In light of the recent TunnelVision vulnerability I wanted to share a simple firewall that I wrote for wireguard VPNs.
https://codeberg.org/xabadak/wg-lockdown
If you use a fancy official VPN client from Mullvad, PIA, etc, you won’t need this since most clients already have a kill switch built in (also called Lockdown Mode in Mullvad). This is if you use a barebones wireguard VPN like me, or if your VPN client has a poorly-designed kill switch (like NordVPN, more info here).
A firewall should mitigate the vulnerability, though it does create a side-channel that can be exploited in extremely unlikely circumstances, so a better solution would be to use network namespaces (more info here). Unfortunately I’m a noob and I couldn’t find any scripts or tools to do it that way.
You’re still right in 99% of all use cases.
Nobody operates VPNs for privacy in split tunnel. So everyone running Linux that would be concerned about this is unaffected.
I thought TunnelVision applies to all VPN users that don’t use firewall / network namespaces
It doesn’t apply to Linux unless you do split tunnel, which no commercial VPN configs use, because it doesn’t make sense to