Really interesting. Dhcp optional routes overriding VPN tunnel routing rules.
this post was submitted on 07 May 2024
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Dang option 121.
I told him 120 options was enough, but he just had to keep adding options.
120 options should be enough for anyone.
119 is too few and 121 is too many.
120 options is too many, we should make standard that works for everyone
Any vpn solution that uses a TCP/IP shim in full tunnel mode will ignore option 121 or any other routing options (static routes, etc). Most corporate VPNs like Global Protect/Cisco Any Connect, Appgate, etc will enforce full-tunnel. Any user who is using a VPN for privacy reasons should also use a full tunnel as well especially when connecting to an untrusted networks.
Why doesn't my internet look like that stock image tunnel of 1 and 0?
Skill issue
Linux and android unaffected, go figure. Anyway..
Not quite what the article says:
When apps run on Linux there’s a setting that minimizes the effects, but even then TunnelVision can be used to exploit a side channel that can be used to de-anonymize destination traffic and perform targeted denial-of-service attacks. Network firewalls can also be configured to deny inbound and outbound traffic to and from the physical interface. This remedy is problematic for two reasons: (1) a VPN user connecting to an untrusted network has no ability to control the firewall and (2) it opens the same side channel present with the Linux mitigation.
It only works if you have split tunnel setup, which I don't think anybody does for commercial privacy VPNs
Do you mean the attack only works against people with a split tunnel setup?
Yes
The researchers believe it affects all VPN applications when they’re connected to a hostile network and that there are no ways to prevent such attacks except when the user's VPN runs on Linux or Android.
So presumably, home networks are safe, and you can also protect yourself out and about by hotspotting off of your android rather than connecting to a dodgy cafe wifi?
Yes, that's suggested at the end of the article. Another workaround, they say, is to run your VPN connection from inside a virtual machine whose network interface is not in bridged mode.
How did nobody discover this sooner if it is a common network option? This seems like it should have been well known to professionals. Who dropped the ball?
Your vpn should be running on a middlebox and have firewall rules to prevent leaks.