Working with IP ﬁlters and ﬁlter sets | Netopia R3100 manual

15-12 User’s Reference Guide

Disadvantages of ﬁlters

Although using ﬁlter sets can greatly enhance network security, there are disadvantages:

■Filters are complex. Combining them in ﬁlter sets introduces subtle interactions, increasing the likelihood of implementation errors.

■Enabling a large number of ﬁlters can have a negative impact on performance. Processing of packets will take longer if they have to go through many checkpoints.

■Too much reliance on packet ﬁlters can cause too little reliance on other security methods. Filter sets are not a substitute for password protection, effective safeguarding of passwords, caller ID, the “must match” option in the answer proﬁle, PAP or CHAP in connection proﬁles, callback, and general awareness of how your network may be vulnerable.

An approach to using ﬁlters

The ultimate goal of network security is to prevent unauthorized access to the network without compromising authorized access. Using ﬁlter sets is part of reaching that goal.

Each ﬁlter set you design will be based on one of the following approaches:

■That which is not expressly prohibited is permitted.

■That which is not expressly permitted is prohibited.

It is strongly recommended that you take the latter, and safer, approach to all of your ﬁlter set designs.

Working with IP ﬁlters and ﬁlter sets

This section covers IP ﬁlters and ﬁlter sets. For working with IPX ﬁlters and ﬁlter sets, see “IPX ﬁlters” on page 15-22.

Main

Menu

System

Configuration

Filter Sets

IP Filter Sets

To work with ﬁlters and ﬁlter sets, begin by accessing the ﬁlter set screens.

Note: Make sure you understand how ﬁlters work before attempting to use them. Read the section “About ﬁlters and ﬁlter sets,” beginning on page 15-4.

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Netopia R3100 manual Working with IP ﬁlters and ﬁlter sets, Disadvantages of ﬁlters, An approach to using ﬁlters

