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TOPIC: Redirecting mail with IPCOP

Redirecting mail with IPCOP 12 years 7 months ago #12637

I'm trying to redirect all mail packets (POP3 and SMTP) in the local network to a specific host. I'm trying with the following rules:

## Changes destination address of the smtp packets,
## port 25
iptables -v -t nat -A PREROUTING -p tcp --dport 25 -i eth0 -j DNAT --to

## Changes destination address of the pop3 packets,
## port 110
iptables -v -t nat -A PREROUTING -p tcp --dport 110 -i eth0 -j DNAT --to

Where eht0 is the green interface of the IPCOP firewall and is a knoppix host wich sends back to the source address any mail it receives.

I send a mail to the knoppix system with and want the firewall to redirects it to the knoppix host and then redirect the reply to another host at

I don't know if I explain myself clearly. The point is that the rules above don't do anything. Thanks for your help.

[edit] Sorry about the duplicated post. I'm still sleepeth :oops: :oops:

Re: Redirecting mail with IPCOP 12 years 7 months ago #12642

  • DaLight
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If the source and destination addresses are both in the same subnet (GREEN), routing changes on your IPCOP will not have any effect.

Re: Redirecting mail with IPCOP 12 years 7 months ago #12652


So, if I understand you, I can't redirect mail packets (smtp and pop3) in the same subnet with iptables rules??

Could you tell me another method to do this?? This firewall is going to be in a honeynet and the purpose of it is to capture the ougoing mail packets, wich a test malware at the honeypots will try to send, and redirect it to an analysis machine.

Thank you for your help!!


I'm thinking about placing the knoppix system in a DMZ with an Orange card.

Any smtp or pop3 related packet generated in the green card (the honeynet) subnet will be redirected to the knoppix system in the orange card, wich will reply the messages to the sender. The honeywall will redirect the reply to an analysis system in the green card.

Is that possible??
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