Why software kill switches fail during reconnects, and how system-level firewall filtering prevents exposed IP packets.
Need an outbound block that stays enforced at the OS level even while changing servers or waking from sleep?
If you typed this into a search box, you probably did not do it out of casual curiosity.
Something broke. Maybe a browser tab suddenly showed your local ISP location while you thought the tunnel was up. Maybe an API script threw an authorization error because a request slipped through on your bare domestic IP. Or maybe you had a network dip, watched the app spinner circle while reconnecting, and realized that for three or four seconds, your traffic went straight out unencrypted.
That split second is all it takes. Once an IP mismatch gets logged on a strict remote system, it does not matter if the VPN came back up five seconds later. The record is already there.
The frustration is usually doubled because, on paper, you had the kill switch turned on. The toggle was active, the setting was checked, and the dashboard said you were protected. So how did real packets leak out?
To fix this, you have to look past marketing claims and understand the technical difference between an app-level kill switch and a system-level firewall kill switch.
### The Timing Problem of an App-Based Kill Switch
Most commercial consumer VPNs, including Surfshark, run their core kill switch logic within the client application or via virtual network adapter hooks. Under ideal laboratory conditions, it works fine: you click disconnect, and the client tears down the route cleanly.
The real world is not ideal. Laptops close and go to sleep. Wi-Fi channels get congested and briefly drop packets. Routers renegotiate DHCP leases. Your operating system switches from a 5GHz band to 2.4GHz, or handshakes with an office access point.
When that happens, the VPN tunnel collapses before the application knows it collapsed.
In that microscopic gap—between the moment the encrypted virtual tunnel adapter drops and the moment the software process realizes it needs to rewrite your routing table—your operating system still wants to send internet traffic. Operating systems are fundamentally built to preserve connectivity at all costs. If the virtual gateway disappears, Windows, macOS, and Linux will immediately attempt to fall back to the default physical gateway: your home router, using your raw, unencrypted public IP.
If your VPN client takes even 800 milliseconds to detect the broken socket, execute its script, and flush the routes, any active background connection has already sent raw packets out through your home network.
That is why software kill switches feel like they randomly "lag." They are reactive. They wait for an event, process it, and then try to shut the door. If the door was already open when the wind blew, the papers are already outside.
### What Actually Prevents Outbound Leaks
If you cannot afford a single packet leak, you cannot rely on an app that watches and reacts. You have to rely on proactive firewall filtering at the operating system kernel level.
In a strict firewall setup (often referred to as an "always-on kill switch" or persistent firewall rules):
1. The firewall does not wait for a tunnel failure notification.
1. The default outbound policy for the entire machine is set to DROP or BLOCK.
1. Only two explicit exceptions are permitted: local loopback communication, and outbound packets directed exclusively to the IP address of the active VPN server on its specific tunnel port.
1. All other traffic must route through the virtual VPN interface.
Under this architecture, what happens when your Wi-Fi flickers or the server handoff occurs?
Nothing leaks. Because even if the tunnel completely dies, the underlying operating system firewall is still enforcing the rule: *block all traffic not destined for the VPN server's handshake port.* The operating system cannot fall back to your physical gateway for general web traffic, because the firewall outright drops any unencrypted request heading to an arbitrary web server. Your internet simply freezes solid until the tunnel is re-established.
It is a silent, stubborn wall. It does not depend on a background desktop app running without a crash.
### Where ONLYDOGSVPN Fits In
This brings us to ONLYDOGSVPN.
We do not pitch ONLYDOGSVPN as a generic consumer entertainment tool loaded with dozens of gimmicks you will never open. If your primary goal is finding fifty different virtual locations to browse streaming catalogs from random countries, or you want a super-flashy interface with widgets, this is probably not what you want. You would be better off sticking with mass-market consumer options.
ONLYDOGSVPN was put together for people who treat network boundaries as strict infrastructure.
Instead of relying solely on reactive client-side scripts, ONLYDOGSVPN utilizes persistent, system-level firewall rules (such as WFP on Windows and native packet filters on Unix-based systems). When the kill switch is engaged, it locks the networking stack. If your internet connection drops, if your machine wakes abruptly from sleep mode, or if you intentionally bounce between server endpoints, your true IP does not get a split-second window to resolve outside the tunnel.
If the encrypted path is absent, traffic stops. Zero outbound clearance.
### Who Should Not Choose This Approach
A strict firewall kill switch is not for everyone, and it helps to be completely clear about the trade-offs:
- **It can be unforgiving with public captive portals:** If you frequently connect to hotel or airport Wi-Fi networks that require you to accept terms in a web browser before getting access, an aggressive firewall kill switch will block that login page until you temporarily toggle it off or whitelist the local gateway.
- **No graceful degradation:** Some users prefer their internet to "just keep working" if a VPN server stalls. With a true packet-blocking kill switch, your connectivity will simply cut off entirely. You have to accept downtime over data leakage.
- **Fewer consumer bells and whistles:** If your priority is dedicated streaming optimization for regional TV channels, consumer-heavy brands invest more engineering into bypassing entertainment geo-blocks on smart TVs.
If you understand those trade-offs and your core priority is operational security—knowing that a momentary Wi-Fi hiccup will never silently expose your real location to an active service—the difference between reactive software routing and kernel-level firewall enforcement is absolute.
### Testing Your Existing Setup
Before changing anything, you can test whatever tool you currently use:
1. Open a terminal and run a continuous ping to a public resolver or an address check endpoint.
1. Ensure your current VPN and kill switch are active.
1. Instead of cleanly disconnecting inside the app, simulate a real failure: pull your Ethernet cable, briefly toggle airplane mode, or kill the core VPN background process through Task Manager or Activity Monitor.
1. Restore the interface or watch the reconnect phase closely.
If you see even one ping reply resolve through your local ISP gateway or your real IP show up in an automated request before the tunnel finishes rebuilding, your switch is software-reactive.
When you need that boundary to hold unconditionally, configure a system that blocks by default, rather than one that scrambles to react after the link drops.