Do You Know What Follows

Sunday 27th December 2009

"Exploit Wednesday", of course

In the main, members of the criminal fraternity are far from being the stupid, striped-vest and mask-wearing bunch so beloved of cartoonists, unfortunately for the rest of us.

Criminals are only too well aware that many people regard the regular Update downloads for Microsoft operating systems as little more than a nuisance.  As a result, they know that the delay in applying the security patches creates a temporary "window of opportunity".  The strategy is really quite simple.  By downloading and inspecting the security patches as quickly as possible after they are released, it may be possible to determine the nature of the weaknesses which are being addressed.  Any systems which have not yet applied them are, therefore, potentially vulnerable to being exploited for use in botnets etc.

In order to minimise the chances of such exploits succeeding, it is vital to ensure that all Microsoft updates are applied as quickly as possible.  It is equally essential to keep anti-virus and firewall software fully up-to-date.  To use out-of-date versions of such software is worse than not having them at all, due to the false sense of security which results.

Go On, Give A Burglar Some Christmas Cheer!

Sunday 20th December 2009

At least, you could make life easy for the poor chap - it is Christmas, after all......!

"Social Networking" websites such as Facebook are now very popular indeed.  Unfortunately, this popularity extends to members of the criminal fraternity, who have discovered that such websites provide a rich vein of information which may be used for their nefarious purposes.

The Police Crime Prevention Units regularly publish advice on how motorists may reduce the risk of thieves stealing valuables from their car when it is unattended.  Such advice includes the sensible recommendations that unattended vehicles should always be locked and any valuables should be removed or, at the very least, locked away
out-of-sight in the boot.  The principle really is very simple - if a valuable item is on open display, a dishonest person may be unable to resist the temptation to try and steal it.  If, however, he cannot see anything valuable, he will not usually bother breaking in to the car "just in case...".

When posting information to Facebook, some people have found to their cost that their entry had reached a somewhat wider audience than they had intended.  It is all very well putting up a note advising your friends that you are going away on a fortnight's holiday over Christmas.  However, if the Facebook profile includes an address, or if the information can be deduced from other sources, this amounts to an open invitation to burglars.  After all, who would go away and leave a large note on the front door advertising the fact?  Similarly, people have discovered just how quickly their prized new 50" flatscreen television is replaced with an equally large, but empty, space when they have put up its details on Facebook.

The fundamental problem is the common misconception that the Internet is somehow "private" or "trustworthy", in a manner which does not apply to any other area of Society.  Far from being "private", the Internet is actually "public" in the extreme.  Worse, whilst it is rather easy to publish information on the Internet, it can be well-nigh impossible to remove it subsequently.  Therefore, you should never post any information on the Internet unless you are willing for it to be accessed by all and sundry, including those whose moral standards are somewhat less admirable than your own.  

What Price Traditional Hard Disks Nowadays?

Sunday 13th December 2009

Only about one-tenth of the price of solid-state disks!

Hard disks have been fitted in consumer-grade computers for so long now that many people cannot remember a time when they did not exist.  Over the years, hard disk capacities and access speeds have soared, at much the same rate as their prices have plummetted.  Nevertheless, the basic technology has not changed and still relies on a rotating platter or platters, over which the read-write heads move.  By the standards of mechanical devices, modern hard disks are unbelievably reliable and long-lasting.  However, they do consume power and generate heat, they can be a little noisy and they do eventually fail, usually at the worst possible time.

The solid-state disk, or SSD, uses much less power and generates less heat.  It is also entirely silent, as it has no moving parts.  The technology is not particularly new - Cisco routers and switches have always stored their operating system and related files in "Flash Memory", rather than mechanical hard disks.  Unfortunately, SSD's have two drawbacks.  One is that they have, until now, been unable to offer the same lightning-fast access speeds as traditional hard disks, while the other is that they are not cheap. 

Cisco equipment is well-known for being as reliable and long-lasting as it is expensive.  A Cisco router or switch boots up in much the same way as does a regular PC, except that its boot device is its "Flash" rather than a hard disk.  Like a PC, it then copies as much of the operating system as possible into RAM, which is both relatively cheap and fast.

The exorbitant prices of SSD's have now come down to a level where they can be used in mid-range PC's, in a specialist technique which mirors that used by Cisco. 

Windows enjoys a well-deserved reputation for being slow to boot from a hard disk.  The latest generation of SSD's are being used to address this.  The idea is simple - use a small, but very fast, SSD as a "system" disk to boot Windows, then switch to a regular hard drive to load applications, data etc.

Gradually, fast SSD's will become affordable in sizes greater than about 10Gb and the hard disk will go the same way as 3.5" floppy disks (remember them?), but that day is still several years away.

Hurrah For The OSI 7-Layer Stack!

Sunday 6th December 2009

What? You have never heard of it?

Without a shred of doubt, the OSI 7-Layer Stack is one of the great unsung heroes of our time.  Without it, you would be unable to read this blog and even the Internet itself could not exist.

But just why is it so vital?

The earliest computers were so large and expensive that even a single computer was out of the reach of all but the largest companies.  However, as prices dropped it became commonplace for a company to have a number of computers scattered around their organisation.  When IBM, DEC and the other manufacturers realised how useful it would be if a company could link all its computers together, they each designed their own proprietary networking hardware and protocols to provide this feature.  The obvious consequence was that IBM equipment could communicate only with IBM equipment, DEC with DEC and so on.  At first, this was not a problem, since a company would normally use only a single manufacturer's equipment.  An "IBM shop", for instance, would not dream of using anything not manufactured by "Big Blue".  However, as the tecnology developed, the need arose for the IBM computers at company "A" to communicate with the DEC computers at company "B".  Special converters were therefore produced, but this was hardly a scalable solution.

This is where the OSI 7-layer Stack comes in.  Its universal reputation rests primarily on three pillars:

1) It is "open", which means that anyone and everyone may use it without restriction or licence fees etc
2) It is a "standard", therefore guaranteeing interoperability among compliant implementations
3) It is "layered" and each layer interacts only with the one immediately above or below it - no "short cuts" are permitted

At the bottom is Layer 1, the Physical Layer, which deals with cables, connectors and the like.  For example, when someone is surfing the Internet, it makes no dirrerence to their browser whether their computer has a wired or a wireless connection.  In fact, the browser does not even know about the existence of the Physical Layer, because it is operating at Layer 7, the Application Layer.  The web pages may be hosted on a server at the other side of the world and that server may be a Dell, IBM or HP etc.  As the web pages make their journey to the surfer's computer, they will travel across various media and pass through various manufacturers' equipment.  Some of the routers and switches may be Cisco, others Juniper or Foundry Networks.  The surfer's own router and computer could each be manufactured by any one of dozens of companies.  Nevertheless, it all interoperates perfectly.  This is the triumph of the OSI 7-Layer Stack.

On a heavier note, here are two mnemonics to help recall the names of the layers:  "All People Seem To Need Data Processing" and, slightly less grammatical, "A Policeman Said To Never Do Pot".