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nping sends echo requests always to default port '9925' instead of user-defined port #1732
Started echo server on port 6005
From another echo-client machine, I issue TCP echo request on 6005
The reason for its failure is seen in tcpdump. It sends TCP sync to port '9929' instead of 6005.
I did the same to 'echo.nmap.org'. I observed that initially it sends few packets in '9929', then it switches to 6005.
I believe if someone wants to try echo-server and echo-client on only one port, it should be accomodated accordingly.
Nping's echo mode requires the client to specify how to connect to the echo server AND what probes to send that it will receive back from the echo server. The
As an example, perhaps I know that port 1234 works fine through my network boundary, but I want to know what is modifying traffic on port 80. I would set up an echo server internally, listening on port 1234:
Then I would connect my echo client over port 1234 to receive the echo responses, and send appropriate probes on port 80: