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Re: transfer speed data

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On Wed, Dec 23, 2020 at 09:56:01AM +0800, Jeremy Ardley wrote:
>Having said that, scp and ssh are affected by the encryption algorithm. The
>fastest one at the moment is blowfish and it's possible to get up to 50 MB/s on
>a gig lan.

That's pretty ancient advice. The fastest on most modern x86 CPUs with 
AES-NI instructions is aes128-gcm@openssh.com. Without AES-NI your 
fastest may be chacha20-poly1305@openssh.com. The default is chacha20, 
which is fast enough in most cases that it doesn't matter, but worth 
testing & reconfiguring in cases where it does. Blowfish isn't supported 
in the latest versions of ssh, and even before it was dropped it was 
much slower than hardware-accelerated AES. It also never got an 
authenticated encryption mode IIRC, so it had additional MAC overhead 
that the more modern modes do not.

The following are on a mid-range Ryzen machine running to localhost, to 
take the network out of the equation, and are copying a sparse 1G file 
to /dev/null so there's no disk I/O; either of these algorithms will 
easily max out a gigabit connection if the disks are fast enough.

> scp -o Ciphers=aes128-gcm@openssh.com testfil localhost:/dev/null
testfil                               100% 1024MB 864.3MB/s   00:01    
> scp -o Ciphers=chacha20-poly1305@openssh.com testfil localhost:/dev/null
testfil                               100% 1024MB 475.1MB/s   00:02

For comparison, here's stretch (still supported blowfish) on a much lower 
power intel CPU (i3-7100U):

$ scp -o Ciphers=chacha20-poly1305@openssh.com testfil localhost:/dev/null
testfil                               100% 1024MB 167.7MB/s   00:06    
$ scp -o Ciphers=aes128-gcm@openssh.com testfil localhost:/dev/null
testfil                               100% 1024MB 507.5MB/s   00:02    
$ scp -o Ciphers=blowfish-cbc testfil localhost:/dev/null
testfil                               100% 1024MB  77.8MB/s   00:13    

(see how terrible blowfish is, and how the AES-NI acceleration leads to 
AES tremendously outperforming CHACHA20?)

here's an almost 10 year old non-AES-NI desktop cpu:

$ scp -o Ciphers=aes128-gcm@openssh.com testfil localhost:/dev/null
testfil                               100% 1024MB 224.7MB/s   00:04    
$ scp -o Ciphers=chacha20-poly1305@openssh.com testfil localhost:/dev/null
testfil                               100% 1024MB 184.9MB/s   00:05    

Note that AES & CHACHA20 are much closer in performance, but AES is 
still faster. Note also that either can still max out gigabit ethernet.

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transfer speed data mick crane <mick.crane@gmail.com> - 2020-12-23 02:00 +0100
  Re: transfer speed data Bob Weber <bobrweber@gmail.com> - 2020-12-23 02:40 +0100
  Re: transfer speed data Georgi Naplatanov <gosho@oles.biz> - 2020-12-23 02:50 +0100
  Re: transfer speed data Jeremy Ardley <jeremy@ardley.org> - 2020-12-23 02:50 +0100
    Re: transfer speed data Jeremy Ardley <jeremy@ardley.org> - 2020-12-23 03:00 +0100
      Re: transfer speed data Michael Stone <mstone@debian.org> - 2020-12-23 16:10 +0100
        Re: transfer speed data Jeremy Ardley <jeremy@ardley.org> - 2020-12-23 16:40 +0100
          Re: transfer speed data Michael Stone <mstone@debian.org> - 2020-12-23 17:00 +0100
            Re: transfer speed data Jeremy Ardley <jeremy@ardley.org> - 2020-12-23 17:20 +0100
              Re: transfer speed data Michael Stone <mstone@debian.org> - 2020-12-23 18:40 +0100
  Re: transfer speed data Andy Smith <andy@strugglers.net> - 2020-12-23 05:00 +0100
    Re: transfer speed data Nicolas George <george@nsup.org> - 2020-12-23 11:00 +0100
      Re: transfer speed data Andrei POPESCU <andreimpopescu@gmail.com> - 2020-12-23 15:50 +0100
        Re: transfer speed data Nicolas George <george@nsup.org> - 2020-12-23 17:10 +0100
        Re: transfer speed data David Wright <deblis@lionunicorn.co.uk> - 2020-12-23 18:50 +0100
          Re: transfer speed data Andrei POPESCU <andreimpopescu@gmail.com> - 2020-12-23 19:20 +0100
            Re: transfer speed data David Wright <deblis@lionunicorn.co.uk> - 2020-12-24 02:30 +0100
              Re: transfer speed data Andrei POPESCU <andreimpopescu@gmail.com> - 2020-12-24 10:10 +0100
                Re: transfer speed data Michael Stone <mstone@debian.org> - 2020-12-24 17:10 +0100
      Re: transfer speed data Michael Stone <mstone@debian.org> - 2020-12-23 16:20 +0100
        Re: transfer speed data Nicolas George <george@nsup.org> - 2020-12-23 17:20 +0100
          Re: transfer speed data Michael Stone <mstone@debian.org> - 2020-12-24 17:10 +0100
    Re: transfer speed data deloptes <deloptes@gmail.com> - 2020-12-23 12:20 +0100
  Re: transfer speed data George Shuklin <george.shuklin@gmail.com> - 2020-12-23 23:00 +0100

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