inetd + sysutil/socket VS net/tcpproxy

[Andrea Venturoli]

Hello.

I know this question will be vague and possibly a little OT, but I'm in 
search of some suggestion.



I've always used sysutil/socket to allow access to an internal server 
through a firewall, with an inetd.conf line like

> myport stream tcp4 nowait nobody /usr/local/bin/socket socket internalip myport

This has always worked (and still is in several cases), but now I found 
a custom program which would give a protocol error.

I tried replacing inetd+socket with net/tcpproxy and everything started 
working properly.





I might declare all is well and solved, but I'm very curious...

So I recorded the conversation with "tcpdump -s 65000 -w myfile port 
myport" and processed it with "tcpflow -o MyConv -r myfile"; I did this 
for both the "good" traffic (the working one, thanks to tcpproxy) and 
the "bad" traffic (the problematic one, with inetd+socket).
To my surprise they are identical!!!

So I'm left wondering why one works and the other doesn't.

Of course the size, timestamps, fragmentation of the data stream is not 
the same across the two packet sets, but I don't think that should matter.

Any suggestion?



  bye & Thanks
	av.