What Kind Of Firewall Is The P-660; Why Do You Need A Firewall When Your Router Has Packet Filtering And Nat Built-In; What Is Denials Of Service (Dos) Attack - ZyXEL Communications P-660R-T1 Support Notes

adapt to dynamic protocols. The flexible nature of Stateful Inspection firewalls
generally provides the best speed and transparency, however, they may lack the
granular application level access control or caching that some proxies support.

4. What kind of firewall is the P-660?

1. The P-660's firewall inspects packets contents and IP headers. It is applicable
to all protocols, that understands data in the packet is intended for other layers,
from network layer up to the application layer.
2. The P-660's firewall performs stateful inspection. It takes into account the
state of connections it handles so that, for example, a legitimate incoming
packet can be matched with the outbound request for that packet and allowed
in. Conversely, an incoming packet masquerading as a response to a
nonexistent outbound request can be blocked.
3. The P-660's firewall uses session filtering, i.e., smart rules, that enhance the
filtering process and control the network session rather than control individual
packets in a session.
4. The P-660's firewall is fast. It uses a hashing function to search the matched
session cache instead of going through every individual rule for a packet.
5. The P-660's firewall provides email service to notify you for routine reports
and when alerts occur.
5. Why do you need a firewall when your router has packet filtering and NAT
built-in?
With the spectacular growth of the Internet and online access, companies that do
business on the Internet face greater security threats. Although packet filter and NAT
restrict access to particular computers and networks, however, for the other
companies this security may be insufficient, because packets filters typically cannot
maintain session state. Thus, for greater security, a firewall is considered.

6. What is Denials of Service (DoS) attack?

Denial of Service (DoS) attacks are aimed at devices and networks with a connection
to the Internet. Their goal is not to steal information, but to disable a device or
network so users no longer have access to network resources.
There are four types of DoS attacks:
1. Those that exploits bugs in a TCP/IP implementation such as Ping of Death
and Teardrop.
2. Those that exploits weaknesses in the TCP/IP specification such as SYN
Flood and LAND Attacks.
3. Brute-force attacks that flood a network with useless data such as Smurf
attack.
All contents copyright © 2005 ZyXEL Communications Corporation.
P-660 series Support Notes
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