What is VPN?
Somehow it happened that even in textbooks do not give an expanded and deep definition of what it is — VPN. Like, and since everything is clear — Virtual Private Network, that is, a virtual private network. And why else discuss something? What is a "network" is understandable: at a primitive level, this is the union of two or more nodes by some kind of communication so that they can exchange information. Naturally, the most convenient way and with the support of all necessary services.
What is "private", also seems to be obvious - not public, and therefore private. That is, in which there are not any who, but only permitted nodes. If you dig a little deeper, it is this component of the VPN that is the most important, as it defines a number of requirements for this very "particular".
First, we need to somehow label the participants of this network and the information that they exchange so that it does not mingle with a stranger. Secondly, it is definitely useful to protect this information from prying eyes. Well at least to encrypt, that again imposes the next circle of restrictions, connected with the stability of this encryption.
Thirdly, it is necessary to preserve the integrity of this method of information transfer-to keep outsiders out of the private network, to check the source of transmitted messages and to ensure that information does not leak anywhere in the "bare state". In general, everything is like on private parties with the powerful of this world: they make a noise in the whole district, but who does what and what does it is not clear. And the severe guard at the entrance and exit suits not only face, but also other places of control.
With the concept of "virtual" everything is a little easier. It just means that such a network is abstracted from the physical component - it does not matter for which and how many communication channels it is laid, since it works transparently for the participants of this network. Or, on the other hand, the physical network most often simply does not belong to the virtual user.
For example, in serious organizations of employees when connecting a working laptop to any wired or wireless networks located outside of this organization, they are obliged to immediately use the VPN connection to the office network. At the same time it does not matter which of these jungles this connection will be established, but there is no doubt that it will go through public — foreign communication networks. Such a connection is called a tunnel, and later this term will be met again and again.
Why do I need a VPN?
The above example of connecting a remote user to a corporate network is one of the most typical scenarios for using a VPN. The user feels at home - more accurately, at home, on vacation or on a business trip, he is able to feel himself at work and can use corporate services without problems.
At the same time, an attacker can not just sniff out what exactly this user is doing, what data he transmits and receives. Moreover, in companies concerned with their own security, all devices used by employees are forcibly included in the mandatory use of VPN connections wherever. Even the use of the Internet in this case goes through the corporate network and under the strict supervision of the security service!
The second most common use case is similar to the first one, only individuals and whole offices or buildings are connected to the corporate network. The goal is the same - reliably and safely combine the geographically remote elements of one organization into a single network.
This can be both large representative offices of corporations in different countries and small companies. Or even just cameras, alarms and other security systems. With such simplicity of creating a VPN, it is not necessary to stretch the cable every time - virtual private networks can also be created inside companies to unite and isolate certain departments or systems.
No less often, VPN-networks are organized between servers or entire computing clusters to maintain their availability and duplication of data. The frequency of their use is directly related to the growing popularity of cloud technologies. And all of the above is not some temporary solutions: such connections can be supported (and maintained) for years.
However, for the average user, another option of practical use of VPN is more important. In our security tips, Android and iOS, it is strongly recommended that you use a secure VPN connection to a trusted host (be it a home router or a dedicated VPN provider) when connecting to any public network to protect your traffic from possible attack by intruders!
Finally, the last use of VPN privately is bypassing a variety of network restrictions. For example, to gain access to resources that are blocked or do not provide their services in a particular territory. According to the report GlobalWebIndex, only in 2014 for access to social networks VPN used about 166 million people.
In general, it is obvious that VPN now - a useful thing, necessary and constantly gaining popularity. Of course, we told about this technology and its capabilities in the most general terms - in real life there are many nuances associated with its use, including legislative, and not only technical.