Re: Strange behavior

[Fabio Busatto <fabio.busatto@sikurezza.org>]

On Fri, Feb 23, 2007 at 02:45:26PM +0100, Steffen Bisgaard wrote:
> Both domains resolve to the same ip address inside the LAN.
> It seems as if qmail, or tcpserver, is listening on port 25 but only on one 
> domain - is this possible?

This is a nonsense.
Programs bind ports on ip addresses, not on hostnames.
So, if you start a program with a hostname, it resolves and then uses
the associated ip address.
Telnet clients do the same, they first resolve the hostname into an
ip address and then connect to it.

All domain-related stuff could only be done at application layer, but
the tcp connection cannot be blocked (there is no way for the server
to know which is the hostname typed in the client looking only at the
layers from transport to link).

So, if you resolve both hostnames in the same ip address, telnet will
connect to both, or none.

Bye
Fabio