IP Blocking
Your IP address shares a lot of information about your device and location with the websites you visit. If you‘re using a VPN, websites will see the IP address and location of the server you‘re connected to instead.
Companies like Netflix and Hulu compare their visitors’ IP addresses against a database of known VPN servers, and will block your access to their website if there’s a match. Many VPN providers regularly change their servers’ IP addresses to evade this detection as newer IPs won’t yet be on the blacklist.
Port Blocking
When you use a VPN, your data passes through a number of ports. Network administrators commonly close the ports that are most often used by VPNs so that they cannot access the network.
Deep Packet Inspection (DPI)
Governments and corporations can use DPI techniques to examine the data that travels through their network and act depending on what they find. Using DPI, they can to determine if a VPN is being used and then either block, re-route, or log the data.
