You may see the term IPS for Intrusion Prevention Systems which takes things one step further, having the IDS adjust the firewall when it discovers something.
Smart people disagree on the use of IPSs as it, in effect, gives an attacker some control of your firewall.
If you installed Docker using the convenience script, you should upgrade Docker using your package manager directly.
To install the latest testing version, use test.instead.
(Just make sure you're getting a hub as many people use the terms hub and switch interchangeably.) If you want to monitor traffic on your internal network, you could configure port spanning on your switch.
Port spanning simply takes all of the traffic on one or more switch ports and duplicates it to a span port that has a monitoring device connected.
Continue to Linux postinstall to allow non-privileged users to run Docker commands and for other optional configuration steps.
For Raspbian, you can optionally install Docker Compose for Raspbian.