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Archive for September, 2014


What’s a Proxy Server?

When I first started working in IT a few decades ago, a proxy server was known as an application gateway.  That definition still is fairly accurate in some contexts, but in the world of the internet it sounds a little dated.   In technical terms a proxy server is an application that sits between and mediates traffic between two or more network segments.

The proxy is a middle man, it sits between source and destination systems, in fact it ensures both never actually directly communicate with each other.    In this description your computer/laptop/smartphone is the source system requesting information from the web servers which are the destination systems.


The concept is easier to understand from the above illustration which shows how a proxy sits in between various computers and their destinations, receiving and forwarding data as required.    It’s important to know that a proxy doesn’t actually intelligently route information – it simply forwards it, there are no decisions on routing made at all other than a basic send and receive.  One of the best analogies of a proxy is to think of a discussion between two people speaking through an interpreter. All communication passes through  the interpreter, their job is to pass data back towards the two people in a format they can both understand.

The language analogy is particularly apt because in some senses the proxy is speaking to completely different systems.  For example the computers might be running different versions of windows, Linux or OSx and the web servers will likely be based on Unix, Linux or Windows server systems – the proxy must communicate and forward data between all these different systems.

So why are proxies so important and widely used now?

Well for the ordinary web surfer there are several distinct properties of proxies that make them incredibly useful – here’s the main ones:

Proxies Hide Your Identity

If a proxy server is properly configured, which is not necessarily the case, then both the sending and receiving computers will have actually no knowledge of each other.   In fact if set up completely securely then the web server will be completely unaware of the existence of the proxy.  In any case, the web site will have no record of the client PC,  it also isolates the computer from any potential security problems such as viruses or malware.

Proxies Also Hide Your IP Address

All over the internet, there are many thousands of sites which restrict access based on your physical location.  This is determined by where your IP address is registered.  Unfortunately many of these sites are the biggest and most popular on the internet – sites like the BBC iPlayer, ITV player, Netflix, Hulu, HBO and NBC to name but a few.  Add to these thousands of forums and social media sites like YouTube, your address can end up restricting you greatly depending on your location.  Using a proxy can solve all this, because the site doesn’t see your address but merely the proxy’s IP address. People use proxies to watch the BBC online from outside the UK, or to watch Hulu beyond the US.

Many services are now available to access these sites, in fact a whole industry has arisen.  Most even have the facility for addresses from smaller countries – fancy watching the hurling on RTE, just pick one that provides an Ireland IP address.

Bypassing Filters

There are many countries in the world, where the internet is heavily censored – in some countries many thousands of sites are inaccessible.  Places like China, Iran and Thailand block access to many sites determined by their leaders.  Even places like Turkey have been known to block popular social sites like Twitter and Facebook from being accessed.

There are a variety of ways that these filters are enforced but most involving blocking access to the web sites or their specific IP addresses. However when you use a proxy as we have learnt you don’t request direct access to the web server, it goes through the proxy server first.  Which means as long as your proxy address isn’t blocked the site will still be accessible.  It is why hundreds of thousands of people use proxies in places like China to access web sites that are normally blocked.  Although if you are concerned about your privacy, using a VPN server which is provides an encrypted tunnel is probably safer.


What is a VPN Server

Throughout the world of networking technologies, there is a lot of confusion about different terms and a VPN is one of those definitions. VPN stands for Virtual Private Network, which is actually quite a wide definition. The main reason for the confusion though is that the technology has developed over the years, so that today’s VPN is very different from the definition used 20 years ago.

For clarity a VPN was traditionally defined as a private network usually provided by a private service to carry voice and data. The more recent definition though has largely superseded this and it is now used commonly to describe a private, encrypted tunnel through the internet, an Internet VPN if you like and this is the definition we will focus on in this post.

What is a VPN used for ?

Well primarily security, a VPN provides a secure way to move packets of data across the internet. This data could be your web browsing, an email you sent, a post to your favorite forum – pretty much anything that leaves your tablet, desktop or PC. The vast majority of this data is normally sent in what’s known as ‘clear text’ meaning that the majority is readable by anyone between you and the recipient. This causes huge concerns obviously, especially if you’re sending passwords, usernames or other pieces of sensitive data. Some security has been bolted on to websites – by using the technology called HTTPS, the secure version of the common web protocol – HTTP. However this is largely only implemented in specific situations like logging on to secure web sites, for the vast majority of the time everything we do online is readable by anyone in between.

So the VPN supplies a method to protect all your data, not simply when you log on to something like a secure banking site. It actually creates a secure tunnel by taking all your data, encrypting it and then packaging (encapsulating in Geek talk!) it into new packets to be distributed securely using a VPN server.

using a VPN


Here’s a simple illustration, which demonstrates how your data is pushed down an encrypted tunnel across the internet.

Practical Uses of a VPN

  • A VPN effectively changes your IP address by masking your real address, any web site or intermediary will only see the location and address of the VPN provider.
  • VPN ensures that there is not a complete log of all your online activity at your ISP.  Normally everything you do online is logged here, but a VPN means it’s all encrypted.
  • You can hide your location with a VPN to access web sites that are normally restricted to specific locations.  You do need to ensure that the VPN server you connect to is in that location – so to watch the BBC online you’d need a UK based VPN server.
  • To circumvent internet filters and blocks instigated by countries like China, Turkey and even Australia

Ultimately a VPN provides privacy and security that simply doesn’t exist in the online world.  Initially it was primarily used by companies and Governments to ensure that all there communication was kept secure.  However now millions of private individuals use them or proxy servers routinely whether to watch Dr Who from the US or to bypass the Chinese filters on thousands of web sites.  Want to use Facebook or Twitter in Iran, try using a VPN.

This video is worth watching for a brief introduction of how to use VPN Tunnel software