Hey Hey,

You are most definately not understanding the functionality of that software... You have basically already answered your own question though.... you require some sort of Proxy server if you're going to modify http traffic in real time.

Achilles (http://www.mavensecurity.com/achilles) is a very popular proxy used for this purpose in Windows environments (It can also be used along with wine under Linux.. however there are other choices in both environments)

As for the tools you mentioned..

Ethereal is a sniffer... It lets you see what's travelling across the wire, however you can't touch the data... Think of it as a Read-Only device.

NetCat is for creating connections or opening a port... so you could use this to talk to an HTTP server... but you'd be sending the requests to it manually..

> nc www.antionline.com 80
> GET / HTTP/1.0
> [CRLF]
> [CRLF]


Peace,
HT