port forwarding port 25 made me an open spam relay.

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port forwarding port 25 made me an open spam relay.

This thread has been locked for further replies. You can start a new thread to share your ideas or ask questions.
port forwarding port 25 made me an open spam relay.
port forwarding port 25 made me an open spam relay.
2013-04-13 00:03:35
Region : Australia

Model : TD-8810

Hardware Version : V1

Firmware Version :

ISP :


Hi all,

I have a 8810 here that I was using as my main ADSL router/modem. I had it setup to port forward traffic to the various servers behind it.

For example port 25 went to the private IP internal mail server, port 80 to the web server and so on. I've been doing this without problem for years with Billion, Netgear, Siemans and other modem/routers...

My mail server is setup to not relay mail for anyone except the local network and this has always been fine. With the 8810 however, the mail server became an open relay as it saw all the port forwarded 25 external traffic as from a local address, (presumably the local IP of the router.) and relayed all of it. The end result was my server sending 50,000 spam emails until I figured out what had happened and pulled the plug on the 8810 and put the Billion 7300 back in its place.. a quick test showed that it was no longer an open relay.

It seems the 8810 is readdressing the packets as if they are internal traffic before sending them onto the internal machine... Does anyone know if it'ss possible to fix it or work around it in the settings?? As I said, this is the first time I've had this issue with most of a dozen other modem/routers over the years.

I suppose I can change the mail server so it treats the internal private IP of of the 8810 as untrusted.. but that is a hack I don't really what to resort to..

Can any gurus help me out?


regards

Frank
Perth Australia.
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