What's the easiest way to sniff TCP traffic data on Linux?

Problem

I want a simple way to show all the TCP data (not the TCP headers or anything else) going over any interface on my Linux box. For instance, I want a magical command that if I do: then if there was a server listening on port 1234 on my machine, and someone did: Then the magical command would just print out: I've tried "tcpdump", "ethereal", "tethereal", "tshark", and others, but it isn't obvious how you get them to: not show IP addresses or other metadata only show the "data" being sent, not individual packets and their headers print the data as-is, not in hex, and not with packet-offset markers sniff all network traffic (whether it's on eth0 or eth1 or lo, etc...) Yes, you could probably string together a piped set of unix commands to do this, but that isn't very easy to remember for next time :) If you have a simple example of an exact command-line that does this, that's what I'd like.