ZyXEL Communications P-660HW-Tx v3 Series User Manual page 228

Chapter 12 Packet Filter
• The 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 non-existent outbound
request can be blocked.
• The 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.
• The firewall provides e-mail service to notify you of routine reports and when
alerts occur.
When To Use The Firewall
To prevent DoS attacks and prevent hackers cracking your network.
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A range of source and destination IP addresses as well as port numbers can be
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specified within one firewall rule making the firewall a better choice when complex
rules are required.
To selectively block/allow inbound or outbound traffic between inside host/
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networks and outside host/networks. Remember that filters cannot distinguish
traffic originating from an inside host or an outside host by IP address.
The firewall performs better than filtering if you need to check many rules.
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Use the firewall if you need routine e-mail reports about your system or need to
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be alerted when attacks occur.
The firewall can block specific URL traffic that might occur in the future. The URL
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can be saved in an Access Control List (ACL) database.
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P-660HW-Tx v3 Series User's Guide