HOW NAT Works | Netopia R3100 instruction

11-2 User’s Reference Guide

Network Address Translation works by remapping the source IP address of trafﬁc from the LAN to a single static or dynamically assigned IP address shown to the remote side of the router.

HOW NAT WORKS

With NAT

192.168.1.100

ISP* 192.168.1.102 192.168.1.103

163.167.132.1

192.168.1.104

192.168.1.105

192.168.1.106

	Without NAT
		163.167.132.1
	163.167.132.1	163.167.132.2
	163.167.132.1	163.167.132.3
	163.167.132.2	163.167.132.3
	163.167.132.2
	163.167.132.3
	163.167.132.4
	163.167.132.5	163.167.132.4
	163.167.132.6	163.167.132.4
	163.167.132.6
		163.167.132.5
		163.167.132.6
		*or corporate intranet router

The feature can be implemented on a per Connection Proﬁle basis. The network router can use two or more Connection Proﬁles simultaneously to connect to two or more networks. Each proﬁle may have Network Address Translation enabled.

When Network Address Translation is enabled, the Netopia R3100 can either use a statically assigned IP address, or one dynamically assigned each time the router connects to the ISP. While a dynamically assigned IP address offers the ISP more ﬂexibility, it does have an important limitation. The router will require a static IP address to support Web, FTP, or other services available to the WAN. To support these services with Network Address Translation enabled, a service can only be associated with one machine on the LAN.

When connected to the Internet or some other large network using Network Address Translation, the individual machines on your LAN are not directly accessible from the WAN. Network Address Translation provides an inherently secure method of connection to the outside world.

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Netopia R3100 manual HOW NAT Works

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 Chapter SmartView SmartView overviewSmartView 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 Chapter Console-based Management About 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 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 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 Chapter Using SmartPhone for Telephone Services 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 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 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 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 Setup Chapter IPX SetupIPX Features IPX Deﬁnitions Socket Service Advertising Protocol SAPIPX address Routing Information Protocol RIP NetBIOS IPX setupIPX Spooﬁng Default Gateway Address IPX routing tables User’s Reference Guide Chapter AppleTalk Setup Installing AppleTalkAppleTalk Setup AppleTalk networks AppleTalk protocol AppleTalk Setup MacIP Aurp Routers and seeding Conﬁguring AppleTalk EtherTalk Setup LocalTalk Setup Aurp setup Viewing Aurp partnersAurp Free Trade Zone Adding an Aurp partner Modifying an Aurp partner Deleting an Aurp partner Receiving Aurp connectionsConﬁguring Aurp Options User’s Reference Guide Chapter Monitoring Tools Quick View status overviewMonitoring Tools General status Current status Status lights Statistics & Logs General Statistics Event histories Physical InterfaceNetwork Interface WAN Event History Request from our DN Routing tables Device Event History IP routing table IPX routing table IPX Sap Bindery 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 Chapter Security Suggested security measuresSecurity User accounts Protecting the Security Options screenProtecting 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 An approach to using ﬁlters Working with IP ﬁlters and ﬁlter setsDisadvantages 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 Modifying 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 Viewing and modifying packet ﬁlter sets IPX packet ﬁlter setsDeleting a packet ﬁlter Adding a packet ﬁlter set ADD Filter SET NOW Cancel IPX SAP ﬁlters Deleting a packet ﬁlter setViewing 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 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 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 Factory defaults Disconnect Telnet Console SessionTransferring 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 Appendix a Troubleshooting Conﬁguration problemsTroubleshooting A-1 SmartStart Troubleshooting Console connection problemsNetwork 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 Setup tips Physical Isdn lineIsdn 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 Example Using subnets on a Class C IP internet Understanding IP Addressing E-3Subnet 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 Appendix G Understanding Frame Relay Virtual CircuitsUnderstanding Frame Relay G-1 Committed Information Rate CIR Committed Burst Size BcExcess Burst Size Be Local Management Interface LMI AddressingLocal and Global DLCIs Understanding Frame Relay G-3 Encapsulation and Fragmentation Network Protocol Addressing and Virtual InterfacesFrame 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 Appendix L Technical Specifications and Safety Information Technical Speciﬁcations and Safety Information L-1Pinouts 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 Important safety instructions Australian Safety InformationDeclaration for Canadian users Technical Speciﬁcations and Safety Information L-7 Telecommunication installation cautionsBattery 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