Cisco IOS DOS

Cisco routers are configured to process and accept Internet Protocol version 4 (IPv4) packets by default. When a Cisco IOS device is sent a specially crafted sequence of IPv4 packets (with protocol type 53 - SWIPE, 55 - IP Mobility, 77 - Sun ND, or 103 - Protocol Independent Multicast - PIM), the router will stop processing inbound traffic on that interface.

You can configure how Cisco IOS DOS attacks should be handled.

Note: You cannot enable CISCO IOS DOS PIM protection in SmartDefense, when the PIM-SM multicast routing protocol is enabled. For information on disabling the PIM-SM protocol, refer to the Embedded NGX CLI Reference Guide.

Cisco IOS DOS

In this field…	Do this…
Action	Specify what action to take when a Cisco IOS DOS attack occurs, by selecting one of the following: Block. Block the attack. This is the default. None. No action.
Track	Specify whether to log Cisco IOS DOS attacks, by selecting one of the following: Log. Log the attack. This is the default. None. Do not log the attack.
Number of Hops to Protect	Type the number of hops from the enforcement module that Cisco routers should be protected. The default value is 10.
Action Protection for SWIPE - Protocol 53 / IP Mobility - Protocol 55 / SUN-ND - Protocol 77 / PIM - Protocol 103	Specify what action to take when an IPv4 packet of the specific protocol type is received, by selecting one of the following: Block. Drop the packet. This is the default. None. No action.