The full English name of VPN is "Virtual Private Network", which means "virtual private network". Its essence is a special encrypted communication protocol that can establish a dedicated communication line between corporate intranets in different locations, just like a real dedicated line, but without the need for real physical lines. Therefore, it is like applying for a dedicated line at the telecommunications bureau, but without paying the cost of laying the line or purchasing hardware equipment. VPN can help remote users, company branches, partners and suppliers securely connect to corporate internal networks. It is a stable, safe and reliable encrypted tunnel that can pass through chaotic public networks. A virtual private network is an extension of an enterprise's intranet, rather than an independent network.
When a remote terminal accesses the corporate intranet through VPN, its identity will be verified once. Once the identity is authenticated, the remote terminal will obtain an intranet IP address and generate a default route. All traffic connected through the VPN will be forwarded to the VPN gateway on the corporate intranet through the encrypted tunnel, and then forwarded by the VPN gateway to the corresponding intranet IP address. Since the VPN only authenticates the identity once, the remote terminal can freely access all resources in the intranet without having to authenticate again.
