How a VPN Works Internally

Are you wondering how VPN systems work? Read this article to learn how VPN works internally.

The number of internet-connected devices used throughout the home and office continues to grow year after year, leading to a greater need for optimal protection from online threats. Combined with the fact that those working from home up to five days a week rose from 24% to 31% between 2002 and 2016 in the US, using a VPN to protect data from any unauthorised access is now hugely important.

Thankfully, many individuals and businesses are now aware of the dangers of the web, with many turning to a VPN to enhance their online safety. But, just how does a VPN work internally? In the following article, you'll find out the answer to that very question, and gain a deeper understanding of VPN passthrough. Here's everything that you need to know.

The internal works of a VPN

You probably already know what a VPN is and might already be using one. So, we'll spare you the details regarding the basics. But, if you're hoping to discover exactly how a VPN works, the following section will cover the essentials.

Essentially, a VPN server allows you to avoid outside interference and any interception of private data, all while creating a tunnel through which any user of the connection can enjoy safe and secure web browsing. In order to create tunnels, a VPN follows a process known as encapsulation. This is when packets of data are joined together with additional packets, after which encryption occurs. In turn, this means that intended information will not be subject to any unauthorised access.

As there isn't much difference in VPN functionality across different platforms, all-round protection can be enjoyed on both computers and mobile devices alike. This is something that is particularly useful for businesses who have multiple devices or have a remote workforce that needs to access private information stored on company computers from outside the office.

Even when accessing data remotely whilst using a public WiFi network, a situation whereby data is compromised by cybercriminals will be highly unlikely when an individual is connected to a VPN server. However, unless VPN passthrough is implemented on your router, you might have difficulty when it comes to remotely accessing the files or systems that you need, as this feature needs to be utilised in order to create a secure connection. Continue reading as we take a closer look at VPN passthrough in the next section.

What is VPN passthrough and how does it work?

If you're in search of an effective VPN to create a secure network in your home or workplace, Network Address Translation (NAT) is a term that you may have already come across. Essentially, it is a feature that is supported on most routers, with many modern editions having this feature built-in as standard.

When NAT is enabled on your router, any computer using its secure connection will be assigned the same IP address, with no one from the outside world able to view the true IP address of each connected device. This means that each individual computer will be protected from online threats, with the likelihood of private data being intercepted being heavily reduced.

Another benefit of using NAT is that you will only receive the information you requested, with everything else filtered out using the NAT Firewall. However, achieving this is only possible when NAT is able to process information surrounding both inbound and outbound traffic. If it is unable to do so, then you won't have the ability to connect to a VPN using that particular connection.

Problems arise because certain VPNs use outdated protocols which include the likes of IPSec and PPTP. This means that if you use a VPN which uses either one of these protocols, traffic will simply be blocked by the NAT Firewall. In order to combat this, you need to use a feature known as VPN passthrough. If you do exactly that, you'll have the ability to combine a PPTP VPN with NAT unhindered.

Before you implement VPN passthrough, a component of PPTP known as Generic Routing Encapsulation (GRE), would be the cause for NAT and your VPN not working in tandem. Thankfully, VPN passthrough helps to combat this issue by using an upgraded GRE.

Standard GRE differs in many ways from the enhanced version, but the main thing to consider is that the Call ID is different. The Call-ID used by the enhanced GRE will usually be able to establish a secure VPN connection, whereas with the standard version, it wouldn't be possible.

Many VPNs available today have eliminated the use of such protocols as PPTP and IPSec due them being outdated and unreliable when compared to their superior counterparts such as OpenVPN. As well as this, many modern routers include support for VPN passthrough as standard, which means that you may not need to take the time to set up this feature in the first place.

In order to determine whether or not you need to use VPN passthrough, it's worth checking which protocols your chosen VPN service uses. If IPSec or PPTP aren't listed, or OpenVPN and/or L2TP/IPSec are supported via the VPN, then you should be able to make full use of NAT on your router without any issues. The same can also be said for routers which have built-in VPN passthrough, which means that your VPN can happy coexist with NAT.


Now that you've discovered everything there is to know about how a VPN works, you'll be aware of the processes it follows to secure your web traffic, and exactly why a VPN passthrough is necessary if you are attempting to establish outbound connections unobstructed when using computers on a private network or trying to remotely access files or systems.
Overall, it's clear that VPN passthrough is a useful feature for those who have devices on private networks that need to handle outbound VPN connections without hindrance. So, if you happen to use an older VPN which uses an PPTP or L2TP protocol and need to use it in conjunction with NAT, implementing VPN passthrough might solve your issues.


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