This was one the most difficult machine I’ve faced until now. Not because it’s really hard, but because it’s so full of rabbit holes that makes you crazy!!!
Anyway, I’ve got user.txt (after a couple of days) and root.txt, that need a couple of minutes if you know what is going on, but a while if you want to learn something new 
Thanks to everyone that helped me, expecially to @p0wn3y for the first part and @m4xp0wer and @absf1 for the root part.
A couple of hints:
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initial foothold: enumerate every port you’ve, every information you get can be useful for the next steps, and I mean every!
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user: when you get the right page (that gives you “information” about what you should do) try to understand well what is going on
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root: enumerate well, something will come up (follow the g0tmilk guide). As other have said, then follow the snake. Try to understand well how it works and you’ll be fine
PM if you need more help!