Typically, when you try to access a website on the Internet, your ISP (Internet Service Provider) receives the request and redirects you to your destination. As your Internet traffic passes through your ISP, they can see everything you do online. What’s more, they can track your behavior and sometimes even hand your browsing history over to advertisers, government agencies and other third parties.

A number of vendors that sell dial-up access servers have implemented the ability to create a tunnel on behalf of a dial-up client. The computer or network device providing the tunnel for the client computer is variously known as a Front End Processor (FEP) for PPTP or an L2TP Access Concentrator (LAC) for L2TP. For the purposes of this reference, the term FEP is used to describe this functionality, regardless of the tunneling protocol. To carry out its function, the FEP must have the appropriate tunneling protocol installed and must be capable of establishing the tunnel when the client computer connects.
Challenge Handshake Authentication Protocol (CHAP) is an encrypted authentication mechanism that prevents transmission of the actual password on the connection. The NAS sends a challenge, which consists of a session ID and an arbitrary challenge string, to the remote client. The remote client must use the MD5 one-way hashing algorithm to return the user name and a hash of the challenge, session ID, and the client’s password. The user name is sent as plain text.

Because it is impossible to update separate user accounts on separate servers for the same user simultaneously, most administrators set up a master account database at a domain controller or on a RADIUS server. This enables the VPN server to send the authentication credentials to a central authenticating device, and the same user account can be used for both dial-up remote access and VPN-based remote access.
Are you so used to your data traveling over Wi-Fi that you've stopped worrying about the security of that data—and about who else might be spying on it, or even stealing it for nefarious purposes? If so, you are—sadly—in the majority, and you ought to consider using a viritual private network, or VPN. In fact, when PCMag conducted a survey on VPN usage, we found that a dismal 71 percent of the 1,000 respondents had never used a VPN. Even among those who support net neutrality—who you might think would tend to be well informed on technology and privacy issues—only 45 percent had used a VPN.