LinuxHostingSupport

TUN module is required to configure VPN (Virtual Private Network) tunneling on a VPS,. The TUN module has to be enabled on the Hardware node as well as on the VPS from the node itself.  Login to your Host server and execute the following command:

First check if the TUN module is enabled on the hardware node:

lsmod | grep tun

If not, load the module using modprobe:

modprobe tun

Now, enable the TUN module on a VPS:

vzctl set VEID --devices c:10:200:rw --save
vzctl exec VEID mkdir -p /dev/net
vzctl exec VEID  mknod /dev/net/tun c 10 200
vzctl exec VEID  chmod 600 /dev/net/tun

where, VEID is the VPS ID you want to enable the TUN module on. Once done, you can configure VPN on the VPS using any available vpn server like OpenVPN.

How to re-create/re-install a OpenVZ VPS?

1) Make a backup of the configuration file:

cp -p /etc/sysconfig/vz-scripts/VEID.conf  /etc/sysconfig/vz-scripts/VEID.conf_old

2) Stop the VPS:

vzctl stop VEID

3) Destroy/Terminate the VPS:

vzctl destroy VEID

4) Create the VPS using the OS templates stored under /vz/template/cache directory:

vzctl recreate VEID –ostemplate os-template-name

5) Copy the original configuration file back to have the original parameters:

cp -p /etc/sysconfig/vz-scripts/VEID.conf_old /etc/sysconfig/vz-scripts/VEID.conf

6) Start the VPS and reset the password

vzctl start VEID
vzctl set VEID –userpasswd root:password –save

If you receive the error message “vzquota : (error) Quota is running, stop it first” while restarting a VPS, you will first have to turn off it’s quota and then drop it

vzquota off  VEID
vzquota drop VEID

Once done, restart the VPS and it will re-initialize the quota for the VPS and will start the VPS. If the problem persist, remove the /var/vzquota/quota.veid file

rm -f /var/vzquota/quota.veid

and then start the VPS. This should also display the correct disk space used by the VPS.

You see a message “Unable to fork: Cannot allocate memory” while logging to a VPS from the host server. The reason is the VPS is running out of resources especially RAM. To temporary solve the issue, you may restart the VPS by executing

vzctl restart VEID

OR increase RAM for the VPS by increasing privvmpages and kmemsize for the VPS.

Edit the configuration file of the VPS

vi /etc/sysconfig/vz-scripts/veid.conf

increase the value of the above two parameters and restart the VPS.

If you wish to add additional RAM on a Xen based VPS, you need to follow the below steps:

#Search the VM name:

xm list

#Edit the VM’s configuration file. Update the required value and save the file:

vi /home/xen/vmname/vmname.cfg

#To stop and start the VPS, follow the below steps:

xm destroy vmname
xm create /home/xen/vmname/vmname.cfg

#Once the VM is rebooted, login to the console of the VPS and check the allotted RAM:

xm console vmname.vm
free -m

Hope this helps.