Share small office broadband pipes using a Linksys router and Win2K Pro

Looking for a small office routing solution? A Linksys EtherFast router may be just what the doctor ordered. Erik Eckel shows you how to share up to 253 IP addresses by pairing a Linksys router and Win2K Pro.

The Linksys line of EtherFast Cable/DSL Routers can rescue you from small office networking jams. For less than $230, you can deploy one of Linksys’ multifunction network devices quickly and efficiently.

Configuration is fairly straightforward. I’ll show you how to configure small-office or branch-office systems to work with such devices, but first, let’s quickly review the device’s features.

Linksys EtherFast Cable/DSL Router features
If you’re supporting a small office or branch location where you wish to share (or must share) a single broadband Internet connection, Linksys’ cable and DSL routers can do the trick. The device is available in three versions:
  • A single-port version (model number BEFSR11)
  • A four-port version (model number BEFSR41), shown in Figure A
  • An eight-port version (model number BEFSR81)

All three of the devices can be used with a hub. Further, all three versions support up to 253 machines using a single Internet IP address.

Figure A
The Linksys four-port EtherFast Cable/DSL Router device

In addition to providing routing services, the Linksys EtherFast Cable/DSL Routers provide the following advantages:
  • Firewall services, including port security and packet filtering
  • Switching services at 100 Mbps
  • Gateway services, including port forwarding
  • DHCP services, using an internal IP address range (192.168.x.y)

The units require only a small amount of desk or shelf space. The device’s footprint measures 7.31x6.16x1.88 inches.

Other benefits include DMZ hosting (the ability to place a machine outside the firewall), local or remote browser-based administration, SNMP-enabled internal user access filtering, support for WinSock 2.0 and Windows 2000 Smart Applications, and support for PPPoE (Point-to-Point Protocol over Ethernet).
Linksys EtherFast Cable/DSL Router offers another powerful but easy-to-miss benefit. If you wish to use a unique domain or workgroup naming scheme for test purposes or other reasons, you can implement whichever naming scheme you wish. ISP servers are happy with what they see: the MAC address of your cable or DSL modem.
The eight-port hub includes 10 RJ-45 ports. One holds the RJ-45 EtherNet connection to the WAN link. This port supports speeds of up to 10 Mbps. Another port serves as an uplink connection to a hub. It is used to add more systems than the eight physical ports support.

The other eight ports support 10BaseT EtherNet or 100BaseTX Fast EtherNet ports for LAN connections. It’s important to remember that your LAN connections will only be as fast as the cables and network interface cards (NICs) that you use on your network. If you’re using a 10-Mbps NIC in one machine but 100BaseTX cabling and hubs, the data transmission rate will be constrained to 10 Mbps by the NIC.

Before deploying a Linksys router, you’ll want to ensure you can make use of these features. Several items must be in place.

Your first step
The first thing you’ll want to do is ensure you have a data circuit boasting sufficient bandwidth to share. At a minimum, you’d want a DSL or cable connection supporting a couple hundred Kbps. You could go with less if you’re only supporting a few machines. Ultimately, the bandwidth you’ll need is dependent on the applications your users run and their needs for remote resources, e-mail, Internet access, etc.

Next, check all the systems that will be connecting to the EtherFast Cable/DSL Router to ensure they possess functioning NICs. Each system will also need a category 5 drop (you can use category 3, but transmission speeds are slower) connecting it to the EtherFast router.

Secure an IP address
You’ll need to reserve an Internet IP address for the Linksys router. Many ISPs serve up Internet IP addresses on consumer plans using DHCP. You can usually run an IPCONFIG /ALL command from a Windows 2000 (or Windows NT) command prompt, learn your IP address, and then enter it using the Linksys Web interface.

You’ll also need to know a few other IP addresses, which I’ll cover in a moment. If you’re still stuck using a Windows 9x machine, go with WINIPCFG /ALL. It’d probably be best to print them out. Write them down, at the least.
The Linksys cable/DSL routers work with Linux as well as Windows. In fact, don’t be surprised to find a copy of TurboLinux bundled with your router, should you purchase one. Using Linux, you’d want to run the /sbin/ifconfig command to identify your Internet IP address. Alternatively, you can open an X terminal, run linuxconf, and review the system’s network settings using that interface.
If you’re using a cable or DSL service for business, however, you should be subscribing to a business-based plan. In most cases, you’ll then receive a static IP address.

Let’s look at how the router is configured when using a single, static address, since that’s what most small businesses are likely to use. In the event you’re using a DHCP-provided Internet IP address, don’t sweat it. There’s a single check box to be toggled; that’s the only difference vs. configuration with a static IP address.

Linksys EtherFast Cable/DSL Router hardware setup
The router’s setup is surprisingly easy. In case you experience trouble, excellent documentation describing a quick installation is included.

You should start by powering down the systems you wish to support via the router. Next, plug all your systems’ category 5 cables into the router’s RJ-45 ports. If you’re using more than eight (with the eight-port model), you’ll plug the additional systems into a hub you supply and the hub into the uplink port.

After plugging your broadband modem into the router, you’re ready to plug in the power supply for the Linksys unit. Make sure you start fresh by depressing the router’s reset button. You’ll need to keep it depressed for three seconds.

Your hardware setup is now complete. You’re ready to begin the software phase of the setup process. Start by powering up one of the systems you’ve connected to the router. In this case, we’ll use a system running Windows 2000 Professional.

