P-660H/HW-T Series User’ Guide
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Chapter 10 Firewalls
10.2.2 Application-level Firewalls
Application-level firewalls restrict access by serving as proxies for external servers. Since they
use programs written for specific Internet services, such as HTTP, FTP and telnet, they can
evaluate network packets for valid application-specific data. Application-level gateways have
a number of general advantages over the default mode of permitting application traffic directly
to internal hosts:
Information hiding prevents the names of internal systems from being made known via DNS
to outside systems, since the application gateway is the only host whose name must be made
known to outside systems.
Robust authentication and logging pre-authenticates application traffic before it reaches
internal hosts and causes it to be logged more effectively than if it were logged with standard
host logging. Filtering rules at the packet filtering router can be less complex than they would
be if the router needed to filter application traffic and direct it to a number of specific systems.
The router need only allow application traffic destined for the application gateway and reject
the rest.
10.2.3 Stateful Inspection Firewalls
Stateful inspection firewalls restrict access by screening data packets against defined access
rules. They make access control decisions based on IP address and protocol. They also
"inspect" the session data to assure the integrity of the connection and to adapt to dynamic
protocols. These firewalls generally provide the best speed and transparency, however, they
may lack the granular application level access control or caching that some proxies support.
See
for more information on stateful inspection.
Firewalls, of one type or another, have become an integral part of standard security solutions
for enterprises.
10.3 Introduction to ZyXEL’s Firewall
The Prestige firewall is a stateful inspection firewall and is designed to protect against Denial
of Service attacks when activated (in SMT menu 21.2 or in the web configurator). The
Prestige’s purpose is to allow a private Local Area Network (LAN) to be securely connected
to the Internet. The Prestige can be used to prevent theft, destruction and modification of data,
as well as log events, which may be important to the security of your network. The Prestige
also has packet filtering capabilities.
The Prestige is installed between the LAN and the Internet. This allows it to act as a secure
gateway for all data passing between the Internet and the LAN.
The Prestige has one DSL/ISDN port and one Ethernet LAN port, which physically separate
the network into two areas.
• The DSL/ISDN port connects to the Internet.
Summary of Contents for P-660H Series
Page 2: ......
Page 10: ...P 660H HW T Series User Guide 9 Customer Support ...
Page 32: ...P 660H HW T Series User Guide 31 List of Figures ...
Page 38: ...P 660H HW T Series User Guide 37 List of Tables ...
Page 42: ...P 660H HW T Series User Guide 41 Introduction to DSL ...
Page 62: ...P 660H HW T Series User Guide 61 Chapter 3 Wizard Setup for Internet Access ...
Page 90: ...P 660H HW T Series User Guide 89 Chapter 5 Wireless LAN ...
Page 132: ...P 660H HW T Series User Guide 131 Chapter 10 Firewalls ...
Page 162: ...P 660H HW T Series User Guide 161 Chapter 13 Remote Management Configuration ...
Page 176: ...P 660H HW T Series User Guide 175 Chapter 14 Universal Plug and Play UPnP ...
Page 182: ...P 660H HW T Series User Guide 181 Chapter 15 Logs Screens ...
Page 196: ...P 660H HW T Series User Guide 195 Chapter 16 Media Bandwidth Management Advanced Setup ...
Page 208: ...P 660H HW T Series User Guide 207 Chapter 17 Maintenance ...
Page 218: ...P 660H HW T Series User Guide 217 Chapter 19 Menu 1 General Setup ...
Page 222: ...P 660H HW T Series User Guide 221 Chapter 20 Menu 2 WAN Backup Setup ...
Page 226: ...P 660H HW T Series User Guide 225 Chapter 21 Menu 3 LAN Setup ...
Page 230: ...P 660H HW T Series User Guide 229 Chapter 22 Wireless LAN Setup ...
Page 236: ...P 660H HW T Series User Guide 235 Chapter 23 Internet Access ...
Page 250: ...P 660H HW T Series User Guide 249 Chapter 25 Static Route Setup ...
Page 254: ...P 660H HW T Series User Guide 253 Chapter 26 Bridging Setup ...
Page 270: ...P 660H HW T Series User Guide 269 Chapter 27 Network Address Translation NAT ...
Page 286: ...P 660H HW T Series User Guide 285 Chapter 29 Filter Configuration ...
Page 306: ...P 660H HW T Series User Guide 305 Chapter 32 System Information and Diagnosis ...
Page 318: ...P 660H HW T Series User Guide 317 Chapter 33 Firmware and Configuration File Maintenance ...
Page 324: ...P 660H HW T Series User Guide 323 Chapter 34 System Maintenance ...
Page 328: ...P 660H HW T Series User Guide 327 Chapter 35 Remote Management ...
Page 338: ...P 660H HW T Series User Guide 337 Chapter 36 IP Policy Routing ...
Page 342: ...P 660H HW T Series User Guide 341 Chapter 37 Call Scheduling ...
Page 358: ...P 660H HW T Series User Guide 357 Appendix A ...
Page 360: ...P 660H HW T Series User Guide 359 Appendix B ...
Page 384: ...P 660H HW T Series User Guide 383 Appendix D ...
Page 388: ...P 660H HW T Series User Guide 387 Appendix F ...
Page 394: ...P 660H HW T Series User Guide 393 Appendix G ...
Page 398: ...P 660H HW T Series User Guide 397 Appendix H ...
Page 401: ...P 660H HW T Series User Guide Appendix I 400 ...
Page 402: ...P 660H HW T Series User Guide 401 Appendix I ...
Page 456: ...P 660H HW T Series User Guide 455 Appendix M ...
