What is a VPN Virtual Private Network?

What is a VPN?

Let's start with a bit of history. Back in the old days, you used to buy Leased Lines or Private Circuits from phone companies. Typically it would have been something called a T1 (for voice) or DS1 (for data) 1.5Mb/s. You would have one end of this circuit start at your main office, and the other end stop at your remote office. This would give you a "private network". Nobody else could use those T1/DS1 resources. Another term used was Point-to-point circuits.

Jump to today. Broadband internet circuits are in, and for a lot cheaper than the dedicated circuits above. Companies such as Cox, Comcast, Verizon, Centurylink, etc.

That's great, but this type of circuit is NOT private and open to the internet and the billions of people on it. Both good and bad people.

That's where a VPN comes in - it's not a Private Network as in the past, it's a Virtual Private Network. It uses the Broadband Internet, but used an encrypted "Tunnel" to create a logical connection from your Home office to your Remote office.

So if you want private company information to pass between the Home and Remote offices, you would use the VPN, and if its regular old internet traffic such as Facebook, that would go unencrypted and NOT thru the VPN tunnel. Controlling what traffic goes to the VPN and what does not is the function of a Router.

VPN's can be setup as Site-to-Site, where the VPN tunnel stays up all the time, and if the broadband circuit goes down, the VPN does also, and when it comes back up, so does the VPN. They can also be setup as user-to-site VPN's typically used just for remote users on their laptops or when they are at home, and still need access to private company information.