Contents

Netopia R3100 Isdn Routers Part Number Contents Ii User’s Reference Guide Part II Advanced Configuration Iv User’s Reference Guide Aurp Vi User’s Reference Guide Part III Appendixes Viii User’s Reference Guide Contents User’s Reference Guide Conﬁguration options for your Netopia R3100 Isdn Router Small Ofﬁce connection to the Internet Small Ofﬁce connection to the Internet Direct Connection to a Corporate Ofﬁce Telecommuter Conﬁgured to accept incoming dial-up connections Conﬁgured for Idsl Part I Getting Started User’s Reference Guide Overview Features and capabilitiesChapter Introduction Introduction How to use this guide What you need Chapter Making the Physical ConnectionsFind a location Making the Physical Connections Identify the connectors and attach the cables Netopia R3100 Isdn Router Back Panel Ports Cable to your router on Services on Netopia R3100 Isdn Router Status Lights Netopia R3100 LED front panel Chapter Setting up your Router with the SmartStart Wizard Setting up your Router with the SmartStart Wizard Before running SmartStart Setting up your Router with the SmartStart Wizard SmartStart Wizard conﬁguration screens Easy or Advanced setup Easy option Setting up your Router with the SmartStart Wizard User’s Reference Guide Setting up your Router with the SmartStart Wizard User’s Reference Guide Advanced option Connection Proﬁle screen on Dynamic conﬁguration recommended Conﬁguration tab Static conﬁguration optional Add. Repeat this process for the secondary DNS Conﬁguring TCP/IP on Macintosh computers TCP/IP TCP/IP or MacTCP Dynamic conﬁguration using MacIP optional Setting up your Router with the SmartStart Wizard User’s Reference Guide Chapter Connecting Your Local Area Network Connecting Your Local Area Network Readying computers on your local network Connecting to an Ethernet network 10Base-T 10BASE-T Remote console Connecting to a LocalTalk network Wiring guidelines for PhoneNET cabling User’s Reference Guide SmartView overview Chapter SmartViewSmartView Navigating SmartView General Machine information Connection Proﬁles Event history pages Device Event History WAN Event History Standard Html web-based monitoring pages User’s Reference Guide About Console-based Management Chapter Console-based ManagementConsole-based Management Connecting through a Telnet session Connecting a local terminal console cable to your router Conﬁguring Telnet software PC ANSI-BBS Navigating through the console screens User’s Reference Guide How to access the Easy Setup console screens Chapter Easy SetupEasy Setup console screens Easy Setup See Appendix A, Troubleshooting, for more suggestions Beginning Easy Setup Isdn Easy Setup PPP Cancel Idsl Easy Setup Easy Setup Proﬁle Previous Screen User’s Reference Guide IP Easy Setup Previous Screen Next Screen Easy Setup Security Conﬁguring Frame Relay Easy Setup Frame Relay screens Isdn Setup Isdn Line Configuration WAN Conﬁguration Frame Relay screens Frame Relay conﬁguration Easy Setup Frame Relay Dlci conﬁguration Displaying a Frame Relay Dlci conﬁguration table Changing a Frame Relay Dlci conﬁguration ADD Dlci NOW Cancel Adding a Frame Relay Dlci conﬁguration Deleting a Frame Relay Dlci conﬁguration Part II Advanced Configuration User’s Reference Guide Creating a new Connection Proﬁle Chapter WAN and System ConfigurationWAN and System Conﬁguration Add Connection Proﬁle screen appears IPX Profile Parameters Remote IPX Network BAP Telco Options Initiate Data Service 64 kb/sec Dial Default Proﬁle How the default proﬁle works Customizing the Default Proﬁle Configuration Default Profile IP parameters default proﬁle screen WAN and System Conﬁguration IPX parameters default proﬁle screen Auxiliary Port Conﬁguration System Conﬁguration screens System Conﬁguration features PAP IP Address Serving Network Protocols SetupFilter Sets Firewalls Date and Time MM/DD/YY Snmp Simple Network Management Protocol Upgrade Feature SetConsole Conﬁguration Security Telephone setup Logging Nov Using SmartPhone for Telephone Services Chapter Using SmartPhone for Telephone ServicesSpecifying telephone connections Inbound Directory Number Using SmartPhone for Telephone Services Deﬁning priority ringing Preview Ring Advanced calling features Line provisioning Conﬁguring supplementary services Cost control feature -- call accounting Chapter Call Accounting and Default Answer ProfileCall Accounting and Default Answer Proﬁle Viewing call accounting statistics Call Accounting Statistics screen appears Scheduled connections Viewing scheduled connections Adding a scheduled connection Set Weekly Schedule Set Once-Only