M and L Adventures

**DISCLAIMER** The following instructions are provided without warranty of any kind. Flashing firmware does not come without risk. I will not be held responsible for any resulting equipment failure or otherwise undesirable results. Proceed at your own risk.

This tutorial explains how I successfully flashed my Linksys WRT54GL version 1.1 with the open source dd-wrt version 23 SP2 VPN firmware (generic). If you happen to have Linksys WRT54GL version 1 rather than 1.1 (you can tell by the serial number prefix of CL7A for version 1.0 and CL7B for version 1.1 per the Wikipedia entry and dd-wrt Wiki), you may have to follow slightly different instructions. The main difference is that you will need to flash to a smaller version of the dd-wrt firmware (the mini version) first due to a flash file size limit on the version 1.0 WRT54GL firmware before flashing to the standard, VOIP, or VPN versions.

As a bit of background information, I’m used a fully patched (as of April 6, 2007) Windows XP Pro with Service Pack 2 (SP2) and Internet Explorer 6 during the firmware upgrade process. The OS and web browser shouldn’t matter that much, but I have heard reports of Firefox causing some problems with the Flash for some people in the past though others have claimed to use Firefox without any problems–just a word of caution.

Before you begin, download the package and version of the dd-wrt firmware best suited to your needs though this tutorial walks through flashing to the open source dd-wrt version 23 SP2 VPN firmware. Once you’ve downloaded the file, go ahead an unzip the files. The zip package contains several files, you will only need the “dd-wrt.v23_vpn_generic” file. We’re going to be using the generic file rather than the wrt54g file because we’re going to be using the web GUI to upload the file.

I recommend verifying the MD5SUM hash of the “dd-wrt.v23_vpn_generic” file to ensure the download wasn’t corrupt or hasn’t been comprised. If you don’t already have a tool to calculate MD5SUMs, I recommend using HashCalc although you must manually compare the sums with this tool unlike another tool I can’t seem to think of right now. The signature of the file should be baf91850d3204fd64b120467425b4a11. If you plan on flashing a different version, you can find of list of signatures on the dd-wrt hashes page.

While your at the dd-wrt website, I recommend printing (or at least saving, not bookmarking, to your hard drive) the following pages for reference since you will not have Internet access during this process:

• How to Flash the WRT54GL with DD-WRT Firmware
• Installation
• WRT54GL Specific Instructions
• Reset and Reboot
• Recover from a Bad Flash

It is best to turn off your firewall and anti-virus during this process to ensure that nothing interrupts the firmware flash. An interruption could cause the flash to fail and brick your router. If something does go wrong you may be able to recover from a bad flash.

Almost forgot to mention, you should ONLY perform the flash through an Ethernet cable using standard http (not https). Do not do this wirelessly (its best to temporarily disable the wireless adapter on your computer). Plug the blue Ethernet (Cat5/RJ45) cable that came with your router into the Network Interface Card (NIC) on the back of your computer and into one of the ports labeled 1, 2, 3, or 4. The “Internet” port on your router should be connected to your broadband source (e.g., cable or DSL modem). Please ignore the extra cable in the picture. It is not needed for the flash to work.

The last item that needs to be completed before uploading the new firmware is to reset your Linksys router to the factory defaults. A few ways to do this exist. I chose to use the standard web interface, but the pressing and holding the reset button on the back of your router for 30 seconds should work just as well (assuming you’re using the factory Linksys firmware, if not be careful). To reset the router to firmware defaults, go to the internal IP address of your router (most likely 192.168.1.1) and login with the user name and password you setup when you first installed the router (if you don’t know those use the reset button method). Once logged in, go to “Administration” tab and the “Factory Defaults” sub-tab. Select the “Yes” radio button next to “Restore Factory Defaults” then select “Save Settings”.

If the reset was successful, you will say a page that says “Settings are successful. You will be returned to the previous page after several seconds.”

Now that everything is setup we can begin the process of actually performing the flash. To upload the firmware, navigate to the “Firmware Upgrade” sub-tab under the “Administration” tab. On this page, select “Browse” to go to the place where you saved the “dd-wrt.v23_vpn_generic” file. Once located, hit open (no brainer). Then hit the “Upgrade” button. Please wait patiently for the upload to complete. Whatever you do, don’t interrupt it. If you’re going to be tempted walk away for a few minutes and come back.

If all goes well, you will great a screen that says “Upgrade is successful”. On that screen hit the “continue” button to, you guessed it, continue. If not successful, simply re-try the same steps or research the dd-wrt wiki for more info.

The next thing you should see is a prompt to login to the new dd-wrt interface. The default user name is “root” and the default password is “admin”. Be warned, I wasn’t able to log-in initially even though I got this prompt.

To confirm that your router is working you should ping it. To ping your router, go to “Start > Run” in windows. Then type in “cmd” and hit “ok”. At the command prompt type in “ping 192.168.1.1″. If the router is online, you will get a ping response that says Packets Sent = 4, Received = 4, Lost = 0 (0% lost).”

Since the dd-wrt web interface didn’t come up right after the flash, I rebooted my computer (the common solution to lots of Windows problems). That didn’t work even though rebooting probably isn’t a terrible idea. What did work was resetting the new dd-wrt firmware back to firmware defaults. To do this you need to hold the reset button on the back of the router while unplugging the router. Continue to hold the reset button as you re-plug in the router. Once the router is plugged in you should continue holding the reset button for 30 seconds to complete the hard reset. I had to do this a couple of times because I didn’t reset it correctly on the first try.

Once reset, go back to Internet Explorer and navigate to 192.168.1.1. At the prompt enter in “root” for the user name and “admin” as the password. Mysteriously, the dd-wrt web interface should come up.

Congratulations, you’ve successfully flashed your router! Since you’ve successfully flashed your WRT54G, you should checkout the Linksys WRT54G Ultimate Hacking guide to make the most out of your new found knowledge of router firmware.

Now that your running DD-WRT firmware, make sure to make use of all the available security features. See my post on Securing Your Wireless Connection and other post in the dd-wrt category.

If you liked this post, consider subscribing to my feed and/or sending me something from my wish list. One other option is to send me a Linksys WRT54GL so I can do some more experiments and write more tutorials. Thanks in advance for your support of this guide & site!!!