How can I monitor the amount of data sent/received to/from a specific host? I've found som tools to monitor tx/rx and show the overall data usage and live graphs etc.
But what I need is a tool to monitor how much data has been transferred
between my machine and a specific host.
Is there any tool where I can specify an IP/hostname for yosemite?

And just to clarify the needs:
required is


Dumping/graphing the incoming/outgoing network data  
Limiting the output to a specific host
Easily readable output (regarding the units - Mb/GB etc.)
"Counter" can be reset


Does anything like this exist?
IStat menu gives you this data.
The only thing missing is counter I think it only gives you total since boot for a network interface.