Code for hacker's den doors

[Pesky]

SPOILERS for chapter 5.

In chapter 5, after leaving the water plant you walk right into a hacker's den. To leave it you need a code to open the doors. But this code is the other side of one fo the doors: you have to enter the code to see the thing that tells you the code. Or is there a way I missed ?

(I got the code from a walkthrough, so I'm out. I'm just curious about how I was meant to get it myself.)

[Scarchu [BG]]

At first, there is a code in the "log" file at the computer. THe second code is in the tablet and the third is at the wall outside. Inserting the first code allows you to turn off the alarm (if activated), unlock some of the doors and while crouching to reach the tablet.
P.S.: The tablet in the "living room".

[Pesky]

Ah, so getting to the tablet isn't from unlocking the doors, it's from turning off the sensors. Which automatically lets you through that door. I was sure I'd tried that and the door didn't open. Apparently not. Thanks.