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I´ve got a question concerning updates with a Linux system. My system is Lubuntu 16.04.2 LTS, 64 bit.

I wanted to update my system recently. Among others there was a kernel update available (4.15.0-47-generic).

It so happened that out of some undefined reason the internet connection was a bit shaky and the download of the packages to be updated stopped. So quite a bit has already been downloaded and another bit was still to download.

A minute later I tried it again and the rest was downloaded alright. After the download was complete the installation process began and went through without any difficulties. It seems all packages (including the new kernel) were installed.

My question is:

Can I be sure that the update process went through alright under these circumstances?

Or in other words: Does Linux employ some mechanism that makes sure that the packages are completely and correctly downloaded before the actual installation process is triggered?

Tnx in advance. Rosika

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Yes Debian/Ubuntu (deb/apt) Packages and Package Management do contain a mechanism to ensure package security.

Apt-get package management uses public key cryptography to authenticate downloaded packages.

If you want to understand how, please refer to https://help.ubuntu.com/community/SecureApt which includes sections on

  1. Basic Concepts (Public Key crytography)
  2. How to Find a Key
  3. How to validate a Key
  4. The Web of Trust (verification of Keys)
  5. Validation of Release File and Packages
  6. Links for more information

An alternative source is upstream (Debian's) https://wiki.debian.org/SecureApt

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  • Tnx a lot for your answer and the links. That´s exactly what I wanted to know. Secure apt seems a fine strategy helping to ensure that installation proceeds well even after a temporary loss of internet connection. – Rosika Apr 3 '19 at 12:02

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