[CentOS] User access to /dev/ttyUSB0

Frank Cox theatre at sasktel.net
Wed Dec 3 19:00:35 UTC 2008

On Wed, 03 Dec 2008 07:02:10 -0500
John wrote:

> Hmm Lets see here... system-config-network Select (highlight) your PPP
> Adapter, then click on Edit. That will be under the Devices Tab. Next Look
> under the General Tab. Place a Check in "Allow all Users to enable or
> disable the Device".

That selection was already in place.

Interestingly enough, using gnome-ppp as a user the I get the "Cannot
open /dev/ttyUSB0: Device or resource busy" error.  But using NetworkManager to
dial the connection works fine to establish the actual connection.  However,
there is no visible indication from NM that the connection has been

On Fedora 10 (where I had this same modem working the other day) I could just
set up the connection using the NM "edit configuration" dialog and when I told
it to connect the NM icon turned into a little cell phone tower.  With Centos 5
I tell NM to "connect to sasktel using modem" and it does its thing and
connects and everything appears to work (ifconfig shows me a ppp0 interface),
but the icon remains the ethernet plug with the line across it and the tooltip
that I get when I mouse over it says "no network connection".  It hangs up when
I tell NM to disconnect, so NM appears to provide full control.

So it seems that while NM establishes the connection, it doesn't realize that
it has done so.  I wonder if there is a way to tell it when the connection

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