Fedora core 1 sendmail problems

Mon Mar 29 03:03:17 UTC 2004

In reviewing this thread it seems to me there could be an underlying network issue not related to the sendmail configuration, despite port forwarding for port 25 apparently working as before. Although the MTA is accepting connections from hosts on the local IP network (you can telnet to port 25 as Alexander reminded me) it may not be able to send a response to a host over the Internet.

As others have suggested, it's best to rule out network configuration problems, e.g., a wrong netmask or router setting that would not affect local traffic but that would break IP connections from remote networks. What you're observing might be produced, for example, if the route to the remote network were incorrect, i.e., your server gets the TCP connect via port redirection through your NetGear box and sends an ACK but the remote never gets it because the ACK never leaves the local network (routing problem, e.g., bad netmask).

What happens when you try to telnet from a remote host (not on your local network)? If the connection is dropped right away it would suggest that the originating host cannot get a connection on port 25. If the connection times out, e.g., after a few seconds, it would suggest a firewall or routing issue, i.e., packets are lost or discarded/dropped. I suspect you'll find the latter.

Ron

Homer Sapions wrote:
> 
> My sendmail.cf has
> O DaemonPortOptions=Name=MTA
> 
> and /etc/mail/relay-domains has
> localhost
> myserver.mydomain.org
> myserver2.mydomain.org
> myserver3.mydomain.org
> 
> because I have Apache set up with multiple virtual hosts, and want to be
> able to receive mail at any of the registered server names. sendmail.mc also
> has
> MASQUERADE_AS(`myserver.mydomain.org')dnl
> to ensure that all mail appears to come from one location.
> 
> >From: Ron Herardian <rherardi at gssnet.com>
> >Reply-To: For users of Fedora Core releases <fedora-list at redhat.com>
> >To: For users of Fedora Core releases <fedora-list at redhat.com>
> >Subject: Re: Fedora core 1 sendmail problems
> >Date: Sun, 28 Mar 2004 16:31:47 -0800
> >
> >Homer,
> >
> >Double check that "Addr=127.0.0.1" is removed from the sendmail.cf file.
> >The sendmail.cf file is only rebuilt on restart (or if you run make in
> >/etc/mail) of sendmail if and only if you have the sendmail-cf package
> >installed. This is the most common problem on Red Hat.
> >
> >FYI, here's one way to do a basic sendmail setup (there are others),
> >assuming that the sendmail-cf package is installed:
> >
> >1. Go back and uncomment "# DAEMON_OPTIONS(`Port=smtp,Addr=127.0.0.1,
> >Name=MTA')dnl"
> >2. Modify the line to read "# DAEMON_OPTIONS(`Port=smtp, Name=MTA')dnl"
> >    Note: We are deleting "Addr=127.0.0.1"
> >3. If this is a relay edit /etc/mail/relay-domains and add your domain
> >(unless this is the server where all mailboxes reside)
> >    Note: /etc/mail/access does not need to contain anything if you're
> >using /etc/mail/relay-domains because relay-domains says that no mail is
> >relayed except mail destined for the domains listed (regardless of who's
> >sending it), i.e., you accept mail for your domain and not mail to be
> >relayed to other domains
> >4. Restart sendmail.
> >
> >That's about all you need to do to get sendmail working for your domain and
> >not as an open relay. Of course this assumes your IP address, router,
> >netmask, host name, and domain name servers are all set up correctly.
> >
> >Ron
> >
> >
> >
> >
> >Homer Sapions wrote:
> > >
> > > I have been searching the archives of this list and google and not yet
> >found
> > > the solution to my problem. It seems like this is a common problem with
> > > sendmail on new installations of Fedora, so I am frustrated by not
> >finding a
> > > solution that works for me. I would really appreciate any help.
> > >
> > > I had a RedHat 7.3 installation working properly, both sending and
> >receiving
> > > mail with sendmail. I wanted a clean Fedora install, and since then I
> >can
> > > send, but not receive mail.
> > >
> > > I have modified /etc/mail/sendmail.mc and commented out the line
> > > dnl # DAEMON_OPTIONS(`Port=smtp,Addr=127.0.0.1, Name=MTA')dnl
> > > then ran make -C /etc/mail and restarted sendmail with service sendmail
> > > restart.
> > >
> > > I also modified /etc/mail/access and added
> > > localhost.localdomain           RELAY
> > > localhost                       RELAY
> > > 127.0.0.1                       RELAY
> > > myserver.mydomain.org   RELAY
> > > then restarted sendmail.
> > >
> > > I have a 4 port linksys as a router/firewall between my cable modem and
> >my
> > > server (and 2 other PCs). Port forwarding is enabled on the linksys to
> >allow
> > > http traffic, and smtp on port 25 to be forwarded to the server - which
> >was
> > > all working correctly before the Fedora install.
> > >
> > > I ran ethereal and watched connections, not that I understand much of
> >the
> > > packet info. I see connection attempts, but external mail servers never
> > > complete a connection. The typical pattern seems to be a remote server
> >sends
> > > a SYN on port 25, I reply with SYN,ACK. Remote sends a SYN, I send 2
> > > SYN,ACKs. Remote sends a SYN, and I send 3 SYN,ACKs, and eventualy the
> >rmote
> > > gives up.
> > >
> > > >From any PC inside my network I can telnet to the server on port 25 and
> > > issue basic smtp instructions. I can do the same locally with 127.0.0.1
> > > e.g.
> > > # telnet myserver.mydomain.org 25
> > > Trying 192.168.1.12...
> > > Connected to myserver.mydomain.org.
> > > Escape character is '^]'.
> > > 220 myserver.mydomain.org ESMTP Sendmail 8.12.10/8.12.10; Sun, 28 Mar
> >2004
> > > 11:41:01 -0500
> > > mail from: someone at xxx.org
> > > 250 2.1.0 someone at xxx.org... Sender ok
> > > rcpt to: homer
> > > 250 2.1.5 homer... Recipient ok
> > > data
> > > 354 Enter mail, end with "." on a line by itself
> > > Subject: test message
> > > this is a test
> > > --
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> >
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> >
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