What are Transport Level Virtual Private Networks 


In this article we are going to explain what transport level virtual private networks are and what technologies they implement.

Level 4 Virtual Private Networks (Transport) are implemented through the Secure Sockets Layer (SSL) protocol (in this category is also included in the SOCKS Protocol, which will not be analysed here). The following describes SSL VPN technology, safety mechanisms are analysed and indicative applications.

SSL General Description

Application Level Virtual Private Networks (VPNs) use the Secure Sockets Layer (SSL) protocol to implement communications through insecure Internet channels; safeguarding a certain level of security. In fact, an SSL VPN provides end-users with authorized and secure access to applications such as HTTP, client/server and file sharing.

SSL is familiar to most users, yet and those without a particular background in technical knowledge. It’s already installed on any computer connected to the Internet and uses a standard browser without any particular setting. SSL is independent of the operating system and allows for an escalation in the control of access to applications, making it ideal for “mobile” users who wish to have access from an “unsafe” endpoint.

SSL can provide access control to extranet VPNs or remote access VPNs. Also the user,  via an SSL VPN, has access to Web applications from anywhere by simply using a Web browser, a single Internet connection, and without the need for any particular software in the computer. SSL VPNs can “pass” over firewalls and address NAT (Network Address) issues Translation), issues that are difficult to resolve in the case of IPSec VPNs.

The secure connection provided with SSL achieved through:

  • the certification of the identity of the parties communicating and
  • the encryption of the movement between them.

It is clarified that SSL VPNs are for applications that support SSL protocol, such as Web browsers and Web-based E-mail.


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