Re: usb0 Connection DHCP Problem

[Bob Cvengros <rcvengr2 illinois edu>]

Thank you for your reply.  I found out that my device has a new MAC address every time it starts up, which is often enough. Every time this happens NM tries to create a new usb0 connection but fails. If you look at the "Edit Connections..." box through a restart you see several usb0 connections and no real usable connection. This is all with the interfaces file empty. I think that setting my MAC address as static should solve the problem.

Thanks for the help,
Bob

On Tue, Sep 22, 2009 at 11:48 PM, Dan Williams <dcbw redhat com> wrote:

On Fri, 2009-09-18 at 11:09 -0500, Bob Cvengros wrote:
> Hi,
>    I am trying to tether an embedded device running linux to my PC
> using the g_ether usb ethernet gadget. I am running the DHCP server on
> the device side and have been having trouble getting the PC to acquire
> an address properly. I've got it boiled down to a conflict between
> NetworkManager (v 0.7.0.100) and the /ect/network/interfaces file on
> the PC side. When I uninstall NetworkManager and appropriately setup
> the interfaces file the connection works perfectly i.e. the PC can
> acquire the IP address each time I reconnect the physical usb
> connection after a disconnect.  If I comment out all of the relevant
> lines in the interfaces file and just use the network manager it seems
> to work well too. The problem is when both sides are setup to handle
> the usb0 connection. The symptoms are that the usb0 connection will
> only sporattically connect and most time only connects for a few
> seconds and then dies.
>
>    Why does NetworkManager seemingly conflict with the interfaces
> file? Shouldn't they work together? Also, my goal is to build a
> connection that automatically connects the device to the PC without
> actually having to set it up manually through NM's "Edit
> Connections...", is this possible? If so than I can probably just

That should be the way it works; my T-Mobile phone does just this
because it provides a cdc-ether USB ethernet interface, and NM will
handle it just fine with DHCP when I plug it in.

On debian with the 'ifupdown' system settings plugin, you can remove
anything to do with the device from the interfaces file and I believe
that NM will manage the device correctly.  Also check
your /etc/NetworkManager/nm-system-settings.conf file, where there could
be a "managed = false" line (which exists for backwards compat), that
causes NM to ignore any device explicitly listed
in /etc/network/interfaces.

So to get what you want, just remove any reference to "usb0"
from /etc/network/interfaces, basically.

On the windows side, once you have drivers for the device installed, I
*think* you can just do the "Assign address automatically" from the
Network & Sharing control panel in Vista for that device and it'll
automatically connect, just like any other normal ethernet connection.

Dan

-- 
University of Illinois at Urbana-Champaign
Electrical Engineering

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