When I was student (1990-1993), there was no firewall. My girlfriend was in another school in Paris (I was in Brest). I used xhtalk to see if she was logged in

When I was student (1990-1993), there was no firewall. My girlfriend was in another school in Paris (I was in Brest). I used xhtalk to see if she was logged in and chat with her. I could perform a rlogin on any computer of the other school. When I was at her school, I could run programs (like xdvi) remotely by exporting the DISPLAY. The file /etc/passwd contained the hashed passwords and with a simple dictionnary, you could find passwords in minutes. At that time, the main tools were newsgroups (for information sharing) and xarchie (to find ftp mirrors of free programs). I have used also gopher to find CERT list of vulnerabilities. I have found how to exploit one of them. I have notified the administrator. A couple of weeks latter, this was not fixed, I have setup a permanent root backdoor that was still working one year after my departure. There were "site" you could connect using telnet. For example igs (https://en.wikipedia.org/wiki/Internet_Go_server https://en.wikipedia.org/wiki/Internet_Go_server). I remember also a site in australia that was used to find email adress of people from their name and their approximative location. Using the ping delay, you could know if your communication was going throw a satelite or not.