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Chapter 1: Introduction

What’s in this Guide?

4-Port Gigabit Security Router with VPN

What’s in this Guide?

This user guide covers the steps for setting up and using the 10/100 4-Port VPN Router.

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Chapter 1: Introduction

This chapter describes the 4-Port Gigabit Security Router with VPN applications and this User Guide.

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Chapter 2: Networking Basics

This chapter describes the basics of networking.

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Chapter 3: Planning Your Virtual Private Network (VPN)

This chapter describes a VPN and its various applications.

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Chapter 4: Getting to Know the Router

This chapter describes the physical features of the Router.

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Chapter 5: Connecting the Router

This chapter instructs you on how to connect the Router to your network.

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Chapter 6: Setting Up and Configuring the Router

This chapter explains how to use the Web-based Utility to set up the Router and configure its settings.

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Appendix A: Troubleshooting

This appendix describes some problems and solutions, as well as frequently asked questions, regarding

installation and use of the 4-Port Gigabit Security Router with VPN.

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Appendix B: Using the Linksys QuickVPN Software for Windows 2000 or XP

This appendix instructs you on how to use the Linksys QuickVPN software if you are using a Windows 2000 or

XP PC.

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Appendix C: Configuring IPSec between a Windows 2000 or XP PC and the Router

This appendix instructs you on how to establish a secure IPSec tunnel using pre-shared keys to join a private

network inside the VPN Router and a Windows 2000 or XP PC.

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Appendix D: Configuring a Gateway-to-Gateway IPSec Tunnel

This appendix describes how to configure an IPSec VPN Tunnel between two VPN Routers.

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Appendix E: Finding the MAC Address and IP Address for your Ethernet Adapter.

This appendix describes how to find the MAC address for your computer’s Ethernet adapter so you can use

the MAC filtering and/or MAC address cloning feature of the Router. It also explains how to find the IP address

for your computer.

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Chapter 1: Introduction

What’s in this Guide?

4-Port Gigabit Security Router with VPN

•

Appendix F: Physical Setup of the Router

This appendix describes the physical setup of the Router.

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Appendix G: Windows Help

This appendix describes how you can use Windows Help for instructions about networking, such as installing

the TCP/IP protocol.

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Appendix H Glossary

This appendix gives a brief glossary of terms frequently used in networking.

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Appendix I: Specifications

This appendix provides the technical specifications for the Router.

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Appendix J: Warranty Information

This appendix supplies the warranty information for the Router.

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Appendix K: Regulatory Information

This appendix supplies the regulatory information regarding the Router.

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Appendix L: Contact Information

This appendix provides contact information for a variety of Linksys resources, including Technical Support.

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Chapter 2: Networking Basics

An Introduction to LANs

4-Port Gigabit Security Router with VPN

Chapter 2: Networking Basics

An Introduction to LANs

A Router is a network device that connects two networks together.

The Router connects your local area network (LAN), or the group of PCs in your home or office, to the Internet. The

Router processes and regulates the data that travels between these two networks.

The Router’s Network Address Translation (NAT) technology protects your network of PCs so users on the Internet

cannot “see” your PCs. This is how your LAN remains private. The Router protects your network by inspecting the

first packet coming in through the Internet port before delivery to the final destination on one of the Ethernet

ports. The Router inspects Internet port services like the web server, ftp server, or other Internet applications,

and, if allowed, it will forward the packet to the appropriate PC on the LAN side.

The Use of IP Addresses

IP stands for Internet Protocol. Every device in an IP-based network, including PCs, print servers, and routers,

requires an IP address to identify its location, or address, on the network. This applies to both the Internet and

LAN connections.

There are two ways of assigning IP addresses to your network devices.

A static IP address is a fixed IP address that you assign manually to a PC or other device on the network. Since a

static IP address remains valid until you disable it, static IP addressing ensures that the device assigned it will

always have that same IP address until you change it. Static IP addresses are commonly used with network

devices such as server PCs or print servers.

If you use the Router to share your cable or DSL Internet connection, contact your ISP to find out if they have

assigned a static IP address to your account. If so, you will need that static IP address when configuring the

Router. You can get the information from your ISP.

A dynamic IP address is automatically assigned to a device on the network. These IP addresses are called

dynamic because they are only temporarily assigned to the PC or other device. After a certain time period, they

expire and may change. If a PC logs onto the network (or the Internet) and its dynamic IP address has expired, the

DHCP server will assign it a new dynamic IP address.

