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I'm monitoring my server's port assignment and found a strange thing...

I used IBM Websphere Liberty and found that one port has 2 status(listening and established...), that's odd...

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10318 is my listening port for this liberty server...But it has 2 status...

So could anyone can explain to me about this?

I thought that one port can only has one status at one time...

Thanks so much!

Jiddu.K
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    This is routine for any TCP listening port that ever gets used. When it's idle, there's a single listening socket in netstat. For each client connected to that port, there's also an established socket. – covener Dec 15 '17 at 01:21
  • @covener Thanks for your answer! I'm just not familiar with TCP/IP protocol... :-) – Jiddu.K Jan 03 '18 at 02:03

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Notice the connection number is different between the listener and established sockets. As long as the combination of the 4 numbers of local port and socket and foreign port and socket is unique, you can establish multiple sockets, ie in your netstat output, 9.20.4.125..3305 can't establish another connection to 9.20.4.125..10318.

F Rowe
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