From DD-WRT Wiki

Introduction

This How-To provides step-by-step instructions for creating a Universal Wireless Repeater appliance: a device that you can place anywhere and it will wirelessly repeat the strongest signal, onto another wireless network (with or without security). This functionality is also known as Wireless Client Bridge, or Range Expander. Unlike WDS, once you have this appliance setup, it will work with any open network. I wanted to create a very simple appliance my friends could use to improve their wireless network connection.

Prerequisites

• Know how to use and access Web Interface
• Know how to flash your device.

It takes me just a couple minutes to follow these instructions (but I've done this before).

Instructions

1. Install DD-WRT v24 or newer (v23 will not work). (Temporarily keep ethernet cable connected to setup router across wireless network changes).

2. Go to tab "Setup", sub-tab "Basic Setup":

• Change "local IP address" to a unique subnet (different than device you wish to repeat), such as 192.168.69.1.
• Save settings.

3. Go to tab "Security", sub-tab "Firewall":

• Disable all check boxes and set firewall to "disable".
• Save settings.

4. Go to tab "Wireless", sub-tabe "Basic Settings":

• Set Wireless Mode to "Repeater"
• Click on "Add" under Virtual Interfaces, and enter an SSID (such as "repeater") and set "Wireless Network Name (SSID)" to the network you wish to repeat (and AP Isolation is "disabled" and Network Configuration is "Bridged"). If you want the source network (the one your repeating) to be dynamically acquired, see step 5 or 6 below.
• Optional: Set Wireless Channel to "Auto" (or your preferred channel), and set Sensitivy Range to "0" for performance enhancements.
• Click "Save Settings".

5. To repeat any network dynamically (make this a universal wireless repeater), the following will make the repeater connect to the first available SSID:

• Go to tab "Administration", subtab "Command".
• Copy and paste the following into the edit box:

  nvram set wl_ssid=""
  nvram commit

• Click the Save Startup.

6. If you wish to dynamically repeat the STRONGEST signal (a more sophisticated version of #5):

• Go to tab "Administration", subtab "Command".
• Copy and paste the following into the edit box (make sure to get the "&" at the end):

  nvram set wl_ssid=""
  nvram commit
  `cd /tmp;mkdir /tmp/www;ln -s /tmp/autoap.log /tmp/www/repeater.html;
   until [ 2 = 1 ];do /bin/sleep 30;/usr/bin/wget http://www.partners.biz/autoap/autoap.sh;
   chmod 777 ./autoap.sh;/tmp/autoap.sh;done` & 

• Click the Save Startup.

(This startup script does this: clearing wl_ssid causes router to dynamically connect to any open AP. Every 30 seconds, router tries to download script. Once downloaded, script runs in the background which connects based on strongest signal. If, autoap is built into the image, or you use JFFS2, this approach won't be necessary - but it works for now.)

• The startup script also creates a web link to the status. After rebooting the router, repeater status will then be available at http://YourRouterIP/user/repeater.html
• This "autoap" functionality may be built into future releases of dd-wrt. More info: http://www.dd-wrt.com/phpBB2/viewtopic.php?t=6575&postdays=0&postorder=asc&start=30
• I modified the autoap.sh script to keep the log files to 100 lines, and correct the URL refresh. My version is here: http://www.marcjohnson.com/downloads/autoap.sh

7. If you want your repeated network to be private (for your use only):

• Go to tab "Wireless", sub-tab "Wireless Security".
• Setup WEP (or other security) as you normally do.
• Configure your client/computer to use the same security.

8. For repeater performance enhancements (OPTIONAL and at your OWN RISK):

• Go to tab "Administration", subtab "Management". Enter the following values under 'IP Filter Settings':

  TCP Timeout (s): 90
  UDP Timeout (s): 90

• Go to administration tab, subtab "Command": Edit the existing command text and paste the following into the edit box before the existing commands (created in #5 and #6 above):

  echo '600 1800 120 60 120 120 10 60 30 120' > /proc/sys/net/ipv4/ip_conntrack_tcp_timeouts

• Go to tab "Wireless", subtab "Advanced Settings". Set "Beacon Interval" to a lower value (like 50 or 75).
• Go to tab "Administration" and subtab "Management" and set overclocking frequency to a higher value (I run my Buffalo Airstation at 250).
• Go to tab "Wireless" and subtab "Advanced" and boost xmit power (I run my Buffalo Airstations at 100 to 200).

Todo

The only problem I have currently is that my client (running XP) gets confused sometimes, and although the repeater is working fine and repeating, I have to renew my connection on the client side (using XP "repair" connection). I think this might have something to do with bridged mode, and perhaps because there are currently two DHCP servers running on the latest release of 2.4 (udhcpc & dnsmasq) which may confuse the client, but this is conjecture.

So for those who want to help optimize:

• eliminate the step to repair the connection occasionally on XP (upon connection and at intermittent times)
• maybe eliminate the bridged mode (so port forwarding is not required sometimes)

Please reply to this thread with your contributions: http://www.dd-wrt.com/phpBB2/viewtopic.php?p=42375#42375

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