Correctly received bytes?

I have been puzzled over how to find out between correctly received bytes and total received bytes in the UNIX system.

So far, I guess that the information provided by the ifconfig or netstat command provides me with the total transmitted/received packets and bytes over each of my connections.

On the other hand, where can i find out how many bytes that I have actually correctly received? I know the number of packets that have errors but I don't know how many bytes were in each packet, so that I wouldn't know how many bytes were lost.

Is there another way or another system command for this?

Thanks

What Unix system?
If it's a Linux system, IPTraf is pretty cool, and may give you what you want:
http://cebu.mozcom.com/riker/iptraf/

I'm sure such utilities exist for other flavors...

Actually, I run on a non-Linux system. But.. the link was good though. Thanks.