ZyXEL ADSL Router Prestige 660HW-D1 91-004-606002B Benutzerhandbuch

P-660H/HW-D Series User’s Guide

149

Chapter 9 Firewalls

Figure 84   Smurf Attack

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

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

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

Table 53   ICMP Commands That Trigger Alerts

5

REDIRECT

13

TIMESTAMP_REQUEST

14

TIMESTAMP_REPLY

17

ADDRESS_MASK_REQUEST

18

ADDRESS_MASK_REPLY

Table 54   Legal NetBIOS Commands

MESSAGE:

REQUEST:

POSITIVE:

VE:

RETARGET:

KEEPALIVE:

Table 55    Legal SMTP Commands

AUTH

DATA

EHLO

ETRN

EXPN

HELO

HELP

MAIL

NOOP

QUIT

RCPT

RSET

SAML

SEND

SOML 

TURN

VRFY