5 ms·

I downloaded the first couple dozen megabytes. It's all nulls. $ od 500megabytefile.tar.gz 0000000 000000 000000 000000 000000 000000 000000 000000 00

by ableal 15y ago

I downloaded the first couple dozen megabytes. It's all nulls. $ od 500megabytefile.tar.gz 0000000 000000 000000 000000 000000 000000 000000 000000 000000 * 27200000 (besides not being a .tar.gz, it's not 500 MB either, it's 512 000 000 bytes = 512 MB, or 488 MiB)

antihero 15y ago
So it can basically compress to something extreme, too.
- charliesome 15y ago
  Exactly. I watched the total traffic tick up in Activity Monitor while downloading it, and it was only 2.2 MB in total.
  - marcf 15y ago
    It is sort of a funny cheat though. A good prank to pull on friends to claim you have a very fast internet connection, but for a company to do this in order to promote their product, it is very dishonest.
skrebbel 15y ago
This also means that opening the tar.gz does not work. Not knowing about the cheat, I'd want to try. My 7-zip choking on the file would make me download again. After the second time, my trust in Singlehop's transfer abilities would be very low - after all, files they send appear to get corrupted.
tomjen3 15y ago
That isn't strange though -- if I were creating a file that I knew would only be used for speed testing, I would make it al nulls too. It is just much easier to find a file that is some exact distance if you create it first.
- randy99 15y ago
  Surely you wouldn't get as greedy as they did though? Nobody would've suspected them if they had've been a little less "cheaty".
- piaskal 15y ago
  I'd use random data to make it hard to compress. You don't know if there won't be some link layer compression along the way.
  - kcbanner 15y ago
    That doesn't really fix the problem, what if that random data happened to compress well? The solution is to not compress anything while downloading.
    - cbr 15y ago
      A large quantity of random data is incredibly unlikely to compress well.
    - gojomo 15y ago
      "Random data' [1] will not compress well [2]. [1] high-entropy in any of the usually-available ways [2] for any compression system actually deployed, as opposed to one contrived to match specifically the 'random' source
- hyperbovine 15y ago
  $ dd if=/dev/random of=nonbullshittestfile bs=1M count=500
  - treo 15y ago
    That would take forever, at least on my system, as I don't really have a lot of entropy available. Just for kicks I have started this when I began writing this reply. And now I have the huge amount of 200 Byte in this test file. So thats about 10 bytes per second. But if you take /dev/urandom you can get quite a bit more. On this system it is about 7Mbyte/s.

by ableal 15y ago

antihero 15y ago

So it can basically compress to something extreme, too.

charliesome 15y ago
Exactly. I watched the total traffic tick up in Activity Monitor while downloading it, and it was only 2.2 MB in total.
- marcf 15y ago
  It is sort of a funny cheat though. A good prank to pull on friends to claim you have a very fast internet connection, but for a company to do this in order to promote their product, it is very dishonest.

skrebbel 15y ago

This also means that opening the tar.gz does not work. Not knowing about the cheat, I'd want to try. My 7-zip choking on the file would make me download again. After the second time, my trust in Singlehop's transfer abilities would be very low - after all, files they send appear to get corrupted.

tomjen3 15y ago

That isn't strange though -- if I were creating a file that I knew would only be used for speed testing, I would make it al nulls too. It is just much easier to find a file that is some exact distance if you create it first.

randy99 15y ago
Surely you wouldn't get as greedy as they did though? Nobody would've suspected them if they had've been a little less "cheaty".
piaskal 15y ago
I'd use random data to make it hard to compress. You don't know if there won't be some link layer compression along the way.
- kcbanner 15y ago
  That doesn't really fix the problem, what if that random data happened to compress well? The solution is to not compress anything while downloading.
  - cbr 15y ago
    A large quantity of random data is incredibly unlikely to compress well.
  - gojomo 15y ago
    "Random data' [1] will not compress well [2]. [1] high-entropy in any of the usually-available ways [2] for any compression system actually deployed, as opposed to one contrived to match specifically the 'random' source
hyperbovine 15y ago
$ dd if=/dev/random of=nonbullshittestfile bs=1M count=500
- treo 15y ago
  That would take forever, at least on my system, as I don't really have a lot of entropy available. Just for kicks I have started this when I began writing this reply. And now I have the huge amount of 200 Byte in this test file. So thats about 10 bytes per second. But if you take /dev/urandom you can get quite a bit more. On this system it is about 7Mbyte/s.