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I downloaded the Limbo from ftp.redhat.com. The last file is called MD5SUm(given below). What is the purpose of MD5sum file?
66f7308e17713b32147d469741a81992 limbo-i386-disc1.iso
6fcf44fb96460bc469e1d75e862d721a limbo-i386-disc2.iso
6818661ba15c2a0529d03ceeb12b77a0 limbo-i386-disc3.iso
f06fe629dc4b49381fea01d9c0427139 limbo-i386-disc4.iso
94e456b728297d75037f5e6a9f0f1f99 limbo-i386-disc5.iso
Thanks a lot
 
Saloon Keeper
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MD5 is used as an authentication method. The RPM file is passed through a utility that calculates an MD5 digest (summary) which is a hash of the RPM. If you reapply MD5 to the downloaded RPM and the recalculated digest disagrees with the supplied MD5, it indicates that someone has tampered with the RPM (e.g. substituted a trojan copy).
The RPM utility has the ability to apply the MD5sum as part of the install/verify process, thus making it harder for "bad guys" to corrupt your system.
An especially useful feature is that the -V option of RPM can verify the current state of your system against the package's original MD5s in order to hilight files which have been altered (it also does a number of other tests to further determine if/how a change occurred).
You can do "rpm -Va" to check out EVERY package in the system (a == "all"). Be prepared to wait a while, and it's a good idea to log to disk, since a lot of /dev files will indicate changes just because of the way they get installed.
Tripwire is another product that uses MD5s to test system integrity, except that here you can also monitor ongoing (post-install) changes to files and files that are not managed by RPM.
 
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Following link will help if you want to verify the downloaded images are actually perfect in all respects. Its very common that you will get wrong/partial versions of .iso's downloaded and OS installation will crash half way through.
How To Check MD5sums On A Linux Iso Image
Ashok.
 
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