Red Hat Knowledgebase

To verify that your downloaded ISO images are intact prior to performing an installation, use a program to calculate the md5sum of the ISO file. If you do not have another Red Hat Enterprise Linux machine available to test the ISOs, md5sum programs for other operating systems can be found through a web search. If you have a Red Hat Enterprise Linux computer available, you can use the included md5sum program. Simply type

$ md5sum <filename.iso>

at a shell prompt, replacing "filename.iso" with the name of your ISO file. When the command completes, it will return an alphanumeric string that is the MD5 checksum of the file. Compare that string to the one that can be found in the Red Hat Network (RHN) ISO download section. Here's how to find the MD5 checksums on RHN:

• Log in to your RHN account at http://rhn.redhat.com.
  
• Click on the Channels tab at the top of the page
  
• Click Easy ISOs on the left hand side of the page
  
• Click on the Channel name of the software you want to check. Here you will find links to the ISOs and each ISO's MD5 checksum.

If the output from md5sum does not match the value on the RHN page, the ISO file is corrupted and will need to be downloaded again. If you are having difficulty with timeouts while downloading ISO files, please see additional articles on resolving dropped connections during ISO downloads.

You can also test checksum integrity of any Red Hat Enterprise Linux CD by typing linux mediacheck at the installation boot: prompt after booting off the first install disc. Please see additional articles on testing the integrity of install CDs for more information.