Ask HN: How do you secure your Linux/BSD computer?

Like the similar threads about Mac[1] and Windows[2], how do you secure your Linux or BSD based system?<p>[1]: https:&#x2F;&#x2F;news.ycombinator.com&#x2F;item?id=19681270 [2]: https:&#x2F;&#x2F;news.ycombinator.com&#x2F;item?id=19698620