If you want to tap Ethernet traffic i think you can just wire the lines to your port with short wires, but you need two ports to monitor the two directions, and convince the ports to believe they’re linked (in software or hardware) if necessary

Most smart switches let you span ports

good luck finding a gigabit “Hub”

Hubs are good if you want to sniff traffic passing through there. Switches will direct the traffic (except broadcast) to the right port. That hub sends everything. Keep it, if you have any interest in traffic sniffing.

As cheap as used switches are that support port mirroring, I don’t see much sense in a hub these days. At least with a switch and port mirroring, you can avoid collision nonsense that a hub will have. I’m all for keeping old hardware but hubs have been all but replaced by switches in all cases. Outside of ghetto traffic sniffing, I can’t think of a single other reason to keep one.

or avoid the collision nonsense and sniff using a switch that supports port mirroring

As cheap as used switches are that support port mirroring, I don’t see much sense in a hub these days. At least with a switch and port mirroring, you can avoid collision nonsense that a hub will have. I’m all for keeping old hardware but hubs have been all but replaced by switches in all cases. Outside of ghetto traffic sniffing, I can’t think of a single other reason to keep one.

Source: https://www.facebook.com/share/p/EZWD23nFK55LDCjB/

HUBs are useful also if you need to test that your embedded device works OK in all Ethernet modes (those half duplex 10M and 100M modes).