ZyXEL Communications P-334WT Support Notes page 21

Firewall FAQ
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the P-334WT Support
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General
1. What is a network firewall?
2. What makes P-334WT secure?
3. What are the basic types of firewalls?
4. What kind of firewall is the P-334WT?
5. Why do you need a firewall when your router has packet filtering and NAT built-in?
6. What is Denials of Service (DoS)attack?
7. What is Ping of Death attack?
8. What is Teardrop attack?
9. What is SYN Flood attack?
10. What is LAND attack?
11. What is Brute-force attack?
12. What is IP Spoofing attack?
13. Why traffic redirect/static/policy route be blocked by P-334WT?
1. What is a network firewall?
A firewall is a system or group of systems that enforces an access-control policy between two
networks. It may also be defined as a mechanism used to protect a trusted network from an untrusted
network. The firewall can be thought of two mechanisms. One to block the traffic, and the other to
permit traffic.
2. What makes P-334WT secure?
The P-334WT is pre-configured to automatically detect and thwart Denial of Service (DoS) attacks
such as Ping of Death, SYN Flood, LAND attack, IP Spoofing, etc. It also uses stateful packet
inspection to determine if an inbound connection is allowed through the firewall to the private LAN.
The P-334WT supports Network Address Translation (NAT), which translates the private local
addresses to one or multiple public addresses. This adds a level of security since the clients on the
private LAN are invisible to the Internet.
3. What are the basic types of firewalls?
Conceptually, there are three types of firewalls:
1. Packet Filtering Firewall
2. Application-level Firewall
3. Stateful Inspection Firewall
Packet Filtering Firewalls generally make their decisions based on the header information in
individual packets. These header information include the source, destination addresses and ports of
the packets.
Application-level Firewalls generally are hosts running proxy servers, which permit no traffic
directly between networks, and which perform logging and auditing of traffic passing through them.
A proxy server is an application gateway or circuit-level gateway that runs on top of general
operating system such as UNIX or Windows NT. It hides valuable data by requiring users to
communicate with secure systems by mean of a proxy. A key drawback of this device is
performance.