Re: TCP redirect external to external host

[Michael Gale <mgale@utilitran.com>]

hmmm.... what about ICMP redirect ?

I can not remember if the host you are redirecting to has to be on the same subnet as the client host :(

If so then it would not work.

Michael.

On Tue, 9 Dec 2003 20:40:19 +0100
Örjan Persson <orange@fobie.net> wrote:

> Antony Stone (Antony@Soft-Solutions.co.uk) wrote:
> > 
> > If it is not true that the real source IP and the real destination IP exist on 
> > the same interface of the netfilter machine, repost your query with a bit 
> > more detail and we may be able to help futher.
> > 
> 
> The situation is that I have a hostname where there are both SMTP and
> DNS services atm. The mail service is beeing migrated to another host,
> and since I can't just change the IP for the hostname (would break DNS
> services) I would like to have a temporary redirect to the new
> mailservice for the SMTP-service, until the ppl using it has changed
> their mail settings to use the new hostname.
> 
> So, I have two external host with two external IP's. They exists on the
> same subnet too. Both uses the same gateway.
> 
> These are the rules I tried to use, which translates the users IP to the
> first servers IP:
> iptables -t nat -A PREROUTING -p tcp --dport 33 -i eth0 -j DNAT --to host2:44
> iptables -t nat -A POSTROUTING -d host2 -p tcp --dport 25 -j SNAT --to host1
> 
> Hope that's enough information to get you into my problem!
> 
> Thanks for letting me take your time! :)
> 


-- 
Michael Gale
Network Administrator
Utilitran Corporation