Under what circumstances does scp corrupt data?

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I guess scp does never corrupt data and this is what I expect =)

So, let me explain our problem:
We have an internet server and copy once a week the data to our office.
The server is a debian sarge RC2 with ssh version "OpenSSH_3.8.1p1
Debian-8.sarge.4, OpenSSL 0.9.7e 25 Oct 2004" and the client is woody
with ssh version "OpenSSH_3.4p1 Debian 1:3.4p1-1.woody.3, SSH protocols
1.5/2.0, OpenSSL 0x0090603f"

This all works fine for a long time. A few weeks ago I changed the
compression format of the files from tar.gz to tar.bz2 because of the
less size. And since then there is always data corruption in the same
file. (We copy 12 files)

My first guess was there is a problem with bzip2 so I checked the
version, but it is on both sides "Version 1.0.2, 30-Dec-2001." So I
checked the files with "bzip2 -tvvv <file>" on the server before I
copied and after I copied on the client. On the client the file is
corrupt. I also checked the md5sum and they are different.

Then I read I should check the memory and I did with "memburn" (I have
no local access to the client to use memtest86). Memburn ran for a whole
day but found no problem.

And now I look for the problem at scp... ;)
I call scp with the options "-p -r -B -P 1022"

So, can anyone give me a hint? I'am out of ideas, except going back to
tar.gz... =)
Thank you for your efforts!

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Re: Under what circumstances does scp corrupt data?

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It shouldn't, however if the data is corrupted elsewhere then scp probably
won't detect it.  Corruption on the network should be caught by the MAC
in the ssh protocol.  It's also possible that there's a bug somewhere.

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Can you isolate it to one machine?  ie if you do "scp files*
localhost:/tmp" on each machine, is the corruption present on both or
just one (and if so, which one)?

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Darren Tucker (dtucker at zip.com.au)
GPG key 8FF4FA69 / D9A3 86E9 7EEE AF4B B2D4  37C9 C982 80C7 8FF4 FA69
    Good judgement comes with experience. Unfortunately, the experience
usually comes from bad judgement.

Re: Under what circumstances does scp corrupt data?


thanks for your reply.

It is getting funny. The file that was been corrupted the last 3 times
has been increased by 100MB and was not corrupted this weekend. All
files were copied correctly...

In article <4257ec46$0$14770$5a62ac22@per-qv1-newsreader-
01.iinet.net.au>, dtucker@gate.dodgy.net.au says...
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Works fine on both machines.

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Yeah, I should use something different. This way is not reliable...


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