Arch Linux

aaaantoine

Member

Registered: 2008-12-12

Posts: 44

Bridging wifi and ethernet; bring interface up with netcfg

using bridge-utils I was able to establish a bridge between my ethernet port and my wireless interface.  My wireless interface is the source of the Internet connection on the computer, and the ethernet port is going to send that Internet connection to a nearby computer.  My questions are:

Is it possible to bring this bridge up via netcfg, so that the wireless interface connects to the desired router?

If not, how can I use a bridge to bring up a wireless Internet connection using other applications, so that I can write a script to trigger it when I need it?

ngoonee

Forum Fellow

From: Between Thailand and Singapore

Registered: 2009-03-17

Posts: 7,356

Re: Bridging wifi and ethernet; bring interface up with netcfg

I was under the impression that bridging wireless and LAN was not possible, from trying to do something similar previously. Forwarding with iptables seems more suitable for what you're trying to do (share internet connection).

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aaaantoine

Member

Registered: 2008-12-12

Posts: 44

Re: Bridging wifi and ethernet; bring interface up with netcfg

Good to know.  If you have any pointers on where I can find information on using iptables to share my Internet connection (in Arch, preferably utilizing netcfg), please write or send me links.

Meanwhile, back to Google I go a hunting.

Diaz

Member

From: Portugal

Registered: 2008-04-16

Posts: 366

Re: Bridging wifi and ethernet; bring interface up with netcfg

If had created a bridge in my pc between my two network cards on the desktop using netcfg.
Just find the needed commands you need to run and the use them in the PRE_UP or POST_UP or variants options in your netcfg profile.

tomk

Forum Fellow

From: Ireland

Registered: 2004-07-21

Posts: 9,839

Re: Bridging wifi and ethernet; bring interface up with netcfg

Bridging wireless and wired interfaces is definitely possible. Just remember that the bridge is an ethernet device only i.e. you will need to configure your IP address on br0 (the bridge interface) and not eth0/wlan0/etc.

aaaantoine

Member

Registered: 2008-12-12

Posts: 44

Re: Bridging wifi and ethernet; bring interface up with netcfg

So I had this working for a while, and lately I've been using it to bring Internet access to my Xbox 360, which is even more distant from the main router than the desktop I had been using.  It is also a much better use of the bridging in economical terms, since the wireless component for the Xbox is $100 (price gouging jerks...).

Then yesterday I tried it and the Xbox wouldn't connect.  After fiddling around, I found two things out:

1. Since the last time I connected the Xbox to the net, I had ran yaourt -Syu, which updated iptables from 1.4.5-x to 1.4.6-1
2. The specific issue is that, despite the following line in my "ethernet-xover" network profile...

POST_UP="iptables -t nat -A POSTROUTING -o wlan0 -j MASQUERADE ; echo 1 > /proc/sys/net/ipv4/ip_forward ; /etc/rc.d/iptables save ; /etc/rc.d/iptables restart"

... /proc/sys/net/ipv4/ip_forward isn't getting set to 1.  Once I manually set it to 1, the connection works.

So I'd like to take this opportunity to peer review this profile, to a) see why echoing is failing, and b) find out if it is really necessary to restart iptables as shown here.