Sendmail and masq

[Eric Diamond]

Tuesday, April 27, 2004 9:00 AM David Benigni added:

> Accessible to the internet is a Fedora Cora 1 machine running 
> sendmail for a particular domain.  So, it has a MX record for 
> that domain.
> 
> Inside our firewall I have a Red Hat 7.3 machine that runs 
> sendmail locally that has access out of the firewall on port 25.
> 
> The 7.3 box just Whenever the 7.3 box sends mail out as root, 
> its return address is root at localhost.localdomain.  The 7.3 is 
> not in the same domain as the Fedora machine.  The mail 
> leaves the 7.3 box and gets to the Fedora machine.  At the 
> point where it hits the Fedora machine the return address is 
> rewritten as the domain of the Fedora machine.

This looks like normal behavior to me. anyID at localhost.localdomain is
not a valid, routable email address. It is only valid within the
confines of any single machine's internal mail system. It would be quite
normal and desirable for an internet aware MTA to change such an address
to one that is routable.

Eric Diamond
eDiamond Networking & Security
303-246-9555
eric at ediamond.net