The NSX-T Tier-0 Gateway must be configured to have Internet Control Message Protocol (ICMP) mask replies disabled on all external interfaces.
An XCCDF Rule
Description
The ICMP supports IP traffic by relaying information about paths, routes, and network conditions. Routers automatically send ICMP messages under a wide variety of conditions. Mask Reply ICMP messages are commonly used by attackers for network mapping and diagnosis.
- ID
- SV-251754r856695_rule
- Version
- T0RT-3X-000065
- Severity
- Medium
- References
- Updated
Remediation Templates
A Manual Procedure
To configure a shared rule to drop ICMP unreachable messages do the following:
From the NSX-T Manager web interface, go to Security >> Gateway Firewall >> All Shared Rules.
Click "Add Rule" (Add a policy first if needed), under "Services" select the custom service that identifies ICMP mask replies, and then click "Apply".