How to monitor who “talks” with my server?

How to monitor who “talks” with my server?:

Hello everybody. I’ve configured a server mostly to download torrents. I used ubuntu server and I use to connect by using ssh.

Is there a way to control if someone is trying to connect to it? How could I make it a bit more secure?

The question is because I’m on a university college’s network and there are free wifi that could allow everybody who walks near my building to connect to the network.

submitted by /u/segmentationfrault
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