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Commonly open port ranges

Some applications such as MOSH or KDE Connect are just so practical, but they open so many ports in firewall and who is to guarantee lazy sysadmin won’t abuse those for something else without even thinking about backdoors?

The following list is based on my other notes and /usr/lib/firewalld/services/

Services doing it right?

<?xml version="1.0" encoding="utf-8" ?>
<service>
  <short>Multicast DNS (mDNS)</short>
  <description>mDNS provides the ability to use DNS programming interfaces, packet formats and operating semantics in a small network without a conventional DNS server. If you plan to use Avahi, do not disable this option.</description>
  <port
    protocol="udp"
    port="5353" />
  <destination
    ipv4="224.0.0.251"
    ipv6="ff02::fb" />
</service>

Note the destinations! Maybe I should copy that for some of my services like NTP.

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