How to see dumps of wholе HTTP packets

Try tcpflow:

tcpflow -p -c -i eth0 port 80 | grep -oE '(GET|POST|HEAD) .* HTTP/1.[01]|Host: .*'

Output is like this:

GET /search?q=stack+exchange&btnI=I%27m+Feeling+Lucky HTTP/1.1
Host: www.google.com

You can obviously add additional HTTP methods to the grep statement, and use sed to combine the two lines into a full URL.

Simple core command line tools like nc, socat seem not to be able to handle the specific HTTP stuff going on (chunks, transfer encodings, etc.). As a result this may produce unexpected behaviour compared to talking to a real web server. So, my first thought is to share the quickest way I know of setting up a tiny web server and making it just do what you want: dump all output.

The shortest I could come up with using Python Tornado:

#!/usr/bin/env python

import tornado.ioloop
import tornado.web
import pprint

class MyDumpHandler(tornado.web.RequestHandler):
    def post(self):
        pprint.pprint(self.request)
        pprint.pprint(self.request.body)

if __name__ == "__main__":
    tornado.web.Application([(r"/.*", MyDumpHandler),]).listen(8080)
    tornado.ioloop.IOLoop.instance().start()

Replace the pprint line to output only the specific fields you need, for example self.request.body or self.request.headers. In the example above it listens on port 8080, on all interfaces.

Alternatives to this are plenty. web.py, Bottle, etc.

^{(I'm quite Python oriented, sorry)}

If you don't like its way of outputting, just run it anyway and try tcpdump like this:

tcpdump -i lo 'tcp[32:4] = 0x484f535420'

to see a real raw dump of all HTTP-POST requests. Alternatively, just run Wireshark.