How can I force a tap/tun interface into the running state?

Question

I am trying to capture packets on a tun interface with libpcap. I am creating the interface with:

openvpn --mktun --dev tun0

When the adapter is setup it appears as so when I run ifconfig:

tun0      Link encap:UNSPEC  HWaddr 00-00-00-00-00-00-00-00-00-00-00-00-00-00-00-00
          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)

The adapter needs to be running in order for libpcap to detect the packets:

POINTOPOINT NOARP RUNNING MULTICAST  MTU:1500  Metric:1

Is there any way to force the tun interface to be running so I can capture packets on it?

Answer 1

If by running you mean "up", the command is:

ip link set dev tun0 up