The RUCKUS ICX BGP router must be configured to limit the prefix size on any inbound route advertisement to /24 or the least significant prefixes issued to the customer.
Overview
| Finding ID | Version | Rule ID | IA Controls | Severity |
| V-273635 | RCKS-RTR-000680 | SV-273635r1110897_rule | CCI-002385 | low |
| Description | ||||
| The effects of prefix de-aggregation can degrade router performance due to the size of routing tables and also result in black-holing legitimate traffic. Initiated by an attacker or a misconfigured router, prefix de-aggregation occurs when the announcement of a large prefix is fragmented into a collection of smaller prefix announcements. | ||||
| STIG | Date | |||
| RUCKUS ICX Router Security Technical Implementation Guide | 2025-06-03 | |||
Details
Check Text (C-273635r1110897_chk)
This requirement is not applicable for the DODIN Backbone.
Review the router configuration to determine if it is compliant with this requirement.
1. Verify a route filter has been configured to reject prefixes longer than /24, or the least significant prefixes issued to the customers as shown in the example below:
ip prefix-list FILTER_PREFIX_LENGTH seq 5 permit 0.0.0.0/0 ge 8 le 24
ip prefix-list FILTER_PREFIX_LENGTH seq 10 deny 0.0.0.0/0 le 32
2. Verify prefix filtering has been applied to each eBGP peer as shown in the following example:
router bgp
neighbor x.1.1.9 remote-as yy
neighbor x.1.1.9 prefix-list FILTER_PREFIX_LENGTH in
If the router is not configured to limit the prefix size on any inbound route advertisement to /24, or the least significant prefixes issued to the customer, this is a finding.
Fix Text (F-77631r1110772_fix)
This requirement is not applicable for the DODIN Backbone.
Configure the router to limit the prefix size on any route advertisement to /24 or the least significant prefixes issued to the customer.
1. Configure a prefix list to reject any prefix that is longer than /24.
ICX(config)#ip prefix-list FILTER_PREFIX_LENGTH permit 0.0.0.0/0 ge 8 le 24
ICX(config)#ip prefix-list FILTER_PREFIX_LENGTH deny 0.0.0.0/0 le 32
2. Apply the prefix list to all eBGP peers as shown in the example below:
ICX(config)#router bgp
ICX(config-bgp-router)#neighbor x.1.1.9 prefix-list FILTER_PREFIX_LENGTH in