Recently I came across a discussion where a commentator pointed out that OVH uses modified Ubuntu images in their cloud service. That means that when I choose to deploy an Ubuntu image on OVH cloud I won't have an original Ubuntu.
I am currently client of Digital Ocean (DO) where I have Ubuntu deployed. I have noticed in the sources.list file some DO repositories (preceded by a warning comment
ENTIRELY UNSUPPORTED by the Ubuntu team) . I understand that they have mirrors to speed updates and limit their bandwidth use, but I am concerned about the originality of the images I am using, thus my question: How I make sure the packages I am using come really from Ubuntu's packages? Is modifying the sources.list files sufficient to have the right packages?
Note: DO has had in the past a security problem, due (in my understanding) to the cloud images they use.