Question : how to monitor traffic on linux interfaces

Is there a command to check traffic (bandwidth) coming in and going out on Ethernet interfaces?

Answer : how to monitor traffic on linux interfaces

you would be able to see by using any of bellow tools

tcptrack  :http://www.rhythm.cx/~steve/devel/tcptrack/release/1.3.0/docs/tcptrack.1.html
ngrep :     http://www.linux.com/archive/feature/46268
ntop :
mrtg:
vnstat: http://humdi.net/vnstat/