[TriLUG] e-mail configuration question

[That One Guy]

If you're running sendmail on a recent version of RedHat, sendmail by default 
only listens on the loopback interface (127.0.0.1).  That's one possibility.  

Have you checked /var/log/maillog to see if there's even a connection being 
made to your machine?  Also, do a "netstat -an | grep :25" and see what IP 
Addresses your MTA is bound to.

It should look like this:
tcp        0      0 0.0.0.0:25              0.0.0.0:*               LISTEN

If that "0.0.0.0" is "127.0.0.1" instead then sendmail is not listening on 
your ethernet interface.

Once you get your MTA listening on the ethernet interface, you may need to 
tell it who (i.e.- what domain and hostnames) it is to accept mail for.  
That's another discussion.

Check out the: 
RedHat Sendmail FAQ:
http://www.moongroup.com/docs/rh-sendmail/index.html

RedHat Sendmail How-To
http://www.moongroup.com/docs/RH-sendmail-HOWTO/

Hope this helps,
TOG

On Thursday 07 February 2002 01:19 pm, gregbrown at mindspring.com wrote:
> All:
>
> I am attempting to use my Linux lab machine as my primary source for e-mail
> while at work.  E-mail works great as long as it is sent between users on
> the same machine (i.e. mail -s "test" username) but when I attempt to
> e-mail my account from outside of my machine (i.e. sent to
> username at vtcdev.gc.lucent.com) the mail never arrives.  This happens when I
> send e-mail from outside of Lucent or from the Lucent network (just from a
> different machine on the network).
>
> I am using Kmail as my client (along with xbiff).  I have Kmail configured
> to look for e-mail in /var/spool/mail/user and it sees e-mail here as long
> as it was generated from the same machine.
>
> So now I'm left with two possibilities in this scenario:
>
> 1. there is a firewall somewhere on the LAN which is intercepting my
> e-mails destined for vtcdev and is dropping them
>
> 2. something isn't configured correctly on vtcdev to allow for e-mail to be
> recieved from machines other than itself
>
> Any suggestions?  I see port 25 defined in /etc/services and it appear my
> IP Chains should be allowing incoming mail (ipchains file at the end of
> this e-mail).
>
> Greg
>
>
>  Firewall configuration written by lokkit
> # Manual customization of this file is not recommended.
> # Note: ifup-post will punch the current nameservers through the
> #       firewall; such entries will *not* be listed here.
>
> :input ACCEPT
> :forward ACCEPT
> :output ACCEPT
>
> -A input -s 0/0 -d 0/0 25 -p tcp -y -j ACCEPT
> -A input -s 0/0 -d 0/0 80 -p tcp -y -j ACCEPT
> -A input -s 0/0 -d 0/0 21 -p tcp -y -j ACCEPT
> -A input -s 0/0 -d 0/0 22 -p tcp -y -j ACCEPT
> -A input -s 0/0 -d 0/0 23 -p tcp -y -j ACCEPT
> -A input -s 0/0 67:68 -d 0/0 67:68 -p udp -i eth0 -j ACCEPT
> -A input -s 0/0 67:68 -d 0/0 67:68 -p udp -i eth1 -j ACCEPT
> -A input -s 0/0 -d 0/0 -i lo -j ACCEPT
> -A input -s 0/0 -d 0/0 -i eth0 -j ACCEPT
> -A input -p tcp -s 0/0 -d 0/0 0:1023 -y -j REJECT
> -A input -p tcp -s 0/0 -d 0/0 2049 -y -j REJECT
> -A input -p udp -s 0/0 -d 0/0 0:1023 -j REJECT
> -A input -p udp -s 0/0 -d 0/0 2049 -j REJECT
> -A input -p tcp -s 0/0 -d 0/0 6000:6009 -y -j REJECT
> -A input -p tcp -s 0/0 -d 0/0 7100 -y -j REJECT
>
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-- 
That One Guy (TM)			trilug at ichi.net