Re: [Sheflug] webmin upgrade, MD5

[Richard Fletcher <xxxxx [at] xxxxxxxxxxxxxxxxxx>]

On Friday 02 August 2002 11:20 am, stephen.tozer-loft [at] sth.nhs.uk wrote:
> i use webmin a lot and felt like upgrading from my version 0.94 to the
> latest 0.99.  I downloaded the RPM from a recommended mirror (i'm running
> rh7.1) but however i try to install it i get the following:
>
> warning: /etc/pam.d/webmin saved as /etc/pam.d/webmin.rpmorig
> error: unpacking of archive failed on file
> /usr/libexec/webmin/apache/allmanual_form.cgi: cpio: MD5 sum mismatch
>
>
> the warning is just that, but what can i do about an MD5 sum mismatch? i
> don't think the rpm is corrupt:  I tried downloading the version 0.98 rpm
> and that did the same thing.
>

Though its highly unlikely it is possible to download a file which is 
corrupted on the way.  Software will check that each packet is consistent, 
but not what was sent. For example if I take a string of five zeros and ones
10101
say and then add a checkdigit designed to make the string sum to zero in 
moduluis 2 I would have the string
101011 (1+1+1+1=4=2*2+0  therefore sums to 0 mod 2)
now assume an error crept in during transmission and what is actually recieved 
is
111011 (1+1+1+1+1=5=2*2+1 therefore sums to 1 mod 2) 
Thus we know there has been an error.
Unfortunately if two errors were made we have a zero sum again and we think 
its okay even though it isn't, 000011 for instance. 
The error checking in your computer is better but if you have a dodgy line 
perhaps the numbers of error's are high enough to occasionaly send a packet 
which looks like the inteded packet but is mangled. If this is true and if 
the checksum method is not the same as md5 sum then this could be the 
problem.

But it is _very_ unlikely that it would have happened twice. I suppose a 
symptom would be a really slow transfer rate, as packets are constantly 
rejected and replacements are requested. Other downloads would be buggered 
too. 

Maybe not much help but interesting all the same

-- 
.oOO-Richard-Sheffield-UK-OOo.

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