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New Member

PIX 501 with private IP


We are using a PIX 501 behind a DSL modem. We have a single public IP address assigned to the outside interface of the modem, a single private IP address on the inside interface of the modem and a single private IP on the outside interface of the PIX. How can we route traffic (smtp / remote desktop (tcp 3389))pointed to the public IP (outside interface of the modem) to a system on the private subnet on the inside interface of the PIX?

Example: DSL modem outside:

DSL modem inside:

PIX outside: (gateway

PIX inside:

We want to route smtp / terminal services directed to to server Thanks.

Cisco Employee

Re: PIX 501 with private IP

What DSL modem is it. Is it a DSL router? I think it should have the NAT/PAT capability. you need to first configure it to redirect the particular traffic towards pix.

then configure pix for static translations and access-lists

New Member

Re: PIX 501 with private IP

Thanks - it is a DSL modem, ActionTec 1524. All I can do on it is turn NAT off. I have set port forwarding on it to pass both port 25 and 3389 to the outside address of the PIX ( and set the access-list in the PIX to allow those ports to pass to the server (, do I need to set up a static route from (outside PIX) to (Server)?

New Member

Re: PIX 501 with private IP

Assuming you want to remote-desktop TO the inside pc ( FROM an internet address, you would need to NAT the inside pc to a static global IP address.(seperate from DSL modem's external IP or PAT to specific port using the DSL modem extrenal IP)

When you access internet from your internal pc's ( the source address is your DSL modem external IP, becuase of NAT. The return traffic is hence translated to the original private ip and forwarded to internal pc's.

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