Figure 1 Back panel of Linksys router
Revised: January 19, 2007
By Richard G. Baldwin
File: FwlProj010.htm
This laboratory project was prepared specifically for the benefit of my students who are enrolled in ITNW 1351, Fundamentals of Wireless LANs.
The project was designed under the assumption that students enrolled in the course have successfully completed the prerequisite course, ITNW 1325, Fundamentals of Networking Technologies.
The project design also assumes that the students are actively studying the material in the prescribed textbook for this course, which explains such complex topics as the IEEE 802.11g wireless specifications.
Another browser window
I recommend that you open another copy of this document in a separate browser window so that you can easily view the discussion and the figures at the same time.
The purpose of this laboratory project is to demonstrate the inherent connectivity and security (or lack thereof) of a Linksys WRT54G Wireless-G Broadband Router right out of the box using factory settings.
The following equipment is required to complete this laboratory project:
Crossover cable versus regular cable
RJ-45 patch cables come in at least two varieties, regular and crossover. You need to make certain that you have a regular patch cable and not a crossover cable.
How can you tell the difference?
If the cable has transparent connectors on each end, you can tell the difference by inspection of the color and the order of the wires inside the connector.
Hold one connector in each hand with the plastic spring widgets down and the ends of the connectors facing away from you.
Observe the left-to-right order of the colors of the wires in each connector. If the cable is a regular patch cable, the order of the colors of the wires will be the same in each connector.
If the cable is a crossover cable, the order of the colors of the wires in one connector will be different from the order of the colors in the other connector.
Wireless NIC configuration
Wireless NICs come in a variety of configurations. Many of the desktop computers in the ACC Northridge network lab are equipped with a Linksys Wireless-G PCI adapter, which is advertised as being compatible with both IEEE 802.11b and IEEE 802.11g specifications.
Plug-in cards
My personal laptop computer uses a Belkin Model F5D7010 54g 802.11g Wireless Notebook Network Card, which can be plugged into a slot on the side of the computer.
USB configuration
Wireless NICs are also available in packages that plug into the USB ports of both desktop and laptop computers.
Wireless NICs probably also come in other configurations as well.
Brand and configuration is not important
The brand and the physical configuration of the wireless NIC is not important for this project so long as the NIC provides compatibility with the IEEE 802.11g wireless specification.
Reset the router
In this project, you will begin by resetting the router to its default factory configuration.
Access the administrator panel using wired networking
Then you will access the administrator panel of the router using an RJ-45 patch cable and a browser program on your computer. You will observe, but will not modify any of the configuration settings for the router.
| 01/19/07 Special update for NRG Wireless lab: Because we will be operating three different Linksys routers in close proximity in the lab, it will be necessary for you to make changes to the SSID and channel numbers on each router to keep them from interfering with one another. I will provide the instructions for doing this shortly without providing much in the way of an explanation. You will find the explanation in future lab projects. Otherwise, you will leave the factory settings for the router intact during this project. |
Then you will exit from the administrator panel, close the browser, and remove the patch cable that was connecting the computer to the router.
Access the administrator panel using wireless networking
Next, you will cause cause your computer to make an RF connection to the router via the wireless NIC.
Once again, you will open a browser and use it to access the administrator panel on the router.
Wireless communication available with factory settings
This will demonstrate that your computer has the ability to communicate with the router via either a wired NIC or a wireless NIC when the router is configured with the default factory settings.
You will connect and disconnect from the router several times in succession to become familiar with that process.
An unsecured network
Along the way, you will learn that the default factory settings provide an unsecured connection between the computer and the router.
You should not operate the router in this mode for any extended period of time because it makes it possible for others to break into your computer and your network.
Apply power to the router
There is no on-off switch. Power is applied as soon as you plug the power adapter into the power receptacle and plug the other end of the power cord into the connector on the back panel of the router.
The back panel of the router
The back panel of the router is shown in Figure 1. The power connector is on the right side next to the vertical antenna.
|
Reset the router
Press the Reset button on the back panel of the router and hold it down for at least five seconds to assure that the router is reset to the factory configuration.
The Reset button is a small recessed brown button, which is shown on the left side of Figure 1.
Connect a cable to the router
Connect a regular RJ-45 patch cable between the wired NIC connector on the computer and one of the four wired network connectors labeled 1 through 4 on the back of the router in Figure 1.
Local area connection is now connected
This should cause WinXP to display an information bubble indicating that the Local Area Connection is Now Connected, or words to that effect. The bubble should be pointing to an icon that looks like a pair of computer monitors in the system tray.
Browse to the router
Open your browser and point it to http://192.168.1.1/. This should produce a login dialog similar to that shown in Figure 2.
(The actual appearance of the dialog will depend on the browser being used. The dialog shown in Figure 2 was produced by a Firefox browser.)
|
Enter the default password admin
Leave the user name blank, enter the default password admin, and press the OK button.
The administrator panel should open
This should open a web page on the router that looks like Figure 3.
This is the default view of the Linksys router administrator panel.
|
Restricting access to the administrator panel
By default, the administrator panel can be accessed either via cable or via wireless.
