The Pirate Bay, which calls itself "the world's largest telecom sharing website", is a website dedicated to storing, classifying and searching telecom resources, and it also runs the world's largest BTTracker server. On June 5438+065438+1October 15, 2008, The Pirate Bay announced that its scale had reached 25 million independent peers. Note that it is not a seed. Peer can be regarded as the actual number of users (computers) participating in the Pirate Bay "Sharing Plan". As of February 2009, the number of registered users of The Pirate Bay has reached 4 million. But it seems that the reputation is not very good. The Los Angeles Times called it the world's largest illegal download assistant (accomplice? ) one. The Pirate Bay was formally established in June 5438 +2004 10, which not only had brilliant achievements, but also was full of troubles. According to the records, there are as many as 34 cases against The Pirate Bay, including 2 1 case involving music industry, 9 cases involving film industry and 4 cases involving game industry. 2009 became the most intense year of struggle. On April 7th, 2009, the court in Stockholm, Sweden, sentenced four founders of The Pirate Bay 1 year to imprisonment and fined about 30 million Swedish kronor for copyright infringement. What happened afterwards made people feel that the "deadline" of BT had finally arrived. 1 17 10/7, The Pirate Bay decided to shut down their tracker server permanently. 12 At the beginning of June, Mininova, the world's second largest BT service website, deleted the BT trackers of most illegal files on the website. Mininova said that in order to avoid paying the fine, they had no choice but to delete the BT Tracker of all infringing documents. Some people say that an era is over, and the Motion Picture Association of America (Motion Picture Association of America) and RIAA (Recording Industry Association of America) have become the winners in this struggle. On the surface, it is true. In this struggle, what the Motion Picture Association of America and RIAA want to "get rid of" is the BT tracker server, and they have already done it.
Maybe an era is over, but is the BT era really over? The answer is no, the Motion Picture Association of America and RIAA "removed" the BT Tracker server, blocking the "life gate" of the current BT working mode. However, with the introduction of new technology, BT tracker has become unimportant or even redundant for BT sharing. Things sometimes turn out to be like a joke, and this time the joke was played on the Motion Picture Association of America and RIAA. Why is this happening? To understand this, we must first sort out the implementation of BT sharing.
How do users download files through BT? The basic process should be like this: first find the Torrent file, and then download the client software with BT to open the file. Third, for users, it only takes time to wait. As for the client software, it will automatically connect to the Tracker server according to the URL in the Torrent file, and receive the URL list of other people who are downloading the file from it. Next, the software will contact the websites on the list one by one and get file fragments from them until the whole download is completed. It is not difficult to see from the whole process that the BT Tracker server is a central node where any client can find a "companion"-as long as everyone else is downloading or sharing the same file. Therefore, the Motion Picture Association of America and RIAA are eyeing BT Tracker, because it is almost impossible to eliminate all Torrent files, but it is entirely possible to eliminate BT Tracker servers through some "efforts". The lawsuit was won and an era was over. We might as well call it the BT 1.0 era. The fatal disadvantage of BT 1.0 era is that it has a central node, namely BTTracker server. However, losing the case does not mean the end of the whole BT era. A new era has quietly begun, which we can call BT2.0 era.
In the era of BT2.0, Magnet has become the future development direction of BT. Can magnets really save BT? After the author personally tried and supported the magnet URI, The Pirate Bay seems to be reborn, and the download speed is not getting slower and slower. On the contrary, the speed performance is satisfactory. Crucially, Magnet doesn't need to track servers or seed files. It only needs a string of characters to download files. The LOGO of the Pirate Bay, the "totem" of the future BT, and the BT resources on the Pirate Bay have joined the download mode of magnets-excerpted from the blog post entitled "The most stable tracking in the world" in the Pirate Bay. The article mentioned: "With the continuous maturity of DHT+ PEX technology, it becomes easy to find peers and coordinate communication, and the Tracker server becomes less important. The article also said that the server is now placed in a museum. It seems that shutting down the tracker server is planned. Everything is under control? Tracker server and BT Seed will be retired soon and replaced by DHT+ PEX network and Magnet Link. DHT network is distributed, there is no problem of "unplugging", and the magnet link is just a string of characters, so Torrent file is no longer needed.
Here are three key words: DHT, PEX and Magnet Link, which are the core of future BT. Let's talk about what functions they can achieve first.
DHT: In 2002, two professors of new york University, Petar Maymounkov and David Mazières, published a paper and proposed a truly decentralized "peer-to-peer" download model, which they called Kademlia method. In 2005, BT software began to introduce this technology, which is called DHT (Distributed Hash Table) in BT. DHT is a distributed storage method. The function of DHT is to find the peer that is downloading (uploading) the same file as this machine. Of course, this process does not depend on the Tracker server. Each client in DHT network is responsible for routing and storing a small part of data in a small range, thus realizing the addressing and storage of the whole DHT network. This information acquisition method ensures that there is no single center in the whole network. Even if a node is offline, it can still get files from other nodes, so you don't need the Tracker server to tell you the location of other nodes.
