I want to install `netstat` on my Docker container.

I looked here <https://askubuntu.com/questions/813579/netstat-or-alternative-in-docker-ubuntu-server-16-04-container> so I'm trying to install it like this:

```
apt-get install net-tools

```

However, I'm getting:

```
Reading package lists... Done
Building dependency tree
Reading state information... Done
E: Unable to locate package net-tools

```

So how can I install `netstat`?