Re: [Openvpn-users] OpenVPN win7 routing fails (TUN/TAP device doesn't come up), but only sometimes.

[melbourne <mad...@ho...>]

The first error looks like you can't even open the NCB, because the old NCB
hasn't completed shutting down yet:

>Mon Mar 07 19:15:12 2011 WARNING: Failed to renew DHCP IP address lease on
TAP-Win32 adapter: The name specified in the network control block (NCB) is
in use on a remote adapter.

>From memory:
A NCB is a 'file' pointer: it's the Windows native socket structure.
"Cannot find file" happens when OpenVPN can't use a 'file'  that it has
opened. This happens when you change the IP address of a NCB, and don't
discard the NCB:

> Mon Mar 07 19:23:14 2011 WARNING: Failed to renew DHCP IP address lease on
TAP-Win32 adapter: The system cannot find the file  


So it appears to be a timing related issue internal to OpenVPN, which is
doing an update cycle to fast. The first one, with the invalid NCB, is
recoverable, because OpenVPN retries and gets a valid NCB. You then have to
wait a while and everything goes through.  If you don't want to see the
messages while you wait, you can configure some larger delays in your
config.

The second one "The system cannot find the file specified." may be an
unhandled failure, but it doesn't matter because you received the same IP
address when you renewed the lease. Your routes happen to still be valid, so
it works anyway. As far as I know, there is no configurable delay to avoid
this problem. I think that you can avoid this problem by giving static
leases to all of your clients.  

(david)

 

-----Original Message-----
From: Arthur Murray [mailto:amu...@gm...] 
Sent: Tuesday, 8 March 2011 2:48 PM
To: ope...@li...
Subject: Re: [Openvpn-users] OpenVPN win7 routing fails (TUN/TAP device
doesn't come up), but only sometimes.

On Mon, Mar 7, 2011 at 6:48 PM, melbourne <mad...@ho...> wrote:
> Is the Windows Firewall turned OFF? The Windows Firewall is bound to 
> the IP address of the connector: when the IP address changes 
> incorrectly the firewall will block traffic with the wrong IP address 
> ("Failed to renew DHCP IP").
>
> If the DHCP IP renew doesn't work correctly the routing will fail.
>
> (david)
>

The firewall is disabled for the Tap-Win32 adapter. I have now tried
disabling the Win7 firewall completely.  I still receive these
occasionally:

--
Mon Mar 07 19:15:12 2011 WARNING: Failed to renew DHCP IP address lease on
TAP-Win32 adapter: The name specified in the network control block (NCB) is
in use on a remote adapter.  The NCB is the data.
(code=5322)
Mon Mar 07 19:15:12 2011 TEST ROUTES: 0/0 succeeded len=0 ret=0 a=0 u/d=down
Mon Mar 07 19:15:12 2011 Route: Waiting for TUN/TAP interface to come up...
Mon Mar 07 19:15:13 2011 TEST ROUTES: 0/0 succeeded len=0 ret=0 a=0 u/d=down
Mon Mar 07 19:15:13 2011 Route: Waiting for TUN/TAP interface to come up...
Mon Mar 07 19:15:15 2011 TEST ROUTES: 0/0 succeeded len=0 ret=0 a=0 u/d=down
Mon Mar 07 19:15:15 2011 Route: Waiting for TUN/TAP interface to come up...
Mon Mar 07 19:15:16 2011 TEST ROUTES: 0/0 succeeded len=0 ret=0 a=0 u/d=down
Mon Mar 07 19:15:16 2011 Route: Waiting for TUN/TAP interface to come up...
Mon Mar 07 19:15:17 2011 TEST ROUTES: 0/0 succeeded len=0 ret=0 a=0 u/d=down
Mon Mar 07 19:15:17 2011 Route: Waiting for TUN/TAP interface to come up...
Mon Mar 07 19:15:18 2011 TEST ROUTES: 0/0 succeeded len=0 ret=0 a=0 u/d=down
Mon Mar 07 19:15:18 2011 Route: Waiting for TUN/TAP interface to come up...
Mon Mar 07 19:15:19 2011 TEST ROUTES: 0/0 succeeded len=0 ret=0 a=0 u/d=down
Mon Mar 07 19:15:19 2011 Route: Waiting for TUN/TAP interface to come up...
Mon Mar 07 19:15:21 2011 TEST ROUTES: 0/0 succeeded len=0 ret=0 a=0 u/d=down
Mon Mar 07 19:15:21 2011 Route: Waiting for TUN/TAP interface to come up...
Mon Mar 07 19:15:22 2011 TEST ROUTES: 0/0 succeeded len=0 ret=0 a=0 u/d=down
Mon Mar 07 19:15:22 2011 Route: Waiting for TUN/TAP interface to come up...
Mon Mar 07 19:15:23 2011 TEST ROUTES: 0/0 succeeded len=0 ret=0 a=0 u/d=down
Mon Mar 07 19:15:23 2011 Route: Waiting for TUN/TAP interface to come up...
Mon Mar 07 19:15:24 2011 TEST ROUTES: 0/0 succeeded len=0 ret=0 a=0 u/d=down
Mon Mar 07 19:15:24 2011 Route: Waiting for TUN/TAP interface to come up...
Mon Mar 07 19:15:25 2011 TEST ROUTES: 0/0 succeeded len=0 ret=0 a=0 u/d=down
Mon Mar 07 19:15:25 2011 Route: Waiting for TUN/TAP interface to come up...
Mon Mar 07 19:15:27 2011 TEST ROUTES: 0/0 succeeded len=0 ret=0 a=0 u/d=down
Mon Mar 07 19:15:27 2011 Route: Waiting for TUN/TAP interface to come up...
Mon Mar 07 19:15:28 2011 TEST ROUTES: 1/1 succeeded len=0 ret=1 a=0 u/d=up

or

Mon Mar 07 19:23:14 2011 WARNING: Failed to renew DHCP IP address lease on
TAP-Win32 adapter: The system cannot find the file specified.
  (code=2)
Mon Mar 07 19:23:14 2011 TEST ROUTES: 1/1 succeeded len=0 ret=1 a=0 u/d=up
--

but as you can see, the TAP-Win32 adapter eventually works.

I am not seeing a relationship between the DHCP Warnings and the occasional
Tap-Win32 adapter failures since the DHCP warnings occur during successes as
well.

I can't cause a reliable failure with the TAP-Win32 adapter, and since I
don't understand why it sometimes is immediate, sometimes requires a longer
"Waiting for TUN/TAP interface.." loop and sometimes doesn't ever come up
within the route-delay period I'm not able to narrow things down (I wonder
why openvpn-gui would ever present the connection as being successful if the
Tap-Win32 adapter has obviously failed ("TEST ROUTES" never has a ret=1) and
doesn't have a proper
IP?)


> Arthur Murray wrote:
>> I have tried "route-method exe", I have tried disabling the TAP-Win32 
>> adapter from the Win7 firewall, and I have tried setting the 
>> Tap-Win32 adapter properties to "always active" but none of these 
>> solve the problem.

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