Why does attempting to remove certain kernels, reinstall them?

Saeven

2/26/23, 2:12 PM

I've never run across this issue, but was hopeful to get a bit of guidance before I dig in.

This is occurring on Ubuntu 18.04.6 LTS.

$ uname -r
4.15.0-161-generic

$ dpkg --list | grep linux-image
ii  linux-image-4.15.0-153-generic         4.15.0-153.160                                                     amd64        Signed kernel image generic
ii  linux-image-4.15.0-156-generic         4.15.0-156.163                                                     amd64        Signed kernel image generic
ii  linux-image-4.15.0-161-generic         4.15.0-161.169                                                     amd64        Signed kernel image generic
ii  linux-image-generic                    4.15.0.161.150                                                     amd64        Generic Linux kernel image
ii  linux-image-virtual                    4.15.0.161.150                                                     amd64        Virtual Linux kernel image

AWS Inspector is asking me to nuke the old kernels, so I set out to remove 153/156, to leave 161. So I issue:

$ sudo apt-get purge linux-image-4.15.0-153-generic
Reading package lists... Done
Building dependency tree       
Reading state information... Done
The following additional packages will be installed:
  linux-image-unsigned-4.15.0-153-generic
Suggested packages:
  fdutils linux-doc-4.15.0 | linux-source-4.15.0 linux-tools
The following packages will be REMOVED:
  linux-image-4.15.0-153-generic* linux-modules-extra-4.15.0-153-generic*
The following NEW packages will be installed:
  linux-image-unsigned-4.15.0-153-generic
0 upgraded, 1 newly installed, 2 to remove and 0 not upgraded.
Need to get 8,108 kB of archives.
After this operation, 181 MB disk space will be freed.
Do you want to continue? [Y/n]

Why is it, that attempting to remove it, prompts apt to reinstall an unsigned version?

Thanks for your guidance!

0 + 0

apt

dpkg

kernel