Thanks!! I added another rule to allow udp on port 53 and that seems to have
resolved the issue.
Thank you for your keen eye.
------------------------
Keith Smith
--- On Sat, 3/30/13, Paul Mooring <[email protected]> wrote:
From: Paul Mooring <[email protected]>
Subject: Re: IPTable interfering with email.
To: "Main PLUG discussion list" <[email protected]>
Date: Saturday, March 30, 2013, 6:05 PM
Hi,
Iptables is some of the most misunderstood software around. It isn't actually
a service that can be started and stopped, but rather the user interface for
the networking filter in the Linux kernel (net filter). I am curious as to
where this config came
from and if that's the running config while iptables is "started". Starting
the iptables "service" on nearly all distros just runs the equivalent of:
iptables –F
iptables –t nat –F
# Maybe flush some more tables if you have any
source /path/to/some/saved/rules.sh
The command 'iptables-save' will show you the currently running config to see
if it differs from your saved config. Your rules for the most part look like
they should be valid for a mail server. The only irregularity is allowing tcp
port 53. If your
server is using it's own IP as a DNS server (not 127.0.0.1 but like
192.168.0.x or something), DNS is generally UDP traffic so it's possible
iptables is killing DNS on the server and mx lookups along with it because you
have tcp/53 allowed and udp/53 blocked.
--
Paul Mooring
Systems Engineer and Customer Advocate
www.opscode.com
From: keith smith <[email protected]>
Reply-To: Main PLUG discussion list <[email protected]>
Date: Friday, March 29, 2013 2:12 PM
To: Main PLUG discussion list <[email protected]>
Subject: IPTable interfering with email.
Hi,
I am puzzled.
I cannot receive or send email when I have IP table on, except to Yahoo.com. I
get bounded emails when trying to send.
As soon as I stop IPTables I start receiving emails.
CentOS 6.4, Postfix, dovcott, Spamassassin, virtual host server running on my
business cox account (no blocked ports).
Router ports that are open 21,22,25,53,80,143,443,587. (port forwarding)
IPTable config:
# Generated by iptables-save v1.4.7 on Fri Mar 29 14:08:56 2013
*filter
:INPUT DROP [0:0]
:FORWARD DROP [0:0]
:OUTPUT ACCEPT [4:432]
-A INPUT -s 192.168.20.0/24 -p tcp -m tcp --dport 22 -j ACCEPT
-A INPUT -s x.x.x.x/32 -p tcp -m tcp --dport 22 -j ACCEPT
-A INPUT -s x.x.x.x/32 -p tcp -m tcp --dport 22 -j ACCEPT
-A INPUT -p tcp -m tcp --dport 25 -j ACCEPT
-A INPUT -p tcp -m tcp --dport 53 -j ACCEPT
-A INPUT -p tcp -m tcp --dport 80 -j ACCEPT
-A INPUT -p tcp -m tcp --dport 143 -j ACCEPT
-A INPUT -p tcp -m tcp --dport 443 -j ACCEPT
-A INPUT -p tcp -m tcp --dport 587 -j ACCEPT
-A INPUT -i lo -j ACCEPT
-A INPUT -m state --state RELATED,ESTABLISHED -j ACCEPT
COMMIT
# Completed on Fri Mar 29 14:08:56 2013
Thank you for any insight.
Keith
------------------------
Keith Smith
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