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Hi ya'll! I'll start with telling you what my end goal is. I am setting up a ClearOS router for home use. I am using an old comp with three ...
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  1. #1
    Just Joined! paveway's Avatar
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    Need help with the logic of bridging interfaces


    Hi ya'll! I'll start with telling you what my end goal is. I am setting up a ClearOS router for home use. I am using an old comp with three PCI network interfaces. Two of them are WIRED and one is WIRELESS. I would like to use the wireless NIC as an access point.

    So far, I have gotten this router to work beautifully over-the-wire. The external interface gets my IP address and the internal interface serves my desktop computer. I will later add a switch to the internal interface, but for now I am setting it up with only one computer plugged in.

    From the tutorials I have read, in order to accomplish what I want with the wireless NIC, I need to bridge my wireless NIC and the wired NIC. The problem is, the tutorials are vague as to the details pertaining to IP addresses and subnets. Which interface is serving as the gateway? Does each NIC on the bridge have to be on a different subnet? How is the data flow logically set up?

    Is is like this:


    Modem
    |
    eth0
    (router)
    eth1
    |
    bridge0
    |
    wlan0

    or is it more like this?

    Modem
    |
    eth0
    (router)
    bridge0 --- eth1
    |
    wlan0



    I want my network to have IP addresses in 10.10.1.1. Who should be set up with DHCP? Who should have static IP addresses? Who is the gateway?

    Thanks in advance for any help provided!
    Last edited by paveway; 10-27-2013 at 05:20 PM.

  2. #2
    Linux Engineer
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    You don't want to bridge your wireless connection to your ethernet connection. You want to route the connection.

    Since eth0 has your public IP, something will have to perform a NAT. This would typically be iptables, but I'm not sure what software ClearOS would provide.

    Anyhow, setup the wireless interface to be an access point: Debian / Ubuntu Linux: Setup Wireless Access Point (WAP) with Hostapd

    The part about bridging is if your modem is also providing DHCP. IE, if eth0 has a 192.x (or other) local IP, then setting up a bridge would be fine. If eth0 has a public IP, then you'll need to setup a DHCP service on your wireless interface and route the traffic to eth0 using a NAT.

  3. #3
    Linux Engineer
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    Okay, re-read your post. Apparently ClearOS is an actual hardware router (or so it appears).

    In your case, your first map is correct.

    bridge0 would be on the PC you're trying to setup as the access point.

    You would want to bridge eth0 and wlan0 on the PC that's acting as the access point in accordance to the instructions provided in the article I linked.

  4. #4
    Just Joined! paveway's Avatar
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    If I bridged eth0 (My external interface) and wlan0, wouldn't that make wlan0 face external as well?

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