Linux: Add first networking challenge: Firewall management

[ryapric]

Part of #8, but I also got carried away.

This PR:

• Adds a basic firewall-management challenge using ufw. The expectations are outlined in challenge_5.md, where I would want them to use nmap to hit the DB server to check open ports, then fix the broken one. Though admittedly, they won't have to if they run e.g. ufw status. Note that I did also make sure port 8000 is open in main.tf as well.

• Renames occurrences of step to challenge to better describe what they actually are.

• Replaces printf calls that were pseudo-logs with ezlog

• This also tightens up test.bats to include tests against pre-solved states.

• Adds a simple GitHub Actions workflow to run linux/scripts/ci.sh

[ryapric]

@JDeBo this is ready for first-pass review now, just as a part of #8 and not the whole set of ideas yet.

[ryapric]

@JDeBo ok I think we're in a good spot to merge this once we scrutinize challenge_5.md

[JDeBo]

Other than those small fixes, lgtm, I've got it merged into my branch so pls no huge rebases lol

[JDeBo]

Other than those small fixes, lgtm, I've got it merged into my branch so pls no huge rebases lol

You ever see this issue with the ezlog install in Vagrant?

    db: Cloning into '/usr/local/share/ezlog'...
    db: fatal: unable to access 'https://github.com/opensourcecorp/ezlog.git/': server certificate verification failed. CAfile: none CRLfile: none
The SSH command responded with a non-zero exit status. Vagrant
assumes that this means the command failed. The output for this command
should be in the log above. Please read the output to determine what
went wrong.

[ryapric]

Which small fixes do you mean?

Also no, but that looks like a proxy error -- especially if you're running on your work laptop, it might be that.

[JDeBo]

Which small fixes do you mean?

Also no, but that looks like a proxy error -- especially if you're running on your work laptop, it might be that.

#9 (comment)

A couple small formatting things above like this

[JDeBo]

Which small fixes do you mean?
Also no, but that looks like a proxy error -- especially if you're running on your work laptop, it might be that.

#9 (comment)

A couple small formatting things above like this

Okay... so turns out I just don't understand how PR comments work in Github. Apparently I hadn't submitted them, hopefully you're able to view them now.

[ryapric]

Which small fixes do you mean?
Also no, but that looks like a proxy error -- especially if you're running on your work laptop, it might be that.

#9 (comment)
A couple small formatting things above like this

Okay... so turns out I just don't understand how PR comments work in Github. Apparently I hadn't submitted them, hopefully you're able to view them now.

Yeah I was very confused but I see them now 😂 thank you!

[JDeBo]

lgtm