Allied Telesis AT-S63 - Manual (Page 358)

Chapter 21: Denial of Service Defense Commands
358 Section II: Advanced Operations
SET DOS PINGOFDEATH
Syntax
set dos pingofdeath port= port state=enable|disable
[mirroring=yes|no|on|off|true|false|enabled|disabled]
Parameters
port Specifies the switch ports on which to enable or disable
the Ping of Death defense. You can specify more than
one port at a time.
state Specifies the state of the IP Option defense. The
options are:
enable Activates the defense.
disable Deactivates the defense. This is the default.
mirroring Specifies whether the examined traffic is copied to a
mirror port. Options are:
yes, on, true Traffic is mirrored. These values are
enabled equivalent.
no, off, false Traffic is not mirrored. This is the
disabled default. These values are equivalent.
Description
This command activates and deactivates the Ping of Death DoS defense.
In this DoS, an attacker sends an oversized, fragmented Ping packet to
the victim, which, if lacking a policy for handling oversized packets, may
freeze.
To defend against this form of attack, a switch port searches for the last
fragment of a fragmented Ping request and examines its offset to
determine if the packet size is greater than 63,488 bits. If it is, the fragment
is forwarded to the switch’s CPU for final packet size determination. If the
switch determines that the packet is oversized, the following occurs:
ˆ The switch sends a trap to the management stations.
ˆ The switch blocks all traffic on the port for one minute.