I want to use Exim4 as an MTA for my server, but basically only to send emails. For security issues, I would like to restrict incoming connections to localhost only (I think). So there is this option in the exim4 configuration where you can specify:
IP-addresses to listen on for incomming SMTP connections:
If I put localhost there, I can perfectly well send emails via mutt and mail, but other services on my machine cannot connect to the exim daemon to send emails, especially because there is no binding to the port tcp/25 if I specify localhost in the field above.
Of course if I leave the field blank, everything works fine, but I don't want to listen for tcp/25 for anybody else than my own machine... Here is my log when all connections are accepted, for local services like ossec:
2013-10-08 12:26:13 1VTcv7-XXXXX-XX <= firstname.lastname@example.org H=localhost (notify.ossec.net) [127.0.0.1] P=smtp S=979