System configuration
After your machine boots, right-click My Network Places and select Properties. This action opens the Network And Dial-up Connections applet. From this applet, select the network connection you wish the router to use. The connection in this example is named Linksys (Internet), as can be seen in Figure B.

Figure B
You must configure each system’s networking settings.

Right-click the connection you wish to use and select Properties. Select Internet Protocol (TCP/IP), as shown in Figure C, and click Properties. From the Internet Protocol (TCP/IP) Properties box, ensure the Obtain An IP Address Automatically radio button is selected. Select OK twice to close both boxes.
The Internet Protocol (TCP/IP) listing may not appear. If that’s the case, you’ll have to install it. You can do so in Windows 2000 by selecting Install, Protocol, and selecting Internet Protocol (TCP/IP) from the menu that will appear.

Figure C
You must specify that an address be obtained automatically. Changing this setting prompts your system to send a network request seeking a DHCP server, which the Linksys router will answer.

Linksys EtherFast Cable/DSL Router configuration
After you reboot your system to trigger the changes, you’re ready to set up and configure the router. Fire up a browser and enter the following address:

The 192.x.y.z IP addresses are not Internet IP addresses. By that, I mean they’re not unique to the World Wide Web. This address range has been preserved for internal, or private, use.

You’ll be greeted with the screen shown in Figure D. It requires that the router’s password be entered.
If you can’t access the Web administration tool, ensure you’ve turned other Internet sharing proxy services off. A proxy server could have already taken the address, which will prevent the Linksys device from responding. You’ll have to wrestle that IP address back for use by the router (at least until you can access it to change the Linksys device’s default internal IP address).
Linksys includes the default value to be entered. I recommend you change it the first time you use the router. I’ll show you how to do that a little later.

Figure D
You must enter a valid user name and password to configure the router.

Enter the values Linksys provides, or provide the new entries you’ve specified, and click OK. The next thing you see should be the Linksys Setup screen, as shown in Figure E. (While I trust the router’s firewall, I don’t want to encourage hacking it, hence the blocked-out addresses.) If not, double-check to ensure your system’s DHCP service hasn’t been stopped.

Figure E
The administration software is Web-based.

Enter the name you’d like to use for your router in the Router Name box. Enter the domain name you’d like to use. You may not need to provide any values at all. Check with your ISP if you’re not sure.

Unless an internal naming scheme already in place interferes, you can leave the LAN IP Address entered as is. It should read

Remember I mentioned earlier that it’s easy to set the router itself to request an IP address? All you need to do is select the Obtain IP Address Automatically radio button under WAN Address.

Most likely, you’ll want to enter a static IP address. Select Specify An IP Address instead. Next, enter the IP address you wish to use or that you’ve been assigned by your ISP. This is not, of course, the IP address for your system but the IP address of the router that you’re now configuring.

Next, you need to specify the subnet mask, default gateway, and your ISP’s DNS servers. These values would have been provided when you executed the IPCONFIG /ALL command on the Windows 2000 Professional machine earlier.

If you’re using PPPoE, you can enable it. Just be sure to also provide the required user name and password. Click Apply.

The next thing you need to do is select the DHCP tab within the Web-based software configuration tool. Select the Enable radio button and specify the first internal IP address the DHCP service should start with when receiving a request. Don’t forget to specify the total number of DHCP addresses the router should provide.

Click Apply, and you’re finished with the basic setup.

Change the default password
As I mentioned earlier, you should also change the default password. Linksys includes the password you must enter the first time you access the Web-based administration tool. After that, you’re on your own.

Don’t think there aren’t freaks searching for these routers and trying the default security account settings in an attempt to get in. Don’t make their day. Change the password setting the first time you use the router.

The password setting is easily changed. Click the Password tab on the Linksys router’s Web administration tool. It’ll reveal the screen you see in Figure F.

Figure F
Use the Password tab to access the security account settings.

Enter the password you wish to use. Re-enter it and then click Apply. I recommend you specify an alphanumeric password that’s not related to any of the following:
  • Your birth date
  • Your address
  • Your anniversary
  • Kid names
  • Pet names

Hackers try those first. Instead, choose something others wouldn’t be able to easily guess.

Check your configuration
Once you’ve specified the configuration you’d like your router to use, check it. Select the Status tab. It’ll display the following:
  • Router name
  • LAN MAC address
  • LAN IP address
  • LAN subnet mask
  • LAN DHCP server status
  • WAN MAC address
  • WAN MAC address
  • WAN IP address
  • WAN subnet mask
  • WAN DNS servers
  • Firmware version
  • PPPoE status

The Status tab also provides access to a DHCP table, should you wish to review it. Selecting the provided DHCP Clients Table button prompts a pop-up screen to appear. It lists all the systems that have received an internal IP address from the router and displays the systems’ host names and MAC addresses. The table also lists the DHCP address each machine is using.

Have at it
Once you’ve specified the settings you wish to use on the router and configured all your clients, you’re good to go. Your systems, when booted, will send a DHCP request to the router. The router, in turn, will provide DHCP addresses to the systems.

Then, knowing the address of the router, the systems will be able to contact DNS servers. These DNS servers will fulfill name translation services, so the systems behind the router will be able to access the Internet using their internal IP addresses.

They won’t even know the router’s there. Hackers will be able to see the router but not the systems behind it. Isn’t that the way it’s all supposed to work?
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