Packets Route and tcpdump

[TheNightMare]

Hi
I have number of computers in my network and I just
want to check if the packets passes ( is forwarded ) through the computers or not,
I tried Tcpdump but it did not work as I want,
for example if I send packets from A to C through B, ( A > B > C )
D will capture the packets even though it did not passed through it.
how can I tell if the packet is passed through the computer or it just heared it ?

Thanks in advance

[Lazydog]

man traceroute