Trace port usage by client-server service
 

Hi all, I have a java client that invoke a remote smtps service on opened port 465. I opened this port on my firewall net too, but service goes in timeout error because it can't connect to 25 smtp port. So I opened this port too and now all works fine. Since service manager said me that open 465 port was enough for service usage, sounds strange the port 25 utilization by service; so now I'd like to exactly track packets exchanging between client and server on 25 and 465 doors. How can I do? Thank you.

install wireshark and capture the traffic. Or tcpdump which is probably already installed if this is a linux client.

Thanks, I resolved by tcpdump