The Hindu Business Line : <I>In the beginning, telephones had no numbers</I>

When the telephone was still a novelty, phone numbers didn't exist. "The local operator just asked for the other party's name, which was labelled on the switchboard," narrate Jim Doherty and Neil Anderson in Internet Phone Services Simplified, from Cisco (www.ciscopress.com) .

As the volume of call traffic increased, and the user base increased, the need for a telephone number was felt. "The numbering system devised and eventually adopted is referred to as the 3-3-4 system," informs the book. The first 3 digits indicated the area code; then came a set of 3 digits as the exchange prefix, and the last 4 digits were the line number.

This was first used in "Wichita Falls, Texas, in 1958, nearly 11 years after the first telephone number was invented." A predecessor to this system was the one- or two-letter exchange name abbreviation along with two to five digits.

What is the current global telephone system? "Wired and wireless phones are connected to either service switching points (SSPs) or mobile switching centres (MSCs)," explain the authors. "Calls are set up between any two places in the network (whether it's a wired-to-wired call, wired-to-wireless call, and so on) by sending digital messages to each other through a common network called the Signalling System 7 (SS7) network. Think of SS7 as a really smart coordinator that helps callers find each other."

A chapter on VoIP (Voice over IP or Internet Protocol) suggests that you might already be using VoIP without even realising it! How so? "Many telephone service providers are starting to use some form of VoIP inside their networks because of the cost efficiencies it can afford them. Many online voice chat services, such as Xbox Live voice chat, Skype, and so on, rely on VoIP."

The richly and colourfully illustrated book has tips from Geek Squad (www.geeksquad.com) , "a 24-hour computer support task force established to protect society from the assault of computerised technology." One such tip cautions that satellite services marketed as `broadband' Internet access may not really suit VoIP. Why? Because "the uplink bandwidth is usually relatively low, and the end-to-end delay of going up and down to and from a satellite can be significant."

Another tip speaks of an odd fact: `comfort noise'. This is the static `injected' by digital systems at the receiving end "to let users know that they have a good connection". Because most people are accustomed to such a background noise in the traditional public telephone system, and in the absence of the noise on a digital phone connection, they wonder if the connection is still live!

Towards the end of the book is a discussion on the future of telephony, and it begins with `the cost battle: consumers versus companies and governments'. The authors say that VoIP is currently cheap because as a service on a data network, it is not regulated yet as a voice communication; and therefore, "not subject to state, local, township, hamlet, regional, provincial, national, hemispherical, or galactic taxes, which tend to add up quickly."

Three features of the `future system' that the book paints are: (a) presence, that is, "the system (with your permission) will know how and where to find you, routing voice communication to the highest level available to you; (b) convergence, meaning "lots of systems, fewer devices"; and (c) preferred formats, be they voice or video, realtime or delayed, so that "you will be able to read your voice mails and hear your e-mails, and you can be see and be seen, as well as hear and be heard."

A book for now!

Security is a process, not a piece of hardware

In computing, firewall means "a system designed to prevent unauthorised access to or from a private network."

Firewall is a 2006 American action/thriller film directed by Richard Loncraine and written by Joe Forte, informs Wikipedia. "It was filmed for a relatively modest budget of $60,000,000." In construction, the word means a passive fire protection; and in automotive mechanics, firewall refers to "the barrier between the passenger and engine compartments of any vehicle."

In computing, firewall means "a system designed to prevent unauthorised access to or from a private network," as www.pcwebopaedia.com defines. "A simple firewall setup is sometimes called a bastion firewall because it's the main line of defence against attack from the outside," write Steve Suehring and Robert L. Ziegler in the third edition of Linux Firewalls, from Pearson Education (www.pearsoned.co.in) .

"Having a firewall doesn't mean you are fully protected," alert the authors. "Security is a process, not a piece of hardware. For example, even with a firewall in place, it's possible to download spyware or adware or click on a maliciously crafted email, thereby opening up the computer and thus the network to the attack."

Chapter 2 explains `packet-filtering firewall' as consisting of "a list of acceptance and denial rules." These rules explicitly define "which packets will and will not be allowed through the network interface." Another chapter guides in `building and installing a standalone firewall,' where you'd learn about fixing commonly used attack vectors at the beginning of the script, and also about `source address spoofing'.

In a chapter on firewall optimisation, the authors state that the goal of optimisation is "to get the packet through the filter processing as quickly as possible, with as few unnecessary tests as possible," where the ideal is to get the packets flowing through `at line speed'.

After the firewall is set up and activated, if you find that nothing works and you're locked out, it is time to read up the inputs on `debugging the firewall rules'. Don't fret, because "firewall rules are notoriously difficult to get right," and so your script may require `customised tweaking'.

Part III of the book begins with `intrusion detection and response'. One of the first questions you need to answer is: "How do you know when you've been attacked successfully?" There are tools available to make intrusion detection more a science than an art, assure the authors. However, the true worth of a human intrusion analyst is proven in his/her ability to assess the situation and present the likely causes and effects.

In a section titled `How not to become compromised', there are three mantras: secure often, update often, and test often. These may seem to be general suggestions, but they have been field-tested to keep systems secure, declare the authors. Remember though, that virtually nothing can be done "to stop an attacker with unlimited resources and unlimited time"

Bastille Linux finds use for securing often. It is "a program that helps automate the process of system security as well as report on the security of the system." Keeping a computer system up-to-date is an often-overlooked aspect of system security, warns the book. "The best way to ensure that a computer will be broken into is to leave it running without updating it."

To test often, you may use Nessus, a program "to test a huge number of known vulnerabilities by attempting to exploit them". Using Nessus, the intrusion analyst can scan for vulnerable software on both local and remote hosts so that those holes can be patched, counsels the book.

Secure read.

Tailpiece

"Do you know why I don't wear synthetic clothes in the computer room?"

"To avoid the static?"

"No, because we use a firewall here!"

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