Dynamic IP address

: a temporary IP

address assigned by a DHCP server.

Static IP address

: a fixed address

assigned to a computer or device that

is connected to a network.

NAT (Network Address Translation)

:

NAT technology translates IP

addresses of a local area network to a

different IP address for the Internet.

DHCP (Dynamic Host Configuration

Protocol)

: a protocol that lets one

device on a local network, known as a

DHCP server, assign temporary IP

addresses to the other network

devices, typically computers.

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Chapter 2: Networking Basics

The Use of IP Addresses

4-Port Gigabit Security Router with VPN

A DHCP server can either be a designated PC on the network or another network device, such as the Router. By

default, the Router’s Internet Connection Type is

Obtain an IP automatically

(DHCP).

The PC or network device obtaining an IP address is called the DHCP client. DHCP frees you from having to assign

IP addresses manually every time a new user is added to your network.

For DSL users, many ISPs may require you to log on with a user name and password to gain access to the

Internet. This is a dedicated, high-speed connection type called Point to Point Protocol over Ethernet (PPPoE).

PPPoE is similar to a dial-up connection, but PPPoE does not dial a phone number when establishing a

connection. It also will provide the Router with a dynamic IP address to establish a connection to the Internet.

By default, a DHCP server (on the LAN side) is enabled on the Router. If you already have a DHCP server running

on your network, you MUST disable one of the two DHCP servers. If you run more than one DHCP server on your

network, you will experience network errors, such as conflicting IP addresses. To disable DHCP on the Router, see

the Basic Setup section in “Chapter 6: Setting Up and Configuring the Router.”

LAN

: the computers and networking products that

make up your local network

NOTE:

Since the Router is a device that connects two

networks, it needs two IP addresses—one for the LAN,

and one for the Internet. In this User Guide, you’ll see

references to the “Internet IP address” and the “LAN IP

address.”

Since the Router uses NAT technology, the only IP

address that can be seen from the Internet for your

network is the Router’s Internet IP address. However,

even this Internet IP address can be blocked, so that the

Router and network seem invisible to the Internet.

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Chapter 3: Planning Your Virtual Private Network (VPN)

Why do I need a VPN?

4-Port Gigabit Security Router with VPN

Chapter 3: Planning Your Virtual Private Network (VPN)

Why do I need a VPN?

Computer networking provides a flexibility not available when using an archaic, paper-based system. With this

flexibility, however, comes an increased risk in security. This is why firewalls were first introduced. Firewalls help

to protect data inside of a local network. But what do you do once information is sent outside of your local

network, when e-mails are sent to their destination, or when you have to connect to your company's network

when you are out on the road? How is your data protected?

That is when a VPN can help. VPNs are called Virtual Private Networks because they secure data moving outside

of your network as if it were still within that network.

When data is sent out across the Internet from your computer, it is always open to attacks. You may already have

a firewall, which will help protect data moving around or held within your network from being corrupted or

intercepted by entities outside of your network, but once data moves outside of your network—when you send

data to someone via e-mail or communicate with an individual over the Internet—the firewall will no longer

protect that data.

At this point, your data becomes open to hackers using a variety of methods to steal not only the data you are

transmitting but also your network login and security data. Some of the most common methods are as follows:

1) MAC Address Spoofing

Packets transmitted over a network, either your local network or the Internet, are preceded by a packet header.

These packet headers contain both the source and destination information for that packet to transmit efficiently.

A hacker can use this information to spoof (or fake) a MAC address allowed on the network. With this spoofed

MAC address, the hacker can also intercept information meant for another user.

2) Data Sniffing

Data “sniffing” is a method used by hackers to obtain network data as it travels through unsecured networks,

such as the Internet. Tools for just this kind of activity, such as protocol analyzers and network diagnostic tools,

are often built into operating systems and allow the data to be viewed in clear text.

3) Man in the middle attacks

Once the hacker has either sniffed or spoofed enough information, he can now perform a “man in the middle”

attack. This attack is performed, when data is being transmitted from one network to another, by rerouting the

packet

: a unit of data sent over a network

vpn

(virtual private network): a security

measure to protect data as it leaves one

network and goes to another over the Internet

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