I have a virtualized CentOS machine with a software that is listening on port 8080. I have turned off SELinux and flushed all iptables (so now there are no rules set). I have checked with
netstat -nap | grep 8080 that the port is really open and it is. The IP adress is 192.168.1.3.
From my other machine, I would like to connect to that port with a program but it fails. When running
nmap -p 8080 192.168.1.3 it says the port is closed!
When I check with Wireshark I can see that the connecting computer is sending the SYN packet but the responding computer (with IP 192.168.1.3) responds with a SYN/RESET and interrupts the connection and do not respond with a SYN/ACK and thereby continues the transmitting. The sequence number is correct, the sending computer sends 0 and the receiving one receives 1.
The strange thing is that other ports can be detected as open by Nmap from the client machine, but not 8080.
What can be wrong?
Ok, i don´t know what to believe on now. This is what I have discovered:
The porgram that is listening on 8080 on the "server machine" (let´s call it so) is a custom-made webservice built in Java (using third party libraries as EclipseLink etc). When doing
nmap localhost on the "server machine", it can find the port open. When doing
nmap 192.168.1.3 from the "client machine" it finds the port closed (as described above).
And the new discover: i just made a simple java app that just uses the ServerSocket class to listen on 8080 and THEN the port is discoverable from the "client machine". So, is it something with the webservice app? Why is the port discoverable from the "server machine" (when scanning itself, localhost) but not from the "client machine" when running the webservice? And why is port 8080 discoverable from BOTH machines when running the simple java app that listens on 8080?
netstat -ntpl tcp 0 0 ::ffff:127.0.0.1:8080 :::* LISTEN 3481/java
Stupid me! Now I see,
::ffff:127.0.0.1:8080 means that the program is only reachable from localhost! :-D
Where do I change so it listens from all?