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Re: NAT detection
- To: misc_(_at_)_openbsd_(_dot_)_org
- Subject: Re: NAT detection
- From: Anthony Schlemmer <aschlemm_(_at_)_attbi_(_dot_)_com>
- Date: Wed, 4 Dec 2002 13:07:59 -0800
- Organization: AT&T Broadband
I setup sendmail on my gateway system and us it to relay email to my
ISP's mail servers. I can't send email directly from my box since I
have a DHCP assigned IP address and most mail servers reject any email
coming directly from my system. My ISP's mail servers on the other hand
readily accepts my system's email since my system is on their network.
I generally use a POP3 client on my workstation but I have some programs
that need to send email and want to us the "mail" command so I setup
sendmail. I also have other systems on my network that run sendmail and
route everything to my gateway system which then relays the email on to
The biggest problem I faced with this setup was getting a proper "From:"
header in my email messages since my internal network uses RFC1918
addresses and has a bogus domain name so I needed to have my email
headers rewritten to use my email address at my ISP.
My ISP doesn't allow servers either so I have access to all of my
services blocked via "pf" but that still allows sendmail to send
outgoing messages while blocking all incoming connections.
On Wednesday 04 December 2002 12:15 pm, Steven Sluter wrote:
> On Tue, 4 Dec 2002, Jean-Yves Burlett wrote:
> > Okay ... why do they want customers in the first place ? :)
> > Anyway, one solution would be to proxy just about everything,
> > masquerading User-Agents and all, using a local smtp server that
> > forward everything to the ISP's SMTP server and sanitize message
> > headers.
> So anyone know how to change the headers for qmail? I had to set up
> a local smtp server because i've got dynamic ip and my mail kept
> getting rejected by spam filters. My ISP doent allow servers, so I
> want to disguise my smtp server before they find out....