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Port Forwarding

Discussion in 'Tomato Firmware' started by mikester, Oct 14, 2007.

  1. mikester

    mikester Network Guru Member

    I'm trying to forward port 75 to port 25 (PAT or Port Address Translation) for all internal to external traffic and am not having any luck getting it to work...any suggestions?

    Here's what I'm using:
    iptables -t nat -A PREROUTING -i eth1 -p tcp --dport 75 -j REDIRECT --to-port 25

    and the response I get:
    iptables: No chain/target/match by that name
  2. u3gyxap

    u3gyxap Network Guru Member

    I don't get it. You need to forward from 75 to port 25 on all comming from LAN traffic going to the internet? Or something is coming to your router on port 75 and should be translated on port 25 to your local network?
  3. mikester

    mikester Network Guru Member

    I want to forward all LAN port 75 traffic to port 25.
  4. ifican

    ifican Network Guru Member

    That would get very convoluted even if you could get it to work as you would also have to forward return traffic to port 75.
  5. mikester

    mikester Network Guru Member

    I'm not 100% sure but I don't think so.

    What I want to do is set up LAN port 75 for sending email. Correct me if I'm wrong in thinking it's one way.
  6. GeeTek

    GeeTek Guest

    You can have multiple smtp engines sending on port 25. There should be no logical reason to run over port 75 from the computer to the router, just to have it traslated back to 25 before going out to the internet. Why don't you want to leave the SMTP engine on 25 ?
  7. mikester

    mikester Network Guru Member

    Why port 75 isn't as important at this time - making Port Address Translation work is what I'm after!

    I want to be able to re-route port traffic. I can re-route traffic by source/destination IP successfully but I haven't been able to do this with ports yet.
  8. u3gyxap

    u3gyxap Network Guru Member

    PAT is when you have something knocking at your router's WAN at port 75, and you forward it to a local server in your LAN, on port 25. Is that what you are trying to achieve?
  9. mikester

    mikester Network Guru Member

    other way around - forward LAN port to WAN port
  10. ifican

    ifican Network Guru Member

    Ok lets go back to what it is you are after. You say you want to configure port 75 for sending mail. You can do this and it is possible but the server that you are sending too needs to accepts smtp on port 75 or none of this will work. Do you or someone you know have control of the server in question? And why not just set up your mail client to use port 75 instead of 25 then you dont have to do anything crazy with ports.
  11. svengru

    svengru Guest

    I am running into the same problem: I also need to forward my internal SMTP traffic from port 25 (lan) to port 587 (WAN) since my ISP is blocking port 25 traffic and I have some devices that do not have the ability to change the SMTP port (Cisco IP Cam).

    Is there alread a solution?

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