Manuals / Netopia / Computer Equipment / Network Router

Netopia R3100 Appendix F Understanding Netopia NAT Behavior, Network Conﬁguration, Background

Models: R3100

1 320

Download 320 pages 53.76 Kb

Page 267

Understanding Netopia NAT Behavior F-1

Appendix F

Understanding Netopia NAT Behavior

This appendix describes how Network Address Translation works within the Netopia R3100. The Netopia R3100 implements a powerful feature called Network Address Translation (NAT) as speciﬁed in RFC 1631. NAT is used for IP address conservation and for security purposes since there will only be a single IP “presence” on the WAN. This appendix describes the NAT functionality within the Netopia R3100 and provides examples for setup and use.

Network Conﬁguration

Below is a diagram of the network referenced in this appendix.

	ISP Network	Customer Site
	IP: 200.1.1.1	Netopia Router	Netopia Router
	IP: 200.1.1.1	WAN IP: 200.1.1.40	LAN IP: 192.168.5.1
	Mask: 255.255.255.0	WAN IP: 200.1.1.40	LAN IP: 192.168.5.1
	Mask: 255.255.255.0	Mask: 255.255.255.0	Mask: 255.255.255.240
		Mask: 255.255.255.0	Mask: 255.255.255.240
	Router	MAC: 00-00-c5-60-21-0a	MAC: 00-00-c5-60-21-0a
	Router
		Netopia
		Workstation A
		IP: 192.168.5.2	LAN
	Internet	Mask: 255.255.255.240	LAN
	Internet	MAC: 00-05-02-04-12-4f
	WWW Server	Workstation B
	IP: 163.176.4.32	IP: 192.168.5.3
	Mask: 255.255.255.0	Mask: 255.255.255.240
	MAC: 00-05-02-0c-1b-41	MAC: 00-05-02-00-1e-03

Background

NAT is a mechanism employed within the Netopia R3100 to acquire a statically or dynamically assigned IP address on its WAN interface and proxy against locally assigned IP addresses on its LAN interface. The Netopia R3100 uses a one-to-many IP address mapping scheme, that is against a single IP address the Netopia R3100 acquires on its WAN interface the Netopia R3100 can proxy 14, 30, or an unlimited number of IP hosts on the LAN interface.

In order to fully understand how NAT works you must understand how a PPP connection is established and IP addresses are negotiated.

Image 267

Netopia R3100 manual Appendix F Understanding Netopia NAT Behavior, Network Conﬁguration, Background

