{Disarmed} Re: telnet on local LAN question

[Craig White]

On Thu, 2011-08-18 at 20:47 -0700, Paul Allen Newell wrote:
> [root at yoyo ~]# netstat -anp | grep ":25"
> tcp        0      0 127.0.0.1:25                0.0.0.0:*
> LISTEN      1510/sendmail: acce 
> [root at yoyo ~]# netstat -anp | grep ":23"
> [root at yoyo ~]#
> +++
> 
> I'm staring at man netstat and the description of local address,
> foreign address, and state ... but not certain what it really means in
> context of your question regarding listening ... I think I am supposed
> to assume that this output means 127.0.0.1:25 is listening to anything
> sent from 0.0.0.0:* ? 
----
I believe that means that you can only connect to port 25 from localhost
and not any other computer.

It's been many years since I used sendmail (I heavily recommend postfix)
but I think if you edit /etc/mail/sendmail.mc and find the section...

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

and chnage the last line to
dnl DAEMON_OPTIONS(`Port=smtp,Addr=127.0.0.1, Name=MTA')dnl

and restart sendmail to enable it to listen on all your network
interfaces.

Note that you then have to edit /etc/mail/access to control who can
'relay' email (and restart sendmail again).

also note that generally running your own smtp server requires you to
have a dns server so you have an mx record so it becomes obvious which
server receives e-mail for your domain.

Craig


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