Ethernet header question

Hi guys! I am successfully using my Arduino as an ethernet server with the W5100.
What I’m curious about is why exactly the read data coming from the buffer only includes the bytes of data the client intended to actually send.
(See attached for picture, in all of that transmitted data, the controller only acknowledged my input, “F”).

Not that I’m complaining, as this makes life easier. I was just wondering if you guys knew what that header information includes/is used for.

Thanks-

The W100 is a "smart" controller that does all the processing up through tcp FOR you, and provides APIs similar to unix "sockets."
Under normal circumstances on sockets, you send data (bytes like your 'F') and receive data, with all the packetization and stuff done invisibly.

westfw is on the money, notice your IP addresses n ports mixed in there:

c0 a8 01 8c == 192.168.1.140
c0 a8 01 77 == 192.168.1.119
f2 30 == 62000
00 17 == 23

Very cool, thanks for the information guys!