[ILUG] etrn & ipchains

[Stephen Shirley]

On Tue, 5 Sep 2000 gerdono at eircom.net wrote:

> I have configured a firewall using ipchains kernel 2.2.16
> everything works except for my mail delivery. Mail Server is on another server and use ETRN deliver to eircom.
> ETRN command is traversing the firewall no problem but returning mail only comes as far as the firewall machine and does not get back to Mail Server.
> Mail Server is VPOP3 (NT Server) 
> I think my problem is due to the messages been delivered on a different port ??
> Anyone got any ideas or config something similar
> 
> regards ger donohue
> 

Hi,
I persume that you're using ip_masq. The problem is that
when eircom try to deliver the mail, they're making
an unsolicated connection as far as the firewall is concerned.
This means that eircom's connection is not being forwarded to your
machine. Instead it is trying to connect to port 25 on the
firewall. What you need to do is one of two things:

1. Setup sendmail on the firewall so that it will forward
all incoming mail to your machine.

2. Install port forwarding and set it up to forward all
connections to port 25 on the firewall to port 25 on your machine.

If you need any help, just send me a mail.

Steve