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Will BitTorrent harm my computer?

Will using BitTorrent harm my computer, and if so and under what conditions
will it?

BitTorrent itself is highly unlikely to harm your computer.

However what you download using BitTorrent – well, that’s a
different story. Some caution is called for.

And I know some of you are asking … “what’s a BitTorrent?”

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Traditionally, when you download a file from the internet, it’s really just
copying a file from one computer to another. Typically that means you’re
copying a file from some centralized server to your computer:

Single computer downloading from a central server

The “problems” with that approach include the fact that there’s a central
server – if it goes down, for example, you can’t download the file. Another
problem is that everyone is picking up the file from one place – that means
that for a popular download, that server better have a very fast or “high
bandwidth” connection to the internet that all people downloading at the same
time can share:

Multiple computers downloading from a central server

BitTorrent is one implementation of something called “peer to peer” file
sharing. Rather than downloading from a single central server, the download is
divided into pieces, and those pieces are downloaded from different
computers:

Single computer downloading from multiple peers

Note that we no longer think of those computers serving up the files as
“servers”. Rather, they’re your peers – other computers pretty much just like
yours. Hence the term “peer-to-peer”.

“The problem is not with the technology, but with how
it’s frequently used.”

By copying peer-to-peer the bandwidth used is spread out across many
different paths through the internet. Peer #1 might be down the street, peer #2
might be across the country, and peer #3 might be across the planet. Each will
serve up parts of the file as fast as they can, and your BitTorrent client
patches those pieces together as they arrive.

Now, how did those peers all get the file in the first place? The same way
you’re downloading it. And how did they start serving up pieces of the file? By
running the BitTorrent client. One important aspect of peer-to-peer file
sharing is that as soon as you’ve downloaded even a piece of a file, your file
sharing client can then make that piece available for someone else to download
from you. Your computer becomes one of the peers that can serve the file to
others.

A more accurate diagram of peer-to-peer file sharing is this:

A collection of file sharing peers

In this diagram every computer interested in sharing or downloading a
particular file is, effectively, connected to every other interested in that
same file, sometimes called a “swarm”. If a computer doesn’t have all the parts
of the file, it keeps asking other peers for the missing pieces until it has
the complete copy. It can then remain in the swarm, making all the pieces
available to any other peers that ask.

So that, in a nutshell, is BitTorrent, and peer-to-peer file sharing. In and
of itself, it’s just a different technology to download files, and there’s
absolutely nothing inherently wrong with that. BitTorrent itself will not harm
your computer in any way.

But there is a problem.

The problem is not with the technology, but with how it’s frequently
used.

As you can see from that last diagram, there is no single authoritative site
for a particular file being shared on a peer-to-peer network. If you take out
any one of the computers in the network, the rest can continue to share and
copy the files quite happily.

That means it’s extremely difficult to stop a file from being
shared.

It also means that it’s very difficult to track down all the sites sharing a
file.

In turn, that means that sharing illegal or pirated copies of files is much,
much easier, because it’s much less likely that any single sharer will be
tracked down and prosecuted. Possible? Yes. But definitely more difficult.

So, many peer-to-peer networks have a lot of illegal content.

Even so, downloading illegal copies of legitimate software, music or videos
won’t harm your computer. It’s wrong, but it won’t harm you.

Spyware and viruses, on the other hand, will.

What many hackers and malware creators have realized is that there are a lot
of people downloading illegal software from peer-to-peer networks. Since
there’s almost no accountability for what gets placed on a peer-to-peer
network, it’s trivial for them to put up lucrative files that have been
infested with malware. For example a file sharing network might offer
“Microsoft Office”, and it might even be a copy of the latest and greatest copy
of Office. But it’s quite possible, perhaps even likely, that the person that
first shared that copy added to it spyware or viruses in the hopes that people
would be tempted by a free copy of an expensive product only to install much
more than they bargained for.

And that’s what will harm your computer – the malware that often
accompanies “free” software available on peer-to-peer networks.

Because, let’s face it, who would you complain to if you find that your
latest free download infected your machine with spyware? As I said, there’s no
accountability, and nowhere to turn.

Besides the moral and ethical reasons for not downloading illegal software,
the risk of infection is a very practical reason to stay legit.

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22 comments on “Will BitTorrent harm my computer?”

  1. If the receiving computer has a current and active firewall, antivirus, antispyware, etc. is the risk of becoming infected greater because more pieces have to be scanned? How does this compare to scanning an entire file from a single source?

