User manual ZYXEL P-660H

[. . . ] P-660H/HW-D Series ADSL2+ 4-port Gateway User's Guide Version 3. 40 Edition 1 3/2006 P-660H/HW-D Series User's Guide Copyright Copyright © 2006 by ZyXEL Communications Corporation. The contents of this publication may not be reproduced in any part or as a whole, transcribed, stored in a retrieval system, translated into any language, or transmitted in any form or by any means, electronic, mechanical, magnetic, optical, chemical, photocopying, manual, or otherwise, without the prior written permission of ZyXEL Communications Corporation. Published by ZyXEL Communications Corporation. All rights reserved. Disclaimer ZyXEL does not assume any liability arising out of the application or use of any products, or software described herein. [. . . ] A firewall is one of the mechanisms used to establish a network security perimeter in support of a network security policy. It should never be the only mechanism or method employed. For a firewall to guard effectively, you must design and deploy it appropriately. This requires integrating the firewall into a broad information-security policy. In addition, specific policies must be implemented within the firewall itself. Refer to Section 10. 5 on page 159 to configure default firewall settings. Refer to Section 10. 6 on page 160 to view firewall rules. Refer to Section 10. 6. 1 on page 162 to configure firewall rules. Refer to Section 10. 6. 2 on page 165 to configure a custom service. Refer to Section 10. 10. 3 on page 175 to configure firewall thresholds. 9. 2 Types of Firewalls There are three main types of firewalls: · Packet Filtering Firewalls · Application-level Firewalls · Stateful Inspection Firewalls 9. 2. 1 Packet Filtering Firewalls Packet filtering firewalls restrict access based on the source/destination computer network address of a packet and the type of application. Chapter 9 Firewalls 144 P-660H/HW-D Series User's Guide 9. 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. 9. 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 Section 9. 5 on page 150 for more information on stateful inspection. Firewalls, of one type or another, have become an integral part of standard security solutions for enterprises. 9. 3 Introduction to ZyXEL's Firewall The ZyXEL Device firewall is a stateful inspection firewall and is designed to protect against Denial of Service attacks when activated. The ZyXEL Device's purpose is to allow a private Local Area Network (LAN) to be securely connected to the Internet. The ZyXEL Device 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. [. . . ] 4 Under Java permissions make sure that a safety level is selected. 5 Click OK to close the window. 347 Appendix M Pop-up Windows, JavaScripts and Java Permissions P-660H/HW-D Series User's Guide Figure 197 Security Settings - Java JAVA (Sun) 1 From Internet Explorer, click Tools, Internet Options and then the Advanced tab. 2 make sure that Use Java 2 for <applet> under Java (Sun) is selected. 3 Click OK to close the window. Appendix M Pop-up Windows, JavaScripts and Java Permissions 348 P-660H/HW-D Series User's Guide Figure 198 Java (Sun) 349 Appendix M Pop-up Windows, JavaScripts and Java Permissions P-660H/HW-D Series User's Guide APPENDIX N Triangle Route The Ideal Setup When the firewall is on, your Prestige acts as a secure gateway between your LAN and the Internet. [. . . ]