STIGQter: STIG Summary: Arista MLS EOS 4.X Router Security Technical Implementation Guide Version: 2 Release: 2 Benchmark Date: 02 Apr 2025:

The Arista router must be configured to have Internet Control Message Protocol (ICMP) unreachable notifications disabled on all external interfaces.

DISA Rule

SV-256032r882438_rule

Vulnerability Number

V-256032

Group Title

SRG-NET-000362-RTR-000113

Rule Version

ARST-RT-000530

Severity

CAT II

CCI(s)

• CCI-002385 - Protect against or limit the effects of organization-defined types of denial of service events.

Weight

10

Fix Recommendation

Disable ICMP unreachable notifications on all external interfaces.

Step 1: The Arista router can be configured to filter out the ICMP Unreachable for (Type 3) code 0 (Network unreachable) IPv4 and IPv6 packets with the following command:

router(config)#ip icmp rate-limit-unreachable 0
router(config)#ipv6 icmp rate-limit-unreachable 0

Step 2: The Arista router can be configured to filter out the ICMP Unreachable for (Type 3) code 1 (Network unreachable) IPv4 and IPv6 packets with the following command:

router(config)#ip access-list BLK-ICMP-Unreachables
10 deny icmp any any host-unreachable
20 permit ip any any
!

Step 3: This would need to be applied on the egress interface (for example as in et1 below):

router(config)#interface ethernet1
no routerport
ip address 32.1.1.12/24
ip access-group BLK-ICMP-Unreachables out
!

Check Contents

Review the device configuration to determine if controls have been defined to ensure the router does not send ICMP unreachable notifications out to any external interfaces.

Step 1: To verify the ACL is configured to determine the router does not send ICMP unreachable notifications out to any external interfaces, execute the command "sh ip access-list".

ip access-group DENY_ICMP_UNREACHABLE
deny icmp any any unreachable
permit ip any any

Step 2: To verify the ACL is applied outbound on interfaces, execute the command "sh run int Eth YY".

interface Ethernet 2
ip access-group DENY_ICMP_UNREACHABLE out

If ICMP unreachable notifications are enabled on any external interfaces, this is a finding.

Vulnerability Number

V-256032

Documentable

False

Rule Version

ARST-RT-000530

Severity Override Guidance

Review the device configuration to determine if controls have been defined to ensure the router does not send ICMP unreachable notifications out to any external interfaces.

Step 1: To verify the ACL is configured to determine the router does not send ICMP unreachable notifications out to any external interfaces, execute the command "sh ip access-list".

ip access-group DENY_ICMP_UNREACHABLE
deny icmp any any unreachable
permit ip any any

Step 2: To verify the ACL is applied outbound on interfaces, execute the command "sh run int Eth YY".

interface Ethernet 2
ip access-group DENY_ICMP_UNREACHABLE out

If ICMP unreachable notifications are enabled on any external interfaces, this is a finding.

Check Content Reference

M

Target Key

5513