Comment 1 for bug 1650489

Thank you for filing a bug. There were several observations made so I'll mention a few things:

- ufw app list will only show apps that have registered with ufw. On your system, that is cups and samba
- surfing/etc work because ufw uses connection tracking and outgoing traffic is allowed by default. This means that if your system initiates a connection to the outside world, the response is allowed
- there are already rules for avahi (bonjour) to make discovery work, but connections to the discovered services would need rules allowing the connection
- you mentioned this is with a scanner. You almost certainly need to add nf_conntrack_sane to IPT_MODULES in /etc/default/ufw