PEX: the abbreviation of peer-to-peer exchange, which can be understood as "node information exchange". Although DHT solves the problem of decentralization, PEX is necessary to achieve efficient addressing without a "central coordinator". The functions provided by PEX are somewhat similar to those of previous tracking servers, but they work in very different ways. We can give an example to illustrate this point. Xiao Zhao is in Class A, and she doesn't know Xiao He of Class B or Xiao Wen of Class C, but Xiao Zhao knows Xiao Wang of Class B, and Xiao Wang may also know Xiao Wen of Class C, or Xiao Wang only knows Xiao He of Class B, but Xiao He knows Xiao Wen of Class C, and Xiao Wen knows all his classmates. Therefore, in any case, Xiao Zhao can expand his network "infinitely".
Magnet link: Some netizens call it flux linkage. DHT+ PEX solves the problem of BT "addressing", but how to tell BT clients what they are looking for is another problem. The content contained in the Torrent file is the characteristic information of the file that the user really wants to download, or it is called "electronic fingerprint". BT client knows what to look for and how to find it, so it realizes downloading and uploading in P2P mode. In the past, BT customers learned what they were looking for through Torrent files. Now, the "electronic fingerprint" of the file is not stored in Torrent, but in Magnetlinks. Magnet:? XT = URN: BTIH: CBCDEFGHIKNOPQRSTUVWXYZ12345678 The above is a file I intend to download, Microsoft iSCSI initiator. According to the previous method, we need to download its Torrent file first and then download the file itself. However, in the new mode, we don't need to download the seed file, only need to know its magnet URI, a resource location information, and nothing else. As long as you tell the download software this address, the software will automatically start downloading. Let's break down this address: magnet: protocol name. XT: the abbreviation of exacttopic, which stands for resource anchor point. BTIH(BitTorrent Info Hash) indicates the name of the hash method, and SHA 1 and MD5 can also be used here. This value is the identifier of the file and is essential. Dn: the abbreviation of displayname, which represents the file name displayed to the user. This is a choice. Tr: the abbreviation of tracker, indicating the address of the tracker server. This is an option that does not appear in this example. In order to simplify the above example, only magnets are needed: Xt = urn: btih: dbdefghijklmnopsrstuvwxyz12345678 is enough, and it will be more convenient to use if dn (display name) is added. Needless to say, the benefits of MagnetLink include at least two points: the reliability of the network is greatly enhanced; There is no risk of being "unplugged". Because there is no so-called central node, review will become more difficult, and the problem of "single point failure" will not exist. In addition, MagnetURI is just a string, which is very easy to spread and cannot be banned at all. Therefore, it will be the general trend for magnet URI to replace tracker mode, and it will become the mainstream BT download mode sooner or later.
Careful netizens may have seen a problem in the DHT+PEX+ magnet link mode-how did the BT client "take the first step"? To apply the example used when introducing PEX, how did Xiao Zhao "join" Class A? This is really a problem. To solve this problem, we still need a boots trap node, but the role of this server is different from that of Tracker. It is only responsible for admitting Xiao Zhao into Class A. When Xiao Zhao "catches up" with the students in Class A, this server is of little use. Boots trap nodes can be operated independently by different BT client vendors or jointly used by several companies. In short, it is decentralization. As long as a form is built into the client software, the client will have many entrances to choose from. Having said that, what is the performance of the magnet? Whether it's a mule or a horse, you have to pull it out for a walk. So I found the BT client μTorrent that already supports Magnet. μTorrent is one of many BT clients. During the installation, we can see that it already supports the magnet URIs. The speed of μTorrent downloading BT resources is 144.4KB/s/s, and the resources we downloaded are from The Pirate Bay, so the opposite resources are all from abroad. If Magnet is completely "localized" and the number of users reaches a certain scale, its performance should be completely comparable to the traditional BT download method. Seeing this, I believe you have understood why The Pirate Bay obediently shut down their BT tracker server. It seems that the Motion Picture Association of America and RIAA won the first round of the Pirate Bay, but how to deal with the DHT+PEX+ magnet link mode should be a headache. In the movie "Hide and Seek", the police fought guerrilla warfare with "pirates". The BTTracker server in The Pirate Bay had a similar experience-moving from one country to another and hiding in different IDC, but the copyright organization persisted and finally succeeded. Later, at the same time, we happened to hear three voices. The copyright organization said we won. The pirate bay said, we won't play with you; The onlookers said that BT was fine. What have those two guys been doing these years? There is almost no cost for netizens to abandon the tracker mode and use magnets instead. They only need to upgrade their current BT software, and even their operating habits will not change, because you don't need to change other BT software. In China, bitspirit and Bitcomet have started to support Magnet. So, you may have entered the BT2.0 era, but you just don't know it yet. "We don't provide physical download resources, all resources are spontaneously uploaded by netizens ..." I believe you will often hear similar excuses. This sentence seems very reasonable from a technical point of view, there is no loophole, but it feels a little sophistry. Things are constantly developing, which leads to the lack of supervision. When the supervision means are more and more perfect, things may move forward again, leading to the backwardness of supervision means again. The new BT sharing method "decomposes" the functions provided by the traditional Tracker server. All BT users become part of the tracker server, and the core disappears. In this case, who should the copyright organization swing the anti-piracy stick at?