Internet connectivity mechanisms

Internet connectivity mechanisms

Now anybody can access the Internet and get it's benefit. There are several ways to connect to the Internet.

Dial-UP

ISDN

DSL

Cable connections

Wireless connections

T-1, T-2 and T-3 lines

Satellite

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Dial-UP

• Dialup is simply the application of the Public Switched Telephone Network (PSTN) to carry data on behalf of the end user. It involves a customer premises equipment (CPE) device sending the telephone switch a phone number to direct a connection to.

• Speed ranges from 2400 bps to 56 Kbps

• Twisted pair (regular phone lines) is the physical medium.

• Cheap but slow compared with other technologies.

• Speed may degrade due to the amount of line noise

ISDN

• Integrated Services Digital Network is a telephone system network. ISDN is integrates speech and data on the same lines, adding features that were not available in the classic telephone system. access interfaces

  • Basic Rate Interface (BRI)

  • Primary Rate Interface (PRI)

  • Broadband-ISDN (B-ISDN)

• Dedicated telephone line and router required.

• Speed ranges from 64 Kbps to 128 Kbps.

• Physical medium is Twisted pair.

• Not available everywhere but becoming more widespread.

• An ISDN line costs slightly more than a regular telephone line, but you get 2 phone lines from it.

• 56K ISDN is much faster than a 56K dialup line

Digital subscriber line ( DSL )

• Digital subscriber line ( DSL ) is more expensive than dialup, but provides a faster connection. DSL also uses telephone lines, but unlike dialup access, DSL provides a continuous connection to the Internet.

• This connection option uses a special high-speed modem that separates the DSL signal from the telephone signal and provides an Ethernet connection to a host computer or LAN.

• Doesn’t interfere with normal telephone use.

• Bandwidth is dedicated, not shared as with cable.

• Bandwidth is affected by the distance from the network hubs. Must be within 5 km (3.1 miles) of telephone company switch.

• Limited availability.

• Not networkable

Cable Internet

• A cable Internet is a connection option offered by cable television service providers. The Internet signal is carried on the same coaxial cable that delivers cable television to homes and businesses.

• A special cable modem separates the Internet signal from the other signals carried on the cable and provides an Ethernet connection to a host computer or LAN.

• CMTS is the equipments provides the Cable Internet service to the users. It provides the same service which DSLAM offers.

• 512 Kbps to 20 Mbps

• Coaxial cable and in some cases telephone lines used for upstream requests as physical medium

Wireless

• Access is gained by connection to a high speed cellular like local multi-point communications system (LMCS) network via wireless transmitter/receiver.

• Speed is 30 Mbps or more

• Physical medium is Airwaves (antenna)

• Can be used for high speed data, broadcast TV and wireless telephone service.

Satellite

• Satellite connection is an option offered by satellite service providers.

• The user's computer connects through Ethernet to a satellite modem that transmits radio signals to the nearest Point of Presence, or POP, within the satellite network.

• Newer versions have two-way satellite access, removing need for phone line.

• In older versions, the computer sends request for information to an ISP via normal phone dial-up communications and data is returned via high speed satellite to rooftop dish, which relays it to the computer via a decoder box.

• Speed is 30 Mbps or more

• Physical medium is Airwaves (antenna)

• Bandwidth is not shared.

• Satellite companies are set to join the fray soon which could lead to integrated TV and Internet service using the same equipment and WebTV like integrated services

• Latency is typically high

• Some connections require an existing Internet service account.

Frame Relay

• Provides a type of "party line" connection to the Internet.

• Requires a FRAD (Frame Relay Access Device) similar to a modem, or a DSU/CSU.

• speed ranges from 56 Kbps to 1.544 Mbps (or more, depending on connection type)

• Various physical mediums used

• May cost less than ISDN in some locations.

• Limited availability.

• Uses one of the connection types below, fractional up to OC3

Fractional T1 (Flexible DS1)

• Only a portion of the 23 channels available in a T1 line is actually used.

