We have an internal discussion about whether it is possible to block the 3 way hanshake TCP but allow the JDBC application protocol.
In other words we would like to block the test of the port with the command "telent address port" but we would like that the connections via JDBC continue to work.
is it possible to do this theoretically? Is it possibile to do it wiht paloalto firewall?
Please note: when I say blocking, I mean "connection refused" or "timeout". I do not intend to terminate the connection immediately.
if it is possible, could you explain to me how technically it happens?
The "telnet address port" command performs only the TCP handshake. So the packages do not contain any information about the application protocol that you want to use.
How can a firewall make assumptions and deny to initialize tcp protocol?
Remember the PAN needs to let traffic pass so it can identify the App-id. You might try and block the telnet application and see if that works. But blocking the tcp3way is not advised as it will not allow any traffic that is tcp.
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