Chapter 1 Cisco SDM Express
Supplementary Help
rules; some attacks are based on this. Disabling ICMP redirects will cause no operational impact to the network, and it eliminates this possible method of attack.
The configuration that will be delivered to the router to disable ICMP redirect messages is as follows:
no ip redirects
Disable IP Proxy ARP
Cisco SDM Express disables proxy Address Resolution Protocol (ARP) whenever possible. ARP is used by the network to convert IP addresses into MAC addresses. Normally ARP is confined to a single LAN, but a router can act as a proxy for ARP requests, making ARP queries available across multiple LAN segments. Because proxy ARP breaks the LAN security barrier, use it only between two LANs with an equal security level, and only when necessary.
The configuration that will be delivered to the router to disable proxy ARP is as follows:
no ip
You can undo this fix using the Cisco SDM Security Audit feature. To learn how, see the Security Audit online help in Cisco SDM. For more information, click Cisco Router and Security Device Manager.
Disable IP Directed Broadcast
Cisco SDM Express disables IP directed broadcasts whenever possible. An IP directed broadcast is a datagram sent to the broadcast address of a subnet to which the sending machine is not directly attached. The directed broadcast is routed through the network as a unicast packet until it arrives at the target subnet, where it is converted into a
IP directed broadcasts are used in the extremely common and popular “smurf”
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