debugging remote websphere application from eclipse - websphere

Question

I've configured my server to run with the following flags:
Server--> Server Types --> WebSphere application servers --> Additional Properties --> Debugging Service:
JVM Debug Arguments= -Xdebug -Xnoagent -Xrunjdwp:transport=dt_socket,server=y,suspend=n,address=8888
JVM Port= 8888
I configured eclipse debug configuration with the server ip (verified that ip is reachable with the ping command) and port
To be sure i increased the debugger timeout as well .
I've got: Failed to connect to remote VM. Connection refused.
Connection refused: connect
so i did a port scan on the server with (nmap xxx.xxx.xxx.xxx -p 8888) and the port seems:
PORT STATE SERVICE
8888/tcp closed sun-answerbook
moreover looking at the section Server--> Server Types --> WebSphere application servers --> Communications-->Ports of WebSphere admin consolle
i don't see the port 8888 in the list.
what do i need to do?
open the port on the machine? (how?)
add the port in the list of the above mentioned section?
other?
###### EDITED ########
ADDITIONAL CHECKS
netstat -na | grep 8888 --->no listening port/doesn't show me nothing
----------------------------------------------------------------------------
[root#dmgr ~]# iptables -L
Chain INPUT (policy ACCEPT)
target prot opt source destination
Chain FORWARD (policy ACCEPT)
target prot opt source destination
Chain OUTPUT (policy ACCEPT)
target prot opt source destination
----------------------------------------------------------------------------
C:\Users\alex>nmap 192.168.115.235 -p 8888
Starting Nmap 7.60 ( https://nmap.org ) at 2018-02-23 10:58 ora solare Europa occidentale
Nmap scan report for xxxx.xxxxxxxxxxxx.com (192.168.115.235)
Host is up (0.0018s latency).
PORT STATE SERVICE
7777/tcp closed cbt
Nmap done: 1 IP address (1 host up) scanned in 4.59 seconds
so, no listening port on 8888, no iptables rules that deny the connection, how to investigate further?

Answer 1

You are almost there :-)
On the Debugging Service page where you set the port and arguments, there is a checkbox - Enable service at server startup - ensure that it is checked.
If not, check, and restart the server.
After that you should see the debugging port open. You can check it for example via netstat -an.
If the port is open and you still cannot connect then it is probably the firewall issue.
Here some more details about setting the debug - Starting the application server in debug mode