The way the network in my school works is that everyone has his own account with that he/she can login into the system and their userspace and stuff. Is required to be able to download stuff.
However, there is always a stationary account with that you can login to only that pc, you can still use the internet but downloading has been disabled somehow.
Also every time the pc gets shut off and turned on again it runs a program called "MySHN" that resets whatever you have done outside your userspace on that pc to a pre-defined image.
so basically what i did was go into the stationary account, which has local admins permissions, and used that to access the user management to reset the password of the local "administrator" of that pc (which somehow appearently also overrides the perms of our school's global administrator who should be the only person who has admin perms outside of that stationary account but hey i wont complain)
When I was done there, went into my own account, went to the windows Firewall, clicked on disable and when it prompted to enter the username and password of an administrator account i entered the ones of the local one that i have changed before, which surprsingly worked.
Well at that point i had free play, or so i thought.
I still had to find a way to bypass the fact that the system administrator blocked most network gateway ports, especially those used by 90% of online games to connect to gameservers.
Which means that a regular minecraft lan server does not work because it goes through a port that is blocked.
So I downloaded the regular minecraft server software jar, ran it and used the local ipv4 of that pc as an ip address (the port 25565 used by that server appearently works)
turns out only the host has to actually disable his firewall, and everyone else in the entire school can theoretically join the game.
bam done. Also while i was at it i also found a nice proxy tunnel website that lets me bypass that webfilter.
So yeah, thats about what me and my friends do during recess