When I am connecting to a public wi-fi (in a hotel or airport for example) I am using VPN to increase my security. But right after I join the network some applications start to establish connections (email or IM) before I even click Connect in my VPN app.

Is there an application that could allow only one application (VPN app) to send/receive data and block others before I establish a VPN connection? It would need to have some "Safe mode" that would allow an entire traffic so that I could use it when I am at home or just don't want to use a VPN.

I am interested both in Windows and Mac but any recommendation is helpful. I am using NordVPN if that matters.

  • 2
    I think that's something integrated into VPN clients themselves, because they accomplish that by taking sole ownership of the connection. I believe TunnelBear does this, so you could always switch to that.
    – Keegs
    Jul 3, 2018 at 14:21
  • Nord also has some setting like it, a Kill-Switch, nordvpn.com/features/kill-switch-technique Jul 4, 2018 at 10:10
  • Kill-Switch is a different feature. It let's you to kill some apps (like torrent downloading) after you disconnect from VPN. But other (not killed) apps still have internet access.
    – bpiec
    Jul 4, 2018 at 10:27
  • 1
    Pretty much any firewall out there is capable of this, even the rudimentary Windows built-in firewall. Just put a rule that only allows the VPN client network access (either by program or by destination IP), block everything else and you're done.
    – Alejandro
    Jul 10, 2018 at 15:18

2 Answers 2


All that you have to do is activate NordVPN's kill switch ...

From How to enable the NordVPN kill switch :

A kill switch is a VPN feature that helps protect your sensitive data in case your VPN connection goes down. In this event, it safeguards your IP address and online activity from being exposed, thus preserving your anonymity and security on the internet, meaning a kill switch is a necessary part of any VPN experience.

NordVPN desktop apps for Windows and macOS let you specify which applications can be shut down if the VPN connection drops. This is called an app kill switch and it prevents applications from sending unprotected traffic to the web, and keeps your data safe from being exposed to online threats. The desktop software also has an internet kill switch feature, which can terminate the net connection on the system level instead of shutting down individual apps

Btw, although that describes connection loss, with kill switch active, nothing will be sent to the internet at start-up until the VPN Connects.

Hope that helps


On Windows you can use Connection blocker feature in NetLimiter.
I prefer it to using Windows Firewall because you can just setup it and forget, also it's quite straightforward to setup and enable/disable.
Downsides: it's proprietary and costs at least 24.95$ =|

Here's how to setup it if you use openvpn. You may need to add more complex rules in case if allowing only openvpn.exe isn't enough for your vpn software. To allow all traffic just untick "Blocker On" enter image description here

Source: https://www.reddit.com/r/VPN/comments/8upjeb/found_out_incredibly_simple_rule_set_for_kill/

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