Wireless Bridge

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Contents

Introduction

Wireless Bridging is used to connect 2 LAN segments via a wireless link. The 2 segments will be in the same subnet and looks like 2 ethernet switches connected by a cable, to all computers on the subnet. Since the computers are on the same subnet, broadcasts will reach all machines allowing DHCP clients in one segment to get their addresses from a DHCP server in a different segment. You could use a Wireless Bridge to transparently connect computer(s) in one room to computer(s) in a different room when you could not, or did not want to run an ethernet cable between the rooms. Contrast this with Client Mode Wireless, where the local wireless device running DD-WRT connects to the remote router as a client, creating 2 separate subnets. Since the computers within the different subnets cannot see each other directly, this requires the enabling of NAT between the wireless and the wired ports, and setting up port forwarding for the computers behind the local wireless device. Segments connected via Client Mode Wireless cannot share a DHCP server.

In the case in which we are interested, a wireless device running DD-WRT such as a WRT54G is configured as a Wireless Bridge between a remote wireless router (of any make/brand) and the ethernet ports on the WRT54G.

Instructions

A very good forum post was made by kkennedy070790 about running a WRT54G using DD-WRT as a wireless bridging.

Find it here: http://forum.bsr-clan.de/viewtopic.php?t=1750&highlight=bridge#11522

(editorial note: the above link doesn't exactly match the directions below. That's confusing. For example, the bsr-clan post says nothing about adding a mac address to the filter list on the base station)

A very simple step-by-step description to connect a WRT54G running DD-WRTV23:

To enable Brige-Mode between 2 WRT54G, one WRT54G has to be in AP-Mode in Wireless/Basic Setup. The other one is joining the first WRT54G as "Client-Bridged"

1. Add WAN MAC-Address of WRT54G to your mac filter list on your base station.

2. Connect to your WRT54G (normally 192.168.1.1) by wire which should act as client bridge.

3. Enable Wireless Security (in Wireless/Wireless Security) as used, eg. WEP and configure it as used in your local network.

4. In Wireless/Basic Settings choose "Client-Bridged" as Wireless Mode and set SSID, Wireless channel and Network Mode can be set to same values as your Base Station, normally Auto / Mixed.

Thats all. On next wired connect to your wrt54g you should get an IP Adress from your network.

If you want to configure your new wrt54g bridge again, set a static ip adress of 192.168.1.x network to your client and you can reach the wrt54g as 192.168.1.1. by wire.

Important: If you want to use WPA encryption on your client bridge, make sure your key is no longer than 63 caracters even if you are using an HEX key. (Not sure if this is a bug or not 05/08/2006)

V23 Firmware

In the V23 firmware, you can set up the bridge from the Wireless->Wireless Mode menu. Just select "Client Bridged". This will automatically turn off DHCP. Note that only the Network Mode (b/g) and SSID settings are used in Client Bridged mode.

See notes on a 2.3 attempt at Client Bridged with a Belkin A/G AP in Bridge Install

I am also linking these in Client Bridged

New to Client Bridging?

Here's some extra information about client bridging and some, perhaps unexpected, side effects. (If you're a wireless networking wizard, you'll know this already.)

When you've switched to Client Bridge mode you won't be accessing the remote AP until your IP changes unless your box and the remote network are on the same subnet. For example, say you have:

linksys box IP:         192.168.1.1
your computer:          192.168.1.100
remote network gateway: 10.0.0.1

Once you've made the configuration changes in your router, you'll need to get a new address to access the remote network. A simple way to do this with most computers is to unplug the network cable count to 10 and plug it in again. When the cable is plugged in again, it will get a new lease, but this time from the remote computer. For example, it will get an address in the 10.0.0.x range, e.g. 10.0.0.100. Now you'll be able to use the internet over the wireless link as you expect.

However, you won't be able to access your Linksys to administer it. The solution is to turn off DHCP and use a static IP (e.g. 192.168.1.99), or, alternatively, assign an address for your Linksys from the remote subnet (e.g. 10.0.0.2). Be careful, however, not to pick an address already in use.

Future

This page should eventually contain the information in the link above with the original link sited, along with any DD-WRT specific updates to the instructions.

External References

Wireless Bridging Forum Post by kkennedy070790