ZyXEL Communications ZYAIR, Руководство пользователя

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ZyAIR Wireless Gateway Series User’s Guide
Introduction to Firewalls 11-7
The only legal NetBIOS commands are the following - all others are illegal.
Table 11-3 Legal NetBIOS Commands
MESSAGE:
REQUEST:
POSITIVE:
NEGATIVE:
RETARGET:
KEEPALIVE:
All SMTP commands are illegal except for those displayed in the following tables.
Table 11-4 Legal SMTP Commands
AUTH DATA EHLO ETRN EXPN HELO HELP MAIL NOOP
QUIT RCPT RSET SAML SEND SOML TURN VRFY
Traceroute
Traceroute is a utility used to determine the path a packet takes between two endpoints. Sometimes when a
packet filter firewall is configured incorrectly an attacker can traceroute the firewall gaining knowledge of
the network topology inside the firewall.
4. Often, many DoS attacks also employ a technique known as "
IP Spoofing " as part of their attack. IP
Spoofing may be used to break into systems, to hide the hacker's identity, or to magnify the effect of the
DoS attack. IP Spoofing is a technique used to gain unauthorized access to computers by tricking a
router or firewall into thinking that the communications are coming from within the trusted network. To
engage in IP spoofing, a hacker must modify the packet headers so that it appears that the packets
originate from a trusted host and should be allowed through the router or firewall. The ZyAIR blocks all
IP Spoofing attempts.
11.5 Stateful Inspection
Stateful inspection means the ZyAIR records packet information, such as port number and source/destination
addresses and then allows or denies the response depending on your firewall rules.
The default rules allow LAN-to-WAN traffic and deny traffic initiated from WAN-to-LAN.