Glossary · VPN & tunneling

VPN kill switch

Also calledvpn kill switchnetwork lockwhat is a kill switch

Definition

A VPN kill switch blocks all device network traffic the moment the VPN tunnel drops — preventing accidental leaks.

Explanation

In depth

Without a kill switch, if your VPN tunnel disconnects mid-session (network hiccup, server restart, congestion), your traffic falls back to routing over the naked network — and destinations see your real IP, ISPs see your real destinations, and any cookies or sessions may leak identity. A kill switch prevents that by blocking all outbound traffic until the tunnel is re-established. Two common types: application-level (only blocks specific apps you designated) and system-level (blocks everything until the VPN reconnects). System-level is the safer default. Kill switches are a VPN feature; web proxies do not need them because there is no tunnel to drop — every request either goes through the proxy or fails visibly in the browser.

See alsoKill switch deep-dive

Related terms

VPNA VPN is a service that routes every network request from your device through an encrypted tunnel to a remote server.VPN tunnelA VPN tunnel is the encrypted connection between your device and a VPN server that carries all your device's network traffic.DNS leakA DNS leak happens when your device sends DNS lookups outside the VPN tunnel — revealing which sites you are visiting even though the traffic itself is encrypted.WebRTC leakA WebRTC leak exposes your real IP to a website via the browser's WebRTC API — even when a VPN is active — because WebRTC uses STUN outside the tunnel.

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