sniffing plaintext protocols

["itsec.info" <itsec.info () gmail com>]

Hi

The background for the following questions is purely due to feasibiltiy 
reasons for pentests and there is no interest in hacking.

I have read many articles about sniffing, spoofing and relaying.
So far I learned that it is possible to connect a host, hostA, between two 
existing hosts, host1 and host2, in order to sniff e.g. plaintext protcols 
like telnet, pop3, and ftp.

1)
Is this only in a local network possible or also in the Internet?

2)
I would lik to test such a scenario in my private local network in order to 
prove myself and my team, that this is really possible.

Can anybody provide me a kind of how-to for this scenario.
I run different linux machines on my local network and on hostA I have various 
tools installed like dsniff, hunt, fakerout, P.A.T.H, wireshark, etc.

--
Any help is very much appreciated.
Regards,
Mike

------------------------------------------------------------------------------
This List Sponsored by: Cenzic

Concerned about Web Application Security? 
Why not go with the #1 solution - Cenzic, the only one to win the Analyst's 
Choice Award from eWeek. As attacks through web applications continue to rise, 
you need to proactively protect your applications from hackers. Cenzic has the 
most comprehensive solutions to meet your application security penetration 
testing and vulnerability management needs. You have an option to go with a 
managed service (Cenzic ClickToSecure) or an enterprise software 
(Cenzic Hailstorm). Download FREE whitepaper on how a managed service can 
help you: http://www.cenzic.com/news_events/wpappsec.php 
And, now for a limited time we can do a FREE audit for you to confirm your 
results from other product. Contact us at request () cenzic com for details.
------------------------------------------------------------------------------