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1 icmp vulnerability, 2 illegal commands (netbios and smtp), Figure 103 smurf attack – ZyXEL Communications P-2608HWL-Dx Series User Manual

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P-2608HWL-Dx Series User’s Guide

192

Chapter 15 Firewalls

Figure 103 Smurf Attack

15.4.2.1 ICMP Vulnerability

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

15.4.2.2 Illegal Commands (NetBIOS and SMTP)

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 69 ICMP Commands That Trigger Alerts

5

REDIRECT

13

TIMESTAMP_REQUEST

14

TIMESTAMP_REPLY

17

ADDRESS_MASK_REQUEST

18

ADDRESS_MASK_REPLY

Table 70 Legal NetBIOS Commands

MESSAGE:

REQUEST:

POSITIVE:

VE:

RETARGET:

KEEPALIVE:

Table 71 Legal SMTP Commands

AUTH

DATA

EHLO

ETRN

EXPN

HELO

HELP

MAIL

NOOP

QUIT

RCPT

RSET

SAML

SEND

SOML

TURN

VRFY