tun interface not working in ubuntu14.4?

Question

I have problem making the tun interface on Ubuntu 14.04 work correctly. The commands

lsmod | grep tun

and

sudo modprobe tun 

return nothing. Even the module, tun.ko.gz in /lib/modules/ and elsewhere can not be found. Yet I have created a tun interface with the following command BUT THE INTERFACE IS NOT OPERATIONAL (i.e. RUNNING) even using the "sudo ip link set dev tun2 up" command.

openvpn --mktun --dev tun2

the interface shows up in ifconfig

tun2      Link encap:UNSPEC  HWaddr   00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00  
  inet addr:10.0.0.1  P-t-P:10.0.0.1  Mask:255.255.255.0
  UP POINTOPOINT NOARP MULTICAST  MTU:1500  Metric:1
  RX packets:0 errors:0 dropped:0 overruns:0 frame:0
  TX packets:0 errors:0 dropped:0 overruns:0 carrier:0
  collisions:0 txqueuelen:100 
  RX bytes:0 (0.0 B)  TX bytes:0 (0.0 B)

HOW CAN I FORCE THE TUN INTERFACE TO RUNNING STATE? DOES MY SYSTEM SOPPERT THE TUN MODULE? Why doesn't it show up in the lsmod cmd?

Answer 1

The problem is easily solved. As soon as I attached a process to the interface it becomes running. By attaching a process I mean running the "software" e.g. simpletun.c in the following link. http://backreference.org/2010/03/26/tuntap-interface-tutorial/ After running the code above, the interface changed its status to running and data sent over it would show up in tcpdump. Hope this answer would help others.