If you access the Internet using a laptop or smartphone from a Wi-Fi hotspot at a coffee shop or airport, or plug your laptop into the network at a hotel or conference center, then you're running an unnecessary security risk.

That's because it's not hard to intercept data on local networks that are open to the public. The man sipping coffee at the next table or the woman in the room down the hall in your hotel could be trying to steal your email username and password or to take a copy of your confidential spreadsheet as it goes from your computer to its destination.

The way to protect your confidential data as it travels over these high risk local networks is to use a virtual private network (VPN). When you set up a VPN between your laptop, iPhone or Android and a VPN server, all your Internet traffic is automatically encrypted and diverted to the VPN server, where it is decrypted and sent on to its final destination.

Incoming traffic such as email is also diverted to the VPN sever, where it is encrypted before being sent on to you. It's only once it travels through the local network and arrives safely at your laptop or smartphone that it's automatically decrypted.

The three most common VPNs you'll come across are OpenVPN, L2TP/IPSec and PPTP. OpenVPN is very secure, but it requires the installation of client software. It can be tricky to set up, especially on smartphones, and it can't be used at all on an iPhone, unless the iPhone has been jailbroken. L2TP/IPSec VPNs are very secure and usually don't need any additional software for most laptops or smartphone including Android and iOS. PPTP VPNs are the easiest to set up, don't require additional software for most laptops or smartphones, but they offer a slightly lower level of security and may be blocked so they don't work on some networks. See below for the different providers of these services.

If you work for a reasonably large organization then you may be able to use your company's VPN server. Alternatively , if you work for a small business or from home you could consider setting up your own VPN server.

In case you want to do it yourself , you can find full instructions for setting up an OpenVPN server on a Windows, Mac or Linux in an article I wrote over at EnterpriseNetworkingPlanet.com and setting up a PPTP VPN server on Windows XP and Windows 7.

But without doubt the easiest way to access a VPN is through a VPN service provider. Some things to consider when selecting a VPN service provider are:

  • What types of VPN do they offer? If you intend to use an iPhone then don't choose a service provider that only offers OpenVPN.
  • Do they offer a money back guarantee? Unfortunately, the only sure way to find out if a VPN service is fast enough for your needs is to actually use it but a lot of providers do offer money back guarantees.
  • Where are the VPN servers located? Performance tends to suffer if you connect to a VPN server located a long distance away from where you are. If you are likely to travel overseas then it's sensible to choose a VPN service provider which offers VPN servers in the countries you plan to travel to.
  • Do they bill monthly, or do they offer day or weekly rates? If you only need a VPN for a short period while you are travelling then buying a day or three day pass from a company like HotspotVPN (see below) makes financial sense.
  • Is there a data volume cap? If you are unlikely to be transferring large volumes of data then look for a service provider that offers a cheaper service with a data volume cap. Unlimited services can suffer from poor performance because they attract customers using the VPN to download huge volumes of data such as pirated movies over peer to peer networks.
  • Do you need to use peer to peer networks? Some VPN service providers block these services, even for legitimate purposes, to prevent their services becoming congested.

VPN service provider guide

Banana VPN (L2TP/IPSec, PPTP, $14.99 per month or $60 for six months) - 100% refund available within first few days. Servers are in U.S. but European servers also available as separate service.  Peer to peer and file sharing is blocked. Unlimited.

Black Logic (PPTP, from $8.00 per month) - Partial refunds are available in first seven days. Servers are in U.S., UK, Canada and Europe. Unlimited.

ExpressVPN (OpenVPN, L2TP/IPSec, PPTP, $12.95 per month, $59.95 for six months, $99.95 per year) - 30 day money back guarantee. Servers are in U.S., Europe and East Asia. Unlimited.

Golden Frog (OpenVPN, L2TP/IPSec, PPTP $14.99 per month for PPTP only, $19.99 per month for all three VPN types) – You can cancel any time, which is nice. Servers are in U.S., the Netherlands, Hong Kong, and the UK. Unlimited.

HideIP VPN (OpenVPN, L2TP/IPSec, PPTP, from $5.99 per month , $30.99 for six months, $54.99 annually depending on which servers you wish to access) - Free three hour trial -- good to check your speed with. Two day money back guarantee if you are unable to get system working but, not for speed issues. Servers in are U.S., UK, the Netherlands, Canada, and Germany. Unlimited.

Hide My Ass (OpenVPN, L2TP/IPSec, PPTP, $11.52 per month, $50.66 for six months, $78.66 per year) - 30 day money back guarantee. 160 VPN servers in 30 countries. Unlimited.

HotspotVPN (OpenVPN, PPTP, $3.88 per day, $5.88 for three days, $6.88 for seven days, $8.88 per month, $88.80 per year - OpenVPN 128 Blowfish $10.88 per month, $108.80 per year -AES 192 $11.88 per month, $118.80 per year- AES-256 $13.88 per month, $138.80 per year. Includes free PPTP VPN

IBVPN (OpenVPN, L2TP/IPSec, PPTP, $4.95 per month, $10.95 for three months, $19.95 for six months, $36.95 for one year for just U.S. and Canadian servers. For all servers: $7.95 per month, $19.95 per quarter, $36.96 for six months, $69.95 per year) - Two hour free trial. 10 day money back guarantee. Servers in U.S., Canada, UK, Germany, Netherlands, Ireland, France, and the Czech Republic. Peer to peer and file sharing are blocked. Unlimited.

Overplay (OpenVPN, L2TP/IPSec, PPTP, $9.95 per month) - 48 hour unconditional money back guarantee. Servers in 46 countries. Unlimited.

PureVPN (PPTP, L2TP/IPSec, $9.95 per month, $74.95 per year, 30 Gig download limit. For unlimited data transfer $18 per month, $160 per year) - 100% three day money back guarantee. Servers in 10 countries. Limited and unlimited accounts available.

RoadwarriorVPN (OpenVPN, $19.95 per month, $125.99 for six months, $199.95 for one year) – You can cancel at any time. Servers are in U.S., UK, the Netherlands. Unlimited.

StrongVPN (OpenVPN, L2TP/IPSec, PPTP, from $7.00 per month) - Seven day unconditional money back guarantee. Servers in U.S., UK and the Netherlands. Unlimited.

Witopia (OpenVPN, L2TP/IPSec, PPTP, OpenVPN, $59.99 per year, PPTP L2TP/IPsec $39.99 per year; All three VPN types, $69.99 per year) - 30 day money back guarantee. Servers are in U.S. and 31 other countries. Some illegal sites blocked. Unlimited.

Paul Rubens has been covering IT security for over 20 years. In that time, he has written for leading UK and international publications including The Economist, The Times, Financial Times, the BBC, Computing and ServerWatch.