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1.28 CISC-RT-000470

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Information

The Cisco BGP switch must be configured to check whether a single-hop eBGP peer is directly connected.

GROUP ID: V-221101
RULE ID: SV-221101r999710

As described in RFC 3682, GTSM is designed to protect a switch's IP-based control plane from DoS attacks. Many attacks focused on CPU load and line-card overload can be prevented by implementing GTSM on all Exterior Border Gateway Protocol-speaking switches.

GTSM is based on the fact that the vast majority of control plane peering is established between adjacent switches; that is, the Exterior Border Gateway Protocol peers are either between connecting interfaces or between loopback interfaces. Since TTL spoofing is considered nearly impossible, a mechanism based on an expected TTL value provides a simple and reasonably robust defense from infrastructure attacks based on forged control plane traffic.

Solution

Remove the command that disables checking whether a single-hop eBGP peer is directly connected for all external BGP neighbors as shown in the example below:

SW1(config)# router bgp xx
SW1(config-router)# neighbor x.1.12.2
SW1(config-router-neighbor)# no disable-connected-check
SW1(config-router-neighbor)# end

See Also

https://workbench.cisecurity.org/benchmarks/22581

Item Details

Category: SYSTEM AND COMMUNICATIONS PROTECTION

References: 800-53|SC-5, CAT|III, CSCv7|14.4, Rule-ID|SV-221101r999710_rule, STIG-ID|CISC-RT-000470, Vuln-ID|V-221101

Plugin: Cisco

Control ID: a3297fc27846cede818020220ccbac36e2fc42b433f4e6d6df8da543c7333e2b