[CentOS] Firewalling SMTP

Sun Jan 14 16:31:51 UTC 2007
Mike Kercher <mike at vesol.com>



	From: centos-bounces at centos.org
[mailto:centos-bounces at centos.org] On Behalf Of Don Knott
	Sent: Sunday, January 14, 2007 8:09 AM
	To: CentOS mailing list
	Subject: Re: [CentOS] Firewalling SMTP
	On 1/14/07, Denis Croombs <denis at croombs.org> wrote: 

		I have a Centos server and I want to only accept mail
for the local users
		from 3 mail servers, but I still want the users to be
able to send emails
		through this server, If I firewall the SMTP port to my 3
mail servers is 
		there any way users will be able to still send via the
main POP server ?
		(currently using Sendmails SMTP-Auth)

I would setup SMTP-Auth and have sendmail ALSO listen on port 587 for
users' to relay their mail.  An external mail server would not attempt
to deliver mail to a port other than 25.  I'd use iptables to drop all
connections to port 25 except for the 3 external hosts you
want...problem solved.