Re: Two gateways on same network

[Craig Sanders <cas@taz.net.au>]

not an answer to your problem, just some info for you to consider:

On Thu, Dec 07, 2006 at 04:57:03PM +0200, Hans du Plooy wrote:
> 4mbit ADSL = 192.168.1.6
> 128k line = 192.168.1.1
> 
> [...]
> 
> So basically the leased line would be a backup MX.

presumably the slow 128k line is the leased-line?

be aware that a backup MX will get bombarded by incoming spam, as
spamware is often written to prefer backup MX to primary MX (as an
attempt to get around anti-spam rules on the primary).

an easy solution is to have an even lower priority MX record pointing to
either an unused IP address or an IP which does not have an smtp daemon
listening. then the spamware will use this in preference to your real MX
servers.

(note: don't use private rfc1618 addresses for this fake MX. they
may not exist on your network but may exist on a legitimate sender's
network, causing legit mail to disappear when your links are down)

e.g. for my own domain:

$ host -t mx taz.net.au
taz.net.au          	MX	10 taz.net.au
taz.net.au          	MX	50 mx2.taz.net.au

$ host mx2.taz.net.au
mx2.taz.net.au      	A	203.16.167.31

there isn't even a machine on my network with that IP (and never will
be - i can afford to blow an IP address to reduce/delay incoming
spam), and i also have an iptables DROP rule for incoming packets to
203.16.167.31:25 so that the spamware takes ages to time out rather than
getting a quick 'no route to host' response.



craig

-- 
craig sanders <cas@taz.net.au>           (part time cyborg)