The Arista router must be configured to drop all fragmented Internet Control Message Protocol (ICMP) packets destined to itself.

Severity	Group ID	Group Title	Version	Rule ID	Date	STIG Version
medium	V-256017	SRG-NET-000205-RTR-000002	ARST-RT-000350	SV-256017r882393_rule	2025-02-20	2

Description
Fragmented ICMP packets can be generated by hackers for DoS attacks such as Ping O' Death and Teardrop. It is imperative that all fragmented ICMP packets are dropped.

ℹ️ Check
Review the access control list (ACL) or filter for the Arista router receive path. Verify it will drop all fragmented ICMP packets destined to itself. Step 1: To verify the ACL is configured to filter the fragmented ICMP packets destined to itself, execute the command "sh ip access-list". ip access-list ICMP_FRAGMENTS 10 deny ip any any fragments 20 permit ip any any Step 2: To verify the ACL is applied to the external interfaces, execute the command "sh run int Eth YY". interface ethernet 5 ip access-group ICMP_FRAGMENTS in If the Arista router is not configured with a receive-path filter to drop all fragmented ICMP packets, this is a finding. Note: If the platform does not support the receive path filter, verify all layer 3 interfaces have an ingress ACL to control what packets are allowed to be destined to the router for processing.

ℹ️ Check

Review the access control list (ACL) or filter for the Arista router receive path. Verify it will drop all fragmented ICMP packets destined to itself. Step 1: To verify the ACL is configured to filter the fragmented ICMP packets destined to itself, execute the command "sh ip access-list". ip access-list ICMP_FRAGMENTS 10 deny ip any any fragments 20 permit ip any any Step 2: To verify the ACL is applied to the external interfaces, execute the command "sh run int Eth YY". interface ethernet 5 ip access-group ICMP_FRAGMENTS in If the Arista router is not configured with a receive-path filter to drop all fragmented ICMP packets, this is a finding. Note: If the platform does not support the receive path filter, verify all layer 3 interfaces have an ingress ACL to control what packets are allowed to be destined to the router for processing.

✔️ Fix
Ensure all Arista routers have their receive path filter configured to drop all fragmented ICMP packets. Step 1: Configure the ACL to filter the fragmented ICMP packets destined to itself. LEAF-1A(config)#ip access-list ICMP_FRAGMENTS LEAF-1A(config-acl-ICMP_FRAGMENTS)# 10 deny ip any any fragments LEAF-1A(config-acl-ICMP_FRAGMENTS)# 20 permit ip any any LEAF-1A(config-acl-ICMP_FRAGMENTS)# exit Step 2: Apply the ACL to the external interfaces. LEAF-1A(config)#interface ethernet 5 LEAF-1A(config-if-Et5)# ip access-group ICMP_FRAGMENTS in

✔️ Fix

Ensure all Arista routers have their receive path filter configured to drop all fragmented ICMP packets. Step 1: Configure the ACL to filter the fragmented ICMP packets destined to itself. LEAF-1A(config)#ip access-list ICMP_FRAGMENTS LEAF-1A(config-acl-ICMP_FRAGMENTS)# 10 deny ip any any fragments LEAF-1A(config-acl-ICMP_FRAGMENTS)# 20 permit ip any any LEAF-1A(config-acl-ICMP_FRAGMENTS)# exit Step 2: Apply the ACL to the external interfaces. LEAF-1A(config)#interface ethernet 5 LEAF-1A(config-if-Et5)# ip access-group ICMP_FRAGMENTS in