Wireless ethernet bridge

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shuiend
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Wireless ethernet bridge

Post by shuiend »

http://linksys.com/products/product.asp ... 6&prid=432 I am thinking about buying one of those for my room then hooking a switch up to it to get more acces in my room. Right now i only have a wireless pci card so only of my my computers can get online. I was wondering if it was possible to make one of these devices in linux? I allready have a DHCP server so i dont want another one i just want a computer to usethe wireless to get the signal then pass it out through a diffrent network card. Is this even possible?

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Post by Void Main »

That's a wireless bridge. What these are usually used for is extending a network without using a cable. For instance you might want to hook up a switch in a far corner of your second floor and make it part of your network on the first floor opposite corner, but without running any cable. You can get two of these bridges, plug one into the switch on the first floor and connect the second one to a switch on the second floor. It would be the same as if you had a hard wire running between the two switches.

I'm not sure if this is what you are after or not but that's how I've always used them (places where it's difficult to run a wire). In this scenerio your machines should have the same access regardless of which switch they are plugged in to (you can use your DHCP server and internet connection on the first floor to serve all machines on either floor).

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Post by shuiend »

I know what they are used for. I run a wireless network in my house. In my room i have 3 computers and my ps2. I would like them all to be able to get online but i dont have the cash right now to get one of the bridges. So i was wondering if it is possible to make one with a linux comp. i all ready have the wireless pci card and another network card and such so all i need to know is howto go about doing it on the software saide.

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Post by Void Main »

Sure it's possible. There are two ways you can do this, both require a second network interface. The first way is to configure your Linux box just as you would if it were going to be your Internet gateway for your house (IP Masquerade). The second way and probably better is to configure it as a bridge:

http://bridge.sourceforge.net/

I only have experience with the first method and have never tried configuring a Linux machine as a bridge. It appears to be extremely simple though:

http://bridge.sourceforge.net/docs/bridge.html

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Post by shuiend »

Thanks thats the info i needed. I will be going through this info probally this weekend and see if i can get it set up. Now i just got to go get a cheap switch.

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Post by shuiend »

Thanks so much voidmain for that info. I got the comp set up as a brdige in no time at all. Now my trouble is with the switch i got. I dont know which port on it is uplink. i got a 12 port 3com switch from my skool. The model number is 3c16942a and i cannot find info on it at the 3com site. So would u have ne clue which port is uplink i rather not have to sit here and test them all.

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Post by Void Main »

The only reason you would need an uplink port is if you are hooking two switches up together. If that indeed is what you are doing you have two choices. 1) plug one switch into the other's uplink port (if you can find it) with a normal straight through patch cable. or 2) use a crossover cable and just plug into a normal port on each switch. If you have a crimper, a length of cat5 and a couple of RJ45s you can make your own crossover cable. If you are not plugging two switches together then you don't want to use an uplink port anyhow (an uplink port is nothing more than a normal port with a crossover, if you plug a crossover cable into an uplink port it would end up being a normal straight through port).

Having said that the uplink ports on switches are usually marked with an "X" for Xover (or crossover). The 3Com 12 and 24 port switches I used to use were very clearly marked but I usually didn't use uplink ports in those switches, I had fibre modules in the back that I connected to core switches.

Having said all that :) it appears that all 12 ports are MDIX (cross-over). Here's the manual:

http://support.3com.com/infodeli/tools/ ... anual.a03/

I believe this to mean that it is a normal switch with no uplink ports and you'll indeed need a crossover cable to plug two of them together. Again, if you are not directly plugging your switches together (your linux box with two NICs is between them) then use regular straight through patch cables. NIC->Switch use straight through, Switch->Switch use Crossover (unless you have an Uplink port). That was way too many words and more than you asked for. Sorry about the verbosity.

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Post by shuiend »

Thanks that was alot of good info that i actually did not know. I am just really starting tol learn about this whole networking thing.
So you say i need a crossover cable then. I shall go get one from a friend untill i can get to skool and make one. What i want to do is run from the linux bridge computer to the switch. Then from the switch to all the other computers. Going form the linux bridge through the switch will still pass on the dhcp signal wont it?

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Post by Void Main »

By definition a bridge should pass DHCP traffic. I am still confused as to how you are hooking up your switches. If you are not plugging your switches together directly then you don't need a crossover cable. Unless I misunderstand something I thought the entire point of the whole exercise was to use your linux box as a wireless bridge between the two switches. If this is the case then you shouldn't need any crossover cables, all you should need are straight through patch cables.

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Post by shuiend »

The linux box is set up as a wireless bridge. I get that set up and on all fine. The bridge then is going to plug into the switch. Then from the switch it will go to my other computers. Would i use cross over or normal patch cable to go from the bridge to the switch? I have now tried both of them and my other redhat 8 box cannot get the dhcp signal.

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Post by Void Main »

You want a straight through cable between your Linux box and the switch. As far as it not passing traffic it's very possible that your wireless card/hub does not support it as it would need to allow multiple MAC addresses. There is a FAQ entry about a WaveLAN wireless setup not working for this reason. What is the make/model of your wireless card and hub? I can try and do a little digging and see what I can come up with. Here is another related message on the bridge mailing list:

http://www.math.leidenuniv.nl/pipermail ... 03051.html
http://www.math.leidenuniv.nl/pipermail ... 03052.html

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Post by shuiend »

I have a dlink DWL-520. I was reading in those 2 links about maybe firmware update. I have yet to do an update for the card so that may be it. I will go check that out in a little bit. I hope if there is an update i can do it from linux cause i dont got windows on this comp and really dont want to move the wireless card for just an update. Oh yah the card is a prism2.5 card. I believe dlink changed the chipset on the dwl-520 to something else but i am positive mine is prism based. The drivers i am using for it are from Linuxwlan.com just so you know. I will be doing some more reading on this later tonight.

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