Why are ports 53 and 5353 opened?

My YunoHost server

Hardware: computer
YunoHost version: 4.0.8
I have access to my server : Through SSH, through the webadmin
Are you in a special context or did you perform some particular tweaking on your YunoHost instance ? : yes
If yes, please explain: yunohost is running in a VM

Description of my issue

I noticed that in my yunohost the ports 53 and 5353 are open. Searching online, I found that those ports are usually used for DNS and Multicast DNS respectively.
I didn’t see any info about those ports in yunohost doc, they are not present in ports.yunohost.org or in ynh diagnosis.
So I wonder what are those ports intended for, and if I should leave them open, or close them.
(I don’t think I opened them manually, could be an app that I installed in the past that did it, don’t know.)

Indeed the diagnosis doesn’t mention it … I thought it would be, but in fact that’s because these ports are not meant to be publicly accessible

Port 53 is related to dnsmasq … I think in the general case it’s not really useful to have it opened on the firewall but in some cases, people may want to use their local yunohost/dnsmasq as a dns server, so that’s useful for this … (though i guess ideally it should only be opened if you do want to do this)

Port 5353 is for avahi-daemon / bonjour protocol, related to the ability to reach your server using “yunohost.local” which is not too much advertised but there are some investigations ongoing about this

1 Like

Ok, I understand.
Thank you @Aleks for the infos :slight_smile:

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