I was playing minecraft today while using meteor client and I realized that you can use other accounts. I tried the admins account and what do you guess, it worked. I can use admin commands but not until I login to the account. Is there a way that I can figure out his password?
I'm guessing you were playing on a cracked server, meaning that you don't have to own the game in order to sign in. That's why you were able to sign in with any username, usually, it wouldn't be that easy.