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Cisco SDM Express
OL-7141-04
Chapter1 Cisco SDM Express
Supplementary Help
directed broadcast address, causing all the hosts on the target subnet to send
replies to the falsified source. By sending a continuous stream of such re quests,
the attacker can create a much larger stream of replies, which can completely
inundate the host whose address is being falsified.
Disabling IP directed broadcasts causes directed broadcasts that would ot herwise
be “exploded” into link-layer broadcasts at that interface to be dropped instead.
The configuration that will be delivered to the router to disable IP directed
broadcasts is as follows:
no ip directed-broadcast
You can undo this fix using the CiscoSD M Security Audit feature. To learn how,
see the Securi ty Audit online h elp in Cisco SDM. For more information, click
CiscoRouter and Security Device Manager.
Disable MOP Service
Cisco SDM Express will disable the Maintenance Operations Protocol (MOP) on
all Ethernet interfaces whenever possible. MOP is used to provide configuration
information to the router when communicating with DECNet networks. MOP is
vulnerable to various attacks.
The configuration that will be delivered to the router to disable the MOP service
on Ethernet interfaces is as follows:
no mop enabled
You can undo this fix using the CiscoSD M Security Audit feature. To learn how,
see the Securi ty Audit online h elp in Cisco SDM. For more information, click
CiscoRouter and Security Device Manager.
Disable IP Unreachables
Cisco SDM Express disables Internet Message Control Protocol (ICMP) host
unreachable messages whenever possible. ICMP supports IP traffic by relaying
information about paths, routes, and network conditions. ICMP host unre achable
messages are sent out if a router receives a nonbroadcast packet that uses an
unknown protocol, or if the router receives a packet that it is unable to deliver to
the ultimate destination because it knows of no route to the destination address.
These messages can be used by an attacker to gain network mapping information .