The Arista router 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-256034	ARST-RT-000550	SV-256034r882444_rule		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
Arista MLS EOS 4.2x Router Security Technical Implementation Guide	2023-01-17

Details

Check Text ( C-59710r882442_chk )

Review the device configuration to determine if controls have been defined to ensure the router does not send ICMP Redirect messages out to any external interfaces. Step 1: To verify the ACL is configured to determine the router does not send ICMP Redirect messages out to any external interfaces, execute the command "sh ip access-list". ip access-group DENY_REDIRECT deny icmp any any redirect permit ip any any Step 2: To verify the ACL is applied outbound on interface, execute the command "sh run int Eth YY". interface Ethernet 2 ip access-group DENY_REDIRECT out If ICMP Redirect messages are enabled on any external interfaces, this is a finding.

Fix Text (F-59653r882443_fix)
Step 1: Disable ICMP redirects on all external interfaces. ip access-group DENY_REDIRECT deny icmp any any redirect permit ip any any Step 2: Apply the ACL outbound on interfaces. interface Ethernet 2 description EXTERNAL INTERFACE ip access-group DENY_REDIRECT in