From: Wietse Venema (no email)
Date: Sat Oct 27 2001 - 18:19:01 EDT
That is bad advice.
If your line goes down for a non-trivial amount of time then someone
else is going to get your IP address and your mail.
If you set your DNS time-to-live too short then your domain disappears
while your link is down for a non-trivial amount of time.
In both cases you are likely to lose mail.
SMTP is designed to survive significant network outages.
Please do not break the reliability of SMTP with optimistic design.
> Most ADSL or cable modem connections have dynamic IP addresses with
> very long lifetimes. I have had the same IP address for six months.
> In the last two years, the only time my dynamic IP address has changed
> is multi-hour power outages, vacations when I was unwilling to trust
> my firewall for several weeks unattended, and trashing the lease
> file. As long as the IP address is much longer than a reasonable DNS
> time to live, and the secondary boxes are listed in some MX record,
> port forwarding is unnecessary.
> Quoting Wietse Venema <>:
> > If your inside machines have a dynamic public IP address, you will
> > always need at least one machine with a static IP address on the
> > public Internet.
> > In order for the ADSL boxes to look like they have a static public
> > IP address, use sshd port forwarding out of the box, or SOCKSify
> > Postfix on the inside machines. You'd have to set up virtual
> > interfaces on the well-connected machine, one virtual interface
> > for each inside machine.
> I don't do Windows and I don't come to work before nine.
> -- Johnny Paycheck
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