Recently found on the server when caught not open, can also be got from the client the SYN type package,
When I was on the server computer (no operation service program) run caught tools, with a client to the server (target port 9999),
This time on the server to run wireshark caught tool, caught from the client the SYN packet, the diagram below:
Because the server is not running, the client request for a connection is established, there is no response, trying to give up after just a few times,
My question is, why hasn't the server on port 9999 or was received from the client the SYN packet?
I tried Windows and ubuntu computers have received the client's SYN types of TCP packets, however in the centos (cloud server) but can't catch on
Out of the bag, want to know how to also can be caught on centos this package?