i am newbie guys so plz bear.... i have a tcp packet captured in ethereal... i know the flow of the packets and also the application which created the packets and also the what data is send..... my question is HOW do u read this captured tcp packet (the data field).
Thats up to the higher layers (Application). If it's say a web browser (HTTP), then ethereal (or wireshark) will decode it. right click on the first packet and click "Fllow TCP stream". It will show you the decoded HTTP conversation.
If it's an other unknown application, it might not be decoded.
As far as i've seen in this app. it will decode the binairy towards ascii for readability (not sure if that's a correct english word.. but who gives a crap ).
You can press the [+] in the data field to expand the package and see whats inside. Just try to send a MIME package (mail) and capture it with your Ethereal, you will see you can read exactly what's in the mail, to who it is send and from whom it is.
There's also a hex viewer as far as I know but you can neglect that one for this purpose.