Monthly Archives: June 2011

Bit Torrent

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From 2004 to 2010, P2P produce the highest Internet traffic, such studies have even suggested the BitTorrent protocol traffic beyond HTTP protocol. BitTorrent itself is a P2P protocol for le sharing, released first in 2001. How It Works BitTorrent is as follows: a user-owned files (called seed) is available on the network, and allow other users (called the peer) is connected, and downloading the file. If then there is one other peer and retrieve the same file, there will be two peers have different pieces of data, as well as that occurs in peer third, fourth, and so on.

When the file has been downloaded was entirely on a peer, the peer is a seed, and helping other peers to get a complete file. Other peer can also accept files with extension *. torrent from seed. This file contains the metadata files that are shared and the tracker information, the computer that coordinates the file distribution. BitTorrent system arranged for more files on a shared computer in a BitTorrent network, the faster the download process.

 

Security Issues behind P2P

Average P2P file sharing is currently supporting the exchange of files with various formats. In terms of security, malware can also enter through the exchange of these files, which often infiltrate the files crack / keygen / warez. Even sometimes P2P software itself contains malware, although the forms of spyware or adware (not a virus), its existence clearly disrupt computer systems. Using P2P software, also means open certain ports, depending on the P2P protocol being used.

In some cases, P2P networks can be exploited to execute DDoS attacks Disributed Denial of Service) by instructing the peer-to-peer networks to try to connect to the website of victims.

 

Other implementations of P2P

In addition to sharing files with all the controversy, and the concept of P2P architecture is also used in other technologies. An example application that enables Skype voice calls over the Internet (voice chat); the concept of cloud computing that has the characteristics of P2P, peercasting technology, and so on.

Clearly P2P is a technology that can help a lot, although its implementation (especially in terms of file sharing) often provokes strong reactions, and who knows how long debated. However, the technology never seems to sleep.

 

Issues on File Sharing

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Talking about file sharing, many controversies arise. One is the issue of illegal file distribution. Although file sharing itself is only a technology that enables the exchange of files and have been first used on the Bulletin Board System (BBS), Usenet, and Internet Relay Chat (IRC), but only the news with the emergence of Napster (founded by Shawn Fanning in 1999) which implements P2P for the distribution of MP3 files, along with the popularity of MP3 is capable of producing good sound quality with a relatively small size, and of course the Internet is widespread support at the time. Napster has three main functions, namely as:
1. Search engines to locate desired MP3 file.
2. File sharing for exchanging MP3 directly across computers.
3. IRC to chat online with other users.

Although implemented in a P2P file sharing, Napster still use the server for users who conduct online index, each of Napster users will be directed to log into the server. Later, the architecture is what causes the Napster service can easily be closed because it still depends on a central server.

In the short time since Napster was released, thousands of Napster users generate thousands of copies of copyrighted songs without the artists and record companies get back in return. Some sources mention different figures regarding the number of Napster users at its peak, ranged from 50 to 80 million users.

Napster’s popularity began to make use of file sharing is highlighted, and culminate in the demands of record companies association, and resulted in the closure of Napster (though later briefly appeared again legally, and allow downloading MP3 paid). Its influence on economic and industrial music into the debate, there are studies that suggest a negative impact of file sharing on sales of recorded music, while other studies concluded that file sharing actually increases sales of popular albums.

File sharing using P2P method does not necessarily stop, the various alternatives and successor to Napster emerged. Among other Gnutella, this is not even limited to MP3 files, but also any file that can be shared. In contrast to Napster, Gnutella does not require the server to do the index, but implementing a mutually pure P2P search online. For example, when a peer in Gnutella network online, then he would tell his existence by giving notification on 8 other peer, each of the eight peer will notify seven other peer, and so on. Each peer has information a large number of other peer is online, as well as content to share.

Decentralization as exemplified Gnutella P2P network makes it virtually can not be disabled, because there is no one central server that manages the user index or the only brain tissue. Le sizes that are shared are also getting bigger, such as files with the video format. The download process can also be performed simultaneously from various peers that have the requested file.

