I have a static IP address from my ISP. I also have a router with a built in Modem so I plug the router into the telephone line. If I make a direct connection from my router to my PC with the following addresses on my PC everything works fine, I get a connection to the internet (can view webpages):

IP: Subnet: Default Gateway:

Preferred DNS : Alternate DNS :

As soon as I connect my Cisco 501 PIX in between the PC and the router, I don't get any internet connection. Here are the steps I am following to configure the firewall, so please guide me where I am going wrong:

I start the PDM by going to Once started and authenticated get the Basic Configuration and I leave the default values ( PIX Host Name = pixfirewall, Domain Name:

On the next page "Outside Interface Configuration" I leave the "Speed to Auto" and I select "static IP address" and input the following details IP, Subnet Mask: and Default Gateway:

On the next page I leave the remote VPN page empty

On the next page I also leave the Auto update Configuration empty

On the next page "Other Interfaces Configuration I can see the Inside and outside interface settings and the inside has a security level of

100 and the outside has 0.

On the next page "NAT and PAT Configuration" I select "do not translate any addresses.

On the next page I disable the DHCP because I can allocate a specific IP for the PC connecting to the Firewall.

After applying all these setting and saving them. I specify TCP/IP for my PC with the following addresses:

IP: Subnet Mask: Default Gateway :

I try to connect to the internet but I will not let me connect. For some reason Skype is able to connect which is quite strange.

Do I need to configure anything more? Why does it not allow me to connect to the internet?

When I remove the firewall I am getting a connection. Please can you guide me?

Thank you, James

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If you use one of the IP address ranges reserved for private use, NAT is required for connectivity with the internet.

This concerns addresses like: to, to, and to


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for details regarding the use of these addresses.


If I understand you correctly, you only need to enable NAT+PAT. PAT is not really needed unless you have more than one machine, but it is commonly used anyway. In fact, most other vendors don't separate the two, but simply calls the entire process "NAT".

By this you mean "remove the firewall and configures the PC to use"?

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