ZyXEL Communications P-660HW-T v2 - Manual (Page 142)

P-660HW-T v2 User’s Guide
142 Chapter 9 Firewalls
Figure 81 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:
9.4.2.2 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 49 ICMP Commands That Trigger Alerts
5 REDIRECT
13 TIMESTAMP_REQUEST
14 TIMESTAMP_REPLY
17 ADDRESS_MASK_REQUEST
18 ADDRESS_MASK_REPLY
Table 50 Legal NetBIOS Commands
MESSAGE:
REQUEST:
POSITIVE:
VE:
RETARGET:
KEEPALIVE:
Table 51 Legal SMTP Commands
AUTH DATA EHLO ETRN EXPN HELO HELP MAIL NOOP
QUIT RCPT RSET SAML SEND SOML TURN VRFY