However, there is a router configuration setting that can be used to cause this panel to be accessible only via cable. This feature can be used in addition to the password to help protect the panel from unauthorized access. This is particularly important for wireless installations that are open to the public, such as in restaurants, for example.
Administrator functions
All, or at least most of the available administrator functions can be performed using this panel.
Future laboratory projects will deal with some of those functions.
| 01/19/07 Special update for NRG Wireless lab: Each router that will be used in the lab has a sticker on the top. The routers are labeled R1, R6, and R11. Do the following to keep the routers from interfering with one another when being operated in close proximity with one another:
|
Demonstrates accessibility via cable
At this point, we have demonstrated that it is possible to access the router's administrative panel via RJ-45 patch cable with factory configuration settings.
Thus, you have this type of access when you first take the router out of the box and apply power.
Disconnect the patch cable
Now disconnect the patch cable from the router and try to refresh the page on your browser. You should get an error message similar to that shown in Figure 4.
|
Once again, the exact format of the error message will depend on the browser that you are using.
Did you not get the error message?
Note, however, that if you have an active wireless connection to the router, you probably won't see the error message in Figure 4. Instead, the panel will probably be accessed via the wireless link instead of via the now-disconnected cable.
Make a wireless connection to the router
There should be two different network icons in your system tray.
Assuming that there is no network cable connected to your computer, one or both of those icons should indicate that the network connection is disabled by the inclusion of a red X in the icon (or possibly by some other visual clue).
If either icon is missing the red X, (or is otherwise not showing to be disabled), one of the NICs is involved in an active connection to a network.
(You can also learn the status of each NIC by pointing to the icon with a mouse and waiting for a tooltip to appear.)
The wireless NIC icon
The icon that is associated with the wireless NIC is slightly different from the icon that is associated with the wired NIC. In particular, on my machine, it looks like a single computer monitor with some circular lines indicating that radio waves are being transmitted.
(You can also point to the icons with your mouse and a tool tip will appear identifying which is the wireless icon and which is the wired icon.)
Click the wireless icon
This should cause a dialog similar to that shown in Figure 5 to appear on the screen.
|
Possibly a different dialog will appear
Note, however, that if your computer was already connected to the router via the wireless NIC, the dialog will be different from that shown in Figure 5. It will probably look more like Figure 6.
(It is also possible that depending on prior conditions, you may get a different dialog from the one shown in Figure 5. In that case, you may have to work through more than one dialog to finally get to the dialog shown in Figure 5.)
Press the Connect button
If the computer is not connected to the router, press the button labeled Connect. After a pause and some progress indicators showing on the screen, the dialog should change to look like Figure 6.
|
Unsecured wireless connection
At this point, you have an unsecured wireless connection to the router. You will learn how to secure the network in future laboratory projects. Suffice it to say that it would not be wise to operate a network in this unsecured configuration for any extended period of time.
Disconnect and reconnect several times
Disconnect and reconnect from the router several times to get a feel for this process.
Be sure to reconnect before executing the next step.
Point your browser to http://192.168.1.1/
Once again, point your browser to http://192.168.1.1/. The administrator panel for the router should open in your browser and should look similar to Figure 3.
At this point, you are communicating with the router using your wireless NIC instead of your wired NIC.
Disconnect again and try to access administrator panel
Disconnect from the router and try once again to access the administrator panel. It should not be possible and you should get an error message to that effect.
Communicating using default Linksys factory settings
This project demonstrates that the Linksys router is ready to communicate with your network of computers, (which are equipped with IEEE 802.11g NICs) via wireless as soon as you take it out of the box and apply power.
(It is also ready to communicate with your network of computers using wires as well.)
An unsecured network
However, as indicated in Figure 6:
"This network is configured for open access. Information sent over this network may be visible to others."
Therefore, you should not use the network in your home or in your business in this configuration.
Rather, you should learn how to make configuration changes at the administrator panel to secure your network before using it.
That, among other things, will be the purpose of future laboratory projects.
Copyright 2005, Richard G. Baldwin. Reproduction in whole or in part in any form or medium without express written permission from Richard Baldwin is prohibited.
Richard has participated in numerous consulting projects and he frequently provides onsite training at the high-tech companies located in and around Austin, Texas. He is the author of Baldwin's Programming Tutorials, which have gained a worldwide following among experienced and aspiring programmers. He has also published articles in JavaPro magazine.
In addition to his programming expertise, Richard has many years of practical experience in Digital Signal Processing (DSP). His first job after he earned his Bachelor's degree was doing DSP in the Seismic Research Department of Texas Instruments. (TI is still a world leader in DSP.) In the following years, he applied his programming and DSP expertise to other interesting areas including sonar and underwater acoustics.
Richard holds an MSEE degree from Southern Methodist University and has many years of experience in the application of computer technology to real-world problems.
-end-
Figure 2 Router login dialog box
Figure 3 Linksys router administrator panel.
Figure 4
Figure 5 Wireless Network Connection dialog.
Figure 6 Wireless Network Connection dialog