CISC-RT-000470 - The Cisco BGP router must be configured to enable the Generalized TTL Security Mechanism (GTSM).

Information

As described in RFC 3682, GTSM is designed to protect a router's IP-based control plane from denial of service (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 routers.

GTSM is based on the fact that the vast majority of control plane peering is established between adjacent routers; 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

Configure TTL security on all external BGP neighbors as shown in the example below:

R1(config)#router bgp xx
R1(config-router)#neighbor x.1.1.9 ttl-security hops 1
R1(config-router)#neighbor x.2.1.7 ttl-security hops 1

Item Details

Audit Name: DISA Cisco IOS XE Router RTR STIG v3r5

Category: SYSTEM AND COMMUNICATIONS PROTECTION

Plugin: Cisco

Control ID: ba56322e10c881225bafcf985a478b77b56ef1bb7fa869d2a54b9a1335218b2f

Detections

Analytics

CISC-RT-000470 - The Cisco BGP router must be configured to enable the Generalized TTL Security Mechanism (GTSM).

Information

Solution

See Also

Item Details