In early Ethernet networks, vampire taps were used to connect devices to a single coaxial cable.<p>You could add a new device in between physically - without disrupting existing connections.<p>Here's an actual video of a connector bring made:<p><a href="https://youtu.be/ehCwqMkAxq0" rel="nofollow noreferrer">https://youtu.be/ehCwqMkAxq0</a>