• Speed ranges from 64 Kbps to 1.544 Mbps

• Physical medium is Twisted-pair or coaxial cable

• Cheaper than a full T1 line with growth options of 56 Kbps or 64 Kbps increments as required.

T1

• Special lines and equipment (DSU/CSU and router) required.

• Speed 1.544 Mbps

• Physical medium is Twisted-pair, coaxial cable, or optical fiber

• Typically used for high bandwidth demands such as videoconferencing and heavy graphic file transfers.

• Minimum for large businesses and ISPs.

• Expensive

T3

• Typically used for ISP to Internet infrastructure.

• Speed 44.736 Mbps

• Physical medium is Optical fiber

OC-1

• Typically used for ISP to Internet infrastructure within Internet infrastructure.

• Speed 51.84 Mbps

• Physical medium is Optical fiber

OC-3

• Typically used for large company backbone or Internet backbone.

• Speed 155.52 Mbps

• Physical medium is Optical fiber

The history of the Internet in brief

Here is the brief history of the Internet:



ARPA (1957)

There is a competition between USSR and USA for technology and USSR won it by launching Sputnik. Then USA launched the Advanced Research Projects Agency (ARPA) under the auspices the Department of Defense. Launching the ARPA is mainly focused to maintain a technological lead, particularly with regards to the military.



Packet Switching (1968)

USA wanted to expand the ARPA project to make it reliable at any time. Then the invented packet switching. National Physical Laboratory created the first packet switching network in 1968.



ARPANET (1969)

ARPA created ARPANET in 1969 to help ARPA-funded researchers collaborate more effectively for non profit uses like education and researches which were based on the packet switching technology built at the Rand Corporation in the early 1960s. The first ARPANET were positioned at UCLA, Stanford Research Institute, University of California at Santa Barbara, and University of Utah in Salt Lake City.



TCP/IP (1983)

Between 1969 and 1983, a variety of individual networks sprouted and grew. (BITNET,CSNET). Connecting each of these independent networks was difficult, though, because they didn't use the same protocols and therefore couldn't exchange information.

As a result, ARPA commissioned the development of a new protocol called Transmission Control Protocol/Internet Protocol (TCP/IP) that would allow different networks to connect.

Most networks had changed to TCP/IP in the late 1970s, but ARPANET didn't make the change until January 1, 1983. Thus, many folks consider that date as the birthday of the Internet.


NSF Creates NSFNET (1986)

In 1986 the National Science Foundation created NSFNET, an Internet backbone with a speed of 56K. This backbone connected five super-computing centers located at Princeton, Pittsburgh, UCSD, UIUC, and Cornell. NSFNET precipitated a large number of connections from various universities.

NSFNET has been updated continually since 1986. In 1988, two years after going online, the backbone was upgraded to T1 (1.544M). In 1991, it was upgraded to T3 (44.736M)

ARPANET Is Dismantled (1990)

Newer networks connected the sites that ARPANET connected, and thus ARPANET was no longer useful.

The World Wide Web (1992)

Tim Berners-Lee, a physicist at CERN in Switzerland, invented the World Wide Web (Web) in 1992 as a way to organize information in a more brain-like fashion. His idea was to allow people to make multiple free associations with different bits of information.



NSF Establishes InterNIC (1993)

NSF created InterNIC, a group of businesses that provide a variety of essential services to the Internet.

The Internet Today

The growth of the Internet has been explosive. In 1985, there were about 2,000 host computers on the Internet. Now there are millions of host computers and many more millions of actual users. Now Internet isn't limited to educational and research purpose but also in too many fields like commercial and welfare services and etc.

