AP+STA mode for OpenWRT on Broadcom-based Wireless Routers


• The problem: You want to extend your wireless network (e.g. share your
Internet connection further away than your lame ADSL modem/WiFi router
can serve) and you don't like cables.

• The hardware: Your ADSL modem/router with WiFi capability, and a
Broadcom chipset-based WiFi router, such as the fantastic classic
Linksys WRT54GL (now Cisco), running OpenWRT.

• The goal: Use your wireless router as a repeater to extend the range of
your WiFi Internet connectivity.

• The solution: Linux (and the amazing OpenWRT project) already offer
everything that is needed to tackle this in a few simple steps.

• The nitty gritty: We use the Broadcom wireless chipset's capability of
splitting into two WLAN interfaces: one acts as a client (STA) that
connects to your ADSL modem and the other acts as an Access Point (AP).


We will use WPA2 encryption for all WLAN links.

1. Make sure your WRT54GL (or other) is running the latest OpenWRT
firmware, using the Linux 2.4 kernel so that we can take advantage of
the Broadcom driver to do our magic.

At the time of writing, the latest OpenWRT release is 10.03.1
(Backfire). You can download it at:

http://downloads.openwrt.org/backfire/10.03.1/brcm-2.4/

You want openwrt-wrt54g-squashfs.bin if you are installing through
the Linksys web interface (Administration -> Firmware Upgrade)

OR openwrt-brcm-2.4-squashfs.trx if you are upgrading from a previous
OpenWRT version.

Install HOWTO for WRT54G: http://wiki.openwrt.org/toh/linksys/wrt54g

Let's assume that your OpenWRT router uses the default LAN IP address:
192.168.1.1


2. Let's say your ADSL modem has the IP address 192.168.0.1 and that the
WiFi network's name (ESSID) is "MyWireless".

You need to configure two network zones in your WRT54GL, the wan zone
will be accessing the ADSL router and the lan zone will be the WiFi
(or wired) network served by your WRT54GL. They will require different
IP ranges, so the wan zone will use 192.168.0.xxx and let's say the lan
zone will use 192.168.1.xxx .

You can configure this via OpenWRT's LuCI web interface, but the
quickest way will be to login with SSH into your OpenWRT router and edit
the configuration files by hand:


3. Your OpenWRT wireless configuration is found in the file
   /etc/config/wireless and needs to look like this:
   
   

   config wifi-device  wl0
           option type       'broadcom'
           option channel    'XX' # This is your ADSL-WiFi router's channel
   
   config wifi-iface
           option device     'wl0'
           option network    'wan'
           option mode       'sta'
           option ssid       'MyWireless'
           option encryption 'psk2'         # WPA2 for security
           option key        'wifikey1'     # Your existing WiFi password
   
   config wifi-iface
           option device     'wl0'
           option network    'lan'
           option mode       'ap'
           option ssid       'MyWirelessExtender'
           option encryption 'psk2'
           option key        'wifikey2'     # Your extender's WiFi password
   

   
   You can edit this by using vi: (<Esc> followed by :wq saves & exits vi)
   root@WRT54GL:~# vi /etc/config/wireless
   


4. Now you need to edit the network configuration:
   root@WRT54GL:~# vi /etc/config/network
   
   It needs to look like this:
   
   

   config 'switch' 'eth0'
           option 'enable' '1'
   
   config 'switch_vlan' 'eth0_0'
           option 'device' 'eth0'
           option 'vlan' '0'
           option 'ports' '0 1 2 3 5'
   
   config 'switch_vlan' 'eth0_1'
           option 'device' 'eth0'
           option 'vlan' '1'
           option 'ports' '4 5'
   
   config 'interface' 'loopback'
           option 'ifname' 'lo'
           option 'proto' 'static'
           option 'ipaddr' '127.0.0.1'
           option 'netmask' '255.0.0.0'
   
   config 'interface' 'lan'
           option 'type' 'bridge'
           option 'proto' 'static'
           option 'netmask' '255.255.255.0'
           option 'ipaddr' '192.168.1.1'            # Your OpenWRT's lan IP
           option 'defaultroute' '0'
           option 'peerdns' '0'
           option 'gateway' '192.168.0.1'           # Your ADSL modem's IP
           option 'dns' '192.168.0.1'               # Your ADSL modem's IP 
           option 'ifname' 'eth0.0'
   
   config 'interface' 'wan'
           option 'proto' 'static'
           option 'netmask' '255.255.255.0'
           option 'defaultroute' '0'
           option 'peerdns' '0'
           option 'ipaddr' '192.168.0.2'            # Your OpenWRT's wan IP
           option 'gateway' '192.168.0.1'           # Your ADSL modem's IP
           option 'dns' '192.168.0.1'               # Your ADSL modem's IP
           option 'ifname' 'eth0.1'
   

   
   
5. Reboot your OpenWRT and enjoy your new network setup:
root@WRT54GL:~# reboot



6. Optional step:
You may want to hide the original WiFi network. This is not terribly
secure, but it's convenient as you don't see too many SSIDs. Choose
"Hide ESSID" from your ADSL modem's wireless settings. The connection
will still work, but you'll only see the "MyWirelessExtender" network :)