require-vpn

FireFox plugin to require an existing VPN connection before accessing specified hosts.

Install from Mozilla's official MarketPlace: https://addons.mozilla.org/addon/require-vpn

Example

Let's say you have a website with a sensitive data (your bank account, work project, password store, etc) that you don't want to accidentally access with an untrusted network.

This used to happen quite often with my frequent bussiness trips:

I have some existing open tabs with my private data
Then I connect to a public wifi on a train or in a bar
My data could have been leaked
Then I remember that I have to activate my VPN :)

To fight this problem you can use require-vpn plugin. Here's how it works:

It creates a request about your current IP to some IP_CHECKER_URL
If your IP matches your VPN_IP, you are good to go and visit BLOCKED_HOSTS
If not, you would be redirected to PROXY_URI (or if it is not available, the request won't make it to the original server and will be just blocked)

Configuration

VPN_IP - your VPN IP, which is expected
BLOCKED_HOSTS - a new-line separated list with hostnames of blocked resources, default: ['example.com']
IP_CHECKER_URL - a URL to any service that will receive a GET request and return your API in plain text, default: http://icanhazip.com
PROXY_URI - a URI for your proxy server to where a redirect will be made, see here what formats are supported, default: http://localhost:63555