    Reply
  2. I would consider it roughly equivalent. It depends somewhat on the anti-virus program’s architecture and configuration. There’s a theoretical hole if a virus spans two different pieces that are downloaded separately. It’s a low probability to begin with, and some virus scanners may handle it anyway.

    Anti-spyware scans typically kick in when (or after) you’ve actually run the downloaded file, so that’s after the download’s done regardless of how you got the file.

    Firewall doesn’t actually apply in this situation.

    Reply
  3. The viruses/spyware myth is perpetuated by organisations who want to control what you can and can’t do with your pc and everything on it.
    (MPAA, RIAA and others)

    If you have installed a good
    – Antivirus (eg Bitdefender/kapersky)
    – Firewall (not just windows xp firewall)
    – Anti-spyware (eg Webroot Spysweeper)
    then any potential harm is minimised.

    In 10 years of downloading everything from p2p, I have had less than 5 viruses and 25 spyware. All of them detected and removed automatically within seconds my software before anything happens.

    The trick is not to be stupid, read other peoples comments where possible to avoid downloading something already flagged as bad.

    If retards supported and authorised by the MPAA/RIAA would stop posting fake/corrupt/spyware ridden programs on p2p then the world would be a better place. 😉

    Reply
  4. no it wont harm because the only way to get a virus us for the contents downloaded from the torrent to be packed with a virus.

    torrents are not like gnutella,napster or limewire where you share directly.

    a torrent you have to pack the files and assign a hash to the files .

    and even if someone packs a virus it will be caught by someone and then reported to the tracker and they will remove the torrent and possibly ban the poster

    Reply
  5. Hi i want to destroy someones computer they have really given me a problem. They refused to pay my money. so I kindly ask you to assist me out i already have a backup of all his files as soon as he pays will return his computer normal

    Reply
  6. I’m terrible with technology. I’ve never bit-torrented anything before, but I’m curious. If I bittorrent virus-corrupted files onto one computer, then transfer those files to another computer via flash drive, would that corrupt the second computer with the virus?

    It depends on a number of things, but yes, in short, it’s possible. Avoid viruses, period.

    Leo
    14-Sep-2009

    Reply
  7. I used both Bit Torrent and Limewire for a little over 2 years but will never use them again. I was hit with a Trojan virus that cost me $218! Never again!

    Reply
  8. While I don’t recommend sharing/downloading pirated software, P2P file sharing is a great way to find obscure music & even old TV shows.
    I’ve been using utorrent for a while & have never downloaded a virus. Like Peter A. states above, If you read the comments & ratings from people who have already downloaded the file you want, you should have no issues. I also use Avast antivirus & Malwarebites Antimalware.

    Reply
  9. for those who a interested–

    try using virtual machine for your downloads. thats what i do. then if you get a virus, you can just delet the virtual machine and start again. viruses in virtual machine cant harm your computer.

    Before assuming that a VM is that safe, I think you’ll want to read this: Does using a virtual machine keep me safer? – it can help, but there are still real risks.

    Leo
    18-Jan-2011

    Reply
  10. viruses and legitimate issues are one story, but lately i learnt another stark truth about torrents that it shortens the life span of ur hard disk. But still it is an undisputed issue.

    Bogus. Torrents don’t shorten your disks life.

    Leo
    30-Nov-2011
    Reply
  11. Leo,
    Gotta tell you that this is the first time that I have read an explanation for a computer question that I can actually understand. The words as well as the diagrams were very well put together and I do appreciate this. You see, I am the quintessential computer moron. Thank you very much for your clear, easy to understand explanation. Happy Holidays.

    Reply
  12. Leo, in your opinion, is WebRoot SecureAnywhere or similar virus detection software an acceptable defense against torrent-triggered malware?

    Reply
  13. @John
    Torrent triggered malware is no different than any other kind of malware which you can get from running a virus infected program. These kinds of virus are 100% preventable if you don’t run any programs or download files which are not from reputable sources.

    Reply
  14. If I’m using bit torrent to just watch movies and t.v. shows, and I have Kaspersky will I still be at risk for catching viruses? Note: I’m not using it to download software.

    Reply
  15. @Michael
    If you don’t download programs, using BitTorrent would not put you in danger of catching a virus. However, if you use it to download copyrighted materials, you would be at risk of getting caught and paying a heavy fine. It happened to a friend’s daughter.

    Reply

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