Setting up SMTP?

[James Mckenzie]

Hello,

I just installed Fedora, and installed Big Brother for network
monitoring.  This is my first time setting up linux, so sorry for a
newbie question.

I need the server to have SMTP running, so that users in our network
can send e-mails to the server, which will fire off a script to deal
with the e-mail.  For example an admin wants to acknowledge an alert,
he sends mail to bb at mylinuxbox.mydomain.com.

Initially SMTP wasn't running on my box.  So I just ran
/etc/rc3.d/S80sendmail start.  Okay now sendmail appears to be
running.  ps -aef | grep sendmail shows

root      1725     1  0 Oct25 ?        00:00:00 sendmail: accepting connections
smmsp     1734     1  0 Oct25 ?        00:00:00 sendmail: Queue
runner at 01:00:00 for /var/spool/clientmqueue

But if I telnet to port 25 on my system, I get connection refused. 
There is no firewall.

You did not install the default Fedora firewall, or did you disable it.

I assume I need to change something in my sendmail config?  I read the
Red Hat Linux Reference Guide and I couldn't really figure out what I
need to change.  I was a little concerned about this section:

dnl #
dnl # The following causes sendmail to only listen on the IPv4 loopback address
dnl # 127.0.0.1 and not on any other network devices. Remove the loopback
dnl # address restriction to accept email from the internet or intranet.
dnl #
DAEMON_OPTIONS(`Port=smtp,Addr=127.0.0.1, Name=MTA')dnl

It appears that you need to comment out that line so that inbound connections will work.  You might want to set it so that only your local network can connect.  This is good security practice.  It might be better to limit connections only from systems that you expect mail from, such as the maintance admin system.

Note - this system will be on the intranet.  Not internet accessible.  
 
This is still not a reason to leave your system 'wide open'.  

Also, does bb have a login to your system?  You might want to look at the aliases file to make sure that messages sent to bb do not go to another mailbox, such as root.

As far as rebuilding the sendmail.cf file, I don't know if m4 is the correct program.  My experience with sendmail is very limited.  I do know that the DAEMON_OPTIONS line above does limit sendmail inbound connections to only your local machine.

James McKenzie