Hello!



Hope we are not too late .
We jist tested block-local using this client in Windows 10 Pro 22H2

and do not see any difference in behaviour comparing with 2.6.

Thank you!




06.06.2024 16:23, Gert Doering пишет:
Hi,

we have new code in master that helps with the "TunnelCrack" and
"TunnelVision" attacks, that is, packets intended to go into the
VPN being leaked away by means of a malicious DHCP server (= routing
points outside the tunnel, so packets never hit OpenVPN).

We used to have

   block-outside-dns

to prevent Windows from doing DNS lookups "around the VPN" - the main
intent of this was "make sure split DNS works", but a side effect has
also been "avoid DNS leaks".

Heiko has now extended this code to be able to "block everything not
going into the VPN".  To activate this, you need

   redirect-gateway def1 block-local

in your config ("block-local" is the keyword, but without "def1" you
end up with a split-tunnel and "nothing else is allowed", which is rarely
a really good combination).

Repeat: if "redirect-gateway block-local" is active, NO packets leave
via LAN/WiFi/... interfaces, except those sourced by the openvpn.exe
process.  This is important for maximum privacy, especially if you
roam into a network with an untrusted DHCP server.


Now - this code has been merged into "git master", and installers
are here:

https://github.com/OpenVPN/openvpn-build/actions/runs/9391365526?pr=641

(bottom of the page, "Artifacts", .zip files with a .msi inside).


I want to have this in 2.6 as well, as it's sort of important for certain classes of users (and also VPN providers, offering this as a service) - but
I do not feel it has been tested enough yet.

So: PLEASE test these windows installers, in all 3 variants

  1.  <nothing special in the config>
  2.  block-outside-dns
      (DNS is blocked, everything else not routed into the VPN tunnel - like
      "your local printer" etc - still works)
  3.  redirect-gateway def1 block-local
      (ONLY VPN works)

and report back to us.

gert




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