VPN blocking is a technique to block the secured tunneling communications methods used by VPN. This technique is used by big companies or network administrators. For example, the China tries to block all VPNs in the country by using The Gread Firewall of China.
There are two major ways to block VPN traffic:
Network administrator or firewall tools blocks the ports that are used by common VPN tunneling protocols, such as PPTP or L2TP. Layer Two Tunneling Protocol (L2TP) is usually using TCP port 1701. Point-to-Point Tunneling Protocol (PPTP) is usually using TCP port 1723 and IP port 47 Generic Routing Encapsulation (GRE). Internet Protocol Security (IPSec) uses IP protocol 50, 51 and UDP ports 500, 4500 and other. Sometimes, firewall tools may block a wide range of ports.
Fortunately, they don’t block HTTP port like 80, HTTPs port like 443 and DNS port like 53 because those ports are required ports to browse the internet. If network administrator blocks the listed ports, user can’t visit any website on the web. So, if you use powerful VPN client supporting ports 80, 443 and 53 – you are able to browse Internet with no restrictions.
Some websites and services started to block visitors who access the websites through an IP-address that’s linked to a VPN services. The idea is to blacklist the IP-range of all major VPN services (in spite of the fact that VPN - is a legal service - according to law)
In this case, a simple recommendation is using a VPN service with many servers in different locations. Paid VPN services support the hundreds of locations and the tons of IP addresses all over the internet.
The biggest VPN service available for many locations all over the internet is Trust.Zone VPN. Trust.Zone VPN service supports all 3 primary protocols – PPTP, L2TP and SSTP. Besides that, if your network administrator blocks the major VPN protocols, Trust.Zone VPN is able to forward traffic through the port 80 (HTTP) or the port 53 (DNS). Those ports are usually not blocked by network administrators or firewalls.
The unique features of Trust.Zone are the full anonymity, no logging, unlimited bandwidth, unlimited speed, availability for all OS and devices and a wide range of the VPN servers in the different locations all over the internet.
So, if your network administrator blocks the standard port, just switch to another port (like 80 or 53) of the Trust.Zone VPN client.