RE: Fedora core 1 sendmail problems
I did some testing in a roundabout fashion, and proved that sendmail is
configured and working the way it should. Because it is much easier to debug
a problem like this when you see it yourself, I opened a VPN tunnel to one
of my servers at work. Our firewall is configured to not allow any outbound
connections on port 25, because all company mail must be sent via our
internal mail servers/relays. I shut down my web server locally because I
know that traffic on port 80 is coming in and out.
I added to my sendmail.mc
DAEMON_OPTIONS(`Port=80,Addr=0.0.0.0, Name=MTA')dnl
ran make -C /etc/mail
then stopped and restarted sendmail. I verified that locally I could connect
on port 80 and get the usual sendmail connection. I then went to another
terminal session connected via VPN to one of my servers at work, connected
to my own server on port 80 and got what I expected - a sendmail prompt. I
did the normal trickery of mail from: xxx(a)yyy.com, rcpt to: homer, data etc.
then disconnected.
I checked my local account, and the message is there as I expected. So the
problem is obviously not with sendmail, it has to be the linksys, the cable
modem or the ISP. The linksys config is really easy and almost impossible to
set up port forwarding incorrectly. I'm not aware of any way to configure
the cable modem. The only problem I am aware of is that the firmware on my
linksys is rather old (1.42.3, Jan 28 2002) and the latest firmware doesn't
want to install on it. This may be a problem. At least now I have a definite
direction (or 3 directions!) to go in.
Thanks everyone for the help and suggestions, I will let you know the
solution when I find it.
From: "Robert Boucneau" <rboucneau(a)tuckernt.net>
Reply-To: For users of Fedora Core releases <fedora-list(a)redhat.com>
To: "For users of Fedora Core releases" <fedora-list(a)redhat.com>
Subject: RE: Fedora core 1 sendmail problems
Date: Tue, 30 Mar 2004 17:49:01 -0700
Hi Homer,
I'm jumping in late here, but I have read all the preceding messages...it
looks to me as though Alexander, et. al. have all the sendmail issues
covered. If sendmail works inside and you have your gateway properly
configured (which it appears you think you do) then this should not be a
sendmail issue.
To completely rule out sendmail, I'd suggest setting up a telent server to
listen on port 25 (after turning off sendmail) and seeing if you can log in
for the outside. If you *can* it's sendmail's configuration. If not, it's
either your OS *or* your network. (Personally, I'd skip this step and go
right to the networking suggestions below...but this is a valid first
step...)
Put another machine on your email server's IP address and try to connect to
it. That will either show the problem to be internal or external to your
machine. (I'm guessing external.)
If it's internal to your machine (i.e. you can log onto a different
machine's port 25 from the outside if it is on your server's IP address),
you can troubleshoot the networking components of your system (the
Netfilter
(iptables) guys have some pretty clean ways to watch packets transit your
system, if you want to troubleshoot) or reinstall the OS (I'd scrub and
install, myself, but that's just an opinion.)
If it is external to your machine (my guess), then it is either your
firewall/router, your cable-modem, or the ISP's router. I'd guess it's
your firewall/router or your cable modem (the cable modem is actually a
sort
of router, not a modem, and it has Network Address Translation, too. so it
could be dropping reply packets silently...)
To test this, I'd put a machine on the "outside" of your Linksys
router/firewall and see if it can connect (i.e. eliminate the cable modem)
or I'd remove the firewall/router and see if things work with just the
cable-modem.
My guess is that in one of those configurations you'll be able to connect
from the outside. Whichever device is not connected is the culprit. I'd
guess it is the cable modem and you'll have to reconfigure NAT on it...
I hope this helps.
All the best,
Bob
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