Adding checks for CUPS

[sebastian-luna-valero]

Summary

This PR runs the following checks with ncat on VMs with public IPs:

# TCP check
ncat --nodns -z {ip} {port}

# UDP check
ncat --udp --nodns --idle-timeout 3s {ip} {port}

Note that checking accessible UPD ports is not as easy. [1]

Although these checks are not comprehensive, it may still be useful to confirm whether further checks are required.

[1] https://serverfault.com/questions/416205/testing-udp-port-connectivity

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Related issue :

[enolfc]

LGTM. Let's keep these optional for now