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

Error: -bash: mail: command not found in CentOS

You may get this error while trying to send mail from ssh. It means the package is not installed. Try to send mail after installing the package " mailx"


[root@test ~]# mail -v testmail@example.com

-bash: mail: command not found


Fix: # yum install mailx