2.2:    Obtaining & verifying the ISO

Introduction

This page provides guidance if you intend to download an ISO and burn your own CD or DVD instead of buying it from the Mepis Store.

Downloading MEPIS Linux

Here are a few considerations to keep in mind:

• The first day or two after new ISO is released, a particular mirror (a web site that is an exact copy of another site) may not have it. Check other mirrors until you find the version you are looking for, then click the filename to download it. These files are usually very large, so plan to wait for some time (depending on your machine, connection and web traffic).
• Sometimes an ISO may be incomplete. This is caused by the mirror attempting to grab the ISO before it has completely uploaded to their source site. If this happens, the ISO may be unusually small or it may give cloop errors when a CD is booted.
• If different mirrors offer ISOs of different sizes, the larger ISO is probably correct. If a mirror site has a bad ISO file, it will probably be replaced during the next automatic update at that site, usually done once per day.
• Make sure to download the md5sum file (see below) from the same directory as the ISO file. It will have the same filename but the extension will be .md5sum. Make certain that you put the MD5sum file in the same directory as the ISO file.
• If the md5sum does not match, you could try one of the following options:
  • Copy the ISO with a bad checksum to a download folder used by a BitTorrent program (see Section 8.1), then restart the download using a BitTorrent program. Many BitTorrent programs will find the file already on your hard disk and patch it by downloading only the missing or damaged portions.
  • Try a different mirror site
  • Download the ISO again

Downloading MEPIS Linux via BitTorrent

BitTorrent file sharing (see also Section 8.1) provides an internet protocol for efficient mass transfer of data. It decentralizes the transfer in such a way as to utilize good bandwith connections and to minimize strain on low-bandwith connections. An added benefit is that most, if not all, BitTorrent clients perform error checking during the download process, so there is no need to do a separate md5sum check after your download is complete. It has already been done!

Volunteers from mepis.org and mepislovers.org usually have a seeded BitTorrent of the latest MEPIS Linux ISO registered at linuxtracker.org within 24 hours of its official release. Bit-torrent downloads may be somewhat slow following a major release.

If you are not familiar with BitTorrents, see the Links and Guides section for sources of more information.

If you are downloading a MEPIS Linux ISO via BitTorrent, you can skip the next section about verifying the md5sum and go directly to the next page:

2.3: Burning the CD

Verifying the md5sum

After you have downloaded an ISO, the next step is to check its md5sum against the official one. The md5sum is the result of a complex calculation on the contents of a file: the outcome is a unique string. It will be identical to the official md5sum if your copy is authentic. The following steps will let you verify the integrity of the downloaded ISO on any OS platform:

md5sum: Windows

Windows users should download a tool called md5summer (link below):

1. Download the self-extracting .exe file. Double-click it to put 2 files in the current directory: md5summer.exe and md5summer.md5
2. Run md5summer.exe, respond “yes” to associate extension .md5 with md5summer program.
3. Now you can either double-click on the .md5 file and the program will check the md5 sum automatically, or from inside the md5summer program you can select the location of the .ISO and .md5 files, and then click “verify sums” and select the .md5 file you want to check.

md5sum: Linux

Method 1. The easiest way to check an ISO's integrity in Linux is to use K3b, the CD/DVD burner that is installed with MEPIS Linux 7.0. When you first load an ISO file into K3b, it will automatically calculate and display the md5sum. The final five numbers should match those in the md5sum file you downloaded with the ISO.

Method 2. If not using K3b, open up a console/terminal and type:

cd /directoryname

where directoryname indicates the location of the ISO and md5sum files. Then type:

md5sum filename.ISO

Be sure to replace filename with the actual filename.

Compare the number obtained by this calculation with the md5sum file downloaded from official site. If they are identical, your copy is identical to the official release.

md5sum: Mac

Mac users need to open up a console/terminal and change into the directory with the ISO and md5sum files. Then issue this command:

md5 -c filename.md5sum

Be sure to replace filename with the actual filename.

Links and Guides

• Wikipedia: Bit-Torrent: http://en.wikipedia.org/wiki/Bit_torrent
• MEPIS Wiki: Using KTorrent: http://www.mepis.org/docs/en/index.php/KTorrent
• md5summer download page: http://sourceforge.net/projects/md5summer/
• Wikipedia: md5sum: http://en.wikipedia.org/wiki/Md5sum

---