Schedule Modifying a scheduled connection Default Answer ProﬁleHow the Default Answer Proﬁle works Deleting a scheduled connection Customizing the default proﬁle Call Accounting and Default Answer Proﬁle Call acceptance scenarios Network Address Translation features Chapter IP Setup and Network Address TranslationIP Setup and Network Address Translation HOW NAT Works Using Network Address Translation ISP Associating port numbers to nodes Using multiple Connection ProﬁlesNetwork Address Translation guidelines IP setup IP Setup and Network Address Translation Select Add Export. The Add Exported Service screen appears IP Setup IP subnets IP Setup and Network Address Translation Static routes Viewing static routes Adding a static route Modifying a static route Rules of static route installationDeleting a static route Main System IP Address Menu Configuration Serving 163.176.56.90 Dhcp NetBIOS Options MacIP Kip Forwarding Options You have ﬁnished your IP Setup IPX Setup Chapter IPX SetupIPX Features IPX Deﬁnitions Socket Service Advertising Protocol SAPIPX address Routing Information Protocol RIP IPX setup NetBIOSIPX Spooﬁng Default Gateway Address IPX routing tables User’s Reference Guide Installing AppleTalk Chapter AppleTalk SetupAppleTalk Setup AppleTalk networks AppleTalk protocol AppleTalk Setup MacIP Aurp Routers and seeding Conﬁguring AppleTalk EtherTalk Setup LocalTalk Setup Viewing Aurp partners Aurp setupAurp Free Trade Zone Adding an Aurp partner Modifying an Aurp partner Receiving Aurp connections Deleting an Aurp partnerConﬁguring Aurp Options User’s Reference Guide Quick View status overview Chapter Monitoring ToolsMonitoring Tools General status Current status Status lights Statistics & Logs General Statistics Physical Interface Event historiesNetwork Interface WAN Event History Request from our DN Routing tables Device Event History IP routing table IPX Sap Bindery table IPX routing tableAppleTalk routing table Served IP Addresses IP Address Lease Management screen appears System Information Snmp Snmp Setup screen Community strings Snmp traps Modifying IP trap receivers Setting the IP trap receiversViewing IP trap receivers Deleting IP trap receivers User’s Reference Guide Suggested security measures Chapter SecuritySecurity Protecting the Security Options screen User accountsProtecting the conﬁguration screens Dial-in Console Access About ﬁlters and ﬁlter sets Enable SmartStart/SmartView/Web ServerTelnet access What’s a ﬁlter and what’s a ﬁlter set? How ﬁlter sets work Filter priority Packet First filter Match? Yes ﬁltering rule How individual ﬁlters workﬁlter’s actions Parts of a ﬁlter Port numbers Port number comparisons Other ﬁlter attributes Putting the parts together UDP Filtering example #1 Design guidelines Filtering example #2 Working with IP ﬁlters and ﬁlter sets An approach to using ﬁltersDisadvantages of ﬁlters Adding a ﬁlter set Naming a new ﬁlter set Input and output ﬁlters-source and destination Netopia R-series Router Adding ﬁlters to a ﬁlter set ADD this Filter NOW Cancel Modifying ﬁlters Viewing ﬁlter setsViewing ﬁlters Deleting ﬁlters Deleting a ﬁlter set Modifying ﬁlter setsSample IP ﬁlter set TCP Icmp UDP Possible modiﬁcations Security IPX ﬁlters Viewing and modifying packet ﬁlters IPX packet ﬁltersAdding a packet ﬁlter Viewing and modifying packet ﬁlter sets IPX packet ﬁlter setsDeleting a packet ﬁlter Adding a packet ﬁlter set ADD Filter SET NOW Cancel Deleting a packet ﬁlter set IPX SAP ﬁltersViewing and modifying SAP ﬁlters Adding a SAP ﬁlter Viewing and modifying SAP ﬁlter sets IPX SAP ﬁlter setsDeleting a SAP ﬁlter Adding a SAP ﬁlter set Deleting a SAP ﬁlter set Basic IP Packet Components Firewall tutorial General Firewall TermsBasic Protocol Types Example TCP/UDP Ports Firewall design rulesFirewall Logic Logical ANDing Binary RepresentationImplied Rules Established Connections Filter BasicsExample IP Filter Set Screen Example Network Example FiltersExample Example Example Key Security Authentication Features of the Netopia R3100 Token Security AuthenticationUsing the SecurID token card Securing network environments Security authentication components Conﬁguring for security authentication Connecting using security authentication Establishing a dial-on-demand DOD connection call Current Connection Status Establishing a manual connection call User’s Reference Guide Chapter Utilities and Diagnostics Utilities and Diagnostics Ping Start Ping Utilities and Diagnostics Telnet client Stop Ping Trace Route Telnet client screen appears Secure Authentication Monitor Disconnect Telnet Console Session Factory