1. point-to-point tunneling protocol (PPTP) 1723?

2. Layer 2 Tunnel Protocol (L2TP) 500?

Among them, PPTP protocol uses 1723 TCP port number, and L2TP protocol uses 500 TCP port number.

1.VPN definition:

The full English name of VPN is "Virtual Private Network", which translates to "Virtual Private Network". As the name implies, a virtual private network can be understood as a virtual internal private line. It can establish a special communication line between two or more intranet connected in different places through a special encrypted communication protocol, just like setting up a special line, but it does not need to really lay physical lines such as optical cables.

It's like applying for a private line in a telecommunications bureau, but laying the line doesn't cost money, and you don't have to buy hardware equipment such as routers. VPN technology used to be one of the important technologies of routers. At present, VPN function is also supported in switches, firewall devices or WINDOWS2000 software. In a word, the core of VPN is to establish a virtual private network by using public network.

2.VPN network protocol:

According to the needs of different users, VPN has three solutions: access VPN, intranet VPN and extranet VPN)(Easy VPN is also called EzVPN). These four types of VPN correspond to the internal network and external network (external extension) composed of traditional remote access network, enterprise network and enterprise network of related partners.