ZyXEL ADSL Prestige 660HW-61 91-004-361001 Manual Do Utilizador

Prestige 660H/HW Series User’s Guide

135 

Chapter 12 Firewalls

Figure 56   Smurf Attack

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

Table 38   ICMP Commands That Trigger Alerts

5

REDIRECT

13

TIMESTAMP_REQUEST

14

TIMESTAMP_REPLY

17

ADDRESS_MASK_REQUEST

18

ADDRESS_MASK_REPLY

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

Table 39   Legal NetBIOS Commands

MESSAGE:

REQUEST:

POSITIVE:

VE:

RETARGET:

KEEPALIVE:

All SMTP commands are illegal except for those displayed in the following tables.