Ethernet Splitter or Switch?

[manjuice]

To receive my internet I have an ethernet outlet shown below:

Sometimes my friends come round to my flat with their laptop and would also like internet. Is there such thing as a ethernet splitter for this or do I need an ethernet switch?

(the left outlet is for telephone and not internet)

Thanks

 

[manjuice]

You need to be very careful as a switch might not be appropriate. What type of connection is it and who is it supplied by?

I'm not sure, all I know is that I am using a cat5e cable to my laptop.