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 Introduction Features and capabilitiesChapter Introduction OverviewHow to use this guide Making the Physical Connections Chapter Making the Physical ConnectionsFind a location What you needIdentify the connectors and attach the cables Netopia R3100 Isdn Router Back Panel Ports Cable to your router on Services on Netopia R3100 LED front panel Netopia R3100 Isdn Router Status LightsSetting up your Router with the SmartStart Wizard Chapter Setting up your Router with the SmartStart WizardBefore running SmartStart SmartStart Wizard conﬁguration screens Setting up your Router with the SmartStart WizardEasy option Easy or Advanced setupSetting 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 Conﬁguration tab Dynamic conﬁguration recommendedStatic conﬁguration optional Add. Repeat this process for the secondary DNS TCP/IP Conﬁguring TCP/IP on Macintosh computersTCP/IP or MacTCP Dynamic conﬁguration using MacIP optional Setting up your Router with the SmartStart Wizard User’s Reference Guide Connecting Your Local Area Network Chapter Connecting Your Local Area NetworkReadying computers on your local network 10Base-T Connecting to an Ethernet network10BASE-T Remote console Connecting to a LocalTalk network Wiring guidelines for PhoneNET cabling User’s Reference Guide Chapter SmartView SmartView overviewSmartView General Machine information Navigating SmartViewEvent history pages Connection ProﬁlesDevice Event History WAN Event History Standard Html web-based monitoring pages User’s Reference Guide Chapter Console-based Management About Console-based ManagementConsole-based Management Connecting through a Telnet session Conﬁguring Telnet software Connecting a local terminal console cable to your routerPC ANSI-BBS Navigating through the console screens User’s Reference Guide Easy Setup Chapter Easy SetupEasy Setup console screens How to access the Easy Setup console screensSee Appendix A, Troubleshooting, for more suggestions Isdn Easy Setup Beginning Easy SetupPPP Cancel Idsl Easy Setup Previous Screen Easy Setup ProﬁleUser’s Reference Guide Previous Screen Next Screen IP Easy SetupEasy Setup Security Conﬁguring Frame Relay Isdn Easy Setup Frame Relay screensWAN Conﬁguration Frame Relay screens Setup Isdn Line ConfigurationFrame Relay conﬁguration Easy Setup Frame Relay Dlci conﬁguration Displaying a Frame Relay Dlci conﬁguration table Changing a Frame Relay Dlci conﬁguration Adding a Frame Relay Dlci conﬁguration ADD Dlci NOW CancelDeleting a Frame Relay Dlci conﬁguration Part II Advanced Configuration User’s Reference Guide Chapter WAN and System Configuration Creating a new Connection ProﬁleWAN 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 Configuration Default Profile Customizing the Default ProﬁleIP parameters default proﬁle screen WAN and System Conﬁguration Auxiliary Port Conﬁguration IPX parameters default proﬁle screenSystem Conﬁguration screens System Conﬁguration features PAP Date and Time Network Protocols SetupFilter Sets Firewalls IP Address ServingMM/DD/YY Security Upgrade Feature SetConsole Conﬁguration Snmp Simple Network Management ProtocolLogging Telephone setupNov Chapter Using SmartPhone for Telephone Services Using SmartPhone for Telephone ServicesSpecifying telephone connections Inbound Directory Number Using SmartPhone for Telephone Services Preview Ring Deﬁning priority ringingLine provisioning Advanced calling featuresConﬁguring supplementary services Chapter Call Accounting and Default Answer Profile Cost control feature -- call accountingCall 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 Deleting a scheduled connection Default Answer ProﬁleHow the Default Answer Proﬁle works Modifying a scheduled connectionCustomizing the default proﬁle Call Accounting and Default Answer Proﬁle Call acceptance scenarios Chapter IP Setup and Network Address Translation Network Address Translation featuresIP Setup and Network Address Translation HOW NAT Works Using Network Address Translation ISP Using multiple Connection Proﬁles Associating port numbers to nodesNetwork 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 Rules of static route installation Modifying a static routeDeleting 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 Deﬁnitions Chapter IPX SetupIPX Features IPX SetupRouting Information Protocol RIP Service Advertising Protocol SAPIPX address SocketNetBIOS IPX setupIPX Spooﬁng Default Gateway Address IPX routing tables User’s Reference Guide Chapter AppleTalk Setup Installing AppleTalkAppleTalk Setup AppleTalk protocol AppleTalk networksAppleTalk Setup Aurp MacIPRouters and seeding Conﬁguring AppleTalk EtherTalk Setup LocalTalk Setup Aurp setup Viewing Aurp partnersAurp Free Trade Zone Modifying an Aurp partner Adding an Aurp partnerDeleting an Aurp partner Receiving Aurp connectionsConﬁguring Aurp Options User’s Reference Guide Chapter Monitoring Tools Quick View status overviewMonitoring Tools General status Status lights Current statusGeneral Statistics Statistics & LogsEvent histories Physical InterfaceNetwork Interface Request from our DN WAN Event HistoryDevice Event History Routing tablesIP routing table IPX routing table IPX Sap Bindery tableAppleTalk routing table Served IP Addresses IP Address Lease Management screen appears Snmp System InformationCommunity strings Snmp Setup screenSnmp traps Deleting IP trap receivers Setting the IP trap receiversViewing IP trap receivers Modifying IP trap receiversUser’s Reference Guide Chapter Security Suggested security measuresSecurity User accounts Protecting the Security Options screenProtecting the conﬁguration screens Dial-in Console Access What’s a ﬁlter and what’s a ﬁlter set? Enable SmartStart/SmartView/Web ServerTelnet access About ﬁlters and ﬁlter setsFilter priority How ﬁlter sets workPacket First filter Match? Yes Parts of a ﬁlter How individual ﬁlters workﬁlter’s actions ﬁltering rulePort number comparisons Port numbersPutting the parts together Other ﬁlter attributesFiltering example #1 UDPFiltering example #2 Design guidelinesAn approach to using ﬁlters Working with IP ﬁlters and ﬁlter