I still have a Slackware install that runs some really old stuff I have. I remember working at AN ISP in the 90s and slack was are secure distro. All the important stuff (authentication, configs, etc.) were stored and served from our 'slack pool'.

Funny part is now I do a very basic Slackware install that setup pkgsrc (https://pkgsrc.org) on it so I can really experience the best and worst of times!