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max2

macrumors 603
Original poster
May 31, 2015
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Is it possible a coffee shop can disable or prevent VPNs from connecting to it?

WiFi works without VPN otherwise
 
It is possible. I've been to hotels that have pulled nonsense like that before. The usual ways they do it are:
  • Blocking specific outgoing ports used by your VPN (by far the most common way)
  • If they provide DNS via DHCP, they can block requests to your VPN's hostnames
  • Detect and prevent packets with security handshakes - which would essentially stop you from have a secure connection anywhere.
Why they do it, I dunno. But it is technically possible.
 
It is possible. I've been to hotels that have pulled nonsense like that before. The usual ways they do it are:
  • Blocking specific outgoing ports used by your VPN (by far the most common way)
  • If they provide DNS via DHCP, they can block requests to your VPN's hostnames
  • Detect and prevent packets with security handshakes - which would essentially stop you from have a secure connection anywhere.
Why they do it, I dunno. But it is technically possible.

Thanks anyway around it?
 
A lot of VPNs will use standard internet ports - most likely 443 for a secure connection (there may be some UDP ports required too). Coffee shops will have 443 open otherwise you couldn't hit a secure website (but they could block it in other ways as described above)

Not every VPN uses these ports though so if the coffee shop has blocked other ports then you might have problems. I know one free VPN product I've used before didn't use port 443 (there was a paid-for version of the product that enabled that. ofc.)
 
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