An Introduction to the Types of VPNs
Virtual Private Networks or VPNs have become commonplace for millions of users across
the world in both their personal lives and their workplaces. In essence they allow computers
on separate local networks (LANs) in different locations to connect to each other across the
public connections of the internet without anyone else being able to see or intercept the information
that is travelling between them.
They are ideal and vital for connecting employees who are working on the move, from home
or from satellite office locations as well as private individuals who need to connect with
their home networks when they're out and about. Users can connect to local networks through
VPNs from any type of device, whether it be a desktop computer, a laptop, a tablet or even
a mobile phone, and from any geographical location as long as they have an internet connection.
Some individuals even utilise VPNs to connect to networks in other locations in order to then
connect to the rest of the world with the appearance of being in that physical locations.
In short VPNs work by creating a tunnel to connect the two end points (computers, networks
etc) through which all information can travel securely. These tunnels are virtual connections
which replace the older physical systems such as the dedicated leased lines that businesses
would previously have had to invest in to connect their local networks together.
The virtual tunnels actually involve the sending and receiving of packets of encrypted
information which are encapsulated within outer packets. The outer packets are also encrypted
and pre-programmed with their source and their destination, and only the destination points
are configured to decrypt them.
The packets are used in conjunction with authentication measures at each end to ensure
that the correct users and devices are accessing the connection. If anyone intercepts the packets
as they take their journey across the public networks, they will only be able to determine the
firewall⁄gateway server that they are heading towards, but none of the data contained
within them or their final destination on the local network.
Types of VPN
There are three types of VPNs that provide users with the functionality described above
and these fall within the two categories: computer-to-network VPNs and
Computer-to-network VPNs, or remote access VPNs, connect users on individual devices
to a remote network via the internet as if their device was actually on the network in its original place.
The user simply installs software on their machine which creates the secure connection to a
gateway or VPN server on the local network. They're the solution for employees working from
home or on the move who need to "remote in" and access work networks, files and systems.
Network-to-network VPNs, or as they are commonly referred to, site-to-site VPNs, in short
connect two separate local networks across the internet forming one virtually unified network,
using VPN servers on each network rather than software on individual machines. They can be
further broken down into Intranet vs Extranet VPNs.
Intranets allow users⁄employees within the same organisation to log in to a conjoined
secure network from multiple office locations. As well as being password protected to authenticate
each user, these intranets are usually restricted to only accept connections from the specified
networks. They are therefore ideal for businesses which are spread across different geographical
sites so that employees can work on the same files, folders and systems seamlessly without
having to replicate these on each network or transfer them less securely across the internet.
Extranets work in a similar way, however they are used to provide a common network space
for users not just across locations but across organisations. The networks that are connected
together are therefore under the control of these distinct organisations and their respective
network administrators. The common example would be a secure network accessed by both a supplier
and their client. The scope of the virtual network would be more limited so that the organisations
don't have access to each other's entire networks and intranets.
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More Networking Protocols and Standards:
• IEEE 802.11.x Wireless Standards
• IEEE 802.11 Wireless Modulation Methods
• Kerberos Authentication Protocol
• Network Routing Protocols - IGRP, EIGRP, OSPF, ISIS, BGP
• OSI Transport Layer
• Comparison of the Layers of the OSI and TCP/IP Models
• VTP (VLAN Trunking Protocol)
• IPv6 Neighbor Discovery Protocol (NDP)
• Video - Network Layer (Layer 3) of OSI Networking Model