Some time ago, I discussed how to turn one of the most popular – though somewhat outdated – routers into a wireless bridge and/or a wi-fi extender.  The Linksys WRT54G ended up in tens of thousands homes and businesses (if not more), but with both wireless needs and wireless speeds increasing, many have moved on to more powerful devices.  So what are we to do with these old workhorses?  Most of them are still in perfect working order.  Sure, you can sell them for a few bucks that won’t even make a dent in the purchase of your next router, or you can repurpose your WRT into a bridge or wi-fi extender for your home’s growing wireless needs.

In the first article, I discuss in greater detail just what a bridge (and wi-fi extender) is and what one might use them for.  Maybe you need to set up wired connections at other places in your house where running cables from your primary router is impractical?  Maybe your wi-fi signal is weak in certain parts of your house and you want to extend its reach a little further?  Maybe you just want to isolate certain parts of your home’s network?  There are lots to reasons you may need a bridge; if you’ve got an extra router but are unsure if this process is for you, I encourage you to read through my previous article – also take a look at the diagram below to see just what the difference between a router and a bridge is.

This article is going to explain how to deal with a WRT54G Version 4, whereas the previous article only covered versions 5, 5.1, and 6.  Recently I’ve seen several Version 4’s going for as little as $5!  Although the configuration is the same once the DD-WRT firmware is installed, the installation process is a little bit different and actually much simpler.  How do you know which version you have?  Just flip it over and look at the bottom:

Materials

• An internet connection and a primary router that supplies that connection to your household
• Linksys WRT54G v4 router
• Ethernet cable
• PC or laptop
• DD-WRT Firmware – Mini and Standard versions

Getting Started

I’m not going to go into the same level of detail here about how to prepare for the installation.  For more detailed instructions, read through Before We Get Started in the previous article as well as Step 2.b and Step 2.c.  For those with a little more experience, you can follow my abbreviated version of the instructions as follows.

First you’ll want to familiarize yourself with the settings of your primary router such as security mode and algorithms, shared key, etc.  You won’t need these yet, but you will during the configuration step, and it’s easier to go ahead and take note of these beforehand.  See Before We Get Started for more details.

You’ll also need a couple of files on hand.  We’ll be doing most of this process while not connected to the internet, so it’s important to gather up everything ahead of time.

DD-WRT receives updates from time to time, so there may be newer versions depending on how old this article is.  You can always go to DD-WRT’s download page – http://www.dd-wrt.com/dd-wrtv3/dd-wrt/downloads.html – and find the latest software for your router.  This list can be a little confusing if you don’t know what you’re looking for -here are the two files you’ll need and current links to them:

• dd-wrt.v24_mini_generic.bin (Mini version for initial upgrade)
• dd-wrt.v24_std_generic.bin (Standard Firmware)

Stick these 2 files somewhere that you can find them easily.

Important:  From this point forward we will be disconnecting from the internet.  Gather what you need now as disconnecting and reconnecting over and over will be a major pain!  Read through everything first, download what you need, and keep all relevant web pages up and open!

Step 1: Prepping the Router

First we need to disconnect completely from the internet.  If you’re using a PC without wireless capabilities all you’ll need to do is unplug the Ethernet cable.  If you’re using a computer or laptop with wireless, it’s best to simply shut off your wireless card completely; simply disconnecting from your network isn’t enough, it needs to be turned off completely.

Once you are completely disconnected, you’ll need to change your adapter settings.  Uncheck the “auto assign IP” option and manually set your computer’s IP to 192.168.1.7.  For the Subnet Mask, enter 255.255.255.0.  If you’re unfamiliar with how to do this, use a search engine for instructions on how to manually assign an IP address to your computer or see Step 2.c in the previous article.

Go ahead and connect the power cable to the router but don’t plug it into your computer just yet.  Instead, do a hard reset.  (Step 2.b of previous article.)