Decentralization as exemplified Gnutella P2P network makes it virtually can not be disabled, because there is no one central server that manages the user index or the only brain tissue. The sizes of files that are shared are also getting bigger, such as files with the video format. The download process can also be performed simultaneously from various peers that have the requested file.

Unlike the software Napster, Gnutella network can be accessed by a variety of different software during the application supports the Gnutella protocol. Some popular software have ever or still uses the Gnutella network, among others, BearShare, iMesh, LimeWire, Morpheus, Shareaza or Xolox. Some software supports multi-network, such as iMesh which in addition supports the eDonkey, Gnutella and also support Gnutella2.

P2P technology indicates that the Internet revolution is unstoppable. Napster’s innovative indeed made history and finally stopped, but much more powerful successor. Some P2P protocols with an extensive network of today include BitTorrent, eDonkey, and Gnutella.

Blocking file sharing is done from the ISP and backbone level is not always effective, from the business side of the music industry and possibly other media, began to adapt technologies to transform the workings of royalty/ license.

 

Kinds of Virtualization

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Here, we’ll explain a little about some of the methods that implement virtualization on x86 architecture.

Hypervisor Mode

X86 processor family has several levels of protection which is also known as the Ring. This is where the program code is executed. Ring-0 has the highest privilege level, and in the ring is usually the operating system kernel is located. The code that runs in Ring-0 can be said to be running in the system environment, the kernel mode or supervisor mode. For codes other programs such as applications that run inside the operating system, working in the ring that has a smaller priority, usually in the Ring-3.

With this fact, emerged the so-called hypervisor virtualization. Where a program known as a hypervisor (also commonly known as type 1 Virtual Machine Monitor, or VMM) running directly on the hardware level of the host system in Ring-0. The task of the hypervisor is to handle the resource and the allocation of memory for the virtual machine (guest OS), apart from providing high-level interface for administration and monitoring tools.

Clearly, with the hypervisor occupies the Ring-0 from the CPU / processor, then the kernel of the guest OS should run on any CPU in the ring that has a lower priority. Unfortunately, almost all of the operating system kernels are designed explicitly to run in Ring-0. This is because the simple reason that they need to perform tasks that usually exists only in the Ring-O.

Paravirtualization

In the paravirtualization, the guest kernel of the operating system can be modified specifically to run on the hypervisor. It is usually associated with replacing all the important operations (privileges) that will run in Ring-0 from the CPU, by way of making calls to the hypervisor (called hypercall). Consequently, the hypervisor will perform the operation directly to the hardware that to replace the guest OS kernel.

Usually, this is only limited to the open source operating systems like Linux, which can easily be modified freely, or for modifications to a proprietary OS which already allowed the copyright holder, to be compatible with a particular hypervisor. The advantages of OS modification is the ability to direct communication with a hypervisor guest OS, which leads to higher performance levels than other virtualization approaches.

Full Virtualization

Virtualization enables support for the guest OS is not modified, refer to the OS kernel is not tampered with in order to run in the hypervisor. In other words, he can still have access as well as the hypervisor that runs in Ring-0 from the CPU.

In this scenario, the hypervisor will emulate the CPU to run the guest OS kernel is not modified. Unfortunately, this emulation process requires both time and system resources overall, which leads to performance that is not too good compared with paravirtualization model.

Hardware Virtualization

This method implements tours virtualization directly into the processor. For now, be dominated by a processor made by Intel and AMD. For AMD, it refers to the implementation of virtualization into the processor with the name of AMD-V. For Intel is named as Intel VT. Virtualization technologies will provide the necessary extension to run the guest OS (virtual machine) is not modified, without the need for emulation of the CPU/processor.

More simply, the processors with hardware virtualization features will provide additional privileged mode on the Ring-0, where the hypervisor would run and make the Ring-0 is available for use by the guest OS virtual machine that is not modified.