Icmp Vulnerability; Illegal Commands (Netbios And Smtp); Figure 61 Smurf Attack; Table 45 Icmp Commands That Trigger Alerts - ZyXEL Communications ZyWALL 5 User Manual

ZyWALL 5 User's Guide

Figure 61 Smurf Attack

9.4.2.1 ICMP Vulnerability

ICMP is an error-reporting protocol that works in concert with IP. The following ICMP types
trigger an alert:

Table 45 ICMP Commands That Trigger Alerts

5
13
14
17
18

9.4.2.2 Illegal Commands (NetBIOS and SMTP)

The only legal NetBIOS commands are the following - all others are illegal.

Table 46 Legal NetBIOS Commands

MESSAGE:
REQUEST:
POSITIVE:
NEGATIVE:
RETARGET:
KEEPALIVE:
156
REDIRECT
TIMESTAMP_REQUEST
TIMESTAMP_REPLY
ADDRESS_MASK_REQUEST
ADDRESS_MASK_REPLY
Chapter 9 Firewalls