At this point we’re going to connect the router to the computer and it’s important that you’re not connected to the internet.  Plug one end of the Ethernet cable into one of the 4 LAN ports on the back of the router (not the WAN port) and plug the other end into your computer.  After a few seconds your computer should verify that you have a Local Area Connection though no internet access.

Once you have the router connect, power cycle it.

Step 2:  Installing DD-WRT

This step is considerably less involved than our efforts with a version 5, 5.1, or 6.

Open a new browser window and navigate to 192.168.1.1.  This the default address for the router, and you should be presented with the default Linksys firmware.  If you see “Management Mode,” you’ll need to perform another power cycle and try again.  You’ll see a prompt for username and password; leave username blank and type in “admin” for the password.

Now click on “Administration” at the top.  On the new sub-menu, click “Firmware Upgrade.”

Click “Choose a file” and find the mini version of DD-WRT.  In our case it’ll be the file dd-wrt.v24_mini_generic.bin.  Now click “Upgrade.”

This process can take a while and the browser may appear to lose its connection to the router midway through, but let it run its course.  After a few minutes you should get either an “Upgrade Successful” or “Upgrade Failed” message.  Either way, wait a full five minutes before doing anything else.  Even if you see “Upgrade Failed,” it may still be successful – just wait those 5 minutes!

Again navigate to 192.168.1.1.  You should see a completely different interface now.  If not, try a hard refresh on your browser (press F5), clearing your browser’s cache, or even using a different browser.  If the DD-WRT interface is not loading, try power cycling the router again and again upgrading the firmware if confronted with the default Linksys interface.  If this doesn’t work, do a hard reset and try again.

Once you see the DD-WRT interface for the first time, power cycle the router.  Navigate back to 192.168.1.1.  You should still be able to see the DD-WRT interface.

When you see it for a second time, perform a full hard reset.

Now go back to 192.168.1.1.  You should be presented with an opportunity to create a username and password for this router.  Write this down somewhere and keep it safe; you’ll need it to access this particular device in the future.

At this point you are free to use the mini version of DD-WRT at your leisure.  However, you are also free to upgrade to the full version of DD-WRT since the original firmware has been wiped.  I don’t know what the differences between the versions are, but I’ve set up my other bridges using the Standard version, so I recommend doing the same.  Once you’ve got your username and password set up, it’s time to upgrade again.

Step 3:  Upgrading to Standard Version

When dealing with the Version 4, the standard firmware  limits how much data can be installed on the device.  But now that we’ve replaced the existing firmware, we can install whatever the router will physically hold, including the Standard DD-WRT.

All we need to do is go to the “Administration” tab, then the “Firmware Upgrade” sub-tab.  From here, click “Choose File” and find dd-wrt.v24_std_generic.bin, select it, and click “Upgrade.”

The only thing left is to properly configure the device for a bridge.  I’ll provide bullet points below for anyone familiar, but if this is your first time see Step 3 of the preceding article complete with detailed explanations and pictures.

Step 4: Configuration (for Wireless Bridge)

• Wireless –> Wireless Security:  Set Security Mode, Algorithms and Shared Key (same as primary router); SAVE                                                                                                             
• Wireless –> Basic Settings:  Wireless Mode = Client Bridge, set Network Mode and SSID (same as primary router); SAVE, APPLY SETTINGS
• Setup –> Basic Setup
  • Local IP Address – enter desired address for bridge
  • Subnet Mask – 255.255.255.0
  • Gateway – leave blank for now
  • Optional: set time one
  • Optional:  select Switch WAN port to LAN
  • SAVE, APPLY SETTINGS
• Login to the router again from the new address (if applicable)
• Setup –> Basic Set up
  • Now fill in Gateway with the address of your primary router – should be 192.168.1.1 in most cases; SAVE.
• Security –> Firewall
  • Under Block WAN Requests, check only Filter Multicast.  SAVE.
  • Under Firewall Protection, make sure SPI Firewall is disabled.
  • SAVE, APPLY SETTINGS
• Setup –> Advanced Routing: Set Operating Mode to Router, SAVE.