Note to new Linux users: No antivirus needed

Savvy Windows users have to watch their virus checkers as closely as the head nurse in the ICU keeps an eye on patient monitors. Often, the buzz in the Windows security world is about which protection-for-profit firm was the first to discover and offer protection for the malware du jour -- or should I say malware de l'heure? The only thing better than having backed the winning Super Bowl team come Monday morning at the office coffeepot is having the virus checker you use be the one winning the malware sweepstakes that weekend.

If a rogue program finds a crack in your Windows armor, paying $200 per infection to have your machine scrubbed and sanitized by the local goon^H^H^H^H geek squad not only helps to reinforce the notion that you have to have malware protection, but that it has to be the right protection, too. The malware firms are aware of this, and all of their advertising plays upon the insecurity fears of Windows users and the paranoia that results. Chronic exposure and vulnerability to malware has conditioned Windows users to accept this security tax.

It's no wonder, then, that when Windows users are finally able to break their chains and experience freedom on a Linux desktop, they stare at me in disbelief when I tell them to lay that burden down. They are reluctant to stop totin' that load. They have come to expect to pay a toll for a modicum of security.

I try to explain that permissions on Linux make such tribute unnecessary. Without quibbling over the definitions of viruses and trojans, I tell them that neither can execute on your machine unless you explicitly give them permission to do so.

Permissions on Linux are universal. They cover three things you can do with files: read, write, and execute. Not only that, they come in three levels: for the root user, for the individual user who is signed in, and for the rest of the world. Typically, software that can impact the system as a whole requires root privileges to run.

Microsoft designed Windows to enable outsiders to execute software on your system. The company justifies that design by saying it enriches the user experience if a Web site can do "cool" things on your desktop. It should be clear by now that the only people being enriched by that design decision are those who make a buck providing additional security or repairing the damage to systems caused by it.

Malware in Windows Land is usually spread by email clients, browser bits, or IM clients, which graciously accept the poisoned fruit from others, then neatly deposit it on their masters' systems, where malware authors know it will likely be executed and do their bidding -- without ever asking permission.

Some malware programs require that you open an attachment. Others don't even require that user error. By hook or by crook, malware on Windows often gets executed, infecting the local system first, then spreading itself to others. What a terrible neighborhood. I'm glad I don't live there.

On Linux, there is built-in protection against such craft. Newly deposited files from your email client or Web browser are not given execute privileges. Cleverly renaming executable files as something else doesn't matter, because Linux and its applications don't depend on file extensions to identify the properties of a file, so they won't mistakenly execute malware as they interact with it.

Whether newcomers grok permissions or not, I try to explain the bottom line to them: that because they have chosen Linux, they are now free of having to pay either a security tax up front to protect themselves from malware, or one after the fact to have their systems sterilized after having been infected.

So Linux is bulletproof? No. Bulletproof is one of the last stages of drunkenness, not a state of security. Linux users, like users on every operating system, must always be aware of security issues. They must act intelligently to keep their systems safe and secure. They should not run programs with root privileges when they are not required, and they should apply security patches regularly.

Misleading claims and false advertising by virus protection rackets to the contrary, you simply don't need antivirus products to keep your Linux box free of malware.

Source: By Joe Barr, Monday, 26 February 2007 08:00 Linux.com

http://www.linux.com/news/software/applications/8261-note-to-new-linux-users-no-antivirus-needed

posted by K.W. Roshan Herath

Group of Microsoft Rivals Nears Patent Deal in Bid to Protect Linux

Microsoft Corp. has suggested in recent years that companies using the Linux computer-operating system might be violating Microsoft patents. Now, in an effort to avert any legal threat that might discourage the adoption of Linux, a group of Microsoft rivals is about to acquire a set of patents formerly owned by the software giant.

Linux is a free open-source operating system that has gained ground against Microsoft's Windows software among business users, especially in servers, the big back-office computers inside companies. Linux's fans say the free software is more secure than Windows and, because its blueprint is open to users, can be more easily customized.

