this is strange...
Ive got another mailserver 172.24.128.56 .. now if I put that rule in
iptables -t nat -A OUTPUT -p tcp -m multiport --dports smtp -j DNAT --to-destination 192.168.12.56
and if I try telnet to any mail server on the internet , i connect to 192.168.12.56 (Which should happen on 172.20.128.56)
[root@poscpt0h01 root]# telnet 196.31.155.18 25
Trying 196.31.155.18...
Connected to 196.31.155.18.
Escape character is '^]'.
220 prxsaa0z02.ipnetwork.co.za ESMTP Sendmail 8.12.8/8.12.8; Fri, 8 Apr 2005 17:30:45 +0200
is there noway to make it connect directly to 196.31.155.18, but using 192.168.12.56 as a gateway
----- Original Message ----- From: "Rob Sterenborg" <rob@xxxxxxxxxxxxxxx>
To: <netfilter@xxxxxxxxxxxxxxxxxxx>
Sent: Friday, April 08, 2005 12:58 PM
Subject: RE: Redirecting mail
Now what i would like to know is there a way I could route all out going mail from 172.20.128.56 to 192.168.16.56 using iptables DNAT.
First of all, is it possible to do what I want to do? and
The networks seem to be connected, so can't you just configure a smtp-forwarder in your MTA configuration ? That would be easier I think.
would I use iptables or iptables with something else?
No, just iptables would be enough.
This is what ive tried...
on 172.20.128.56 (Red Hat Linux release 7.3) i issue the command : iptables -t nat -A OUTPUT -p tcp -m multiport --dports smtp -j DNAT --to-destination 192.168.12.56
There is no need to use multiport because you only DNAT 1 port : smtp. But that should not be a problem.
iptables -t nat -A OUTPUT -p tcp --dports smtp \ -j DNAT --to-destination 192.168.12.56
now when im on 192.168.12.56 (Red Hat Linux release 9 (Shrike) ) and do a tcpdump greping for smtp I see connections from 172.20.128.56 but not exactly sure what its doing.. but what i know, from 172.20.128.56 I cant make smtp connections out to the internet..
A few obvious tests : Do you see mail coming in from 172.20.128.56 into the queue of 192.168.12.56 ? Is mail from 172.20.128.56 "for the internet" being delivered ?
If it's not working, do you have other iptables rules that prohibit this from working ?
Gr, Rob
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