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userguide:checking_iso_file_integrity [2016/05/02 16:23] Marc tags edited |
userguide:checking_iso_file_integrity [2020/11/26 19:49] (current) Marc |
In simple terms, a //[[https://en.wikipedia.org/wiki/Checksum|checksum]]// or //hash sum// is like a signature or fingerprint that identifies digital data. A copy of a file getting the same computed checksum as the original indicates there is a very high probability the data has not been accidentally altered or corrupted((Security flaws where identified in MD5 and SHA-1 algorithms; they are still useful for error checking, where data tampering is not a primary concern, but the use of stronger hash functions would be desirable.)). | In simple terms, a //[[https://en.wikipedia.org/wiki/Checksum|checksum]]// or //hash sum// is like a signature or fingerprint that identifies digital data. A copy of a file getting the same computed checksum as the original indicates there is a very high probability the data has not been accidentally altered or corrupted((Security flaws where identified in MD5 and SHA-1 algorithms; they are still useful for error checking, where data tampering is not a primary concern, but the use of stronger hash functions would be desirable.)). |
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Checking NethServer's ISO image file takes almost no time and prevents further installation problems. | Checking NethServer's ISO image file takes almost no time and prevents further installation problems. Checksums for the ISOs can be found at the [[https://www.nethserver.org/getting-started-with-nethserver/|download page]]. |
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| The following examples show different ways to check the integrity of a file. |
| Bear in mind the checksums and ISO names mentioned in the examples may differ from the current NethServer release. |
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The following examples show different ways to check the integrity of a file. | |
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===== File Integrity Check from an On-Line Service ===== | ===== File Integrity Check from an On-Line Service ===== |
- Paste the checksum in the appropriate //DownThemAll!// text field\\ | - Paste the checksum in the appropriate //DownThemAll!// text field\\ |
- Start the download | - Start the download |
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| {{ youtube>ochWBOdayK8?medium }}\\ |
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Once the file has been downloaded, //DownThemAll!// will verify it against the hash provided previously. In case of a hash mismatch, a dialog will appear informing you of the failure and will give you the option to retry the download, keep the file, or delete the file. | Once the file has been downloaded, //DownThemAll!// will verify it against the hash provided previously. In case of a hash mismatch, a dialog will appear informing you of the failure and will give you the option to retry the download, keep the file, or delete the file. |
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{{ youtube>ochWBOdayK8?medium }}\\ | {{ :howto:downthemall-hash-mismatch.png |DownThemAll! hash mismatch notification}}\\ |
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---- | ---- |
**7-Zip** (works on Windows)\\ Althought //[[http://www.7-zip.org/|7-Zip]]// is a file archiver, it adds a //CRC, SHA...// context menu entry to ISO image files. This menu allows you to compute the hashes and visually compare them against the original ones. //7-Zip// is //Open Source// software. | **7-Zip** (works on Windows)\\ Althought //[[http://www.7-zip.org/|7-Zip]]// is a file archiver, it adds a //CRC, SHA...// context menu entry to ISO image files. This menu allows you to compute the hashes and visually compare them against the original ones. //7-Zip// is //Open Source// software. |
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{{ :howto:iso-image-file-integrity-check-using-7zip-checksuming-hashing.jpg?direct&200 |7-Zip context menu and hashing}} | {{ :howto:iso-image-file-integrity-check-using-7zip-checksuming-hashing.jpg?direct&420 |7-Zip context menu and hashing}} |
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---- | ---- |
