Protecting Against Smurf Attacks - Dell PowerConnect B-FCXs Configuration Manual

Protecting Against Denial of Service Attacks
Table 232
support.
TABLE 232
Feature
Smurf attack (ICMP attack) protection
TCP SYN attack protection
This chapter explains how to protect your Dell PowerConnect devices from Denial of Service (DoS)
attacks.
In a Denial of Service (DoS) attack, a router is flooded with useless packets, hindering normal
operation. Dell PowerConnect devices include measures for defending against two types of DoS
attacks Smurf attacks and TCP SYN attacks.

Protecting against Smurf attacks

A Smurf attack is a kind of DoS attack in which an attacker causes a victim to be flooded with
Internet Control Message Protocol (ICMP) echo (Ping) replies sent from another network.
Figure 174
FIGURE 174
1
Attacker sends ICMP echo requests to
broadcast address on Intermediary's
network, spoofing Victim's IP address
as the source
The attacker sends an ICMP echo request packet to the broadcast address of an intermediary
network. The ICMP echo request packet contains the spoofed address of a victim network as its
source. When the ICMP echo request reaches the intermediary network, it is converted to a Layer 2
broadcast and sent to the hosts on the intermediary network. The hosts on the intermediary
network then send ICMP replies to the victim network.
PowerConnect B-Series FCX Configuration Guide
53-1002266-01
lists individual Dell PowerConnect switches and the DoS protection features they
Supported DoS protection features
illustrates how a Smurf attack works.
How a Smurf attack floods a victim with ICMP replies
Attacker
2
If Intermediary has directed broadcast
forwarding enabled, ICPM echo requests
are broadcast to hosts on Intermediary's
network
Intermediary
PowerConnect B-Series FCX
Yes
Yes
3
The hosts on Intermediary's network
send replies to Victim, inundating Victim
with ICPM packets
Chapter
38
Victim
1339