Some VPN providers leak your IPv6 IP address

August 10, 2018

Just a short note. Today a friend called me if I could help him to get TV streaming from TV stations in the US running. When I looked at it, he even selected a VPN provider which offers servers in the US to circumvent the Geo restrictions, but still it didn’t work. He showed me the NBC website where the first ad was shown and than the screen stayed black. Having no experience with VPN providers and TV streaming sites I first checked the openvpn configuration and made sure that the routing table was correct (sending all non local traffic to the VPN). Looked good, so I opened the developer tools in the browser and saw following repeating.

 

Searching the Internet did not provide an answer … than I just tried to download the file with wget and I got following:

$ wget http://nbchls-prod.nbcuni.com/tve-adstitch/4421/xxxx-1.ts
--2018-08-10 19:20:20-- http://nbchls-prod.nbcuni.com/tve-adstitch/4421/xxxx-1.ts
Resolving nbchls-prod.nbcuni.com (nbchls-prod.nbcuni.com)... 2600:1406:c800:495::308, 2600:1406:c800:486::308, 104.96.129.98
Connecting to nbchls-prod.nbcuni.com (nbchls-prod.nbcuni.com)|2600:1406:c800:495::308|:80... connected.
HTTP request sent, awaiting response... 403 Forbidden
2018-08-10 xx:xx:xx ERROR 403: Forbidden.

Seeing this it hit me … its using IPv6 … so I did a fast check with

% wget -4 http://nbchls-prod.nbcuni.com/tve-adstitch/4421/xxxx-1.ts
--2018-08-10 19:20:30-- http://nbchls-prod.nbcuni.com/tve-adstitch/4421/xxxx-1.ts
Resolving nbchls-prod.nbcuni.com (nbchls-prod.nbcuni.com)... 104.96.129.98
Connecting to nbchls-prod.nbcuni.com (nbchls-prod.nbcuni.com)|104.96.129.98|:80... connected.
HTTP request sent, awaiting response... 200 OK
Length: 242520 (237K)

So with a IPv4 request it worked. His VPN provider was leaking the IPv6 traffic to the Internet – that is potentially a security/privacy problem as many use a VPN provider to hide them! So make sure to check before relying on the VPN security/privacy.