The group, which includes major corporate supporters of such open-source software -- including International Business Machines Corp., Red Hat Inc. and Sony Corp. -- said it is nearing an agreement to acquire 22 patents that Microsoft sold to another organization earlier this year. Though the issue hasn't been tested in court, the patents may relate to Linux.

The group, the Open Invention Network, argues that its acquisition will protect users of Linux software from expensive lawsuits that could result if the patents fell into the hands of "patent trolls," groups that don't typically make products and exist primarily to earn money from lawsuits and settlements in patent cases.

The group said it is close to signing a deal to acquire the patents from Allied Security Trust. AST buys patents to protect its members from patent litigation, provides them with licenses to the technology, and then resells the patents on the open market. OIN and AST, whose members include Verizon Communications Inc., Cisco Systems Inc. and Hewlett-Packard Co., could announce an agreement as early as this week.

AST won control of the patents in a private auction held by Microsoft. OIN and AST said their cooperation ensures that the Microsoft patents won't end up with patent trolls, leaving some big boosters of Linux potentially exposed. "We have averted a scenario where these patents can be used for negative purposes," said Keith Bergelt, chief executive officer of OIN, which holds on to its patents and broadly licenses them.

Financial terms of the deals aren't being disclosed.

Mr. Bergelt said Microsoft presented the patents to potential bidders in its auction as relating to Linux. A Microsoft executive declined to say how the company described the patents to bidders.

Microsoft's sale of the patents is a new twist in its approach to Linux. Microsoft executives have previously said that the company holds more than 200 patents, out of the company's total portfolio of more than 50,000 patents, that they believe are violated by Linux software. In recent years, Microsoft has entered into patent-licensing pacts with dozens of companies that distribute or use open-source software in their products.

Earlier this year, Microsoft went a step further and filed a lawsuit in federal court in Seattle against the Dutch GPS device maker TomTom NV for allegedly violating Microsoft patents related to Linux, which were used in TomTom navigation products.

That suit, Microsoft's first Linux-related action and its first-ever alleging infringement of a software patent -- caused a stir among open-source advocates who feared Microsoft might be mounting a major legal offensive against Linux users. Microsoft and TomTom subsequently settled the suit for undisclosed terms.

Dave Kaefer, general manager for intellectual-property licensing at Microsoft, disputed allegations by some open-source advocates that the company intended to disrupt the market for Linux products with the sale of the patents, arguing that it wouldn't have sold the patents to AST, a firm whose members also include Linux boosters, if its goal had been disruption.

Mr. Kaefer said the patents, acquired from Silicon Graphics, were sold because they weren't strategic to the company. "They weren't important to our business going forward," he said.

Source:
By NICK WINGFIELD
http://online.wsj.com/article/SB125236988735891147.html?mod=googlenews_wsj
[ accessed on 08th Sep, 2009 ] by K.W.Roshan Herath

How to mount an .iso image on Linux

How to mount an .iso image on Linux

When we use CD/DVD images to burn into a CD/DVD, normally we can't see the files which included inside the CD/DVD without burning them into a CD/DVD. IF you use Linux
Operating System, you never need to burn the .iso file into a CD/DVD to see the files inside the .iso image file.

At first you must have the root user. You can simply do it by typing su on basic linux terminal window ( if you use *buntu system you can type sudo instead of su ) and providing the correct password. Then the prompt will change to the root user.
Then make a directory in /media folder to mount iso files. ( in most linux distros /media is the place which mount CD/DVD. )

Syntax : mkdir /media/folder_name
folder_name should be the name of the folder which used to mount iso files.

Then mount the CD/DVD iso images into the folder which we created before.

Syntax : mount image_file path_to_the_folder -t iso9660 -o loop

image_file is the name of the iso file with the path and .iso extention
path_to_the_folder is the place of the folder which we created
before.

Now you can open the the .iso file as a normal CD/DVD inside the Drive.
To unmount the image file from the location use

umount /media/folder_name


posted by K.W.Roshan Herath [ roshanherath ]