Nokia IP60 User Manual page 291

Small PMTU
Small PMTU (Packet MTU) is a bandwidth attack in which the client fools the server into sending large
amounts of data using small packets. Each packet has a large overhead that creates a "bottleneck" on the
server.
You can protect against this attack by specifying a minimum packet size for data sent over the Internet.
Table 70: Small PMTU Fields
In this field... Do this...
Specify what action to take when a packet is smaller than the Minimal MTU
Action
Size threshold, by selecting one of the following:
Block. Block the packet.
None. No action. This is the default.
Specify whether to issue logs for packets are smaller than the Minimal MTU
Track
Size threshold, by selecting one of the following:
Log. Issue logs. This is the default.
None. Do not issue logs.
Minimal MTU Type the minimum value allowed for the MTU field in IP packets sent by a
Size client.
An overly small value will not prevent an attack, while an overly large value
might degrade performance and cause legitimate requests to be dropped.
The default value is 300.
Chapter 13: Using SmartDefense
SmartDefense Categories
291