IPSec is a family of standards designed to securely connect local networks over the Internet. IPSec creates virtual private networks (VPN) for this purpose.

That is why it is compatible with all TCP/IP-based network programs that can handle different networks.

IPSec can connect local networks or individual clients with private network addresses to the Internet by establishing a so-called tunnel. The sender encrypts the IP packets and encapsulates them in new packets. At the recipient's end, the packets are decapsulated, decrypted, verified, and forwarded.

However, before an encrypted connection can be established, both parties must be certain that the other party is who they claim to be (authentication). Two methods are commonly used for this purpose. One is called a pre-shared key (PSK) or shared secret. In this case, both parties know a common password. The other method uses what is known as public-key cryptography.