Step 5:  Testing the Connection

Again, this is outlined in greater detail in Step 4 of the previous article.  Briefly though, here’s how you’ll go about making sure your bridge works.  You should still be disconnected from the internet – make sure your wireless capabilities are completely off or that no network cables are plugged in aside from the router/bridge.

First, return to your adapter settings on your computer to “Automatically Obtain IP Address.”  You may also need to reset the “Obtain DNS Server Address Automatically” as well.

If you’re lucky, your computer may immediately recognize the connection and connect you to the internet.  More than likely however, you’ll need to power cycle your router.  When it’s had a chance to reboot, try visiting a few websites.  If this still doesn’t work, try power cycling again.

If it still doesn’t work, the most likely cause is a discrepancy between the settings of DD-WRT and those of your primary router.  Continue to check and recheck this information.  If you can’t seem to access the bridge via your browser, go back to assigning a static IP to your computer and trying again.  When all else fails, do a hard and go back to the beginning of the configuration instructions.

Step 6: Wi-Fi Extender or Virtual Access Point (Repeater Bridge)

Once you’ve verified that your connection is working, you can tweak a few more features to make it act as another access point.  It will still retain all its bridge properties but will act as a completely separate access point for wireless devices to connect to.  The only catch is that the bandwidth for wireless devices connected to this new AP will only have access to half of your original bandwidth since it must mediate data both coming from and going to your primary router.  For this reason, they are also known as a “repeater bridge” or “repeater.”  However, wired devices will still have access to 100% of your original bandwidth.

Again, this process is covered in more detail in Step 5 of the first article; this is only for those familiar with the process.  Also there is no need to disconnect from the internet at this point; in fact, you don’t even need the router physically connected to your computer to do this.  We’ve already done all the hard stuff – now we’re just going to tell the device that we want it to be its own access point as well.

• Everything should already be configured exactly as described above.  These instructions will assume that you have already made these adjustments and established that the connection is successful.
• Navigate to the router-bridge’s address (the address that we defined for the device earlier) and log in.
• Wireless –> Basic Settings: For Wireless Mode, select Repeater Bridge.  SAVE.
  • A new Virtual Interfaces section should pop up.  Click Add.
  • Enter SSID for the new access point; should be different than primary router.
  • SAVE.
• Wireless –> Wireless Security
  • A new Virtual Interfaces section should be here as well.
  • Security Mode, Algorithms, and Shared Key should all match those of primary router.  (Will also be the same as those in Physical Interfaces above.)
  • SAVE.
• Setup –> Basic Setup:  Local DNS should match the address of primary router – 192.168.1.1 in most cases.  SAVE.
• Services –> Services: For DNSMasq, mark Disable.  SAVE, APPLY SETTINGS.

That’s it!  Your new AP should show up with the SSID you defined and the password will be the same as that of the primary router.

You can now treat this router however you like – unplug it, turn it off, whatever.  These configurations will persist unless you perform a hard reset or otherwise fiddle around with the settings.  Remember that a repeater bridge will possess all the same functionality as a standard bridge, so if you think you may ever want an extra access point, go ahead and go through with the setup.

That’s it for converting the Linksys WRT54G v4 to a bridge using DD-WRT!  While it’s all fresh in your mind, be sure to write down the IP address of the device and the username and password!  You’ll need these if you ever want to access the settings again; of course if you do forget you can always perform a hard reset and redo the configuration (though the installation of DD-WRT will still be intact).  Like all routers, these may get “stuck” from time to time and need a reboot, don’t be alarmed.  Take a look at my previous article for suggestions on how to make the most of these bridges.  They come in extremely handy when dealing with devices that need wireless adapters to function properly or things like game consoles that “prefer” a wired connection.  Essentially you can view this as one big universal wireless adapter that can “adapt” up to 5 wired devices at once!

For more information about what DD-WRT can do in general (it’s useful for much more than turning routers into bridges and access points), I encourage you to check out the DD-WRT Wiki.