cannot set TUN interface up/down with Python API (wrapper)

[David Pradas]

Hi,

I'm having a problem when using the Pyhton API (wrapper) for link 
management (change address, set state up/down). I am not able to set a 
TUN interface up/down with the python wrapper. However, I am capable of 
doing that with the "C" API.

This is the procedure I follow:

1. I first create the TUN interface "tun0":

/sudo ip tuntap add dev tun0 mode tun/

2. Then, I execute my python script (test.py):

/#!/usr/bin/env python2//
//import netlink.route.link as link//
//import netlink.core as netlink//
//import netlink.route.address as address//
//
//sock = netlink.Socket()//
//sock.connect(netlink.NETLINK_ROUTE)//
//cache = link.LinkCache()//
//cache.refill(sock)//
//iface = cache['tun0']//
//iface.flags = ['-up']//
/*/iface.change()/*/
/
3. Finally, I obtain the following output when the file "test.py" has 
been executed.

I get an " Invalid input data or parameter" exception when I call the 
"iface.change()" :

//  nl_recvmsgs_report() returns error
//  Traceback (most recent call last):
//  File "./test.py", line 12, in <module>
//    iface.change()
//  File "/usr/local/lib/python2.7/dist-packages/netlink/route/link.py", 
line 409, in change
//    raise netlink.KernelError(ret)
// netlink.core.KernelError: Kernel returned: Invalid input data or 
parameter

On the other hand, I am capable of setting up/down other interfaces 
which are not tun/tap (such as "eth") following the same method. 
However, even in that case, I obtain the following error:

// File "./test.py", line 12, in <module>
//   iface.change()
//  File "/usr/local/lib/python2.7/dist-packages/netlink/route/link.py", 
line 409, in change
//    raise netlink.KernelError(ret)
// netlink.core.KernelError: Kernel returned: Message sequence number 
mismatch

I can not figure out where the problem is. Any ideas please?

I am running Ubuntu 14.04 LTS 64 bits and using the last release of 
libnl 3.2.26 (I have also tried 3.2.25 with same results) . FYI: the 
Python wrapper was correctly working with Ubuntu 12.04 LTS 64 bits, i.e. 
I could set the TUN up/down without problems.

Thank you in advance for your help,

David Pradas