How to Enable TUN/TAP Module in OpenVZ ?

OpenVZ supports VPN inside a container via kernel TUN/TAP module and device. To allow VPS #101 to use the TUN/TAP device the following should be done:

#101 – VPS  id. Replace #101 with your VPS id.

Make sure the tun module has already loaded on the Node.
[root@Node /]#  lsmod | grep tun

If not listed, then load the tun module with the below command
[root@Node /]# modprobe tun

[root@Node /]#  lsmod | grep tun
  tun                    82432  6
Run the following command in Node:

[root@Node /]#  vzctl set 101 –devnodes net/tun:rw –save

[root@Node /]#  vzctl set 101 –devices c:10:200:rw –save

[root@Node /]#  vzctl stop 101

[root@Node /]#  vzctl set 101 –capability net_admin:on –save

[root@Node /]#  vzctl start 101

[root@Node /]#  vzctl exec 101 mkdir -p /dev/net

[root@Node /]#  vzctl exec 101 chmod 600 /dev/net/tun

To check TUN/TAP is enabled or not :

[root@Node /]# vzctl enter 101

Inside the VPS:

[root@vps /]# cat /dev/net/tun

cat: /dev/net/tun: File descriptor in bad state     # It means the TUN/TAP is enabled on your VPS.

cat: /dev/net/tun: No such device     #  If you receive like this, then the TUN/TAP has not enabled on your VPS . Try to enable TUN/TAP again and check.

Source: http://wiki.openvz.org/VPN_via_the_TUN/TAP_device