Example: | Example: |
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<code>openssl md5 nethserver-6.7-x86_64.iso</code> | <code>openssl md5 nethserver-7.9.2009-x86_64.iso</code> |
This command will output a computed file hash that can be manually compared against the original one: | This command will output a computed file hash that can be manually compared against the original one: |
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<code>MD5(nethserver-6.7-x86_64.iso) = 695ac8fe87b21501cc438abc411d8f02</code> | <code>MD5(nethserver-7.9.2009-x86_64.iso) = 6a32d2738aafdcf4e124c2822e5c668d</code> |
On **Mac OS X**, you can also use the ''%%md5%%'' command to get the same result: | On **Mac OS X**, you can also use the ''%%md5%%'' command to get the same result: |
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<code>md5 nethserver-6.7-x86_64.iso</code> | <code>md5 nethserver-7.9.2009-x86_64.iso</code> |
On **GNU/Linux**, you can also get the MD5 file hash using the ''%%md5sum%%'' command, | On **GNU/Linux**, you can also get the MD5 file hash using the ''%%md5sum%%'' command, |
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<code>md5sum nethserver-6.7-x86_64.iso | <code>md5sum nethserver-7.9.2009-x86_64.iso |
695ac8fe87b21501cc438abc411d8f02 nethserver-6.7-x86_64.iso</code> | 6a32d2738aafdcf4e124c2822e5c668d nethserver-7.9.2009-x86_64.iso</code> |
and if you have downloaded the original MD5 file hash to the same folder as NethServer's ISO image, you can use ''%%md5sum%%'' command to check its integrity: | and if you have downloaded the original MD5 file hash to the same folder as NethServer's ISO image, you can use ''%%md5sum%%'' command to check its integrity: |
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Example: | Example: |
<code>md5sum --check nethserver-6.7-x86_64.iso.md5 | <code>md5sum --check nethserver-7.9.2009-x86_64.iso.md5 |
nethserver-6.7-x86_64.iso: OK</code> | nethserver-7.9.2009-x86_64.iso: OK</code> |
**Getting and comparing SHA1 checksums**\\ In both, GNU/Linux and Mac OS X Operating Systems, you can use ''%%openssl%%'' or ''%%shasum%%'' command to get the SHA1 hash of a file: | **Getting and comparing SHA1 checksums**\\ In both, GNU/Linux and Mac OS X Operating Systems, you can use ''%%openssl%%'' or ''%%shasum%%'' command to get the SHA1 hash of a file: |
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''%%openssl%%'' example: | ''%%openssl%%'' example: |
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<code>openssl sha1 nethserver-6.7-x86_64.iso | <code>openssl sha1 nethserver-7.9.2009-x86_64.iso |
SHA1(nethserver-6.7-x86_64.iso)= 1e4d822b92d391c2f5d93f33af8a034cdcf2cf7e</code> | SHA1(nethserver-7.9.2009-x86_64.iso)= 9e3e67f13328163cfd383d1e0fcb7288eed282b8</code> |
''%%shasum%%'' example: | ''%%shasum%%'' example: |
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<code>shasum nethserver-6.7-x86_64.iso | <code>shasum nethserver-7.9.2009-x86_64.iso |
1e4d822b92d391c2f5d93f33af8a034cdcf2cf7e nethserver-6.7-x86_64.iso</code> | 9e3e67f13328163cfd383d1e0fcb7288eed282b8 nethserver-7.9.2009-x86_64.iso</code> |
If you have downloaded the original SHA1 file hash to the same folder as NethServer's ISO image, you can check its integrity with the ''%%shasum%%'' command: | If you have downloaded the original SHA1 file hash to the same folder as NethServer's ISO image, you can check its integrity with the ''%%shasum%%'' command: |
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Example: | Example: |
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<code>shasum --check nethserver-6.7-x86_64.iso.sha1 | <code>shasum --check nethserver-7.9.2009-x86_64.iso.sha1 |
nethserver-6.7-x86_64.iso: OK</code> | nethserver-7.9.2009-x86_64.iso: OK</code> |
On **GNU/Linux**, you can also use the ''%%sha1sum%%'' command in place of ''%%shasum%%''. | On **GNU/Linux**, you can also use the ''%%sha1sum%%'' command in place of ''%%shasum%%''. |
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Alternative programs might exist on each Operating System. | Alternative programs might exist on each Operating System. |
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{{tag>ht_installation userguides before_installation}} | {{tag>ht_installation userguide before_installation}} |