The NSX-T Tier-0 Gateway must be configured to have Internet Control Message Protocol (ICMP) redirects disabled on all external interfaces.
Overview
| Finding ID | Version | Rule ID | IA Controls | Severity |
| V-251755 | T0RT-3X-000066 | SV-251755r856696_rule | CCI-002385 | medium |
| 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. Redirect ICMP messages are commonly used by attackers for network mapping and diagnosis. | ||||
| STIG | Date | |||
| VMware NSX-T Tier-0 Gateway RTR Security Technical Implementation Guide | 2022-09-01 | |||
Details
Check Text (C-251755r856696_chk)
If the Tier-0 Gateway is deployed in an Active/Active HA mode, this is Not Applicable.
From the NSX-T Manager web interface, go to Security >> Gateway Firewall >> Gateway Specific Rules, and choose each Tier-0 Gateway in the drop-down.
Review each Tier-0 Gateway Firewalls rules to verify one exists to drop ICMP redirects.
If a rule does not exist to drop ICMP redirects, this is a finding.
Fix Text (F-55146r810148_fix)
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 "ICMP Redirect", and then click "Apply".
Enable logging, under the "Applied To" field select the target Tier-0 Gateways, and then click "Publish" to enforce the new rule.
Note: A rule can also be created under Gateway Specific Rules to meet this requirement.