How to checking physical ethernet connection?

Hello, All !

Please, explain me, how to check physical ethernet connection (jack plug or unplug), if am using standard ethernet library?

For my project i use Arduino Ethernet board. I need to check only stuck into RJ-45 plug in the card or not. In the library I could not find a similar example.

thank you.
Denis.

Thanks for the detailed answers! I solved the problem.

Thank you
Denis.

I need to check only stuck into RJ-45 plug in the card or not

A mechanical limit switch attached at the rj45 jack that is actuated when the rj45 plug is inserted might be an option.