Re: [Gumstix-users] interfaces file

[Dave H. <dhy...@gm...>]

Hi Brendan,

On 10/23/06, Brendan Maguire <mag...@gm...> wrote:
> Sorry about the delay in getting back to this. I changed the mwlan0
> entry from dhcp to static IP. I think the change was from:
>
>  iface mwlan0 inet dhcp
>
> to:
>
>  iface mwlan0 inet static address 192.168.0.40 netmask 255.255.255.0
>
> But I may have made a syntax error in the file, I couldn't be sure.
> Could this be the problem? What I'm really asking is if this file was
> changed or there was an error in it, should I not still be able to see
> the device there when i type "ifconfig -a"? I would have thought that
> my computer would at least realise there was something plugged in!

In order for a devce to show up in the ifconfig -a listing, it
requires that the appropriate drivers have been registered, and
actually doesn't require an entry in the /etc/network/interfaces file
at all.

The /etc/network/interfaces file is used by the ifup anf ifdown
commands. When the system starts it does an ifup -a which scans the
interfaces file and attempts to bring up all of the entries which were
declared auto. It will also try to automatically load the appropriate
modules required for a network interface.

What causes an entry to show up in ifconfig, is that the appropriate
modules were loaded and this may or may not require hardware to be
present.

The example that you gave above seems to be missing the pre-up stuff
which calls iwconfig, which is cruicial for wifi operation.

Here's an entry which I tested and verified that it works properly.

auto mwlan0
iface mwlan0 inet static
       address 192.168.1.99
       netmask 255.255.255.0
       gateway 192.168.1.1
       pre-up /sbin/iwconfig $IFACE key 26-hex-digits-here key open
essid "MyLANsESSID" txpower 100mW

The last line (pre-up) is a long one and may wrap

This particular entry was for using 128-bit WEP. If you're using an
open AP, then you can drop "key 26-hex-digits-here key open". Using
essid any will also connect to the first available AP.

-- 
Dave Hylands
Vancouver, BC, Canada
http://www.DaveHylands.com/