How to connect java server to external network interface in Linux?

Question

Java

I start a simple echo server on linux centos:

ServerSocket server = new ServerSocket(portNumber);

or

ServerSocket server = new ServerSocket(portNumber, 10, InetAddress.getLocalHost());

In the console I get, for example:
SERVER :: created Se>rverSocket[addr=vm531350/_serverip_,localport=8080]

In any case, netstat -anp gives:
tcp 0 0 :::8080 :::* LISTEN 27285/java
or
tcp 0 0 ::ffff:_serverip_:8080 :::* LISTEN 27285/java

The server pings normally, everything comes through telnet from another computer, I checked it using tcpdump. But the connection, namely, to the java program does not occur.
That is, this socket is listening locally, do I understand correctly? How to switch to external interface?

hosts file:
_serverip_ vm531350 vm531350 localhost
::1 vm531350 vm531350 ip6-localhost
_serverip_ vm531350
_serverip6_ vm531350

Debate on finding the problem here: https://toster.ru/q/227455

Answer 1

Instead of:
use:
Looks like getLocalHost() still doesn't resolve correctly (as already discussed in the parallel question).
PS Here is another useful info on the topic.