You can’t just start hacking immediately after you exit the Vault though. So what exactly do you do then? Yup, you hack the terminal.

Unfortunately, almost all such terminals tend to have passwords, and aside from a handful of them, you won’t be able to find the password. The only way to open such doors is by using a terminal. Hacking is an extremely important part of Fallout 4, as many essential areas and unique items are locked away behind a secured door. This guide will thoroughly cover how Hacking and Lockpicking in Fallout 4 works. Thankfully, you have the necessary tools and the required skill-set to perform both.

Источник: Fallout 4 Hacking and Lockpicking Tips