setsDisadvantages of ﬁlters Adding a ﬁlter set Input and output ﬁlters-source and destination Naming a new ﬁlter setAdding ﬁlters to a ﬁlter set Netopia R-series RouterADD this Filter NOW Cancel Deleting ﬁlters Viewing ﬁlter setsViewing ﬁlters Modifying ﬁltersModifying ﬁlter sets Deleting a ﬁlter setSample IP ﬁlter set TCP Icmp UDP Possible modiﬁcations Security IPX ﬁlters IPX packet ﬁlters Viewing and modifying packet ﬁltersAdding a packet ﬁlter Adding a packet ﬁlter set IPX packet ﬁlter setsDeleting a packet ﬁlter Viewing and modifying packet ﬁlter setsADD Filter SET NOW Cancel IPX SAP ﬁlters Deleting a packet ﬁlter setViewing and modifying SAP ﬁlters Adding a SAP ﬁlter Adding a SAP ﬁlter set IPX SAP ﬁlter setsDeleting a SAP ﬁlter Viewing and modifying SAP ﬁlter setsDeleting a SAP ﬁlter set Firewall tutorial General Firewall Terms Basic IP Packet ComponentsBasic Protocol Types Firewall design rules Example TCP/UDP PortsFirewall Logic Binary Representation Logical ANDingImplied Rules Filter Basics Established ConnectionsExample IP Filter Set Screen Example Filters Example NetworkExample Example Example Securing network environments Token Security AuthenticationUsing the SecurID token card Key Security Authentication Features of the Netopia R3100Conﬁguring for security authentication Security authentication componentsEstablishing a dial-on-demand DOD connection call Connecting using security authenticationCurrent Connection Status Establishing a manual connection call User’s Reference Guide Utilities and Diagnostics Chapter Utilities and DiagnosticsStart Ping PingUtilities and Diagnostics Stop Ping Telnet clientTelnet client screen appears Trace RouteSecure Authentication Monitor Factory defaults Disconnect Telnet Console SessionTransferring conﬁguration and ﬁrmware ﬁles with Tftp Updating ﬁrmware Uploading conﬁguration ﬁles Downloading conﬁguration ﬁlesTransferring 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 Appendix a Troubleshooting Conﬁguration problemsTroubleshooting A-1 SmartStart Troubleshooting Console connection problemsNetwork problems Before contacting Netopia Power outagesHow to get support Technical supportFAX-Back Online product informationChoosing an Isdn line Appendix B Setting Up Telco ServicesFinding an Isdn service provider Obtaining an Isdn lineSetup tips Physical Isdn lineIsdn Ordering Codes Circuit ID number U models only Switch protocol typeOutside North America only Directory and Spid numbers U models onlyLong-distance Isdn calls North American models only Testing the Isdn lineCompleting the Isdn worksheet Isdn Telco Worksheet for North America Isdn Telco Worksheet for Outside North America User’s Reference Guide North American Telco Provisioning for Isdn Appendix C North American Telco Provisioning for IsdnUser’s Reference Guide Unique requirements Appendix D Setting Up Internet ServicesFinding an Internet service provider Setting Up Internet Services D-1Endorsements Deciding on an ISP account Setting up a Netopia R3100 accountPricing and support ISP’s Point of presenceRemote WAN IP address information to obtain Obtaining information from the ISPLocal LAN IP address information to obtain With Network Address TranslationRemote WAN IP address information to obtain Understanding IP Addressing E-1 What is IP?Appendix E Understanding IP Addressing About IP addressingSubnets and subnet masks Example Using subnets on a Class C IP internet Understanding IP Addressing E-3Subnet masks ISP Network Network conﬁgurationBackground Example Working with a Class C subnetDistributing IP addresses Understanding IP Addressing E-5Technical note on subnet masking Dhcp Address Serving Netopia R3100 Dhcp Server CharacteristicsConﬁguration Understanding IP Addressing E-7MacIP Serving Using address servingManually distributing IP addresses Tips and rules for distributing IP addressesDhcp example Understanding IP Addressing E-9Internet Nested IP subnetsUnderstanding IP Addressing E-11 Packet header types BroadcastsUnderstanding Netopia NAT Behavior F-1 Appendix F Understanding Netopia NAT BehaviorNetwork Conﬁguration BackgroundUser’s Reference Guide Understanding Netopia NAT Behavior F-3 Router NetopiaRouter Netopia Understanding Netopia NAT Behavior F-5 Exported servicesImportant notes Understanding Netopia NAT Behavior F-7 Summary Appendix G Understanding Frame Relay Virtual CircuitsUnderstanding Frame Relay G-1 Committed Information Rate CIR Committed Burst Size BcExcess Burst Size Be Understanding Frame Relay G-3 AddressingLocal and Global DLCIs Local Management Interface LMIEncapsulation and Fragmentation Network Protocol Addressing and Virtual InterfacesFrame Relay partial mesh support Understanding Frame Relay G-5 User’s Reference Guide Event Histories Appendix H Event HistoriesLeased line events Isdn eventsIsdn event cause codes Event Histories User’s Reference Guide Event Histories User’s Reference Guide Isdn Conﬁguration Guide Appendix Isdn Conﬁguration GuideDeﬁnitions About SPIDsDynamic B-channel usage Example SPIDsOther incoming call restrictions User’s Reference Guide Binary Conversion Table J-1 Appendix J Binary Conversion TableDecimal Binary Further Reading K-1 Appendix K Further ReadingUser’s Reference Guide Further Reading K-3 User’s Reference Guide Appendix L Technical Specifications and Safety Information Technical Speciﬁcations and Safety Information L-1Pinouts for Auxiliary Port Modem Cable DSR Environment Power requirementsTechnical Speciﬁcations and Safety Information L-3 DescriptionInternational Agency approvalsRegulatory notices North AmericaTechnical Speciﬁcations and Safety Information L-5 Important safety instructions Australian Safety InformationDeclaration for Canadian users Technical Speciﬁcations and Safety Information L-7 Telecommunication installation cautionsBattery User’s Reference Guide Glossary GlossaryUser’s Reference Guide Glossary User’s Reference Guide Glossary Remapping See network number remapping Glossary User’s Reference Guide Index-1 IndexIndex-2 ISP Index-3NAT Index-4Spid Index-5Index-6 Limited Warranty and Limitation of Remedies Limited Warranty and Limitation of RemediesUser’s Reference Guide