Connect ONLY via VPN

How can I create connection via VPN by default when Ubuntu loading? Also I need don't reach Internet if VPN connection not established or disconnected.

In few words, I need connection to Internet ONLY via VPN.

this is what I have right now, in some time I'll make a script to make all this automatic in the startup, but meanwhile I hope it works for you.

I'm assuming you are using OpenVPN if you are not you'll have to get the idea and then translate it to your VPN program.

First you need to go to /etc/openvpn and make a file called VPNconfig with two lines (with your real values)

VPN_User
VPN_Password

Now for all your .ovpn files in /etc/openvpn you should replace

auth-user-pass

with

auth-user-pass VPNconfig.txt VPNconfig.txt

That will make sure that you don't have to write user and password each time you log in (it's also highly insecure so beware of what password you use for your VPN, make it sure it's not you password for everything else)

Now I'll make an alias in /root/.bashrc

alias vpn='cd /etc/openvpn/ && openvpn /etc/openvpn/Your_VPN_Ovpn_File.ovpn'

So when you startup you just open a terminal and run

sudo su
vpn

To make sure your IP doesn't get revealed when the VPN disconnects you should use an iptables script, you know it follow the steps specified here, specially check the answer of windom at the bottom of the first page. If you use other VPN than PIA you will have to modify the script to fetch your IP ranges.

That script generates the two files specified in the first post iptables-vpn and iptables-novpn.

You would also like to avoid DNS leaks, for that append at the start of each .ovpn

up /etc/openvpn/update-resolv-conf
down /etc/openvpn/update-resolv-conf
--script-security 2

and check if it worked here

So as gertvdijk has said you need the connection to access the VPN, so the order would be, connect to VPN, then execute ./iptables-vpn and now you will be secure of VPN disconnections, the problem is that if it disconnects you will have to manually set it up executing ./iptables-novpn , reset the VPN connection, and then turn back on the iptables-vpn.

There is a quicker way with a python script using netifaces but I'm still using this... Hope it helped!

Connect to VPN by default:

Click on Network Manager icon in the system tray and select "Edit Connections...".

Choose your default connection and click the "Edit" button.

In the General tab there is a setting "Automatically connect to VPN when using this connection", select your VPN.

Connect to internet only via VPN:

This can be achieved using a firewall, for an example using UFW (Uncomplicated Firewall) see UFW for OpenVPN.