covert_tcp lab incorrect

[Gawdzilla]

I noticed your lab with covert_tcp seems to have a problem. When I use the tcpdump -nvvX port 8888 -i lo command its only monitoring the Loopback interface. In which case, it would find nothing anyway.
So I then switched it to use my eth0 interface and when I reran the lab, it picked up each packet. So it doesn't seem to hide anything. Unless I'm missing something here!