DSL Modem and PIX. Gateway?

Posted on 2005-05-12
Last Modified: 2013-12-14

  Hi everyone

  I've just got a Cisco PIX 501 with Cisco 6.2(1) software on it.

  Can PIX replace my existing "noname" router?

 I have a DSL Modem connected to a router. The routers external IP is static, and cannot be obtained by either PPPoE or DHCP. According to my ISP i have to define an external IP, a mask, and a gateway. If i dont define an external gateway, the router cant connect me to the internet.
   I cant find anything in the PIX firewall about an external gateway. If connect the DSL modem to the PIX external interface and define the static IP on the PIX it cant connect me to the internet. If i leave my old router on the DSL modem, and connect the external interface on the PIX to the LAN, and my own computer to the internal interface on the PIX, the PIX external IP will be obtained by DHCP (IP, subnet, AND gateway) and is now able to connect.

Where do i define this gateway, like on my router?

Question by:Shaohs
    LVL 40

    Accepted Solution

    You certainly can replace your 'router' with the PIX 501...

    The external gateway is basically a 'default route' whereas any traffic that does not belong within your lan is pushed out to that address...  So, I think (and I am not a PIX guru) that you need to add that route to your external interface...

    Use the route command to set a default route to the outside router. Use the show route command to view the command you entered. If needed, use the no route command to remove a route command. If the outside router is at address, you would use this command:

    EX:  route outside 0 0 1

    This command states that the default router is on the outside interface. The 0 0 information is an IP address of and mask of, which the PIX Firewall associates with the default route. The route command could be read as "if I have a packet intended for IP address, send it to instead." The "1" at the end is the number of hops that the router is from the PIX Firewall. Hops are routers, so 1 hop is the router nearest the PIX Firewall.

    Author Comment


      That helped alot. Thanks for the tip :-)
    LVL 40

    Expert Comment

    Great!  Good luck, and thank you!


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