nice try. but in practice if you try to connect to 0.0.0.0 you'll
get
an error, which is what we want to happen.
That depends on your OS:
mine$ uname -a
SunOS mine 5.9 Generic_117171-12 sun4u sparc SUNW,Ultra-2
mine$ telnet 0.0.0.0 25
Trying 0.0.0.0...
Connected to 0.0.0.0.
Escape character is '^]'.
220 mine ESMTP Sendmail 8.13.1/8.13.1; Mon, 28 Feb 2005 05:48:09
+0100 (MET)
windlord:~> uname -a
Linux windlord 2.4.26 #1 Tue Apr 20 16:17:15 PDT 2004 i686 GNU/Linux
windlord:~> telnet 0.0.0.0 smtp
Trying 0.0.0.0...
Connected to 0.0.0.0 (0.0.0.0).
Escape character is '^]'.
220 windlord.stanford.edu ESMTP
quit
221 windlord.stanford.edu
Connection closed by foreign host.
sigh. I stand corrected. (I thought I had tried these cases, but must
have tried something else.)