etherent extension

Hi all,
i have tried looking for an adaptor which extends a current ethernet cable further. So and adaptor which plugs in to both cat 5 ends. For example if i umplug a cirrent cat 5 cable form a device and its not long enough i need an adaptor which will connect that end to another cat 5 cable so it will reach the device i want to plug it into without unplugging the original cat 5 cable form the main port. If anyone can find one on the net for me then i will be most grateful as i cant seem to find one. I hope u can make sense of what i have just written.
Thanks

 

It's called a hub.

This link directs you to a Newegg.com product page for a device that is suitable.