Lock the NGINX User Account

>Draft CIS Benchmark 1.1.3 (**Level 2 Control**)

## Description
The user account under which NGINX runs should not have a valid password, but should be locked.

## Rationale
As a defense-in-depth measure the NGINX user account should be locked to prevent logins, and to prevent a user from su-ing to `nginx `using the password. In general there shouldn't be a need for anyone to have to `su `as `nginx`, and when there is a need, then `sudo `should be used instead, which would not require the `nginx `account password.

## Remediation
Use the `passwd `command to lock the `nginx `account: ``` # passwd -l nginx ```

## Audit
Ensure the `nginx `account is locked using the following: ``` # passwd -S nginx ``` The results will be similar to the following: ``` nginx LK 2016-06-23 0 99999 7 -1 (Password locked.) ``` or ``` nginx L 06/23/2016 -1 -1 -1 -1 ```