Firewall Faq; General; What Is A Network Firewall; What Makes P-663Hn-51 Secure - ZyXEL Communications P-663HN-51 Support Notes

Firewall FAQ

General

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-663HN-51 secure?

DoS Prevention
Stateful Packet Inspection
ACL between outgoing and incoming.
At least 20 ACL rules
Protocol and Generic Packet Filter
SIP ALG

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 headers 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
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P-663HN-51 Support Notes
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