action. If the default_rule is set to "Allow", this is a finding.

✔️ Fix
From the NSX Manager web interface, go to Security >> Policy Management >> Gateway Firewall >> Gateway Specific Rules. Choose each Tier-0 Gateway in drop-down, then select Policy_Default_Infra Section >> Action. Change the Action to "Drop" or "Reject", and then click "Publish".