Cygwin DLLs being modified somehow?

Michael DePaulo
Mon Feb 23 14:04:00 GMT 2015

On Sun, Feb 22, 2015 at 10:31 PM, René Berber <> wrote:
> On 2/22/2015 7:53 PM, Michael DePaulo wrote:
>> I am seeing very weird behavior and I am hoping that someone can explain it.
>> This happens on 2 different machines. My personal Windows 10 64-bit
>> machine, and a Windows 7 64-bit VM hosted by the X2Go project on
>> another continent.
>> It seems to be happening to multiple DLLs, but I will list one example below.
>> I install 32-bit Cygwin with the 2.870 installer
>> libopenssl100 is one of the packages that gets installed. It is at
>> version. 1.0.1k-1
>> /bin/cygcrypto-1.0.0.dll always appears to be 1,820,199 bytes, and it
>> always appears to be last modified on 1/8/2015 20:30 UTC.
>> When I extract it from the tarball:
>> Its md5sum is:
>> c79b900428d91e5882c24bbb6bc36969
>> And its sha256sum is:
>> 53376a3d69be996cb71abda41b7cc6bea7a599b027fe819323fafc3c433b7767
>> Yet on both systems, once installed, its m5sum and sha1sum differ!
> [snip]
> The installation, you may have noticed, always runs rebase at the end.
> There's very little documentation left about rebase, the only one I
> found is in:
> /usr/share/doc/Cygwin/_autorebase.README
> --
> René Berber

Thank you René and Andrey.

I found this too:

However, this leads to a another question. On the X2Go project, we
compile nxproxy, a 3rd-party piece of software that we are now
maintaining, against Cygwin. We also recompile Cygwin OpenSSH with an
X2Go-compatibility patch applied and with Kerberos support disabled.
(We make sure to comply with the GPL.)
So far we have just been distributing these .exe files and .dll
files[1] in the X2Go Client directory (C:\Program Files
(x86)\x2goclient\), which also contains regular win32 code. We do not
run the Cygwin installer or call rebase. We use NSIS for our
installer, and it simply copies the files.

So my question is: Is there a better way to distribute/install these 2 programs?
(We want to make X2Go Client for Windows easy to install, even for
people who have never used Cygwin. We also want to update/upgrade
these files in between X2Go Client maintenance releases (like 4.0.3.x)
only when there is a need to, such as a security update.)

Also, in the absence of a doing things differently, should we just
distribute the original .exe and .dll files from the cygwin binary


original cygwin files:
sh.exe (renamed from dash.exe)

recompiled OpenSSH:


Problem reports:
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