defaultsTransferring conﬁguration and ﬁrmware ﬁles with Tftp Updating ﬁrmware Downloading conﬁguration ﬁles Uploading conﬁguration ﬁles Transferring conﬁguration and ﬁrmware ﬁles with Xmodem Do you want to send a saved configuration to your Netopia? Restarting the system Isdn Switch Loopback Test User’s Reference Guide If the loopback test fails Part III Appendixes User’s Reference Guide Conﬁguration problems Appendix a TroubleshootingTroubleshooting A-1 Console connection problems SmartStart TroubleshootingNetwork problems Technical support Power outagesHow to get support Before contacting Netopia Online product information FAX-Back Obtaining an Isdn line Appendix B Setting Up Telco ServicesFinding an Isdn service provider Choosing an Isdn line Physical Isdn line Setup tipsIsdn Ordering Codes Directory and Spid numbers U models only Switch protocol typeOutside North America only Circuit ID number U models only Testing the Isdn line Long-distance Isdn calls North American models only Completing the Isdn worksheet Isdn Telco Worksheet for North America Isdn Telco Worksheet for Outside North America User’s Reference Guide Appendix C North American Telco Provisioning for Isdn North American Telco Provisioning for Isdn User’s Reference Guide Setting Up Internet Services D-1 Appendix D Setting Up Internet ServicesFinding an Internet service provider Unique requirements ISP’s Point of presence Setting up a Netopia R3100 accountPricing and support Endorsements Deciding on an ISP account With Network Address Translation Obtaining information from the ISPLocal LAN IP address information to obtain Remote WAN IP address information to obtain Remote WAN IP address information to obtain About IP addressing What is IP?Appendix E Understanding IP Addressing Understanding IP Addressing E-1 Subnets and subnet masks Understanding IP Addressing E-3 Example Using subnets on a Class C IP internetSubnet masks Network conﬁguration ISP Network Understanding IP Addressing E-5 Example Working with a Class C subnetDistributing IP addresses Background Technical note on subnet masking Understanding IP Addressing E-7 Netopia R3100 Dhcp Server CharacteristicsConﬁguration Dhcp Address Serving Tips and rules for distributing IP addresses Using address servingManually distributing IP addresses MacIP Serving Understanding IP Addressing E-9 Dhcp example Nested IP subnets Internet Understanding IP Addressing E-11 Broadcasts Packet header types Background Appendix F Understanding Netopia NAT BehaviorNetwork Conﬁguration Understanding Netopia NAT Behavior F-1 User’s Reference Guide Router Netopia Understanding Netopia NAT Behavior F-3 Router Netopia Exported services Understanding Netopia NAT Behavior F-5 Important notes Understanding Netopia NAT Behavior F-7 Summary Virtual Circuits Appendix G Understanding Frame RelayUnderstanding Frame Relay G-1 Committed Burst Size Bc Committed Information Rate CIRExcess Burst Size Be Local Management Interface LMI AddressingLocal and Global DLCIs Understanding Frame Relay G-3 Network Protocol Addressing and Virtual Interfaces Encapsulation and FragmentationFrame Relay partial mesh support Understanding Frame Relay G-5 User’s Reference Guide Isdn events Appendix H Event HistoriesLeased line events Event Histories Isdn event cause codes Event Histories User’s Reference Guide Event Histories User’s Reference Guide About SPIDs Appendix Isdn Conﬁguration GuideDeﬁnitions Isdn Conﬁguration Guide Example SPIDs Dynamic B-channel usage Other incoming call restrictions User’s Reference Guide Appendix J Binary Conversion Table Binary Conversion Table J-1 Decimal Binary Appendix K Further Reading Further Reading K-1 User’s Reference Guide Further Reading K-3 User’s Reference Guide Technical Speciﬁcations and Safety Information L-1 Appendix L Technical Specifications and Safety InformationPinouts for Auxiliary Port Modem Cable DSR Description Power requirementsTechnical Speciﬁcations and Safety Information L-3 Environment North America Agency approvalsRegulatory notices International Technical Speciﬁcations and Safety Information L-5 Australian Safety Information Important safety instructionsDeclaration for Canadian users Telecommunication installation cautions Technical Speciﬁcations and Safety Information L-7Battery User’s Reference Guide Glossary Glossary User’s Reference Guide Glossary User’s Reference Guide Glossary Remapping See network number remapping Glossary User’s Reference Guide Index Index-1 Index-2 Index-3 ISP Index-4 NAT Index-5 Spid Index-6 Limited Warranty and Limitation of Remedies Limited Warranty and Limitation of Remedies User’s Reference Guide