Designing Home and SME Networks 10 – Getting the Outside In

Once you’ve got your Internet connection, what can you use it for?

Most of us use it to access Internet services, including:

1. Web browsing

   Probably the greatest current use of the Internet. The ‘Web’ (or the World-Wide Web to give it its full name) is a data service that allows users to access and display information contained on devices elsewhere in the world. It uses software called ‘Web Browsers’ which take the data, format and display it, mostly in the form of text and graphics, although audio and video are increasingly used. The two most popular browsers are Internet Explorer ® and Firefox ®. There are many others. The Web is also one of the greatest sources of ‘malware’ (viruses, trojans etc) which will attempt to invade your computer and make it do what the malware writer wants it to. There is no such thing as a fully-secure Web browser, although some are better than others, and the ‘browser war’ continues as browser writers try to out-develop the malware writers and each other. You should never attempt to browse the web unless your computer has a current anti-malware system installed and kept up-to-date. Once you’ve been infected with malware, then your data is no longer secure, your computer can be hi-jacked to perform illegal acts and you could be held responsible…

2. Textual communication –

   Ongoing developments have tended to merge email, SMS texting and Instant Messaging/Chat, so I will consider them as a single item. Although the mechanisms vary, the characteristic of all these services is that they are bi-directional. You use ‘client’ applications on your computer to send messages to other Internet users and they send messages to you. In each case, these are passed through devices (called ‘servers’) that are connected to the Internet. You create your message and despatch it to one of these servers. The server then relays your message to the recipient. Some of these are store-and-forward services, where you have little or no control over when the message is passed on, and others are more-or-less instant, although there is often a significant delay built in (unlike telephone services, where any significant delay disrupts the service). Convergence has now made it possible for you to send SMS messages using an email service and convert Instant Messages into emails (or vice-versa).
   There is a wide variety of applications available for each of these services, and many now support most or all of them.

   All these services can be used as vectors to pass on malware. Of these, email is the most common, often in conjunction with an embedded Web link, but both IM and SMS have got their own malware… Again, don’t use these services without an up-to-date anti-malware application installed on your computer.

3. Audio-visual data –

   Originally, the download of audio-visual content was an adjunct to the Web’s content provision, but it rapidly became a separate entity and is, currently, the rising star of Internet use. Many types of A/V content can be handled by the various web browsers, normally by means of proprietary ‘add-on’ services. More recently, commercial services, such as iTunes ^® and Internet TV from mainstream content providers have become available and tend to use proprietary end-user applications to support download of their services. These allow the content provider much greater control over the use of the downloaded information as well as supporting content charging. Such services are fairly safe to use. Unfortunately, the same cannot be said of general A/V content downloaded using a web browser, as these can contain mechanisms to allow infection by malware.Of particular concern are the distributed download services popularly known a ‘torrents’. These allow peer-to-peer sharing of A/V data and many of them have no mechanism to prevent the download of infected content.

4. Voice over IP (VoIP) –

   The introduction of Skype made the use of a VoIP service practicable for most people. VoIP is a mechanism that provides a voice telephone service across a TCP-IP network such as the Internet. It is a hosted service in that you have a VoIP client on your computer (or as a separate device) that takes voice and converts it to TCP-IP traffic that is directed to a server somewhere on the Internet and relayed to the recipient. Voice signals from the other party are passed back to your client and converted back into sound. Many VoIP services also support video links, instant messaging and file transfer. All but the last are fairly safe to use, but file transfer should be used with caution since any file capable of containing ‘active content’ (such as MS-Word and even PDF) can carry malware.

Summary:

The only guaranteed way to keep your computer safe from malware infections is to lock it in a safe and never turn it on. This is effective but not very useful. Given that Internet access is a reality, you need to take precautions, whatever service you use, to protect your computer from malware infections.

Remember the ‘active content’ rule: any data content that can automatically make your computer do anything at all (and this will vary from client to client) contains the potential to carry a malware infection. These include word-processing files, graphics files, A/V files, executable files (obviously): indeed, almost any file you can think of so be careful what you download, from whom and with which client.

I want to use a service: where do I get the client?

Many computers come bundled with a variety of clients. Be careful using these, as, being the most commonly used, they are also the most commonly targeted: the operating system’s bundled web browser, email and instant messaging clients are prime targets…

Third party clients are often more secure, although, again, as they become more popular, they also become bigger targets for malware writers.

It is not necessarily true that you get what you pay for in the client world: some of the best and most secure clients are available for free.