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The Cisco router must be configured to have Cisco Express Forwarding enabled.


Overview

Finding ID Version Rule ID IA Controls Severity
V-229030 CISC-RT-000235 SV-229030r531380_rule Medium
Description
The Cisco Express Forwarding (CEF) switching mode replaces the traditional Cisco routing cache with a data structure that mirrors the entire system routing table. Because there is no need to build cache entries when traffic starts arriving for new destinations, CEF behaves more predictably when presented with large volumes of traffic addressed to many destinations—such as a SYN flood attacks that. Because many SYN flood attacks use randomized source addresses to which the hosts under attack will reply to, there can be a substantial amount of traffic for a large number of destinations that the router will have to handle. Consequently, routers configured for CEF will perform better under SYN floods directed at hosts inside the network than routers using the traditional cache.
STIG Date
Cisco IOS Router RTR Security Technical Implementation Guide 2022-09-14

Details

Check Text ( C-31345r802613_chk )
Review the router to verify that CEF is enabled.

IPv4 Example: ip cef
IPv6 Example: ipv6 cef
Fix Text (F-31322r802614_fix)
Enable CEF

IPv4 Example: ip cef
IPv6 Example: ipv6 cef