Development Linux Ubuntu

Trying to open port on Ubuntu 18.04 Server – I’m missing something

I’m trying to open port 30080 on an Ubuntu 18.04 Server vm and seeing some confusing results.

I did an iptables -L -n and this line was in the output:

ACCEPT     tcp  --   tcp dpt:30080

Also, ufw shows the port as open:

sudo ufw status
Status: active

To               Action      From
--               ------      ----
30080            ALLOW       Anywhere
30080/tcp        ALLOW       Anywhere

Netstat also shows the port in “Listening” mode:

netstat -talpn | grep 30080
tcp6    0    0 :::30080      :::*           LISTEN      -

So I’m not sure why nmap still shows the port as filtered:

nmap -Pn localhost -p 30080 
30080/tcp filtered unknown

And if I try from a remote machine, nmap shows as closed:

30080/tcp closed unknown

Not sure where to go from here.

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