Port 5355 opened on the internet

I have an Ubuntu box that is connected to the internet and provides ICS.

If I list the open ports by running:

netstat -tulnap | grep LISTEN

it shows me:

tcp 0 0 127.0.0.1:445 0.0.0.0:* LISTEN 1419/smbd
tcp 0 0 192.168.0.2:445 0.0.0.0:* LISTEN 1419/smbd
tcp 0 0 127.0.0.1:139 0.0.0.0:* LISTEN 1419/smbd
tcp 0 0 192.168.0.2:139 0.0.0.0:* LISTEN 1419/smbd
tcp 0 0 0.0.0.0:5355 0.0.0.0:* LISTEN 1056/systemd-resolv
tcp 0 0 192.168.0.2:53 0.0.0.0:* LISTEN 1130/dnsmasq
tcp 0 0 192.168.0.2:22 0.0.0.0:* LISTEN 1189/sshd
tcp6 0 0 :::5355 :::* LISTEN 1056/systemd-resolv

where, clearly, port 5355 is open on the internet.

Does this open port pose any threat?

2 Answers

This is the systemd-resolved that provides network name resolution to local applications via a D-Bus interface. See here

Although I don't quiet get why it is running on a public address. This does not seem to be the default. One could firewall the port or re-configure the service.

No, it is not a threat.

It is link-local Multicast name resolution provided by systemd. Details are here :