The RUCKUS ICX router must be configured to have Internet Control Message Protocol (ICMP) mask replies disabled on all external interfaces.
Overview
| Finding ID | Version | Rule ID | IA Controls | Severity |
| V-273632 | RCKS-RTR-000650 | SV-273632r1110938_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. Mask Reply ICMP messages are commonly used by attackers for network mapping and diagnosis. | ||||
| STIG | Date | |||
| RUCKUS ICX Router Security Technical Implementation Guide | 2025-06-03 | |||
Details
Check Text (C-273632r1110938_chk)
Review configuration to determine whether outgoing ICMP mask replies are blocked on external interfaces.
enable egress-acl-on-cpu-traffic
ip access-list extended BLOCK_ICMP_OUT
sequence 10 deny icmp any any unreachable
sequence 20 deny icmp any any mask-reply
sequence 30 permit ip any any
interface ethernet 1/1/1
ip address x.0.1.2 255.255.255.252
ip access-group BLOCK_ICMP_OUT out
!
If outgoing ICMP mask replies are not blocked on external interfaces, this is a finding.
Fix Text (F-77628r1110785_fix)
Configure ACL to block ICMP mask replies.
ICX(config)#enable egress-acl-on-cpu-traffic
ICX(config)#ip access ext BLOCK_ICMP_OUT
ICX(config-ext-ipacl-BLOCK_ICMP_OUT)#deny icmp any any unreachable
ICX(config-ext-ipacl-BLOCK_ICMP_OUT)#deny icmp any any mask-reply
ICX(config-ext-ipacl-BLOCK_ICMP_OUT)#permit ip any any
Apply ACL to external interface.
ICX(config)#interface ethernet 1/1/1
ICX(config-if-e1000-1/1/1)#ip access-group BLOCK_ICMP_OUT out