Icmp Vulnerability; Illegal Commands (Netbios And Smtp); Figure 92 Smurf Attack; Table 64 Icmp Commands That Trigger Alerts - ZyXEL Communications Internet Security Appliance ZyWALL5UTM 4.0 User Manual

ZyWALL 5/35/70 Series User's Guide

Figure 92 Smurf Attack

10.4.2.1 ICMP Vulnerability

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

Table 64 ICMP Commands That Trigger Alerts

5
13
14
17
18

10.4.2.2 Illegal Commands (NetBIOS and SMTP)

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

Table 65 Legal NetBIOS Commands

MESSAGE:
REQUEST:
POSITIVE:
NEGATIVE:
RETARGET:
KEEPALIVE:
203
REDIRECT
TIMESTAMP_REQUEST
TIMESTAMP_REPLY
ADDRESS_MASK_REQUEST
ADDRESS_MASK_REPLY
Chapter 10 Firewalls