C++/VB - Enabling/Disabling network interface programatically

Asked By Cosmi

17-Mar-08 04:06 AM

Hi,

Several weeks ago I started a virtual NIC driver that is supposed to
communicate with a user mode module pass the packets back and forth. I've got
the driver running but now I need to make the virtual NIC run only if the
user mode module is running and disable the NIC when the user mode app closes
down.
So if anybody tries to enable the virtual NIC manually I should check
somehow from KM if the user app is running. If not return with failure
When I start the user app it should start the driver also automatically and
start the packet exchange between them.

Any idea how can I implement these things?

Thanks,
Cosmin Onea

18-Mar-08 05:15 AM

You may start or stop NIC driver from user mode - each time your UM
application gets started or closed. Look at devcon sources in WDK src/setup
directory.

As for checking against presence of UM application ... Basically, checking
against presence of UM application is not enough. If I am a smart guy, I can
rename any executable, say calc.exe into yourapp.exe, run it, put into
background, and enable your NIC - this will work, is not so?

You may implement an own protocol between UM application and your KM
component. For example, UM application sends IOCTL to driver when it's up,
and send IOCTL when it's down (unfortunatly, this would not work in case of
force termination, but it just depends upon requirements). This will enforce
that exactly "some magic" application is required to run your NIC.

--
V.
This posting is provided "AS IS" with no warranties, and confers no
rights.

18-Mar-08 11:52 AM

Ok, I'll have a look at the sample.

The requirement sounds like:
application is not started."
When the driver loads the driver entry and Initialize is executed. How can I
check  that the user app is running at this stage? I'm afraid I can't IOCTL
from the user mode at this stage.
If you are familiar with hamachi they do it somehow. If you try start the
nic it says connection failed and back to disabled mode if the user app is
not running.

I need to investigate more.

Thanks,
Cosmin

18-Mar-08 12:00 PM

You can track process creation && termination using
PsSetCreateProcessNotifyRoutine && PsSetLoadImageNotifyRoutine functions. In
PLOAD_IMAGE_NOTIFY_ROUTINE handler you can get the path of an image which is
loading, and set your driver into corresponding state if specified image
get's executed.

--
V.
This posting is provided "AS IS" with no warranties, and confers no
rights.

22-Mar-08 12:14 AM

This may work but looks too complicated. Perhaps this requirement could be
turned down
as not reasonable.
A non-admin user can't enable a physical netcard anyway, and admins can do
everything.
So the client app should be a service, or use a service.

Regards,
--PA