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Open ports with multi-NAT on ADSL2MUE

Discussion in 'Other Linksys Equipment' started by ms526, Sep 22, 2006.

  1. ms526

    ms526 LI Guru Member

    Hi,
    I've recently recevied a brand new Linksys ADSL2MUE ADSL modem to replace my Zyxel Prestige 660H. I'm quite impressed with it so far, as it's actually noticably faster than the Zyxel.

    I have a /29 subnet of public IP addresses on my 8m/448k ADSL connection from my ISP (Entanet), which means 6 useable addresses if you inlcude the one for the router itself. With the Zyxel, I'm using 1 IP address for my web/mail server by using one-to-one NAT, and another IP address which is shared between my standard desktop and laptop PCs. I'm saving the others for more servers which I plan on adding in the near future.

    Now, I'm aware that the featureset of the ADSL2MUE is very limited and does not support one-to-one NAT or port forwarding, but as it's basically a Linux router I logged into it using an SSH client and got into the shell environment. I then used the iptables command to configure one-to-one NAT mappings, using the following commands:

    iptables -t nat -A POSTROUTING -s 192.168.1.2 -j SNAT --to 1.2.3.4
    iptables -t nat -A PREROUTING -d 1.2.3.4 -j DNAT --to 192.168.1.2

    *1.2.3.4 represents my external IP

    and this seemed to work fine, as my PC was then using the external IP address I had assigned to it in the modem.

    I also assigned an address to my webserver. However, even though this worked ok, all the ports still seem to be blocked, and I need to open port 80 and 25 to my webserver. I'm sure that this is just another iptables command, but i'm not sure how I would go about it as I'm not an expert at linux/unix, but do know basic commands.

    Could someone please tell me how to do this?

    Thanks.
     

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