A virtual private network (VPN) protects the confidentiality of data as it traverses your network. VPN’s core is encryption, although it also uses authentication. There are three encryption options for a VPN, especially for the applications users have on their laptops or phones to connect to the office remotely. The three options are IPSec, SSL/TLS, and SSH. These three encryption protocols are used for other applications as well.
IPSec is an encryption protocol that can be used in about any scenario since it works at layer 3 of the Open System Interconnect (OSI) model from the International Standards Organization (ISO). Layer 3 is the network layer that gets data, voice, or video to its correct network destination. So, if you add IPSec, it will get your data to its destination in an encrypted and confidential format. A common use other than VPNs is for site-to-site connectivity between business locations.
Transport Layer Security (TLS) is the upgrade to SSL. It would have been called SSL 4.0 if its ownership had not transferred from Netscape to the International Engineering Task Force (IETF) in 1999. TLS provides an encryption option for VPNs, but also for any web-based connection. These connections could be a browser-based connection to a bank, Amazon, or any other site that has a lock in the corner of your browser.
Secure Shell (SSH) is primarily used for remote connections from one computer to another. It has commonly been used by network administrators to connect to servers, routers, and switches for administrative purposes. These connections are for configuration and monitoring.