network security
introduction
Network security is the business of stopping bad guys fiddling around with a network. E-commerce cannot exist without network security.
A network attack is a virtual attempt to damage or compromise part of the LIC. It starts in either the Internet or the enterprise network. Network defence is the job of protecting the LIC from these attacks. A physical attack, like applying a baseball bat to a computer, falls in the realm of physical security.
what it is
We want to keep our Internet conversations safe from bad acts of naughty people. In the physical world they can steal our computers or damage them. In the virtual world naughty people can invade our privacy, corrupt our data, steal our information and pretend to be us.
Years ago, the Internet was growing in popularity as a source of information. Lots of companies started advertising their products on websites. These companies wanted to be able to sell their products via their websites, but couldn't. The Internet was crap as a marketplace because it was an inherently insecure network.
If an Internet user sits at their desk looking at a company website, there is a series of messages sent back and forth between the web browser and the company webserver. A message does not travel direct from browser to server: it makes several hops from one computer to the next over the Internet. A hop is an intermediate connection in a string of connections linking two network devices. On the Internet most data packets need to go through several routers before they reach their final destination. Each time the packet is forwarded to the next router, a hop occurs. The more hops, the longer it takes for data to go from source to destination.This kind of communication is so quick that the user may only notice a couple of seconds delay for a web page travelling 10,000 miles.
| LIC topology: web page travelling five hops across the Internet | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| web server |  |
company's ISP | |
an Internet router | |
another Internet router | |
customer's ISP | |
web browser | ||
The basic problem is that at any point a message can be copied or changed. Any clever person at any of the points used for these hops can copy the message. This is unavoidable due to the construction of the Internet. Examining a copied conversation is boring if the user is browsing through paint drying web sites, but interesting if credit card numbers or intimate photographs are involved.
Before any reasonable buyer is going to give their credit card number to a website, they must be convinced that their conversation is safe. Before a vendor sends valuable information to a customer, he must be convinced that the information cannot be copied in transit and cannot be changed before it arrives at its destination. He must also be sure that the customer is not in fact just a teenage boy, who should really be playing football and not intercepting Internet traffic, pretending to be a customer. They need security.
This need for security is not unique to the Internet. Because of the need to ensure that only those eyes intended to view sensitive information can ever see this information, and to ensure that the information arrives un-altered, security systems have often been employed in computer systems for governments, corporations, and even individuals. Billions of dollars of retail purchases occur over the Internet each year. That is a lot of cash that needs to be kept secure.
what it isn't
Anything to do with security guards.
where it is
It ought to be everywhere. Anyone who connects their computer to the Internet can expect a hack attempt within a few minutes. Unfortunately many people do not understand the value of a virus checker, spyware checker and a firewall.
history
In 1967 computers start storing passwords in an encrypted form.
In the 1980s people with a scanner that operated at the right frequency could easily listen to calls on other peoples cordless telephones and analog cell phones. War dialling became a new nerd hobby: automated phone diallers churned through half the phone book looking for modems connected to networks.
In 1985 the term hacker was introduced.
In 1988 the student Robert Morris created the Morris Worm, the first worm virus.
In the late 1980s Clifford Stole wrote a book about cyber-crime called "The Cuckoo's Egg" which caused great consternation about how vulnerable computer networks were to bad guys.
In the 1990s war driving was invented: driving round with a computer and an antenna, looking for wireless networks to break into.
