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Joined 1 year ago
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Cake day: August 8th, 2023

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  • You aren’t wrong, per se, I think you just don’t fully grasp the attack vector. This is related to DHCP option 121, which allows routes to be fed to the client when issuing the ip address required for VPN connectivity. Using this option, they can send you a preferred default route as part of the DHCP response that causes the client to route traffic out of the tunnel without them knowing.

    E. It would likely only be select traffic routing out of the tunnel. I could, for example, send you routes so that all traffic destined for Chase Bank ip addresses comes back to me instead of traversing the tunnel. Much harder to detect.






  • It probably has to do with being native ipv6 and needing to ride a 6to4 nat to reach the broader internet.

    Start at 1400 and walk the MTU down by ~50 until you find stability, then id creep it back up by 10 to find the ‘perfect’ size, but that part isn’t really needed if you’re impatient. :)

    E. I found 1290 was needed for reliable VPN over an ATT nighthawk hotspot.










  • You are absolutely correct, I should have lead with that. Encrypted client handshake means no one can see what certificate you are trying to request from the remote end of your connection, even your ISP.

    However, It's worth noting though that if I am your ISP and I see you connecting to say public IP 8.8.8.8 over https (443) I don't need to see the SNI flag to know you're accessing something at Google.

    First, I have a list of IP addresses of known blocked sites, I will just drop any traffic destined to that address, no other magic needed.

    Second, if you target an IP that isn't blocked outright, and I can't see your SNI flag, I can still try to reverse lookup the IP myself and perform a block on your connection if the returned record matches a restricted pattern, say google.com.

    VPN gets around all of these problems, provided you egress somewhere less restrictive.

    Hope that helps clarify.